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l l=4 1lill'%WYldii.Ul~~~~~~~~~~~~~~~~~~ itA=iII1 l~w 6t*t Estimating Woody Biomass in Sub-Saharan Africa Estimating Woody Biomass in Sub-Saharan Africa

Andrew C. Miflington Richard W. Critdhley Terry D. Douglas Paul Ryan

With contributions by

Roger Bevan John Kirkby Phil O'Keefe Ian Ryle

The World Bank Washington, D.C. @1994 The International Bank for Reconstruction and Development/The World Bank 1818 H Street, N.W., Washington, D.C. 20433, US.A.

All rights reserved Manufactured in the United States of America First printing March 1994

The findings, interpretations, and conclusiornsexpressed in this publication are those of the authors and do not necessarily represent the views and policies of the World Bank or its Board of Executive Directors or the countries they represent Some sources cited in this paper may be informal documents that are not readily available. The manLerialin this publication is copyrighted. Requests for permission to reproduce portions of it should be sent to the Office of the Publisher at the address shown in the copyright notice above. The World Bank encourages dissemination of its work and will normally give permission promptly and, when the reproduction is for noncommnercial purposes, without asking a fee. Permission to copy portions for classroom use is granted through the CopyrightClearance Center, Inc-, Suite 910,222 Rosewood Drive, Danvers, Massachusetts 01923, US.A. The complete bacdist of publications from the World Bank is shown in the annual Index of Publications,which contains an alphabetical title list and indexes of subjects. authors, and countries and regions. The latest edition is available free of charge from Distribution Unit, Office of the Publisher, The World Bank. 1818 H Street, N.W., Washington, D.C 20433, USA., or from Publications, The World Bank, 66 avenue d'Idna, 75116Paris, France. The boundaries, colors, denonminations,and other information shown on any map in this volume do not imply on the part of the World Bank Group any judgment on the legal status of any ternitory or the endorsement or acceptance of such boundaries.

The cover shows a representation of the vegetation index for Africa,June 1986, derived from the NoAAsatellite's AvHRsensor.

Library of Congress Cataloging-in-Publication Data

Estimating woody biomass in Sub-Saharan Africa J Andrew C MilJington -.. [etaL]. p. cm. Includes bibliographical references and index. ISBN 0-8213-2306-7 1. Fuelwood crops-Africa, Sub-Saharan-Geographical distribution. 2 Woody plants-Africa, Sub-Saharan-Geographical distribution. 3. Forest biomass-Afirica, Sub-Saharan-MeasurenenL 4. Vegetation classification-Africa, Sub-Saharan. SD536.6.A357E57 1994 33395'3911'0967-dc2O 93-23481 CIP Contents-

Preface and Acdnowledgments xi. Authors and Contributors xiii Acronyms and Abbreviations xiv

Part I Application of Remote Sensing for Woody Biomass Assessment and Mapping 1 Introduction and Background I 2 Using Meteorological Satellite Data for Vegetation and Land Use Mapping 5 RemoteSensing 5 Sensorsand Data Products 5 Advanced Very High ResolutionRadiometer (AvHR) Data 6 Normalized DifferenceVegetation Index (NDwvi)7 Vegetationand Land CoverMapping from NDviData 7 Production of NDviData by NASA,GSFC 8 3 lL pping of Land Cover Class 10 Phase I-Data Inspection and Preprocessing 10 Phase II-Initial Image InteIpretation 11 Phase I1-Automatic (Supervised) Classification and Mapping of Land Cover Classes 15 Land Cover Mapping 15 InterpretingAvHRRNDvIData for WoodyBiomass, Stock, and Sustainable Yield 16 4 Woody Biomass Assessment 19 Data Base for Biomass Estimation 19 Area Calculations of Land Cover Class 23 Interfacing Area Grouwng Stock and Data on Sustainable Yield 23 5 Description of Biomass Classes 24 6 Regional Summaries by Cass of Biomass 29 The West African Sahel 29 The West African Coast 31 The Hom of Africa 32 Central Africa 34 East Africa 35 Southern Africa 38 7 Condlusions and Future Directions 41 References .46

v vi Contents

Part II Regional Distribution of Land Cover Classes 8 The West African Sahel Richard W. Critchley 53 Class0-Desert 53 Class 12-Hydromorphic Grassland 54 Class 21-Semidesert Wooded Grassland 54 Class 44-Sahel-Sudanian AcaciaWooded Bushland 55 Class 62-Dry SudanianWoodland 56 Class 64-Sudanian Woodland 57 Class 65-Moist Sudanian Woodland 58 Land Cover ClassTables 59 References 59 9 The West African Coast Andrew C. Millington 64 Class 12-Hydromorphic Grassland 64 Class44-Sahel-Sudanian AcaciaWooded Bushland 64 Class 62-Dry Sudanian Woodland 65 Class 64-Sudanian Woodland 66 Class 65-Moist Sudanian Woodland 67 Class 74-Guinean Woodland 68 Overview:West African High Woody BiomassMosaics 71 Class 75-High-Productivity West AfricanCultivation andForestMosaic 71 Class 76-Medium-Productivity West AfricanCultivation and Forest Mosaic 73 Class 81-Mangrove 76 Land Cover ClassTables 77 References 78 10 The Hom of Africa John lrkby 85 Class O-Desert 85 Class 12-Hydromorphic Grassland 86 Class 13-Ethiopian Montane Steppe 86 Class21-Semidesert Wooded Grassland 87 Class 22-Acacia Wooded Grassland 88 Class 41-Dry Acacia-CommiphoraBushland and Tiket 89 Class43-Moist Acacia-CommiphoraBushand and Thicket 90 Class 44-Sahel-SudanianAcia Wooded Bushland 91 Class 45-Escarpment Wooded Thicket 92 Class52-East AfricanLow WoodyBiomass Mosaic 93 Class 62-Dry Sudanian Woodland 94 Class 63-Sudan-Ethiopian Woodland and Thicket 95 Class 64-Sudanian Woodland 95 Class 65-Moist SudanianWoodland 96 Class 73-Cultivation and ForestRegrowth Mosaic 97 Class 74-Guinean Woodland 97 Class 77-Highland CultivationMosaic 98 Class 84-Montane Forest 99 land Cover ClassTables 100 References 100 11 CentralAfrica Ternj D. Douglas 105 Class 11-Veld Grassland 105 Class 25-Edaphic Wooded Grassland 105 Class 62-Dry SudanianWoodland 106 Class64-Sudanian Woodland 107 Class 65-Moist Sudanian Woodland 107 - Class 66-SeasonalMiomboWoodland 108 Class 67-WetMiombo Woodland 108 Contents vii Class 72-Cultivation and Forest/Woodland Mosaic 109 Class 73-Cultivation and Forest Regrowth Mosaic 109 Class 74-Guinean Woodland 110 Class 82-Evergreen Forest 111 Class 85-Mesophilous Humid Tropical Forest III Class 86-Hunmid Tropical Swamp Forest 112 Class 87-OmbrophlUous Humid Tropical Forest 112 Land Cover Class Tables 123 References 113 12 -East Africa Phil O'Kfe,IanRyle,andJohnlCirkby 119 Class 0-Desert 119 Class 21-Semidesert Wooded Grassland 119 Class 24-Transitional Wooded Grassland 120 Class 33-Bushy Shnibland 121 Class 41-Dry Acacia-CommniphoraBuslland and Thicket 121 Class 43-Moist Acacia-CommiphomBushland and Thicket 122 Class 51-Acacia Woodland Mosaic 123 Class 52-East African Low Woody Biomass Mosaic 124 Class 61-Open Woodland 124 Class 65-Moist Sudanian Woodland 124 Class 66-Seasonal Aiombo Woodland 125 CLass67-WetMiomb Woodland 126 Class 71-Evergreen Woodland Moaic 127 Class 72-Cultivation and Forest/Woodland Mosaic 127 Class 73-Cultivation and Forest Regrowth Mosaic 128 Class 74-Guinean Woodland 128 Class 82-Evergreen Forest 128 Class 8-Coastal and Gallery Forest- 29 Class 85-Mesophilous Humid Tropical Forest 130 Class 84-Montane Forest; Class 86-Humid Tropical Swamp Forest; Class 87-Ombrophilous Humid Tropical Forest 130 Land Cover Class Tables 131 References 131 13 Southern Africa Roger Bevan 136 Class 0-Desert . 136 Class 11-Veld Grasslad 137 Class 14-Montane Grassland and Heatbland 138 Class 24-Transtonal Wooded Grassland 139 Class 31-Veld Shrubland and Cultivation 142 Class 32-Hill Shrubland 142 Class 33-Bushy Shrubland 143 Class 34-Kalahari Shrubland 144 Class 35-Wooded Shrubland 145 Class 42-Fynbas Thicket 146 Class 43-Moist Acacia-ComnziphomnBushland and Thicket 147 Cls 51-Acadza Woodland Mosaic 149 Class 61-Open Woodland 151 Class 66-SeanMwmbo Woodland (including Tropical Coastl Woodland) 154 Class 67-WetMiombo Woodland (icluding Warm Temperate Woodland) 158 .Class 71-Evergreen Woodland Mosaic 160 Class fl-Cultivation and Forest/Woodland Mosaic 162 Class 82-Evergreen Forest 163 Land Cover Cla Tables 165 References 165 viii Contents

Glossary 175 Index of Botanical Names 279 Index of Place Names 285 Figures 1-1 ProjectMethodology 4 -2-1 CharacteristicLand Cover ReflectanceCurves and Relationto AVHRRSensor Bandwidths 6 2-2 Small-Scaleand Large-ScalePerspectives of RadiationAbsorption and Reflection 8 2-3 RelationBetween NDVI and Above-GroundBiomass and VegetationCover 9 3-1 Distributionof Cloud Cover in 1986Imagery- 12 3-2 rcvi Profiles,Summary Land Cover Classes0, 1,, 13 3-3 NDviProfiles, Summary Land Cover Classes3,4, 5 14 3-4 Nrn Profiles,Summary Land Cover Classes6,7,8 14 3-5 RegionalSummary Land Cover Classes 17 7-1 Growing Stockfor Sub-SaharanAfrica, 1986 42 7-2 SustainableYield for Sub-SaharanAfrica 4 1986 43 8-1 NDVIProfile, Hydromorphic Grassland (Class 12) 54 8-2 NDVIProfile, Semidesert Wooded Grassland (Class21) 55 83 NDVIProfiles, Sahel-Sudanian Acacia Wooded Bushland (Class44) 56 B-4 NDcvProfiles, Sudanian Woodlands (Classes 62,64, and 65) 57 9-1 -vi Profiles,Sahel-Sudanianl Acacia Wooded Bushland(Class 44) 65 9-2 ,-wviProfiles, Sudanian Woodland (Class64) 66 9-3 -Dvi Profiles,GuineanWoodland (Class 74) 67 9-4 Nvi Profiles, High-ProductivityWest Afican Cultivation and Forest'.:.osaic(Class 75) .72 9-5 Cote d'Ivoire Wood Production,198D-84 73 9-6 C6te d'lvoire Wood Productionby Class,1980 73 9-7 C6te d'lvoire Wood Productionby Class,1984 73 9-8 Nvi Profiles,Medium-Productivity West African Cultivationand Forest Mosaic(Class 76) 75 9-9 Niv Profile,Mangrove. (Class; 81) 77 10-1 NwvProfiles, Bushland and Thicket(Classes 41,44, and 45) 89 10-2 NDVIProfile, SudamwianWoodland (Class 65) 96 10-3 NOWProfiles, High Woody BiomassMosaic (Classes 74 and 77) 98 10-4 NEWProfile, Montane Forest (Class 84) 99 11-1 NwmProffle, Edaphic Wooded Grassland (Clas 25) 106 11-2 NOvProfiles, Sudanian Woodland (Classes62,64, and 65) 106 11-3 NDviProfiles, Miombo Woodland (Classe 66 and 67) 108 11-4 NDviProfile, Cultivation and Forest RegrowthMosaic (Class 73) 110 11-5 NOviProfiles, Forests (Classes82,85, and 87) 111 12-1 NtVI Profiles,Bushland and Thicket (Classes41 and 43) 222 12-2 NDvxProfile, Seasonal Miombo Woodland (Class66) 125 12-3 NDviProfiles, High WoodyBiomass Mosaic (Classes 72 and 73) 127 12-4 NDonProfile, Evergreen Forest (Class82) 129 L3-1 NDviProfiles, Transitional Wooded Grassland (Class24) 139 13-2 NDvI Profiles,Shrubland (Classes 34 and 35) 144.- 13-3 NDviProfile, Moist Acacia-Commiphora Bushland and Thicket(Class 43) 147 L3-4 NDW Profile,Acacia Woodland Mosaic(Class 51) 150 13-5 NDviProfiles, Open Woodland (Class 61) 152 13-6 Nov Profiles,Seasonal Miombo Woodland (Class66) 154 13-7 Nov Profiles,Wet MiomboWoodland (Class67) 158 13-8 NDvw Profiles, Evergreen Woodland Mosaic (Clss 71) 161 13-9 NoviProfiles, Cultivation and Forest/WoodlandMosaic (Class 72) 263 13-10 MDvi Profiles,Evergreen Forest (Cla 82) 164

- : - . ~- . . Contents ix

Tables 1-1 Final Energy Consumption for AfricanCountries, 1980-88 1 1-2 Woodfuel Consumption in Sub-SaharanAfrica, 1990 2 1-3 MultistageStrategy for Woody BiomassResource Assessment 3 3-1 CloudCoverinl986lmagery 2! 3-2 Land Cover Classes for Sub-SaharanAfrica 16 4-1 Growing Stock and SustainableYield Data, 1953-90 21 6-1 Distributionof Summary Classesand EstimatedWoody Biomass,West African Sahel 29 6-2 Distributionof Summary Classesand EstimatedWoody Biomass,West African Coast 32 6-3 Distributionof Summary Classesand EstimatedWoody Biomass,Horn of Africa 32 6-4 Distributionof Summary Classesand EstimatedWoody Biomass,Central Africa 35 6-5 Distributionof Summary Classesand EstimatedWoody Biomass,East Afrca 36 6-6 Distributionof Summary Classesand EstimatedWoody Biomass,Southem Africa 38 8-1 Land Cover Classes-Burkina Faso (WestAfrican Sahel Region) 60 8-2 Land Cover ClassesChad (WestAfrican Sahel Region) 60 8-3 Land Cover Classes-The Gambia (WestAfrican Sahel Region) 61 --4 Land Cover Classes-Mai (WestAfrican SahelRegion) 61 8-5 Land Cover Classes-Mauritania (WestAfrican Sahel Region) 62 R-6 Land Cover Classes-Niger (WestAfrican Sahel Region) 62 B-7 Land Cover Classes-Senegal (WestAficain SahelRegion) 63 9-1 Areal Distribution,Dry Sudanian Woodland (62),West AfricanCoast Region 65 9-2 eAralDistnibution, Sudanian Woodland (64),West African CoastRegion 66 : 9-3 Areal Distrnbution,Moist Sudanian Woodland (65),West African CoastRegion 68 9-4 Areal Distribution,Guinean Woodland (74),West AfricanCoast Region 68 9-5 Woody BiomassStocks and Growth Rates,Guinean Woodland Conmmunities,Lamto, Cote d'Ivoire 69 - 0 9-6a Meal Distnbution, High-ProductivityCultivation and Forest Mosaic(75), West African Coast Region. 71 9-6b Areal Distribution,Medium-Productivity Cultivation and Forest Mosaic(76), West African Coast Region 71 9-7 Equivalent Names for Cultivationand Forest Mosaicin West AfricanCoast Region 74 .9-8 Degree of Deciduousness,Reserved Moist Forests, Sierra Leone 74 9-9 Land Cover Classes-Benin (WestAfrican Coast Region) 80 9-10 Land Cover Classes-Ghana (WestAfrican CoastRegion) 80 9-11 Land Cover Classes-Guinea-Bissau (WestAfrican Coast Region) 81 9-12 Land CoverClasses-Guinea (WestAfrican Coast Region) 81 9-13 Land Cover Classes-COte dIvoire (WestAfrican Coast Region) 82 9-14 Land Cover Classes-Liberia (West AfricanCoast Region) 82 9-15 Land Cover Classes-Nigeia (WestAfrican Coast Region) 83 9-16 Land Cover Classes-Sierra Leone (WestAfrican Coast Region) 83 9-17 Land Cover Classes-Togo (WestAfrican Coast Region) 84 10-1 Land Cover Classes-Djlbouti (Hom of AfricaRegion) 102 10-2 Land Cover Classes-Ethiopia (Hom of Africa Region) 102 -. 10-3 Land Cover Classes-Somalia (Horn of AfricaRegion) 103 10-4 Land Cover Classes-Sudan (Hom of AfricaRegion) 704 11-1 Land Cover Classes-Cameroon (CentralAfrica Region) 115 11-2 Land Cover Classes-Central AfricanRepublic (Central Africa Region) 116 . .: - 11-3 Land Cover Classes-Congo (CentralAfrica Region) 116 -11-4 Land Cover Classes-Equatorial Guinea (ainland; CentralAfrica Region) 117 11-5 Land Cover Classes-Gabon (CentralAfrica Region) 117 11-6 Land Cover Classes-Zaire (CentralAfrica Region) 118 12-1 Land Cover Classes-Burundi (EastAfrica Region) 132 x Contes---

12-2 Land Cover ClIsses-Kenya (EastAfrica Region) 132 12-3 Land Cover Classes-Rwanda (EastAfrica Region) 133 12-4 Land Cover Classes-Tanzania (EastAfrica Region) 234 12-5 Land Cover Classes-Uganda (EastAfrica Region) 135 13-1 Land Cover Classes-Angola (SouthernAfrica Region) 167 13-2 Land Cover Classes-Botswana (SouthernAfrica Region) 168 13-3 Land Cover Classes-Lesotho (SouthemAfrica Region) 168 13-4 Land Cover Classes-Malawi (SouthemAfrica Region) 269 13-5 Land Cover Classes-Mozambique (SouthernAfrica Region) 170: 13-6 Land Cover Cl_sses-Namibia (SouthernAfrica Region) 171 13-7 Land Cover Classes-South Africa(Southern Africa Region) 172 13-8 Land Cover Classes-Swaziland (SouthemAfrica Region) 173 13-9 Land Cover Classes-Zambia (SouthernAfrica Region) 173 13-10 Land Cover Classes-Zimbabwe (SouthemAfrica Region) 174

Maps (at end of book) Legend for RegionalLand Cover ClassMaps RegionalLand Cover ClassMap of West Africa RegionalLand Cover ClassMap of East Africa RegionalLand Cover ClassMap of Central Africa RegionalLand Cover ClassMap of Southem Africa

- -. - Prefaceand Acknowledgments

Woodfuels play a dominant role in the energy balance John Kirkby, Richard Critchley, and Anthony Mellor. of countries in Sub-Saharan Africa, and shortages of Jon Styles' participation was made possible through a woodfuel exist-or are perceived to exist-in many leave of absence from research training granted by the areas. This volume describes a first attempt to map the Natural Environment Research Council (U.K). Man- varied vegetation and types of land cover in Sub- agement and administration of the project were led by Saharan Africa and to assess the growing stock and Phil O'Keefe of mrc(U.K). sustainable'yield of woody biomass. It is the result of As a first step, it was decided to conduct a conti- a project undertaken by the Energy Sector Manage- nental overview of woody biomass in the region, nent Assistance Programme (Esmu",a joint program from Advanced Very High Resolution Radiometry of the World Bank and the United Nations Develop- (Avhln) data obtained by satelite. Instrumental in m- ni Programme) to address the lack of data on en- this initial stage were the help of Jim Tucker, who erg -resources for most African countries. This infor- permitted access to data at the U.S. National Aero- mation is essential for calculating energy balances. nautics and Space Administration's Goddard Space The work's usefulness, however, goes far beyond Flight Center, and John Townshend, then director of questions of energy sufficiency. Appropriate manage- the Unit for Thematic Information Services at the Nat- ment of Africa's biological resources, to which it is ural Environment Research Councila University of hoped this work will contribute, will help maintain Readin& who provided computational facilities for and perhaps enhance environmental quality on the data interpretation. continent. Moreover, the extent of worldwide forest Drafts of the maps and the project report were cover has come to be recogimzed as a critical variable presented at workshops in Nairobi, Kenya, and in predicting global climate change. Together these Abidjan, C6te d'Ivoire, in May 1989. An important considerations make the assessment of existing wood part of the collective workwas the peer review led and resources in Africa a timely intervention. - conducted by senior African scholars and profession- The impetus for this project came from an ESMAP als at these meetings. These individuals incLuded Household Energy Seminar held in Harare, Zim- Jean-Marie Ouadba and Cyrille. Kabore (Burkina babwe, in February 1988. Energy and forestry officials Faso), Benedict Fultang (Cameroon), Dieudonne attending the seminar reached the conclusion that Dzimasse (Central African Republic), Me Kouame, data on African woodfuel resources, needed as a basic N'Zore Kadja, Jean-Claude Anoh, and Aidara tool for the planning of woodfuel programs, were in Gouesse Largeni (C6te d'Ivoire), Waldikidan Nere short supply. With generous funding provided by the and Sultan Tilmo (Ethiopia), Kingsley Ghartey and government of the Netherlands, the mapping of Afri- Gamphi-Aidoo (Ghana), J. Gore, J. Mutie, P. Waciori, can land cover and assessment of its woody biomass H. Mwendwa, and J. Agatsiva (Kenya), Antonio that are the basis of this book were undertaken by nrc Ferrio (Mozambique), Issa Boubacar (Niger), Reg. (UK), under the supervision of Paul Ryan of ESmA. Cine-Cole (Nigena), Isatu Deen (SierraLeone), Ismael The project, which got under way in July 1988,.was Grammadid(Somalia),MustafaElHaqandMohamed a collective effort between a team at the University of Elrady (Sudan), Idris Kikula. and Edward Mlowe Reading, led by Andrew C Mllington and consisting (Tanzania), David Siamuele (Zambia), Peter Gondo of Jon Styles, Richard Saull, Pam Kennedy, and Nick (Zimbabwe), B. K Kaale (Southern African Develop- Drake; and a team at the University of Northumbria, ment Community), and Barry Henrilson (Regional led by Terry Douglas and consisting of Roger Bevan, Remote Sensing Centre, Nairobi). Their local knowl- -.~~x xli Prfacc nd Aclcnowlcdgments edge of vegetation and woody biomassstatistics was achievedits objectives.Although the accuracy of the crucial to the project's success. As a result of their assessmentis limitedby the resolutionof the satellite critiques, we were able to refine the maps and the images and by the paucity of existingdata on woody vegetation typing. biomass In the various vegetation types, the study Thanks also are extended to the librarians,particu- resultedinaveryusefulmappingreference. Itnot only larly at the World Bank in Washington,D.C., and the provides sufficient information on woody biomnss Food andAgricultureOrganization(PAo)oftheUnited resources to enable broad policy and pldnning deci- Nations, who diligently pursued our bibliographic sions regarding woodfuel management but also inquiriesbeyond the normal call of duty. should help researchers investigatingbroader issues Thanks are due also to Gary Haley of the University such as the contribution of caibon sequestering by of Northumbria, who prepared all of themaps, and to living plants to the mitigation of global greenhouse Joalle Hivonnet, translator for the French edition of warming.Webelieve this collectiveeffort tobe a small this volume. step toward understanding, maintaining,and enhan- Revised maps and the final report were presented cing Africa'swood resources,on which so many peo- to ESMAPin January 1990.It is fair to say that the project ple depend for their well-being.

. . . . .~~~~~~~~~~~~~~~~~~~~~~~ Authors and Contributors

Andrew C Millington, read- m the Department of Geography, University of Reading (UK) Richard W. Critczley, senior lecturer in Ecology, Department of Environment, University of Northumbnria at Newcastle (U.K) Ternr D. Douglas,principal lecturer in Environmental Management, Department of Environment, University of Northumbria at Newcastle (U.K) Paul Ryan,aforestryspecialistwitltheEnergySectorManagementAssistanceProgramme (Ems&), ajointprogram of the World Bank and the United Nations

Contributors

Roger Bryan, senior lecturer in the Department of Environment, University of Northumbria at Newcastle (U.K.) John Mirkby,senior lecturer in the Department of Environment, University of Noithumbria at Newcastle (U.K.) Phil O'Keefe,professor in the Department of Environment, University of Northumbria at Ne-wcastle (U.CK) Ian Ryle, Education and Trairiing Consultants (U.K)

xiii Acronyms and Abbreviations

AErFAT Association pour 1'Etude Taxonomique. . Leaf Area Index de la Flore de 1"AfriqueTropicale NASA/GSPC National Aeronautics and Space AVHRR Advanced Very High Resolution Administration/GoddardSpace Radiometer Flight Center CAR Central Afric.n Republic NDVI Normalized Difference Vegetation ccr Computer compatible tape Index cPU Central processing umit NOAA National Oceanic and Atmospheric cinr Centre Technique Forestier Tropicale. Administration DN Digital number - c (Natural Envirorunent Research rERs Earth Resource Satellite Council) Unit for Thematic ESmr - Energy Sector Management Assistance InformationServices Programme (of the World Bank rso Polar Stereographic Projection and theuNDP) SADC Southern African Development EFc(Tuy-) Education and Training Consultants Community (formerly sDcc, South- FAo0 . - Food and Agriculture Organition em African Development Coordina- of the United Nations tion Conference) GAc Global Area Coverage SMLMfR ScanningMultichannelMicrowave. GE Geographic information system Radiometer cv Global Vegetation Index SPOT Satellite pour l'Observation de la Terre HRFr High Resolution Picture Transmission ToE Tonnes of energy equivalent -ED International Institute. for Environment (metric tons) and Development UNDP United Nations Development MNR Institut de Recherche Agronomique Programme . du Niger. UNMo United Nations Educational, Scientific, IRET Institut de Recherche en Biologie and Cultural Organization et Ecologie Tropicale WARDA WestAfricanRiceDevelopment LAC Local Area Coverage Association

. ~~ ~ . ~ i . .

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xiv PART I

Application of Remote Sensing for Woody Biomass Assessment- and Mapping Introduction andBackground

Woody bionmassconstitutes the main domestic fuel in present in Sub-Saharan Africa. The project was con- many parts of Africa. The need for more defintive ducted byErcouc.) under the auspices and supervision data on this resource was perceived at a Household of ESMAP,ajoint program of the World Bank and UNDP EnergySeminarheldbytheWorldBankEnergySector (United Nations Development Programme). Management Assistance Pogamme (Emw) in Harare, On examining the energy balance for most Sub- Zimbabwe, in February 1988. The present project was Saharan countries, one is struck by the domiinance of conceived as a resulL It is a first attempt to produce an woodfuel, induding fuelwood and charcoaL This is analysis by type of land cover of the woody biomass well illustrated in table 1-1, which shows that wood-

Table 1-L Fnal EnerConsumption for African Countnes, 1980488 (pent) -- - Woodfideland a-ldgrigdhraland Total Country Petrolum Cokeor coal Ekltrik4 bmass residue (1,000 TeE) Year Benin 12.5 0.0 s15 86.0 853 1982 Botswana 28.0 15.0 8.0 49.0 853 1988 Congo 49.0 - 0.0 4.7 46.3 574 1985 Coted'lvoire 31.1 0.0 5.1 63.8 2764 -1982 Ethiopia 9.7 0.0 1.4 88.9 10,905 1982 Gabon 73.1 0.n 10.5 16.4 619 1985 The Gambia 25.4 0.0 1.7 72.9 174 1982 Ghana 23.0 0.0 3.0' 74.0 3,100 1985 Liberia 22.7 0.0 8.6 68.7 918 1983 Malawi 13.0 4.0 6.0 77.0 3,389 1980 Mozambique 9.7 02 1.6 88.5 3,170 1984 Niger 12.0 0.0 2.2 85.8 964 1981 Nigeria 56.3 0.6 3.0 40.1 18,700 1981 Rwanda 8.7 0.0 2.3 89.0 1,129 1987 Senegal 32.8 0.0 2.8 64A 1,679 1987 SierraLeone 13.0 0.0 2.1 84.9 911 1984 Somalia 11.8 0.0 1.2 87.0 1,123 1984 Sudan 17.5 0.0 1.1 81.4 5,606 1984 Swaziland 22.7 19.0 7.7 50.6 595 1985 Tanzania 7.4 0.0 0.6 92.0 9,025 1981 Togo 47.0 0.0 13.0 40.0 214 1982 Zambia 13.0 8.0 13.0 66.0 4,233 1988 Zinbabwe 17.1 24.8 15.1 43.0 4,832 1988 Weighted average 25.6 2.7 4.0 67.8 a. Inmany countriesdataare ladcingonthe quantityofagricultuiresidues consumedInless-and climatesthis may amomnttolittle,but inwoodel-poorSaheliancountries it couldattain 10percentof total energy mnsumption. * SourcS: uNmP/WorldBar&kEnergySedor a--essments. = . . .~~~~~~~~~~~~~~ 2 Estinating WoodyBiomass int Sub-Sahmn Afica fuel and agricultural residue represent 67.8percent of 1-2). Assessment of woodfuel supply, however, has the final energy consumption on a weighted average not been undertaken in most countries. Further, spa- basis. The dominance of woodfuel is principaily re- tial extrapolation from the limited reliable data that lated to households, in which the most important use exist is fraught with ecological and environmental is cooking. Woodfuel, however, also is important for interpretive problems. rural and small industries such as tobacco curin& tea Without reliable data on the growing stock and, drying, fish smoking,beerbrewing,brickmaking,and more important, on the sustainable yield of woody commercial balidng. biomass, it is not possible to prepare mnearingful woo d- Accurate estimates of household energy consump- fuel development and conservation plans within tion and overall woodfuel consumption are not avail- an overall energy strategy. Unfortunately, some pro- able for many Africancountries. Limited surveyshave grams and projects have been designed and im- been conducted, enablingestimation of woodfuel con- plemented without defining the sustainability of the sumption in conjunction with demographic data (table woodfuel resource in relation to current and pro-

Table 1-2. Woodfuel Consumption in Sub-Saharan Africa, 1990 (millionair-drytonnes) Region Country Consumption R-egionaltotal West AfricanSahel BurkinaFaso 4.3 17.8 Chad 2.5 The Gambia Mali 3.7 Mauritania 0.8 Niger 23 Senegal 42 West African Coast Bendin 23 813 C8te d'Ivoire 62 Ghana 8.6 Guinea 2.9 Guinea-Bissau 03 Liberia 3.9 Nigeria 513 Sierra Leone .3.0 Togo 2.8 Hom of Africa Ethiopia 135 31.4 Somalia 3.3 Sudan 14.6 CentmalAfrica Cameroon 7.4 403 Central Afican Republic 2.6 Congo 1.1 Gabon 1.8 Zaire 274 East Africa BurUkdi 17 82.5 Kenya 25.3 Rwanda 3.6 Tanzania 34.9 Uganda 17.0 Southern Africa Angola 3.1 44.9 Botswana 12 Lesotho 0.6 Malawi 102 Mozambique 11.1 SouthAfrica 52 Swaziland 0.4 Zambia 6.8 Zimbabwe 63

- Not available- Sourc uwar/World BankEnergy Sector assessments. Introductionand Bnckground 3

Iected consumption, including potential-changes in Bothestinationrmethodsfailtoconsiderbiomasson consumption. farms and around villages. This is a significant limita- Estimatesof woodybiomass derived from field data don in the use of such data for energy planning, be- can be divided into two groups, the classical forest cause recent studies have indicated the importance of inventory and estimates of above-ground woody bio- wood produced on farmland (Munslow and others mass. In the classical forest inventory, methodologies -1989). used by foresters have generally concentrated on com- In this book we describe the initial stages of a mul- mercial wood in high forests. Consequently, estimates tistage mapping and assessment strategy for produc- have focused on the stem volume of potentially com- ing estimates of growing stock and sustainable yield mercial species and within commercial size limits. of woody biomass in Sub-Saharan Africa (table 1-3). Such estimates neglect important sources of woodfuel To achieve this we created a data base of the existing such as branches, twigs, dead wood, woody under-- woody biomass estimates just described and extrapo- growth, shrubs, and noncommercial tree species.These lated these data in a framework of spatial land cover. mensuration estimates give little indication of woody The framework derived from remotely sensed data at biomass stocks and productivity in forest areas, yet a contnental scale. The stages of this methodology are these areas, particularly woodlands, are a principal shown in figure 1-1. woodfuel source in much of Africa. Clearly,only two types of data can be used to map Estimates of above-ground woody biomass are more the woody biomass resource at- this scale: existing useful and have been made in some parts of Africa. maps and remotely sensed data. A compilation of Despite their greater application potential for energy previously published maps would have provided an planning, considerably fewer of these studies have unsatisfactory product for three reasons: the age of been conducted compared with forest inventories, and the maps in relation to the dynamic vegetation and they are restricted mainly to semiarid areas. land cover; the variation in scale of mapping; and the

Table 1-3. Multistage Strategy for Woody Biomass Resource Assessment Reviewof ExistingDab and Maps for Area

Low-Spatial-Resolution Satellite Imagery * AdvancedVery HighResolutionRadiometer(AYHR) * Resolution: 1.1 to 15 kilometers * Environment large country or multicountry region * Supported by limited ground verification and existing environmental data * Provides 1:5,000,000-scalemaps with broad land cover zones

High-Spatial-ResolutionSateitel Iagery a Landsat Multspectral Scanning System (mm),resolution 79 meters * Landsat Thematic Mapper (iu), resolution 30 meters * spar (Satellite pour l'Observation de la Terre) High-Resolution Visible (nv) multispectral, resolution 20 meters * Envirornment small country or portion of a country * Supported by ground verification, aerial photography, airbome video imagery, and existing data onbiomass estirates * Provides 1:250,000-to-1:1,000,000-scalemaps with more detailed land cover types

Biomass Reconnaissance Inventory * s orHRv(panchromatic) or aerial photography, or both * Low-intensity inventory, perhaps with subplots for smaller vegetation types * Supported by cartographic or image maps and established regressions and correlations between measurable para- .metersand biomass * Destructive sampling to establish regressions * May include nonforest as well as forest areas

Biomass Management Inventory * High-intensity inventory wvithsubplots supportedby maps in forest and nonforest areas

Conversionof IndustrialWood Volumes to TotalAbove-Ground Biomass * Supported by maps or aerial photography, orboth, and established regressions and correlations between industrial wood volume and total biomass Note Elementsare not rsarily in sequentialorder. 4 EstitratingWoody Biomass in Sub-SoharantAfrica

Figure 1-1. Project Methodology

|Remotdelysensed|-. tt dwa~~~~~~~~~~~~~~~~~~~~~~~~~~dt

- >Analysisof remolely =uetseddata

- I Promsionalland Datbase | covcrclassnmaps elpment

w IdentudScionh orurldis an- S

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Lancdvery Highs Repsolto Raioetr(Au ata, cors,t wsdcddt s heAHRdtrm18

whichaspatil ith resoutionof 8ilomeers w vere forkthiswr fteveeaindt frln oe

approptcriaterfor this proecthebss fobjctvmoft mappingu mappingulthatinwtbeca enavitsabltfo theNaVHRRa Aeron-

land cover. For other studies, such data. have been ery beginning in 1981, the data for 1986 appear to be used successfully to map land cover at the continental thebest quality forarelativelynornalrainfail year over scale in Africa (Townshend and Tucker 1984) and most of Africa. The use of a single year's data leads to Latin America (Townshend, justice, and Kalb 1987), certain problems, which will be addressed later, and and the woody biomass resource in southern Africa the maps produced represent only asituational ov.er-., (Millirngton and others 1989). view of the woody biomass resource for 1986. 2 Using MeteorologicalSatellite Data for Vegetation and Land Use Mapping

In this chapter we define remote sensing, stressing its Sensors and Data Products application to the mapping and monitoring of vegeta- tion. We describe the main satellites and sensors, dif- Sensors for the acquisition of remotely sensed data are ferentiate between Earth resource satellites and mete- mounted on board various satellites. These satellites orological satellites, and discuss the nature of digital can be broadly grouped by function into Earth re- imagerv. We then examine in detail the Advanced source satellites and meteorological satellites. Earth Very High Resolution Radiometer (AvHmR),the use of resource satellites include the American Landsat Normalized Difference Vegetation Index (Ntw) for series, the French spor satellite, the European Space land cover mapping and vegetation monitoring, and Agency's Es-i, and the Indian Space Agency's *RS-x. the production of Nvimfor this project Meteorological satellites include those of the National Oceanographic and Atnospheric Administration (NOAA) Remote Sensing and the European Space Agency's METOSAT.The roster of operational satellite-sensor combinations constantly Satellite remote sensing is the technique of acquiring changes; contemporaneous reviews are available in data (imagery) that describe the Eart's surface and Cracknell and Hayes (1991)and in Drury (1990). atmospherewith the use of satellites. Sensors on board -Data are available either as photographic (optical) satellites provide data at a synoptic scale from a single products or as computer compatible tape (ocr). The image acquisition, thereby making the analysis of re- ccr often is more useful for resource assessment be- motely sensed data a cost-effective tool for resource cause it can be digitally processed to optimize the assessment over large areas. information that can be extracted. Such digital image A further advantage of satellite data is that repeat processing can be carried out effectively only with a imagery for any scene usually can be acquired. The computer-basedimage-processingsystem-Interpreta- repeatperiodbetween imageacquisitions varies from tion of photographic products is limnitedbecause data less than 24 hours for meteorological satellites to be- cannot be manipulated to highlight particular aspects tween 16 and 26 days for Earth resource satellites. The of the image. In some cases, however, photographic repeat period can be much longer for Earth resource prints provide adequate results. satellites (for example, 18 days for Landsat-4 and Sensors cover the ultraviolet, visible, infrared, and Landsat-5) for various technical and logistical rea- microwave portions of the electromagnetic spectrum. sons. The capability to provide time-sequential data The Earths atmospheric gases act as "windows" to is of great advantage in both biomass resource as- allow the tiansmission of radiation of specific wave- sessment and monitoring because of the relatively lengths, and satellite sensors are constructed to corre- rapid response of plants to changes in the weather, spond to these windows, maximizing reception of the climatic seasonality, changing climates, and other radiation reflected or emitted from the Earths surifce disturbances. Sensors, however, are not built to cover all the avail-

5~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 6 Estimating Woody Biomassin Sub-SaharunAfrica able windows between ultraviolet and microwave Figure 2-L Characteristic land Cover Reflectance wavelengths. Although it would be valuable for bio- Curves and Relation to AVHRR Sensor Bandwidths mass assessment to have a sensor covering the electro- magnetic spectrum from ultraviolet through micro- - 2 wave, thus permitting the simultaneous sensing of all Bnndidth of chans 1 and 2 radiation and absorption features, this is not possible onAVHRR sensor for technical reasons. This situation should improve Healthy with the anticipated launching of mulfisensor plat- vtatio r - - - - forms in the mid-to-late 1990s. _-O' Biomass resource assessment using remotely sensed soil ----. data mainly concerns the interaction of electromag- I netic radiation with the vegetation canopy. Radiation ~ ! _,.L-- - of all wavelengts interacts with this canopy, if one is ' present, and at any wavelength the radiation is either ¢---- J: Stressed or sneseon absorbed, reflected, or emitted. In addition, if the veg- x_I etation canopy does not completely cover the ground, Watcr some interaction between radiation and the ground surface will occur. To understand how these interactions affect bio- 4 w 6w 700 wo gw 1000 110 mass assessment and mapping, the concept of scale Blue Gaza Rd Mearinfd must be considered. At the scale of arn indidual leaf, radiation interacts with the cells in each leaf of a plant. Although examIiinationof individual leaves does not provide information of direct relevance to a biomass Detailed studies relating the physiology and bio- survey, this information is fundamental to understand- chemistry of plants to their spectral characteristics has ing the reflectance from vegetation. Of more direct been undertaken (for example, Sellers 1985, 1986; relevance is the interaction of radiation with all ele- Tucker and Sellers 1986). These studies conclude that ments of a vegetation canopy and with any soil ex- spectralreflectanceofvegetationisIelatedto thephys- posed through the canopy. It is this kind of interven- iological processes that drive plant growth, namely, tion that occurs at the spatial scale of most sateUite photosynthesis and respiatiorL remotely sensed data and therefore an understanding Shiftng our perspective from the scale of a single of it is relevant to the types of measurements made by- leaf to the scale of a vegetation canopy, it is dear that sensors on board satellites. radiation is reflected fromboth the vegetation and the It is possible to measure the proportion of radiation underlying soil (figure 2-2, bottom). Sensors for both reflected at a particular wavelength and to derive a parts of the spectrum, 0.6 to 0.7 Pm and 0.8 to 1.1 pm,l characteristic curve for green vegetation or a particu- are used in most Earth resource and meteorological lar land cover type. Such curves can be quite distinct sateites. (figure 2-1), but the precise nature of a vegetation curve or land cover curve varies according to the type Advanced Very High Resolution Radiometer of vegetation, the time of year with respect to plant (AvHn) Data development, whether the plant is stressed, and the completeness of the vegetation canopy-that is, how The data used in this work were acquired by the much reflection occurs from the soil surface : Advanced Very High Resolution Radiometer The spectral characteristics of vegetation reflectance (AvIu), a sensor carried on board the American are such that remotely sensed data are most useful for NOAAseries of meteorological satellites. Data mapping and monitoring of vegetation and land use derived from the AVIER imagery were supplied in when they are acquired in the visible red and near- ccr format by the National Aeronautics and Space infrared regions of the spectrum. In the visible red Administration/Goddard Space Flight Center region (0.6 to 0.7 micrometer or pm), radiation is ab- (NASA/GSFC). sorbed by chloroplasts for use in photosynthesis. This Of six NOAA satellites launched between 1979 and contrasts with the strong reflection of near-infrared 1988, two remain operational: NoAAj-io,launched Octo- radiation that is used for sensing vegetation (0.8 to 1.1 ber 1986, and NOAA-i, launched September 1988.The pm); it is caused by reflection and refraction from leaf AvHR sensors on board each satellite. have the follow- cells (figure 2-2, top). ing spectral channels UsingMeteorologicalSatelliteDala7

Wavelengthnrnge, equation dimninishesatmospheric effects. The NDVI iS Channel zipperto lower(grm) produced routinely by NAsA/G5srCand is calculated 1 0.58-0.68 by: 2 0.725-1.10 a 3.55-3.93 NDVI - DN(Channel2); -DN (Channell)i 4 10-30-12.50 DN (Channel2)i + oN (Channell)j. 5 11.50-12.50 whereoN is the digitalnumberrepresentingthereflec- Each satellitehas an average orbital elevation of 833 tance from channel n for the ith pixel. kdlometers and a period of 102 minutes, affording complete coverage of the Earth's surface every 9 days. Vegetation and Land Cover Mapping Ground coverage is an area of 2,700 Iclometers, with from NDvi Data a ground resolution of 1.1 kilometers at nadir. Data are acquired for any part of the Earth's surface Since 1981 a number of researchers have taken advan- by the AviR sensor oanboardeach NoAAsatellite every tage of such ecological data from meteorological sat- .12 hours. Il every 24-hour period, an image for a. elites for mapping of vegetation and land cover over specific area is acquired once dunng daylight and large areas. These indude Danaher and others (1992); once during the night For example, at the equator, the Eidenshink and Haas (1992); Gatlin, Sullivan,. and local time of image acquisition for NOAA-9 was 1430 and Tucker (1983);Goward, Tucker, and Dye (1985);Gray for motAA4owas 0730. . and McCrary (1981); Koomanoff (1989); Norwine and For work on vegetation mapping only the daytime rGreegor (1983); Schneider, McGinnis, and Gatlin imagery is used because it reflects the interaction be- (1981); Tarpley, Schneider, and Money (1984); tween incoming solar radiation and the vegetation Townshend and Tucker (1984);Townshend and oth- that is the basis for differentiating vegetation types, ers (1991);Tucker, Holben, and. Goff (1984); Tucker, cover, and status. The daily times quoted here are Gadin, and Schneider (1984). This body of work has those when the polar-orbiting NOAAsatellites cross the led to a number of natural resource applications in the equator. These times,.however, become later during tropics, includingv the life of each satellite because of orbital drift, affect- ing the overall reflectance. Gutman (1991) offers fur- * Monitoring Lake Chad (Schneider, McGinnis, and ther discussion of this. Stephens 1985) The short time interval between daily acquisitions * Mapping biomass production for grazing in Sene- of imagery creates a high probability that a pixel or gal (Tucker and others 1985) ground resolution element (the area of Earth's surface - Monitoring semiarid rangeland in Africa (Prince viewed by the sensor at any time during its scan) will 1986, 1991; Diallo and others 1991; Franklin and be free of clouds. Hiernaux 1991; Justice and Hiemaux 1986; Prince and Tucker 1986) Normalized Difference Vegetation Index * Monitoring semixaridrangeland in Australia (Bar- (Nnvi) ber 1992; Flemons 1992) * Monitoring cropping patterns in Southeast Asia In the absence of clouds, the AvHR sensors, particu- (Malingreau 1986) lar .y those for Channel 1 (0.58 to 6.8 tm)and.Channel * Assessing the woody biomass resource for wood 2 (725 to 1.10 pm), will sense vegetation, bare ground, energyplanninginsouthemAfrica (Millingtonand or open water. Consequently, useful ecological infor- others 1989) mation can be obtained about land surfaces- This in- * Drought early warning systems (Hendrickson and formation enables calculation of an index of vegeta- Durkin 1986) tion stacus for each ground resolution element A * Droughtmonitoringin Australia (Brook and others vegetation index is derived to reduce measurements 1992) of the vegetation canopy, ground cover, and biomass * Vegetation management in Australia (Roderick and to a single number (Perry and Lautenschlager 1984). Smith 1992) Many different vegetation indices are available to * Monitoring tropical deforestation in Amazonia scientists who use remotely sensed data, but the Nor- (Malingreau and Tucker 1987) malized Difference Vegetation Index (NDvi)has been * Monitoring land cove:' changes associated with used successfully and extensively with AvHRRdata desertification in Palkstan (Saull, Mllington, and principally because the nornalizing nature of the Crosettil991). 8 EstimatingWoody Biomass in Sub-SaoaranAfrica

Figure 2-2. Small-Scale and Large-Scale Perspectives of Radiation Absorption and Reflection

Near-infrared Visible red (0.-1.1 pm) (0.6-0.7pm)

- . - . / /C~~~~~~~~~~~~~~~hloroplasts

Upper-epidermnis ------PalisadecelLs]iTh I3 ; 19.-. tI UUx

Spongy nesophyll Leafcross-section

Lower epidermnis CC=0 D C-Z

Reflectionand absorptionof visible red and near-infraredradiation in part of a single leaf

Radiationpathways in an open canopy typical of zavannawoodlands

resolutions, Some studies have correlated theNv with biomass The NDVIis available at different spatial parameters such as above-ground biomnass (figure 2-3, includin& for example: left) and vegetation cover (figure 2-3, lower right). is known Althcaghnone of the studies relates specifically to tree Nwviat a spatial resolution of 8 kilometers 1991). or shrub biomass, they do suggest that similar core- as the Global Vegetation Index (GVI)(Tarpley kilometes reso- lations should be discovered for woody biomass. These data also are available at 15 lution after resampling to a polar stereographic Production of NOvi Data by NASAIGSFC projection. NUVIat a spatial resolution of 4 kilometers is known Early mapping of vegetation carried out using AVHY} as Global Area Coverage (G;AC)data. is derivedNrvrdataso vividlyillustratedthepotentialof * NDv at a spatial resolution of 1.1 kilometers data or High these data that the NDviis now routinely calculated by ]known as Local Area Coverage (LAC) data, de- NAsA/GsrcandtheFoodandAgricultureOrganization Resolution Picture Transmission (wrT) by a of the United Nations (FAo), using the above equation pending onhow it is obtained. If it is obtained Using MeteorologicalSatellite Data 9

Figure 2-3. Relation Between NVVI and Above-Ground Biomass and Vegetation Cover

3000

2000 .

02- /0 I * Correlationcoefficient . 0..49 a*

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groundreeivn gtainneatmiisnwa,pxl ihdusprocsd NDn)rpeettedentre This h-asbeeno aclcowleded to6)work X - . R f. : - . - HnT data.IfitimgsobaineidbfeyoEngd te radioiznf welloedurep- areducs: where thin afromdthe- :~~~~~~~~~~~~~~~~~~~~~~ areospreve- .. @ ,., 4. -;-M- .- . . 4 0 2 recodersand thluentransmittedt sthegrsoun whnayi weresendsountre withdouds uaionth fdtahuedvegetatis -Etio;iis, then kndxownasLA tempoa. dailykemm data areacopsie ovr1-aitras

(ta is th rdco f tepoa copsie of th ne 3~~~~~~~~~~~~~~~~~~~~~~~~~

Mapping of Land CoverClass

To identify and map classes of land cover, we interpre- data. In the data set used for this work, errors involved. ted Normalized Difference Vegetation Index (NDvi) only individual pixels. We constructed a digital filter digital data derived from the Advanced Very High to solve the problem of empty single pixels. The filter Resolution Radiometer (AvHi). -The work was per- was a modified 3 x 3 pixel average filter that replaced formed in three phases: any pixel which fetl outside the range of possible DN (digital number) values (120to 210) with the average Phase I Data inspection and preprocessing of the DN values of its eightneighboring pixels. A pixel Phase II Iitial image interpretation, derivation of alsowasreplacedifitfellwithinthisrangebutthesum the NDvi temporal profiles (Nrovphenolog- of the differences between the pixel and its neighbors ies), provisional mapping of land cover exceeded a certain threshold. This was done so that all casses, and limited field verification of -images that subsequently were processed would not provisional maps of land cover dass have any pixels that lacked data. Phase III Automatic classification and mapping of Larger areas that -lacked data entirely also were land cover classes. observed in the imagery. These occurred in areas where cloud cover persisted during the imaging periods and The followingsections describe the equipment, data meant that, during some months, no pixels free of specifications, errors, preprocessing, identification of clouds could be found from which to calculate the land cover classes, mapping, and interpretation of the NDVI. These areas did not occur in every month of the - mvrdata. year at a particular location, but because a continuous sequence of months is needed to define land cover Phase I-Data Inspection and Preprocessing classes, the presence of cloud in pixels clearly could affect the accuracy of the final land cover map. These All image processing was undertaken on mainframe problem areas occurred mainly in the coastal humid and microcomputer-based image-processing systems tropics, in the high mountains of eastem and central at the University of Reading. The image data initially Africa, around Lake Chad, and in the vicinity of Table wereevaluatedon-screen,andhardcopyimagerywas Mountain in South Africa. produced for intermediate stages of the interpretation The smaller areas of cloud were eliminated after process and for field verification, - classification (compare with Phase IIl) using an itera- Global Vegetation Index (GVI)data at 8 kilometers tive median-ffitering method. The original NDvidata spatial.resolution for 1986were provided byNAsmAGsFc and the filtered data then were combined using a for 10-day and monthly intervals. These data were logical or operation, so that the original data were registered to one another and were provided on the altered only when a zero value (cloud) occurred in the Hammer-Aitoff Conic Equal Area Projection. Initial original data. Some very large areas of cloud, how- inspection of these data disclosed two types of errors: ever, could not be eliminated entirely by filtering; pixels lacling NDvivalues, and misregistered data, these occurred in Cameroon, Ethiopia, Nigeria, South The digital data recorded on tape are configured Africa, and Zaire. These areas were exduded from the into pixels by tlhe image-processing system. An ab- final classified images because they would produce sence of data in a pixel can occur because of sensor, classes that were impossible to interpret transmission, or processing errors. Unless attended to Consequently, we produced a cloud mask which before processing, these errors remain in the processed- was overlaid onallof thefinalimages. Weconstructed

10 Mappinga/LandCoverClans It1 the mask by extracting information on cloud occur- Differenceimages were created by subtractingone rence pixel-by-pixelfor each month and then sum- set of monthly NoVI data from another and adding a ming the monthly data. lhe mask shows the pixels constant. The constant was added pixel-by-pixelto where cloud restricted the calculationof the mmvifor correspondingpixels to ensure that all values were at least onemonth during 1986.Areasunder this cloud positiveand could be displayed. The months used to mask thus lack information on land cover, and these createthe differenceImages were chosenon the basis areas are not included in the calculations of area, of known phenologicalcharacteristics of Africanveg growing stock,and yield. The extent of cloud-affected etation and land use. pixels is summarized country-by-countryin table3-1, and thedistributionof cloudcoverismappedin figure Table 3-1. Cloud Cover in 1956Imagery 3-1. Data for one of the 10-day periods in March were - o -o. -j-Arcn Area misregisteredwith the other images,offset to the east by six pixels.To solve this problem, we simply rereg- WestAfrican Sake! istered these data to the other 10-day-perioddata. The BurkinaFaso 0 0 March NDviimage then was recalculated and these - h-Chad 0 0 data were used in the Phase III analysis. TheGambia 0 0 Mauritania 0 0 Phase II-Initial Image Interpretation Niger 0 0 Senegal 0 0 In this phase, we derived images from the data and WestAfrican Cost identified and mapped provisional.land cover Benin 0 0 classes. C6ted'lvoire 0 0 Ghana 0 0 -Imagery Denrvedfrom AVHRRData Guinea 0 0 Guinea-Bissau 0 0 Variousimageproductswerederivedfromthemonthly Sberia -o11,362 1- NDviimagery during this initial interpretation phase Siea Leone 263 O n which provisional biomass classes were identified and mapped. The images used in this phase were: - Centr Africa Cameroon 14,649 3 . Individualmonthly images -wvrCentral African Republic 0 0 Individual monthly NDv images .Cog- Congo 0 0 * Mean annual NVI images EquatorialGuinea 1,634 7 e Differenceimages between two monthlyNDVI values Gabon - o * Unsupervised classification images. Zaire 66,818 3 SouthemAfrica All of the images were produced at various scales, Angola 1,634 0 ranging from the entire continent to individual coun- Botswana -0- 0 tries,tofacilitaternterpretationandimapping.Individ- Lesotho 211- 1 uacin images were prepared foreach month.Because Malawi 896 1 Mozambique 5,744 1 the data were supplied directlyfrom NASA/GSFC,image Namibia 1,475 a production required only tape unloading, inspection south Africa 2,37 0 for errors, and color coding of the image using the Swaziland 0 0 standard NAsA color scale (seethe section in Chapter 2 Zambia 2,002 0 titled "VegetationandLandCoverMappingfrom NDVi Zimbabwe a 0 Data"). ~~~~~~~~~~~~~Hornof Afiica A mean annual Gvi image was created through Djibouti 0 0 pixel-by-pixelsumming of all monthly Gvivalues for Ethiopia 15,071 1 corresponding pixels. The sum of the GVIvalues for Somalia 0 0 each pixel then was divided by 12 (months). This Sudan a 0 mean-annual image provided a good indication of EnstAfrica annual vegetation productivity and the spatial varia- Burundi 1,686 6 tion within it. It is analogous to the integrated NDVI- Kenya 4,216 1 images produced by other workers (see Chapter 2), Rwanda 4,058 2 but differs because this image is calculatedfrom the Tanzania 7,325 1 area under the annual NDvicurve. Uganda 3,636 1 12 EstimatingWoody Biomass in Sub-SalwranAfrica

Figure 3-1 Distribution of Cloud Cover in 1986 Imagery

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Two types of difference images are particularly use- or the onset of winter conditions (such as cooler tern- - ~~fulin thleinterpretation of land cover classes: - peratue or tSheincesd frequency of frosts). -- 1.Images in which data-for the low-w period 2. Imagesin which dataforthehigh period are -(vegetationsenescence) are subtractedfom data for subtracted from dab for the low-wvi period on a the high-wow period(maxiumu greenness)on apixel- pixel-by-pixel basis. These images provide informa- by-pixel basis. Such images provide a good indication lion on the greening of vegetation. - of vegetation dieback in response to declining sea- In this phase of the analysis, classification of images sonalrainfall,varyinglevelsofresidualsoilmoisture, was restricted to unsupervised classification. In this Mappingof Land Cover Class 13 context, unsupervised classificationis the clustering of Southern African Development Community (sAwc)re- pixels into statistical groups, defined by the temporal gion (Millington and others 1989).Second, the United distribution of their NDVIvalues. Four months were Nations Educational, Scientific, and Cultural Organi- chosen for the unsupervised classification. These rep- resented periods of high NDvland low NDvi and the two intermediate periods during which the NDvI values Figure 3-2. NDVIProfiles, Summary Land Cover were increasing or decreasing at varying rates, de- Classes 0,1, 2 pending on the type of vegetation and land use. These DESIC data then were clustered such that pixels having a (SummayClass 0) statistically similar range of values over the 4 months 0.6 were grouped into the same zlass. o.s -Nonhser MaurirAnin In addition to the images just described, temporal EasternNanibia profiles of the NDVI values were plotted; these are 0.4- called NDviphenologies. These profiles indicate the seasonal fluctuations of the ovi,which can be used to z 0.3- analyze and interpretseasonalvariations inphotosyn- 02 thesis, leaf area index, and biomass production. Each point represents the average NDviover the same 3 x 3 D.1- pixel square area on each monthly image. Represer.ta- tive temporal profiles are provided in figures 3-2,3-3, O- I J and 3-4. Althoughtheyrelate tosome of the land cover n F Mar Apr May Jun Jul Aug Sep Ot Nov Dc classes mapped inPhase m, they also are typical of the profiles derived in Phase IT and were used in the provisional identification of land cover class and in field verificatiorn GRASSLAND

Iden tfication and Mapping of Prouisional i (SumLaar (ass 1)

CoverClasses - CentralNiger South Africa/ \ All of the images were evaluated on-screen, and hard 0.4/ copy imagery was generated. The hard copy images - were used to identify and map land cover dasses on a 03- 1:5,000,OO-scalebase maps for the six areas where _ field checking was undertaken (a) South Africa and Swaziland, (b) western Zaire and Ccngo, (c) West D.1- Africa-Senegal and the Gambia, (d) West Africa- Mhali (e) West Africa-Cbte d'lvoire and Ghana, and o- ' , - M .n A p O N.c. (f) Ethiopia.JaFeISf)- Ethiopia : ~~~~~~~~~~~JanFeb Mar Apr May Jlm Jul Aug Sep Oct Noy Dec Identification of vegetation tpes in these areas em- ployed the criteria of.

* Vegetation phenology, obtained from temporal profiles of the NDvivalues and the seasonality (dif- WOODEDGRASSLAND ference) images - Class 2) * Spatialpattemsofvegetationonmonthlyandmean Cenan]Sudan annual GVIimages 0.5 Namibia * Secondary data sources, particularly vegetation, land use, and forestry maps, but abo includmg environmental information such as geological, soil, > and topographic maps and statistics on climate. Z D0-. We decided to undertake the initial mapping of provisional land cover classes at the scale of 0D-1

1:5,000,000 for two reasons. First, this scale had been o I _ used successfully for woody biomass mapping in the Jan Feb Mar Apr May Jun Jul Aug Sep Oc Nov Dce

7.~ ~ ~ ~ ~ ~ ~ - . 14 EstimalingWoody io mass in Sub-SalaranAfrica

Figure 3-3. NDVIProfiles, Summary Land Cover Figure 3-4. NDVIProfiles, Summaiy Land Cover Classes 3, 4,5 Classes, 6,7,8 SHRUBLAND WOODLAND (SummaryClass 3) mmaryClass 63 0.6 ~~~~~~~~~~~~~~~~~0.6(umr Cas6

- CapcProvince South Afric 035 0.5-

0.4- 0.4-

0.3- n 0.3 z ~~~~~~~~~z 03 02 - SouthernBurkdna Fao 0.1 0.1- - NorthwestemZambia 0 .1 1 1 I I - I -I I °- i * - I I I I I Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dcc Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

BUSHLANDAND THICKET HIGH WOODYBIOMASS MOSAICS (SummaryClass 4) (SummNryClass 7) 0.6 0.6- _ CenWalMali 05--Sox lomaia 0.5

0O4 OA-

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LOWWOODY BIOMASS MOSAICS FOREST 0.6 (Summary Class 5) (Summary Class 8) NorthemBotswana 0.5- 0.5

0.4- 0.4-

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0.1-* - : - .. 0.1- - SouthcrnCamcroon 0.1. - - _n -Nonheastem Zahi

0- p, £ I* I I I I I0 O m l i II 1 1 ,d Jan Feb MnrApr May Jun Jul Aug Sep Oct Nov Dec Jan Feb MarApr May Juan Jul Aug Sep Oct Nov Dec zation (uNBsoO)VegetationMap of Africa (White 1983) pretations This map was compiled from previous was produced at this scale. floristic maps, as well as expert review, but is not a The uNsscomap is one of the most recent vegetation land cover map. Nevertheless, we adopted the broad maps covering all of Africa and provides the most mapping units devised by White (figure 3-2). Adoam consistent reference source for checking image inter- tianrwas possible because the classes of land cover are Mappingof LandCover Class -15 related to different vegetation communities (forexam- The final classification was based on the 6 months ple, forest, woodland, shrubland, bushland, grass- of January, April, June, July, October, and Decem- land, and desert) or types of land use. Consequently, ber. These months were chosen by a process of elim- their distribution does not exactly correspond to any inating the other 6 months of the year. August was one previous botanical or ecological study of the re- eliminated because it had high-altitude cloud cover gion, although they are broadly comparable to most north of the equator. The months of February, regional vegetation maps. The structure adopted is March, May, September, and November were elim- discussed in Phase l. inated because correlation coefficients >0.9 were discovered for the adjacent-month pairs of January- Phase 111-Automatic (Supervised) February, April-May, May-June, September-Octo- Classification and Mapping of Land Cover ber, and October-November, creating a virtual data Classes redundancy. A by-product of this decision was that central processing unit (cpu) time for the classifica- The final biomass class maps were produced using tion using only 6 months of data was reduced dra- supervisedclassification.Supervisedclassificationisa matically compared with that using 12 months of partcularly powerful image-processingprocedure be- data. cause the value of each pixel in each spectral channel Previous work on land cover mapping has shown is compared with various sets of pixel values (called that using more months in the analysis inproves the training statistics) established from preselected, classification accuracy when compared with training known areas (called traimnig sites). The individual site statistics (Townshend, Justice, and Kalb 1987). pixels are assigned to the most suitable class,based on Althoughwe donot question this finding, the decision the training site statistics. In this study, the data used to use 6 months of data was based on operational for supervised classification were not from different critera rather than scientific.It should not be assumed spectral changes but were Gcnfrom different months. that accuracy necessarily would increase if more As a consequence, the classification identified and months in 1986 were used in the classification, but mapped pixels having similar NDVIphenologies. Dif- accuracy would increase significantly if data from ferent algorithms canbeusedinsupervised classifica- other years were included. The reason is that the NDw tion, but in this project a maximum likelihood classi- is very sensitive to rainfall and soil moisture condi- fier was used. tions, which vary considerably from. year to year Training sites were identified from Phase II inter- across much of Africa. pretations. These were located in areas where provi- The most accurate map of land cover that could be sionally interpreted land cover classes attained nmaxi- produced would use a data set back to 1981,when the mum areal extent, or where they were known to be NDvidata first became available. We strongly recom- distinctive. Training sites were selected from field mend that future use of the NDvidata for application teamreportsandpreviousresearch.Trainigstatistics of natural resources employ long-term data sets, were generated for all the types of land cover identi- rather than data sets for single years. fied, and the data were classified on this basis. This produced an automated classification of sixty land Land Cover Mapping cover classes for all of Sub-Saharan Africa. We decided to use data spanning 6 months for the The land cover classes were reinterpreted using the supervised classification. This decision was based on same citeria employed to identify themin Phase IL At two criteria. First, in the woody biomass assessment this stage, classes having strong similarities were carried out for the SAncregion using the NDvidata, the merged, producing forty-three land cover classes. main technique for map production was supervised These are listed in table 3-2 and shown on the four classification(Milhington and others 1989).Evaluation regional maps at the end of this volume. The classes of the imagery showed that a supervised lassification were reviewed by experts in the workshops held in of land cover classes based on the monthly GVIdata Abidjan and Nairobi, and recommendations were was more meaningful than other techniques. made for further merging of classes. Secnd, significant temporal autocorrelation exists Most of these mergers are of dasses having statisti- in the NDvidata for adjacent months, which could lead cally similar Nv curves which, on the basis of floristic to data redundancy if all 12 months were used in the and ecological criteria, were incorrectly split in the classification. We tried classifying separately two se- Phase Ill analysis.The special case ofcultivation mosa- quences of data for alternate months-January to No- ics in West Africa and Ethiopia, however, presented a vemberandFebruarytoDecember-andfortheentire more difficult problem. In the West African coastal 12 months of data. The visual differences among the zone, areas originally classified as different types of three classified-image maps were insignificant. humidtropicalforestandforestregrowthweremerged 16 EstimatingWoody Biomass in Sib-SalwranAfric -

Table 3-2. Land Cover Classes for Sub-Saharan into two classes: High-Productivity West African Cul- Africa tivation and Forest Mosaic and Medium-Productivity Classnennber Land courrclass West African Cultivation and Forest Mosaic. This merger was based on the realization that very 0 Desert little humid tropical forest remains in this region. The I Grssland remaining forest is in small blocks and reserves inter- 11 Vyddrno Grassland spersed with rubber, cocoa, and coffee plantations, 13 EtHidropinmorphicGraslaneS farms, and a seral succession forest regrowth. This 13 - Etiopian MontaneStep,oe 14 MontaneGrassland and Heathland patten of land use occurs at scales that cannot be 14 - - : - mapped with any accuracy from the condata. 2 WoodedGrassland In the highlands of Ethiopia, a similar problem exists with small land parcels having different bio- 22:21 AcaciaSemcideseWoodied Wooded Grassland Grassland 23 PlateauWooded Grassland mass levels and NDVI profiles. Here altitude is art 24 TransitionalWooded Grassland additional factor, so we introduced altitude into the 25 EdaphicWooded Grassland mapping procedure. The 2,000-meter and 3,500- 3 Shnabland meter elevation contours were digitized and a 31 VeldShrubland and Cultivation laid on the classified image. Except for Moncane 32 HllShrubland Forest, all classes occurring between 2,000 and 3,499 33 BushyShrubland meters in the area weremerged to form a class caled 34 KalahariShrubland Woodeld hbland Highland Cultivation Mosaic. Ihose above 3,500 -35 meters were merged to form a class called Ethiopian 4 Bushknd and Tl-cket Montane Steppe. 41 -Dry Axia-CommiphoraBushland 41 DryA TbicketCOIZ-and Calasses of land cover are defined as areas having 42 - FynbosdThicket types of vegetation or land use that are comparable in 43 MoistAcacia-Comm47honzBushland overall biomass, productivity, and seasonality. They and Thicket may, however, combine more than one type of ecolog- 44 Sahel-SudanianAcacaWooded ical structure (for example, forests and woodlands) 45 -EsarpmentWoodedThicdet and many floristic units. In this respect they differ 4- EscarpmentWooded Thicket significantlyinplacesfromtheuNuScVegetation Map 5 LowWoodyBiomss Mosaic of Africa (White 1983). For the purposes of wood 51 AcuegaWoodland Mosaic 5-2 EastAfricanLow Woody Biomass energy planning however, a classification based on osAic parameters that have been correlated with gowing 6Woodland-stock and productivity elsewhere is of more use than 61 OpenWoodland a floristic-ecologicalmap. 62 DrySudanian Woodland The maps of land cover classes are one of the final 63 Sudan-EthiopianWoodland and Thicket products of this projectLThe maps include: 64 SudanianWoodland 65 MoistSudanianWoodland * Four regional maps depicting land cover classes, 66 SeasonalMdiowboWoodland f - appearing at the end of this volume. 67 Wet hMomboWoodland A regional summary map of land cover classes, 7 HighWoody Biomass Mosaic constructed by categorizing the land cover classes 71 Evergreen Woodland Mosaic 72 Cultivation and Forest/Woodland Mosaic into eight groups on the basis of the dominant 73 Cultivation and Forest Regrowth Mosaic ecological structures (figure 3-5). These groups are 74 GuineanWoodland defined by White (1983). 75 High-Productivity WestAfrican Maps of growing stock and sustainable yield, ap- Cultivation and Forest Mosaic peaning in Chapter 7, figures 7-1 and 7-2. - 76 Medium-ProductivityWestAfrican Culvation and ForestMosaicInterpreting AVR vi Data for Woody 77 HighlandCultivation Mosaic 8 Forest Biomass, Stock, and Sustainable Yield 81 Martgrove 82 Ever Forest As has been shown, we identified classes of land cover 83 Coastaland GalleryForest by using imagery derived from the AVHRR data to- 84 MontaneForest gether with secondary ecological, environmental, and 85 MesophilousHumidTropical Forest forestry dataL The principal characteristics used to 86 HumidTropical Swamp Forest distinguishthe classeswere (a) differencesin vegeta- 87 OmbrophilousHumaid Tropical Forest tion cover,as indcated by their monthlyNr values; Mappingof LandCover Class 17

Figue 3-5. Regional Summary Land Cover Classes

. 3? 9~ 1).

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Landckss.2cover I -

asslrand d -Wdtan n rt to pm p f reaiob e te - a lioncatedbyareviewland thev ~nuassof : -termnthly: o wrvaus(8 an th auhre shwta lsiiaiosfo nlsso

.- Low woodybiomass moacs.

Thbai: = Woodllandaruet-Il - fo inepetto of th veeato tye of Afia In sumay the. reasons^'. G --. Highwoodybiomassmosaics . 0 0 x,,ff<_- -V- - t~~~~~~~~

(b) dife nlemanua primamyprocduction, as indi- Townshed, Jushce, and Kalb (1987). In d-ee works, catedby the annualsums of their monthly NDvivalues; the authiorsshow that dassifications from analysis of and (c) differeces in phenology, as indicated by their data from satellite rernote sensin g correspond closely temporal profiles of NDVL -. to vegetatio,nmaps and field observations of prndcpal ThebasicargumentsforinterpretationoftheAvnn-. vegetatior, types of Africa. In sunuay, the reasons derived NmV data in relation to primary produc- .for this are (a) the strong relatioribetween the and tion are reviewed by Tukr and- others (1985 andl LeafArea Index (Lm) and (b) the regular acquisition of 18 EstimatingWoody Biomass in Sub-SoliaranAfrica cloud-free imagery using the AVHRR,which enables the imagery have been related to rainfall patterns in the phenology of the vegetation to be observed across the Sahel (Malo and Nicholson 1990). entire continent. 'A very strong seasonality in the vegetation also The most important factor that determines the type exists, caused by the distinct dry and rainy seasons and productivity of vegetation across most of Sub- (Samiento and Monasterio 1983; Rutherford 1978). Saharan Africa is rainfalL However, in the far south The seasonalty of rainfaUlaffects the vegetation di- and at high altitude, temperature fluctuations are also recly by affecting primary production (Woodward important (for example, in East Africa and the Ethiop- 1987) and indirectly by the prevalence of fires in ian Highlands). Strong correlations between rainfall the dry season. The latter has selected species that and vegetation often have been observed in Africa in have various forms of dormancy (Sarmiento and relation to vegetation community, composition, and Monasterio 1983).The phenology of African vegeta- production-in southern Africa by Lamotte and tion is easily detected by the Nay!calculated from the Bourliere (1978) and Rutherford (1978),in Zaire by AvmRRdata, and this contributes significantly to the Malaisse (1978), and in West Africa by Menaut and information content of the multitemporal classifica- Casar (1979, 1982). Such patterns depicted by NDWi tions used in this project (Tucker and others 1985). -~~~

Woody BiomassAssessment

In this chapter we review problems. in the data base, quently, the quality of the data base is extremely vari- the procedure for area calculation, and our method of able. Ideally, data for each land cover class in each interfacing data to produce the maps of growing stock country should be used, but such data either do not and sustainable yield. exist or are not accessible.Even at the regional level, these data frequently are unavailable. Beforewe could Data Base for Biomass Estimation interpret imagery, we were forced to derive estimates forsomeclasses andcountriesfhroughgeeralization, We define growing stock as air-dried, above-ground extrapolation, or interpolation. Woody biomass, in tonnes per hectare. Sustainable Also,.many of the data collected are not accompa- yield we define as the mean annual increment of air- niedby sufficient methodological detail to permit sat- dried, above-ground woody growth, also in tonnes isfactoryevaluation.Intheabsenceofotherdata,hoow- per hectare.per year. ever, these estimates had to be used. Where no data were found, estimates were based on values in the Problems in the Data Base existing literature, bearing in mind empirical data from similar land cover classes and geographical Numerous problems exist in the data base and we areas. review these diffculties in this section. In summary, Our main sources ofLiterature were the PAoForestry the problems include: Departmentlibrary inRome; Department of Forestry Library at Edinburge University; The World Bank - Extremely variable data from secondary sources LibraryandreferencedatafileinWashington;thesADc v Insufficient methodological detail data file held at the Department of Geography, Uni- * Merchantabletiberstudiesexcludefuelwoodand versity of Reading; and the Biomass User Network at understory King's College, University of London. Much of the * Studies of selected species and classes may be material at the first two sources concerns forestry pro- unrepresentative . jects, both local and countrywide, and consists of for- Studies assess volume, not mass est inventories or otherestinmtes of commercial wood, * Incompatible terms and no classificationcrteria often to the exdusion of fuelwood and omitting esti- * inconsistent or missing data for classes and regions mates of natural and seminatural vegetation. Further, * UnrepresentatiLvedata from limited sampling and these estimates usually are of woody biomass of mer- no seral information chantable size, such as timber with a diameter greater * Studies do not relate biomass and population than 10 centimeters, or in many cases 30 centimeters. distributions This clearly omits much wood of great significance * Studies do not identify nonfuel uses of selected with regard to fuelwood. speciesr In particular, most studies exclude the understory, * Extensive nonforest vegetation near culture is a resource of great significance in fuelwood supply. excluded. Brown and Lugo (1984)suggest that the total biomass for the understory in closed forests is less than 2 per- The data base used for estimating growing stock cent, whereas in open forest the percentage may be and sustainable yield for each land cover class was much higher. They further point to large underesti- derived from a number of secondary sources. Conse- mates that are likely to occur if only stem wood is

19

''- '';~~~ ' 0 '~/' '' ' -- - ; 20 EstimatingWoody Biomass in Sub-SahrmnAfrica considered. They suggest that the ratio of total woody extensive literature search, data of good quality are biomass to stem wood biomass in closed forest may be lacking for particular land cover classes, such as 1.6andasgreatas2.9 inopenforest,withthe increased high forests and the woody biomass mosaics, and proportion in the lower stories. Clearly, where mer- for some critical regions, such as the Sahel and East chantable timber and stem wood biomass are the Africa. focus, and the understory and standing dead wood are Yet another problem is whether the data are repre- ignored, a significant underestimate of the woody sentative. Factors such as the successional state of a biomass resource is likely. system can substantially affect growth rates of vegeta- These problems are generaUy recognized, as is the tion, but most studies give no indication of seral stage. fact that the studies are concerned with a limited num- Many studies also rely on very small sampling areas, ber of land cover classes and tree species-those capa- creating the possibility of a large sampling error be- bleofproducingcommercial-yields,andwhicharenot cause the data do not represent land cover classes necessarily representative of an area. mapped on a continental scale. Also, these estimates generally are concerned with No attempt was made in the present study to relate the volume of wood rather than its mass, and this is the distribution of woody biomass supplies to popu- particularly true for estimates in francophone Africa. lation distribution. (We do note that many of the stud- In these cases, conversion to air-dried mass within tlhe ies have been in areas far from population centers, data base was necessary. This contrasts with the situ- possibly malkng them inaccessible as woodfuel re- ation noted for the southern African states (Millington sources.) This shortcoming can be addressed by addi- and others 1989), in which the commonest data avail- tion of current population estimates at the provincial able are estmates of the mass of dry materiaL Al- or district level to existing biomass data in a geo - though oven-dried biomass is preferred for energy graphic information system (aS). studies, so few make reference to it that air-dried There also has been no attempt to distinguish tree biomass is used here. species -that are used locally for specific purposes, Adjustment from volume to mass in the data base which would exclude them from use as fuelwood. used the following conversion factors: This problem needs local research and more data on

______-the quantit of individual species present. At this time Woodtype Aerage air-drieddenity little detailed information is available for the data Acac-Conznmphorawoodland 0.6tonnes/Mr3 base. Mliombowoodland it was not possible to take account of the extensive (Brnchystiq&-Julbewanrdia) 0.9 nonforest rees and shrubs that occur in dose associa- Rain forest 0.65 tion with villages and farmland in many areas. The SouthAfiicanwoodland 0.6 spatial resolution of the images was inadequate for their assessment, and conseq7uentlyalmost no mean- These coefficients were derived from the literature ingful data exist on the growing stock and growth and discussion of the problem within amr. In a few rates of surh vegettionL Neverthieless, these trees and studies, stacked volume of wood (stans) is indicated, shrubs may form an important source of woodfuel for for which we used the conversion of 0.25 tonnes per manyruralpeoplewhosustainablycollectwoodyand stat. Volume-to-biomass conversions for commercial nonwoody biomass near their homes (Leach and timber species in high forests do not necessarily rep- Mearns 1988;Munslow and others 1989). resent the mensuration statistics forwoodfuelbecause The combined effect of these factors produces a variations occur due to species differences and their high degree of variability and unreliability in the use. For many species having less-dense wood, no data for each country and each land cover class. The data were available at all. final tabulated data must be regarded with these A further difficulty was the incompatibility of de- limitations. sciptive terms used for vegetation types and the lack of clear definitions and criteria for their lassification. Limitations of Datafrom Literature Sources In some instances this made problematical the assign-- ment of data to a particular land cover class. Table 4-1 indicates the growing stoDkand sustainable Inconsistent data recording is another problem in yields deriveedfrom the data base. The median value creating a standardized data base. Such incorsisten- reported for each class represents the central value of ciesreflectthepartcularinterestsandobjectvesofthe a range of estimates from the literature perfinent to forester or researcher with the result that many refer- that class. Where no estimates were available, values ences provide estimates of, for example, growing of growmg stock and sustainable yield were denved stockbutnotofgrowthrates,orviceversa.Despitean from ecologically similar classes. Few estimates are WoodyBiomass Assessment 21

Table 4-1. Growing Stock and Sustainable Yield Data, 1953-90 Crowingstockair- Sustinableyieldair- Leandcoer cdss dry t hi' range Median dry thayf'range Median Sourc! 1 Grassland 11 0.63-3.90 (2-27) - [0.101 Huntley 1978 12 - [2.27r - [01 n. 13 - [2.27' - [ p na.. 14 - - 1oaj n227Ja.a,. 2 WoodedGrassland 21 1.80-4.80 (3.3) 0.04015 (0.10) Openshaw 1982;Andeke Lengi 1987 _[33F - [0.101 n.a. 23 1[33f _ [0.10]6 n.a. 24 0.23-1.00 (0.62) - [0.10 Rutherford 1978 25 - [33f - [0 n.a. 3 Shrubland 31 6.10-11.00 (855) _ i50o. Huntley 1978;Rutherford 1978 32 4.50 4.50 . [0.50]e Rutherford 1978 33 5.00-15.00 (10.00) - 050g. Rutherford 1978 34 -- - - - o _50a.so na. 35 3.70-7.50 (5.60) - - [0.50 Rutherford 1978 4 Bushiandand Thticket 41 7.80-20.00 (13.9) - [021]' Huntley 1978 42 2.00-35.01 (1851) - [0.21]' Rutherford 1978;van Wilgen, Higgins,and Bellstedt1990 43 3.03-30.80 (16.92) 0.04-0-38 (0.21) Rutherford 1978 44 0.46-235 (1.41) 0.35 0.35 Daus, Guero, and Ada 1986; Andeke Lengui 1987 45 - [18.51] - [0.21]6 nma. 5 Low WoodyBiomass MOsait-c 51 -223 22.30 - Rutherford 1978 52 9.44-3355 21.50 024-1.M 0.63 Stomgaard 1985; rrc(u) 1987; Perssn 1975 6 Woodland 61 0.92-56.87 (29.40) 0.02-0.85 (0.44) FAo/PNuD1978; Biandhi1986; Andeke Lerngu 1987 62 9.00-44.40 (26.70) 0.16-138 (0.77) 1Ao1984;FAo/PNTD 1978; C16ment1982 63 [26.70]' - 10.44]' na. 1 64 [26.70]' 0.15-0.77 (0.46) Biandtii986;aement1982 65 - [26.701' 0.45-0.51 (0.48) Cl4ment 1982 66 Z25-109.00 (55-63) 0.45-1.32 (0.89) Persson 1975;Jadckson 1971; ETc(uJ4 1987;Guerreira 1966; Chidumayo 1987 67 16.00-222.00 (119.0) 0.41-2.25 (133) Guy 1970,1981; Stomgaard- 1985; Lundgren 1975; ETCQUK) 1989;Persson 1975;Kennard andWalker1973;Guerreiro 1966 7 High WoodyBwiass Mosaic 71 2.8-738 (5.13) - [0o191 Malleaux 1980 72 . - 60- [019] a. 73 16.84 16.84 - 0.19 Bianchi1986 74 -1 6 .8 4 [011 na.[k 75 . - [16.84]- - [0.19]1 ta. 76. -. [684] - [019' iLa. 77 - [16.84)k - [0.19)' na.

(Tablecontinueson thefolltoiing page) 22 EstimatingWoody Bioniass itn Sub-Salarmn Africa

Table 4-1 (continu-ed) Growingstockair-- Sustainableyieldair- Land coverclass d ry li" ruange Median dry tI4 ye ' ran Medianu Soterc 8 Forest 81 246.80 246.80 29.49 29A9 Christiansen 1978;Golley and others 1971 82 60.00 60.00 - [4.98]" Baines1980 83 88.78 88.78 4.98 4.98 Christiansen1978 84 99.00 99.00 1.73-6.21 3.97 Chapmanand White1970; nrc (U.K) 1987 85 22.75-232.80 (127.78) 0263-0.65 [14.8r Pecha1986; FAO/IfUD 1978; Marsch1978; Bianchi 1986; Greenlandand Kowal1960; Nye 1961;John 1973 86 - [127.78]m - [14.80r 87 69.78-140.00 (104.89) 1450-15.10 (14.80) Rdpubliquedu Togo1987; Bartholomew,Meyer, and Landelot1953

- Not available. n.a.Not applicable. o Medianvalue. [I Valueto use in calculationswhere no data exisL a. Derivedfrom values for Class 11; b. Derivedfrom values for Cass 21; c. Derivedfrom values for Class 21; d. Derivedfrom values for Class33; e. Derivedfrom data givenfor differencesand stands of 33/34 ibsasheath) in Rutherford(1978) and translatedto Classes31, 32, 34, and 35; f. Derivedfrom values for Class42; 8; Derivedfrom values for Class43; h. Derivedfrorm values for Class52; i. Derivedfrom valuesfor Class62 j. Derivedfrom values for Class61; k. Derivedfrom values for Class73; 1.Derived from valuesforClass 73; n. Derived fromvalues for Class85; rLDerived from values for Class83; o. Derivedfom valuesfor Class87. available in the summary classes of Grassland (1), Furthermore, only two of the BushLad and Thicket Wooded Grassland (2), Low Woody Biomass Mosaic classes had any data on sustainable yield- (5), and High Woody Biomass Mosaic (7).-The estimates for the Forest classes are usable in the The values for all Grassland classes (11-14) are data base, although four of the seven classes had only based on a sample of estimates for growing stock for one value for growing stock or sustainable yield. Of Veld Grassland (11). The several studies quoted by particular importance are the estimates for Mangrove Rutherford (1978)on grasslands in southern Africa are forests (81), which are very small because they came mainly concerned with herbaceous biomass. No val- from ecologically constrained areas such as Somalia ues for sustainable yield were found for these classes and Guinea-Bissau. These low values dearly do not and therefore values have been inferred from data represent the bulkof mangrove forests in Africa, so we gathered for wooded grassland systems. In practice, decided to use the value of 246.8 tonnes per hectare given the lesserbiomass present in the grasslands, the with an equivalent sustainable yield value of 29.49 sustainable yield would probably be lower than that tonnes per hectare per year. These values come from forw6odedgrasslands.Asimilarlackofdataexistsfor estimates of mangrove stocks and productivity in these wooded grassland systems, however, and be- Puerto Rico (Golley and others 1969) and Thailand cause these classes have low woody biomass compo- (Christiansen 1978). nents, they are likely to become areas of critical wood Few quantitative data were available on the woody supply if demand should increase. biomass stocks and yields for the Low and High For Shrubland classes (31-35), Bushland and Woody Biomass Mosaics (5,7). Of the two, more data Thicket (41-45), and Woodland (61-67), the levels of exist for Low Woody Biomass Mosaics, mainly be- data available are generally better. Nevertheless, data cause -hey are most widespread in southern Africa on growing stock are notably absent for some import- where significantly more ecological studies have been ant woodland classes (63-65) in East Africa and the conducted and estimates have been made of woody SaheL In addition, far fewer data are available on biomass for planning fuelwood energy. Unfortu- sustainable yield for Shrubland and for Bushland and nately, the same cannot be said of the High Woody Thicket classes than are available for the equivalent Biomass Mosaics anywhere in Africa. growing stocks. Only one value of sustainable yield We recognize that the ratio between growing stock for Shrubland was obtained from the literature, and and sustainable yield shows a level of inconsistency that had to be estimated from studies of stands of that can be attributed to the use of median (central) varying age of bumedfynbos heath (Rutherford 1978)- figures from different studies. WoodyBiomass Assement 23-

Area Calculations of Land Cover Class cover class or woody biomass and consequently are omitted from the tables. A map of nationalboundaries for Sub-Saharan Africa 2. Some countries had significant cloud that af- was digitized and warped to the land cover class map fected the classificationof land cover (table 3-1).These derived from the supervised classification of AVEIR areas were masked from the final imagery (Chapter 3) imagery. In addition, the outlines of the main lakes and are not recorded in the tables. and reservoirs in Sub-Saharan Africa were digitized 3. Supervised classification establishes a cass of and warped to the cG imagery. This enabled the maps pixels which were rejected because they were outside of the land cover classes and summary classes (see the statistical limits of the land cover classes. These Chapter 3) to be overlaid with national boundaries, pixels were not assigned to any land cover class and lakes, and reservoirs. constitute a further proportion of the area of each A program was written to count the pixels in each country that is not mapped or used in the woody land cover class within each country across the entire biomass database. image. This produced a table of pixel counts by land. cover class for all Sub-Saharan African countries. The Interfacng Area Growing Stock and Data table was imported to a spreadsheet and used to cal- on Sustainable Yield culate growing stocks and sstainable yields. The area of each country was calculated by sum- Data on biomass growing stock and sustainable yield, ming its pixels and multiplying them by the area of assigned to land cover classes, were transferred into each pixel. This was possible because the map projec- the spreadsheet directly from the data b-se. Macros tion used to display the Gn data, the Hammer-Aitoff were written within the spreadsheet to calculate the X projection, is an equal area projection, and therefore following information from the interfaced data base each pixel occupies the same area across the entire files: image. The areas thus calculated were compared to areas of each country taken fromstandardsources (for * Growing stock by biomnassclass and summary bio- example, Stonehouse 1985). In no instance were the mnassdass differences between pixel-derived areas and those * Sustainable yield by biomass class and summary given in.the literature greater than 1 percent of the biomass class. country area. These small differences are easily explained by the The growing stock and sustainable yield. for each raster nature of the international boundaries and land cover class were used to produce maps for all of coastlines from the overlays on the remotely sensed Sub-SaharanAfrica.Mappingwasachievedbyexam- imagery, which depict "smooth" curves and lines on ining the data on stock and yield (table 4-1) and iden- maps as steplike boundaries. Note, however, that the tifying natural breaks m both, which defined five summed areas of land cover classes for most countries classes of stock and yield. Eadh land cover class in the are less than the recorded area of the countries. These final supervised classificationimage was assigned to discrepancies arise for three reasons: a color-coded stock class and a yield class to produce 1. The area of lakes and reservoirs is included in the mapsof growingstock(figure 7-1)aid sustainable the total country areas, but these have no data for land yield (figure 7-2). 5~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Descriptionof BiomassClasses

On a continental scale, the vegetation of Sub-Saharan In southem .Africa, tie Namib Desert stretches Africa forms fairly distinct bands that span the conti- along the west coast from southern Angola through nent latitudinally, although this zonation disinte- Namibia and into South Africa. The other significant grates in the extensive highlands associated with the desert areas are. parts of the Kalahari Desert in Bo- Rift Valley of East Africa, especially in Ethiopia. The tswana. In total, the Desert class covers nearly 4.1 map of growing stock (figure 7-1) shows a similar million square kilometers in Sub-Shran Africa. De- * pattern, with the greatest density of woody biomass. spite the dwarf shrubland on the fringes of the Namib centered on the Guineo-Congolian rain forest belt, Desert andafewwidelyscattered treesintheKalahari which extends through much of coastal West Africa Desert of southwestern Botswana, the overall contri- and across northem Zaire as far as Uganda. To the bution of Africa's desert areas to growing stock is south, biomass stocks decrease steadily from the ex- negligible. tensivemiombowoodlandsbetweenabout5%SandlS0 S 11 Veld Grassland covers only small areas over to the open woodlands, shrublands, and eventually much of Africa, but it is extensive in southern Africa, the veld grasslands and deserts of southem Afica coverng nearly 6 percent. The largest expanse covers North of the rain forest belt, a similar decrease in most of Lesotho and much of the Orange Free State growing stock occurs through rather narrower zones and southern Cape Province. Outliers are found of Guinean and Sudanian woodland, dry Acaci- throughout northwestern Botswana and around the Comnm4kmbushand and thicket, and the semidesert northeastern border of Angola. Woody biomass is wooded grassland, which eventually merges into the largely restncted to riparian woodlands and to small, Sahara Desert at about 200 N. East of the Rift high- widelyspacedtreesintheKalaiarithomveldofnorth- lands,muchofKenyaandtheHomarecoveredbydry western Botswana. The total contribution of Veld bushland and semidesert vegetation, giving way to Grassland to growing stock in Africa is negligible. desertincoastalEthiopia, Djibouti,andpartsof north- 21 Semidesert Wooded Grassland is most exten-. em Somalia, and to a lesser extent in northern Kenya. sive along the southern edge of the Sahara Desert, In total, Sub-Saharan Afica contains an estimated stretching eastward from southern Mauritania 65,689million tonnes of growing stock, producing a through the central areas of Mali, Niger, Chad, and sustainable yield estimated at 3,549 -milliontonnes a Sudan.ThesouthernmostareasareinnorthernKenya, year-. and the class is also important.in Somalia and the The following paragraphs summarize the growing eastern half of Ethiopia. The vegetation is grassland stock and sustainable yield for the most significant with bushes and small bushy trees (White 1983). The land cover classes listed in table 3-2. grassland is domninatedby annual species, and the 0 Desert dominates the northern portion of the cover is ephemeral except where shaded by larger study area, with the Sahara Desert. extending into trees. large areas of Sudan, Chad, Niger, Mal, and covering ThewoodycomponentislargelyofAcaciaspp.,with most of Mauritania. Desert also covers coastal regions a crown cover of less than 10 percent Woody biomass of the Horn as far south as northern Somalia Apart stocks are low-for example, Semidesert Wooded from a few woody species at the southem fringe of the Grassland covers more than 18 percent of the West Sahara,. most biomass is in the root systems of African Sahel region but provides less than 6 percent drought-resistant plants- of the region's growing stocl Population density is

.24 Dcriplioiof BlomansClasn 25 low, increasingtoward the south in the belt.ln Soma- tatioin,with scattered trees on the dune crests and lia, however,the semidesertarea supports more than shrubsrestricted to the troughs.In the hillsbordering 40 percent of th-epopulation, and their demand for the NamibDesert, tall succulentsand bushy trees up fuelwood has caused severe stress on the- trees to 5 meters are scattered in an open shrub layer of (Kamweti1984). Semidesert Wooded Grassland has a about 2 metersheight. (SeeClass 35, WoodedShrub- growing stock of nearly 364 million tonnes, with a land,for growingstock and sustainable yield statiscs.) sustainableyield of less than 14 million tonnes.The 35 Wooded Shrubland is similar to Kalahari severesocial consequences of depletingthis resource Shrubland(34). Although its distributionis similarto make sustainablemanagement vital. that of KalahariShrubland, it occursin slightlymoister 24 TransitionalWoodedGrassland coversll per- areas, oftenat hiigheraltitudes. Each of theseclasses cent of southern Africa,including 40 percent of Bo- has a growing stock of less than 150 million tonnes, tswana,20 percentof Namibia,and areasof northern althoughthe sustainableyield of more than 30 million and central South Africawhich add up to 14 percent tonnes for KalahariShnaubland compares to only 2.5 of that country.Overmuch of this area, the vegetation milliontonnes for WoodedShrubland. In such barren is similarto that of the VeldGrassland (11). In parts of surroundings,these classes represent a relativelypoor Botswanaand the OrangeFree State, this class consists sourceof fuelwood,and the presentrate of fuelwood of grasslanddominated by Aristida,with a numberof extractioneasily exceeds annual production. Karroidshrub comnmunitiesupto 5 metersin height.In 41 Dry Acacia-CommiphoraBushland and Thicket the Transvaal and southern Mozambique,this class occurs in the countries of East Africa and the Horn, includesZambezian woodland donmnated by Acacia extending over much of southeastern Ethiopia and in a mosaicwith veldgrassland. inland areas of southem Somaliaand eastem Kenya. Despite its large area, AtheTransitional Wooded Significantoutliers are found in central and north- Grasslandclass includes only 1.23 percent of the grow- westem Kenya, northem Tanzania, northeastern ingstockforsouthern Africa. Nonetheless, these areas Uganda,and the extremesoutheastem area of Sudan. are heavilycultivated and grazed.Because the major- The bushland is dense, often forming impenetrable itl of biomass is nonwoody,and accessis restricted thicketsattaining 5 meters in height, with scattered becauseof land tenure, TransitionalWooded Grass- emergenttrees up to 10 meters.With a growingstock land is a poor source of fuelwood.This class has an of nearly 944 million tonnes, this class produces a estimatedgrwing stockof nearly 146million tonnes, sustainableyield of only 10 million tonnes. Over- producing a sustainable yield of about 5.6 million populationand overgrazinghave severelydegraded tonnes. large areas of the bushland, often leading to 33 Bushy Shrubland occursmainly in East Africa desertificationaround boreholes. The considerable and southern Africa, covering 1.8 percent and 1.96 demand for fuelwoodexacerbates the problem. percent respectively. In Kenya, this class consists 43 Moist Acacia-Commiphora Bushland and mainlyof smallbushes and stunted trees, dominated Thicketis spreadin patchesacross southern and East by Acaia reficiensss. misera, although it also accounts Africain a roughlyarc-shaped distribution. The most for areas of montane vegetation in the eastern northerly,large area extendsdown the coastalstrip of AberdareMountains. In southem Africa,the largest East Africa from about 40 N in Somaliato the south areas are found along the west coast of CapeProvince coastof Kenya.A large triangulararea of moistbush- and on the northern fringe of the NamibDesert along land coversmuch of central Tanzaniaas far as Lake the coastof Angola.I-n Cape Province,the vegetation Malawi, and the arc continues through Malawi and is sderophyllousshrubland, with a few taller bushes parts of Mozambiqueand Zambia,eventually reach- but very few trees. In coastalAngola, this classcon- ing the coastof southernAngola Largeoutlying areas tains a rather open vegetation of small shrubs, with are found in the south of Mozambiqueand especially occasionaltAawa-Conmniphormshrub communities. in Swazilandand the Transvaal. Once again, grass forms a large proportion of the In East Africa,this classis principallydense bush- biomass,and wood production is low. From a total land up to 7 meters height, with grasscover growing growingstock estimated at 96.7million tonnes, Bushy to 1.5 meters.hi southernAfrica, however, this class Shrublandproducesasustainableyieldof lessthan 1.6 spans a wide range of floristicregions. The major nilliontonnes. Thus, the potentialforlarge-scale, sus- similaritybetween these areasis in theirsnsonal phe- tainable exploitation of fuelwood is extremelylimited. nology. Productivity peaks in the summer, sometime 34 Kalahari Shrubland covers4 percentof south- betweenDecember and May, depending on the area em Africa, including 10 percent of South Africa, 9 of Africaexamined. A declinesets in fromMay, with percent of Botswana,and 8 percent of Namibia. In the lowestproductivity occurring toward September, Botswana,Namibia, andnorthern CapePrrovince, this the end of the dry season. After this, production in- class consists argely of rather sparse sand dune vege- creases steadily.

'9 .. 26 EstimatingWoody Bioniass in Suib-SaharamAfrica

The moist bushland is rather more productive than 61 Open Woodland is scattered among the miombo the Dry Acacia-ComnmiphoraBushland andThicket(41), woodland of Tanzania, where its composition is sim- having a sustainable yield of nearly 77 million tonnes ilar to that of the surrounding vegetation, and in on 1,685million tonnes of growingstock. Nonetheless, Burundi, where the class is represented by moist Aca- the pronounced dry season ensures that productivity cia-Commiphora bushland and Acaia wooded sa- remains relatively low, limiting the potential for fuel- vanna. The vast majority of this class, however, lies in wood exploitation. the southem African region. Here it covers much of 44 Sahel-Sudanian Acacia Wooded Bushland southeastem Aingola and northevstern Namibia, forms a belt across North Africa centered on about northem Botswana, southweste, . smbia, much of 1? N, from Senegal in the west to central Sudan and Zimbabwe, and parts of southern Mozambique. This northern Ethiopia in the east. This belt lies between forms an irregular belt running latitudinally between Semidesert 1l ooded Grassland (21) to the north and the miombowoodland to the north and shrubland to Dry Sudanian Woodland (62) to the south. Sahel- the south. Open Woodland encompasses a variety of SudanianAcacia Wooded Bushland is generally found vegetation, including woodlands dominated by in areas receiving between 250 and 500 millimeters of Brachystegiaspp., Bakiaeaspp., and Burkeaafricana. rainfall a year. There is a herbaceous layer of mainly The growing stock is estimated at 743 million annual grasses, although perennial species are more tonnes, producing a sustainable yield of nearly 63 common toward the south of the zone. The ground million tonnes. Despite being an important source of layer is more persistent than that of semidesert, sur- fuelwood in South Africa and Lesotho, the low pro viving most of the dry season. The main woody spe- ductivity of this class makes hiigh rates of sustainable des are Acacia, increasing in height from 4 meters in exploitation impossible in most areas. the north to 8 meters in the south. 62 Dry Sudanian Woodland lies in a latitudinal The growing stock of nearly 4,203 million tonnes is belt immediately south of the Sahel-Sudanian Acacia the third largest of any class and produces a sustain- Wooded Bushland (44) previously described. From able yield exceeding 178 million tonnes. Processes west to east, it occurs in southem Senegal and the such as agricultural and pastoral intensification (Gra- Gambia; southern areas of Mali and Burkina Faso; ham 1969) and overgrazing around tube wells have northern Ghana, Togo, and Benin; northem Nigeria, destroyed a great deal of woody biomass. Careful Cameroon, and Central African Republic; southem management is needed if this class is to supply a parts of Chad and Sudan; and in northern Ethiopia. sustainable yield of fuelwood. The vegetation is mainly a rather open tree savanna of 51 Acacia Woodland Mosaic occurs mostly in 15to25metersinheight,orshrubsavanna.BothAcada southern Africa, where it covers large areas of eastern and Combretumspecies are common. A ground layer Botswana'and-the Namibian interior, as well as north- of annual and perennial grasses exists, which burns ern Transvaal and the fringes of South Africa's veld easily during the dry.season. grasslands. Extensive areas are also, found in the The growing stock for this class is less than 1,050 southern regions of Mozambique and Zimbabwe. million tonnes, with a sustainable yield exceeding 213 Generally this class consists of rather open woodland million tonnes. Agriculture and grazing have de- with trees up to 10 meters height, most commonly graded large areas of woodland. Fuelwood collection Acacia, Commiphora,Combrefum, and Terninalia spe- for cities such as Chartoum has left considerable areas cies. These woodlands have frequently undergone almost treeless (Lewis and Berry 1988). The current scrub invasion. fuelwood shortages and associated environmental EIn southem Africa this cluss is dominated by agri- degradation will almost certainly become worse at culture. Pastoralism has destroyed much of the woody present rates of extraction. biomass and ranching hasrestricted access. Productiv- 64 Sudanian Woodland forms another latitudinal ity is fairly low, with 35 million tonnes of sustainable belt across Africa, lying immediately to the south of yield from nearly 1,100 million tonnes of growing the Dry Sudanian Woodland (62). The belt is rather stock, so once again, exploitation requires management. scattered, but broadest in the region of the West Afr- 52 East African Low Woody Biomass Mosaic oc- can coast From the west, this cdass covers areas of curs mostly in a belt from northeastern Uganda to the Guinea-Bissau, Guinea, Mali, Cote d'Ivoire, Burlina highland region of southwestern Kenya, although Faso, Ghana, Togo, Benin, Nigeria, Cameroon, south- small outliers exist in the countries of the Hom. Much emnChad, northern Central African Republic, south- of this vegetation is Combretum small tree savanna, em Sudan, and small areas in the highlands of Ethio- becoming evergreen and semigreen bushland in the pia. This class corresponds to areas that White (1983) Kenyan highlands. With a growing stock estimated at classified as "Sudanian woodland with abundant - 399milliontonnes,producingnearly32milliontonnes Isoberlinia"and a mosaic of lowland rain forest and of sustainable yield, this class is locally important secondary grassland. Much of the area mnaybe de- Descriptionof Biomass Classes 27 scribed as derived savanna, ranging from closed can- shrubs tend to Iorm relatively dense stands separated opy savanna woodlands to thicket savannas. by grasslands or herbaceous wooded savanna Sudanian woodland contains a growing stock of (Laclav&re1980). nearly 1,184 million tonnes, producing a sustainable Guinean woodland has a growing stock estimated yield exceeding 391 million tonnes, the second highest at nearly 3,123 million tonnes, greater than all but four of all the classes. Disturbance has been low and the of the other classes, producing a sustainable yield of prospects for sustainable fuelwood extraction at pres- 256 million tonnes. ent rates are good. 76 Medium-Productivity West African Cultiva- 65 Moist Sudanian Woodland is scattered along tion and Forest Mosaic is the most extensive land the. south of the Sudanian woodland belt in coastal cover class in coastal West Africa. It occurs in every West Africa, spreading from central Guinea into cen- country of the region and forms a broad band from tral Africa. The largest area of this class straddles the Guinea-Bissau to southeastern Nigeria. This class con- border between Sudan and Central African Republic. tains renants of semideciduous humid tropical for- The zone ends in northern Uganda. Vegetation is gen- est in a mosaic with areas cleared for agriculture and erally an open woodland savanna with trees attaining timber. The mosaic typically contains both rain forest 15 meters in height. The most usual domiant tree and savanna species at its northern limits, where it species is Isoberliniadoka, and an understory of shrubs may represent an ecological transition from humid sometimes is present Growing stock is 1,887 million tropical forest and Guinean Woodland (74). tonnes, with a sustainable yield exceeding 282million Generally, forest and woodland dominate in areas tonnes. of low population density and clearance is more ex- 66 SeasonalMiomboWoodlandcovershugeareas tensive in heavily populated regions, especaally of central and East Africa between about 15 S and the around towns and cities. The mosaic has the fourth- equator. It is most extensive in northern Angola, largest growing stock of any class,- exceeding 3,641 southern Zaire, Zambia, Zimbabwe, Tanzania, million tonnes, coupled with the largest sustainable -Malawi, and Mozambique, and extends along the In- yield, nearly 561 million tonnes. Ongoing forest dear- dian Ocean coast from Beira in southern Mozambique ance makes this class an important supplier of fuel- to Port Elizabeth on the southern Cape. This class wood both locally and to deficit areas. covers a wide range of woodland types, the most 77 Highland Cultivation Mosaic is confined to common including Brachystegia, Julberardia, and Ethiopia, of which it covers about 17 percent. Found Isoberliniawoodland, often to 20 meters height, and on plateau areas between 2,000 and 3,000 meters ele- frequently with a woody understory. vation, it is the result of thousands of years of defores- Seasonal miombocontains the largest growing stock tation due to fuel collectin& grazing, and cultivation. of any class, exceeding 6,836 million tonres. Sustain- Large areas are now treeless, although land uses range able yield is nearly 138 million tonnes. Thisrepresents widely from dense cultivation to tree plantations, as a considerable potential for fuelwood exploitation, well as remnants of forest and woodland. Total grow- 67 Wet Miombo. Woodland is most extensive in ing stock is less than 1,350 million tonnes, but with a souther Lire, northern and centralAngola,northern sustainable yield less than 15 million tonnes. The region Z:ambia, southeastern Tanzania, and central Mozam- has long suffered from critical fuelwood shortages, and bique. Generally found in wetter areas with a lower it appears that these will continue and worserL seasonalitythanSeasonalMiomboWoodland(66),Wet 81 Mangrove grows extensively on the coasts of Miombo Woodland has a similar species composition, East, central, and West Africa, especially around river but with rather dense thickets that often form the estuaries. Local pressure on mangrove swamps is in- understory. Wet Miombo Woodland has a growing tense in many areas. Mangrove wood is excellent fuel stock of nearly 2,540 million tonnes, producing a sus- and is used for smoking fish, so many mangrove tainableyieldofmorethan43mnilliontonnes.Withfew stands are heavily exploited and depleted, despite exceptions, this class represents an important fuel- general protection by law. The inability of the satellite wood resource in the countries where it occurs. images to resolve very narrow fringes of mangrove 74 Guinean Woodland has a similar distribution swamp, notably on the East African coast, means that to the Moist Sudanian Woodland (65) already de- the figures for growing.stock (193 million tonnes) and scribed. It is most extensive in three main areas: (1) in sustainable yield (68 million tonnes) are almost cer- coastal West Africa, where it occurs in every country tainly underestimates.- except Liberia; (2) in Central African Republic and 82 Evergreen Forest mainly represents montane adjoinng areas of Caimeroon, northern Zaire, and forest vegetation. It occurs in a number of highland southen Chad; and (3) in the border region of south- areas, including the mountains of southem Tanzania em Sudan, northwestern Uganda, and northeastern and eastern Transvaal in South Africa, as well as the Zaire. Rainfall is fairly high in these areas, so trees and rift escarpment in eastern Zaire. These areas typically 28 Estimating WoodyBiomass in Sub-SaharanAfrica

experience high rainfall and humidity and encompass and constitutes a growing stock of about 1,540 million a wide range of both montane and lowland rain forest tomes. Sustainable yield is a little more than 39 mil- species. The growing stockfor theclass isl,310million lion tonnes. tonnes, wit a sustainable yield of more than 90 mit- 87 Ombrophilous HumidTropical Forest extends lion tonnes. Clearance has occurred in some areas, along the equator, covering vast areas in Zaire, Congo, with only the steepest slopes remaining forested. Gabon, Cameroon, Central African Republic, and Rio 85 Mesophilous Humid Tropical Forest is most MunLThereislittleseasonality,withthemeanannual extensive on the northem fringe of the equatorial and rainfall of 1,500 to 2,100 millimeters distributed fairly Ombrophilous Humid Tropical Forest (87), where it evenly through the year, and productivity is consis- covers large areas of Cameroon, Rio Muni, Gabon, tently high. The forest has a tall, closed canopy which Congo,CentralAfricanRepublic,andespeciallyZaire. may reach 45 meters in height. Most species are ever- South of the equatorial forest, this class occurs in a green, although a few deciduous species shed their broad swath along the west coast from Cabinda to leaves during the brief dry season. southern Gabon The mesophilous forests are rather The ombrophilous forests have a growing stock of more seasonal than the equatorial forests, showing a nearly 5,932 million tonnes, second only to the much more pronounced dry season, and correspond partly more extensiveSeasonalMiombo Woodland (66)to the to the drier Guineo-Congolian rain forest of White south, and a sustainable yield exceeding 150 million (1983).The range of species is wide, as is te degree of tonnes. Much of the remaining forest area throughout species domnmance. Thlis class contains about 2,850 Africa is protected within reserves. Much of the pres- million tonnes of growing stock, producing a sustain- ent equatorial forest area has been cultivated in the able yield of more than 72 million tornes. past, and the vegetation is secondary. Within some 86 HumidTropicalSwampForestformsanarrow reserves, older secondary forest may be indistin- strip near the equator, with areas around the western guishable from primary forest This enormous bio- shores of Lake Victoria in Tanzania and Uganda, and mass resource has been largely removed from pDten- in Zaire, Congo, southern Cameroon, and Gabon.- tial fuelwood reserves in the interest of science and Swamp forest covers up to 6 percent of central Africa tourism- 6 RegionalSummaries by Classof Biomass

This chapter summanzes physical characteristics, PhysicalCharacteristics, Population, and Resources population, resources, and the condition of woody biomnassfor each of the six regions examined in tis Rainfall in the region is markedly seasonal, with the study. For each region, a table presets (a) the esti-. humid season peaking in July and August and the mated surface area and percentage of the nine sum- principal biological production occung soon after. mary dasses of land cover, (b) the growing stock by In the semudesert regions, annual rainfall is only 100 summary land cover class, and (c) the sustainable to500nmillimetersayear.Evaporationrateisrapidand yield by summary land cover class. For a more de- water-holding capacity of the soils is smalL In the tailed review of the distribution and character of the south of the region, annual rainfall may exceed 1,000 woody biomass in each region, please refer to Part II millimeters. This, combined with high summer tem- where the 43 land cover dasses are discussed. peratures, produces favorable conditions for photo- synthetic activity and resultsi m the marked seasonal- The West African Sahel ity of the biomass. The north of the region is subject to periodic fluc- For the purpose of this study, the West African Sahel tuations of climate, of which the great drought of is bounded by the latitudes of IUDN to 2;3 N and the 1968-73 was an extreme. This significantly affects longitudes of 18" W to 24e B. The region includes the water availability. As a consequence, a mosaic of seven countries of Mauritania, Senegal, the Gambia, vegetation patterns exists, reflecting areas in which Burkina Faso, Mali, Niger, and Chad. The area is de- land is stressed. ImiLted to the north by the Sahara Desert, and all In the nortiem countries, distribution of the seden- countres have significant desert territory except.the tary human population is restricted to more produc- Gambia, Senegal, and Burkina Paso. five areas having greater and more predictable rain-

Table 6-1 Distribution of Summary Classes and Estimated VWoodyBiomass, West African Sahel Arna rozuingstock Sustainableyield- Million Thousand Summarycl kn? Perent tonnes Percent tinesperyear Percent 0 Desert 2,590,342 4931 0.00 0.00 0.00 0.00 1 Grassland 40,997 0.78 931 037 409.97 0.41 2 WoodedGrassland 981,080 18.68 323.76 12.96 9,810.80 9.84 3 Shrubland 0 0.00 0.00 0.00 0.00 0.00 4 Bushlandand Thicket 879,957 16.75 130.85 5.24 30,72252 30.80 5 LowWoody Biomass Mosaic 211 0.00 0.45 0.02 13.29 0.01 6 Woodland 73077 13.91 1,951.17 78.09 50,396.70 50.52 7 High WoodyBiomas Mosaic 8,326 0.16 14.02 0.56 158.19 0.16 8 Forest 2,793 0.05- 68.93 2.76 8236.56 8.26 Lakes 18,233 0.35 0.00 0.00 0.00 0.00 Total 5,16 100.00 2,498.49 100.00 99,74&03 100.00 Noht Detailsmay not add to totalsbecause of rounding Saun2 Tables8-1 to 8-7.

29 30 EsiminttingWoody Biomnis in Sub-SaharanAfrica

fall. Land use in the semidesert regions is largely Resources Institute 1986).(Ihe region doesnotexhibit pastoral, although significant permanent populations the rapid growth rates of other parts of Africa, such as exist along the Senegal and Niger rivers and their Kenya.) This increase, coupled with greater than 40 associated irrigation schemes. According to the PAO, percent of the population being 14 years of age or population density varies throughout the region, with younger, means that demographic pressure can only 1985 statistics showing 1.8 persons per sqqare kilome- increase. The demand for greater space for food pro- terinMauritania,contrasting with33.2inSenegaland duction results in degradation of land already ex- 56 to 59 in the Gambia (World Resources Institute ploited to its full potential. This can be seen in areas of 1986). Tlhese mean figures, however, cannot truly re- Senegal or in extensive migration like that occurring flect the possible demographic stress caused by the in Burkina Faso. population distribution. Discussion with the director of the Institut de Re- Relief and soil dearly have implications for biomass cherche en Biologie et Ecologie Tropicale (imsTr),based production. The plateaus of the southern Sahara and in Burkina Faso, confinns that the migration is partic- the Manding region of Guinea and Mali are reflected ularly significant. Areas of Sudanian woodland that in the classification produced from the imagery. Red- previously provided a more-than-adequate fuelwood brown soils of the south are endowed with greater resource now are being cleared for agriculture. capability of retaining water, contrasting with desert Research within the Sahelian zone by the Univer- soils and sands farther north. sity of Kano in northem Nigeria suggests three man- A review of the classes shown in table 6-1 discloses agement strategies for sustainable production of that Desert (Class 0) occupies 49 percent of the region, fuelwood (Cline-Cole and others 1987): (a) farmed including large areas of Mauritania, Mali, Niger, and parkland in which trees are retained, (b) shrubland Chad. Grassland (1) covers less than 1 percent but or fallow, and (c) forest reserves. This work also Wooded Grassland (2) covers 19 percent as a broad notes the diversity of use and calorific values of dif- latitudinal belt. No Shrubland (3) is recognized in this ferent species. region but Bushland and Thicket (4) covers 17percent. Accessibility to fuelwood in the most densely pop- Woodiland (6) covers 14 percent of the region and ulatedareasvariesthroughtheregioLn.Wheretreesare locally is important at the southem edge adjacent to retained to a significant extent, management is possi- the West African Coast region. Low Woody Biomass ble that recognizes diverse use for food and fodder, Mosaic (5), High Woody Biomass Mosaic (7), and constmction, pharmaceuticals, heating, and cooking. Forest (8) are almost completely absent from the West An assessment of woody biomass is not necessarily an Afican Sahel region. assessment of fuelwood, although all trees become fuelwood if no alternative exists. Conditionof Woody Biomass A significant contribution to growing stock comes from the Bushland and Thicket class, of which the Assessment of woody biomass in the West African dominant type is Saahel-Sudanian Acaca Wooded Sahel is problematic because of several difficulties in Bushland (44). It accounts for more than 130 million interpreting Normalized Difference Vegetation Index tonnes of growing stock and a sustainable yield of (NDvi) values in relation to biological activity. One 30 million tonnes, about 30 percent of the regional problem is that we cannot distinguish between herba- total (table 6-1). The Sudanian Woodlands (62, 64, ceous and woody biomass. In a region like the Sahel, and 65) are highly significant, at more than 1,900 which includes areas of limited tree cover and vast million tonnes of growing stock and 50 million areas of seasonal grassland, this is obviously signifi- tonnes sustainable yield. This group is most vulner- cant For example, in a study of the regeneration of able to the present population migration in the degraded Sudanian savanna during a 10-year period, south of the region. Bonkoungou, Bortoli, and Oudba (1988)show that the It should be remembered- that estimates for this grass Andropogongayanus forms 50 percent of the bio- region are particularly crude because of the paucity of mass. Another problem is our inability to distinguish data for herbaceous biomass and noncommercial between seasonal crops and natural wooded grass- wood. The Sudanian Woodlands in particular merit land, which produce similar phenologies. closer, coordinated study, with a more intensive local Human population density is much greater in the examination of woody biomass estimates linked to a southemportion of all the countries, exacerbated both finer resolution of remotely sensed imagery. Much by desertification andpopulation growth UnitedNa- work Is under way within organizations such as mnr, tions figures show that all Sahelian countries except the Centre Technique Forestier. Tropicale (arr), and the Gambia have a population growth rate exceeding the Institut de Recherche Agronomique du Niger 2 percent, and all rates are projected to increase (World (INRn). RegvionilSummaries 31

The West African Coast Conditionof WoodyBiomnass

Tfhe West African coastal region includes all of the The West African coastal states generally have ade- countries bordering the.Atlantic Ocean from Guinea- quate woody biomass, particularly for fuelwood and Bissau to Nigeria. Strong ecological and agricultural charcoaL Two countries, Liberia and Sierra Leone, arguments exist for this division. First, this region have only local problems of supply, due either to contains the humid tropical forest zone of West Africa dense population concentration, edaphic restriction and wet (Guinea) savanniawoodland. Second, cultiva- on tree growth, or land reservation. tion in the southern two-thirds of the region is donmi- The other countries all have a general decline north- nated by root and tuber crops, rice of both upland and ward in growing stock and sustainable yield. This swamp varieties, and plantation tree crops such as pattern results from the latitudinal disposition of land cocoa, coffee, rubber, and oil palm. Grazing systems cover classes across the region. The high-productivity and'dryland crops are restricted mainly to the north- Forest and H-igh Woody Biomass Mosaic classes are ermmost parts of the region. adjacent to the coast, the wet (Guinea) savanna wood- land is farther inldand,and the drier (Sudarnian) sa- Physical Characteristics,Population, and Resources vanina woodland thrives in the ntorthern part of the region. This pattern is a function of the mean annual Estimated woodfuel consumption in 1990 was ap- rainfall and the length of the wet season. proximiately 81 million air-dried tomnes (table 1-2). TIhemajority of growing stock and sustainable yield. Sustainble yield significantly exceeds this; therefore is in the High Woody Biomass Mosaic adjacent to the the region has a positive overall balance of woody coast, the Woodland, and the highly significant Man- biomass supply. Two problems exist, however, with grove class. Repeated cutting of the wood in the Hfigh both the actual s'upply and the potential supply. First, Woody BiLomassMosaic means that many trees and the northern part of the zone is dominated by dry shrubs continue to grow rapidly. To counter this rapid savannia woodland, from3which it is difficult to trans- annual growth, however, forest reservation and plan- port wood to large cities such as KCanoand Sokoto. tations probably restrict access to land more for two Second, muc-hwood from the Sudanian woodland is clamssethan for any others in the region: H-igh-Produc- converted into charcoal and transported to the large tivityWet African Cultivation and Forest Mosaic (75) coastal cities. and Medium-Productivity West African Cultivation In the wetter areas of higher productivity to the and Forest Mosaic (76). south, significant extraction of timber occurs. Such Guinean Woodland (74)includes 7.6 percent of the forest degradation probably has little negative impact growing stock and 1.8 percent of the sustainable yield. on the wood energy market and in fact may lead to a ApartfromGuinea,where extensive clearance of these local surplus of "waste wood that is sold or freey woodlands has been conducted in the Fouta jallon collected. Of course, local supply problems exist, such region, this zone is the least exploited of the main as those in central Sierra Leone, related to particularly biomnassclasses in the region. This situation could dense population concentrations, edaphic factors that change because of increasing population density or restrict tree growth, and reservation of forest and other increasing exploitation of the trees for fuelwood and types of land. charcoal in the Guinean woodland. A review of the classes in table 6-2 shows thatDesert TfheSudanian Woodlands (6Zto 65) encompass only (0) and Shrubland (3) are virtually absent from this 40 percent of the growing stoc-kand 17 percent of the region. Grassland (1) represents less than 2 percent sustainable yield (table 6-2).This suggests a currently and Wooded Grassland (2) less than 1 percent of the hiigh level of exploitation, probably attributable to region's land cover. Bushland and Thicket (4) covers 8 charcoal production for cities along the coast and to percent of the regiLon,principally in northern Nigeria. local demand. Comparison of growing stock with the Low Woody Biomass Mosaic (5) is relatively unim-. area covered by these woodlands reveals that they are portant and covers just 1 percent. Woodland (6) is an understocked. Consequently, woody biomass supply important category, covering 40 percent of the region problems undoubtedly.exist in these woodlands, par- in a broad belt from Guinea in the west to central ticularly where the population is concantrated and the Nigeria in the east Bordering this zone to the south is cultivation is intensive. the mzostextensive summary class, High Woody Bio- TIhemostnortherly largebiomass class in thisregion mass Mosaic (7), which represents 44 percent of the is Sahel-Sudanian AcaciaWocoded Bushl-and (44), regional land cover and is present in all countries. which is typically.Sahelian. Occurring only in north- Finally, Forest (8) covers only 3 percent of the region, em Nigeria, it represents just 0KSpercent of the grow- mainly in small coastal blocks. ing stock and about 2 percent of the sustainable yield. 32 EstimatingWoody Biomoss in Sub-SaharanAfrica

Table 6-2. Distribution of Summary Classes and Estimated Woody Biomass, West African Coast Area Growingstock Sustainableyield Million Thlousand Summaryclass km? Percent tonites Percent tonizesperyear Percent 0 Desert 475 0.02 0,00 0.00 0.00 0.00 I Grassland 38,415 1.88 .8.72 0.16 384.15 0.15 2 Wooded Grassland 17,706 0.87 5.84 0.11 177.06 0.07 3 Shrubland 0 0.00 0.00 0.00 0.00 0.00 4 Bushland and Thicket 167,832 8.22 30.79 0.57 5,808.49 226 5 Low Woody Biomass Mosaic 18,447 0.90 42.82 0.80 1,254.83 049 6 Woodland 809,981 39.69 2,162.52 40.34 43,683.43 16.99 7 High Wody Biomass Mosaic 906,252 44.40 1,526.13 28.47 17,218.79 6.70 8 Forest 64,615 3.17 1,583.73 29.54 188,656.05-. 73.35 Lakes 17,284 a.s 0.00 0.00 0.00 -0.00 Total 5,252,716 100.00 5,36055 100.00 257,182.80 100.00 Note Details may not add to totals because of rounding. Source:Tables 9-9 to 9-17.

This area has dense population concentrations (for mals. This is quite apart from its value in environmen- example, the Kano and Sokoto "close-settled" zones), tal maintenance of soil quality, as shade frees, and as and in these areas fuelwood supply is a significant a habitat for economically valuable wildlife. problem, exacerbatedby an overallshortage of woody biomass.Thisclassoffersthepoorestwoodfuelsupply Physical Characteristics, Population, in the region. and Resources

The Hom of Africa Woody biomass in this region reflects variations of climate. These are caused by seasonal variations in the Four countries constitute this region: Djibouti, Ethi- position of subtropical high-pressure cells; by the lat- opia, Sornalia, and Sudan. Although the population is itudinal extent of the region; by variations in altitude, overwhelmingly dependent on subsistence agricul- particularly in Ethiopia; and to a. limited extent by ture, commercial agriculture, or pastoralism, woody higher precipitation, which may be caused by proxin- biomass is vital to everyone in these countries, even ity to the sea. Although temperatures significantly those in urban areas. Woody biomass is essential as a influence the highland areas of Ethiopia and the fuel (it is locally available and relatively inexpensive), higher parts of the Equatoria region in Sudan, the as building and construction matenal, as material for main determinants of vegetation patterns are precipi- the construction of equipment, and as browse for ani- tation and seasonal variability.

Table 6-3. Distribution of Summary Casses and Estimated Woody Biomass, Hom of Africa Area Growingstock Sustainableyield Millior. Tlhousand Sunmary clss . kit? Percent tonnes Percent lonnesper year Percent 0 Desert 1,115,190 25.65 0.00 0.00 0.00 0.00 1 Grassland 133,952 3.08 30.41 0.65 1,339.52 0.98 2 Wooded Grassland 761,815 17.52 251.40 5.38 7,618.15 5.56 3 Shrubland 685 0.02 0.69 0.01 34.25 o.m 4 Bushland and Thicket 1,053,007 24.22 976.66 20.90 28,002.47 20.43 5 Low Woody Biomass Mosaic 106,656 2.45 229.51 4.91 6,719.33 4.90 6 Woodland 755,016 17.37 Z015.89 43.15 47,645.08 34.76 7 High Woody Biomass Mosaic 363,598 8.36 612.30 13.11 6,90836 5.04 8 Forest 52,695 1.21 555.24 11.88 38,797.79 28.31 Lakes 4,690 0.11 0.00 0.00 0.00 0.00 Total 4,347,304 100.00 4,67210 100.00 137,064.95 100iO. Notc Details may not add to totals because of rounding. Sourcc Tables 10-1to 10-4. RegionalSummaries 33

Except for deserts and small areas of tropical forest, vegetation in a zone radiating from the wellhead, almost all vegetation classes reflect the pronounced possibly extending several kilometers. This phenom- seasonality of precipitation, which includes one or two enon has been noted in central Sudan and in Somalia. dry seasons of differing length. In many of the classes, One unfortunate effect of heavy grazing has been to precipitation variations from year to year may pro- encourage development of unpalatable species. foundly influence plant cover, particularly when Clearance of trees for agriculture, either bush fal- prolonged drought is exacerbated by heavy human lowing or permanent agriculture, has reduced woody interference. biomass in damper areas of Sudan, Ethiopia, and So- Variation in soil and relief is important in some malia. This may lead to virtual elimination of tree classes of land cover because such variations deter- species unless trees are deliberately incorporated into mine the overall nature of the class. For example, the farming system. In bush-fallowing systems, cer- vegetation is influenced by the lateritic soils of south- tam desired tree species may be protected, but a re- ern Sudan, the dark, cracking clays and sands of cen- duced penod of fallow may suppress the successful tral Sudan, and the escarpments of Ethiopia. Within regeneration of trees. each class, variations of soil, relief, and drainage also Commercial timber extraction is selectively de- may locally affect biomass. structive of larger straight-boled trees which are A review of the classes (table 6-3) discloses that most common in forested areas. Complete removal Desert (Class 0) occupies about 26 percent of the re- of all large trees may follow in accessible areas. gion, including a significant portion of each country. Areas of higher population also may suffer loss of Grassland (1) covers 3 percent of the region and is trees and bushes through the extension of agricul- important mainly in Sudan. Wooded Grassland (2) of ture; this is notable in areas of coffee plantation in various types occupies nearly 18 percent of the region southwestem Ethiopia. and is present in eadh country, but is most extersive Buning of grassland as a method of encouraging inSudan. Shrubland (3) isnearly absenL Bushland and grass growth is widespread inwooded savanna grass- Thicket (4) occupies 24 percent of the area and is lands. Consequently, trees and bushes that are not fire important in Sudan, Ethiopia, and Somalia. resistant are ldlled off, whereas resistant species are Low Woody Biomass Mosaic (5) is confined to the encouraged. extreme south of the region and covers just 2 percent. Fuelwood collection is the other main cause of tree Woodland (6) covers 17 percent of the area and is most cover loss. It occurs in rural areas, but may be greatly important in Sudan and Ethiopia. High Woody Bio- increased by urban demand for wood or charcoal1 mass Mosaic (7) covers 8 percent of the region and is whichmaybe transportedhundreds of kilometers (for most important in Ethiopia. Forest (8) covers only 1 details, see the discussion of Class 22 in Chapter 10) percent of the region, largely in Ethiopia; it is signifi- Unlessadelhberatepolicyof managementof fuelwood cant because it may be associated with high biomass plantations is introduced near towns, tree removal potentiaL- spreads outward, particularly alongmotorable roads. This has been done in Ethiopia, where Eucalyptushas Conditionof Woody Biomass been planted for almost a century, and in parts of Somalia. For some decades throughout the region, concern has Kamweti (1984)has investigated the probable effect grown among both experts and laypersons about the of fuelwood collection up to the year 2000 in the East condition of natural biomass, both woody and non- African region, whidh inmludesEthiopia and Somalia. woody. In the drier regions of each country, biomass Most of Ethiopia and Somalia already suffer fuelwood conditionrelatestodesertification,detailsofwhichare deficit, with the most serious effect in the desert, dry considered inthe followmngdiscussion of specific land savanna, and especially the densely populated high- cover classes. In general, desertification is the degra- lands of Ethiopia. In Somalia, the problem is serious dation and possible elimination of biomass caused by throughout the country. sequences of unusually dry years, which have oc- In Ethiopia, at the present rate of deforestation, 1.76 curred approximately every 20 years in the present millionhectares of woodland will be lost by the year century. 2000, and 2.27 mnillionhectares of shrubland will be Thisclimiaticstressonvegetationiscompoundedby degraded. In Somalia, the main problem is degrada- intensified consumption of biomass through grazing tion of shrub; however, 13,000 hectares per year of and browsing by the animals of herders who have productive forest is being lost Comparable informa- been displaced from other degraded areas. Increasing tion is not available for Djibouti and Sudan, but population, both human and animaL no doubt con- clearly, what little forestremains in the formerisbeing tributes to the process. Tube wels focus grazing near devastated, and in the latter the effect of wood re- watering points, leading to severe deterioration of movalin the central area is catastrophic (for details see 34 EstimatingWoody Biornass in Sub-Snianton Africa

toexceed the locally available the discussion of Classes 21,22, 44, and 62 in Chapter biomassdepletionlikely 10). -sustainable supply. Whitney, Dufoumaud, and Murdk (1987)calculate Population, and Resources that 31,000 square kilometers of woodland are con- Physical Characteristics, suned as fuetwood each year in Sudan. Additional biomass in this large region is dif- pressures have occurred in parts of Sudan, Ethiopia, Estimating woody that the classes of land cover and Somalia as the result of famine and political un- ficult, so it is reassuring are similar to previously iden- rest. Refugees from both threats have concentrated in that we describe often In the humid tropical forest small areas of the tree countries, causing additional tified ecological zones. both sparse population and stress on fuelwood resources. In Sudan, areas particu- zone, areas exhibiting biomass often are a conjunction of larly affected are the eastern plains, the Red Sea Hills, plentiful woody domestic fuel is the main end east of El Obeid, western Darfur, and the Juba area. cause and effect. Because in this region, our discussion The Hom of Africa has experienced a great influx of use of woody biomass of scarce or potentially scarce refugees: 1.5 million people have moved from Ethio- focuses on areas pia to Somalia, Sudan, Kenya, and Djibouti since the woodfuel. of the region reflects variations of mnid-1970s.Civil wars in recent years in Sudan and Woody bionass with distance from the equator. Somalia have displaced more than 800,000refugees to climate associated forest areas of Africa occur in this neighboring countries (Black1989). Thus, the largest narrow beltextending 2 degrees north Inthe famine areas of eastemEthiopia (Tigre,Welo, region, within a of the equator. This area receives and Ogaden) and Sudan (Darfur, Kordofan, and Red and 2 degrees south other tropical rain forests (for Sea Hills), additional stress on vegetation is caused by less rainfall than many and Southeast Asia), but still sup- increased animal browsing and by human consump- example, Amazonia of closed forest This narrow tion of food derived from trees during famiine (for ports extensive tracts zone hais a brief dry season of about 2 example, see FAo/UN 1984). It is unclear if the present equatorial resettlement camps will permanently stress local bio- months. of this zone, where the dry season mass, as might occur when host governments attempt North and south 4 months, tiinner and usually decidu- to make the camps self-supportingby giving only land extends to 3 or occur. These are miombo as a contribution to refugee self-sufficiency.This is, of ous forests and woodlands south (part of the ZarbeziarL phy- course, an additional pressure on biomass resources. woodlands in the region) and Guinean and Sudanian For example, near Qala 'en Nahal, the largest Sudan- togeographical north. At the northern extremity of ese refugee settlement, the rate of deforestation has woodlands to the (10' N in Central African dramatically during the past decade. the central African region increased the dry season lasts at previous Ethiopian government's policy of re- Republic; 120N in Cameroon), The is that of the Sahel people to new settlements, particuarly in the least 6 months, and the vegetation locating ofthe regioninthehigh southern part of the country, undoubtedly did con- belt Atthesouthernextrenity (1f Sin Zaire), where the dry season tribute to deforestation of land cover classes which at plateau of Shaba months, the vegetation is open wood- present have reasonable reserves, such as Ombrophi- also extends to 6 as wooded savanna. lous Humid TropicalForest (87). land, often described On this general pattern of woody biomnassimposed equatorial climate, further varabil- Central Africa by variation of the ity results from relief, soils, and human interference. is most notable on the high ground Six countries constitute the central African region: The effect of relef Rift Valley in eastern Zaire and on the Cameroon, Central African Republic, Congo, Equato- of the westem Cameroon. (HeIre, persistent rial Guinea (Rio Munil), Gabon, and Zaire. Woody mountains of westen some small areas from being biomass is generally plentiful in central Africa, al- cloud cover precluded satellite imagery.) though important local exceptions occur, and a strong classified from the relief and latitudinal extent, geographical pattem reveals significant variation be- Because of its varied a complete spectrum of the vege- tween the relatively plentiful supplies of the Zaire Cameroon provides Africa, with humid tropical for- basin and the less-endowed areas of northern Camer- tation of intertropical woodland in the center, grass- oon, Central African Republic, and southern Zaire. est in the south, open in the north, and mountainous Locally, large urban populations can stress the supply land and bushland 1980). Relief also plays a role in the woodybiomass,asituationrecognizedincitiessuch forest (Laclav&re of south of the Zaire Basin, Brazzaville, and Ponte Noire along the extensive plateau areas to the as Kinshasa, reflects the extensive terrain above Zaire River and Kolwezi and Lubumbashi in the where temperature Away from the narrow belt of humid southern part of Zaire (Malaisse and Binzangi 1985). 1,000 meters. interplay of the relief with the pre- Only in a few areas like these, however; is woody tropical forest. the RegionalSummaries 35

Table 6-4. Distribution of Summary Classes and Estimated Woody Biomass, Central Africa Area Growingstock Sustainableyield Million Thousand Suimmaryclass km2 Percenit toines Percent lannesper year Percent 0 Desert 105 0.00 0.00 0.00 0.00 0.00 1 Grassland 17,336 0.44 3.94 0.01 173.36 0.01 2 Wooded Grassland 41,575- 1.05 12.05 0.04 415.75 0.02 3 Shrubland 7,430 0.19 7.43 0.03 371.50 0.02 4 Bushland and Thicket 49,797 1.26 71. 20.90 1,200.66 0.05 5 Low Woody Biomass Mosaic 5,111 0.13 11.03 0.04 321.99 0.01 6 Woodland 1,620,272 40.93 9,31156 33.25 137,550.85 5.78 7 High Woody Biomass Mosaic 645,098 16.30 1,058.39 3.78 12,256.86 0.52 8 Forest 1,550,884 39.18 17,525.69 62.59 2,226,336.80 93.60 Lakes 20,868 0.53 0.00 0.00 0.00 0.00 Total 3,958,476 100.00 28,001.17 100.00 2,378,627.77 100.00 Not Detailsmay not add to totalsbecause of rounding. SourmcTables 11-1 to 11-6. cipitation variation from year to year can produce of 18.8 percent. They observe that some vegetation much greater spatial and temporal variation in the typeshadalmostdisappearedlocally,indudingdense plant cover. riparian forest Soil types and conditions can influence extensive Detailed studies like this are rare, but the extent tracts where the woody biomass is less than would be of human impact is not Even in Gabon, 80 percent expected for central Africa. Examples include Veld of which formerly was covered with forest, large Grassland (11) on the Kalahari sands of Quaternary areas now are recognized as High Woody Biomass ageinsouthemZaireandEdaphicWoodedGrassland Mosaic. Here, small-scale clearance by traditional (25) in Congo on "drought/' plateau soils, despite means of shifting cultivation has significantly recelving more rainfall on average than the adjacent changed the nature of the forest. However, no dis- humid tropical forest. quiet need yet be felt about Gabon regarding woody A review of the classes in table 6-4 discloses that the biomass supply (Catinot 1978). Cultivation and lower woody biomass summary classes are either not forest mosaic is an important component of land represented or occur only as very restricted land cov- cover, accounting for 16 percent of the area of cen- ers. Desert () is not present in the region at all; Grass- tral Africa (table 6-4), commonly occurring at the land (1) covers less than half of 1 percent; Wooded margin of the forest zone where it represents human Grassland (2) covers 1 percent; Shrubland (3) and Low encroachnent and modification. Woody Biomass Mosaic (5) are nearly absent; and Bushland and Thicket (4) covers just over 1 percent. By East Africa contrast, Woodland (6) covers 41 percent of the region and is an important fuelwood reserve in many of the Five countries constitute this region: Rwanda, more populated areas High Woody Biomass Mosaic Burundi, Uganda, Kenya, and Tanzania. (7) covers 16 percent and Forest (8) covers 39 percent in a broad swath along the equator, presenting Physical Characteristics, Population, and Resources Africa's best-endowed woody biomass reserve. Household fuelaccountsfor90percent of all wooduse Condition of Woody Bionass in this region. With an annual average per capita consumption of 1 cubic meter a person, coupled with Even here, in the African region having the most plen- an annual average population growth rate exceeding tiful woody biomass, reference often is made to the 3 percent, it is not surprising that concern exists re- profound influence of human interference on the land garding dwindling woody biomass. At first, attention cover. This is illustrated by data collected by Milaisse focused on semiarid regions of obvious scarcity, par- and Binzangi (1985) for an area 1 degree of latitude by ticularly along roadsides. More recently, attention has 1 degree of longitude, centered on Lubumbashi in focused more logically on high-potential arid areas soutiem Zaire. These authors estimate that, since the where the majority of the population lives and where beginning of the century, the retreat of woodland and the greatest demand exists. This refocusing has led to forest involved 21.6 percent of the area (212,162 hect- the design of projects to reduce the problem of fuel- ares), with an associated diminution of wood reserves wood scarcity within areas of high potentiaL 36 EstinmntingWoody Biontass in Sub-SharaniAJfica

Table 6-5. Distribution of Summary Classes and Estimated Woody Biomass, East Africa Ana Growihagslock Suaslainablcield .Million------Tlhousand SuJl)mmanjclnss Permet 1011115ens Percentt Ionniesperyear Percenpt 0 Desert 14,913 0.83 0.00 0.00 0.00 0.00 I Grassland 6,059 0.34 1.38 0.02 60.59 0.03 2 Wooded Grassland 142,908 7.95 38.87 0.60 1,429.08 0.62 3 Shrubland 34,462 1.92 34.24 0.53 1,723.10 0.75 4 Bushlandand Thicket 490,118 27.25 752.02 11.61 10,296.90 4.50 5 LowWoody Biomass Mosaic 146,914 8.17 320.85 4.95 9,255.58 4.04 6 Woodland 526,003 29.24 3,581.07 55.27 50,304.67 21.97 7 High WoodyBiomass Mosaic 140,220 7.80 194.17 3.00 2,664.18 1.16 8 Forest 202,455 1126 1,556.89 24.03 153,265.44 66.93 Lakes 94,588 5.26 0.00 0.00 O.00 0.00 Total 1,798,640 100.00 6,479.49 ioo.oo 228,999.54 100.00 Moae.Details may not add to totalsbecause of rounding. Source:Tables 12-1 to 12-5.

The situation, however, is not simple. First, critical Because the satellite images are intended to give a fuelwood shortages exist primarily around towns in detailed view of vegetation on a regional scale, the the more arid areas, including the rain shadow of the resolution is insufficient to record the often dramatic coast, rather than in any particular rural production changes in forest type caused by changing altitude. system. Second, although wood scarcities are obvious Hence, the images fail to record Montane Forest (84) in landscapes as one drives through them, what one insuch areas as MountlKilimanjaro andMountKenya. sees is wholesale cutting for charcoal production in Although these ambiguities deserve recognition, response to the demand for urban energy-an arterial Montane Forest is of little value as available woody process closely related to principal transport routes. biomass. It not ordy is physically inaccessible, but Third, although fuetwood constitutes most of the remaining Montane Forest generally is strictly pro- wood consumed, this wood is waste wood-it is a tected by government. Fortunately, in light of their by-product of woody biomass being used for many immense scientific value, these sites have been well other purposes, including fodder. Finally, significant documentedelsewhere. evidence exists that land privatization or greater con- A similar problem arose in tte mapping of exten- trol by- village communities leads to significant in- sive M-ngrove (81) forest, which lines much of the caeases in woody biomass stocking because it ceases East African coast. For most of its length, Mangrove tobeafree good accessible to all. This occursin poorly forest is too narrow to be resolved at the mapping controlledandmanagedgovernment"forests,"which scale used here, apart from the area around large often are treated as commons. riverinlets. Although more accessible than Montane Estimating woody biomass production in East Af- Forest, as well as being an excellent source of wood ricais particularly difficult, especially from large-scale for charcoal manufacture, the value of mangrove as inagery, for two reasons. First, the East African bio- a source of fuelwood is also limited because of mass landscape is made up of ecological niches in frequent protection. which altitude, not spatial variation, determines A review of the classes in table 6-5 discloses that growing stock and annual productivity. Second, on many different land covers are important in this re- this altitudinal mosaic, which ranges from equatorial gion. Desert (0) and Grassland (1) together cover only glaciers to desert, a complex series of production sys- about 1 percenl of the region, but Wooded Grassland tens exists, from pastoralism to modern mnonocrop- (2) covers 8 percent and is important in northern ping agriculture. These systems involve sophisticated Kenya. Shrubland (3) covers 2 percent of the region, traditional technologies of dry land farming as well as mainly in eastern Kenya. Bushland and Thicket (4) intensiveirrigationforhighvalue-addedexportcrops. occupies a broad area in eastern Kenya and central The phenology of woody biomass generally shows a Tanzania, covering 27 percent of the region- Low marked seasonality, which reflects the bimodal distri- Woody Biomass Mosaic (5) covers 8 percent, mainly bution of annual rainfall. in western Kenya and Uganda. Woodland (6) forms The use of satellite imagery created problems in the most extensive class at 29 percent and is distrib- mapping of the forested areas in this region. The most uted in the west and south of the region. High Woody extensive type of forest in East Afica is Evergreen Biomass Mosaic (7) covers 8 percent and Forest (8) Forest (82),mostly situatedin the highlands of Kenya. covers 11 percent of the region; they are confined RegionalSimniauics 37 mainly to areas imnediately north and west of Lake Tanzania and significant areas of Rwanda and Victoria. Burundi. One woodland type, however, Moist Sudan- ian Woodland (65), occurs predominantly in the Conditionof WoodyBiomnass northern part of Uganda. These open woodland areas have a growing stock of more than 40 million tonnes, At a general level, the figures for growing stock reveal nearly 1 percent of the regional total. The remaining the characteristic vegetation of the three larger coun- woodland classes occur principally in Tanzania. tries of East Africa-woodland in Tanzania, bushland EastemTanzaniahas the main block of Wet Mionzbo in Kenya, and the mosaic of cultivation, forest rem- Woodland (67), with outliers scattered throughout nant, and derived wooded grassland in Uganda. Of Tanzania as well as Rwanda, Burundi, and southwest- the main classes of land cover, the first significant em Uganda. The growing stock of Wet MionrboWood- growing stock is Semidesert Wooded Grassland (21), land occurs mainly in Tanzania (1,272million tonnes), which dominates the arid north of Kenya. Despite its followed by Uganda (126million tonnes), Rwanda (28 large extent, the growing stock of this class is only 34 million tonnes), and Burundi (22 million tonnes). million tonnes, less than1 percent of the regional total. Seasonal Miombo Woodland (66) dominates the An important class in southern Kenya and northern western third of Tanzania, again with outliers Tanzania is Transitional Wooded Grassland (24). It throughout the country and, to a lesser extent, in the has a growing stock of nearly 1.8 million tonnes, more other countries of East Africa. With more than one- than two-thirds of which is in Tanzania. This repre- fifth of the entire regional growing stock, Seasonal sents 0.03 percent of the regional growing stock, and Miombo Woodland accounts for more biomass than the class produces 0.13percent of the regional sustain- any other class in East Africa. The vast majority of the able yield. growing stock is in Tanzania (1,872 million tonnes), Bushy Shrubland (33) is locally quite important, although the class is locally important in Burundi (60 although the greatest area is largely within the protec- million tomnes), southwestern Uganda (31 miUion don of Aberdare National Park in the highlands of tonnes), Kenya. (25 million tonnes), and Rwanda (12 southern Kenya. These relatively small areas have a million tonnes). combined growing stock of more than 32 million TheHighWoodyBiomassMosaicismostimportant tonnes, with two-thirds in Kenya and most of the in Uganda and southwestern Kenya, although signif- remainderinTanzania.Sustainableyieldis0.7percent icant areas exist in the highlands of Tanzania. The of the regional totaL Guinean Woodland (74) is especially common in Dry Acacia-CommiphoraBushland and Thicket (41) northwestern Uganda, whereas the center of the coun- covers huge dry areas of the region, especially eastern try is predominantly a Cultivation and Forest Re- Kenya and the steppes of nortiern Tanzania. Of a growth Mosaic (73).Evergreen Woodland Mosaic (71) growing stock of 359 million tonnes, 298 million are in is restricted to the moister parts of the region, notably Kenya, with 50 million of the remainder in Tanzania. the Kenyan highlands, the mountains north of Lake This class constitutes 5.5 percent of the regional grow- Malawi, the Lake Victoria Basin, and the coastal and ing stock. A rather smaller area is covered by Moist offshore islands of Tanzania. Acacda-CommiphoraBushland and Thicket (43),which Guinean Woodland has a growing stock of 35 mil- forms a large triangular block in the center of Tanza- lion torunes,producing only 0.45 percent of the sus- nia, with significant outliers in all of the other coun- tainable yield in Uganda, with 3.25 percent of the tries. Despite its size, the growing stock of this land growing stock. The Cultivation and Forest Regrowth cover class is almost twice that of the drier bushland, Mosaic of central Uganda is a little more productive, with 294 million tonnes in Tanzania and 66 mnillion with 1 percent of the Ugandan sustainable yield on 7.4 tornes in Kenya. Similarly, the sustainable yield of this percent of the growing stock. Uganda holds 72 million moister bushland is much greater, accotuting for a tonnes of growing stock, with the remainder in higher percentage of the regional sustainable yield. Tanzania. The East African Low Woody Biomass Mosaic (52) The forests of East Africa occur largely in the Lake covers much of northeastern Uganda and much of Victoria Basin of southern Uganda and in the high- southwestern Kenya. This class has most of its grow- lands of the other countries. The Montane Forest class ingstock inKenya-about 11 million tonnes, with the (84)ismostextensive in thehighlands of Kenya, where remaining 70 million tonnes in Uganda. The produc- the growing stock is 29.7 million tonnes. The remain- tivity is similar in the two countries, with the com- der of this class is in Uganda, where the Montane bined sustainable yield nearly5 percentof the regional Forest of the Lake Victoria escarpment contains a total. growing stock of 13.5 million tonnes. Productivity is Perhaps the most important biomass resource is the high, as in most of the forest regions, which account extensive miombowoodland that dominates much of for 67 percent of the regional sustainable yield. 38 EstimatingWoody Biomnass in SUb-Sahnamn Africa

Coastal and GaUery Forest (83) occurs mostly in Southern Africa Kenya and Tanzania, with much smaller areas in Uganda and Burundi. The growing stock of nearly 150 For the purpose of this study, southem Africa is that million tonnes includes 93 million in Kenya and 49 portion of the continent,south of Zaire and Tanzania, million in Tanzania. Overall, they represent 3.5 per- excluding the snall Angolan enclave of Cabinda. Its cent of the regional sustainable yield and 2.3 percent land area is nearly 6 miltion square kilometers. of the growing stock. Most Evergreen Forest (82) growing stock is in Tanzania, with 660 million tonnes, PlhysicalCharacteristics, Population, and Resources although theothercountrieseachhavestocksbetween about 17 million and 41 million tonnes. Much of this All eight of the sununary classes of land cover used in is physically inaccessible, and large areas of East this study occur in southem Africa, where we have Africa's dwindling forests are protected. divided them further into nineteen subdivisions. The majority of Mesophilous Humid Tropical For- These nineteen classes are based on vegetation phe- est (85) is in Uganda, with a growing stock of about nology;productivity, andland cover, the floristiccom- 172 miion tonnes.The remaining 10 million tonnes is position being less important. Consequently, some in Kenya, largely within the Kakamega forest north- classes incorporate a variety of vegetation types that east of Lake Victoria, which is uniquebecause i is the have been identified as distinct floristic units by au- only remaining moist tropical forest, in Kenya. The thors such as Werger (1978) and White (1983) but Lake Victoria Basin has been heavily cultivated, and which we have related by phenology, productivity, the indigenous forest, representing the eastem periph- and biomass. Our land cover dasses, however, are ery of the Guineo-Congolian rain forest belt, exists more appropriate for appraisal of fuelwood resources mainly in a-mosaic of secondary savanna and farm- than previously defined floristic mapping units. land. The growing stock is 2.8 percent of the regional A review of the classes in table 6-6 shows that Desert total and sustainable yield is 9.3 percent. (0) occupies nearly 6 percent of the region, being con- Humid Tropical Swamp Forest (86) is restricted to fined largely to the westem coastalstrip fromsouthem Uganda, where it occurs extensively on the western Angola to South Africa. Grassland (1) covers 6 percent shore of Lake Victoria and elsewhere. The growing of the region and Wooded Grassland (2) covers 11 stock exceeds 18 million tonnes, representing 0.2 per- percent; both are important classes in South Africa, cent of the East African total and 0.3 percent of the Botswana, and Naniubia. Shrubland (3) covers nearly sustainable yield for the region. The Ombrophilous 11 percent and is important in the same countries. Humid Tropical Forest (87) is much more extensive, Bushland and Thicket (4)-covers 8 percent and Low with a growing stock of 347 mnillion tonnes in Uganda Woody Biomass Mosaic (5) covers 9 percent Wood- and lesser amounts of 37 million in Kenya and 9 land (6) is by far the most extensive class, blanketing million in Tanzania In Uganda, this class is a mosaic 38 percent of the region with a broadly northem and ofcultivated land and remnants of the drier peripheral eastem distribution from Angola to Mozambique. semi-evergreen Guineo-Congolian rain forest of High Woody Biomass Mosaic (7) and Forest (8) each White (1983). cover 5 percent of the region.

Table 6-6. Distribution of Summary Classes and Estimated Woody Biomass, Southem Africa Area Growingstock Sustainableyield Million Thousand Summary class A?n2 Percent lonnes Percent tonnesper year Percent O Desert 350,529 5.91 0.00 0.00 0.00 a.oo 1 Grassland 356,008 6.00 80.81 0.43 3,560.08 0.79 2 Wooded Grassland 667,018 1124 43.88 0.23 6,670.18 1.49 3 Shrubland 636,665 10.73 514.69 2.76 31,833.25 7.10 4 Bushland and Thicket 471,255 7.94 800.45 4.29 9,89636 2.21 5 Low Woody Biomass Mosaic 519,891 8.76 1,160.41 6.21 32,753.13 7.31 6 Woodland 2,243,923 37.82 13,789.88 73.83 195,602.60 43.63 7 High Woody Biomass Mosaic 329,029 5.54 359.96 1.93 6,251.55 1.39 8 Forest 317,803 5.36 1,928.39 10.32 161,784.40 36.08 Lakes 41,681 0.70 0.00 0.00 0.00 0.00 Total 5,933,80 100.00 18,678.47 100.00 448,351.55 100.00 -Note Detailsmay not add to totalsbecause of rounding.. Sourre:Tables 13-1 to 13-10. RegionalSummarIes 39

Conditionof WoodyBiomnass viding dry-season fodder, construction poles, furni- ture, tools,habitat for game, mulch to enrich the soil, This study extends the work on biomassin the SADC and protectionagainst wind and water erosion,This area described in tiTcFoundation (1987)and Milling- exerts considerable pressure on- trees and smaller ton and others (1989).As explained in the methodol- woody plants in all densely populated parts of soutl- ogy, theNDVI wecreused as thebasis of classificationfor em Africa.It is especiallynoticeable in the semiarid both of these studies and in the present work.Th NDVI arc of low woody biomass that stretches from south- indicatemorethan justwoodproduction,considering westem Angola through Namibia, across southem all plant material,including leaves, grasses,herbs, and Zambiaand Botswana,and into southem Zimbabwe crops, as wellas wood. Large areas of southem Africa and SouthAfrica. are cultivated,often by large commercialagricultural Another zone of lesser woody biomass resource, enterprises, and this poses problems in estimating although less obvious, is discemible from westem available woody biomass growing stock and produc- Mozambique through Zimbabwe, Zambia, and tivity. The risk also exists of overestimating fuclwood Malawi into Tanzania. This wide "dry-zone corridor" yields if the accessibility factor is not considered, for has a basis in topography and climate; for example, example in the case of areas reserved by govemment southwestem Mozambique is drier and the Luangwa and national parks. Valley in eastem Zambia is lower and drier. Much of Commercial forestry, such as that in South Africa this zone's raison d'etre, however, seems to be in local and Swaziland, also may give a false impression of the soils and drainage and, more important, in the popu- availability of fuelwood. Ideally, avaiability should lation pressure on woody resources. Therefore, this be evaluated using detailed local or regional informa- z&neneeds to be examined more closely at a national tion and fieldwork. Although some of this typeof data and regional level. is incorporated herein, the regional information islim- The following list synopsizes the distribution of ited, and the scale of this study meant that field check- summary classes in the region: ing could be undertaken only in selected areas of 0 Desert covers nearly 6 percent of southern Africa fuelwood having high and low potential. and occurs in the southwest as the Namib Desert, as On abroad, regional scale, the pattern of land cover part of the Great Karroo of South Africa, and in the groupings in this study resembles that of biogeo- driest parts of theKalahari Desert in Botswana. graphical studies (for example, Werger 1978)because 1, Grassland also covers nearly 6 percent of the many of the influencing factors-aresimilar. For exam- region and includes the Veld Grassland (11) of the ple, the regional pattem of land cover groupings interior South African plateaus and the Montane closely resembles the regionalpatternof meanannual Grassland and Heathland (14) of the southern precipitation (figure 7-1). These corresponding pat- DrakensbergMountains. terns range from the Namib Desert (Class 0), which 2 Wooded Grassland is represented by Transi- has less than 100millimeters of precipitation a year, to tional Wooded Grassland (24),covering 11 percent of the extensive biomass and high-productivity areas in the land area but containing only 0.23 percent of the the north and east, where precipitation exceeds 1,000 woody:growing stock (table 6-6). It occurs mostly on millimeters annually. fine-textured soils in areas experiencing approxi- Numerous environmental factors also influence the mately 400 to 800 millimeters of rainfall a year, in patternsdisplayed,however.Werger(1978)pointsout widely vaned locations but mainly in Namibia, that climate and topography are the basic determi- eastem Botswana, southern Zimbabwe, southern Mo- nants of vegetation structure, biomass, and productiv- zambique, northern Transvaal, and in patches ity in southem Africa. This is reflected in this study, as throughout the remainder of South Africa, often on the attested by a comparison of the maps depicting south- fringes of the veld. em African biomass, rainfall, and topography. The 3 Shrubland is relatively important in southem subdivision of land cover classes, however, is further Africa, coverng nearly 11 percent of the region but affected on a smaller scale by local factors, of which containing only about 2.8 percent of the growing soils, drainage, and land use are the most important. stock. More significantly, Shrubland accounts for 7.1 The impact of human population growth is evident percent of the region's sustainable yield. It indudes from the different land use pressures and from the the small class Veld Shrubland and Cultivation (31)of clearance of woody vegetation. n rural areas, people Cape Province; the large classes of Fill Shrubland (32) rely mostly on wood from trees and bushes for house- and Bushy Shrubland (33), both of which largely hold fuel, and the demand for urban energy promotes fringe the Namib Desert area; the KCalahariShrubland cutting for charcoal production on a much more dev- (34), which occurs mostly in southeastern Namibia, astating scale. Woody biomass is also part of the inte- northem Cape Province, and southwestern Botswana; grated production system of the peasant farmer, pro- and Wooded Shrubland (35), which occurs largely in 40 EstitmatingWoody Biomass in Sibd-SaharanAfilcn central Cape Province, on higher ground east of the greater rainfallalong the southeastem coast of South Namib Desert,and on the slightlywetter fringesof the Africaand Mozambique. KalahariDesert. 7 High Woody Biomass Mosaic is represented 4 Bushland and Thicket coversnearly 8 percentof by two classes,covering about 5 percent of southern southern Africa,and representsabout 4 percentof the Africa but including only about 2 percent of the growing stock.It is mostly representedby MoistAca- subcontinent's growing stock. Cultivatiun and For- cia-CominiploraBushland and Thicket (43).This class est/Woodland Mosaic (72) includes many high- occurs as a broken arc from southern Angola and productivity (although not always very woody) bio- northem Namibia through parts of Botswana,Zam- mass areas,associated with areas of greater moisture bia, Malawi Zirnbabwe, and Mozambiqueto South and cultivationzones, often occurringin areas of un- Africaand Swaziland, with its largest continuousoc- usual drainage characteristicssuch as the Okavango currence in Transvaal and Natal. Bushland and Delta in Botswana.Evergreen Woodland Mosaic (71) Thicket is often related to particular soils or land occursmainly in south-centralAngola and along the forms, or to regenerative phases followingexploita- coastof central Mozambique. tion. The much smaller area of FynbosThicket (42) is 8 Forest has only one representativein southem confmed to small areas of the coastalranges of Cape Africa-Evergreen Forest (82), which covers more Provincein SouthAfrica. than 5 percent of the land area and includes dense 5 Low Woody Biomass Mosaic covers nearly 9 montane forest as well as commercialforested areas. percent of southern Africa and indudes about 6 Theseareas representabout 10 percentof the growing percent of the growing stock It occurs in Namibia stockof southernAfrica, and 36 percentof the sustain- and Botswanaand is scattered throughout southem able yield. Angola, eastern and southem Zambia, Zimbabwe, The proportion of woody biomass in these sum- and southeastern Mozambique, as well as in South mary classesmostly increases from Class 0 through Africa. ClassB, although exceptions exist. Classes Oto3 clearly 6 Woodland dominates nearly 38 percent of the have very limitedfuelwood potential.In Clkss4, the continent south of Zaire and Tanzania and has large rateof exploitationcaneasilyexceedproductbvity.The woody biomass reserves representing 74 percent of Low WoodyBiomass Mosaic (Class 5) can be import- southern Africa'sgrowing stock It extends acrossthe ant locally,often coincidentwith dense rural popula- continent from Angola to Mozambique,generally tions and in need of carefulmanagement. modulating density according to conditions, from The large Woodland group (6) clearly includes a Open Woodland (61), through; Seasonal Miombo largeproportionofthesubcontinent'swoodybiomass Woodland (66), to- Wet MiomboWoodland (67). resources,butgreatvariationoccursinactualproduc- Miombowoodland is related to moist, frost-free or tivity and availabilityof fuelwood. The High Woody nearly frost-freetropical conditions,and it doniinates BiomassMosaic (7) includes some cultivated areas of the northern part of this region, with densityvarying little woody biomass stock, but also includes large accordingto seasonalityofprecipitation, edaphic con- areas of dense woodland having high productivity dition, and degree of huLmaninterference. The group, and fuelwoodpotentiaL Forestsare among the most however, also includes wann, temperate woodland productivewoody biomassclasses of southem Africa, (part of Class67) and tropicalcoastal woodlands (part but often include areas that have accessibilityprob- of Class66). These occur respectivelyin the areas of lemsbecauseofremotenessorcommercialownership. 7 Conclusionsand Future Directions

The products of this study are (a) maps showing riparian vegetation on narrow flood plains, narrow classes of land cover (defined by their woody bio- beltsoflandcovercontrolledbyaltitudeinEastAfrica mass),Cb)adatabaseofwoodybiomassgrowingstock and the Ethiopian Highlands, and the individual ele- and sustainable yield, and (c) maps of growing stock ments of cultivation mosaic (Summary Classes 5.and and sustainable yield for Sub-Saharan Africa. 7). The level of detail in our study is adequate for an Throughout this volume we have stressed that this initial situational overview intended for determining study has been a first attempt to cost-effectively pro- policy objectives, but for planning purposes it is not duce a continent-wide view of the woody biomass adequate. situation in Sub-Saharan Africa. The maps and data An extensive search of the secondary literature con- base are available for strategic planning, including the firmed the lack of data on woody biomass supply. priority designation of areas requiring woodfuel sup- Much of this literature has its origin in forestry and ply enhancement. This should enable use of such data therefore concems commercial woody species. But. for maldng better-informed decisions about stressed other end uses in addition to energy and commercial areas. These areas will require more intensive assess- timbe are important in supply-side estimates and ment, coupled with surveys of woodfuel demand, to should be considered. yield a better understanding of how to manage the Also, this work does not consider agricultural resi- fuelwood resource. dues and herbaceous biomass. Not only are these an A benefit of conducting a survey at this scale is the energy resource, particularly in arid and semiarid ability to compare areas at reconnaissance level, so areas such as the SaheL but crops and herbaceous that extrapolations based oni ecology can be made plants contribute to the NDvL Future work to upgrade from areas of plentiful data to areas where data are the quality of data bases such as these should involve scarce or absenL From this study it is clear that a such considerations. pressing need exists to develop among nations a more A positive outcome of our research is that the inte- harmonized strategy for woody biomass estimation. gration of the data base and land cover maps to pro- Another benefit of this study will be inreased duce maps of growing stock and sustainable yield awareness of the potential of AVHRRimagery to allow (figures 7-1 and 7-2) does begin to define areas in biomass assessment at the regional level, when com- whichproblemsof supplymayexistorbenascent.The bined with secondary data or field surveys. This presence of low estmates within or adjacent to areas method affords an impression of the woody biomass of greater biomass suggests areas where early action situation in relation to consumption. It also indicates should be taken to confirm the level of supply. Exam- where more intensive investigations are needed, to ples of such areas are the West African Sahel and the support meaningful intervention to manage the dryzonecorridoradjoiningpartsofeastemandsouth-* woody biomass resource. era Africa. Clearly, use of AVHRRNDvi data at a spatial resolu- Early action could take the form of further mapping tion of 8 kilometers restricted our identification and from imagery that has both a finer spatial resolution mapping to broadly defined classes of land cover. and a continuous time sequence of data. Other early Small classes having a distribution restricted to nar- response could mean improving the quality of the row belts or small parcels of land use were unlikely field data for the data base. Studies based in regions to be identified. Examples include the very narrow like those just identified, where improvement in the belt of mangrove along the Indian Ocean coast, estimate of wood supply is needed, should include at

41 42 EslintalingWoody Bionias in Sub-Slaiarap;Africn

F:gure 7-1 Growing Stock for Sub-Saharan Africa, 1986

ISO I ~~~~~~~~~~~~~~~~~~~~~~~~45*

.1 0 ~~ ~ ~ ~ ~ ~ ~~~~~~3

*~~K' ' /..

.. S-/X--' '1E,<' V -..

GrowingsLock J'A

More han 100.1 3 50.1 - 100.0 .20.1 - 50.0 5.1-20.0L 0.0- 5.0

30. 3' 10,0 20,0 p ICO2D Is, - is, 30 4 -.

the design stage a common methodology deived cation of the present study usingAvHRRdata having from the findings of this projecL a finer resolution. Analysis at the regional level, We have identified four specific issues for future however, requires multisensor land resource sate- mapping of land cover for woody biomass asses- fite iimagery of finer resolution (for example, Land- sment. They are: sat Thematic Mapper) to provide maps of better detail for energy planners. Such work is already Spatial resolution of the maps needs to be improvedfor being carried out in Pakistan by ESMAP in cornunc- pla-nningpurposes. We are not advocating the repli- tion with the Ministry of Planning (Energy Wing). Conclusious and Fulire Directions 43

Figure 7-2. Sustainable Yield for Sub-Saharan Africa, 1986

-'a-~~~~~~~~~~~~~~~~~~~~~~~~5 -~ ~~~/ r S

.,~~ .J.0 I -'''1'-'p7' --. <:'

* ~~ -... ,~~~* I a.

:~~~~~~~~~~~**~ *4' Ia :~~ ;91!ll>I(V

Sutaiale yied)

M0 :r t0h :5 4

0-51-1.00 -\x- 0.11-0.50 -\7 g.,

*Reliancesolely on NDViproducts from theAMRRimagery nel Microwave Radiometer (smmRt)data from the -brzooody biomass mapping is questionable-It has been mirowave portion of the spectum should be con- shown that thermal infrared data, also available sidered in future studies. fr-om the .AvHRRprovides ad ditional infonmation *Year-to-year variations in. vegetation cover, photos- thaitcanbeused to rf ineland covermaps produced ynthetic activity,and the resultant ,mivvIresponseshould * using oI products. it is particularly usefl for beconsidered. These were not considered in the pre- identifying andmappinglandcoverdisturbance. In sent study, and the present maps are only a situa- addition, the applicability of Scanning Multichan- tional overview of the woody biomass resource for 44 EstimatingWoody Bionmss in Sub-SalharanAfrica

They are subject to change caused by human inter- Support Programxs vention and climatic variation. Significant im- provement to the maps of land cover, growing * Earlyinvolvementoflocal,regional,andnational stock, and sustainable yield would occur with use organizations of the complete AvHRRdata set spanning 1981 to * Technical assistance and support in staffing and 1988. the supply of necessary hardware, software, and Medium-term monitoritg of the woody biomassre- training programs in developing countries. soturce, for example, spanning a 5-to-10-yearperiod, requires(a) a highi-qualitybaseline data set, (b) data of Links withiStudies of tlteDemnand Side tie appropriatespatial resolution to detectchanges, and (c) a robust metihodology.We doubt that AVHRRdata * Coordination with studies of woodfuel demand of 8-kilometer spatial resolution would allow rec- in the same land cover classes ognition of changes in land cover class caused by * Supporting studies of competing end uses of human activity that spans periods briefer than a wood. decade. The NDviis very sensitive to rainfall and soil moisture variations. It is apparent from research The following areas in Sub-Saharan Africa should already undertaken that, utilizing a phenological receive high priority as areas in which to conduct the strategy for mapping at this scale, changes in land research just outlined: cover classes caused by such variations probably will mask changes caused by human activity. 7he Sudanian Woodlandsof the Sudano-Sahelianzone. The work reported here dearly identifies and maps Other areas require further research three belts of Sudanian Woodland that are differen- tiated by the length of their dry seasons and by their Improvementof the Data Base moisture regimes. These belts stretch from Senegal to Sudan, covering 13 million square kilometers, - Harmonization of assessment techniques for and are a principal source of woodfueL This area woodybiomass currently is experiencing a dual threat to the fuel- = Ground sampling that includes destructive sam- wood supply. First, people are migrating north- pling to establish the relation between measurable ward into these woodlands from the environmen- parameters and the weight of woody biomass tally stressed areas of the SaheL Second, the large - Preservation of permanent plots for long-term population centers to the south, along the West monitoring to determine annual growth incre- African coast, are increasingly relying on woodfuel ment and sustainable yield from these woodlands to meet their domestic en- - Assessment thatincludes the herbaceous compo- ergy demands. nent of biomass The main factors to be covered by such work are Study to relate the age structure of vegetation to (a) mapping of the land cover classes within the its productivity. Sudano-Sahelian zone at a fimer spatial resolution and (b) a greatly enhanced data base on the woodv TechnicalImprovement biomass growing stock and sustainable yield. Such work could be accomplished by using Landsat im- * Useofremotelysensedimageryhavingappropri- agery for interpretation of land cover and by estab- ately finer spatial resolution lishing a local network of biomass assessments Inclusion of continuousremotely sensed data, re- within the woodlands. corded during a span of several contiguous years * The dry-zonecorridor of southernand EastAfrica. This as opposed to a single year, to produce land cover dii -r-. belt, typified by arid and semiarid vegeta- maps that are more independent of year-to-year tion and farmnng systems, extends from Ethiopia climatic varations and Somaliasouthward througheast-central Africa * Support of satellite remotely sensed imagery to Botswana and Zimbabwe. The zone comprises with other fom-s of assessment, such as aerial several areas of ecological stress resulting from photography and ground verification scant rainfall and strongly seasonal moisture re- * Integrated use of three powerful tools: assess- gimes. This area is important for woodfuel supply ments of land cover and woody biomass, envi- because of the great rural population density and ronmental data bases for climate, demography, large urban centers. Woodfuel supplies have been and other factors such as soils, and geographical depleted by clear felling for agriculture. Several information systems. local studies of good quality provide benchmark References

Every effort has been made to facilitate access to the AustralasicnRemote Sensing Conferece (6th: 1992: documents listed here. Some documents, however, Wellington,New Zealand),2-6 November, Vol. 1, lack full bibliographic information because it was un- 1.140-1.149. available; also, some documents ae of limited circula- Brown, S., and A. E. Lugo. 1984."Biomass of Tropical ton The word "processed" descrbes informally re- ForestsANewEstimateBasedonForestVolumes." produced works that may not be commonly available Sdence223:1290-93. drough libaries. Catnot, R. 1978."The Forest Ecosystemsof Gabon:An Overview." lInvUm (JrdtedNationsEducational Andeke Lengui, M. A. 1987. Formulationdu projet ScientificandCulturalOrganization), TropicalForest amdnagemt et reboisementfJrestiersAbhts multiples. Ecosystems.Paris uNO. iME f 85/009 Dcumentde terrainNo. 22Niamey, Chidumayo, E.N. 1987."SpeciesStructureinZambian Niger Ministbre de 1'Hydraulique et de l'Environ- MiomboWoodland-" Journalof TropicalEcology 3(2): ment. FAo. 109-18 Baines, A. C. 1980. "Sierra Leone: Assistance to For- CLristiansen, J. H 1978. 'Biomass and Primary Pro- estry Development." Freetwn. Processed. ductivity of Rhizpho Apiculea in a Mangrove in Barber, Dennis R- 1992."The AppLcation of Change SouftermT and. AquaticBotany4:43-5 Detction Techiques to Rangeland Monitormg in Climent, J. 1982. "Estimation des volumes et de la South Australia." Proceengs, Avstrasian Remte productivit6 des formations mixtes foresti&res et .SensingConference (6W 1992: Wellington, NewoZea- gRinues tropicales v ue Bois et Forts des land),24 November, VoL1, 1.413-1.416. Trpiques, 198(4):35-58. Bartholomew,W. V.,J. Meyer, and -LLandelot 1953. Cline-Cole,Regiald, J. A. Falola, IL A. C. Main, Mi- -Minerdl Nurient Immobilization Under Forest chael E Montimoe Janet E. Nichol and Frank D. and Grass FalUowin the Yangambi (Belgian Congo) 0. O`Reilly.1987. Woodfu in Kano.Department of Region." Sie Scientifique57 lnstitut National. GeogVaphy,Bayero University, Kano, Nigeria. Final Bianhi, I-L 1986.Assistace, au dEveloppen sntfiwstier, report oftherural energy researchprojectsubmitted Guinec Bissau; Planificationforesti?re. Tc;a'/s to the UN. UnniyDeparnert StudiesDivision. 4506(A).Document de terrain. Rome: FO. Cracknell,Arthur P., and Ladson D. Hayes. 1991.In- Black,R. 1989. "Africa's Refugee Crisis." Geognphical troduction-to Remote Sensing. London: Taylor and Magezine61(1)12-1& Francis. Bonkoungou, L, L. Bortoli, and J. M. Oudba. 1988. Danaher, T. J.- J. 0. Cart, D. Bok A. Peacock, "Note an Burkina Faso Ecosystems: Woody and and G. S. Dudgeon. 1992. "Broad-ScaleVegetation IHerbaceous Vegetation Characteristics of a Pro- Mapping Using NOAvRR Imagery.- Proceedings, tectedFallowin DegradedSudaian Zone.lInstitut' Australain Remofe Sensing Cifnere (Wth 1992: de Recherche en Biologie et Ecologie Tropicale Wedlington,New Zaland), 2-6 November, VoL 3, (ier) Ouagadougou, Burlina Faso. Processed. 3.128-3.137. Brook, KD.,J. 0. Carter,T. J.Danaher,G. NEMdxCon, Daus, Steven J., Mamane Guero, and Lawally Ada. N. R Flood, and A. Peacock. 1992. "The Use of 1986."A Remote-Sensing-AidedInventory of Fuel- SpatialModellingand RemoteSensingforMonitor- wood Volumes in the Sahel Region of West Aficac ing and Forecasting of Drought-Related Land A Case Study of Five Urban Zones in the Republic Degradation Events in Queensland." Proceedings, of Niger." Paper presented at Symposium on Re-

46 References

Every effort has been made to facilitate access to the Australasian Remote Sensing Conference(6th: 1992: documents listed here. Some documents, however, Wellington, New Zealand), 2-6 November, Vol. 1, lack full bibliographic infornation because it was un- 1.140-1.149. available; also, some documents are of limited circula- Brown, S., and A. E. Lugo. 1984. "Biomass of Tropical tion. The word "processed" describes informally re- Forests ANew EstimateBased onForestVolumes." produced works that may not be commonly available Science223:1290-93. through libraries. Catinot, R. 1978."The Forest Ecosystems of Gabon: An Overview." InuNEsco(United Nations Educational, Andeke Lengui, M. A. 1987. Formulation du projet Scientificand Cultural Organization), TropicalForest ambtagementet reboisementforestiersa buts multiples. Ecosystems.Paris: uNEsco. ivtNm/ 85/009 Document de terrain No. 2. Niamey, Chidumayo, E. N. 1987."Species Structure inZambian Niger Minist&re de 1'Hydraulique et de l'Environ- MiomboWoodland." Journalof TropicalEcology 3(2): ment. FAO. 109-18. Baines, A. C. 1980. "Sierra Leone: Assistance to For- Christiansen, J. H 1978. "Biomass and Primary Pro- estry Development." Freetown. Processed. ductivity of Rhizopho7aApiculatea in a Mangrove in Barber, Dennis R. 1992. "The Application of Change Southem Thailand." Aquatic Botany4:43-52. Detection Tecbniques to Rangeland Monitoring in Clenent, J. 1982. "Estimation des volumes et de la South Australia." Proceedings,Australasian Remote productivite des formations mixtes forestieres et Sensing Conference(6th: 1992: Wellington,New Zea- gramnmennes tropicales." Revue Bois et Forets des land), 2-6 November, Vol. 1, 1A13-1.416. Tropiques,198(4):35-58. Bartholomew, W. V., J. Meyer, and IL Landelot. 1953. Cline-Cole, Reginald, J. A. Falola, IH A. C. Main, Mi- "Mineral Nutrient Immobilization Under Forest chael E. Montimore, Janet E. Nichol, and Frank D. and Grass Fallow in the Yangambi (Belgian Congo) 0. O'Reilly. 1987. Woodfuelin Kano. Department of Region." S&rieScientifique 57 Institut National. Geography, Bayero University, Kano, Nigeria- Final Bianchi, H. 1986. Assistanceau d6veloppementforestier, reportoftheruralmergyresearchprojectsubmiitted Guinee Bissau; Planification forestiere. TCP/GEIS/ to the U.N. University Department, Studies Division. 4506(A). Document de terrain. Rome: FAO. Cracknell, Artiur P., and Ladson D. Hayes, 1991.In- Black, R. 1989. "Africa's Refugee Crisis." Geographical troduction to Remote Sensing. London: Taylor and Magazine61(1):12-1& Francis. Bonkoungau, L, L. Bortoli, and J. M Oudba. 1988. Danaher, T. J.,' J. Carter, K D. Brook A. Peacock, "Note on Burkina Faso Ecosystems: Woody and and G. S. Dudgeon. 1992. "Broad-Scale Vegetation Herbaceous Vegetation Characteristics of a Pro- Mapping Using NoAA-AvHRR Imagery." Proceedings, tectedFallowinDegradedSudanianZone."Institut Austnlasian Remote Sensing Conference(6th: 1992: de Recherche en Biologie et Ecologie Tropicale Wellington,New Zealand), 2-6 November, VoL 3, (=ET), Ouagadougou, Burkina Faso. Processed. 3.128-3.137. Brook K D.,J. 0. Carter,T. J.Danaher, G. lvi McKeon, Daus, Steven J., Mamane Guero, and Lawally Ada. N. R. Flood, and A. Peacock. 1992. "The Use of 1986. "A Remote-Sensing-Aided Inventory of Fuel- SpatialModelling and Remote SensingforMonitor- wood Volumes in the Sahel Region of West Africa: ing and Forecasting of Drought-Related Land A Case Study of Five Urban Zones in the Republic Degradation Events in Queensland." Proceedings, of Niger." Paper presented at Symposium on Re-

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Regional Distribution of Land Cover Classes

Part II of this book examines the regional distribution of In eachregion, we describe only large classes of land landcoverdasses(figure3-5).Broadecological,environ- cover (those having an areal extent greater than 1 mental, and economic criteria defined our six regions: percent of the region), with the exception of smaller areas that are important to an individual country. * West African Sahel (Mauritania, Senegal the Gam- We present each class in relation to its geographical bia, Mali, Burkina Faso, Niger, and Chad) distribution within the region, describe the main ele- * West African coast (Guinea-Bissau, Guinea, Sierra ments in the natural vegetation and land use, and Leone, Liberia, C6te d'Ivoire, Ghana, Togo, Benin, address the current and future fuelwood resource, as and Nigeria) appropriate. * The Hom of Africa (Sudan, Ethiopia, Djibouti and For some important classes in each region, NDVI * Somalia) profiles are plotted to afford an impression of how * EastAfrica(Uganda,Burundi,Rwanda,Kenya,and land cover can be differentiated using the methods Tanzania) described in Chapter 3. At the conclusion of each * Central Africa (Cameroon, Central African Republic, regional chapter are tables that provide national data mmnlandEquatorialGuinea,Gabor,Congo,andZai.e) on the area, growing stock, and sustainable yield for * Southern Africa (Angola, Zambia, Malawi, Mozam- each land cover class. References are also supplied. At bique, Zimbabwe, Nanibia, Botswana,South Africa, the end of Part 11are the four regional maps depicting Swaziland, and Lesotho). the land cover classes. -~

The West African Sahel Richard W. Critchley

This chapter presents a detailed description of the exist, consisting of the extensive rooting systems of most importantlandcoverclassesinthisregion.Help- drought-resistant geophytic plants. This, of course, ful figures in other chapters include figure 3-1 (cloud cannot be considered a sustainable fuel resource. cover); figures 3-2, 3-3, and 3-4 (Now sununary land Other species are ephemerals, surviving by the pro- cover profiles); figure 3-5 (regional summary map of duction of seed during favorable periods. Rainfall in land cover classes); figures 7-1 and 7-2 (continental the more northern areas of the region may be ex- maps of growing stock and sustainable yield); and the tremely rare, as little as one event in 10 years, and "Regional Land Cover Class Map of West Africa" at may occur as brief rainfall events of 10 to 30 milli- the end of this volume. -meters. Helpful tables in other chapters include table 3-2 Following a rainfall, a brief explosion of vegetative (land cover classes); table 4-1 (data and sources for activity forms a herbaceous carpet, creating a system growing stock and sustainable yield); and table 6-1 referred to as acheb.The plants that emerge are mostly (West African Sahel estimated woody biomass by tropical, although overlap exists with more Mediter- summary class). ranean species in areas of greater relief, such as the Air Mountains in MNgerand the ribesti Plateau in Chad. Class 0-Desert Herbaceous species also are present, such as the his- sock-forming grass Stipagrostispungens and the grass Within the region that we designate West African Panicumturgidum, which responds to water availabil- Sahel in this study, the dominant land cover class in ity by rapid vegetative growth from dormant buds at relation to surface area is desert, about 50 percent. The ground level, providing an important food for ante- countries of Mauritania, Mali, Niger, and Chad extend lope. The annual grass Coelachyrumcompressa can es- well into the northern Sahara. In these areas, where tablish itself on the banks of wadis, and the perennial precipitation is scant and evaporation is rapid, the stolon-forming grass, Eleusine compressa,also repre- flora is restricted to more favorable locations where sents the tropical desert flora (Gillet 1986). Aristida groundwater may be available, such as dried-up river pungens,A longflora, Cornulacamonocantha, Cymbopo- beds or wadis. gon monocantha,Eragrostis sp., Stipagrostis uniplumis, Rainfall in the western half of the Sahel region has and Tribudussp. also are described in these areas and been less than average in every rainfall season since farther south. 1968 (no 1989). Because much of the region is mar- The southernmost edge of the class approximately ginal for agriculture, an extended reduction in precip- coincides with the 20-millimeter isohyet. In this area, itation is likely to be disastrous. The contribution of or in depressions farther north where runoff may aug- this dass to the regional growing stock of woody ment the available water supply, woody species do biomass obviously is negligible, although locally it occur. The commonest is Acacia tortilis ss. raddiana, may be significant to nomadic people in the southern which has a restricted but uniform distribution. Lepta- portion of the area. denia pyrotechnicais restricted to dunes and Balanites The vegetation is not obvious for most of the year, aegyptiacaand Commiphoraafricana occur locally in the although significant below-ground biomass may low peneplains (Le Hou&ou 1980).

53 54 EstimatingWoody Biolass in Sub-SalmrenAfrica

The south Saharan plateaus of Ar (Niger),Adrar Figure 8-2. NDVI Profile, Hydromorphic Grassland des Iforas (Mali),and Ennedi (Chad)provide areas of (Class12) increased runoff and slightlygreater rainfalls.They are characterized by the SemidesertWooded Grass- 0.6- land Vegetation (Class 21), and in general, woody -ZChmd biomassgradually increasesas total precipitation,ire- os5 quency, and regularity increase toward the south of 0.4- the zone. Because of the supervised classificationtechnique 0.3- used to map land cover (Chapter 3), some small par- cels of land in Niger appear to be Class 0, but are surrounded by Class 21. These are believed to repre- sent degraded areas. The causes of this degradation are.considered to be of two kinds. The first cause is o, cyclicclimatic vanration, leading to an increasein arid- Jan reb Mar Apr May Jnn Jul Aug Sp Oct Nov Dec ity spanning a period of years. In such areas, the vegetation would be expectedto recover in years of greater rainfalL The second cause is believed to be Class 21-Semidesert Wooded Grassland anthropogenic activity,and such areas could return to greater production levels with appropriate land The SemidesertWooded Grasslandclass forms a rela- management tivelynarrow belt, at itsbroadest about 400kilometers, nnig fromMauritania in the west through central Class 12-Hydromorphic Grassland Mali, northern Burkina Paso,southwestem and cen- tral Niger, centralChad, and extending into East Af- Thisclass has a very restricteddistributionin the West rica. It covers about 19 percent of the surface of the African Sahel, covering less than 1 percent of the re- West African Sahel region. A.more limited distribu- gion. Its contributionto the regionalwoody biomass tion occurs north and south of this zone within the growing -stock and sustainable yield is negligible Desert (Class 0) to the north and the Sahel-Sudanian (table 6-1). . AcaciaWooded Bushland (Class 44) farther south The The biomass activity produces a. relatively small Semidesert Wooded Grassland class corresponds NDvi response (for example,in Chad, figure 8-1)but largelyto mapping unit 54aof White(1983).IThe more with a marked seasonality.It is small in March and northerlyextensionsare associatedwiththemassifs of April at 0.35, but smallest in September at 0.20. Peaks Adrar des Iforas (Mali),Air (Niger),and Ennedi (Chad), in production are indicated in Decemberand January but the floral constitution of these areas is different with values of 0.55, somewhat later than the peak due to the inclusionof Saharandesert species. precipitationof the wetseason (uly and August).This Rainfallintheregionis about250millimeters a year, lag relates to the drying out of waterloggedsoils. with a marked seasonality.Rainfall peaks in July and Hydromorphic Grassland occurs as small patches August and coincideswith summer temperatures to witiin the Dry Sudanian Woodland (Class62) in the produce warmth and humidity that can cause rapid westem and southeastern portions of Mali and to a and vigorous plant growth. The monthlyNmm curves lesser extent in eastern Senegal and in Chad, south- show a marked seasonality,with peak values of 0.44 west of N'Damena. Its distribution in Mali is associ- in September-in response to the increased rainfall, ated with the Manding Plateau,and similarly with fallingto 0.10in May (figure8-2). The northern limit minor plateaus in SenegaLIn Chacfit represents a of the class coincidesapproximately with rainfallsof grassland vegetation formed on Quaternary clays in 100 to 150 millimetersa year, whereas the southern areas susceptibleto flooding.White (1983)considers limit coincideswith the 500-millimeterisohyet We this to be the most widespread kind of edaphicgrass- estimatethe class to contributeabout 6 percent of the land, similar to that forming on seasonallyor perma- growing stock and 13 percent of the sustainableyield nently waterloggedsoils in the upper Nile Basin.More in the region. extensiveareas occur in Sudan and northern Nigeria The vegetation consistsof grasslandwith a crown and complete an east-to-westpattem wiffiinClas 62, cover of less than 10 percent woody species. In the Dry Sudanian Woodland. northem extreme of the zone, annual plants are asso- For a more completedescription, please refer to the ciatedwith wadis or plateau regions,but are typically regionalreports for the West Africancoast (Chapter9) tropicalrather than Mediterraneanin origin. Annual and Hom of Africa(Chapter 10). grassessuch as Codlachyrumbremifolium and perennial - W-TheWetAoran She 55

Figure 8.2. NDVI Profile, Semidesert Wooded A. tortilis attaining 5 meters height, with total woody Grassland (Class 21) biomass rarely exceeding 3 percent of the above- pgound biomass. This species also provides shade 0.6- within which herbaceous vegetationmay thrive and - 21 Mauritania persist long after the and of the dry season. Also "S- - - . describedamong the more important woody species Oh - _ reported by White(1983) are Acacialacta, A. ehrenbergi- /anat(flw),Balanitesaegaptiaca, Bosciasenegalensis, Cam- 0.3-ffi / mipboraafricana, and Laptadeniapyroteclrn ea. Anogeissusleiocarpus, an important fuelwood tree, 0.2- also increases to the south in this class. The size to

o.l- > - - .whichsemidesert treesbeing grow stuntedvaries, those and inattaining the northem full stature Sahel o- 4only - with increasedrainfall in the south of the region. ionXFeb MAr AprMay ion Jul Augsep dat NoC ; Calligonumcomosum, a typical Saharan shrub, often is associatedwith Panicumturgidum in areas where rain- fall is locallygreater. species such as Eleusinecompressa are cited by Gillet Humanpopulation density is low in the region but (1986)as representingthe basic Sahelianflora. generallyincreases along a nort-south transect.The WhererainfallexceedslOOmillimetersayear.andis great drought of 1968-73 saw extensivemovement predictable, a more permanent steppelike vegetation southward (Granier 1980), intensifying the pressure develops.Indeed, on a north-southgradient, a general on a system that has a low carrying capacity. In.this imcrease occursin the proportion of trees. This more region,the most characteristicactivity is pastoralism, southerly region coincideswith the second Sahelian associated with seasonal movements of herds and zone described by: Boudet (1972).Local conditions flocks. vary and considerabledifferences exist in the propor- tionof woody species, but White's description(1983) Class 44-Sahel-Sudanian Acacia Wooded of bushes and small bushy trees within grassland Bushland seems appropriate, with more favorableareas devel- oping sufficient woody biomass to be described as. This classlies south of the SemidesertWooded Grass- bush. land (Class 21) and forms a parallel belt of similar The species represented in the herbaceous layer width across the region, extending into East Africa, vary considerably from east to west, with local varia- with significant representation in all nations in the tions related to the proportion of sand and clay within Sahel except the Gambia. In Mauritania, only the areas the soil. Generally, however, tussock-forming grasses along the Senegal River Valley, the escarpments of gradually give way to perennial, steppelilke species 'Assiba and Tagant, the Massif of Afolle, and the southward along a north-south transect. Annual Hodh Basin in the southeast are included. All other grasses such as Aristida mutabilis,A. adscensionis,A. countries in the West African Sahel include significant stipoides,Cenchrus biflorus (cram-ram), Scdoenefeldia areas that add to 17 percent of the surface of the region. grcilis, and Thzgusracemnosus are widespread and typ The class is associatedwith greaterrainfall than Class ical of the northern Sahelian semidesert, whereas 21, with annual precipitation between 250 and 500 perennial grasses such as A. mutabilisand Panicum millimeters occurring largely-in July and August turgidum extend quite far south. Regionally, this class is important for woody biomass, On unstable soil systems such as dunes, gasses contributing an estimated 5 percent of the growing such as Stipagrostispungens are more common; such stock and 31 percent of the sustainable yield (131 species also are associated with lesser rainfall. The million tonnes and 30.7 million tornes, respectively). instability of tall dunes farther south favors the pres- The Nxvi phenologies of this type of land cover ence of Aristida sieberanaand Panicum turgidumand exhiibit the greatest value dunng September (figure their distribution is increased at the expense of woody 8-3).The greater NDviperiod has a duration of 2 to 3 species by processes that encourage desertification. months, and throughout the rest of the year.Nxvxval- Of the woody biomass component, the Acaa genus ues are approximately 0.08. The growing season is is representedbyanumberof species. Widespread are longer in the west, and there herbaceous. vegetation Acaciatortilis ss. rddiana, A. senegal,A. seyal, and, in persists through a large part of the year. the more southerly limits of the zone, A. nilotica In The herbaceous layer consists mainly -of annual. the northiem part of the region, White (1983)reports grasses, including species represented farther north 56 Es1tinialg WoodyBiomtass in Sub-Sclarant Africa

Figure 8-3. NDVIProfiles, Sahel-Sudanian Mcacia A case study of two traditional systems of consump Wooded Bushland (Class 44) tion in the Sahel-Sudanian zone of Burkina Faso (MArz 1986) suggests that 75 percent of all wood collected is 0.6- for fuel and that farmers very carefully select different - 44Sciegl tree species for different uses. The area required to 0,5- 44Nigr bUpply the wood demand of each person is 1.4 to 2.8 OA- hectares from a system producing 0.16 to 0.48 tonne a hectare. In areas seen during field visits in December 0.3- 1988, a great intensity of land use was noted for many kilometers around both Dakar in Senegal and Bamako 0.2- \ / / - \in Mali, with agricultural plots and fallows in regular o1 l - - - '-pattems,serving both the cities and numerous villages. -i -In recent years, in Burkina Faso in particular, large 0I , M M J , A ,p N, numbers of people have moved from the north to the Jn rcb Mar Apr MayJun Jul AugScp Oct NovDee southwest in response to population increase. The associated agricultural activity has led to degradation of the environment and the effect is apparent on the such as Aristida stipoides,A. mutabilis, Cenchnrsbiflones land cover class maps, where areas of Semidesert (cram-cram), Chlorisprieurii, and Schoenoeldiagracilis. Wooded Grassland are surrounded by Sahel-Sudan- Perennial grass spedes such as Andropagon gayanus ian AcaciaWooded Bushland. Areas of wooded bush- occur farther south. The ground vegetation is more land also extend farther south into the Dry Sudanian persistent than in Class 21 to the north and survives Woodland (Class 62). almost to the end of the dry season, attaining heights A recent study of the fuelwood resource in Niger greater than a meter. (Daus, Guero, and Ada 1986) indicates varying de- Of the woody species, Acacia tortifis ss. mddiana is grees of vegetation degradation associated with areas the most common in the north of the zone. According of greatpopulationdensityin the south and southwest to White (1983), it varies in form throughout the re- of the country. In study areas of 200 kilometers diam- gion, being short and bushier farther north with a eter aroundfive urban zones, the greatest degradation maximum height of 4 meters, whereas in the south it occurred around Tahoua, where the ratio of woody is a bushy tree of up to 8 meters. Regional descriptions biomass to surface area is smallest This juxtapos: ion identify differences in species com.position across the of two classes, the class associated with lesser woody Sahel. Of widespread occurrence are Acaciasenegal, A. biomass occurring against a background of greater seyal, members of the Combretaceae, especially Com- woody biomass, suggests that extensive vegetation bretum glutinosum in the Sahelian zone of northern landcoverdegradationcanbe mappedfrom8-kilome- Burlina Faso, and Ziziphus mauitiania. ter-resolution AVHRRNDVIimagery. Adansoniadigitata (baobab) is locally abundant, par- ticularly around villages or on more saline soils. Buty- Class 62-Dry Sudanian Woodland rospermumspp. and Parkia biglobosa,more Sudanuan species, are particularly important as fuelwood in This class lies south of the Sahel-Sudanian Acacia Burkina Paso. Bush species include Acacia mellfrra, Wooded Bushland (Class 44), form-tinga narrow belt Commiphoraafricanm, and Euphorbiabalsamifmra. . through southern Senegal, the Gambia, southern and Asignificantdifferenceexistsbetweenvegetationin western Mali, southern and western Burkina Faso, the the north of the region, where the mnainhuman land southerrunost area of Niger, and southern Chad. Al- use is nomadic and pastoral, and that in the south, though forming quite extensive areas-about 10 per- where agricultural activity is more sedentary. This is cent of the West African Sahel-it is penetrated by related largely to the ability to grow crops such as nmanyother vegetation classes from farther north and millet in the south. In Niger, this difference is associ- south, forming complex mosaics in western Mali and ated with the 350-millimeter isohyet It may also be Chad in particular. related to seasonal transhumance in response to the This class corresponds to the Sudanian Undifferen- growth of vegetation in the wet season (Peyre de tiated Woodland mapping unit 29a of White (1983) Fabregues 1980).Granier (1980)describes how people and lies within the Sudanian regional center of ende- in Mali use indigenous woody and herbaceous spe- mism (M). Inmany instances, Whiteconsidersthe-area cies, andshowsthe intimaterelationshipbetweenpeo- to be a product of agriculture, consisting of land under ple and plants that must be borne in mind when cultivation orbush fallow, the original vegetation pos- considering the potential fuelwood resource in this sibly having been dry forest Certainly in Senegal, region. - - Mali, and Burlina Faso it coincides with areas of dense Tie West African Sahel 57

permnent settlement. RegionaLly,57 percent of the short-trunked, thick-barked, fire-resistant species, growing stock and 41 percent of the sustainableyield with thin-barked species surviving in areas that es- are estimated to come from this class (1,439million cape regular burning or agriculture where they form tonnes and 41.5 million tonnes,respectively). areas of closedwoodland. Farther south, more water- The area is associatedwith annual rainfallsof 750to demandingspecies are in evidence. 1,250millimeters with a dry season of 7 to 9 months. Butyrospermumparkii,which traditionallymarks the In areas of greater rainfall,such as lower Casamance start of the Sudanian zone, and Parkiabiglobosa are in Senegal,the region mergeswith the Cultivationand more common,particularly around villages.Both spe- Forest RegrowthMosaic (Class 73). Phenology curves cies are used by the local population. They probably for sites in BurkinaFaso and Senegal(figure 84) show represent the remnants of dry forestcover eliminated increasesin NDVIbeginning in June or July,peaking in by human activity. Butyrospermumspp. also exhibit August and Septemberat 0.48in the BurkinaFaso site good regenerationfrom a root crown and many of the before fallingbacktobaseline values of approxumately Combretaceaeshowcryptogeal germination,enabling 0.10.This contrasts with an earlier start to the growing them to recoverfrom fire damage. season for the vegetation in Classes 64 and 65, for Other tree species typicallypresent around villages which growth begins in March or April. includeAcacia albi/a, Adansonia digitata (baobab), Bom- The vegetation is typically open woodland with baxcostatum, Borassusaethiopum, Man gifera indica, and mainly deciduous trees, 15 to 25 meters in height, with Tamarindusindica. Khayaseneglensis, Parkiabiglobosa, a herbaceous carpet dominated by grasses, although and Pferocarpuserinaceus are reported as forming dry shrubs, bushes, and climbers are present The peren- woodland in Senegal (Ndidye1983). Bosweilia dalzieli, nial herbs include Andropogongmjanus on sandy soils; Commiphoraspp., and Ziziphusspp. also are present Cymbopogongiganteus, Ctenium newtonii, and Hyparr- Areas that Steentoft (1988) descnibes as "savanna re- heniadissoluta on wetter soils; and Laudetiasimplex on growth" are vegetated by Adansonia digitata, Acacia slopes or rocky outcrops. Among the annual grasses albida, Bajanitesaegyptiaca, Butyrospernum sp., Ceiba are Andropogonpseudopricus, Eragrostistremnula, Pen- sp., and Tamarindussp. nisetum pedicellatum, and Utenium elegans, the latter Bush and shrub species include Hyphaenethebaica, a considered by Steentoft (1988)to be an indicator of palm used for building,together with members of the disturbed ground. During the dry season, the herba- Combretaceae, Rubiaceae, and Euphorbiaceae. In ceouslayer becomeshighly combustible,and frequent moisterregions of Senegal such as river valleys,Borassus fires bum when the harmattan blows. The merger flbdlifr (rhun palm) and Oxytenantffraabyss/nica (a with the Cultivation and Forest Regrowth Mosaic bamboo)occur (Ndiaye1983). Gallery forests including (Class 73) in southem Senegal is marked by the ap- Colalaurfolioand Mitragynainermis exist in Niger(Peyre pearance of herbaceousspecies such as Danielliaoliveri de Fabregues1980). and Ejythrophteurn aineense. The woody layer contains a significantnumber of Class 64-Sudanian Woodland thomy species typical.of the Sahel-SudanianAcacia Wooded Bushland (Class44) to the north. Largenum- This classoccupies 3 percent of the WestAfricanSahel bers of Combretaceae,including Anogeissusleiocarpus and occurs in southeastern Senegal, western and and Combretumglutinosurn, can form distinct wood- southwestem Mali southwestern Burkina Faso, and lands, and Acaciaspp. are common. Many trees are southerrmost Chad. It corresponds approximnatelyto mapping zone Ila of White (1983) as a mosaic of Figure 8-4. NDVIProfiles, Sudanian Woodlands lowland rain forest and secondary grassland, lying in (Classes 62,64, and 65) the center of the Sudanian regional center of ende- misimIt incorporatesspecies from the drier northern 0.6- part of the Sudanianregion, includingAcacia spp. and ,-* - members- of the Combretaceae,together with species o.s- -,, ;, more typical of the humid southern parts such as 0.4- , " Kh-@:,1aya senegalensis and Lophira lanceolata,both Sudan- - , A.ian endemic species. >03- ,, :---- 1 j -*Class 64 is intimately associatedin the south of the z : ,- , ' Av - >, region with Dry Sudanian Woodland (Class 62), and 0.2- --- ' -,,e Xl- 2 S is considered in some areas to be a degraded form of 62 BurldnaFaso drywoodland.Itmayrepresentparcelsof groundthat 0.1- ~ /- ---- 64 BurkdnaFaso - are less accessible or are forest reserves. (The imagery 0------Chad 65 appears to show areas of Sudanian woodland coincid- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dc ing with "foras dassees" around Bobo Dioulasso in

:.0 . .. -, . - . , 58 EstimatingWoody Biomassin Sub-SaI:aronAfrica westemrn3urkinaFaso).lntheregion,SudanianWood- The class is more fully and typically described in land is estimated to be 15 percent of the growing stock Chapter 9 on the coastal West Africanregion. and 6.5 percent of the sustainable yield (378million tonnes and 6.5 million tonnes, respectively). Class 65-Moist Sudanian Woodland Climatically,this zone has a precipitationof at least 1,100millimeters a year with a dry season of 6 to 7 Class65 has a very limiteddistribution, only 1 percent months from Octoberto May. Monthlyrainfall values of the land area in the West African Sahel region, during the wet season of July and August are 250 to occurring to a significantextent only in southeastem 350 millimeters, with mean daily temperatures of Chad, with isolated small pockets in Burkina Faso. It about 28-300C. This vegetation is clearly the northem correspondsto mapping unit 27 of White (1983)or the limit of the coastalWestAfricanregion.The factor that northern Guinea savanna of Steentoft(1988). limits the growth of woody species is the length of the Climatically,the region is similar to that in which dry season, and characteristicallythe trees are decid- SudanianWoodland (Class 64) develops,having a dry uous. Tie canopy is seasonally open and, in combina- season of 5 to 7 months. The vegetation is similar in tion with the relativelywide spacing of the trees, light structure to that class, but is dominated by Burkea is able to penetrate, allowing tussocky grasses such africana,Daniellia sp., Erythrophleumafricanum, Isober- as Andropogon gayanus, Hyparrheniacyanescens, and liniadoka, and Lophiralanceolata. It represents the most Schdzachyriumsanguineum to attainheights greaterthan northerly extensionof a zone of vegetation occurring 1.5 meters. in the coastal West African region and spreading Granier (1980),in describing the biogeography of eastward to Cameroon,Central AfricanRepublic, and Mali,classifies-this area as partof the Sudano-Guinean Sudan. domain with a savanna-woodland mosaic, subject to Where it occurs in the Sahel, this class forms a regular fires and with gallery forest in the valleys. mosaic with Sudanian Woodland (Class 64) and Dry Ts&tseis common and this may explainsomewhat the Sudanian Woodland (Class 62). The contribution to lesser exploitation of this area, compared to more the regionalgrowing stockis significant,estimated as degraded examplesof SudanianWoodland (Class64). 4 percent of the grDwingstock and 1.7 percent of the Characteristicspecies are Isoberliniadoka, a fire-resis- sustainableyield (100million tonnes and 1.7 million. tant species, Afzelia africana,Danillia oliven, Erythro- tonnes,respectively). phleumguineense,and U4pacasomon. Phenologies appear to be similar to those of Ndiaye (1983)similarly identifiesthe equivalentre- Classes 62 and 64, but with a maximum vN value gion in southem Senegalwith a number of dominant of 055 occurring earlier in the year in May and June woody species,including senealensisgaaya and Lophim and remainingat approximately0.45 until September lanceolaatas well as ParkaMbiglobosa and Pterospus (figure 8-4). erntaceus.In valleys,thebamboo Oxytenantheraabyssinica Moist Sudanian Woodland is an open woodland and the rhun palm Bomssusflabeldfer occur. The rhun savanna, considered by some to be a reduced form of. palmalsooccursasplantationsinsouthwestemBurkina miombobecause fewer species are present and trees Faso. Sanford and Ischei (1986),in describing"Guinea rarely attain heights greaterthan 15meters. Typically, savanna," identify Danidl1aoliveri, Isoberliniadoka, r.1 it includes Monotes kerstingii on dry eroded slopes tonentosa,and Parkiacappertina as importantspecies, (Steentoft1988). In the northemmost part of the area, but in the more northern areas the Isoberliniagenus is commonspecisareCussonahbarten,Enadafi7ana,lsober- consideredby Whiteto be resticted to smallpodcets on limnatfosa, Lannm mncrocarpa,Terminalif avicennioides, rockyhills - and Xmn ameaa, but taces of Sahelianvegetation The term "derived savanna" is used for large parts occur in the form-of Aadt spp. (particulalyA albida), of this area, but the effect of human activity is much Burkeaaficana, and ViBostigmathonningi. lessthan intheneighboringClass62.Agradientof tree In areas where the woody biomass is regenerating, cover probably exists,with the cover diminishingas speciessuch as Isoberliniasp., Piliostigmasp., and Ter- one moves from Sudanian Woodland (Class 64) into minaliaavicennioides exhibit the ability to regrow from areas more properly described as Dry Sudanian underground suckers and hence have an enhanced Woodland (Class62). ability to withstand fire. The appearance of Isoberlinia The phenological curves (figure 8-4) indicate that is considered to correspond with the 1,000-millimeter the maximum No value of 0.43occurs in August and isohyeLAn understoxyof climbers and shrubs may be September with the smallest value of 0.13 in January, present, and a herbaceous carpet of perennial grasses February, and March. These indicate the distinct sea- occurs, including Andropogon spp., Eragrostis spp., sonality of the vegetatiorL Schizaclyriumspp., and Pennisetumspp. This class in the Sahel is probably a mixture of a Cass 65 is largely the product of anthropogenic number of elements of Sudanian and Sahelianongin, influencesof burning, grazing, and agriculture, with - te WestAfrican Sahel 59 regeneration of vegetation occurring during fallow Gillet, H. 1986. In C. W. Lawson, ed., Plant Ecologyin periods. Consequently, this class is unlikely to offer West Africa. London: John Wiley and Sons, Ltd. fuelwood shortages, considering the fairly low human Granier, C. 1980. In M. Traore, ed., Atlas du Mali. Paris: population densities that exist. Las Editions Jeune Afrique. -m -(International Institute for Envirornment and De- Land Cover Class Tables velopment). 1989."Rainfall in the Sahel. Paper No. 10, September, iucN (International Union for Con- Tables 8-1 through 8-7, beginning on page 60, present servation of Nature) /Sahel Programme. summaries for each land cover class of the area, show- Le Hou4rou, R N. 1980."The Rangelands of the Sahel." ing growing stock and sustainable yield for the West loumalof EWmronmentalManageent 33(1):4146. African Sahelian nations of Burkina Faso, Chad, the Miz, U. 1986. 'Wood Consumption in Traditional Gambia, Malt Mauritania, Niger, and Senegal. Systems in- the Sudano-Sahelian Zone of Burkina Faso." Quarterly Journal of InternationalAgriculture References 25(1):4858. Ndiaye, P. 1983. Atlas du Snidgal. Paris: Les Editions Every effort has been made to facilitate access to the Jeune Afrique. documents listed here. Some documents, however, lack Peyre de Fabregues, B. 1980. In E. Berniss and S. A. fill bibliographic information because it was unavail- Hamidou, eds., Atlas du Niger. Paris: Les Editions able; also, some documents are of limited irculatiorL Jeune Afrique. Sanford, W. W., and A. 0. Ishei. 1986. In G. W. Law- Boudet, G. 1972. "Disertification de l'Afrique son, ed., Plant Ecologyin WestAfrica. London John tropicale skche." Adansonia,ser. 2,12(4):505-24. Wiley-and Sons, Ltd. Daus, Steven J., Mamane Guero, and Lawally Ada. Steentoft, M. A. 1988. FloweringPlants in West Afica. 1986. "A Remote-Sensing-Aided Inventory of Fuel- Cambridge, England: Cambridge University Press. wood Volumes in the Sahel Region of West Africa: White, F. 1983. "The Vegetation of Africa." Natural A Case Study of Five Urban Zones in the Republic ResourcesResearch Series 20. Paris: UNESCO/AEJFATI Of Niger." Paper presented at Symposium on Re- UNSO(United Nations Educational, Scientific and mote Sensing for Resources Development and En- Cultural Organization/Association pour l'Etude vironmental Management, August, Enschede, Taxonomique de la Flore de l'Afrique Tropicale/ Netherlands. United Nations Sudano-Sahelian Office). 60 EstimnalingWoody Biomass in Suk-SalaranAfrica

Table 8-1. Land Cover Classes-Burkina Faso (West African Sahel Region) Area Growingstock Suistainableyield -Thosand Thousandtonnas Land coverclass kmz Percent lonnes Pcent peryear Percent 0 1,792 0.66 0.00 0.00 0.00 0.00 12 5,691 2.10 1,291.86 0.29 56.91 0.39 1 - 5,691 2.10 1,291.86 0.29 56.91 0.39 21 -10,065 3.71 3,321A5 0.74 100.65 0.68 22 158. 0.06 52.14 0.01 1.58 0.01 2 10,223 3.76 3,373.59 0.75 102.23 0.70 44 93,692 34.50 13,210.57 2.94 3,279.22 22.30 4 93,692 34.50 13,210.57 2.94 3,279.22 22.30 5 211 0.08 453.65 0.10 1329 0.09 62 110,555 40.71 295,181.85 65.77 B,512.74 57.89 64 44,053 16.22 117,621.51 26.21 2,026.44 13.78 65 5,164 1.90 13,787.88 3.07 247.87 1.69 6 159,772 58.84 426,591.24 95.05 10,787.05 73.36 81 158 0.06 3,899.44 0.87 465.94 3.17 8 158 0.06 3,899.44 0.87 465.94 3.17

Total 271,539 100.00 448,820.35 100.00 14,704.64 100.00 (Percentage of region) (5.17) (17.96) (14.74) Note:.In the foDowingtables, details may not add to totalsbecause of runding. Source:Authors' cakulations fromdata basesderived from landcover dassification and table4-1.

Table 8-2. Land Cover Classes-Chad (West African Sahel RegiDn) Area Grozingstock Sustainableyield Thousand Thousandtonnes Land coverclass - kn? Percent Ionnes Percent peryear Percent 0 494,756 38.74 0.00 0.00 0.00 0.00 12 23,344 1.83 5,299.09 0.62 233.44 0.75 1 23,344 1.83 5,299.09 0.62 233.44 0.75 21 228,592 17.90 75,435.36 8.78 2,285.92 7.31 22 5,849 OA6 1,930.17 0.22 58.49 0.19 2 234,441 18.36 77,365.53 9.00 2,344.41 7.50 41 3,899 0.31 5,419.61 0.63 8188 0.26 44 230,120 18.02 32,446.92 3.78 8,054.20 25.75 4 234,019 18.33 37,866.53 4.41 8,136.08 26.01 62 210,465 -16.48 561,941.5 65.39 16,205.81 51.81 63 527 0.04 1,407.09 0.16 23.19 0.07 64 26,400 2.07 70,488.00 8.20 1,214A0 3.88 65 29,615 2.32 79,072.05 9.20 1,421.52 4.54 6 267,007 20.91 712,908.69 82.95 18,864.92 6031 73 369 0.03 621.40 0.07 7.01 0.02 74 7.325 0.57 12,335.20 1.44 139.17 0.44 7 7,694 0.60 12,956.70 1.51 146.18 0A7 81 527 0.04 13,006.36 1.52 1,554.12 4.97 8 527 0.04 13,006.36 1.51 1,554.12 4.97 LAkes 15,229 1.19 0.00 0.00 0.00 0.00 Total 1,277,017 100.00 859,402.89 100.00 31,279.15 100.00 (Percentageof region) (2431)- (34.40) (31.36) Sourc: Authors'calculations fiom data basesderived fromland coverdassification and table4-1. ThcWest Afrienji Saliel 61

Table 8-3. Land Cover Classes-The Gambia (West African Sahel Region) Area Growixgstock Su4slainableyield Tlaoussand Thouisandlontnes Landcomr class km2 Pecenit lonones Percent peryear Pcrcent 12 53 0.33 12.03 0.02 0.53 0.01 1 - - 53 0.33 12.03 0.02 0.53 0.01 22 580 3.60 191.40 0.35 5.80 0.16 2 580 3.60 191.40 0.35 5.80 0.16 44 Z740 16.99 386.34 0.71 95.90 2.62 4 2740 16.99 386.34 0.71 95.90 2.62 62 11,856 73.53 31,655.52 58.23 912.91 24.96 6 11,856 73.53 31,655.52 58.23 912.91 24.96 82 896 5.56 22,113.28 40.68 2,642.30 72.24 8 896 5.56 22,113.28 40.68 2,642.30 72.24 Total 16,125 100.00 54,358.57 100.00 3,657A5 100.00 (Percentage of region) (0.31) (2.18) (3.67) Source.Authors' calulations fromdata basesderived fromland coverclassiflcation and table4-1.

Table 8-4. Land Cover Classes--Mali (West -African Sahel Region) AreaGoiigtd Sustainableyield Thousnd Thousandtonnes Landcomer chas km Percent tonnes Percent peryear Percent

0 586,024 46.17 0.00 0.00 . 0.00 0.0 12. 7,957 0.63 1,80624 0.24 79.57 0.30 1 7,957 0.63 1,806.24 0.24 79.57 0.30 .21 264,214 20.82 87,190.62 11.79 2,642.14 10.11 22 4,953 0.39 1,634.49- 0.22 49.53 0.19 2 269,167 21.21 88,825.11 12.01 2,691.67 10.30 41 685 0.05 952.15 0.13 14.39 0.06 44 175,005 14.02 25,098.70 339 6,230.18 23.84 4 178,690 14.07 26,050.85 3.52 6,244.57 23.90 62 146,28 11.52 390,572.94 52.80 11,263.71 43.10 63 8,747 0.69 23,354.49 3.16 384.87 1.47 64 68,662 5.41 183,327.54 24.78 3,158.45 12.09 65 2,582 0.20 6,893.94 0.93 123.94 0.47 6 226,273 17.82 604448.91 81.67 14,930.97 57.14 74 316 02.02 532.14 0.07 6.00 0.02 76 105 0.01 176.82 0.0 1.99 0.01 7 ~~~~~421 0.03 708.96 0.10 8.00 0.03 81 73B 0.06' 18,213.84 2.46 2,176.36 8.33 8 738 0.06 18,213.84 2.46 2,176.36 8.33 Total 1,269,270 100.00 739,753.92 100.00 26,131.13 100.00 (Percentage of region) (24.16) (29.61) (26.20) SourTe Autors' calcudaons fromdata bases deived fromin coverclassifiation and table4-1. 62 Estimating Woody Bfomassin Siab-SaharanAfrica

Table 8-5. Land Cover Cassew-Mauritania (West African Sahel Region) Area Growingstock Sustainableyield Tlhousnd Thousandtonnes Land coverclass km2 Percent toiznes Percent peryear Percent

0 797,596 77.03 -0.00 0.00 0.00 0.00-

21 211,624 20.44 69,835.92 92.85 2,116.24 66.72 22 580 0.06 191.40 0.25 5.80 0.18 2 212,204 20.50 70,027.32 93.10 2,122.04 66.90

41 211 0.02 293.29 0.39 4.43 0.14 44 25,399 2.45 3,581.26 4.76 888.97 28.03 4 25,610 2.47 3,874.55 5.15 893.40 28.17

81 53 0.01 1,308.04 1.74 156.30 4.93 8 53 0.01 1,308.04 1.74 156.30 4.93

Total 1,035,463 100.00 75,209.91 100.00 3,171.73 100.00 (Percentage of region) (19.71) (3.01) (3.18) Soumv:Authors' calculationsfrom data basesdenved fromland coverclassification and table4-1.

Table 8-6. Land Cover Claisses-Niger (West Anrican Sahel Region) Area Growfngstock Sustainableyield Thousand Thousandtonnes Lae. coaer class kn? Percent tonnes Percent peryear Percent 0 710,174 59.95 0.00 0.00 0.00 0.00 12 2,108 0.18 47852 0.36 21.08 0.19 I 2,108 0.18 478.52 0.36 21.08 0.19 21 232,966 19.66 76,878.78 58.49 2,329.66 20.57 22 105 0.01 34.65 0.03 1.05 0.01 2 233,071 19.67 76,913.43 58.52 2,330.71 -20.57 41 632 0.05 878.48 0.67 13.27 0.12 44 229,119 19.34 32,305.78 2458 8,019.17 70.79 4 229,751 -19.39 33,184.26 25.26 8,032.44 70.91 62 6,060 0.51 16,180.20 12.31 466.62 4.12 64 158 0.01 421.86 0.32 7.27 0.06 6 6,218 0.52 16,602.06 1263 473.89 4.18 76 211 0.02 355.32 0.27 4.01 0.04 7 211 0.02 355.32 0.27 4.01 0.04 81 158 0.01 3,899.44 2.97 465.94 4.11 8 158 0.01 3,899.44 2.97 465.94 4.11 Lakes 3,004 0.25 0.00 0.00 0.00 0.00 Total 1,184,695 100.00 131,433.03 100.00 11,328.07 100.00 (Percentage of region) - (22.55) (5.26) (11.36) Sounce Authors'calculations from data bases derived fromland coverclassification and table4-1. 9~~~~~~~~~~~~~~~ The West African Coast Andrew C. Millington

This chapter presents a detailed description of the in northeastern Ghana (100 persons per square kldo- most importantland cover classesin this regiorLHelp. meter) and lowest in Benin and Nigeria (2 persons per ful figure in other chapters include figure 3-1 (cloud square kilometer). In areas of greater population den- cover); figures 3-2. 3-3, and 3-4 (Novmsummary land sity, fuelwood demand undoubtedly exceeds woody cover profiles); figure 3-5 (regional summary map of biomass stock, which is relatively low in tiese domi- land cover classes); figures 7-1 and 7-2 (continental nantly grassland areas. maps of growing stock and sustainable yield); and the "Regional Land Cover.Cass Map of West Africawat Class 44-Sahel-SudanianAcasia Wooded the end of this volume. Bushland Helpful tables in other chapters include table 3-2 (land cover classes); table 4-1 (data and sources for Aazcia wooded grassland and deciduous bushland growing stock and sustainable yield); and table 6-2 occua nlyin the very north of the region, with small (West African Coast estimated woody biomass by areas in northeastem Ghana and the adjacent parts of suxnmaxyclass). Togo and northeaster Benin. The class has its maxi- mum developmentinnorthernNi whereitforms Class 12-Hydromorphic Grassland a broad, continuous belt 50 to 300 kilometers wide across the country, north of 9° N latitude. It accounts Only small patches of Hydromoxphic Grassland are for approximately 7.9 percentof the region, or 163,145 mapped in this region. They form a discontinuous belt square lilometers; the largest proportion is in Nigeria at the foot of the Gambaga Scarp and along the Niger (161,27 square Idlometers). Valley in Benin, and in northern Nigeia. This area In Nigeria, this area is dominated by three vegeta- extends across the inselberg-dominated landscape of tion types-"Burkea africanaSavanna," "Moist Sudan- northwesternNieria as far as the Jos Plateau. Furtier ian Woodland," and "Wooded Savanna.- All tiree small pathes occur to the east of the Jos Plateau at a types are grass and tree savannas, the latter two clas.- similar latitude. Togetlher these areas account for ap- sified as Sudamianand the former as Guinean (Areola proximately 1.86 percet of the region (38,415square 1982a4 In Togo and Ghana, this class falls into the kilometers), the larest area by far being in Nigeria three areas mapped as (a) "Sudanian Savanna" .(33 461sqaekilometers). -,(Brunel 1981;Brookman-Arissah 1987),(b) the north- These areas mainly occur in the "Burkea fiana errmost parts of the 'Dry Forest Zone" in Togo Savanna Zone" as defined by Areola (1982a),although (Brunel 981), and (c) the northenmost parts of the some areas also occur in the norternmost parts of the Guinea Savanna Zone in Ghana (Brookman-Amissah "IsoberfinfaSavanna" and 'Wooded Savanna-' These 1987).A typical Nw curve for this class (figure 9-1) areas are sparsely populated with an attendant low shows a strongly develped seasoriaity with gener- cultivation density; the graslands themselves are ally lower NMvlevels than the Sudni Woodlands used mainly for cattle grazing. (Casses 62,64, and 65) to the south. The fuelwood demand in these areas is widely van- The drier areas are domnnated by a short, fealthey, able. On the basis of population denity, it is greatest condnuous grass sward whiwhattains a height of only

64 The West African Coast Andrew C. Millington

This chapter presents a detailed description of the in northeastern Ghana (100 persons per square kdlo- mostimportantlandcoverclassesin thisregion.Help- meter) and lowest in Benin and Nigeria (2 persons per ful figures in other chapters include figure 3-1 (cloud square kilometer). In areas of greater population den- cover); figures 3-2, 3-3, and 3-4 (NDwIsummary land sity, fuelwood demand undoubtedly exceeds woody cover profiles); figure 3-5 (regional summary map of biomass stock, which is relatively low in these domi- land cover classes); figures 7-1 and 7-2 (continental nantly grassland areas maps of growing stock and sustainable yield); and the 'Regional Land Cover.Class Map of West Africa" at Class 44-Sahel-Sudanian Acacia Wooded the end of -thisvolume. Bushland Helpful tables in other chapters include table 3-2 (land cover classes); table 4-1 (data and sources for Acacia wooded grassland and. deciduous bushland growing stock and sustainable yield); and table 6-2 occurs only in the very north of the region, with small (West African Coast estimated woody biomass by areas in northeastern Ghana and the adjacent parts of summary class). Togo and northeastem Benin. The class has its maxi- mum developmentin northern Nigeria where it forms Class 12-Hydromorphic Grassland a broad, continuous belt 50 to 300 kilometers wide across the country, north of 9g N latitude. It accounts Only small patches of Hydromorphic Grassland are for approximately 7.9 percent of the region, or 163,145 mapped in this region. They form a discontinuous belt square kilometers; the largest proportion is in Nigeria at the foot of the Gambaga Scarp and along the Niger (161,827square kilometers). Valley in Benin, and in northern Nigeria. This area In Nigeria, this area is dominated by three vegeta- extends across the inselberg-dominated landscape of tion types-"Burkea africanaSavanna," "Moist Sudan- northwestern Nigeria as far as the Jos Plateau. Further ian Woodland," and "Wooded Savanna." All three small patches occur to the east of the Jos Plateau at a types are grass and tree savannas, the latter two clas-- similar latitude. Together these areas account for ap- sified as Sudanian and the former as Guinean (Areola proximately 1.86 percent of the region (38,415 square 1982a). In Togo and Ghana, this class falls into the kilometers), the largest area by far being in Nigeria three areas mapped as (a) "Sudanian Savanna" (33,461 square kilometers). (Brunel 1981;Brookman-Amissah 1987),(b) the north- These areas mainly occur in the "Burkea africana ernmost parts of the "Dry Forest Zone" in Togo Savanna Zone" as defined by Areola (1982a),although (Brunel 1981), and (c) the northernmost parts of the some areas also occur in the northernmost parts of the Guinea Savanna Zone in Ghana (Brooknan-Amissah "IsoberliniaSavanna" and "Wooded Savanna-" These 1987). A typical Novi curve for this class (figure 9-1) areas are sparsely populated with an attendant low shows a strongly developed seasonality with gener- cultivation density; the grasslands themselves are ally lower Nrowlevels than the Sudanian Woodlands used mainly for cattle grazing. (Classes 62,64, and 65) to the south. The fuelwood demand in these areas is widely vari- The drier areas are dominated by a short, feathery, able. On the basis of population density, it is greatest continuous grass sward which attains a height of only

64 77TeWesl Afrca i Coast 65.

Figure 9-1. NOVI Profiles, Sahel-Sudanian Acacia remaining trees have multiple use, and their potential Wooded Bushland (Class 44) as fuelwood is limited. This, combined with the rela- tively low sustainable yield for trees and shrubs in this 0.6 class (0.35 tonne per hectare per year), means that 0.5 these areas are suffering from a shortfall in woody D.5- biomass. 0.4 Class 62-Dry Sudanian Woodland z.. Pry Sudanian Woodland occurs in a belt covering the 0.2 / - 44 NotherstemGhana northemmostparts of Guinea-Bissau,Guinea, Ghana, -. -44 Northeastern- Togo, Benin, and northem Nigeria. The main areas in (Hoo State) Nigeria this belt are: . . ~~~~~~~(BornoStale) -*.

Jan Fcb Mar Apr May J.'n Jul Aug Scp Oct Nov Dcc * In Nigeria, a discontinuous belt runs between 7a N and 13" N, attaining its greatest areal extent in 1.5 meters. Interspersed in this grass sward are short Bauchi, Bomo, and Sokoto states. savanna trees dominated by Acaciaspp. Och-ercom- * In Ghana, the class extends southward in a strip mon trees are Adansoniadigitata, Burkea africana, But along the Black Volta as far as Dochire and over a rospermnumparkii, Capparisspp., Conimiphoraafricana, large area in northeastern Ghana, which extends as Diospyros thespilifjrmis, Maytenus senegalensis,and far south as Tamale. Tamarindus indica. The dry woodlands that are * In Togo and Benin, an almost continuous belt runs mapped within this class are dominated by trees such across the northern part of these countries. In Togo as Adansoniadigitata and Isoberliniadoka. These latter it occurs only north of 100N, but in Benin it occurs savanna types covered by this class range from tree- as far south as Banikoara and KCandias well as in a less grass savanna to savanna woodland with a more- strip along the Chaine de l'Atakora. or-less closed canopy and occur mainly in the south of the mapped area. Dry Sudanian Woodland covers 192,338square kllo- Land use in this class is dominated by extensive meters (about 93 percent of the land area), making it grazing and intensive cultivation of both food crops the fifth-largestland cover class in the region (table9-1). (beans, millet, and sorghum) and cash crops (cotton, This is one of the driest savanna woodland classes groundnuts, and tobacco). The population density in in the WestAfrican coastal region. The only drier class parts of this zone can be great-for example, 20 to 39 that occurs to any significant extent is Sahel-Sudanian persons per square kilometer in CirconscTiptionAd- MAcciaWooded Bushland (Class 44). Although the ministrative de Dapadong in northern Togo (Gu- latter class is restricted mainly to Nigeria, Dry Sudan- Konu 1981a). Typical of these areas of dense-popula- ian Woodland is far more widespread. Brooknan- tion are the Kano and Sokoto Close-Settled Zones in Amissah (1987)maps Dry Sudanian Woodland as the northem Nigeria. Between the population concentra- most northerly of the "Guinea Savanna Woodlands" tdons are areas with very low densities and conse- in Ghana. In the adjacentparts of Togo, Dry Sudanian quently a greater frequency of woodlands. Woodland falls within the dry northem parts of Conversely, population pressure leads to great cul- Brunel's "Foret Seche" zone (1981). In Nigeria, it tivation density; an example is parts of Bauchi and Kaduna states in Nigeria and the Savanes Region of Table 91. Areal Distribution, DrY Sudanian Togo (Afolayan and Barbour 1982;Gu-Konu 1981b). Woodland (62),West African Coast Region Population pressure also creates high stock numbers; C an example is the more than 80 million cattle in the Clasn -Cla.si Savanes Region (Gu-Konu 1981b; National Atlas of Country (km?) (percent) (percent) Ghana). Asaconsequenceofthesehighcultivationandstock Nigeria 154,134 80.1 17.2 densities, the woody biomass resource in this class is Ghana 18,233 9.5 97.9 underseverepressureinsomeareas.Landalreadyhas Togo 11,4354,268 2.2795. 7.9 been extensively cLearedfor cultivation and grazing Guinea 2,793 1.5 1.2 over much of this class in Benin, Ghana, Togo, and in Guinea-Bissau 1,475 0.8 4.9 many parts of Nigeria. In areas of low population Thb1 192,338 100.0

density, particularly northem Migeria, the woody bio- _ mass condition is much more favorable. Many of the S- o Authors'data bases. 66 EseimafiingWoody Biomass in Stb-Snaharant Africa corresponds to the northern parts of these types of Figure 9-2. NDvl Profiles, Sudanian Woodland savanna: "Moist Sudanian Woodland," "Wooded Sa- (Class 64) vanna," and "Burkcaafticana Savanna" (Areola 1982a). - - The area is dominated by very open tree and shrub 6 savanna, and it is a drier variant of the closed-canopy 0.5- savanna woodland to the south. The main trees and shrubs include Adansoulia digitata, Burkea africana, 0.4. Butyrospermianparkii, Cardeniaspp., Comnbretumspp., Entadaafricana, Hypl#aene tmebaica, Isoberlinia doka, Parkia 0.3\ spp., and Terniinalia spp. The understory grasses are 02 - dominatedby Andropogonspp. and Hyparrlteniaspp. - - 64 Stemgo In Nigeria, land use in this class varies from inten- sively cultivated and grazed savanna in the east to - 64 Guinea-Mall areas of very low cultivation density and only moder- ° .bd ate grazing on the Benin border. (Areola 1982b). The an Feb Mar Apr May Jun Jul Aug-Sep Ocl Nov Dc intensity of cultivation and grazing reflects popula- tion-distribution (Afolayan and Barbour 1982). Crop- from the Gabti Region in eastem Guinea-Bissau to the ping is dominated by subsistence sorghum cultiva- Nigeria-Cameroon border. Sudanian Woodland is tion, but cotton and groundnuts are the main cash very extensive in Guinea, occurring on the plains be- crops. Similar crop combinations exist in the other tween the Sankarani, Niger, and Tinkisso rivers, and parts of the region covered by this class. on the higher ground along the Mali border. Its occur- Population density in this zone is generally low: <19 rence in C6te d'lvoire is restricted to areas north of persons per square kilometer in Togo (Gu-Konu 90303N where mean annual rainfalj is less than 1,300 1981a) and 2 persons per square kilometer in Nigeria millimeters. (Afolayan and Barbour 1982).Tnis suggests that fuel- . Sudanian Woodland covers large areas in north- wood demand is probably quite low except around western Ghana and between Tamale and the Togo the main settlements. Nevertheless, standing stock Hills. In northern Togo and Benin, it occurs between and sustainable yield in this zone are low and, 9030'N and 1130' N. In Nigeria, it covers most of the although they probably meet current demand, any Nigerian "Middle Belt," demarking a broad tract of increase in population could reverse this favorable high ground from the Benin border in the west to the situation. Jos Plateau and then southward to include the middle Benue River Valley. Class 64-Sudanian Woodland White (1983)classifies this and a number of other land cover classes as "Sudanian Woodland with abun- This is the second most extensive land cover class in dantlsoberlinia"and a "Mosaic of LowlandRainForest the region and occurs in aLl rine countries except andSecondary Grassland."TheNrMOcurve(figure9-2) Liberia (table 9-2).It covers 381,040square kilometers, shows a seasonality similar to the Guinean Woodland approximately 18.5 percent of the area, and extends (Class 74, figure 9-3) but with slightly lower NVI val- ues during the wet season. In Guinea-Bissau, ttis and other land cover classes Table 9-2. Areal Distribution, Sudanian Wood- havebeen classified as (1) "Dry ForestTypes including land {64), West African Coast Region Tree Savannas" (2) "Foret Demi-s&he Dense et Classin Classin Claire" and "Foret Claire Degradee et Savane Boisee" Area region country by scEr (Bianchi 1986), and (3) "Savane Boise" and Country (kitm) (percent) (percent) "Savane Tres Claire" by Atlanta Consulting Gmb.K Nigeria 153,765 40.4 172 (Bianchi 1986). In northern C6te dIvoire, Monnier Guinea 103,283 27.1 43.2 (1983) classifies this land cover type as "Sudanian Ghana 47,110 12-4 19.8 Savanna." In Ghana, this land cover is classified in Benin 40,839 10.7 35A conjunction withvery large parts of central and north- C8ted'Tvoire 16,546 4.3 5.1 em Ghana as "Guinea Savanna Woodland" (Brook- Ginea-Bissau 15,480 L4 182 man-Amissah 1987). In Togo, Sudanian Woodland Sierra Leone : 2,793 . 0.7 4)0. corresponds to the southern part of Brunel's "Foret Total 381,040 100.0 In Nigeria, this class covers much of the 'Middle Note Detailsmay not add to totalsbecause of rounding. Belt" and represents in part the "Isoberlinia Savanna," Sour=cAuthors'data bases. "Mixed Leguminous Wooded Savanna," "Afzelia -Te WVestAfircati Coast 67

Figure 9- NDvIProfiles, Guinean Woodland and geomorphological characteristics of the area, (Class 74) which in tum are controlled by the underlying lithol- 0.6 .ogy (Stobbs 1963; Millington, Helinisch, and Rhebergen, 1985). 0.5A The area is classified as "Riverain Grassland" by Cole (1968)and the "LopliriTree Savanna/ Boland Swamps OAf4. % Complex". by PAO(1981). The "LophiraTree Savanna" is developed on the thin, infertle soils of the intervening z 0.3 - / / R . high ground and is dominated by stunted, fire-resistant Lophiralanceolata in a grass sward of Cliasmopodium - 74 NorthemGuinea-Bissau caudatum.Theecological development of this vegetation O.l- . \~ 74 NorthcmSlirm Lgonc is controlled by cultivation, annual burning, and inten- (Kalnadugudisuiet) sive coppicing of the trees. The seasonally flooded grass OJan Fb Mar Jun Jul Aug ' ' and herb swamps between the interfluves (known as bofis) are almrost treeless and have been extensively cleared for swamp rice cultivation. Savanna/Semideciduous Forest," and "Leg- ninous Apart from the Sierra Leonean "bolilands," this class Wooded Savanna of the Jos Plateau" (Areola 1982a). represents mature Sudanian Woodland with low-to- The savanna formations in this class vary from closed moderate levels of disturbance. Therefore, at present canopy savanna woodland (for example, "A ia- levels of fuelwood demand, wood supplies are proba- Savanna/Semideciduous Woodland" in Nigeria and bly assured in the short-to-medium tenn. However, "Foiet lDe-S&he Dense' in Guinea-Bissau)to thicket the Sudanian woodlands in the West African coastal savanna. The spatial variation in savanna formation is region are coming under increasing pressure from caused by variation in both rainfall amount and disti- charcoal producers. Trees are being cut, converted to bution, and in the -moister parts, woodland is well charcoal, and then transported by road to the coastal developed. In such woodland, trees and shrubs form cities such as Abidjan and Accra, where charcoal is an a more-or-less closed canopy over grasses. important domestic fuel. The Sierra Leonean Moisture availability becomes more of a problem "bolilands" represent a worse situation where local farther north ir. this land cover class, and in such areas demand is relatively great and the locally available open-canopy savanna woodland and shrub savanna woody biomass resource is severely limited. occur. There appears to be an overlap with Dry Sudan- ian Woodland (Class 62), but the latter class generally Class 65-Moist Sudanian Woodland represents much drier Sudanian savanna woodland than woodlands in this class. The dominant trees are Moist Sudanian Woodland occurs in scattered patches Aftelia nftkicana,Anogeissus schimperi, Danielliaoliveri, throughout the Sudanian zone of West Africa These Isoberliniadoka, Monotes kerstingii,and Pterocarpusen- patchesoccur westward and eastward fro Omlongitude naceus.Dominant grasses include Andropogon spp., in two groups: (a) a mome-or-lesscontinuous belt from Cteniumelegans,Hyparrheniaspp.,and Loudetiasuperba. eastern Guinea to north-ceLtral Ghana and (b) an area The area covered by this class varies in population from central Togo to the Cameroon-Nigerian border. density. But, apart from the area around principal The first area includes the northern flanks of the towns, density rarely exceeds 50 persons per square Guinea Highlands (the Dongoroma, Going, Kouran- kilometer and is mostly <10 persons per square kIlo- dou, and Tourou ranges). It also encompasses much meter. Cultivation density is therefore moderate, as of C6te d'Ivoire north of 8° N, including a number of are stock numbers. The main subsistence crops are areas above 400 meters elevation (for example, the sorghum and yams. Important cash crops irclude cot- Chaine de Tiemd, Chaine de Madinani, and the Mont ton, groundnuts, and beniseed (Berron and Vennetier Yv6l&-to-Mont Bowe de Kiendi axis) in the Regions 1983; Gu-Konu 1981b; and Nwafor 1982b). du Nord and de l'Est. In the northem region of Ghana, The only large area mapped as this class that does the area extends as far east as Lake Volta. not correspond to the general pattem of Sudanian The second area contains many smaller areas. Two Woodland isin SierraLeone. Here, a tractin thenorth- main concentrations of these occur in Benin: (a) a thin em interior plains is placed in this land cover class. strip of land between Tchaourou and Kalale, which This area corresponds to the "bolilands." This is an includes the towns of Parakou, Pr6r6, andNiki, and extensive area of seasonally flooded hydromorphic (b) the densely populated area to the southeast of grasslands and swamps, with degraded Guinean sa- Chaine de l'Atakora, which includes the towns of vanna woodland on the intervening high ground. The Natitingou, Ouake, Kopargo, Dougou, Pehonko, and vegetation pattem is controlled by the hydrological Kouandc. 68 Estitma4tingWoody Biomna.ss in Sub-Saanmri Africa

Table 9-3. Areal Distribution, Moist Sudanian for grazing. However, around both Enugu and Ilorin Woodland (65), West African Coast Region in Nigeria, edaphic and derived-savanna grasslands, Classill Classinl respectively, are extensively cultivated. This area is A rea region couItntry one of mixed-grain and root crop agricultural systems, Colunitry. (knila) (percell) (percenl) the main subsistence crops being maize, millet, sor- Nigeria 121,252 51.9 23.6 ghum, and yams (Berron and Vennetier 1983; Cu- C6ted'lvolre 43,474 18.6 1344onu1981b;Nwafor1982). Guinea 24,611 10.5 10.3 In thesouthem areasof thisclass, tree and rootcrops Ghana 22,975 9.8 9.7 are more common, whereas in the north, cereals pre- Benin 14,755 6.3 12.8 dominate. Cash cropping is less common than in Togo - 6,165 2.6 11.4 many other savanna woodLand zones in West Africa, SierraiLane 53u >40.1 1.4 although significant tobacco cultivation occurs in Sierra Len3 .northwestern Cote d'Ivoire (Berron and Vennetier Total 233,707 100.0 1983). Crazing is common, although herd sizes gener- Notr:Details may not addto totalsbecauseof rounding. .ally are much smaller than in the drier savanna wood- Sotmre:Authors' data base. land zones to the north. Population density varies from <4 persons per Much of central Nigeria also falls into this class. In square kilometer in many parts of C6te d'lvoire the south, Moist Sudanian Woodland is limited by the (Lecomte and Monnier 1983) to 100 persons per square coastal plains, and it does not extend north of 10° N. It kilometer in parts of Togo (Gu-Konu 1981a). The spa- is the fourth-largest land cover class in the region, tial variation in both woody biomass and population covering 233,707 square kilometers. It accounts for withintheMoistSudanianWoodlandzonemeansthat approximately 11.3 percentof the land area and occurs the firewood supply is extremely variable, ranging in all countries except Liberia (table 9-3). from significant surplus to severe shortage. Moist Sudanian Woodland is equivalent to a num- ber of vegetation classes mapped by Areola (1982a) in Class 74-Guinean Woodland Nigeria-"M[ixed Leguminous Wooded Savanna," "Afrelia-Savanna/Semideciduous Forest," "Moist The area covered by Guinean Woodland in this region Sudanian woodland," and parts of the "Forest-Savanna is very extensive-243,241 square kilometers or about Mosaic." These are mainly savanna communities, the 11.8 percent of the land area. It occurs in all countries exception being the "Forest-Savanna Mosaic," which of the region except Liberia (table 94). is a transitional class between the rain forest and the Asmapped, thisclass isprobably synonymots with savanna woodland to the north. White's "Guineo-Congolian Secondary Grassland In Cote d'lvoire, this class corresponds to thenorth- and Wooded Grassland" (1983) and occurs in a belt ermmost parts of the "Sub-Sudanian Savanna" (Monn- varying between 50 and 950 kilometers wide from ier 1983).These areas are mainly grass and herb savan- the Guinea-Bissau-Senegal border to the Nigeria- nas with either trees, shrubs, or thicket formations. In Cameroon border. In Guinea-Bissau, Guinean Wood- Ghana, this area forms part of the "Guinean Savanna land dominates the higher ground away from the Woodland," but is not differentiated from other sa- vanna types by Brooknan-Amissah (1987). In Togo, Moist Sudanian Woodland is mainly restricted to hills Table 9-4. Areal Distribution, Guinean Woodland above 400 meters elevation, and is classified as "Forat (74), West African Coast Region

Sche" (Brunel 1981). . Classin Classin Despite thefactthatthiszoneisnamedafterasingle Area region country tree, Isoberlinia doka, by many workers (including Country (knr) (percent) rperceno White 1983), it is not a single-dominant community. Guinea 63,024 25.9 26.4. Other equally important trees occur, such as Afzelia C6ted'lvoire 59,598 245 18A africana,Anogeissus schimperi,Daniellia oliveri, Khaya Nigeria 53,064 21.8 5.9 senegalensis, Monotes kerstingii, Pterocarpus erinaceus, Sierra Leone 30,563 12.6 43A and Uapaca togoensis. Important shrubs and small trees Guinea-Bissau 14,491 6.0 48.2 in drier areas include Butyrospermum parkzi, Cardenia T;ao 8,958 3.7 165 Ghana 7,694 3.2 3.2 spp., Combretum spp., Entada afrcana, ParTiaspp., and Benin 5,849 2.4 5.1 Terminalia spp. Cultivation density is much lower in this zone than Total 243,241 100.0 inthe woodland tothe south and nortLhIn many areas, Note: Details may not add to totals because of rounding. extensive tracts of savanna woodland are used only Source:Authors' data bases. TlicWest Afnicani Coast 69 coastal plains (for example, in Bafatd,Gabia, and Oio At a smallscale, the distribution of trees and shrubs. regions).In Guinea and SierraLeone, it occursinithree is controlled by edaphic factors (Clayton 1958, 1961;. distinctareas: Hambler 1964;Jones 1963; Keay 1959;Menaut and Cesar 1979,1982;Morison, Hoyle, and Hope-Simpson * From the northem coastalplains of Gtuineainland 1948;Ramsay 1964; Ramsay and dc Leeuw 1964,1965; as far as Koundara . White 1965).Trees and shrubs usually are best devel- * In an area stretching northward from Bo in Sierra oped on the most fertile soils and here the woody Leone to the Fouta Diallonin Guinea and then back biomassis greatest;however, in these areas, competi- southeastward to Kissidougouin Guinea.This area tion from grnssesis also imnportantand fire is an im- includes the interior plateaus and hill region-of portant factor in savanna formation (Menaut and Sierra Leone and Guinea . Cdsar 1982).Stands of palmns,dominated by Borassus * An area extending from Nzerdkordin Guinea into acthiopuim, are widespread and are tolerant of a wide eastern C6te d'Ivoire. range of environmentalconditions. Menaut and Cdsar(1979,1982) have reported exten- In Cote d'lvoire,Guinean Woodland coversmost of sively on Guinean savannas from the Lainto study the ground between 300and 400meters above sea level area in central Cote d'lvoire (the UNUSCMan and Bi- north of 7°40' N, with the exceptionof the Mt. Bendi- sphere or MADProgramme). At Lamto, a number of ML Ko axis and.some areas in the extreme northeast. vegetationcommunitieshavebeen identified that typify The vegetation is poorly developed in Ghana and. the potentialdiversity of woody biomassstocks in this Beninbutisextensive,albeit ratherpatchy,inTogoand and similar land cover classes (table 9-5). These var- Nigeria. The main occurrence in Nigeria is on land iations are mainly related to topographic and soil higher than 300 meters elevation on the Abeokuta- corditions. lbadan-Ondo axis, along the Niger Valleyas far north On the highest ground at Laamto,freely draining as the Jos Plateau, and on the Bamendaand Mandara ferralsolsare dominated by "AndropogoneaeSava=n- hills.The NOVIprofiles (figure 9-3) show the seasonality nas,' of which five types are recognized.These are all of the vegetationand its intermediatepositionbetween dominated by Andropogonspp. grasses.They are clas- the forestzone and the drier woodlands. sified by woody biomass stock and, in order of de- Rain forest trees within these savannas are either creasing stock,they are: remnants or invasive. The communities themselves are extremelyheterogeneous, ranging from grassland Svannaa* Woodland,in which the trees form a con- through shrubby thicket to well-developedsavanna tinuous canopy between 2 and 6 meters, although woodland and galleryforest. Three strata canbeiden- palms often emerge to heights of 10 to 12 meters. tilled in thesavannas, although they are not present in The trees are underlain by a dense grass sward. all of the communities: . * Dense Shrub Savanna, which has a lower overall tree and shrub cover varying between 20 and 25 * A lower stratum of grasses,herbs, young saplings, percent, with shrubs attaining a maximum height and shrubs attaining 2 meters in height of 8 meters. * A middle stratum of shrubs and small trees which * Open Shrub Savanna, which occurs in areas with vary between 2 and 8 meters better soil conditionthan the transitional shrub and * Emergent trees and palms that exceed8 meters. grass savannas. Consequently, the shrub species

Table .9-5. Woody Biomass Stocksand Growth Rates, Guinean Woodland Communities, Lamto,Cote d'Ivoire Intermediate Open Dense Savanna Parameter shrubsavanna shrubsavanna shrub savanna woodland

Individuals . 120 160 300 800 Canopy cover (percent) . 7 15 20 45 Leaf area index 0.1 0.2 CA 1 Woody biomass Above ground (kg/ha) 7,400 21,900 32,600 -54,200 Below ground (kg/ha) 3,600 9,200 1,430 26,600 Woody biomass growth rate Above ground (kg/ha/yr) 120 330 420 760 Below ground (kcg/ha/yr) 50 130 230 370 SOur7!. After Menaut and Cdsar 1982. 70 ElsimaIingWoody Biomu in Sub-SaharanAfrica

are better developed,attaining ground coversof 15 cattle owners (between 1951and 1963),and by dry- to 20 percent. seasonfarming promoted by smallirrigation schemes. * IntermediateShrub Savanna, whichhas a very low The best examplesof moist closed-canopywoodland woody cover (lessthen 10 percent),with individual now existaround villages,where they are reserved for shrubs ranging from 3 to 6 meters in height. a variety of reasons. * Grass Savanna, which occurs where shallow In the "SouthernGuinean Savanna" of SierraLeone ferricretesrestrict tree and shrub growth,consisting and adjacentareas of Guinea,land use is dominatedby exclusivelyof grassesup to 2.5 meters in height. Fulapastoralism, and thegrassunderstoryisextensively grazed. In northwestern Sierra Leone, the unusual On the hydromorphic gleysols,which characterize "LophiimTree Savanna"occurs in this class(Cole 1968). the slopes down to the rivers, Loutdetiasimplex grass- Here,a combinationof infertle thinsoils, intensive cul- dominated savannas occur. These have a very poor tivation,and fierceannual burning have created an eco- woody element (mainlypalms and shrubs on termite logicalcommunity completely dominated by Lophira mounds) because of various edaphic constraints re- lanceolatain a grass understoryof Chasmopodiuntcau- lated to waterloggingin the gleysols. datum.The treeshave been intensivelycoppiced, both Menaut and Cdsar (1979,1982) also have investi- dunng agicultural clearanceand for fuelwood.Only gated the role of burning on the evolution of tihese shrubbyregrowth remains in most areas,In slightlyless savannas.On the one hand, Loudetiasavannas have a disturbedareas, however, the trees attain 7.5 to 10meters sharp boundary between savanna and forest, espe- in height,and at the edge of the "LophiraTree Savanna" cially in burned areas. On the other hand, An- othersavannatrees are invasive. dropogoneae savannas have a gradual increase in Many parts of the Guinean Woodland are sparsely woody componentfrom open grassy areasto savanna populated, and thus have a low cultivation density. woodland.The foret.t-savannabourdary is dependent Otherareas have a highcultivation density, mainly for on the date, duration, and intensityof firesand there upland (rain-fed)rice in the wetter areas and sorghum is no one definite regionalsuccession, and millet in the drier areas. Vegetationis cut, dried, In some areas, forest trees establishthemselves in and bumed to create fields that are commonlyculti- swamps, on termite mounds, or on rockyoutcrops. vated for up to 2 years. The woodland is then left to These communitiesthen act as precursors for forest regenerateas a woody fallow. invasion, once burning ceases.In other areas, gallery Although older woodland regrowth resemblesthe forest trees may invade the adjacent savannas after climaxsavanna conmmunitiesin structure and floristic herbs have invaded. As the trec canopy closes,the relations,the derived savannas are characterizedbv shading effectrestricts grn.s growth, less fuel for the the frequentoccurrence of the economicallyimportant annual fires is produced, and fires thereforedo not fire-resistantoil palm (Elaeisguineensis) and a greater penetrate the invasive foreststands. proportion of fire-resistanttrees because of the fre- Cole (1968)recognizes a moist savanna woodland quent burning.Fire-resistant and fire-tolerantsucces- in northeastem Sierra Leone which he tenns the sionaltrees (forexample, Lophira alata, Parkia biglobosa, 'South Guinean Savanna." It grades from moist Piliostigmathonningii, Pterxarpus erinaceus, and Syzyg- woodland on the wetter soils to a shrub or grass ium guineense) first occur in the younger regrowth savanna on mountain slopes. Moist woodland and stagesand becomesubdominant in older successions. open tree savanna are the dominant ecologicalstruc- Theyare alwaysan importantcomponent in the Guin- tures: In the moist woodland and tree savanna, the ean Woodlandcommunities, however, because of the treesaregnarled,stunted,fire-resistantDanielliaolivei annual burning of the understory grasses to create and Lophtiralanceolata, attaining heights of 10 to 17 better grazing for cattle in the woodlands. meters, growing in a dense grass understory.On thin- The GuineanWoodland class is dominated mainly nersoilswithlesscapacityforholdingmoisture,shrub by well-developedclosed-canopy woodland with a and tall grass savannasdominate. In the "SouthGuin- moderately high sustainable yield. This, combined ean Savanna"zone, galleryforest mixes savannatrees with the variablebutgenerally low populationdensity (for example,Cussonia longissima, Parkia biglobosa, and (2 persons per square kilometer), suggests that few Terminaliaglaucescets)with rainforest trees (especially woody biomass supply problems exist, although Chlorophr.aregia, Erythrophleum guineense, Parinai ex- localizedproblems undoubtedly occur(for example, relsa,and ltapacaguineensis). in the "LophiraTree Savanna' in Sierra Leone). In Coleargues tihatmoist semideciduouswoodland is many WestAfrican states, this situationcould change the climaxcomnmunity on the best soils,bult that deg- with a switch in charcoal production for coastal radation of these woodlandsin norhern SierraLeone towns from Sudanian Woodland (64) to Guinean has been caused by dry-season buming to promote Woodland. The high-density wood thEatis character- better grazing, by settlement schemes for nomadic istic of trees in the Guinean Woodland would pro- The West African Coast 71 duce high-qualitycharcoal if the supply fromSudian- tains on the SierraLeone-Liberia border and central ian Woodland becamescarce. Ghana, and (b) in southern Nigeria, mainly in Bendel State and the Cross River Basin. Small Overview: West African High Woody patches also occur in eastern Guinea, central Cote Biomass Mosaics d'Ivoire, and in the Atacora Mountains on the Ghana-Togoborder (table 9-6a).The class is mainly The humid tropical forest zone in West Africa is restricted to the lowland plains and plateaus of the densely populated, and only in a few areas do exten- coastal belt. For example, in C6te d'Ivoire, it occurs sive tracts of primary or mature secondary forestre- mainly within 150 kilometers of the coast at eleva- main. Much of the area is clultivated,the two main tions below 200 meters, although it also exists on agriculturalsystemsbeingbushfallowingandplanta- Mont Bowe de Kiendi and Mont Nangbion. Other tion cropping. Consequently, the land cover of the occurrences on higher ground are, for example, in region is a complex mosaic of primary forest and the Loma-ManDorsale. mature secondary forest reserves, various stages of The class covers 101,438square kilometers,about forestregrowth, cultivated fields, and plantations.The 4.9percent of the totalarea. Itsgreatestextent is inC8te fragmentarynature of land use is such that individual d'Ivoire (47,584square kilometers),followed by Libe- elements cannot be routinelyidentified and mapped ria (24,925 square kilometers) and Ghana (18,812 using 8-kilometerresolution data. square kilometers). After extensivediscussion with forestersand land Rainfallis great overmost of the area mapped in this. use planners from West Africa,we mapped the area class, ranging from about 1,400 to more than 4,000 as a high woody biomass "Mixed Agriculture and millimetersa year in most areas. In Ghana,however, Forest Fallow Mosaic."We divided the mosaic into the classoccurs in areas with as littleas 1,000millime- two phases, based on overall levelof productivity: ters annual rainfalLTo a large extent, the greater pro- ductivity of vegetation in this class is due to rainfall HHigh-Productivity West African Cultivationand But evidence also exists for a minor depression in Forest Mosaic(Class 75), correspondingroughly to photosynthetic activity in the wet season, approxi- the evergreenor ombrophiloushumid forestzone mately in August, in Nigeria, Togo, and Ghana, a * Medium-ProductivityWestAfricanCultivationand period known as the "little dry season." In the more Forest Mosaic(Class 76), corresponding roughly to westerly areas covered by this class, rainfall is re- the semideciduousor mesophilousforest zone. stricted to a single wet season with a dry season rang- ing from 4 to 6 months. The pattern of vegetation Class 75-High-Productivity West African response to rainfall is reflected in the NDviprofiles Cultivation and Forest Mosaic (figure9-4). Much of the humid tropicalforest that oncecovered This mosaic occurs along the coastalbelt of West Af- this area has been cleared.White (1983) reported three rica in two main areas: (a) between the Gola Moun- types of wet lowland rain forest in this area; 'Hygro-

Vable9-Sa. Areal Distribution High-Productivity Table 9-6b. Areal Distribution, Medium- Cultivation and Forest Mosaic (75), West African Productivity Cultivationand Forest Mosaic (76), Coast Region West African Coast Region Classin Classin Class in Classin Ara region cuntry Area region country Country (km2) (percent) (percent) Country (rm2) (percent) (percent) Cote d¶Ivoire 47,584 46.9 14.7 Cote d'Ivoire 150,023 26.8 46.3 Liberia 24,925 24.6 265 Nigeria 132,739 23.7 15.2. Ghana - 18,812 185 Ghana 99,383 17.7 44.6 Nigeria 7,641 7.5 0.9 Liberia 60,494 10.8 64.3 Togo 1,107 1.1 2.0 Benin 38,046 6.8 33.3 Guinea 1,001 1.0 0.4 Guinea 31,512 5.6 13.2 Sierra Leone 369 OA 0.5 Sierra Leone 27,981 5.0 39.8 Benin 0 0.0 0.0 Togo 18,865 3.4 34.9 Guinea-Bissau 0 0.0 . 0.0 Guinea-Bissau 1,739 0.3 5.8 Total 101,439 100.0 Total 560,782 100.0 Notr Detailsmay not add to totalsbecause of rounding. Note:Details may not add to totalsbecause of rounding. So. Autlohos' data bases. Source: Authors' data bases

*t d . - .0 72 -EsiiirnlngWoody iottmassinSub-So/laran Africa

Fig,ure9-4. NDVI Profiles, High-ProductivityWest "MixedMoist Sendi-EvergreenGuineo-Congolian African Cultivation and Forest Mosaic (Class 75) Rain Forest"

0.6 This type is less developed in West Africa than -Hygrophilous Coastal Evergreen Guineo-Congolian 0.5- / Rain Forest." White (1983)attributes this to the abrpt 0.4- DA t \ transition from very wet coastal conditions to the dry 0,4r \ - interior. Areola (1982a) describes "Moist Lowland 0.3-| / - - \, - Forest" in southern Nigeria as typically having the -thre layers associated with tropical rain forest: the 0,2- upper layer of emergents 40 to 50 meters high, a mid- 75Southwestem Ghana dle layer of trees betw e.n 16 and 40 meters, and a 0.1 -75 SouthwesternMCe d'lol lower layer of trees varying between 10 and 16 meters. 0 an MrArMy(EindSdQus)The uipper and middle layers foDrmone continuous -Jan Fb Ma Apr MayJun Jul Aug Sep Oct Nov Dc canopy and the lowerlayerformsasecondcontinuous canopy. Underneath are shrub and herb layers with saplings of the taller trees. philous Coastal Evergreen Guineo-Congolian Rain In this class, the mean deciduousness in Sierra Forest," "Mixed Moist Semi-Evergreen Guineo- Leonean forest reserves was 23.5 percent (Cole Congolian Rain Forest," and "Single-Dominant Moist 1968),although other forests classed as evergreen by Evergreen and Semi-Evergreen Rain Forest.' Little Cole had deciduousness values from 16.5 to 26.2 forest now occurs in the region because of extensive percent. cultivation of food and plantation crops. Forest still This type of forest corresponds to Monnier's occurs, however, in less densely populated areas and "Foret Ombrophile" (1983), which occurs south of in forest reservations. the 1,600- millimeter isohyet in C6te d'Ivoire. It is characterized by emergents such as Lophira alata, -Hygrophilous Coastal Evergreen Guineo- which attain a height of 50 meters. hn Sierra Leone, CongolianRain Forest" this type of forest occurs in the Cola Mountains on the Liberian border and spills across the border into Of the three forest types, this was the most common Lofa County in Liberia. Other interior evergreen in West Africa. Hall and SwaLte (1976) describe humid tropical forests in Liberia (in Montserrado, 'Hygrophilous Coastal Evergreen Rain Forest" as Grand Bassa, Grand Gedeh, and Sinoe counties) shorter than "Mixed Moist Semi-Evergreen Rain For- probably fall into White's "Mixed Moist Semi-Ever- est," with an upper canopy attaining 30 meters and a green Forest" class. Cole (1968) notes that when the few emergents attaining 40 meters. Gola Forest was first enumerated in 1923, "...most The evergreen characteristic of the forest is caused of it was virgin primary rain forest and even areas by most species shedding their leaves intemrmittently, which had been disturbed by man, had secondary although in areas with a pronounced dry season (for forests of considerable age." example,Liberia and Sierra Leone), manyspeciesshed Dominant canopy trees are Ant/sonothafragrans. their leaves simultaneously and are immediately re- Combretodendronspp., Cynometraleonensis, Chrysophyl- placed withnew ones. This type of forest is equivalent lumspp., Diospyrosspp., Entandrophragmaspp.,Guarea to "ForAt Hyperombrophile" in Cote d'Ivoire (Mon- spp., Lophiraalata, Naucleadiderrichii, Oldfieldia afric- nier 1983), which occurs only in areas with a mean ana, and Tarietiautilis. annual precipita don exceeding 1,800 millimeters and a reduced dry season. "Single-DominantMoist Evergreenand Semi- This type undoubtedly occurs in Liberia, but Jansen EvergreenGuineo-Congolian Rain Forest" (1972) does not differentiate it from other evergreen humid forest types. He does, however, record "Wet This type is interspersed within the other two types. Coastal Rain Forest" vegetation dominated by Tetra- Single-dominant forest is much rarer in West Africa berliniatubmaniana in a belt that stretches inland about than in the Zaire Basin and is mainly restricted to the 80 kilometers between River Cess and Greenville in wetter evergreen forest along the coast White (1983) Liberia. The canopy dominants of this forestare Crudia notes that only two of the dominant trees in the Zaire gabonensis, Didelotiaunifoliolata, Gilbertiodendron pre- Basin extend intc southem Nigeria: Gilbertiodendran ussd, Gluma ivorensis,Lophima alata, Mapania spp., Tar- dewevreidominates some fringing forests or swamp ietia utilis, Terminaliautilis, Tieghemella(Dumonria) fric- forests, and eulbernardiaseretii occurs within the ana, and Sacoglottisgabonensis. coastal evergreen forest. Single-dominant forest is TireWesI African CoasI 73

Figure9-5. Cbted'lvoireWoodProduction,1980-84 biomassreserve mean that fuelwoodsupply problems are, at worst, only localized. 5 \ The main problem facing the woody biomass resourcein this area is exploitationof hardwood tim- 4 _ _ - lberby localcontractors and under concessionto for- eigncompanies. Valuable hardwoods such as Oldfieldia - -afJrcana,Khaya spp., Enlandropbrgrngnaspp., Turraeanthus 3 africana,Cluloroplrora excelso, and Tiegherneilahockelii all are harvested from these forests (Cole 1968;Arnaud 1983).The trade in timber is of great importance in _...... -.-----.--...... Ghana,Cote d'Ivoire, and Liberia (for an example in I - Uxpoit Cote d'lvoire,see figure9-5). Comparison of the qual- 'R - E 'ity of timber felledin Cote d'Ivoire in 1980and 1984 - Torn shows a slight deteriorationin quality(figures 9-6 and 0 --.Industral 9-7) that might be expectedwith overexploitation. 0-~ 3980 1991 1982 1983 1984-: -980 -921 -982 1983 1984 Class 76-Medium-Productivity West African Cultivation and Forest Mosaic dense, typically35 to 45meters high, and iscomposed almostentirely of one species. This mosaicoccurs in all nine countriesin the region Someareas in the high-productivityzone stillhave (table 9-6b),extending from the Tombali Region in extensivemature secondaryevergreenhumid tropical Guinea-Bissauto the Nigeria-Cameroonborder. In forest These areas always occur where population Guinea-Bissau,it is restricted to the TombaliRegion. density is low. For instance, in southwestern Cate An extensive area in Guinea runs from the Fouta d'Ivoire (Regiondu Sud-Ouest),population density is Djalionfoothills to the ForecariahPlains. The coastal <10persons per square kilometer,and most of these and interiorplains of southernSierra Leone and Libe- people live in a few coastal towns or along roads. ria formanother large contiguousarea, includingthe Consequently,cultivation density is low andlivestock forestedsouthern interior plateau, parts of the Gola, herds are smallin these areas. Gon, and Niminihills, and the Upper Moa Basinof In Sierra Leone,Liberia, Cote d'Ivoire,and Ghana, SierraLeone. populationdensities are much greaterand forestclear- The mosaiccontinues across much of the southern ance for arable and tree crop cultivationis common. half of C6te d'Ivoire into Ghana, where three main The main crops are nce and cocoa, although some areas exist: (a) on high ground to the west of Sun- extensiverubber plantationsin Liberiaare mapped in yani, (b) around Lake Volta in the center of the hisciass.Thelowpopulationdensityandhighwoody country, and (c) on the Accra Coastal Plains. This

Figure 9-6. Cote d'lvoire WoodProduction by Figure9-7. Cote dIvoire Wood Productionfby Class, 1980 Class, 1984

2000O-a. Mixed woodsofsuperor 2 la Mixedwoodsorsuperior qualityincluding rcdwoods: qualityincluding redwoods: lb. Othermibxedwoodsor b.- Othermixed wood.sof supeirualy quality. .spror 27 M3wtomwry, 2. Mixed woods; iney. 2 ixedywoods:faier plywood.furnitur1--el. e I Supediertliiyjoinery woods. | 3. Supe nery woods. 4.Jinrwod. 4. iie~wos S.5ttecrsandmouldings. 5 -necrs ndmouldings. o. Hrdwods (reainsandjoits). 6. Hardwds (fiaamesand joists). 7. Otherc .7. Otherclses. ID E1000E C

1D ~~ ~ ~ ~ ~ ~ lb.~ 2.~ ~~~~I.3. 4. n.I 6. 7. 5. ,: E . - -. -.,-;~~~~~~~~- R - ~ ~ ~ ~--- 1 ff lb. 2X,; 3. 4 . 6 -7. la. l. :2. 3- 4X- . 6 - 7.X- .

: ::- g f i - . . . - ~ ~ * . Tlx WestAfrican COast 75

Figure 9-A NovIPrOfileS, Medium-Productivity narrowcoastalstripatTabou,No-Mer,LaguneTalo, West African Cultivation and Forest Mosaic Lagune Ebrie, dnd Lagune Ehi. These savannas are (CIass 76) dominated by a dense grass cover of Bnichianabrachy- -lapa,Hyparrlaenia cdiryjsara, aandLoudetia piragmi- toides.Trees occur in the grasslands and, in a few places, are remnants of large forests with typical rain forest trees such as Brideliafergineaand Ficuscapen- OA sis, although Adjanohoun (1962)ascibes thir origin to wooded savannas. 0.3- Two hydromorphic graland communites have -76-. been recognized in Sierra Leone: 'Riverain Grass- 02tPIdehn dUUfflSa c lands" and "Grass-HerbSwamps" (Cole1968). River- 0.1 - ain grasslants occur extensively along the lower 7 (W du Ceitmi ck - courses of the Sewa and Waargjerivers and are comi- -OanFdar Ap M nl.g e nated by grasses, sedges, and herbs,-the only com- monly occurring shrubsbeingAnthostemasegalens, C-..l rto iafic#Wia,Croton scardesii, Dissotis cornifolia, shrubs. However, witiin the grasslands, shmbby and Hyptis spzcige,. The wetter parts of the coastal thckets occur on old trmite mounds. These thickets. savanna zone of Liberia around Greenville, Harper, form a dense, cdsed anopy of Capparisaytnocpr, and River Cress are also mapped in this class. These Flcirtia zndiazfvescns), Grewianpulwa, Seawqa are assumed to be areas of denved savanna (Voor- wwuz, Uaria c1wa, and Anmiylnm xmllwxylods hoeve 1968)or hydromorphic grassland. about 5 meters high with airirts up to 10 metec of Elaphwibiadnqpxenz and Dkymos mspilJbrmis. Origin On irgs, patches of evergreen and semi-ever- gren coastal forest have developedsince the cessation In its northeumnost occurrenes, this land cover class of farming (Swame,liebemian, and Hall 1990) These forms one of the main ecotones between the humid aremultlayeredlike therain forest, althoughtheyrarely tropical forest and the wetter savanna woodlands to exceed 10 to 12 met in heigh The dominant canopy the norti aracteristically, this area contans both trees are CynomeU megaphylla,Diaspyns abyssinac, D. rain forestand savanna elements. The former occur as espimnnis, Mnlhla obouxl, and Miettia thoiningiL small areas of senidedduous rain forest and gallery The lower layer is chAy- composed of Dnjpetaflori- forestalongnversthataresetinlargetractsof wooded bunda,D. pv*lia*and Veprisheiero* la Emergents savanna. such as Anti aristoxicaria, Ceiba pentandra,,Cellis One body of researches says that much of the sa- mldbmalkiand Nesogordmiapapea also exist. vanna is maintained by fire and terms it "derived The ecology of a forest on an inselberg differs from savanna.' They argue that, if bumrig ceased, the rain that of the rain forest because irselberg forest is forest would invade dtese areas and they cite evi- shorter, lacks evergreen tree species, and has a poor dence of remnant humid tropical forest areas in the regeneration rate from seed. he agricultural pattem. savanna and the exisene of fire-tolerant and fire- is similar to that elsewhere in the land cover lass. resistant trees to support this hypothesis- Anotherbody of researchersquestions thisinterpre- Grassland tation on the basis of the sharpness of the forest- savanna boundary and the lack of penetration of fires *Guineo-Congolian Edaphic Grassland," which oc- into roist forests This lends credence to the hypoth- curs on hydromorphic soils throughout the region, is esis that,beforecultivationandburningintheseareas, alsomapped withinthis land cover cass.Wlite (1983) a continuum of vegetation existed from rain forest to suggests that most of these grasslands represent tran- dry savanna (lioplins 1974;Keay 1952;Swaine, Hall, sitions between aquatic vegetation and forest, -the and Loc 1976). grasslnd structurebeing maintained by annual bum- in& Meraut (983) co Qsidersthese to be 'Coastal Population and Agriculture Grass Savanas"k in C6te dlvoire and suggests that many are.fire-prodimax communities derived from Population density varies in the area covered by this forests or wooded savannas (Adjanohoun 1962). class. Where it is low, forest and woodland areas Nevertheles, truly hydromorphic grasslands rec- daminate, but in areas of greter -pulation density, ognized in Coe d'lvoire (7Savanes de Basse C6te" or forests are cleared extensvely. M.Li large cities and "Savanes Lagunaims) occupy small tracts along a towns in the region are situated in this class, and

.. -,* . . - , . . ThieWest African Coot 75

Figure 9-a NDVI Profiles, Medium-Productivity narrow coastal strip atTabou,Nero-Mer, Lagune Taio, West African Cultivation and Forest Mosaic Lagune Ebrie, dnd Lagune Ehi. These savannas are (Class 76) dominatedby a dense grass cover of Brachiiariabnrcly- - lopha,Hyparrhenia clirysargyrea, and Loudetiaphragmi- toides. Trees occur in the grasslands and, in a few places, are remnants of large forests with typical rain : 1 - DA/forest trees such as Brideliaferrugi'neaand Ficuscapen- OA- < 7 \ / / \\ sis, although Adjanohoun (1962) ascribes their origin 0.3sc3' \tr.."' to wooded savannas. -0.3-ii 'Two hydromorphic grassland comnmunitieshave. 0.2 -76-outheastern . S-erra A- -been recognized in Sierra Leone: "Riverain Grass- 0.2 76So(Pujhurndisiact) - lands" and "Grass-Herb Swamps" (Cole 1968).River- 0.1 -76 WesternCenirni C6te divoiro ain grasslands occur extensively along the lower 76 WestemCcntml Cbto dlvivde (Rcgiondu Centre-Oucst) . courses of the Sewa and Waanje rivers and are domi- o- | . | -1- ,J,J , , J ,NovnatedI by grasses, sedges, and herbs, the only com- Jan Fe bwMa pr day Jlma Jual.Aug Sep Oct Nov Dec ..n .ebMar A.r May AugSep Dee monly occurring shrubs beingAnt hostemasenegulense, Clappertoniaficifolia, Croton scarciesii, Dissotis cornifolia, shrubs. However, within the grasslands, shrubby and Hyptisspicigera. The wetter parts of the coastal thickets occur on old termite mounds. These thickets . savanna zone of Liberia around Greenville, Harper, form a dense, closed canopy of Cparis erythmrpos, and River Cress are also mapped in this class. These Flacourtiaindica flGvesces), Grewia c imfua, Securinega are assumed to be areas of derived savanna (Voor- - irosa, Uvana chamae, and Zanthoxylumn xanthoxylokdes hoeve 1968) or hydromorphic grassland. about 5 metes high with emergents up to 10 meters of Ek-kwphorbiadrup*fr and Diospyrosmespilifoniis. Origin On inselbergs, patches of evergreen and semi-ever- green coastal forest have developed since the cessation In its northermnost occurrences, this land cover class of farming (Swaine, Liebemnan, and Hall 1990).These forms one of the main ecotones between the humid are multilayered like the rain forest, although they rarely tropical forest and the wetter savanna woodlands to exceed 10 to 12 metes inheight The dominant canopy the north. Characteristically, this area contains both trees are Cynometramegalophylla, Diospyros ayssinica, D. rain forest and savanna elements. The former occur as mespiifjbrnis,ManilAm oborzta,and Miffettiathonningii. small areas of semideciduous rain forest and gallery The lower layer is chiefly composed of Dnjpetesflori- forest alongrivers that are set inlarge tracts of wooded bunda,D. paruifolla,and Veprisheterophyl Emergents savanna. such as Antiarfs toxicaria, Ceibapentandra, Celtis One body of researchers says that much of the sa- mildbraedii,and Nesogordoniapapavejfera also exist vanna is maintained by fire and terms it "derived -Theecology of a forest on an inselberg differs from savanna." They argue that, if burning ceased, the rain that of the rain forest because inseLberg forest is forest would invade these areas, and they cite evi- shorter, lacks evergreen tree species, and has a poor dence of remnant humid tropical forest areas in the regeneration rate from seed. The agricultural pattem. savanna and the existence of fire-tolerant and fire- is similar to that elsewhere in the land cover class. resistant trees to support this hypothesis. Another body of researchers questions this interpre- Grassland tation on the basis of the sharpness of the forest- savanna boundary and the lack of penetration of fires "Guineo-Congolian Edaphic Grassland,' which oc- into moist forests. This lends credence to the hypoth- curs on hydromorphic soils throughout the region, is esis that, before cultivation and burningin these areas, also mapped within this land cover class. White (1983) a continuum of vegetation existed from rain forest to suggests that most of these grasslands represent tran- dry savanna (Hopkins 1974;KIeay 1952;Swaine, Hall, sitions between aquatic vegetation and forest, the and Lock 1976). grasslandstructurebeingmaintainedbyannualburn- ing. Menaut (1983) considers these to be "Coastal PopulationandAgriculture Grass Savannas' in Cote dlvoire and suggests that many are fire- prodimax communities derived from Population density varies in the area covered by this forests or wooded savannas (Adjanohoun 1962). class. Where it is low, forest and woodland areas Nevertheless, trly hydromorphic grasslands rec- dominate, but in areas of greater .opulation density, ognized in COtedIvoire ("Savanes de Basse Cote" or forests are cleared extensively. M. zy large cities and "Savanes Lagunaires") occupy small tracts along a towns in the region are. situated in this class, and 76 .sliinatiungWoody B i(amssin Suib-SafiaramAfrica around them the anthropogenic impact is severe. Due zygia, Dic)lirostacltysglomerata, Hartungana adacanein- to the continued forest clearance and fuelwood de- sis,Tmrna guincensis, and Xylopiaquintasii grow very fast mandwithinthezone,thismosaicisaprincipalsource in the early successional stages in response to large of fuelwood in the region. Not only is local demand amountsofsunlight. Othercommon foresttreesatthis from within the class great, but the land cover class is stage are Ceibapentandra, Chlarophora regia, Cola nitida, probably a net exporter of fuelwood to the cities and Eiaissguinwnsis,Mangifera indica, and Steramuitragacautba. wood-deficit areas of the region as a whole. Similar agricultural systems to that described for Extensive subsistence and cash crop agriculture Sierra Leone exist throughout this mosalc, and can be occurs in the area covered by this class. Subsistence termed bush-fallowing agricultural systems. In these, agriculture is dominated by upland and swamp rice the forest regenerates in the fallowing period, allow- cultivation in Sierra Leone, Liberia, and the south of ing soil nutrient levels and structure to recover. For CBte d'Ivoire. In Guinea and the central areas of instance, in Cote d'Ivoire, the "Secteur Prdforestier' C6te d'Ivoire, the main subsistence crop is rice, al- (Monnier 1983) is part of this class; it falls entirely into though significant areas of bananas, plantains, cas- the "Zone de Iigname." In Togo, this area is very sava, and yams are grown. These latter four crops extensive,stretchingfromthecoastalplainsto8°30'N, are also typical of the mosaic in Ghana, Togo, and and falls into four agricultural zones mapped by Nigeria. Gu-Konu (1981):(a) the southern parts of the maize- The main cash crops in these forest zones are cocoa, sorghum-yam zone, (b) the bean-maize-yam zone, (c) coffee, oil palm, and rubber, often grown on extensive the cassava-maize-yam zone, and (d) the cassava- plantations owned by companies or wealthy farmers. maize zone. However, extensive peasant cultivation of these crops Similar subsistence cropping pattems exist in Benin also occurs at a much smaller scale. In Sierra Leone, and Nigeria, where the main cash crops are cocoa many riverain grasslands are important rice-growing (Liberia,Nigeria, Togo, and Sierra Leone); coffee(C6te areas, whereas in Cote dIvoire and Liberia, important d'Ivoire, Liberia,Togo, and Sierra Leone); cotton (Cote agricultural areas are fewer but produce a broader d'Ivoire, Liberia, Togo, and Sierra Leone); oil pahn range of crops. (Liberia, Nigeria, and Sierra Leone); rice (Cote -The main control on the distribution of forest re- d¶Ivoire,Liberia, and Sierra Leone);sugarcane (Liberia growth vegetation adjacent to and within the forest and Togo); and tobacco (Cote dIvoire) (Berron and zone is primarily the continual clearance and burning Vennetier 1983; Gu-Konu 1981; Nwafor 1982; von during the dry season, which is part of the local farm- Gnielinski 1972). ing systems. Clearance and burning are carried out for three reasons: to prepare fields, to promote grazing, Class 81-Mangrove and to flush game. In Sierra Leone, such areas are mapped as "Forest Mangrove swamps are common along the West Afri- Regrowth and Farmland" (Cole 1968;FAo 1981; Clarke can coast, but are particularly important in these 1966). This area was formerly closed forest but was areas: opened to timber exploitation in the nineteenth cen- tury. Since then it has been extensively cleared and * From the Casamance River in Senegal to the Rio burned to provide land for upland rice, coffee, cocoa, Nunez in Guinea, a coastal strip that includes the and oil palm cultivation (Millington 1987). extensive mangrove of the Bijag6s Islands and the The ecological communities witiin this class range Cacine, Cacheu, Corubal, and Geba rivers in from recently cleared farms to relatively mature sec- Guinea-Bissau and the Komponi river in Guinea ondary forest regrowth. Secondary forest and bush * Around Conakry in Guinea regrowth is cleared between January and April, and * In Sierra Leone, especially in the estuaries of the the wood is dried and burned just before the seasonal Scarcies, Rokel, and Jong rivers, and around rains start in May. The dominant crop, upland rice, is Sherbro Island grown in a mixed cropping system and harvested * As a senes of small isolated occurrences in Liberia from October to December. and Cote d'Ivoire The fields are sometimes used for a second year, but * In the Volta Delta in Ghana often are allowed to revert to bush after a single year's * Along the Nigerian coast, especially in the Niger cultivation. After 2 to 3 years, a dense, low thicket and Cross deltas. forms, composed of herbs, razor grass (ScleriabarteQ,) climbers, and coppicing stumps left dunng clearance These areas account for 63,814 square kdlometers, (particularly Canthium glabrffolium, Craterispermnum about 3.1 percent of the region. The largest areas are launitun,wandAusangaccropiodes).TreessuchasAlbizia in Nigeria (35,200 square -kilometers), Liberia (5,533 TIe WestAfilcat Cmst 77 square kilometers), Guinea (5,480square kilometers), Figure 9-9. NoVIProfile, Mangrove (Class 81) and Ghana (5,111square kilometers). Mangrove swamps occur only in tidal and brackish 0.6 water along the coast in places where adequate shelter from storm waves usually exists. They comunonly 0.5 occur fringing wide estuaries, in shallow creeks, and- behind islands. Mangrove is swamp forest in which a DA- dense network of tree trunks, stilt roots, and pneu- > 03 matophores usually form an impenetrable thicket. The z - J trees root directly in the mud of the tidal flats. The 0.2 canopy cover is high and mostly evergreen, generally with no ground cover. 0.1°

The mangrove forests of West Africa are dominated 0 - 1 NigerDelta, Southrn Nigeria by three genera: Avicennia,Lagunazdaria, and Rhizophora Jan Fcb Mar Apr May Jun Jul Aug Sep Oet Nov Dcc Spatial relations among the genera, however, are not always clear. Mangrove trees of the genus Avicennkn generallyoccurinlandof Rhi20phora.However, along the mately 150 millimeters, mangrove again is quite Gambia River, for instance, no obvious zonation occurs stunted (Barbosa 1970). (Giglioli and Thornton 1965),and the Niger Delta is Many of the mangrove swamps in the region have dominated by a nixture of Rizq#opwmraharisonfi, R. man- beencleared forswamp rice culti vation. This clearance gle,R. racemosa,and Avicennia gerninans. has had an important impacton woody biomass stock, In Sierra Leone, mangrove swamp zonation is as is well illustrated by Sierra Leone. Although Temne thought to be controlled by soil conditions, topogra- farmers cultivated swamp rice in northern Sierra phy, and water salinity (Cole 1968).In Sierra Leone, Leone estuaries in the nineteenth century, the main Rhizophoraracemosa is the pioneer species on silty, impetus to clear mangrove swamp vegetation for cul- fibrous soil, while on sandy soils the pioneer species tivationcame with twentieth centurycolonial penetra- areAvicenniaafricana,R mangle,and R.harrisonii Trees tion of the interior (Richards 1985; Millington 1987). at the mouths of rivers attain maximum heights of 7.5 Clearance of mangrove swamps leads to a buildup of to 10 meters, while upriver, at the limit of tidal incur- sulfuric acid to toxic levels in the thionic fluvisols of sion, they grow to 20 meters. the swamps. This acidity initially restricted rice culti- Inland from the area of pioneer trees, the open vation, but research by the West African Rice Devel- woodland changes to a dense, thicketlilceswamp for- opment Association (wARDA) in Sierra Leone on soil est cften dominated by Conocarpuserectus and Lagun- management techniques and the introduction of spe- culartaracemosa. In these areas, grasses and sedges cific rice varieties has led to the widespread use of characteristic of freshwater swamps invade to form an mangrove swamps for rice fanming. undergrowth, whereas other areas display a mixture Due to the concentration of population along the of mangrove and freshwater swamp forest tree and West African coast, pressure on mangrove swamps shrub species. can locally be very great. Pressure arises from land Mangrove productivity and biomass are very clearance for rice cultivation, from fuelwood exploita- closely correlated with mean annual rainfall. The tion, from the preferential use of mangrove wood for greatest productivity exists in humid tropical for- smoking fish and baking bread, and from its use in est areas, although they show only moderate sea- building construction. Areas of mangrove adjacent to sonality (figure 9-9). This relation can be. towns suffer severe exploitation, and in these areas illustrated using tree height as an indicator of the fuelwood supply problems undoubtedly exist, accen- growing stock In the Niger Delta, where the mean tuated by the value placed on mangrove wood be- annual rainfall is more than 4,000 millimeters, cause of its high calorific value. Rhizophoramangle stands attain 45 meters in height (Rosevear 1947). But at the northern and Land Cover Class Tables- southern limits of mangrove on the west coast of Africa, tree heights are much lower. At the north- Tables 9-9 through 9-17, beginning on page 80, pres-, ern limit on Ile Tidra, Mauritania, 19°50' N, where ent summaries for each land cover class of the area, mean annual rainfall is 100 millimeters, Avicennia showing growing stock and sustainable yield for the spp. trees are only a few meters high (Chapman West African coast nations of Benin, Ghana, Guinea- 1977). At the southem limit in Benguela, Angola, Bissau, Guinea, Cote d'Ivoire, Liberia, Nigeria, Si- 12030' S, where mean annual rainfall is approxi- erra Leone, and Togo. 78 EstirnalingWoody Biornassin Sib-SgaharanAfrica

References Giglioli, M. E. C., and I. Thornton. 1965. "The Manr- grove Swamps of Keneba, Lower Gambia River Every effort has been made to facilitate access to the Basin. L Descriptive Notes on the Climate, the documents listed here. Some documents, however, Mangrove Swamps and the Physical Composition lack full bibliographic information because it was of Their Soils." Journalof Applied Ecology2(1): 81- unavailable; also, some documents are of limited 103. circulation. Gu-Konu, Y. E. 1981a."Population." In Y. E Gu-Konu and G. Laclavere. Togo. Paris: Les Editions Jeune Adjanohoun, E. 1962. "Etude phytosociologique des Afrique. savanesde basses Cote dIvoire (savanes lagunaires)." Gu-Konu, Y.E. 1981b."Agriculture." In Y.E. Gu-Konu Vegetatio11:1-38. and G. Laclav&e. Togo. Paris: Les Editions Jeune Afolayan, A., and K M. Barbour. 1982. 'Population Afrique. Distribution and Density." In K M. Barbour, J. S. Gu-Konu, Y. E.,and C. Laclavere. 1981.Togo. Paris: Les Oguntoyinbo, J. 0. C. Onyemelukwe, and J. C. Editions Jeune Afrique. Nwafor. Nigeria in Maps. London: Hodder and Hall, J. B., and M. D. Swaine. 1976."Classification and Stoughton. Ecology of Closed-Canopy Forestin Ghana."Journal Areola, 0. 1982a. "Vegetation." In K. M. Barbour, J. of Ecology64:913-51. S. Oguntoyinbo, J. 0. C. Cnyemelukwe, and J. C. Rambler, D. J. 1964. "The Vegetation of Granite Out- Nwafor. Nigeria in Maps. London: Hodder and crops in Westem Nigeria." Journalof Ecology52(3): Stoughton. 573-94t Areola, 0. 1982b. "Land Use." In.K. M. Barbour, J. S. Hopkins, B.J. 1974 Forestand Savanna.2d ed. London: Oguntoyinbo, J. 0. C. Onyemelukwe, and J. C. Heinemann. Nwafor. Nigeria in Maps. London: Hodder and Jansen, J. W. A. 1972. "Vegetation." In S. von Stoughton. Gnielinski. Liberiain Maps. London: University of Arnaud,J.-C. 1983."Economie du bois." Atlas dela COte London Press. d'lvoire.Paris: Les Editions Jeune Afrique. Jenik, J., and J. B. Hall. 1976. "Plant Communities of Barbosa, L. A. 1970. Carta fitogeogrdficadie Angola. the Accra Plains, Ghana." FoliaGeobotanica et Phiyto- Luanda: Inst. Invest Cient. Angola. taofnomica11:163-212. Berron, H., and P. Vennetier. 1983. "Agriculture." Jones, E W. 1963. "The Forest Outliers in the Guinea Atlas de la COted'Ivoire. Paris: Les Editions Jeune Zone of Northern Nigeria." Journalof Ecology51(2): Afrique. 415-34. Bianchi, H. 1986. Assistanceau developpementforestier, Keay, RtW. J. 1952. "IsoberliniaWoodlands in Nigeria Guibn-BissawPlanificafion forestiere. Tcp/cs/4506(A). and Their Flora." Lejeunia16:17-26. Rome: FAO. Keay, K W. J. 1959. "Derived Savanna-Derived from Brookman-Amissah, 1.1987.MultipurposeMaLnagement What?"- Bulletin d'Institut Frangais d'Afrique Nord, of Woody Vegetations in the Northern Regions ofGhana. Serie A 21:427-38. Kumasi. Lawson, G. W. 1968. "Ghana." Acta Phzytogeographica Brunel, J. F. 1981. "Vegtation." IT Y. E. Gu-Konu and Suecica 54:74-76. C. Laclavere. Togo.Pads Las Editions Jeune Afrique Lecomte, G., and N. Monnier. 1983. 'Population." Atlas Chapman, V. J. (ed.) 1977. Wet Coastal Ecosystems. Am- tdela aote d'lwire. Paris: Les Editions Jeune Afrique. sterdamn Elsevier Scientific. Menaut, J. C. 1983. "The Vegetation of African Savan- Clarke, J. I. 1966. "Vegetation." Atlas' of Sierra Leone. nas." In F. Bouliere, ed., Tropical Savannas. Amster- London: Hodder & Stoughton. dam: Elsevier. Clayton, W. D. 1958. "Secondary Vegetation and the Menaut, J. C., and J. Cesar. 1979. "Structure and Pri- Transition to Savanna Near ibadan, Nigeria." Jour- mary Productivity of Lamto Savannas, Ivory Coast." -nalof Ecology 46(2): 'ZA7-38.- Ecology60(6):1197-1210. Clayton,W.D.1961. "DerivedSavannainKabbaProv- Menaut, J. C., and J. C6sar. 1982. "The Structure and ince, Nigeria" Journal of Ecology 49(3): 595-604. Dynamics of aWest African Savanna." In B.J. Hunt- Cole,N. H.A. 1968. The VegetelionofSierra Leone. Njala, ley and B.'H. Walker, eds., Ecology of Tropical Savan- Sierra Leone: Njala University College Press. nas. Berlin: Springer-Verlag- FAo (Food and Agriculture Organization of the United Millington, Andrew C. 1987. "Environmental Degra- Nations). 1981. Land Systems of Sierra Leone. FAO- dation, Soil Conservation and Agricultural Policies Government of Sierra Leone Land Resources Sur- in Sierra Leone, 1895-1984.' In David D. Anderson vey Project, Report i, Freetown. and Richard Grove, eds., Conseraion in Afria People, The West Afiican Coast 79

Policies,and Practice.Cambridge: Cambridge Uni- Swaine, M. D., J. B. Hall, and J. M. Lock. 1976. "The versity Press. Forest-Savanna Boundary in West-Central Ghana." Miilington, Andrew C., Felix Helmisch, and Gaest GhanaJournal ofScience.16:35-52. Rhebergen. 1985."Iand ValleySwamps and Bolisin Swaine, M. D., D. Lieberman, and J. B. Hall. 1990. SierraLeone:HydrologicalandPedologicalConsider- "Structure and Dynamics of a Tropical Dry Forest ations for Agricultural Development.' Zeitsdchftffr in Ghana." Vegetatfo88:31-1. Geomorphologie,Supplemnent Band 52, 201-22 von Gnielinski, S. 1972. Liberiain Maps. London: Uni- Monriier, Y. 1983. "Vdgdtation." In Atlas de la CMte versity of London i'ress. d'Ivire. Paris: Les Editions Jeune Afrique. Voorhoeve, A. G. 1968. "Liberia." Acta Phlytogeo- Morison C. G.T.,A. C. Hoyle, andJ. F. Hope-Simpson. graphicaSuecica 54:74-76. 1948. "Tropical Soil-Vegetation Catenas and Mosa- White, F. 1965."The Savanna Woodlands of the Zam- ics." Journalof Ecology36(1): 1484. bezian and Sudanian Domains. An Ecological Nwafor, J. C. 1982a. "Agrcultural Zones." In K M. and Phytogeographical Comparison." Webbia.19: Barbour, J. S. Oguntoyinbo, J. O. C. Onyemelukwe, 651-81. and J. C. Nwafor. Nigeriain Maps. LondonEHodder White, F. 1983. "The Vegetation of Africa." Natural and Stoughton. ResourcesResearch Series 20. Paris: LINESCO/AETFAT1 Nwafor, J. C. 1982b. "Major Cash Crops and Planta- uNso (United Nations Educational, Scientific and tions." In K Iv Barbour, J. S. Oguntoyinbo, J. 0. C. Cultural Organization/Associationpour ['Etude Taxo- Onyemelukwe, and J. C Nwafor. Nigeria in Maps. -nomique de-la Flore de ['Afrique Tropicale/United London: Hodder and Stoughton. Nations Sudano-Sahelian Office).

.~ . .

7. .

~~~~~~~~~~~~--. . - - ,. - . - . . , .A:. 80 EstimatinigWoody Biomnssin SUb-SaharanAfricM

Table 9-9. Land Cover Classes-Benin (West African Coast Region) Arma GrowiugRslock Sntslainableyvield -os.rliosad Th1oulsando0nies Laid coverclass ait2 Percel f-OJIIIs Prcenl per year Perceni 12 2,108 1.84 478.52 0.18 21.08 0.32 1 2,108 1.84 478.52 0.18 21.08 0.32 22 211 0.18 69.63 0.03 2.11 0.03 2 211 0.18 69.63 0.03 2.11 0.03 43 211 -018 357.01 0.13 4.43 0.07 4 211 0.18 357.01 0.13 4.43 0.07 52 211 0.18 453.65 0.17 13.29 0.20 5 211 0.18 453.65 0.17 13.29 0.20 -62 11,435 10.00 30,531.AS 11.21 880.50 13.51 64 40,839 35.70 109,040.13 40.02 1,878.59 28.82 65 14,755 12.90 39,395.85 14.46 708.24 10.86 6 67,029 58.60 178,967.43 65.69 3,467.33 53.19 74 5,849 5.11 9,849.72 3.62 111.13 1.70 76 38,046 33.26 64,069.46 23.52 722.87 11.09 7 43,895 38.37 73,919.18 27.14 834.00 12.79 81 738 0.65 18,213.84 6.68 2,176.36 33.39 8 738 0.65 18,213.84 6.68 2,17636 33.39 Total 114,403 100.00 272,459.26 100.00 6,518.61 100.00 (Percentage of region) (5.60) (5.08) (2.53) Note:In the followirgtable detailsmay not addto totalsbeuse of roundi_g. Source:Authois calculationsfrom data basesderived fromland cover classification and table4-1.

Table 9-10. Land Cover Classes-Ghana (West African Coast Region) Area G.irongstock Sustainableyield Thousand TIousand tonnes Landcover class knm Percent tonnes Percent Iper ear Percent 12 1,054 0.45 239.26 0.04 10.54 0.05 1 1,054 0.45 239.26 0.04 10.54 0.05 22 685 0.29 226.05 0.04 6.85 0.03 2 685 0.29 226.05 0.04 6.85 0.03 41 263 0.11 365.57 0.06 5.52 0.02 43 158 0.07 267.34 0.05 3.32 0.01 44 316 0.13 44.56 0.01 11.06 0.05 4 737 0.31 677.46 0.12 19.90 0.08 52 1,001 0.42 2,152.15 0.37 63.06 0.28 5 1,001 0.42 2,152.15 0.37 63.06 0.28 62 18,233 7.70 48,682.11 8.43 1,403.94 6.31 64 47,110 19.89 125,783.70 21.77 2,167.06 9.74 65 22,975 9.70 61,34325 10.62 1,;02.8D 4.95 6 88,318 37.29 235,809.06 40.81 4,673.80 21.00 74 -7,694 3.25 12,956.70 2.24 146.19 0.66 75 18,812 7.94 .31,679.41 5.48 357.43 1.61 76 99,383 41.97 167,360.97 28.97 1,88878 8.48 7 125,889 53.16 211,997.08 36.69 2,391.90 10.75 81 5,111 2.16 126,139.48 21.83 15,07234 67.71 84 53 0.02 524.70 0.09 21.04 0.09 8 5,164 2.18 126,664.18 21.92 15,093.3B 67.80 Lakes 13,964 5.90 0.00 0.00 0.00 0.00 Total 236,812 100.00 577,765.24 100.00 22,259.43 100.00 (Percentage of region) (11.59) (10.78) (8.66) Source Authors'calculations from data basesderived fromland coverclassification and table4-1. TbeWest Africas Coast 81

Table 9-11. Land Cover Classes-Guinea-Bissau (West African Coast Region) -______Arm Gro7uhigstock Susio;mablcyield -Thlousand - - ThomsandJonnies Lanndcouer class kL7:2 Percri -oionnies _ Percenit peryear Pcrcent

22 . 3,425 11.38 1,130.25 0 34.25 0.38 2 3,425 11.38 1,130.25 0.96 34.25 0.38 44 263 0.87 37.08 0.03 9.21 0.10 4 263 0.87 37.08 0.03 9.21 0.10 62 1,475 4.90 3,938.25 3.36 113.58 1.27 64 5,480 18.21 -14,631.60 12.49 252.08 2.81 65 422 1.40 1,126.74 0.96 20.26 0.23 6- 7,377 24.52 19,696.59 16.81 385.92 4.31 74 14,491 48.16 24,402.84 20.83 275.33 3.07 76 1,739 5.78 2,928.48 2.50 33.04 0.37 7 16,230 53.94 27,331.32 23.33 308.37 3.44 81 2,793 9.28 68,93124 58.85 8,236.56 91.78 8 2,793 9.28 68,931.24 58.85 8,236.56 91.78 Total 30,088 100.00 117,126.48 100.00 8,974.29 100.00 (Percentage of region) (1.47) (2.18) (3.49) Source:Authors' calculations from data basesderived fromland cover classification and table4-1.

Table 9-12. Land Cover Classes-Guinea (West African Coast Region) Area Grouing stock Sustainableyield Thousand Thousandtonizes Land coverclass k-n2 Percent tonnes Percent per year Percent 0 53 0.02 0.00 0.00 O.0) 0.00 22 5,006 2.09 1,651.98 0.25 50.06 0.21 2 5,006 2.09 1,651.98 0.25 50.06 0.21 43 632 0.26 1,069.34 0.16 13.27 0.05 44 0 0.00 0.00 0.00 0.00 0.00 45 - 0 0.00 0.00 - 0.00 0.00 0.00 4 632 0.26 1,069.34 0.16 13.27 0.05 52 1,581 0.66 3,399.15 0.52 99.60 0.41 -5 1,581 0.66 3,399.15 0.52 99.60 0.41 62 2,793 1.17 7,457.31 1.14 215.06 0.89 63 53 0.02 141.51 0.02 2.33 0.01 64 103,283 43.20 275,765.61 42.33 4,751.02 1956- 65 24,661 10.32 65,844.87 10.11 1,183.73 4.87 6 130,790 54.71 349,29.30 53.60 6,152.14 25.33 74 63,024 26.36 106,132.42- 1629 1,197.46 4.93 75 1,001 0.42 1,685.68 0.26 19.02 0.08 76 31,512 13.18 53,066.21 8.15 598.73 2.46 7 95,537 39.96 160,884.31 24.70 1,815.21 7-47 81 5,480 229 135,246.40 20.76 16,160.52 66.53 8 - 5,480 2.29 135,246.40 20.76 16,160.52 66.53 Total 239,079 100.00 651,460.48 100.00 24,290.80 100.00 (Percentage of region) (11.71) (12.15) (9A5)

Sour=cAuthors' calculaos frm data basesderived fromland cver dassificaionand table4-L 82 Esiimaling WoodyBioniass in Sib-SnlmnranAfrica

Table 9-13. Land Cover Classes-COte d'Ivoire (West African Coast Region) Area -Grwiugstock Sustainableyield TIhousand Tlhousandlop nes Land coverclass kn9 Percemn lonies Percent per year Percen 22 949 0.29 313.17 0.05 9.49 0.05 23 685 0.21 226.05 0.03 6.85 0.04 2 1,634 0.50 539.22 0.08 16.34 0.09 41 105 0.03 145.95 0.02 2.21 0.01 4 105 0.03 145.95 0.02 2.21 0.01 52 1,475 0.45 3,171.25 OA6 92.92 0.49 5 1,475 0.45 3,171.25 0.46 92.92 0.49 64 16,546 5.10 44,177.82 6.41 761.12 4.03 65 43,474 13A1 116,075.58 16.83 2,086.75 11.05 6 60,020 18.51 160,253.40 23.24 2,847.87 15.08 74 59,598 18.38 100,363.03 14.55 1,132.36 6.00 75 47,584 14.68 80,131A6 11.62 904.10 4.79 76 150,023 46.28 252,638.73 36.64 2,850.44 15.10 7 257,205 79.34 433,133.22 62.81 4,886.90 25.89 81 3,741 1.15 92,327.88 13.39 11,023.21 58.44 8 3,741 1.15 92,327.88 13.39 11,023.21 58.44 Total 324,180 100.00 689,570.92 100.00 18,878.44 -100.00 (Percentage of region) (15.87) (12.86) (7.34) Source Authors'calculations from data basesderived fromland coverclassification and table4-1.

Table 9-14. Land Cover Classes-Libeda (West African Coast Region) Area Growingstock Sustainableyield Thousand Thousandtonies Landcover class km2 Percent onnes Percent peryear Percent 22 158 0.17 52.14 0.02 1.58 0.0=1 2 15B 0.17 52.14 0.02 1.58 0.01 43 263 0.28 445.00 0.15 5.52 0.03 4 263 0.28 445.00 0.15 5.52 0.03 52 2,266 2.41 4,871.90 1.68 142.76 0.78 5 2,266 2.41 4,871.90 1.68 142.76 0.78 75 24,925 26.50 - 41,973.70 14.48 473.57 2.59 76 60,494 64.31 101,871.90 35.13 1,149.39 6.30 7 85,419 90.81 143,845.60 49.61 1,622.96 8.89 81 5,R5?3 5.88 136,554.44 47.10 16,316.82 89.37 84 422 OA5 4,177.80 1.44 167.53 0.92 8 5,955 6.33 140,732.24 48.54 16,484.35 90.29 Total 94,061 100.00 289,946.87 100.00- 18,257.17 100.00 (Percentage of region) (4.61) (5.41) (7.10) SoDure:Authors' calculations fom databases derived fiom landcover clWfiQakioRAd table4-1. 77wcWest Africa: Coast 83

Table 9-15. Land Cover Classes-Nigeria (West African Coast Region) - - ~~~Arcn Growin.gstack Sstasinanbleyield - otosand TIIouisan-dlCanes Landcowvr clanss k Paen? fauna Percent per ear Percenl 0 422 0.05 0.00 0.00 0.00 0.00 12 33,461 3.80 7595.65 0.31 334.61 0.24 1 33,461 3.80 7595.65 0.31 334.61 0.24 - 22 1,792 0.20 591.36 0.02 17.92 0.01 23 4,005 0.46 1,321.65 0.05 40.05 0.03 2 5,797 0.66 1,913.01 0.07 57.97 0.04 41 105 0.01 145.95 0.01 2.21 0.00 43 949 0.11 1,605.71 0.07 19.93 0.01 -44 161,827 18.40 22,817.61 0.95 5,663.95 4.07 4 162,881 18.52 24,569.27 1.02 5,686.08 4.08. 52 -11,909 1.35 25,604.35 1.06 750.27 0.54 5 11,909 1.35 25,604.35 1.06 750.27 0.54 62 154,134 17.53 411,537.78 17.07 11,868.32 8.52 63 2,793 0.32 7,457.31 0.31 122.89 0.09 64 153,765 17.48 410,552.55 17.03 7,073.19 5.08 65 121,252 13.79 323,742.84 13.43 5,820.10 4.18 6 431,944 49.12 1,153,290.48 47.84 24,884.50 17.87 73 790 0.09 1,330.36 0.06 15.01 0.01 74 53,064 6.03 89,359.78 3.71 1,00822 0.72 75 -7,641 0.87 12,867.44 0.53 145.18 0.10 76 132,739 15.09 223,532.48 9.27 2,522.04 1.81 7 194,234 22.09 327,090.06 1357 3,690.45 2.64 81 35,200 4.00 868,736.00 36.03 103,804.80 74.51 84 263 0.03 2,603.70 0.11 - -104.41 0.07 8 35,463 4.03 871,339.70 36.13 103,909.21 74.58 Lakes 3,320 0.38 0.00 0.00 0.00 0.00 Total 879A31 100.00 Z411,402.51 100.00 139,313.09 100.00

(Percentage of region) (43.06) (44.98) . (54.17) Source:Authors' calculations from data basesderivp' fromland coverdassirication and table4-1.

Table 9-16. Land Cover Classes-Sierra Leone (West African Coast Region) Area Crowingstock Suisfainablyield R ! lL -- - Thotlsand TZl~~~~~~~~~~~~~~outsanidtoiines Lrn!i0 kPercen Pcnt Togsa 65ndt perayear Percent 474 0.67 156.42 0.07 4.74 0.03 2 - 474 0.67 156.42 0.07 4.74 0.03 43 2,002 2.85 3,387.38 1.49 42.04 0.28 4 Z002 2.85 3,387.38 '149 42.04 0.28 52 1,475 2.10 3,171.25 1.40 92.93 0.62 5 1,475 2.10 3,171.25 1.40 92.93 0.62 64 2,793 3.97 7,457.31 -3.29 128.48 0.86 65 53 0.08 4.00 0.00 2.54 0.02 6 2,846 4.05 7,461.31 3.29 131.02 0.88 74 30,563 43.47 51,468.09 22.70 580.70 3.89 75 - 369 0.52 621.40 0.27 7.01 0.05 76 27,981 39.80 47,120.00 20.78 531.64 3.56 -7 58,913 83.79 99,209.49 43.75 1,119.35 7.50 81 4,592 6.53 113,330.56 49.98- 13,541.81 90.68 84 4 0.01. 39.60 0.02 1.59 0.01 8 4,59 6.54 113,370.16 50.00 13,543.40 90.69 Total 70,306 100.00 226,760.02 100.00 14,933.47 100.00 (Percentage of region) (3.44)-(423) (5.81) Source Authors'cakulaons fromdata basesderived from anLdcover dasfiation and table4-1. 84 EstimatingWoody Biomnassin Sub-Salmtran Africa

Table 9-17. Land Cover Classes-Togo (West African Coast Region) Area -Grouingstock Sustairtableyield Tlousand Thjousandtonnes Land covr class km2 Percent tonines Perent peryear Percent

12 1,792 3.31 406.78 0.:, 17.92 0.48 1 1,792 3.31 406.78 0.33 17.92 0.48

22 316 0.58 104.28 0.08 3.16 0.08 2 316 : 058 104.28 0.08 3.16 0.08

44 738 1.36 104.06 0.08 25.83 0.69 =4 - - 738 1.36 104.06 0.08 25.83 0.69

62 4,268 7.89 11,395.56 9.19 328.64 8.75 64 11,224 20.74 29,96&08 24.16 516.30 13.74 65 6,165 11.39 16,460.55 13.27 795.92 7.88 6 21,657 40.02 57,824.19 46.62 1,140.86 30.37

.74 8,958 16.55 15,085.27 12.16 170.20 4.53 75 1,107 2.05 1,4.19 1.50 21.03 0.56 76 18,865 34.86 31,768.66 25.61 358.44 9.54 7 28,930 53.46 48,71&12 39.27 549.67 14.63

81 685 1.27 16,905.80 13.63 2,020.07 53.76 8 685 1.27 16,905.80 13.63 z,020.07 53.76

Total 54,118 100.00 124,06323 100X00 3,757.51. 100.00

(Percentage of region) (2.65) -C231) (1.46)

Som0 Authors'calculations from data basesdenved fromland cover dasification and table4-1. The Horn of Africa, John Kirkby

This chapter presents a detailed desaiption of the event Soils are at best skeletal and completely absent mostunportantlandcoverclassesinhisregion.Help- from the two large areas of erg (mobile sand dunes) in ful figures in other chapters indude figure 3-1 (cloud the southwestern Libyan Desert and on part of the cover); figures 3-2, 3-3, and 3-4 (NMvIsummary land Egyptian frontier in the Nubian Desert Extensive. cover profiles); figure 3-5 (regional sununary map of areas of bare rock and rock debris without any soil land cover classes); figures 7-1 and 7-2 (continental formation (reg) exist in the Libyan and Nubian de- maps of growing stock and sustainableyield); and the serts, the Red Sea Hills of Sudan, inland areas of "RegionalLand Cover Class Map of EastAfrica" at the Eritrea, the Danaldl Alps, and on the northwestern end of this volume. coast of Somalia. Saline soils occur in the Danakil Helpful tables in other chapters include table 3-2 Depression of Ethiopia and on parts of the northeast- (land cover classes);.table 4-1 (data and sources for em coast of Somalia. growing stock and sustainable yield); and table 6-3 Phenological curves for the Danakil and Nubian (Horn of Africa estimated woody biomass by sum- deserts show expected low rates of activity, with fig- maryclass). ures for the Danalal being less than those for the southern-Nubian Desert Minima of -4102 (Danakil) Class O-Desert and +0.01 (Nubian) occurfromJuly to September, with maxima of +01)2 and +0.01 in March and November Occupying one-quarter of this region, with more than (Danakl), and +0106in April and December (Nubian). 1 million square kilometers, Desert is the largest of all Vegetationisvirtuallyabsent frommuch ofthe area, the land cover classes. Desertcovers a significant area particularly the Libyan Desert; nevertheless, plant of all four countries in the region-Sudan, Ethiopia, cover does exist, if ordy temporarily, in some situa- Djibouti, and SomaLia.The northern third of Sudan is tions. After rare rain episodes, and even after long almost entirely desert, and this continues into north- droughts, grasses (zzu) may bnefly flourish in nor- ernEritrea and the Danakil of Ethiopia. Virtually all of mally unvegetated areas. More substantial plants that Djlboutiisdesert,andthisareaextendsintothenorth- are adapted to desert conditions may survive in a em coastal strip of Somalia. Extensive areas of desert dormant state until rainfall occurs. occur on the eastern coast of northem Somalia, partic- White (1983)identifies semidesert conditions in the ularly in the Bad and Mudug regions. In Ethiopia, northeastern desert of Sudan. Hemming (1961)finds areas of desert occur within Ogaden and further more advanced vegetation than is generally implied patches exist on the borders with Kenya and Somalia. by the term "desert' in the coastal zone of northem Estimated growing stocrk and sustainable yield are Eritrea. Mangrove occurs in a discontinuous strip of both 0 percent of the regional resource (table 6-3). coastal swamp along parts of the Red Sea coast, for Most of the desert is below 300 meters altitude; example, a community of Avicennia and Rhizophora, indeed, extensive areas of the Danakil are below sea the latter particularly valued as fuelwood, exists for level Annualprecipitation is less than 150millimeters about 12 kilometers along the coast of Djibouti. and is extremelyvariable fromyear to year. Inparts of Farthernorth,intheRedSeacoastaldesertofSudan, the Libyan Desert of Sudan, rainfal is a very rare particularly to the north of Port Sudan, vegetation

85 86 EstimatingWoody Biomass int Sub-Saharan Africa occurs on the coast. Salt marshes have an almost com- Although the area is described as grassland, patches plete vegetation cover. Saline areas of wadis support of trees, woodland, and thicket exist on drier soils, Juncus arabicusand Taniarixmannifera and nonsaline particularly toward the margin of the class, on the areas of wadis have Acaca tortilis and Zil1aspinosa infrequently flooded zone. Bari (1968)identifies three (White 1983). flooded zones, based on frequency and duration of Inland, small areas of trees exist along the larger flooding (seasonal, frequent, and permanent). The desert wadis along terraces of the River Nile in north- area of seasonal flooding is mainly grassland. Swamp em Sudan and on sites where surface water concen- species such as Phagmites communis and Ilyparrhenia trates. Acacia, usually of low stature, occurs on such rufi dominate the frequently or permanently flooded sites. In higher areas of the Red Sea Hills, such as the areas. Trees are mainly Acaciaspecies; Acaciamellifera Karora Hills, smalL relict areas of Juniperus procera is common at up to 570 millimeters of precipitation forestoccur.IntheLlbyan Desert too, more substantial and Acada segaloccurs where precipitation is greater vegetation is associated with moister areas of higher than 570 millimeters. Where flooding is deeper or land. Elsewhere, at lower elevation, a scrubby vegeta- more frequent, trees are absent Grasses occurring tion dominated by Acacia glaucophylla (circummar- with the Acacia trees include Cymbopogonnervatus, gtinata)and A. etbaica occurs (Ban 1968). Along the Hyparrhenia anthistirioides, Schoenefeldia gracilis, River Nile, and at a number of places near the Red Sea Schuma ischaemoides,and Sorghum purpureo-sericeum coast in Sudan, irrigation schemes are associated with (White 1983). Hypanhenia rufa and Setaria.incassata much greater NDvivalues (see Class 22). are, however, the domiinant grasses (Badi1968). Fuelwood is very scarce and threatened by stock Itisprobablethatgrasslandandthicket haveacyclic browsing, particularly during sustained drought relation through time. Cultivation and burning of the (Mogbhaby,Ali, and Seed 1987),when drought stress, grass have combined to reduce the tree cover of the overgrazing, and cutting may destroy the limited Sudanese Hydromorphic Grasslands, and because wood stockl Where sand dunes migrate toward oases grassland is by far the largest component of the eco- or toward the desert margin, as in parts of Kordofan, system, fuelwood is limited. The estimated growing woody species may be overwhelned by blowing stock and sustainable yield are both 0 percent of the sand. Because herdspeople must use oases for water- regional resource. ing animals, the vegetation in these areas is at partic- ula risk from overgrazng and firewood cutting. In Class 13-Ethiopian Montane Steppe the Danakil Desert, an indication of the severe short- age of woodfueiis the widespread use of dung as fuel This class occupies 3 percent of Ethiopia, including all KCamweti1984). land above 3,500meters on both the easter and west- em plateaus. This class is notable ir. the northern area Class 12-Hydromorphic Grassland ofthe western plateau in the SimienRegion and Choke Mountains, and in the mountains overlooking the This class occupies 2 percent of the region, and exists east-facing escarpments of the Welo, lgre, and Shewa mainly in Sudan, where it constitutes more than 3 regions. In the easter plateau, the main areas are in percent of the area. Principal areas of this class lie im the Bale Mountains and Arsi Mountains. The area is southeastern Sudan, particularly in Jonglei and coincident with Von Breitenbach's "Mountain Steppe" eastern Sobat, but with discontinuous areas in El art of his'Mountin Savanna' classes (1963). Bukeyral and near the Blue Nile on the Ethiopian -L.Reterrain of these areas is high mountain and border, mainly below 500 meters. pla teau, formed on volcanic rock, with poorly devel- Almost all hydromorphic grassland in Sudan is oped skeletal soils and, in many cases, with steep, dearly within the flood region of the upper Nile, an -unstableslopes. Strong winds, cold temperatures, and area where the annual flood affects the flat terrain to frost are limiting factors in the development of vege- different extents, depending on small vanations of tation (White 1983).Environmental variables such as altitude. Terrain is everywhere extremely flat, with soil depth, protec-tion from wind, slope, and precipi- slopes of less than 1° on the infilled Quatemary lake tation are reflected in vegetation cover, but generally basin, which consists of dark cracking clays associated thebiomass and theheight of vegetation decrease with with hydromorphic soils (vertisols). The relative im- altitude. The lower limit of the Ethiopian Montane perviousness of the soils whenmoistcontributes to the Steppe hasremnants of aformerlymore extensive tree severity of flooding. Precipitaton increases from 400 cover, including Aada xiphocnpa (abyssmica),Apodytes millimeters a year in the north to 1,000millimeters in spp., -Hageniaabyssinica, Junrpenus procera, and Olea the south, and at more than 700 millmeters the soil is afiicana. These may form elfin thicket, particularly unable to absorb all the rainfalL in less-accessible places such as gorges. Most of the TheHorn of Afrca 8V landscape, however, is covered by Cyperaceae and Balanitesrmcemosa. Near the lakes of western Eibouti Graminieae. a small area is domidnated by dom palm, Hyphaene It is not clear to what extent the grass is priLmaryor thebaica. the result of repeated burning. At the highest levels, in Ethiopia, Class 21 extends between the Danakil widely spaced tussocks of Agrostis scierophylla,Carex Desert and the lower plateau steppes through the monostachya,Deschampsiacaespitosa, and Limosellaaftri.- areas of Keren,Asmera, Adigrat, Korem, Dese, Anko- vamare able to withstand high winds and cold temper- ber, and northern Hdrergd. attires. In protected sites, scattered shrubs such as Transition from desert may be gradual or sharp, Ericaarborea and Lobeliarhynchapetalum add diversity depending on edaphic conditions. Where water is to the vegetation, but an% susceptible to burni'ng, available near the surface, and in topographic situa- Browsing&burnin& grazing&and fuelwood collection tions. that enc-ourage water-gathering&such as 'wadis, have all contributed to loss of woody bioniass from well-de veloped Semidesert Wooded Grassland may this region, where the rate of tree g-rowth is very slow occur in nearly pure desert conditions. Similarly, the and virtually no fuelwood remains. Consequently, dry limit of this class may be as little as 80 millimeters estimated growing stock and sustainable yield are pfecdpitation (White 1983) on sands, although the des- negligible. ert may extend as far as the 150-millimeter isohyeL Generally, Semidesert Wooded Grassland gives way Class 21-Semidesert Wooded Grassland to denser woodland at about 250 millimeters. The rainfall.regime varies between 1 and 3 months This class is the second most extensive in the region, with s-ignificantrainfall. The phenolog shows a lim- occupying 15 percent of the area. Semidesert Wooded ited seasonal variationi, with two NOW maxima of ap- Grassland, which we will refer to generally as, semui- proximately 0.11 and 0.12 in November-December desert, is present in all four countries of this region, andi Mayt-june and N'io minidma,of 0.06 and 0.07 in and is particularly significant in Sudan and Somalia. April and September, reflecting the dual precipitation In Sudan, where this class makes up 14 percenLtof maxima. the' area, an irreguar wedge extends from Kassala Most of the class is on land below 600 meters, on on the Ethiopian frontier, broadening to the west in soils that are thin and poorly developed. On the Norther-n Darf ur. Ithas significant extensions north- edge of the Danakil Desert, they are saline, and in ward into the Libyan Desert, along larger~ wadis parts of northern Somialia, theyhave gypsumncrusts. such as El Milk and Hiwa, with outliers such as the ln western Sudan, extensive areas are developed on El'Atrun Oasis and onthigher ground that receives fixed sand dunes, although incursions of mobile more precipitation. Small, outlie rs also occuir in the dunes from the Libyan -Desert are widespread and.- winter rain areas of the Red Sea Hills, for example destroy vegetation. on the Erkowit Hils south of Port Sudlan and in the Much of the dass has longbeen useclfor grazingand Karora Hlills. White (1983) and Sudan Survey De- this has strongly influenced the grse,herbs, and partment (1954) indicate that all of the Red Sea Hills ItreeS.Because of browsing and grazing, manty of the and much of Kassala Province is "Acacia torliis- mare palatable Ancin species have been replaced by Macrun crassifolia Desert Scrub," which mustbe tram- unpalatable ones such as Acaudanubica, Cnssia acutili i, sitional to "Saheijan Savanna.". Wickens, in Ban' and Calotropis proceI he vegetation is subject to brief (1968), suggests that the Red Sea Hills were rapidly fluctuations ofprecipitation and occasionalprolonged deteriorating at that time (probably as a result of droughts. Although the plants are resilient, the corn- grazing pressure), and that subsequent droughts bined effect of drought and overraig has reduced would further stress the vegetation, the tree cover, even of valued species such as Acacia Most nondesert areas of northern Somalia and ex- senesal that normally would be protected as a source tensive areas of the Wadi Shebelle Valley of central of gum arabic. Somalia are Sahelian Semidesert Class 21 covers one- Crown cover is usually less than 10 percent (White third of Somalia. .1983) and continuous areas of taller trees are almost The nondesert area of Djibouti also is in this clasr. It entirely limited to rocky outcrops and water-receiving is particularly importantnorth of the Gulf of Tadjoura. site.s.Where rainfall is about 100 miillimeters, woodly Here, wiLthinthe savanna and associated with greater plant cover rarely exceeds 3 percent Annual grasses rainfall on Mount Coda between 1,300 and 1,80)0me- dominate and trees tend to have thin stemisand to be. ters, is a small area.(870 hectares) of Junipenus procema of limited height. hinSomalia, for example, the drier. and Bunts forest in the For&i du Day (Haauounil1984). scrub is rarely.more thkan3 meters high. Woody spe- Surrounding the forest are various forms. of woody cies such as Acacin ehienbergiana, A. laeta, A. ftOlEs, savanna, with Acacia arabica,A finva, A tortilis, and Balanites aegyptiaca, Boscia senegalensis, Commiphora 88 EstimatingWoody Bionmss in Sub-SaharanAfrica

afrcana, and Leptadeniapyrotechnica (White 1983)are south of Port Sudan, including the Tokar Delta. The more common and better developed toward the wet- Gash Delta, Khashim El Girba, and Gezira-Managli ter margin of the class, but are usually less than 5 irrigated areas clearly are included in the class. A large meters in height Sudan Survey Department (1954) complex also isassociated with the edaphic grasslands and Bari (1968)found that Acacia tortilis and MAerua of north Sobatand anisolated occurrence on the slopes cassifolia dominate in the east of Sudan and Acacia of Jebel Gurgei in Darfur. mellifera dominates in the west. Grasses such as Ecologically,the class covers a wide range of situa- Panicum turgidum dominate the more mobile, drier tions, and in some areas it reflects strong human influ- areas of dune crests, whereas Centdzrusbizlou covers ence on the landscape. In fact, in the northern half of lower, more stable sands. Sudan, almost every occurrence of Class 22 is directly The estimated growing stock is 2 percent of the related to irrigation and crop production. Monocul- regional total (139million tonnes), and estimated sus- Wmreof cotton donimates much of this area, and trees tainable yield is 5 percent of the regional. total (5.3 may be virtualy absent In contrast, trees form a con- million tonnes). Woody biomass is already grossly spicuous element of the Class 221andscape occurring overused in this class. Growth rates are low, and the in Sobat and western Ethiopia. social consequences of overuse are severe for the pas- White (1983) associates "Acacia Wooded Grass- toralists of this region. Overgrazing may lead to dune land' with precipitation between 250 and 500 milli- destabilization and to desertification. The class also is meters, but in Sudan, Class 22 also occurs in drier susceptible to deterioration during drought years, for and wetter areas. In the Nubian Desert, for example, example 1972-73 and 1984-85. pumped-water irrigation allows the development Desertification in this area has been examined in of this class in extremely dry areas, whereas in the Dibouti by Hamnrouni (1984); in Somalia by Okafo humid area of Sobat, the greater rainfall is effec- *(1987); in Sudan by Lewis and Berry (1988), by tively increased by Nile floodwater. Much of the Moghraby, Ali, and Seed (1987),and by Booth (1984); western plateau of Ethiopia receives up to 1,000 and in Ethiopia byKebbede and Jacob (1988).Human millimeters of precipitation. population may be very dense in this class, consider- A variety ofspeciesofAcaciaisassociated withClass ing the limited resource base. hn Somalia, for example, 22. In Ethiopia, Von Breitenbach (1963)identifies this t-hisclass supports 40 percent of the population in an area as "Lowland Woodland" with an upper story of environment in which cultivation is not possible, so trees of 5 to 12 meters, forming a more-or-less closed that grazing puts great stress on the trees (Kamweti canopy that is sparse enough to admit light to a thick- 1984). Hamilton and Maizels (1989) predict that, etlike lower story of shrubs of 1 to 3 meters. Charac- with increasing population, the dearance of wood- terstic treesareAcuciaamythetophylla,A ask A. rnel0Frn, land in northern Ethiopia in this class will continue A senegal,A. sieberna, A tortilis,A. rnosa,Ficus aco- Moghraby, Ali, and Seed (1987)attribute severe dete- carpa,Cassia singuaa, CombretummoLl, and Ziziphzs rioration to the northward spread of cultivation dur- abyssinica.Toward 2,000 meters and in drier condi- ing the late 1970s. tions, Euphorbiathicket8 to 12 meters high, dominated by Euphorbiaabyssinica, replaces Acaciatrees. Class 22-Acacia Wooded Grassland A range of Acaciaspp. also is characteristic of Class 22 along the Nile and Atbara; these include Acacia This class occupies approximately 2 percent of the nilotica,A. senegal,A. seyal,and A. tortilis. But in those region. It is present in smal patches on the lower areas where gravity irrigation, pump irrigation, or slopes to the north of the limestone escarpment in flush irrigation is possible (Grove 1978),the dominant northern Somalia. In Ethiopia, it occurs as numerous vegetation is cropland, particularly cotton. In such disconfinuous areas north of the western plateau in areas, woodland may be completely absent. Welega, Gojam, and Begemder, with further small Acaciaseya is associated with a mosaic of grassland patchesonthelowereasternslopes of the Eritreanhills and trees in the flood region of Sobat Locally, Acacia near Asmera. A string of small patches exists along spp. form almost impenetrable thicket, separated by the lower Awash River, almost to the border with areasofgrasslandontheannuallyfloodeddarkcrack- Djibouti. ing clays. Acyclicrelationappears to existbetween the The main area of 68,000 square kilometers is in thiicketand grassland of Cymbopogonnervatus, Hypa- Sudan, where it occurs in many environmentally con- haia anthlrkles, and Sorghum pwpuI-se= (White trasting areas of the country. Significant occurrences 1983). Areas of shallow flooding are associated with are along the Nile, conspicuously in the Libyan Desert A. seyal communities; areas of deeper flooding are and in the flood area of the south. Other stretches are associated with open grassland, particularly Setria along the White Nile, Atbara, and Khor Abu Habi incrassataLExtensive areas of swamp vegetation such tibutaries of the Nile. Two areas occur on the coast, as Cypenrspapyrus cover severely flooded areas. *IheHorn of Africa 89

Bushlandandthicket2to3metershighcoversrocky 0.10, but according to the length and precipitation outcrops and water-receivingsiteson the lowerslopes during the wet season, marked increases can occur. of Jebel Gurgei. Elsewhere on the pediment of Jebel Figure 10-1 shows an example from the Ogaden in Gurgei, Acacia melliferm,Boscia senegalensis, Combretum Ethiopia that demonstrates consistently small values. africanum, and Euphorbiacandelabrum form the princi- Deciduous bushland and thicket covers much of pal elements of the plant cover. . this class, normally in the form of dense bushland 3 to The estimated growing stock is 0.5 percent of the 5 meters high, but with scattered emergent trees to 9 regional total (20 million tonnes), and the estimated meters. Across extensive areas it is virtually impene- sustainable yield is 0.5 percent of the regional total trable because of the density of trunks and branches (770,000 tonnes). Burnin& clearance for cultivation, and thorniness of many plants. White (1983) believes and grazing pressure have severely reduced woody that, it is more appropriate to describe the' class as biomass in much of the class in Ethiopia, Sudan, and thicket than as savanna.-In rocky areas, or where more Somalia. In central areas of eastern Sudan, agriculture water is available, emergent trees may form a more- dominates the class, particularly on the cracldng clays or-less full cover with touching crowns. Toward the where Graham (1969) notes that removal of trees is west of Ogaden, the class is less thicketlike and Acacia associated with clearance for commercial agriculture. seyal is more dominant Along wadis and rivers, river- A further pressure on trees in this zone is the demand ine forestmay occur, and along the course of thejuba, for fuelwood for the three towns of Khartoum, Khar- a gallery forest about 200 meters wide once was pres- toum North, and Omdurman (LewiL and Berry 1988). ent over considerable stretches (Mooney 1959). Bally Kassas (1970) notes the progressive removal of tree (1968) notes that Hyphaene is present along both the cover southward from Khartoum (see Class 44). The Juba River and Wadi Shebelle. extension of agriculture and need for fuelwood. Again, awide range ofAacia spp. is present; White aroundrefugeesettlementshassignificantlyincreased (1983) notes thirty Acacia spp. and sixty Commiplwra the rate of tree remova in Sudan since 1970. spp. as endemic. Shrubs are short-stemmed, multi- branched, and underlie scattered umbrella-like trees Class 41-DryAcacia-Commiphora Bushlad such as Acacis nubica, A melifera, A. se negal, A. seyal, and Thicket and Commiphora boiviniana. The thicket-forming scrub is short-stemmed and multibranched (Von TIhough isolated areas of this class occur within the Brietenbach 1963). Perennial grasses occurintussodcs Semidesert Wooded Grassland (Class 21) of central between shrubs and trees, and after rainfall, bare Sudan, the main occurrence is in the souther and groundiscoveredby annualgrasses.VonBreitenbach southeastern parts of Harerge Province, southern (1963) descrIbes the class as "Shrub Steppe." Bali and Gamo-Gofa in Ethiopia, extending into the Most of thiis class is used by migrant pastoralists, larger portion of southern Somalia. Several patches many of whom travel in an annual cycle between occuronthecoastandslopesof thenortheneSomalian Somalia and the Ogaden. Bosmellia spp. is used for hifls, extending as a discontinuous line into the low- frankincense, and Commipho spp.- for myrrh, and lands of north Hareri and the Rift Valley of Ethiopia. because individual trees are owned by families, they Small areas follow the lower escarpmentin Eritrea and tend to be carefully manage i and not overused. Plan- Welo, and a large section occurs in the drer area of tations of Conocarpus spp. near Berbera, Somalia are Eastern Equatoria Province of Sudan. The class ooc- used for urban firewood (Finlayson, Child, and Van pies one-qarter of the area of Ethiopia and one-third of the area of Somalia, or 12 percent of the entire. Figure 10-L .NDv Profiles, Bushland and Thiclcet region. (Classes 41,44, and 45) Most of the class is below 1,000 meters and grades into semidesert at its drier limits. Soils are skeletal or 0.6- weakly developed. Although precipitation may be as -41 Edilopia great as 500 millimeters in southeastern Sudan and 0.5- 44Ethiopia southern Somalia, it is as slight as 200 millimeters inmA- 4Eip the Ogaden of Ethiopia and below 100 millimeters in ' northern Somalia. Evaporation is rapid and patches of 03-0 . true desert occur witiin this class in parts of the Z '/ -, * Ogaden. Precipitation varies greatly from year to year, 0.2- and prolonged drought lasting several years is dcar- acteristic of this zone.

Phenological curves show some variation in this . a , , , * , , *, class, with generally small values of approximately Jan Feb Mar Apr May Jun Jul Aug Scp Oct Nov Dcc 90 Estimaing WoodyBiomnss in Sub-SaharanAfticr

Rensburg 1972) and charcoal from this region is ex- to 5 meters tall with scattered emergent trees up to 9 ported to other parts of Ethiopia and exported from meters. (White 1983), although Mooney (1959) de- northern Somalia to Aden. These researchers found scribes the vegetation as scrub less than 3 meters high. that trees had been planted near vilages and were Acacia and Commiphoraare spiny,. so impenetrable being carefully tended, and Mooney (1959)reported a thickets may forn, particularly because many species range of planted trees near Margherita, Somalia. are multistemmed and some species of Commiphlora As nLight be expected, the pressure of grazing has havearadialprostrateform.Inthesecasesasingletree led to some deterioration of trees. Finlayson, Child,. may be 12 meters across, although less than 5 meters and Van Rensburg (1972)found that Acaciaspp. and high. Commiphoraspp. were degraded near Kisimaya, al- A few species have well-defined trunks and form though in the same area dunes were being fixed by emergents, occasionally reaching 10 meters high. Aa- planting of Commiphoraspp. This class has suffered cia tortilis, Adansoniadigitata, and Euphoia robecchii extreme degradation through overpopulation, partly are in this category, although the baobab here rarely because of the movement of refugees, and partly due exceeds 8 meters in height. -Emergenttrees are more to overgrazing. Hemming (1966)states that overgraz- common in thewetter areas, andmayevenformatype ing has occurred since the nineteenth century. The of woodland. In the Holawaiir Forest near the Kenyan most severe overgrazing is near deep boreholes, border, emergent trees reach 30 meters, with a middle around which desertification occurs. Demandcforfuel- story higher thn 10 to 15 meters. Acia busseidomi- wood increases the rate of depletionL The estimated nates large areas, with few other spemes under its growing stock is 15 percent of the regional total (729 spreading crown (Bird and Shepherd 1988). nillion tonnes). The estimated sustainable yield is 8 Most species are deciduous, although a small per- percent of the regional total (11 million tonnes). centage are evergreen, and succulents are widespread. Kamweti (1984)condcuded that fuelwood shortages in Grasses form an insignificant part of the above- Somalia are extreme. ground- biomass, although Bally (1968) notes that where stock are excluded, a much greater profusion of Class 43-MoistAcacia-Commiphora vegetation quickly develops. Acacia spp., Cappari- Bushland and Thicket -dwceaspp., Commiphomspp., and Grewiiaspp.are very -common. Toward the south of Somalia, Euphorbia This class covers 2 percent of the region, mainly to- robeeccii,which is unusual in having a straight bole, ward the coast in south Somalia (Shabeeflala Dhexe, may also form a conspicuous and taller element, al- Shabeellaha Hoose, Jubbada Dhexe, and Jubbada though it has been used extensively in box-making Hoose) atelevations of up to 200 meters, and includes because it is one of the better timber tres (Mooney thevalleys of thelowerJubaand WadiShebele.About 1959),and numbers at that tim were much reduced. . percent of Somalia is in this class. Precipitation In a narrow zone near the Juba River, a number of varies between 300 and 600 millimeters a year, with taller trees that form a type of gallery forest are re- two wet seasons. Considerable fluctuation in precipi- ported by Firlayson, Child, and Van Rensburg (1972). tation occurs from year to year, however. This forest, however, is being encroached on for both Class 43 in south Somalia is almost completely sur- permanent and shifting cultivation and has been cut rounded by Dry Acaca- C.-nmmiphora Bushland and -for commercial timber (Luhini 1986). The largest of Thicket (Class 41), with a gradual transition between LhelowerJubafoests was about l50square kdlometers the two. A number of patches also exist in southem in extent in 1948, but had been reduced to less tan Ethiopia at altitudes up to 1,500 meters. The largest 2,000 hectares in 1987, and less than 700 hectares re- area is near Ginir in the Shebelle Valley and in the main in the lower Shebelle (Douthwaite 1987).Domi- upper Geneale Valley. Other small areas are on the nant tres in the riparian Juba.forests indude Aca slopes of the southern Rift Valley and in the lower seyal,Afea quanzensis,Anidesm ?m7enosm,Mifmusops OmoValley. PreCipitationmEtiopia mayattain1,000 fruwiosa, Sorina madagascariensis,Spfrostadcys reni- miimeters, with two rainfa maxima.ll ferz, Thesia danis, and TrichrTcRemetca (Luchini Compared with Class 41, wivt -valuesare generaly 1986).Douthwaite (1987)identifies about 50,000hect- greater, although June, thfemonth with the greatest ares of forest in the Ltolawajir Depression bordering value of 0.45, is almost tre same as values frou Class Kenya,butpredicts thatatthepresentrateof clearance 41 in inland southern Somalia. Minimum mmvivalues most will have been removed by the year 2000. of 0.18 and 0.19 for March and April are, however, Speciescharacteristicof themain canopyofClass 43 considerably greater than those for Class 41. in Somalia are Aacia bussei,A horrida,A. mdlifera,A. InSomaliathelassissilartobutdenser tanthe nilotica,A. refias, A thomasi, Baamnitesorticularis, Dry Acacia-CommiphoraBushland and Thicket (Class Bosciacoriaca, Boswellianeglecta, Commiphora africana, 41). Generally, it forms a two-story dense bushand 3 C. boivinima, C campestris, Cadaba spp., Dobera spp., TiteHorn of Africa 91

Euphlrbia spp., Salvadora spp., Sterculia spp., and Ter- that even poorsources such as Commiphora were being minalia spp. (White 1983; Mooney 1959). Smaller bushes used for charcoaL Much of the tree canopy in the Bay include Bauhinia titensis, Bridelia taitensis, Cae.salpinia area east of the Juba River has been lost, causing soil trotwae,Combretumaculeaturn,Ecboliumnspp., Grewia spp., erosion and land degradation and greatly reducing Maerua spp., and Sericocomopsis spp. (White 1983; the grazing potential. Mooney 1959; Bird and Shepherd 1988). Cultivation also is increasing in the Juba Valley. The small areas of this class in the lower Omo Valley Douthwaite (1987) stresses the significance of farrning, and the Rift Valley of Ethiopia are similar to the Soma- logging, mining, and water resource development in lian area described previously, but much of the reduction of the lowland forest resource of southern Ethiopianoccurrenceof thisclassisathigher altitudes, Somalia. Uses of timber in the remaining Shebelle above 1,500 meters. Dry Acacia-CommipphoraBushland gallery forest (approximately -700 hectares) include and Thicket (Class 41) adjoins this class at lower alti- timber for beehives, charcoal, fuelwood, building tim- tudes, and.Cultivation and Forest Regrowth Mosaic ber, agricultunal implements, and goat browse. The (Class 73) lies at the same altitude to the south. Beals estimated growing stock and sustainable yield are (1968) describes Class 43 as "Deciduous Woodland about 2 percent of the regional total (118 million and Savanna," dorninatedbyAcaciawoodlanidwithA. tonnes and 1.5 nuillion.tonnes, respectively). senegal, A. seyal, and A. tortilis, locally domninated bv other Acacia spp. At higher elevations,Acraciazetbaicais Class 44 Sahel-Sudanian Acacia Wooded more common. Bushland Von Breitenbach (1963) considers the area to be part of the lowland savanna woodland with a closed can- This class, which occupies 10 percent of the region, opy at 5 to 12 meters, but allowing sufficient light to occurs in Sudan and Ethiopia. It is particularly exten- penetrate and allow development of shrubs 1 to 3 sive in Sudan, where it covers 16 percent of the coun- meters high. This forms Acaia thicket with Euphorbia try. It lies between the Semidesert Wooded Grassland thicket at higher elevations. (Class 21) to the north and Dry Sudanian Woodland Species listed by Von Breitenbach include Acacuia (Class 62) to the south. It forms a band about 500 amythetophya,A.asak,A mellitera,Aseyal,A sieberana, kilometers wide, stretching from southem Darfur A. torhlis, A. venosa, Albizia amra, Cassia singueana, through central Kordofan, White Nile, and. Blue Nile Combreturn inlle, Entadopsis abyjsinica, Eupharbia spp., provinces, and continuing into the northem part of Ficusspp., Greaniaspp., Maera angolensis, Pterolobium Eritrea. Small areas of Sahel-SudanianAcacia Wooded stelatum, and Ziziphus abyssinica. Parasites, including Bushland occur on the Red Sea coast of Sudan, and Loranthus and Viscum, are comnmon in tree crowns. isolated areas exist along the Mile and in small areas Kamweti (1984) identifies the coastal region of So- of the Libyan Desert More substantial outliers are malia as a region. of fuelwood deficit. White (1983) scattred to the south of the main belt in both Sudan describes the dass as having suffered extreme degra- and Ethiopia. dation through overgrazing, particularly intensified Values of-N.aforasiteinnorthermEthiopiaconfirm by the provision of boreholes used as watering sites, that growth activity is greater than in the Dry Acada- and by the increase in cattle allowed by the improve- Commiphora Bushland and Thicket (CLass 41). These mentof veterinaryservices. Fmlayson,Child,andVan values also reflect the double wet season with peaks Rensburg (1972) found that shifting cultivation and in May and October (figure 10-1). commercial woodcutting were reducing the remain- Most of the class lies on plains below 500 meters, ing areas of good-quality nparian woodland and that although in Ethiopia it extends to more than 1,500 sedentary agriculture in the Juba and Wadi ShebeUe meters. Precipitationrangesbetween 250 and500 mil- valleys and near Mogadishu was causing further re- limeters, and most of the area covered by this class ductioninvegetationcover. It is almostcertain that the experiences 2 months with at least 100 miimeters. effects of grazing and agriculture are significantly Soils vary significantly to the west of the Nile, where reducing the quality and quantity of tree cover in theclassisbestdeveloped. Quatemrarysanddunesup Class 43. to 40 meters high and up to 100 kilometers long, now Kamweti (1984) identifies fuelwood demand from mainly stabilized by vegetation, overlie kaolinitic Mogadishu as a cause of tree loss, extending for a days. These form the qoz landscape, which is well. considerable distance (some 20Dkilometers along nv- developed near El Obeid (Booth 1984). These sandy ers) to supply the 250,000 tonnes needed each year. soils cover about 65,000 square kilometers of Sudan Bird and Shepherd (1988) found thatAcacia busseiwas (White 1983). Acacia senegal is characteristic of this extensively exploited for charcoal used in towns, par- substrate, and may form almost pure stands. Because ticularlyMogadishu,butthatA senegal wasbecoming it is used for gum arabic production, it has been pro- important as A bussef was being overexploited, and tectedandincorporatedintheagriculturalsystem,but

- -- , -. - -. X 92 EstimatingWoody Biornss in Sub-SalsaranAfrica in the past two decades it h-s been extensively cut for. severely depleted within 5 kilometers of wells (Lewis fuelwood, and pressure on the land has led to its and Berry 1988). A similar effect has been observed in omission from the cropping cycle. Somalia in Dry Acacia-CommiphoraBushland and To the east of the Nile, the central clay plains are Thicket (Class 41). doninated by soils with significantlevels of montmo- IDesertification, reflecting both climatic fluctuations rillonite and illite (Graham 1Q69).These clays are im- and anthropogenic factors, has led to the deterioration permeable, becoming dry, dusty, and deeply cracked of extensive areas of Class 44. Grass burning and in the dry season, but muddy when weL Because of selective browsing have very considerably.altered the theimpermeabilityof thecrackingclays, watersupply tree species present. (Bari 1968). Moghraby, Ali, and forvegetationisless thaninthe qozareas. For example, Seed (1987)attribute deterioration of biomass in this Acaciasenegal needs 280 to 400 millimeters of precipi- zone to the southward migration of livestock-based tation on sandy soils, but 500 millimeters on the crack- communities. ing clays. Acacia seyal forms almost pure stands in The fuelwood potential of this class has been se- areas of 50Dmillimeters precipitation.on flat areas of verely depleted by the processes described, anrd if clay, but in depressions and along streams it occurs deterioration is to be halted, remedial action is essen- with much less precipitation (Smith 1953).Acaci tor- tial In the Ethiopian areas of Class 44, few trees now tilis ss. raddianaextends along streams into areas -with remain. Booth (1984) investigated restocldng with as little as 150 millimeters precipitation, but on flat Acacia senegal in the area of El Obeid to prev'ent clays needs about 450 millimeters. desertification. Throughout the clay plains, trees and shrubs are - The estimated growing stock is just 1.2 percent of more common along drainage channels. In this class, the regional total (59milliontonnes), butthe estimated on favorable sites, tree crowns may be almost touch- sustainable yield is 11 percent of the regional total (15 ing but usually are several crown diameters apart million tonnes).- The main tree species include Aacia astda, A. astrin- - gens,A aeta,A nilotica,A. sengal,A. sejal, A tomento, Class 45-Escarpment Wooded Thicket A. tortilis, Balanites aegyptiaca, Boscia senegalnsis, Corn- bretumcordof anmu. Commiphoraafricana, DalTrgia spp., Class 45 is most extensive in Ethiopia, particularly in Maenia crassifolia, Leptadenia pyrotechnica, Terminalia a long arc from Eritrea, following the eastern edge of spp., and Aoogeissus schimperi(White 1983;Bari 1968). the western plateau through TiLgre,Welo, and Shew-a, In general, trees are of small stature, on the order of 7 along part of the Rift Valley floor, along the upper to 10 meters. Grass species are mainly annuals such as escarpment of Ch'erch'er and the Harer Hills. Small Cenchrus bij7orus,but perennials become more com- relict patches exist in Shewa, Begemder, and Gojam mon in wetter areas. and in small areas in Bora. The Hirer escarpment The zone is identified by Berry (1983) as suffering section continues into northern Somalia on the high severe deforestation because of both direct and indi- north-facing escarpment, inmdudingDaloh Forest In redt physical effects of severe drought, such as that .Djibouti, a small patch of 870 hectres persists in the between 1968 and 1973. Drought in itself stresses the Foret du Day. Sudan has areas in the Boma, Didinga, trees, and, when other vegetation is lacking, herders and Dongotona hills of Equatoria, and a small relict cut much more fodder from the trees than normaL area in the Karora hills on the Red Sea coast. Fuelwood collecton for urban areas, particularly for Almest aLlof the areas covered are relatively high; the three towns of Khartoum, Omdurman, and Khar- for example, the Daloh Forest at 2,000 meters is atop a toumNorth, had extended to theEthiopian frontierby 500-meter vertical limestone scarp. In Ethiopia on the 1960. By 1980, fuelwood was being transported from east-facing scarp, Junipen's woodland occurs to 3,200 more than 600 kldometers south. Much of this fuel- meters, although in DThboutithe Fort du Day on wood is from the Sahelian-Sudanian zone. Mount Goda is only between 1,300 and 1,800 meters Kassas (1970) records that Acacia spp trees were (Hamrouni1984). Precipitationis approximately 1,000 common near Khartoum in 1955,but that by 1972 the to 1,500millimeters in Ethiopia, although exampJes of nearest trees were 90 kilometers south of the city. Juniperusexist as emergents in scrub forest with only Graham (1969)identifies agricultural andpastoral in- 650 millimeters of rainfall (White 1983). In the Daloh tensificationas an importantcause ofwood lossin this and Day forests, precipitation is much less, about 700 zone. On the clay areas, mechanized farming has en- mnillimetersin the former and 350 millimeters in the tailed complete removal of trees. In the qoz sands, latter. Both examples owe their existence to occult digging of high-yield tube wells since the early 1960s precipitationthatcreateshighhumidities fora consid- has concentrated grazing pressure around them. By erable part of the year (Hamrouni 1984; Hemming 1962,little vegetation remained within 2 kilometers of 1966). Values of NDvi,however, generally reflect the these wells-a piosphere-and vegetation had been double rainy season and, in the case of an Ethiopian T-heHorn of Africa 93 example from the rift escarpment, exhibit apeak value million tonnes). It seems unlikely that accessible greater than 0.4 in May (figure 10-1). lunipenesspp. and Podocarpusspp. will survive degra- Though the class is identified as Woodland Thicket dation by grazing, agriculture, lumbering, and cutting in its climax state, above 2,000 meters much of it for fuelwood, but Acaciaspp. too are suffering from originally was forest. IJnipents procera formed im- the same pressures in this class.Our impression is that pressive, almost pure stands up to 3,200 meters the rate of loss significantly exceeds sustainable yield. (Rochetti 1961), whereas Podocarpusgracilioroccurred The natural regeneration of Juniperusprocera appears in damper areas at about 2,000 meters. In such forests, to need particular conditions that are unlikely to be bothJuniperus spp. and Podocatpusspp.form an upper met in extensively used forest, so the present genera- evergreen story 40 to 50 meters high, with an under- tion of trees may-be the last to survive.. story of Apodytesdimidiata var. acutifolia,Cuissonia spp., and Ekebergiaspp. at 10 to 20 meters, plus a lower Ciasl 52-East African Low Woody Biomass shrub layer. Epiphytes and lianes may be present. Mosdic Junipenesprocerais light-demanding, and White (1983) suggests that, because it does not regenerate in its own Covering 3 percent of the region is this class. It is shade, it probablv depends on fire (either natural or particularly extensive in Ethiopia, where it covers anthropogenic) for its survival. about 5 percent-ofthe country. Scattered patches occur In the Forat du Day, Torcdonanthuscamphoratms in in southern Somalia, but the main areas of this class more open forest follows the degradation of Junperus are in the hills of northem Harerge and on hilly areas spp., and Acaciaetbaica, A. seyal,and A. tortilissucceed of the Gamt-Gofa and Sidamo provinces in south- as more open woodland. In Daloh Forest, Junipenms western Ethiopia. Other areas exist on the edge of the procera forms a relatively open forest with widely lava plateau of Welo Province. A discontinuous zone branch. -4 crowns. Associated with Jiniperus is a bush occurs on the lower slope of the mountains of Eastern. vegetation of Buxus lildebrandftiiCadia purpurea,and Equatoria and in the northernarea ofWestern Equato- Dodonaeaviscosa. Iniandjutnipenis forest is replaced by dia between Dry c lAdanianWoodland (Class 62) and Acaciaascrub(Hemming 1968).On the lower partof the Moist Sudanian Woodland (Class 65). escarpment, Buxus spp., Boswilia cariert Dracena schi- In Sudan, the dass occurs at about 600 meters alti- zantha,and Superbiagrndisform an evergreenscrub, and tude,butin Ethiopiaitoccurs above 2,000meters. Soils lower still is a zone of Acacid-Corimiphorascrub. In Soma- associated with this class are extremely varied, indud- lia, Hemming (1966)identifies tree types of juniper ing those of the lava plateaus and the lateritic soils of forest-closed, open degraded, and climatic relicts.. southern Sudan. Rainfall exceeds 500 millimeters, apm Throughout the class, the Juniperusand Podocarpus proaching 1,000 nillimeters in western Harerg2, and woodland is rapidly declining, partly through com- the dry season lasts between 5 and 7 months. The mercial exploitation of timber, partly through over- pattem of NDv increases to 0.27in May and June, withl grazing, and partly through a failure to regenerate. On a second slight increase to 0.15 in October, but for the the scarp between DireDawa and Hirer, considerable remaining 9 months of the year, values are as small as areahad been deared for agriculture by 1988.Much of 0.11 and 0.14. the central Ethiopian plateau may have had this type The EastAfrican Low Woody Biomass Mosaic is an of woodland; for example, it was common near Addis intermediate zone between Acacia-CommiptboraBush- Ababa at the end of the nineteenth century, but very land and Thicket (Classes 41 and 43) and Escarpment little remains, apart from that which is protected. Wooded Thicket (Class 45). It is far from uniform in Much of the deforestation occurred in the nineteenth structure or constituents, and may be either floristi- century, when timber was used for buding and as fuel cally rich or relatively poor. Certain species are almost for towns on the plateauLThe Emperor Menhlik encour- always present (White 1983):Acokant hera spp., Car;ssa aged the planting of Eualptus spp., particularly Euca- edulis,Dodonaea viscosa, Eudtea spp., Oleaafricana, San- hyptusgiobus as a replacement, so that Eualdyptus spp. are semierna spp., Tarchonanthits canmphoratus,and Teclea probably the most important trees in Ethiopia today. spp. Succulent species of Aloeand Euphorbiaare nor- Approximately 15,000hectares of Eucalyptusspp. plan- mallypresent The canopy is fairlylow, between3 and tation exist around Addis Ababa, but many small 7 meters being common, but emergents such as Eu- dlumpsalsoexistinShewa, andthetreehasbeenplanted phorbiacandelabrum may rise to 10 meters, and toward widely as a road margin plant for use as fuel and poles. the upper limit tall trees such as Juniperus procemstart Scattered blocks of Eucalyptus spp. elsewhere cover to appear. 20,000to 25,000hectares (FAO 1963). In Somalia, dominant species include Acokanthzera The estimated growing stock is IA percent of the schimperi,Buxus hildebrandtii(which may form scrub regional total (69 million tonnes) and the estimated forest), Cadia purpurea, and Dodonaeaviscosa. Other sustainableyield is 0.6 percent of the regional total (0-7 important species indude Aloeeminens, Barbeya oloides, 94 EstimatingWoody Biomanss in Siub-Salnara;, Africa

GCssoniaholstii, Dracae,aa sciizant ha,Euphorbia grandis, properties and have a profound influence on drainage and Sideroxiylonspp. (White 1983). A narrow zone of conditions and soils, and thus on vegetation. this class lies.below the Junipenrsforest of the escarp- Toward the west, the dominant cover is "Combrehinm ment in northern Somalia (Hemming 1966). cordofanutn-Dazbergiaspp., Albizia seicoceplmlaWood- Grazing, fuelwood collection, charcoal produc- land" and "Anogeissts-Combretutnhartmannian utr Wood- tion, and clearance for agriculture have reduced the land.' In the east, "Acacia mellifermThomland' and fuelwood poterntial of this class. In the Harer region, "Acaciaseyal-BalanitesSavanna" are the most import- clearance for agriculture. has been the main influ- ant formations, the former on clays, the latter on sands. ence on woody biomass, and extensive areas now In both formations, woodland alternates with patches have a low tree density and are almost entirely of grassland (Sudan Survey Department 1954). An- cropped. Roadside trees are common; these are ogeissusleiocarpus may occur in pure stands on thicker often Eucalyptus spp., which also occur in small soils in Darfur, whereas stony ground is dominated by plantations and farms. In Ethiopia, the class covers Boswelliapapynfera(White 1983).On flooded soils near a complex mosaic of land uses, with, for example, the White and BlueNiles, Acaciaastringens, A. nilotica, extensive coffee production and remnants of A. subalat, A. seyal,and A. tomentosaare comLmon. Podocarpusforest The estimated growing stock is 4 Much of the woodland that had continuously cov- percent of the regional total (230 million tonnes), ered extensive areas has been cleared for agriculture, and the estimated sustainable yield is 5 percent of particularly in central, eastem, and western Sudan. the regional total (6 million tonnes). and inEthiopia, because the treeswere easily removed with simple equipment. Pastoralism is widespread in Class .62-Dry Sudanian Woodland. the south and west, which are free of tsetse; overgraz- ing and. browsing has almost everywhere led to thin- Of the total area of the region, 9 percent is in this class. ning of the tree cover. Extensive smallholder cultiva- It is particularly important in Sudan, with more than tion occurs in Darfur and throughout Ethiopia (Berry, 330,000square kilometers. The class forms abeltup to Taurus, and Ford 1980). .500 kilometers wide in south-central Sudan, south of In the past, vegetation was allowed to recover as about 8 N and between Sahel-Sudanian Acacia part of a bush-fallow cycle. More recently, cultivation Wooded Bushland (Class 44) and Sudanian Isoberlinia has become almost continuous. The effect of agrcul- savannaandSudanianWoodland(Class64).Southern ture and grazing has been to degrade the woodland,. Darfur, Southern Kordofan, and parts of Jonglei also which on the slopes of Jebel Marra, for example, is are included in this zone. replaced by shrub or thicket Above 1,800 meters, the Dry SudanianWoodland almostsurrounds the Nile upper plains and peaks are now covered by montane floodzone, butpartoftheclassis wiffiin thesoutheast- grassland, swept annually by fire. This is almost cer- em part of the flood zone. This class covers 15 percent tainly a fire-climax vegetation, although relict trees of the surface of Sudan. Extensive areas of the northern remain. Ripanan forest remains in inaccessible gorges section of the Ethiopian plateau, including much of as an indication of widespread former conditions Begemder, western ilgre, Goiam, and western Welo (White 1983). are within this class, and significant expanses exist in Firewood collection for Khartoum has caused the Rift Valley. considerable reduction in forest cover in Eastern In Sudan, precipitation is between 500 and 800 mil- Kordofan and Blue Nile (Lewis and Berry 1988).Fuel- limeters; in Ethiopia, up to 1,000 millimeters. Gener- wood collection has severely depleted woodland in ally, areas of this class in Sudan lack pronounced relief Ethiopia around all towns, but particularly Asmera and lie below 500 meters, but in Jebel Marra the land (deforestationandovergrazingareprobablymorein- *rises to 3,057 meters. In Ethiopia, much of the class portant in this part of Ethiopia than elsewhere in the occurs on land exceeding 2,500meters, and the topog- country). raphy is more pronounce& The Precambrian Base- As a result of these pressures, the landscape has ment Complex and Nubian (Cretaceous) sedimentary changed from mainly woodland with some grassland rocksunderliemuchof theSudanese section, although to parkland or very thinly wooded farmland, and in Jebel Marra, Jebel Gurgei, and part of the Ethiopian some places even to extensive treeless steppe. Rocky frontier section are on Tertiary basic lavas. Much of areas, or those where water for human use is scarce, this, however, is covered by the qoz (stabilized Quater- are the only areas where relatively intact Dry Sudan- nary aeolian sands) in the west, or by deep, dark, ian Woodland survives. Consequently, the estimated .impermeable cracking clays (descnibed.in the section growing stock is 23 percnt of the regional total (1,098. on Sahel-Sudanian Acacia Wooded Bushland, Class million tomnes),and the estimated sustainable yield is 44). These sands and clays are vastly different in their 23 percent of the regional total (31.7million tonnes). TheHorn of Africa 95

It is almostcertain that rates of wood depletion'now into "ComlrnetumThicket," "CrotonThicket," and exceed the sustainable yield of this class and thiat "Balanifes Thicket." fuelwoodshortage will became an even more serious. As in much of the Sudaneseand Ethiopian wood- cause of envirornmentaldeterioration arid of human land', clearancefor. agriculture and collection of fire- suffering, wood has considerablyreduced the woody biomass stock of this class. Currently, the estimated growing Class 63-Sudan-Ethiopian Woodland stock is 5 percent of the regional total (259 million and Thicket tonnies), and the estimnatedsustainable yield is 3 percent of the regionaltotal (4.3million tonnes). AO. This class, which is equally extensive in Sudan and (1963)comments that these woodlands are of value Ethiopia,occupies 2percent of the region.Most of it is for fuelwood and charcoal, but, reports aerial stir- on the edge of the centralSudan platinand the foothills veys which suggest that; bamboo stands -may be and west-facingslopes of the Ethiopian plateau. Ex- more limited than was previouslybelieved. Western tensions occur along river valleys, particularly the Sudarian areas have been severely thinned, and in Blue Nile and Atbara and their tributaries in Gojam Ethiopia, permanent cultiation doiates th area and western Welega provinces. Discontinuous excten- covered by this class. sions exist into the Blue Nile and Sobat province-sof Sudan. A small area in Bahr al Ghazal adjoinsUndif- Class 64-Sudanian Woodland ferentiatedDry Sudanian Woodland, and other areas occur in less-frequently flooded areas of the Sudd. This class covers 2 percent of the region. in Sudan, a in Sudan, most of the clas lies below 600 meters, large stretch of Sudanian Woodland extends parale but in Ethiopia large areas exist above 1,000 mtrs to the southwesternborder through El Buheyrat into. with some above 1,500meters. Precipitation-in Sudan Equatorciato the south of the flood region of the upper is about 600 to 800 millimeters and in Ethiopia. aboyut Nile..Other areas exist on mountains in. Eastern 1,000 millimeters. Both countries experience 5 or 6 Equatoria.lnElthiopia,numerouspatchesoccuronthe monthiswith more thian100 mOiimeters Of rain. Thsis east of the plata bv h atfcn sapet reflected in the phenology for this class, which shows The largest area lies to the north of AddlisAbaba. a miarked seasonality, with a major contrast betweent isolated areas occur near Akcsum.andSek'ot'a, and a thersmallINDvr,valuesof 0.08to 0.15between December small area occurs anthe Hirer Hills. The class.occurs and May and values of 0.55 and 0.56 for August and at altitudes below the Moist Sudanian Woodland September. Values of NDowexceed 0.27 from June (Class 65) in Sudan; in Ethiopia, it is above the Escarp- through November. TIhe claSSis developed on dark ment Wooded Thicket (Class 45). cracking clays in Sudan and on complex Precambrian Sudanian Woodland lies mainly above 2Z)00meters, basement rocks and Tertiary lavas in Ethiopia. with considerable area above 3,000 mretersin Ethiiopia. Von Breiternbach-(1963) includes the class in his In Sudan, however, the class mainly occurs belowv500 "'Lowland Woodland" and "Lowland Savanna" meters. Soilsdiffer too, the Ethiopian soils beingmauinly classes. It forms the central section of White's Class 25b formed on basi volcaniclavas, whereas those in Sudan (1983),which extends along virtuallythe wholeborder are formed on the edge of the ironstone plateau and are between Sudan and Ethiopia. White identifies among lateritic.For mare than 6 monfts of the year, the Sudant- the prindpal constituents.: Anogeissusleiocarpus, Balan- ian area receivesin exCessof 100 milflimetersofprip ifesaegptiacaBoswelliapapyriferaCombretumcollinum, tation each mnonth.But in Ethiopia, the dry seasn is C. hartmannianum, Commiphora ajricana, Dalbergia shorter (4 monthfsin Addis Ababa and Dea4) In both meknoxylon,Eryfhrina abyssinica and Terminalabrowvnii. areas, annuualrainfall. exceeds 1,000milimeters. Von Breitenbach (1963)identifies an upper story at 5 This class is intermetdiate between Moist Sudanian to 12 meters of mainly deciduous trees, forming an W-oodland (Class 65) arid Dry Sudanian Woodland almost completely dosed canopy, bu loing suffi- (Class 62). It is best described as "Arogeissus-Khaya- dent light for a shrub layer of 1 to 3 meters height. IsoberliniaDeciduousWoodland"in Sudan (Bani1963), Rochetti (1961)records a zone. similar to WVhites, becauseit has fewerlIsoberhiniaspp. thanthe "Sudanian extendingfrom Eritreato southemnEthiopia "le bois A IsoberliniaSavanna "proper. Trees are rarelymore than feuilles caduques"-with.an almost identical list of 15 mnetershigh and species in thecsouth of Sudan tree spedies. Like Von Breitenbach, h-owever,he also include Acacia dudgeonff, A. gourmaensis, A-ntidesma. finds extensive areas of bamboo thicket, particularly v'enosum,Faunea salignza, Lophira lanceolata, Maprou-nea Oxytnnantheraabyssinica and 0. borzii in the higher africana,Maranthes pol yandra, Monotes kerstingii,Ochna areas. He describesthe trees as quite.small with thick afzelii, 0. schweinflurfhiana,Protean madiensis, and Ter- trunks. Von Breitenbach ([963) subdivides the class minaliaglaucescens(White 1983). 96 EstimathinWmWy Biotmiss i Sid'-SalSaranAfrica

In its natural state, tree cover is extensive in this Figure 10-2. NDVI Profile, Sudanian Woodland class, but cultivation has profoundly modified much (Class 65) of Class 64 through bush fallowing in less densely populated areas and by permanentcultivation in more 0c6 densely populated areas. In some areas, trees may be - )5 - 65 Sudan completPly eliminated (White 1983).This is particu- larly true in Ethiopia, where the term "woodland" is 0.4- appropriate only in a historical sense. In Ethiopia, the woodfuel scarcity is comparable to that in Class 77 xc 0.3- (Highland Cultivation Mosaic), and the estimated growing stock is only 4 percent of the regional total D- - (259 million tonnes).Further, the estimated sustain- 01 able yield is only 3 percent of the regional total (4.3 million tonnes). - 0n , M, , A,, S -JanFb Mar Apr Mny Jan Jul Aug Sep'da Noy Dc Class 65-Moist Sudanian Woodland bach's "Mountain Savanna" category (1963),although In this region, 4 percent falls within this category, he classifiesit as "LowlandSavanna" in parts of north- which covers 6 percent of Sudan. A broad band up to em Harerge, the Rift Valley,and the southwest.Von 300kilometers wide followsthe southwestemfrontier Breitenbachidentifies Acnda abyssinica, Agauia salicifolia, of Sudan. Isolated discontinuous patches occur farther - Buddieapolystadiya, and Ofiniausambarensws as charac- east and in El Buheyrat as "islands" in the Sudd. In teristic of the more humid parts of the "Mountain Ethiopia, numerous patches occur on the central and Savanna." southwestem plateaus of Gonder and Shewa, in trib- Near Awash Station, field investigations in 1988 utary valleys of the Blue Nile and Atbara, and to the showed a mosaic of cultivation and grazing with north of Addis Ababa.Larger areas occur toward the some evidence of buming and a range of densities western boundary of the rift, and a series of Linear of crown cover of Acaciaspp. varying from approx- areas follows the foot of the: Hirer Hills near Dire imately 20 percent cover to large areas with rela- Dawa. Another area lies on the upper dipslope of the tivelyfew trees. Near the railway, trees had been cut Hkrer Hills and numerous small areas exist in the for fuel. Over extensive areas, Opuntia spp., or valleys of Ilubabor and Gamo-Gofa. prickly pear, formed the understory or was the main The main extensionof this classin Sudan is at about componentof vegetation. 500 meters above sea level on the lateriticsoils devel- Asin the caseof Dry SudanianWoodland (Class 62), oped on the ironstoneplateau. In Ethiopia,most of the human activity has severely altered climax Moist class is at considerably higher altitude, more than SudanianWoodland, particularly in the highlandareas 2,500metes in places, and mainly occurson volcanic of Ethiopia. In Sudan, both pastoralism and small- rocks having a great variety of soils.Precipitation in holder faming have reduced tree cover in the west, both cases is 1,000millimeters or greater, with a wet whereasto the southeastsmallholder farming has had seasonof 4monthsinSudanand7monthsinEthiopia. a majorinfluence(Berry, Taurus, and Ford 1980).Bush This is reflected in a phenology that reveals marked fallowinghasbeenanimportantfeatureofcultivation, seasonality and NDvivalues that exceed 0.45 at the. and has reduced biomass,favored some species,and maximum (figure10-2). probablyaltered soil conditions.When the fallowsea- IntactMoist Sudanian Woodlandrarely exceeds15 son is shortened, however, significant ecological meters in height It is taller than Dry SudanianWood- changesoccur, and tree coveris much reduced. land (Class 62), but it is identifiablemainly through Sudan Survey Departnent (1954)shows a consider- the presenceof Isoberliniaspp. whichmay locallydom- able area of Western Equatoria,which is now within inate this class. It is restricted, however, in the drier this category,as having been recently derived from northernwoodlands, where it may exist on rockyhills rainforest. Fuelwooddemand in this area of Sudan is (White 1983). Other species present include Acacia less an it is farther north becauseof the lack of urban dudgeonit, A. gourmaensis,Antidesma enosum, Faurea settlements, and the productivity of the woodland is saligna Lophiralanceolata, Maprounea afiana, Maranthes greater. Consequently, more possibility of fuelwood polyandra,and Monoteskerstngit. productionfrom this class exists thanfromother types White (1983)argues that "IsoberliniaSudanian Sa- of woodland. However, in Ethiopia, on the western vanna" is significantlydifferent in stature and flors- plateau,the classis severelydepleted. Field investiga- tics to enableits separationfrbm miombo woodland. In tions in 1988suggested, however, that a reasonable Ethiopia,much of this class falls within Von Breiten- reserve existsin the AwashStation area. -heHlan- of Africa 97

The estimated growing stock is 10 percent of the (1963) recognizesa number of associations In this regional total (468million tonnes),and the estimated class,where the upper story is composedof trees 5 to sustainableyield is 6 percent of the regionaltotal (8 12metershigh, with a thicketlikelowerstory of shrubs million tonnes). 1 to 3 meters high. Characteristicassociations Include "Aa7ciaThicket,"'CombmhrtmhMicket," "Balanits'ThIcketf" Class 73-Cultivation and Forest Regrowth and "CratonThiccet," with "Euphorbia Thicket" in drier Mosaic areas. Much of this class has, however, been profoundly Approximately3 percent of the region is in this class. modifiedby grazing, burning, and clearancefor agri- InEthliopia,where most of tis-classlies,and in Sudan, culture, so that cleared sectionsaround farmed areas this class occurs in two distinctly different environ- may be effectivelygrasslands. Less 'disturbedbush- ments. Mostof the Sudanesearea is in a strip along the land occurs at a greater distance from settlements. floodzoneoftheRiverNilesouthof120 N.InEthiopia, Field investigationsin 1988in the area between Dire the class is widespread on the lower areas of the Dawa and Awash Station showed that agriculture, plateau, between 1,000and 2,000meters above sea usingirrigation water fromstreams originatingin the level. The largest single area, however, about 1,500 Hlrergi Hills, has localiy modified the land cover square kilometers, is on the dipslope of the eastem pattern.Significantly larger trees withtrunk diameters plateau, on the slopes of mountains in Bale and up to 1 meter occur.in these better-watered areas. S5idamoprovinces. Another seriesof irregular patches Pricklypear (Opuntiaspp.) forms a common compo- of Cultivationand Forest RegrowthMosaic lies to the nent of the understoryin this area, where tree density west of the southem end of the Rift Valley. Other variesconsiderably. significant areas occur toward the west of southem Consequently,the classdescribes a mosaicof differ- Gojamand Welega.In Somalia,small areas exist in the ent types of agriculture with various stages of re- lower Juba Valley. growth vegetation.Woody biomass stock varies con- Geologically,the areas are disparate.In Sudan, the siderablyspatially, but it isestimated that the growing class occurs on the plains, dominated by cracking stock is 3 percent of the regional total (149 million dlays of Quaternary age and overlyingTertiary sedi- tomes) and the sustainable yield is estimated to be mentary strata. In Ethiopia, it exists on a variety of about 1 percent of the regional total (1.6 million extrusive volcanic rocks. Precipitationin Ethiopia is tormes). about 1,000millimeters a year, with 6 or 7 dry months, whereas in Sudan precipitationis significantlyless at Class 74-Guinean Woodland 600 to 800 nillimeters. In the latter area, however, considerablesoil moisture is availablebecause of the In this region, 2 percent lies within this class. It is water-holdingproperties of the claysand the flooding particularlyextensive in Ethiopia, where it covers 3. of the Nile. percentof the country.A considerablearea in south- The phenologicalcurve for this classshows greater em Equatoria Province of Sudan also is within this NDVI values from April to November,exceeding 0.43 class,and scatteredpatchesexistwithin the floodzone for 8 months with the exceptionof September,when of the upper Nile,including some along the river itself. the value drops to 0.36.Maximum values of 0.57and LargerareascoverpartsofwesternandhighlandEthi- 0.58 occur in May and June. During the 4-monthdry opia between ZO, and 3,000meters above sea leveL season,the NDVI value falls to 0.17. The class is particularlyimportant on the western Most areas of Cultivationand ForestRegrowth Mo- plateau, in Gojam,Welega, Shewa, and Kefa, and a saic would fall within Von Breitenbach's"Lowland smallarea occursin Welo.An almostcontinuous strip Woodland' class (1963),but parts of it, particularly follows the highest edge of the escarpment of the near the Kenyanborder and in Gamo-Gofa,fall into eastem plateau from the Harer Mountains, through his "Lowland Savanna" class. In Beal's description the Gogu Mountains, to the lower sections of the (1968),most of this class occursin the "AcaciaWood- Arsi Hills. This area also includes an outlier as far land-Savanna"zone, with AcaCiasenegal, A. seyal, and south as the hills overlookingKarsa Dek A. tortilisbeing widespread. On stonier soils,particu- Precipitationregimes in Ethiopia vary; rainfall is larly in westernEthiopia, combretaceous woodland is almosteverywhere greater than 700 millimeters,but more common, with Combretumnmolle or Terminalia approaches1,400 millimeters on the edges of the rain browniithe domiinantspecies. Also in westernEthio- forest on the southwestern plateau. The wet season pia, Oxytenantheraabyssinica bamboo may be locally lastsbetween6and 8months.In Sudan, elevationsare important lower,but precipitationis stillbetween 700and 1,000 The grasses Themedatriandra and Hyparrheniaspp. millimetersfor almost all of the area of this class.A are widespread belowthe tree layer. Von Breitenbach sample NDVI curve for southem Sudan shows the 98 EstimatingWoody Biomassin Sub-Saimran Africa marked seasonality of vegetation growth in this class lyptus spp., Euphorbiaspp., and Ficussycomorus, and in (figure 10-3). higher areas, grassland. This class does not fit easily into existing classifica- In such a varied environment, fuelwood varies in tions such as those of White (1983)or Von Breitenbach availability across a short distance. Reserves of wood (1963) in Ethiopia, although it accords with Bari's remain,andinsomecasesareobviouslyprotected.but '"High Rainfall Savanna Woodland' in S;,A'An (1968), woodfuel has become a marketed good rather than a which is characterized by Anogeissus-Khayn&negaln- free good. This, together with lopped and trimmed sis and Isoberliniaspp. Much of this ciAsssis on the trees, is certain evidence of woodfuel shortage. As ferricrete ironstone plateau of Equatoria, which is else- population increases, the remaining wood will be where occupied by the remains of Isoberliniawood- even more stressed, because it will be even more ex- land. Sudan Survey Department (1954), however, tensively used for fuel and because it is the only place shows that much of the area of this class in Equatoria where cultivation may be extended. Currently, the was recently cleared rain forest, where Colacordcfolia, estimated growing stock is 2.4 percent of the regional Erythrophleumguineense, Khaya grantdoli, Mi?ragyna total (113 million tonnes). The estimated sustainable stipulosa, and Syzygium guineense were common spe- yieldislessatlpercentof theregionaltotal(l.3million cies. This interpretation also may be valid for some tonnes). areas along the upper Nile. In Ethiopia, however, it is unlikely that the class originally would have been Class 77-Highland Cultivation Mosaic rain forest, into which it grades on the southwestern plateau. Highland Cultivation Mosaic occurs on the plateau Elsewhere, because of precipitation and altitude on areas of Ethiopia between 2,000 and 3,500 meters both the western. and eastemr plateaus, much of the. above sea level and occupies approximately 17 per- class consists of degraded and largely cleared centof Ethiopia. ImportantareasareinShewa,Gpjam, Iuniperus procera and Podocarpusgracilior woodland. Welo, Gonder, and TiLgre,with smaller extents in This has been reduced to a complex mosaic of farmed Harerge, Bale, Eritrea, Sidamo, Welega, Kefa, and land with discontinuous areas of secondary woodland flubabor. This class coincides with Von Breitenbach's and thicket The amount of wooiland remauung re- 'Mountain Savanna" (1963) and. forms substantial flects the pressure of cultivation and grazing. areas of the drier sections of White's Class 19a, "Un- OntheEthiopianplateau,moreextensivelywooded differentiated Afromontane" (1983).It lies in the area areas are common on steeper slopes, although some of "Woing Dega" (Von Breitenbach 1963), or temper- hills are almost completely denuded of trees and have ate highlands, the moderate temperatures reflecting beenreplacedbygrassland.Fieldinvestigationsonthe the effect of altitude. plateau to the west of Addis Ababa in 1988 showed a Average precipitation is between 500 and 1,000oml- complex pattern: within a short distance occurred a limeters, increasing locally to 1,400 millimeters, and a landscape of extensively wooded escarpments, par- 7-monthdryseasonexists. Valuesof Nvm idicate high tially wooded and treeless hills, parkland savanna, productivity between June and November, with a and small copses. Indeed, every variation between full peakvalue of 0.6 (figure 10-3).The mostimportant soil woodland and treeless grassland was observed. Tree types on the lava plateaus are calcareous black soils species varied greatly and included Acaca spp., Euca- with a tendency toward desiccation and leaching on flatterareas, andbetterred soils onsteeperslopes (Von Breitenbach 1963). Figure 10-3. NDviProfiles, High Woody Biomass A dominant characteristic of this class is the severe Mosaic (Casses 74 and 77) effect of deforestation sparning thousands of years m the most densely populated part of the country. Here 0.6- the effects of cultivation, grazing, and fuel collection

7405 Sudan- / \ combme to make difficult the identificationof prmary -n Et.biopia / \ . - and secondary vegetation. Little tree cover now re- 0A.- mains over large areas, although Von Breitenbach 0-3 / / \(1963) and White (1983)believe that forest and wood- a1 0°3- - / \land cover were formerly much more extensive. They -2 z / - / - R identify remnants of the former cover from Acacia 0iphocarpa (abyssinica), Apodytes dimidiata, HIagenia *0.1- uabyssinica,juniperus procea, .NuJxiaspp., Olea afiiacn, and Prunus africana in mixed woodland or from o- - single-dominants such as Hageniaabyssinica,Juniperus - Jan Feb Ma Apr May Jun Jul Aug Sep Oct Nov Dce praca, or Widdringfonia cupressoides. Tte Horn of Africa 99

White (1983) believes that the single-dominant Class 84-Montane Forest stands may depend on fire, either natural or anthro- pogenic. Von Breitenbach (1963) identifies "Grass Sa- This class covers 1 percent of the region. It occupies 3 vanna" with Cyperaceae and Gramineae and "Scrub. percent of Ethiopia. Montane Forest is almost entirely Savanna" as a more arid variant A moister "Shrub restricted to southwestemEthiopia,with the two larg-- and Tree Savanna" grades upward to an "Afro-Alpine est areas divided by the Rift Valley. The largest area is Savanna" with, for example, Lobeliarhtynchopetalum. In to the east in the Mendebo Mountains, with an outlier the same area, White (1983) describes areas of on the Gogu and Badda mountains. It has extensive afromontane bamboo dominated by impressive sections above 3,000 meters and occurs above 4,000 stands of Arundinariaalpina. meters in three areas. To the west, the other more Field investigations near Addis Ababa in 1988 re- dissected area exists in the mountavis of llubabor, vealed the complexity of landscapes of this class, with Kefa, and southern Shewa, with an outlier rising to cultivatedlanddominatingflatterareasandremnants 3,300 meters at Wallel. In Sudan, small areas occur in of a more extensive tree cover evident on some hills, the Didinga Hills and Dongotona Mountains of Nearby hills either were completely treeless or had EasternEquatona. odnlya partial tree cover. In a short distance, the land- Precipitation isbetween 1,000 and 1,500 millimeters scape encompasses treeless steppe, dense cultivation, in the west of Ethiopia, and much of the eastern area parkland savanna, small patches of farm frees, and receives more than 1,400 millimeters. In the western plantations, particularly of Eucalyptus spp. (see Class zone, only 2 months are dry, but in the east this in- 45). Eucalyptusglobus was introduced in the late nine- creases to 5 months. Values of Noviare variable for this teenth century to proviClefuel and building wood for class(figurel 4)withanOctoberpeakvalue ofnearly urban areas, particularly Addis Ababa. 0.6 The presence of trees in the landscape, however, In Von Breitenbach's classification (1963),the high- may give a false impression of the adequacy of fuel- est classes above 3,200 meters are mapped as 'Mon- wood supplies. In 1988, near Addis Ababa and in the tane Steppe," whereas most of the remainder is city itself, there were signs of a severe fuelwood prob- "Humid orSubhumnidMountainWoodlandL"Accord- lem. The indicators were extensive cutting of trees, ing to White (1983), the individual trees are usually parxzularly Eucalyptus spp.; the use of low-grade shorter than in the montane rain forests that exist at wood such as twigs for fuel; the carriage of fuelwood lower altitude. The majority of tree species are wide- acrosslongdistances; the remarkablysmallindividual spread and not distinctive to this zone. Induded are parcelsofwood andcharcoalavailable forsaleinsome Apodytes dinidiata, Halena lucida,1ex mitis, Nuxia con- streets; the fact that men were involved in fuel coliec- gesta, Ocote bullata, Podocwpusfizlcatus, P. gracilior, tion as well as women and children; and that consid- Prmnus afrima, and Rapanea melanophloeos.Hagenia erable time was spent in wood collection. Dung was abysni may form dominant stands, as may Juperus sold as fuel even in Addis Ababa, a clear indicator of procra, creating Hagenia thicket and Juniperus thicket fuel shortage. Even in the country 50 kilometers to the Von Breitenbach (1963) refers to Junipues procera westofAddisAbaba,twigsanddungwerebeingused forest 45 meters high, but in much of the forest, the as fueL upper story does not exceed 20 meters, although Eucalyptusplantations on the edge of Addis Ababa Ekebergiaspp. may reach 35 meters. On wetter sites, showed evidence of severe cutting, andfuelwas being Arundinariaalpina(bamboo) may form dense thickets. imported from at least 50 kilometers away; at this "Subalpine Forest," often festooned with lichens and distance, numerous coppiced plantations exist The high price'of a donkey load of small branches (5 bin) Figure 10-4. NDVI Profile, Montane Forest (Class 84) implied a severe fuel shortage: in companson, the same load in Dire Dawa on the edge of the desert 0.6- would cost only 3 birr, confirming Kamweti's sugges- 84 Ethicoa tian (1984) that fuelwood shortage is most severe in 0.5- the highlands. Historically, this has been a region of severe fuel- 0.4 wood shortage and there is everyreason to expect that 03/ the shortage will become worse- Kamweti (1984) Z writes of "a worsening energy balance"' in the area of 02- this class. The estimated growhig stock is still 7.5 percent of the regional total (350 million tonnes), how- °- ever, and the estimated sustainable yield is 3 percent of the regional total (3.9 million tonnes). Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dcc 100 EslittiatitngWoody Bionaasshi Sub-Sahmran Africa mosses, occurs in the highest areas (Beals 1968)."Side- Beals, E. W. 1968. "Ethiopia." In 1. Hedberg and 0. roxylon Forest," with a dense canopy 10 to 20 meters Hedberg, eds., "Conservation of Vegetation in Af- high and "GalinieraForest" 10 to 15 meters high may rica South of the Sahara." Acta Phytogeographica be precursors to, ordegradedforms of,Juniperusforest Suecica54:137-39. (Von Breitenbach 1963).After fires, floristically mnixed Berry, L 1983. East Africa Country Profile-Sudan. Pro- stands may be replaced by almost pure stands of gramme for International Development Worcester, Juniperus procera,Hagenia abyssinica, or Widdrinlgtonia Mass.: Clark University. cupressoides(White 1983). Berry, 1, T. Taurus, and R. Ford. 1980. East Africa Much of the natural forest in this class has been CountryProfiles.ProgramforInternationalDevelop- removed during the past century with the extension ment. Worcester, Mass.: Clark University. of agriculture, andconsiderableareasare now used for Bird, N. M., and G. Shepherd. 198B.Charcoal in Somalia: coffee plantations. This is particularly true of the west- A Woodfuel Inventory in the Bay Region of Somalia. em plateau of Ethiopia, where virtually no montane London Overseas Development Administration. forestremains. Elsewhere, crops are grown within the Booth, G. A. 1984. Assessment of Restockingof the Gum remnants of the forest. Tumber extraction for commer- Beltfor DesertificationControl. PhaseI. Rome: rAO. cial purposes has led to the removal of a wide range Douthwaite, R. J. 1987. "Lowland Forest Resources of the larger trees. Of those previously mentioned, and Their Conservation in Southern Somalia." En- Apodytes dimidiata, Ekebergiaspp., Juniperus procem, vironmentalConservation 14(1):29-35. .and Hagenia abyssinicaare used for sawn timber and .Fo. 1963.Forest Resource Reportfor Ethiopia.Rome FAO. plywood (FAo 1963). Firilayson,W.,G. S. Child, andj.J. VanRensburg. 1972. Removal of timber commercially, or during land Forestry and Wild)ifeDevelopment Survey Mission, 12 clearance for agriculture, has greatly reduced the fuel- June 1972-10 July 1972. Sonalia. Rome: FAO. wood potential of this zone. This is one of the areas of Graham, A. 1969. "Man-Water Relations in East Cen- Ethiopia where Kamweti (1984) concludes that, as- tral Sudan!' In NL F. Thomas and G- W. Whit- suinnig suitable access, fuelwood supplies should be tington, eds., Environment and Land Use in Africa. adequate to the end of the century, although that isnot London: Methuen. very long. At the present time the estimated growing Grove, A. T. 1978. Aficat Oxford: Oxford Uraversity stock is 7.6 percent of the regional total (356 million Press. tonnes), and the estimated sustainable yield is 2.8 Hamilton, P., and J. Maizels. 1989. "Introducing Flow percent of the regional total (14.9 million tonnes). Charts to Forecast Famine.' GeographicalMagazine 61(7)34. Land Cover Class Tables Hamrouni, A. E. 1984 Rapport au gouvernement de la Rdpublqupede Djflbuti sur le ddveloppementforestieret Tables 10-1 through 10-4,beginning on page 102, pres- la lutte contrela d&rtficcatron.Rome FAo. ent summaries for each land cover class of the area, Hemming, CF. 1961."The Ecology of the Coastal Area showing growing stock and sustainable yield for the of Northern Eritrea." Journalof Ecodlogy4955-78. Hom of Africa nations of Djibouti, Ethiopia, Somalia, Hemming, C R. 1966. "The Vegetation of the Northem and Sudan. Region of the Somali Republic." Proceedingsof the LinnaeanSociety of London177(2):173-250. References Hemming, C F. 1968. "Northern Somalia." In I. Hedberg and 0. Hedberg, eds, "Conservation of Every effort has been made to facilitate access to the Vegetation in Afnca South of the Sahara." Acta documents listed here. Some documents, however, lack PhytogeographicaSuecica 54t142-45. full bibliographic information because it was unavail- Kamweti, D. M. 1984. Fuelwoodin EasternAfica: Pres- able; also, some documents are of limited cuAatiLon. ent Situation and Future Prospects.Rome: FAo. Kassas, NC 1970. "Desertification Versus Potential for Bally, P. K. 1968. "Somali Republic South." In I. Recovery in Ciircum-Sahan Territories." In H E. Hedberg and 0. Hedberg, eds. "Conservation of Dregne, ed., Arid lands in Transition. Washington: Vegetation in Africa South of the Sahara." Acta Phy- American Institute for the Advancement of Science. togeographicaSuecica 54f145-47. -Kebbede, G., and M. J. Jacob. 1988. 'Drought, Famine Bari, E. A. 1968. "Sudan." In L Hedberg and 0. andthePoliticalEconomyofEnvironmentalDegra- Hedberv eds., "Conservation of Vegetation in Af- dation in Ethiopia." Geography73(1):65-70. rica South of the Sahara." Acda. Phytogeographica Lewis,L A., and Leonard Berry. 1988. African Environ- Suecca 54:59-" ments and Resources.Boston: Unwin Hyman. T--eHorn of Africa 101

Luchini, R 1986. "Useful Trmbers of Italian Somalia." Ethiopie. Florence, Italy: Istituto Agronomico per Worldng paper number 6, Ministry of Uvestock, For- l'Oltremare. estry, and Range, National Range Agency,Mogadishu. Smith, D. 1953. Tree Growth in Sudan. Publication 3. Moghraby, A. I., 0. M M. Al, and-M. T. Seed. 1987. Khartoum: Sudan Department of Forestry. "Desertification in Western Sudan and Strategies Sudan Survey Department. 1954. Vegetation of the for Rehabilitation." Environmental Conservation14 Anglo-Egyptian Sudan. Khartoum. (Map scale (3):227-31. 1:4,W,OOAD.) Mooney, H. F. 1959. Report on tFIeScopefor Forestry in Von Breitenbach, F. 1963. The IndigenousTrees of Ethio- Somalia.Addis Ababa British Middle East Develop- pia. Addis Ababa: Ethiopian Forestry Association. mentDivision. White, F. 1983. "The Vegetation of Africa.' Natural Okafo, 0. A. 1987. Northern Rangelands Development ResourcesResearch Series 20. Paris: UNESCO/AEMFAT- Project (NRDP). UrFN/soM/022,Forestry component, uNSo (United Nations Educational, Scientific and Terminal Report. Rome:FAo. Cultural Organization/Association pour l'Etude Rochetti, G. 1961. ProbThnesde reboissementforestieret Taxononiique de la Flore de l'Afrique Tropicale/ de conservation des sols dans les pays d'otfre mer: United Nations Sudano-Sahelian Office). 102 Estimating Woody Biomassin Sub-SaiaranAfrica

Table 10-1.. Land Cover Classes-Djibouti (Horn of Africa Region) Area Growingstock Sustainableyield Thousand - llwusandtonnes Land covercass kn? Percent tonnes Percent peryear Pcrcent 0 22,132 - 6.55 0.00 0.00 0.00 0.00 21 790 3U5 260.70 100.00 7.90 100.00 2 790 3.45 260.70 100.00 7.90 100.00 Total 22,922 100.00 260.70 100.00 7.90 100.00 (Percentage of region) (0.53) (0O.D) (0.01)

Note. In the following tables, detals may not add to totals because of rounding. Saurc&Authors' cakulationsfrom data basesderived fromland coverclassification and table4-1.

Table 10-2. Land Cover ClassesEthiopia (Hoom of Africa Region) Anrn Growingstack Sustdnable yid Thousand Thusand tonnes Landlcover dkos kin? Percent tonnes Percent peryear Percent 0 134,742 11.12 0.00 O.DO 0.00 0.00 12 2,846 0.23 646.04 0.03 28.46 0.05 13 40.628 -3.35 9,222.56 0.46 406.28 0.69 1 - - 43,474 3.58 9,868.60 0.49 434.74 0.74 21 112,241 9.26 37,039.53 1.85 1,122.41 1.91 22 28,034 2.31 9,25122 0.46 280.34 0.48 23 632 0.05 208.56 0Q01 6.32 0.01 2. 140,907 11.62 46,499.31 2.33 1,409.07 2.40 41 283,342 2338 393,84.38 .19.71 5,950.18 10.13 43 5,480 0.45 9,272.16 0.46 115.08 0.20 44 31,617 2.61 4,458.00 0.22 1,106.60 1.88 45 21,552 1.78 39,892.75 2.00 452.59 0.77 4 341,991 28.22 447,468.29 22.39 7,624.45 12.98 52 60,178 4.97 129,38Z70 6.47 3,791.21 6.46 5 60,178 4.97 129,382.70 6.47 3,79121 6.46 62 48,163 -3.97 128,59521 6.43 3,70855 632 63 47,478 3.92 126,766.26 6.34 2,089.03 3.56 64 14,122 1.17 37,705.74 1.89 649.61 1.11 65 22,079 1.82 58,950.93 2.95 1,059.79 1.80 6 131,842 10.88 352,018.14 17.61 7,50698 12.78 73 63,445 5.24 106,841.38 5.35 1,205.45 2.05 74 35,095 2.90 59,099.98 2.96 666.80 1.14 77 207,936 17.16 350,164.2 1752 3,950.78 O.O 7 306,476 25.29 516,105.58 25.8 5,823.03 992 84 35,359 2.92 350,054.10 17.52 14,037.52 2331 85 6,271 0.52 80,130.84 4.01 9,281D8 15.81 86 2,002 0.17 -25,581.56 1.28 2,962.96 5.05 87 3,952 0.33 41,452.53 2.07 5,84896 9.96 8 47,584 3.94 497,219.03 24.88 32,13052 54.72 Lakes -4,690 0.39 0.00 0.00 0.00 0.00 Total 1,211,884 100.00 1,998,561.64 100.00 58,720.03 100.00 (Percentage of region) (27.88) (42.78) (42.84) Sourer:Authors' calculations from data bases derived fromland coverclassification and table4-1. ThieHorn of Africa 103

Table 10-3. Land Cover Classes-Somalia (Horn of Africa Region) Area Growtingstack Sustainableyield Thtousand Thousandtonnes Landcover closs kme Percent tonnes Percent peryear Percent 0 ~~~~~~~118,24818.65 0.00 0.00 0.0 0.00 21 212,257 33.48 70,044.81 13.30 2,122-57 23.31 22 1,475 0.23 486275 0.09 14.75 .016 25 422 0.07 139.26. 0.03 4.22 0.05 2 2-14,154 33.78 *70,670.82 13.42 2,141.54 23.52 33 685 0.11 685.00 0.13 34.25 .0.38 3 685 0.11 685.00 0.13 34.25 0.38 41 215,049 33.92 .298,918.11 56.77 4,516.03 49.50 43 64,657 10.20 .109,399.64 20.78 1,357.80 14.91. 45 5,796. 0.91 10,728.40 2.04 121.72 1.34 4 285,50 45.03 419,046.15 79.59 5,995.55 65.85 51 2,477 039 5,52.71 1.05 156.05 .1.71 52 7,641- 1.21 .16,428.15 3.12 481.38 5.29 5 10,118 1.60 21,951.86 4.17 637.43 7.00 65 4,110 0.65 10,973.70 2.08 197.28 2.17 * 6 4,110 0.65 10,973.70 2.08 197.28 2.17 73 1,054 0.17 1,774.94 0.34 20.03 0.22 * 7 1,054 0.17 1,774.94 0.34 20.0 0.22 83 158 0.02 1,402.72 or2 78.68 0.86 8 158 0.02 1,402.72 0.27 78.68 0.86 Total 634,02 100.00 526,505.19 100.00 9,104.76 100.00 (Percentage of region) (14.5)(12) (6.64) Sam= Authiors'calculations from datatbases derived fromnland coverdassification and table4-1. 104 EstimatipngWoody Biiovnass in Suib-Sriarmn Africa

Table 10-4. Land Cover Classes-Sudan (Hom of Africa Region) Area Growduigstock Sistainaiableyield 77toutsand Thjousandtontes Lantdcover class km2 Percent tonnes Percenft perilear Percent 0 840,068 33.89 0.00 0.00 0.00 0.00 12 90,478 3.65 20,538.51 0.96 904.78 1.31 1 90,478 3.65 20,538.51 0.96 904.78 1.31 21 339,463 13.70 112,022.79 5.22 3,394.63 4.90 22 66,185 2.67 21,841.05 1.02 661.85 0.96 23 316 0.01 104.28 0.00 3.16 0.00 2 405,964 16.38 133,968.12 624 4,059.64 5386 41 26,400 1.07 36,696.00 1.71 554.40 0.80 43 211 0.01 357.01 0.02 4.43 0.01 44 389,049 15.70 -54,855.91 256 13,616.72 19.67 45 9,B54 0.40 18,239.75 0.85 206.93 0.30 4 425,514 17.18 110,148.67 5.14 14,382.48 20.77 52 36,360 1.47 78,174.00 3.64 2,290.68 3.31 5 36,360 1.47 78,174.00 3.64 2,290.68 3.31 62 363,387 14.66 970,243.29 45.20 27,980.80 40-42 63 49,586 2.00 132,394.62 6.17 2,181.78 3.15 64 57,069 2.30 152,374.23 7.10 2,625.17 3.79 65 149,0;2 6.01 397,888.74 18.53 7,153.06 10.33 6 619,064 24.97 1,652,900.88 77.00 39,940.81 57.69 73 23,924 0.97 40,288.02 1.88 454.56 0.66 74- 32,144 1.30 54,130.50 2.52 610.74 0.88 7 56,068 2.27 94,418.52 4.40 1,065.30 1.54 84 685 0.03 6,781.50 0.32 271.94 0.39 85 1,370 0.06 17,505.86 0.82 2,027.60 2.93 86 843 0.03 10,771.85 0.50 1,247.64 1.80 87 2,055 0.08 21,554.90 1.00 3,041.40 4.39 8 4,953 0.20 56,614.11 2.64 6,588.58 9.52 Total 2,478,469 100.00 2,146,762.80 100.00 232.27 100.00 (Percentage of region) (57.01) (45.95) (50.51) Source:Author5' calculations from dala basesderived from land cover dassifioation and table41. CentralAfrica Terry D. Douglas

This chapter presents a detailed description of the In places the grasslands are very lightly wooded, mostimportantlandcoverclassesinthisregion. Help- with shrubby and stunted species such as Burkea ful figures in other chapters include figure 3-1 (cloud africana and Hymenocardiaacida. In Kaniama, where cover); figures 3-2, 3-3, and 3-4 (Nrvr sunmnary land the grasslands occur on the Plateau of Kasai 600 to cover profiles); figure 3-5 (regional summary map of 900 meters above sea level, the principal grasses are land cover classes); figures 7-1 and 7-2 (continental Andropagon schirensis and Hyparrhenia confinis. The maps of growingstockand sustainable yield); and the woody flora is Zambezian in affinity and very "Regional Land Cover Class Map of Central Africa" at sparse, although Acacia spp. have been reported. ihe end of this volume. Woody biomass is virtually nonexistent in this class Helpful tables in other chapters include table 3-2 and there is pressure on surrounding land cover (land cover classes); table 4- (data and sources for classes (miombo woodland, Classes 66 and 67) for growing stock and sustainable yield); and table 6-4 fuelwood. (centralAfricaestimatedwoodybiomassbysummary class). Class 25-Edaphic Wooded.Grassland

Class 11-Veld Grassland This wooded grassland class represents .1percent of the land area of central Africa, occurrng largely in This class is of only minor importance in central Af- Congo (22,922 square kilometers) with a contiguous rica, occurring only in Zaire where it covers 0.6 percent area in Gabon (6,323 square kilometers) and a few of the land area (14,017 square ldiometers).The class isolated occurrences in Zaire (1,686 square kldome- takes its name from the extensive (but floristically ters). It is just 0.04 percent of the region's growing different) grasslands of South Africa. Many Belgian stock The majority of this class occurs in one specific writers have descrbed the Zaire examples as "steppes." area between f1 S and 3S in the Plateaux Province of These are distibuted m areas along the Angola border, Congo and extending into southeastern Gabon to the most notably south of Kaananga,on interfiluvesin the east of Francevillp. Other small occurrences are im- Kasai Basin, and in the upper Kwango Basin. These mediately to the north of Brazzaville. locations lie between 6 S and ? S. Bounding these areas is Ombropbilous Humid Trop- Debate continues about the origin of these grass- ical Forest (Class 87) to the north, Seasonal Miombo lands. According to Mullenders (1954) and Devred Woodland (Class 66) to the south and west, and forest (1958),they are secondary grasslands, replacing wood- mosaics (Classes 72 and 73) to the east The class is land degraded by fires that maintain the grassland. The almost entirely restricted to the Batek6 Plateau, which dry season in these areas lasts 90 to 120 days (June to is composed of soft sandstones. The plateau surface is September) and annual rainfall ranges from 1,600 to gently undulating at about 600 to 800meters above sea 1l800millimeters. In Kwango, this class occurs on the level and is dissected by tributaries of the Zaire River, extensive Kalahari Sand-covered plateau where edaphic notably the L.finL factors are very influential The principal grasses here are A remarkable feature of this land cover class is that Ars!ida ven rystiiand EDudetizdemesi it exists in the wettest part of Congo, where annual

105 106 EstliantitngWoody Biornassin Sleb-SalwraoAfrica

Figure.11-1. NDVI Profile, Edaphic Wooded Grass- Class 62-Dry Sudanian Woodland land (Class 25) This class represents 1.6 percent of the land cover of 0.6- . .central Africa, but only 0.3 percent of the estimated - 25Congo growing stock. It occurs at the very north of Cameroon 0.s- and Central African Republic (CAR) around 10 N. In

OA- - Cameroon, it existsbetween the slopes of the Mandara Mountains and the lowlands south of Lake Chad. In a>0b3- ) / CAP,it occupies the lowland of the northern tip around Birao. It coincides with White's "Sudanian Undiffer- 0.2- entiated Woodland" dass; it is regarded as being -. 1 - .- within the Sahelian domain (Vennetier and Laclavare 1984).Within Cameroon, it covers 35,000 square kilo-

-______- meters (7.7 percent. of the land cover) and 28,000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dcc square kilometers (45 percent) incAR. The dry season is at least as long as the wet, and in northern CARit lasts from November to May. Rainfall is precipitation is between 1,800 and 2,200 millimeters, less tian 1,000millimeters a year, even in the elevated yet NDVIvalues are remarkably small for a site so near areas of northem Cameroon, and is less than 700 mili- the equator within the Guineo-Congolian zone. meters in norhenicAR. he rainfall is sufficient for cil- White's map(1983)doesnotdistinguishthisar-eafrom tivation, but is unable to support a dense vegetafion the surroundinghigherbiomass groups, althoughitis cover. For northemr CAR,KNw values are less than 0.15 particularly distinctive. from January to June, ir_easing to a little more than 0.3 Fora stationnearDjambalainthecenterof this class, inAugustandSeptember(figurell-2).Thephenological NDvivalues are consistently below 038, falling to 0.17 curves show dearly the basis on which the various in the driest month (iuly) and to 0.26 in December and Sudanian woodlands have been diferentiated. January (figure 11-1). Although the prime reasor. for This class is encroaching southward as the Sahel the low productivity of this class is the droughty na- undergoes desertification in response to cultivation, ture of the plateau soils (hence the name Edaphic grazing, and climate change. Inc,u much of this zone Wooded Grassland), regular burning has helped to has been designated a "Zone d'alarme" by the author- maintain the grassland area. ities in recognition of the desertification threat The mix of grassland and trees is varied. On the Characteristic tree species include Acaciaseyal, Com- plateau, large areas are devoid of trees or have only brefum aculeatum, and Ziziphus abyssinicz. -The thorn a thin scattering, and have been descrbed as savan- woodlandissparseandinplacesdiscontinuous,much nas. Elsewhere, on steeper valley slopes in the Lfini of it being replaced by secondary thicket. Cultivation and Mpama catchinents and along the water- inthisclassispredomninantlyofsorghumandground- courses, dense woodland and gallery forest exist. In nuts. Withincreasing population and shftng agricul- addition; small areas of forest occur on the plateau, ture, the fuelwocd resource is treatened. The esti- usually in patches of less than 1 square kilometer. The grasses grow to heights exceeding 2 meters and include Andropogonspp., Hypanrrnia spp., and Loudetia FLgure11-2. NDVIProfiles, Sudanian Woodland demensii. Many of the tree and shrub species are (Classes 62, 64, and 65) Sudarian in nature; of partiular importance are Aca- cia spp., Annona senegalensis, Hymenocardia acida, and 0.6- Khaya senegalensis.-Inthe islands of relict forest there - 62 Cennl AfricanRepublic exist Gilbertiodendrondewevrei, MMusangacecropioides, 5- 64CentrlAfrican Republic .. ' "., and other representatives of the Guineo-Congolian 4-- 65 Cen Afdcan : Domain. Republic This class coincides with scant population density, in 023- particularly in the Plateaux Province of Congo. The. Z 0.2- growing stock estimate for the region is lniflion - tonnes with a sustainable yield of 0.3 million tonnes. Near towns such as Djambala in Congo,. some pres- . sure forwoodfuel clearly exists on the stock, although . o . this is localized. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec CentraeAfrica 107 mated growing stock in CARis7S million tonnes and Estimates of growing stock are 133 million tonnes in Cameroon 93 million tonnes, with sustainable for the region and a sustainable yield of 2.3 million yields of 2.2 miUlion tonnes and 2.7 million tonnes, tonnes. respectively. Class 65-Moist Sudanian Woodland Class 64-Sudanian Woodland This is the most extensive woodland class in central This class covers just 1 percent of central Africa but Africa north of the equator and represents 9 percent of accounts for only 0.5 percent of the growing stock. It the land area of the region. The growing stock is is restricted to the northernmost fringes of the region. estimated to account for just 4.58 percent The class InCameroon, it occupies 21,974square kilometers (4.9 occurs largely within White's "Sudanian Isoberlinia percent of the area). In cAR,it occupies 27,000 square andRelatedWoodlands"class,butoverlapsthenorth- kilometers (4.5 percent of the area). It occurs as a belt em edge of the Guineo-Congolian mosaic. It occupies between the Dry Sudanian Woodland (Class 62) to the a broad latitudinal belt from 20 N to 9? N. It is by far north and the Moist Sudanian Woodland (Class 65) to the largest land cover class in CAR,covering 263,000 the south. square kilometers (42.1 percent) and is important in It falls within the class described by White (1983)as Cameroon (65,000 square kilometers, 14A percent) "Sudanian Woodland with Abundant Isoberlinia."In andnorthern Zaire (43,157square kilometers, 1.9 per- Cameroon, it occurs up to 1,800 meters altitude in the cent). In Cameroon, it impinges on the northern edge Alantika Mountains and up to 1,400 meters in the of the Mesophilous Humid Tropical Forest (Class 85). Mandara Mountains. It stretches as a belt into the In CAR, it occupies most of the central area on plateau south of Chad and thence into northemcARandsouth- surfaces between 500 and 900 meters, where it exists em Sudan. In CAR,it exists in the Sudan-Sahelian cli- alongside Guinean Woodland (Class 74). Tnnorthern matic zone to the north of Ndel, with annual rainfall Zaire, it occurs in Oubangui and Haut Uele in the of 1,000 to 1,300 millimeters. Here the topography is extreme northeastnear the Sudan border. largely below 500 meters and is developed on the This broad belt of woodland is characterzed by Quatemary deposits of the basin, which drains north- annual rainfal}s of 1,400 to 1,600 millimeters and dry ward into Lake Chad. The dry season extends from seasons usually lasting 3 to 4 months from November November to March and thus seasonality is quite pro- to at least March. The values for NDviincrease to 0.5 in nounced. For this class in eastern CAR,NDvi values are the wettest month (figure 11-2)and show smaller val- sinilar to Dry Sudanian Woodland (Cass 62) durng ues during the dry season. thedryseason,butincreasetomorethan DAinAugust As is the case with many of the Sudanian classes in and September (figure 11-2). central Africa, human activity has played an import- This class is intermediate between "Isoberlinia ant role in altering the natural Moist Sudanian Wood- Woodland" and the "Dry Sudanian Woodland" to the land, with pressure on tree cover and considerable north. It is deciduous and the woody species in CAR evidence of burning and the creation of secondary include Acaciaspp., Combretumspp., Comrniphoraspp., savanna The natural woodland often is dominated by Isobalina dok, Thayasegakensis, and Tennwlia Ia4flr Isoberlinaspp.,whichformadiscontinuouswoodland At a local scale, the vegetation may be linlked to cate- cover with a canopy 10 to 15 meters high. Other tree narypatterns(Barber,Buchanan,andGalbreath1980), species include Burkea africana,Daniellia oliveri, Er- which are dependent on the distribution of laterite, throphleumafricnum, and Monotes kersingiL floodplains, -and drainage. Cultivation has substan- Jongen and others (1960) studied an area south of tinaly modified much of this class, with tree degrada- the River Oubangui in northwestem Zaire (Bangala). tion occurring in the more populated areas. The They identified several communities at a small scale, French term for such areas is "Mosaique de Savanne with ripanan forests containing Guibourtia demeusei .Arboree, de Savanne Arbustive et de Culture." In the and U.apacaheudelotii They obseved more open wood- more elevated parts of the class in northwestern Cam- land on the sandy interfluves and yet other variants eroon, Isoberliniadoka and other typical frees of the on the laterite crusts. In this region, Isoberliniaspp. are Sudaniansectoroftenhavebeenreplacedbydomesti- rare, and many of the tree species, such as Gilber- cated tres, which include Acacia albida,Cdi ittsnterfia, tiodendroi dezexrei, are derived from the humid trop- Khaya senegalensis, and Parkia biglobosa (Ladavre ical forests to the south. 1980). In many areas, for example in western CAR,this class The fuelwood potential of this class is partly threat- contains a quite dense rural population and, although ened by the extensive cultivation within it, notably woodybiomass growing stockisestimatedtobequite sorghum with some maize, cassava, and groundauts. substantial, in some areas of greater population its 108 EstinmatinigWoody Bionaussin Sub-SalomrnAfrica sustainability may be threatened. In eastem CAR,along Figure 11-3. NDVI Profiles, Mionbo Woodland the border with Sudan, thepopulation density is much (Classes 66 and 67) lower and fuelwood depletion is not currently a prob- lem. Growing stock and sustainable yield are esti- 0.6- mated as follows: 0.5

Growvingstacrk Sustainableyicld OA- Coinlry (millionton nres) (milli lonrcs) 0.3- CAR 702 12 z Cameroon 174 30.2- Zaire (northern) 115 2 - 66Zairc 67Z2irc Class 66-Seasonal Miomnbo Woodland - M Apr J Jul . -3aneb Mar Apr May lun Ju Aug Scp Oct Nov Dcc SeasonalMiomboWoodland is themostextensive land cover class recognized in this study in central Africa. the northern edge of this class is within the Guineo- It covers 21 percent of the region and accounts for 12.4 Congolian region. Hence, trees such as MAarquesia percent of the growing stock This class exists in a macrouraare dominant to the north and Brachystegia broad belt stretching from Gabon (19,000square kilo- spp., Isoberliniaspp., and Julbenardia are dominant in meters) through southem Congo (62,000square Ilo- southernZaire. Where an understory is present, Proten meters) and across Zaire (768,square kilometers) from spp. and Uapacaspp. exist. Malaisse (1984,1985) has Bas Zaire through Kasai and Shaba. The class has been -discussed the structure of this woodland in the Shaba widely studied in Zaire (Malaisse 1978) and has been Province of Zaire near Lubumbashi. He describes a identified by Milington and Townshend (1989)in the transect at Luisnishi, 28 kilometers northeast of SADCregion from 1984 AvHRRND>Iimagery. Lubumbashi, where the tree layer attains 9 to 19 me- Because this land cover class spans such a wide area ters in height with a few dominant species reaching 22Z in central, southern, and East Africa, it does not coin- meters and, exceptionally, 29 meters. An inventory of cide with a particular climatic type, although its treespecieswithdiametersgreaterthanlOcentimeters marked seasonality is a diagnostic feature. Rainfall showed Brachystegiaspicijbnnis to be the most abun- comnmonly is between 900 and 1,300 millimeters a dant species, with. 150 individuals per hectare, fol- year, but this disguises considerable year-to-year vari- lowed by Aidia micrantia (63),Syzygiumgttineense (52), ability, which in the Lubumbashi area of southern Porinari excelsa (49), Brtchlystegia taxifolia (43), and Zaire may be as much as 700 to 1,500 millimeters twelve other species with densities of more than six (Malaisse 1978). Miombo woodlands have been di- perhectare. vided into wetter and drier types. White (1983) sepa- The SeasonalMiomnboWoodlandsarea veryimport- rated these at the 1,000-millimeter mean annual rain- ant source of fuelwood. Malaisse and Binzangi (1985) fall isohyet, whereas Chidumayo (1987) used 1,100 have considered the depletion of trees by fuelwood millimeters. gathering in Upper Shaba. For principal centers such The values of NDVI vary according to latitudinal as Lubumbashi, surrounding woodland has been position and other climatic factors. Southern Gabon clear-cut throughout a circle of radius 30 kilometers, woodlands exhibit the least seasonality in the region, and this zone is estimated to be expanding at about 1 with values between 027 and 0.5. In southern Zaire, kilometer a year. Projections indicate complete defor- the dry season is longer (May to September), with NDVI estation of more than 10,000 square kilometers sur- values reducing to 0.22, but increasing to as much as rounding Lubumbashi by the year 2050, although just 0Q57at the wet season of November to March (figure 20 percent of this area applied to forestry would be 11-3). suffiaent.to satisfy the woodfuel needs of the popula- Seasonal Miombo Woodland exeibits a structure of tion. Growing stock in this class in Zaire is 4,270 mil- spaced trees, which sometimes nearly interlock to lion tonnes, with a sustainable yield of 68 million fornmumbrellalike canopies. Where agricultural clear- tonnes. ance and burning are extensive, the woodland is often more open. The trees are deciduous in response to the Class 67-Wet Miombo Woodland marked dry-season lull in productivity. The under- growth is rarely as well developed as in savannas- The Wet MionmboWoodlands form an intermittent band Seasonal Miombo Woodlands are mainly restricted to largely to the north of the Seasonal MiomboWoodland the Zambezian phytogeographical region, although (Class 66). They occur almost entirely in Zaire where CcntralAfrici 109 they cover 268,000 square kilometers and stretch from miombo woodlands (Classes 66 and 67). Within central the Atlantic coast in Bas Zaire to the Rift Valley. This Africa it represents 5 percent of the land area and class covers 7 percent of central Africa and accounts accounts for an estimated 6.7 percent of the growing for an estimated 4.7 percent of the growing stock. It stock. It is particularly important in Congo (152 per- occurs in Kwango, on the Angolan border, and as cent, 51,000 square kilometers) and Zaire (5.3 percent, several patches throughout Kasai and Shaba on the 120,000 square kilometers);butitalso occurs in Gabon. plateau at elevations of about 1,000 meters. It also is The greatest extent of this land cover class is in central prominent on the hills near Kalermie to the west of Congo, to thenorthof Brazzaville and intheneighbor- Lake Tanganyika, where it extends over 1,500 meters ingparts of Bandundu Province in Zaire. The class also above sea level. In southern Zaire, near the border occurs in scattered pockets from central Gabon with Zambia, Wet Miombo and Seasonal Miombo eastward throughout central Zaire to Rwanda and Woodlands are intermixed on the higher plateau area Burundi. This class exists within the area mapped by to the south of Lubumbashi. White (1983) as "Guineo-Congolian Mosaic of Low- This class often occurs on light sandy soils of the land Rain Forest and Secondary Grassland." Kasai and Shaba plateaus and on the well-drained The climate of this belt is characterized by a dry soils of the hills near Lake Tanganyilka. Such edaphic season which extends for 90 to 120 days between June factorshave created anopen woodland with extensive and December (Laclav&re 1978) and has a rainfall be- grassland cover. Human interference has meant that tween 1,200 and 1,800 millimeters a year. The values woody species are under pressure, and a well-devel- of Ncvx are consistently about 0.35 in the growing oped shrub layer is rare within these woodlands. season, diminishing to 0.23 in the dry season. Wet Miombo Woodland in Zaire generaUy exists in The high woody biomass of this class results from wetter areas than the SeasonaLMiombo Woodland (Ciass being a forest remnant, secondary forest, or well- 66) and in areas where the effect of seasonality is less. wooded agricultural land with large patches of culti- Rainfallisgenerally1,000tol,Y0Dmillimetersayearand vation. The main crops include manioc, maize, the dry season is usually shorter than 3 months, al- groundnuts, bananas, and vegetables. The trees are though it is longer in Bas Zaire between Cabinda and varied, with some species occurring in the forest belts Angola. As a result, annual productivity is greater than to the north-Cdtis zenkefi, Clorophorm exceisa, Ter- forSeasonalMiombo Woodland, with mv values falling minaliasuperba, and Triplochitonscleroxylon, and some below 0.35 for only Zmonths (usually July and August). thathave been introduced, such as the oil palm (Elaeis InthewetterpartsofcentralZaire,NvivaluesreachO-58 guineensis). The presence of many light-demanding during the wet seasonL The phenology shows marked species is attributed to the open nature of the forest m seasonality, with a big reduction in productivity during this mosaic, which is probably a function of distur- the dry season. The values of wIw for a site in eastern bance and regrowth. Zaire show wet season values weU above 0.5 from Octo- Woody biomass productivity and sustainable yield ber to April, but a sharp reduction in momto 015 in are quite significant and fuelwood shortages are likely August (figure 11-3). to occur only m areas of concentrated cultivation. The The species occurringat thenorthem limitof this class regLonal growmg stock estimated for this class is 320 often include many from the humid tropical forest, but million tonnes, and the sustainable yield is 3.6 million Brartystia spp., kiobernia spp., Juibernardiaspp., and tonnes. Marquesia macroura are dominant Also cominmon,how- ever, are Aacia spp., Annona spp., Phitosfigma hnningii, Class 73-Cultivation and Forest Regrowth and Terminalia seicea. Quite dense thidcets exist in the Mosaic understory together with a mixed herbaceous layer. This class accounts for an estimated 3,191 million This land cover class occurs in two extensive areas and tonnes of growing stock in Zaire alone. The class is as a series of smaller patches. The area of greatest associated with quite high humana population densi- extentexistsinGabon,where itextendsfromRioMuni ties in some areas, especially near Kananga, Mbuji- (Equatorial Guinea) in the north, occupying a sector Mayi, and Kalemie. Maize, cassava, groundnuts, and from the coastnear Libreville and through much of the some cotton are the main agricultural crops. center of the country in the basin of the Ogooue River. In t-his area, commercial timber has been exploited Class 72-Cultivation and Forest/Woodland (Walker and Sillars 1967), and much of the area is now Mosaic cultivated. It is the second most important land cover class in Thisclass occurs south of the equator, generally at the Gabon, covering 21 percent of the land area (56,000 southerly edge of the Ombrophilous Humid Tropical square kilometers). In Cameroon, 47,000 square kilo- Forest (Class 87) and toward the northern limit of the 3meters are covered with this mosaic, some 9.4 percent 110 -EstimuiingWoody Biomnuss inSuibSahmarm: Africa of the land area. It occurs in the coastal lowlands to the Cultivation throughout this class includes large areas south of Douala and on the border with Nigeria to the of manioc. Other crops often .are grown in areas of north of Motnt Cameroon, where it attains altitudes secondary forest. to 1,500 meters. Elsewhere it exists in patches of vary- Fuelwood is relatively plentiful, as indicated by the ing size in eastem and southeastem Cameroon on the large growig stock of 285 million torrnes for the region. plateau at 500 to 700 meters and in patches throughout Sustainable yield is estimated at 3.1 million tonnes. the Guinean-Sudanian transition in CAR and northem- most Zaire. In cARit covers 34,000 square kilometers Class 74-Guinean Woodland and in Zaire 32,000 square kilometers. Within central Africa as a whole, it covers 4.percent This class occurs in a belt to the north of the Mesophi- of the land area and accounts for 2 percent of the lous Humid Tropical Forests (Class 85) where it shares growing stock. As a class, it does not correspond to a broad zone between 4e N and 8° N with Moist any of White's mapping units (White 1983). It occurs' Sudanian Woodland (Class 65). This zone runs from in conjunction with the forest classes and other high the west of Cameroon, where the Guinean Woodlands woody biomass mosaics (most notably Guinean are rather fragmented, through central cAR It contin- Woodland, Class 74, in cAR)and at the southern mar- ues to its southern extremity ini northern Zaire to the gin of tue Sudanian Woodland. The values of NDVI for south of the Oubangui River and in the vicinity of the this class in Gabon near the equator show a range of Parc National de la Garamba on the border with moderate values attaining 0.5.(figure 114). Sudan. The class constitutes 6 percent of the land area The key to understanding this extensive mosaic is of central Africa and is 1.6 percent of the growing that in most locations it has been greatly affected by stock. Thisincludes26.3 percent ofcAR (165,000 square human interference. In West Africa, this land cover kilometers) and 13 percent of Cameroon (60,000 class is sometimes known as "Farm Bush." Elsewhere square kilometers). it corresponds with the "secteur Preforestier" (see With the exception of occurrences in Cameroon. on Chapter 9, Classes 75 and 76). It is largely evergreen in Massif de l'Adoumaoua above 1,000meters, the Guin- the wetter, western parts of central Africa and semi- ean Woodlands generally exist at altitudes between deciduous at the drier end of the range in eastern CAR 400 and 800 meters. The rainfall of this area exceeds and northeastern Zaire. Extremely high rainfaLls of 2,000 millimeters a year in central Cameroon but is 2,000 to 4,000 millimeters a year are associated with typified by annual ranges of 1,300 to 1,600 nillimeters this class on the Cameroon-Nigeriaborder, whereas in in CAR.The wettest months are July to October and the the east, annual rainfall is only 1,300 millimeters. driest December to March. This is reflected in the In a class that covers many ecological zones, the tree vegetation productivity with rcvz values m central cAR species are of course quite vared. In Cameroon, spe- ranging from 0.16in February to 0.52 in August. des from the "Atlantic Evergreen Forest' dominate, Ecologically, this class occupies a transitional zone notablyCaesalpinaceae, whereas in Gabon andnorth- between the Guinean-Congolian floristic region to the em Zaire, species from the Mesophilous Humid Trp- south and the Sudanian floristic region to the north ical Forest (Class 85) occur. The remaining forest in (White 1983).As a result of the greater rainfall, woody this class is inevitably secondary, with light-demand- vegetation is quite dense in places, with trees and ing tree species such as Cfiorophoraexcelsa, Khaya an- shrubs separated by grasslands where buming for Eliotheca,Musanga cecropioides,and Terminaliasuperba. agriculture often has created local patches of herba- ceous wooded savanna (Laclavr&e1980). Gallery for- Figure 11-4. NDVI Profile, Cultivation and Forest ests often exist along water courses, being more fre- Regrowth Mosaic (Class 73) quent at the southern edge of the zone. The main tree and shrub species include Burkea africana, Daniellia :0.6 oliveri, Hymenocardia acida, Lophira lanceolata, and -05 -73 Gabon Uapacaheudelotii Many of these species have high calorificvalues and are importantsources of fuelwood OA/\ and high-qualitycharcoaL (2 / \Growing C stock for this class is estimated at 440 In 0.3- /million tonnes and sustainable yield at 4.8 million zonnes. The combination of closed canopy woodland 0.2- os :and high sustainable yieldwith low to moderate pop- 0.1 - ulation density indicates few woody biomass supply problems. Only when supplies from the neighboring o , , , , , , , , -, , ,* , SudanianWoodlandsbecomescarceisthisclasslikely -Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec to come under pressure. CentralAfricm111

Class 82-Evergreen Forest occur. On thehigherslopes, the forest often exists only on the steepest rocky slopes wlere It has escaped This class occupies less than 2 percent of central AfriCd clearance. and represents an estimated 1.9 percent of the growing In eastern Zaire, this zone Is moderately well popu- stock. It occurs almost exclusively in eastern Zaire, lated and much of the forest has been cleared. Grow- where it represents a transition between the lowland ing stock is estimated for Zaire at 434 million tonnes, humid tropical forests of the Zaire Basin and the mon- with a sustainable yield of 36 million tonnes. tane classes with less woody biomass on the westem Most of the areas occupied by this land cover class wall of the Rift Valley. Leonard (1965) identifies this are rural, with few large urban ce .ters. Wood is not as area as representing the eastern extremity of the a rule exported from here and the only threat Is further Guineo-Congolian phytogeographic zone. cleara ;ce for agriculture. The class is represented by a scattering of small areas among woodlands and areas of secondary forest Class b6-Mesophilous Humid Tropical Forest and cultivation; no one area is particularly extensive. This pattem probably results from the widespread Mesophilous Humid Tropical Forest is marginal to the clearance this class has undergone because it occurs narrow belt of the Ombrophilous Humid Tropical on accessible terrain between 1,100 and 1,800 meters Forest (Class 87). It occupies 10 percent of the land above sea level. The greatest concentrations exist on cover of central Africa and is an estimated 18 percent the Dorsale du Kivu and have been described in some of the growing stock. Its distribution in central Africa detail by Pecrot and Leonard (1960) and mapped by is best described with reference to those areas north Devred (1960). and south of the equator. The climate of this area is moist with the high hu- To the south of the equator, a coastal belt stretches midities typical of cloudy montane regions. Rainfall is from Cabinda in an unbroken swathe across Congo greatest on the upper slopes and temperatures highest and reaches its broadest development in southem toward the lowland margin, so a complex mix offorest Gabon, where it stretches from the coast for 200 kilo- types that changes rapidly with altitude is encoun- meters inland. A few other small patches exist in Zaire tered; this pattern is largely controlled by climate and to the south of the main area of Ombrophilous Humid altitude. The phenology shows a wet season of 6 Tropical Forest (Class 87). months from November to April, with mmVvalues To the north of the equator, this class is much more readcing 0.58 and a drier period from June to October extensive. Here it is an eastward continuation of the with vNvalues below 0.3 (figure 11-5). West African peripheral domain of the Guineo- The canopies of these forests are rarely as high as Congolian phytogeographic region (Leonard 1965).It thoseintheZaireBasin,withtheupperstratumattain- extends from the Nigerian border, where the pattern ing20 to25 meters orlessathigheraltitudes. The lower is broken by the uplands of the Bamileke Plateau, slopes are characterized by contact with the lowland throughout central Cameroon into the north of Rio rain forest and species such as Cynometra alexandr, Muni, Gabon, and Congo. It continues via the south- Julbernardia seretii, Lebrunia bushaie, Pentadesma em tip of cARto northemZaire, where it occurs as a large lebrwuii,and Symphonia globuliferaare commonly en- area in Haut Zaire along the tributaries of the OubanguiL countered. Higher up,Aningeria adoli-friedericii,Fical- Zaire has by far the, largest area within this land hoa laurifolia,Ocotea usambarensis, and Podocarpusspp. cover class of any country in Africa-more than 200,000square kilometers (8.9 percent), whereas Cam- Figure 11-5. NDVI Profries, Forests (Classes 82, 85, eroon has 19.6 percent of its area within t class, and 87) about 88,000 square kilometers. Gabon has 36,000 square kilometers; Congo 26,000 square kilometers; 0.6- cAR 40,000 square kilometers, and Rio Muni Z,500 square kdlometers. Phenologically, thits class demonstrates greater sea- 04- V \&t . /,,t' / : sonality than Ombrophilous Humid Tropical Forest (Class 87). Because some of the area of this class corre- n 0.3- \ sponds to White's "Drier Guineo-Congolian Rain Forest," it is not surprsing that NDV values are lower. 0.2-Easem zaim 82 For a Southern Henmisphere site in southern Gabon, 0.1- I 8s aircBsi, NDVI values increase from 0.32 in January to 0.46 in 87Cetr air June, reducing dramatically in the dry season to about a- , 0.12 between July and Septeniber, and increasing to Jan Feb Mar Apr May Jun J'l Aug Sep Oct Nov 0.35 again by November. 112 EstimatingWoody Biomnss in Sub-SaharanAfican

In Haut Zaire, along the border with CAR in the It is principally surrounded by Ornbrophilous Oubangui Basin, these forests occupy land above 500 Humid Tropical Forest (Class 87) and includes much meters altitude. Here the NDVI values increase to of the area mapped by White as "Swamp Forest." greater than 0.48from September through to May, and Many authors (for example, Lcbrnm and Gilbert 1954) reduce to 0.36 in July and August (figure 11-5). In havesubdividedswampforesttodistinguishbetween central Cameroon, to the east of Yaounde, on the south riparian or floodplain forest and forest that occupies Cameroon plateau above 500 meters, a similar NovI drained sites (often with waterlogged, clay soils). pattern exists to that in Haut Zaire, but with slightly Many swamp forests are periodically inundated with increased seasonality, indicating 2 months with low water, especially during the wet season. productivity-June (0.35)and December (0.27). Climatically, this class occurs in conditions very These Mesophilous Humid Tropical Forests, being similar to those of Ombrophilous Humid Tropical farther from the equator than either the Humid Trop- Forest (Class 87), with annual rainfall exceeding 1,500 ical Swamp Forests (Class 86) or the Ombrophilous millimeters.The NDvivalues show little seasonality, as Hurnid Tropical Forests (Class 87), are generally char- would be expected of a class occupying an area so acterized by a more definite dry season, often with a dose to the equator. distinct period of 2 dry months. Rainfall for this land Phenologically,these forests are separated from the cover class ranges from 1,200 to 1,60 millimeters a Ombrophilous Humid Tropical Forests (Class87) of the year, although some parts of westem Cameroon are drier soilsby owlevels that are slightly smaller overalL wetter. Most tree species are briefly deciduous, al- The depression of No values may be attnbuted in part though few trees are leafless at the same time; hence to the presence of standing surface water, which may the widely applied term "semideciduous. - appear through gaps in the even tree canopy. Its The broad extent of this forest type demonstrates a low reflection coefficient will depress NDcvvalues in wide range of species. Some areas have dominant .mixed pixls of standing water and tree canopy. species, whereas others are dharacterized by a consid- Wetter sites are host to species such as Guibourtia erable mixture In the Mayumba Forest of westem devneusetMitragynaspp.,Raphiaspp.,Symphoniagtobu- Congo and southern Gabon, the most important trees lijfera,and Ulapacaguineensis. Badly drained sites sup- are Chlorophoraexcelsa, Klainedoxagabonenszs, Peter- port similar species, as well as Phoenix recdinataand sianthus macrocarpus,Sarcocephalus diderrihi, and Ter- Xylopiarubescens. minatliasuperba To the north of. the equator, these Accessibilityisverylimited and population density forests often are floristically better characterized than is generally very low in this class. Growing stock is in Gabon-Congo, with the occurnce of species such estimated at 2,830 milion tornnesfor the region, with as Celtis zenUeri,Chlorophora excelsa, Musanga cecro- a sustainable yield of 327million tonnes. pioides,and Piptadeniastrumafrcanum. Most of these more common species are widely distributed, from Class 87-Ombrophilous Humid Tropical Cameroon irough southernmost CARtin northern Forest Congo, and in the north of the Zaire Basin toward the border with Sudan. This class represents areas with consistently greater These forests often are inaccessible and dearly rep- wNo values and corresponds to White's "Wetter resent a significant woody biomass resource. Agicul- Guineo-Congolian Rain Forest" and "Les Forets Om- ture is practiced in many areas of this land cover class, bropbilesSempervirentesEquitoriales" of Lebrun and but forest clearance has been local rather than exten- Gilbert (1954).It occupies a belt centered on the equa- sive.Growingstockfortheregionisanestimated5,033 tor and largely within 30 or 40 of it, although a large milion tonnes, with a sustainable yield of 583 million outlier exists in central CuR at 8" N. Its broadest extent tonnes. is in the center of the Zaire Basin on terrain between 300 and 500 meters above sea level. It is a particularly Class 86-Humit Tropical Swamp Forest important class for woody biomass, covering 20 per- cent of central Africa and providing an estimated 30.9 This class is restricted to a narrow belt near the equa- percent of the growing stock tor, running eastward from the coast of Rio Muni It formsasignificantelement in thevegetationof all through northern Gabon, southernmost Cameroon, central African countries, with more than half a mil- Congo, and into Zaire in the province of Equateur. lion square kilometers in Zaire (24percent of the area); Here it extends to the north of Mbandaka between the 95,000square kilometers in Congo (28 percent); 55,000 Oubangui and Zaire rivers. Other isolated areas exist square kilometers in Gabon (21percent); 63,000square within the Zaire Basin- It is an important class, repre- kilometers in Cameroon (14 percent); 52,000 square senting 6 percent of the area of central Africa and 10.1 kilometers in Ct (8 percent) and 5,000 square kilome- percent of the growing stockL ters in Rio Muni (22 percent). CentralAfica 113

To the east, this class merges with Evergreen Forest Land Cover Class Tables (Class 82), to the north and west with the Mesophilous Humid Tropical Forest (Class 85), ae:d to the south Tables 11-1through 11-6,beginning on page 115,pres- with the two minombowoodlands (Classes 66 and 67). ent summaries for each land cover class of the area, Ombrophilous Humid Tropical Forest often occurs on showing growing stock and sustainable yield for the better-drained soils of the Zaire Basin. Within it, on central African nations of Cameroon, Central African riverine sites, patches of Humid Tropical Swamp For- Republic, Congo,. mainland Equatorial Guinea, est (Class 86) exist Gabon, and Zaire. The phenology of Ombrophilous Humid Tropical Forest reflects the generally even distribution-of rain- References fallof the equatorialbeltand thelackofenvironmental stress on plant growth. The values of NDVI are consis- Every effort has been made to facilitate access to the tently above 0.35 and usually are about 0.5 in the documents listed here. Some documents, however, wettest months. The least variation is displayed by lack full bibliographic information because it was sites in the vicinity of Kisangani (Zaire), whereas with unavailable; also, some documents are of limited increasing distance from the equator, a measure of circulation. seasonality occurs, with smaller values notable inJuly and January. This class as a whole, however, is differ- Barber, K. B,S.A. Buchanan, and P. F. Galbreath. i980. entiated from surrounding land cover classes on two An EcologicalSurvey of the SL FlonisNational Park, criteria,namelythelackofappreciableseasonalityand CentralAfrican Republic. Washington, D.C.: Interna- consistently large NDvi values (figure 11-5). Rainfar tional Park Affairs Division, National Park Service, within the region covered by Ombrophilous Humid US. Department of the Interior. Tropical Forest is evenly distributed throughout the Chidumayo,E.N.1987."SpeciesStructureinZambian year, with a mean annual total in the range 1,500 to MiomboWoodland." Journalof TropicalEcology 3(2): 1,900 millimeters, although it may be locally greater. 109-18. The ecology of this type of rain forest is dominated Devred,R. 1958. "Lav6g6tation forestiAredu Congo et by tall, closed-canopy tree species which typically du Ruanda-Urundi." Bulletin ie la Soci&6Forestibre attain. 35 to 45 meters in height The fairly evenly Belge65(6):409-68. distributed rainfall with only a short dry season cre- Devired,R. 1960."La cartographie de la veg6tation au ates a semi-evergreen forest with a mixture of ever- Congo Belge." BulletinAgicolede CongoBeige 51(3): greens and some species thatbriefly shed their leaves. -529-41. Few detailed descriptions of this forest have been Fahem, A. K 1978."Vegetation." In G. Laclav&e,Atlas published from the area of its largest extent in central de la Republiquedu Zaire.Paris: Les Editions Jeune Zaire. Here, as in much of the Zaire Basin, Brachystegia Afrique. laurentiiand Gilbertiodendrondewevrei often are domi- Jongen, P., M. Van Oosten, C. Evrard, and J.-M.Berce. nant in the upper stratum of the forest. 1960. Notice explicativede Ia carte des sols et de la Fahem (1978) reports that Gilbertiodendronspp. in vdtatidom No. 11, Ubangi [regioni. Brussels: iNEAc northeastern Zaire (Ituri) sometimes represent 80 per- (L'InstitutNational pour ['Etude Agronomique du cent of the canopy species. Cynometra alexandri, Congo Belge). Julbernardiaseretii, Oxystigmaozyphyllurn, and Scoro- Laclavxe, G.1978. Atlasdela RipubliqueduZaire.Paris: *dophloeuszenkeri also are important, but gradual. Les Editions Jeune Afrique. changes occur in composition throughout the large Laclavere, C. 1980.Atlas of the UnitedRepublic of Cam- area covered by this class. For instance, in the area of eroon.Paris: Les Editions Jeune Afrique. this land cover class occurning in southwestern Cam- Lebrun, J., and G. GilberL 1954L"Une classification eroon, Cesalpinaceae are dominant. A detailed study ecologique des forets du Congo." Sei Scientifique of species in southern Cameroon is orovided by No. 63. Brussels. WEmAc(Llnstitut National pour Vivien and Faure (1985).The pror-lent northerly l'Etude Agronomique du Congo Belge). outlier of this class in centralcARis less dense than that Leonard,J. 1965."Contribution a la subdivision phyto- of the Zaire Basin and includes species such as geographique de la r6gion Guineo-Congolaise Enythrinatomentosa and Ochthocosmusafricanus. d'apres la repartition g6ographiqued'euphorbiacees Clearly, this belt of Ombrophilous Humid Tropical d'Afrique tropicale." Webbia19(2): 627-49. Forest currently is one of the world's greatest re- Malaisse, F. 1978.'"he MtiomboEcosystem. In uNESoO sourcesof woodybiomass.Growingstockisestimated (lJnited Nations Educational,Scientific and Culhural to be 8,644 million tonnes, with sustainable yields of. Organization),Troicl ForestE&systems. Paris UN!o. 1,218 million tomnas. Much of this forest remains gen- Malaisse, F. 1984. "Structure d'une foret dense seche erally intact with very low population densities. Zambezienne des environs de Lubumbassi" Bullt- 114 EstimatingWoody Bimass in Sub-SaharanAfrica

tin de la Soci6tARoyale de Botaniquede Belgique117(2): -Kivu [region]. Brussels: INEAc(L'Institut National 42&-58. pour L'Etude Agronomique du Congo Belge). Malaisse, F. 1985. "Comparson of the woody struc- Vennetier, P., and G. LaclavLre.1977. Atlasde la Rpub- ture in a regressive Zambezian succession." Bulletin lique Populairedu Congo.Paris: Les Editions Jeune de la Soci*teRoyale de Botaniquede Belgique118(2): Afnique. 244-65. Vivien, J., and J. J. Faure. 1985.Arbres desforhts denses Malaisse, F., and K Binzangi. 1985."Wood as a Source dAfrique Centrale.Paris: Agence de Cooperation of Fuel in Upper Shaba.' Commonweath Forestry Culturelle et Technique. Review64(3):227-39. Walker, A., and R. Sillars. 1967. Les plantes utiles du Millington,Andrew, and J. Townshend. 1989.Biomass Gabon.Paris: Editions-Paul Lechevalier. Assessment.London: Earthscan. White, F. 1983. "The Vegetation of Africa." Natural Mullenders,W. 1954. "a vegftafion deXaniama" Sbie ResourcesResearch Seres 20. Pars: UNESCO/AErFT/ Scintiuque No. 61.Bmrussels: w (LInslt National uNso (United Nations Educational, Scientific and pour irEtudeAgronornique du CongoBelge). CulturlCrganizatin/Associationpourl¶EtudeTaxo- Pecrot, A., and A. Leonard. 1960.Notice explicative de la nomique de la Flore de l'Afrique Tropicale/United carte des sols et de la V$gitation.No. 16, Dorsale du Nations Sudano-SahelianOffice). CentralAfrica 115

Table 11-1. Land Cover Clasines-Cameroon (Central Africa Region) Arem Grouingstock Sustainableyield Thousand Thousandtonnes Landcover class km2 Pernt tonnes Percent peryear Percent 0 105 0.02 0.00 0.00 0.00 0.00 12 2,687 059 609.95 0.02 26.87 0.01 1 2,687 059 609.95 0.02 26.87 0.01 21 105 0.02 34.65 0.00 1.05 0.00 22 -2,65 a.5 869.55 0.03 26.35 0.01 23 790 0.17 260.70 0.01 7.90 0.00 2 3,530 0.77 1,164.90 0.04 3530 0.01 41 158 0.03 219.62 0.01 3.32 0.00 43 632 0.14 1,0i6934 0.03 13.27 0.00- 44 10,961 2.43 1,545.50 0.05 383.64 0.12 4 11,751 2.60 2,834.46 0.09 400.23 0.12 52 685 0.15 1,472.75 0.05 43.16 0.01 5 685 0.15 1,472.75 0.05 43.16 0.01 62 34,779 7.70 92,859.93 3.00 2,677.98 0.82 63 685 0.15 1,82.95 0.06 30.14 0.01 64 21,974 4.86 58,670.58 1.89 1,010.80 0.31 65 65,289 A1445 174,321.63 5.62 3,133.87 0.96 6 122,727 27.16 327,681.09 10.57 6,852.89 2.10- 73 42,5 9.41 71,612.10 2.31 807.98 0.25 74 59,915 13.26 100,896.86 3.26 1,138.38 0.35 7 102,440 22.67 172,508.96 5.57 1,946.36 0.60 81 8,906 1.97 219,800.08 7.09 26,263.79 8.03 84 53 0.01 524.70 0.02 21.04 0.01 85 88,370 1955 1,129,191.86 36.44 130,7B7.60 39.99 86 45,792 10.13 585,130.18 18.88 67772.16 20.72 87 62,750 13.88 658,18475 21.24 92,870.00 28.40 8 205,871 45.54 2,592,831.57 83.66 317,14.59 97.15 Lakes 2,161 0.48 0.00 0.00 0.00 0.00 Total 451,957 100.00 3,099,103.68 100.00 327,019.30 100.00 (Perenlge of region) (11.42) -(11.07) (13.75) Note:In the followingtables, details may not add to totalsbecause of roundin&g Sw= Authors'cakulatons fromdata basesderived frm landcover dassification and table4-1. 116 EslimnatingWoody Biomnass in Sub-Salwnzn Africa

Table 11-2. Land Cover Classes-Central African Republic (Central Africa Region) Area Growingstock Suslfiizableyield Thousand Tlhotsaid tonnes Landcover cdass b,,?2 Percent Ioniztes Percenzt per wear Percent 12 lOS 0.02 23.84 0.00 1.0S 0.00 1 105 0.02 23.84 0.00 1.05 0.00 23 105 0.02 34.65 0.00 1.05 0.00 2 105 0.02 34.65 0.00 1.05 0.00 44 105 0.02 14.80 0.00 3.68 0.00 45 685 0.11 1,267.93 0.05 14.39 0£' 4 790 0.13 1,282.74 0.05 18.06 - ioj 52 1,212 019 2,605.80 0.11 76.36 0.04 5 1,212 0.19 2,605.80 0.11 76.36 0.04 62 28,297 4.53 75,552.99 3.17 2,178.87 1.27 63 2,108 034 5,62836 0.24 92.75 0.0f- 64 27,928 4.47 74,567.76 3.13 1,284.69 0 - 65 263,107 42.15 702,495.69 29.51 12,629.14 A 6 321,440 51.49 858,244.80 36.05 16,185.45 .9.46 73 33,936 5.44 57,148.22 2.40 644.78 0.38 74 164,673 2638 277,309.33 11.65 3,128.79 1.83 7 198,609 31.81 334,457.55 14.05 3,773.57 2.21 85 40,048 6.42 511,733.34 2150 59,271.04 34.5 86 9,591 1.54 122,553.80 5.15 14,194.68 8.30 87 52,379 8.39 549,403.33 23.08 77,520.92 45.32 8 - 102,018 16.34 1,183,690.47 49.73 150,986f64 88.27 Total 624,279 100.00 2,380,339.85 100.00 171,042.17 100.00 (Percentage of region) (15.77) (8.50) (7.19) SourocAutiois' calculationsfrom data bases derivedfrom land cover lassificationand table4-L

Table 11-3. Land Cover Classes-Congo (Central Africa Region) Area Grouwingstock Sustainableyield Th-ousand 7housandtonnes Landcover class kn? Percent tonizes Percent per year Percent 24 474 0.14 29.39 0.00 4.74 0.00 25 22,922 6.76 7,564.26 029 229.22 0.08 2 23,396 6.90 7,593.65 0.29 233.96 0.09 33 1,423 0.42 1,423.00 0.05 71.15 0.03 3 1,423 0.42 1,423.00 0.05 71.15 0.03 42 3,952 1.17 7,315.15 028 82.99 0.03 43 2,529 0.75 4,279.07 0.16 53.11 0.02 4 6,481 1.91 11,594.22 0.45 136.10 0.05 61 - 1,107 0.33 3,254.58 0.13 48.71 0.02 65 2,002 0.59 5,34534 0.21 96-10 0.04 66 62,180 18.35 345,907.34 13.30 5,534.02 2.03 67 4,005 1.18 47,659.50 1.83 532.67 0.20 6 69,294 20.44 402,166.76 15.47 6,211.50 2.28 71 1,423 0.42- 730.00 0.03 27.04 0.m1 72 51,589 15.22 86,875188 3.34 980.19 0.36 73 2,846 0.84 4,792.66 0.18 54.07 0-0 74 685 0.20 1,153.54 0.04 13.01 0.00 7 56-543 16.6i 93,552.08 3.59 1,07431 0.39 81 632 019 15,597.76 0.60 1,863.77 0.69 82 2,687 0.79 16,122.00 0.62 1,338.13 0.49 83 3,109 0.92 27,601.70 1.06 1,548.28 0.57 85 26,348 7.77 336,674.74 12!95 38,995.76 14.34 86 54,487 16.08 696,234.89 26.78 80,640.76 29.64 87 94,535 27.89 991,577.62 38.14 139,911.80 51.43 8 181,798 53.64 2,083,808.71 80.15 264,297.78 97.16 Total 338,935 100.0 2,600,138.41 100.00 272024.79 100.00 (Percentage of regon) (85) (9-29) (11.44) SOUrc:AuthOrS' calculatins fromdata baseSderived from land cover classifiton and table4-1. CentralAfiica 117

Table 114. Land Cover Classes-Equatorial Guinea (Mainland; Central Africa Region) Area Groudngstock Sustainableyield Thousand Thtouswndtonnes Landover class km2 Percent tonnes Percent perwar Percent 22 211 0.94 69.63 0.03 2-11 0.01 2 211 0.94 69.63 0.03 2.11 0.01 41 105 0.47 145.95 0.05 2.21 0.01 4 105 0.47 145.95 0.05 2.21 0.01 52 738 3.27 1,586.70 0.59 46.49 0.15 5 738 3.27 1,586.70 0.59 46.49 0.15 64 211 0.94 563.37 0.21 9.71 0.03 65 422 1.87 1,12674 0.42 20.26 0.06 6 633 2.81 1,69011 0.63 29.96 0.09 73 1,528 6.77 2,573.15 0.96 29.03. .O9 74 53 0.23 89.25 0.03 1.01 0.00 7 1,581 7.m 2,662.40 0.99 30.04 0.09 81 2,424 10.75 59,82432 22.23 7,148.38 22.47 84 369 1.64 3,653.10 -1.36 146.49 046 85 2,529 11.21 32,315.56 1201 3,742.92 11.76 86 9,064 40.19 115,819.79 43.03 13,414.72 42.16 87 4,901 21.73 51,406.59 19.10 7,253.48 22.80 8 19,287 85.51 263,01936 97.73 31,705.99 99.65 Total 22,555 100.00 269,174.16 100.00 31,816.80 100.00 (Percntageof region) (0.57) (0.96) (1.34) Saw=ctAuthor' calclibtionsfrom databases derved from landcover dasification and table4-L:

Table 11-5. Land Cover Classes-Gabon (Central Africa Region). Area Growingstock Sustainble yield Thousand Th1ousandtonnes Land cover cdss kM2 Percent tonnes Percent per Vear Percent 11 422 . 0.16 95.79 0.00 4.22 O.DO 1 422 0.16 95.79 0.00 4.22 0.00 24 -1,054 0.40 65.35 0400 10.54 0.00 25 6,323 2.42 Z,08659 0.10 63.23 0.03 2 7,377 2.82 Z151.94 0.11 73.77 0.03 33 4,005 1.53 4,005.W0 0.20 200.25 0.09 3 4,005 1.53 4,005.)0 0.20 200.25 0.09 42 738 0.28 1,366.04 0.07 15.50 0.01 43 3,689 1.41 -6,241.79 0.31 77.47 0.04 4 4,427 1.69 7,607.83 0.38 92.97 0.04 51 263 0.10 -586.49 0.03 16.57 0.01 52 1,212 0.46 2,605.80 013 76.36 0.04 5 --1,475 0.56 3,192.29 0.16 92.92 0.04 61 474 0.18 1,393.56 0.07 20.86 0.01 65 422 0.16 1,126.74 0.06 20.26 0.01 66 19,339 7.40 107,582.86 5.40 1,721.17 0.80 67 1,528 0.58 18,183.20 0.91 203.22 0.09 6 21,763 8.32 128,26.36 6.44 1,965.51 0.91 71 1,423 0.54 730.00 0.04 27.04 0.01 72 18,812 7.19 31,679.41 1.59 357.43 0.17 73- 56,2 21.52 94,773.84 4.75 1,069.30 0.50 74 580 0.22 976.72 0.05 11.02 0.01 7 77,094 29.47 128,159.97 6.43 1,464.79 0.68 81 4,743 1.81 117,05724 5.87 13,987.11 650 82 8273 3.16 49,638.00 2.49 4,119.95 1.92 83 1,107 0.42 9,827.95 0.49 551.29 0.26 84 949 036 9,395.10 0.47 376.75 0.18 85- 36,307 13.89 463,930.85 23.27 53,734.36 24.98 86 36,836 14.85 496,246.41 24.90 57,477.28 26.72 87 54,693 20.92 573,674.88 28.78 80,945.64 37.63 8 144,908 55.41 1,719,770.42 86.28 211,192.38 98.19 Total 261,471 100.00 1,993,26958 100.00 215,086.80 100.00 (Percentage of region) (6.61) (7.12) (9.04)

Source: Aufhorst calcalaions fm databases derived fromnland cover dassificationand table4-1. 118 EstimatingWoody Biomass in Sub-SaharanAfrica

Table 11-6. Land Cover Classes-Zaire (Central Africa Region) Anra Growingslock Sustainableyield Thiousand P- Tiousand lonnes Landcoverctass km' Pcrce7at tonnes Prcent peryear Percent

1- 14,017 - 0.62 3,181.86 0.02 140.17 0.01 14 105 0.00 23.84 0.00 1.05 0.00 1 14,122 0.63 3,205.69 O.02 14122 0.01

-23 580 0.03 191AO 0.00 5.80 0.00 24 4,690 021 290.78 0.00 46.90 0.00 25 1,686 0.07 55638 0.00 16.86 0.00 2 6,956 0.31 1,038.56 0.01 69.56 0.01 33 2,002 0.09 2,W2.00 0.01 100.10 0.01 3 2,002 0.09 2,002.00 0.01 100.10 0.01

42 18,233 0.81 33,749.28 0.19 382.89 0.03 43 -6.060 0.27 10,253.52 0.06 127.26 0.01 45 1,950 0.09 33,609.45 0.02 40.95 0.00 .4 26,243 1.17 47,612.25 0.27 551.10 0.04

- 51 211 0.01 -47053 0.00 13.29 0.00 52 790 0.03 1,69850 0.01 49.77 0.00 5l - 1.001 - 0.04 2,169.03 0.01 63.06 0.00

61 5,322 0.24 15,646.68 0.09 234.17 0.02 65 -943,157 1. 115,229.19 0.65 2,071.54 0.15 66 767,717 33.98 4,270,809.67 24.18 68,326.81 5.02 67 268,219 11.87 3,191,806.10 18.07 35,673.13 2.62 6 1,084,15 48.00 7,593,491.64 43.00 106,305.64- 7.81

71 21,025 - 0.93 10,785.83 0.06 399A7 0.03 72 119,934 5.31 201,968.86 1.14 2,278.75 0.17 73 32,250 1.43 54,309.00 0.31 612.75 0.05 74 35,622 1.58 59,987.45 0.34 676.82 0.05 -7 -- -- - 208,831 9.25 327,051.14 1.85 3,967.79 0.29

82 72,403 3.20 434,418.00 2.46 36,056.69 2.65 83 1,950 0.09 17,312.10 0.10 971.10 0.07 84 3,794 0.17 37,560.60 0.21 1,506.22 0.11 85 200,295 8.87 2,559,36951 14.49 296,436.60 21.77 86 63,709 2.82 814,073.60 4.61 94,28932 6.92 87 554,851 24.56 5,819,832.14 32.96 821,179.48 60.31 8 897,002 39.71 9,682,565.95 54.83 1,250,439.41 91.83

Lakes 18,707 0.83 0.00 0.00 0.00 0.00

Total 2,259,279 100.o00 17,659,136.26 100.00 1,361,637.89 100.00

(Percentage of region) (57.07) (63.07) (57.24)

Sourc Authors'calculations from data basesderived fron landcover dassification and table4-1. ff2 East Africa Phil O'-Keefe,Ian Ryle, and John Kiarkby

Thiis chapter presents, a detailed description of the year but is unreliable. A slight tendency exists for motmortantIlandcover classes inthis region. Help- rainfall maxima in April and November. ful figures in other chapters include figur 3-1 (cloud Much of the area. classified.as Desert in thiis study cover); figures 3-2, 3-3, and 3-4 (NDvisummary land has a surface largely of bare rock. Other areas in this cover profiles); figure 3-5 (regional summary map of land coverdclssprobably represent White's-"semides- land cover classes); figures 7-1 and 7-2 (continental. ert Annual Gralssland" (1983)which, along with true maps of growing stock and sustainiableyield); and the desert, occupies the driest areas of Kenya, nearly al- "RegionalLand Cover ClssMap of East Africa"atthe ways below 1,000 meters. These areas are domidnated enid of this volune. b ythe grdssesArisda adscensionisand A. mntabilis, but Helpful tables in other chapters incude tbe32 these may disappear completely during drou ghtperi- (lad cover classes); table 4-1 (data and sources for ads lasting several years- growing stock and sustahinableyield); and table 6-5 Even here, however, woody plants are rarely ab- (East Africa estimated woodY biomass by summary sent, and theyprovide 2 to 20lpercentof the vegetatio class). cover. Domninantsmay be either shrubs, such as Duo- spermneremphilum or bushes and small trees, notably Class 0-Desert AcaciaJwomda, A. reficens,A seyal,A. fortilis,A senegal, and Comzmiphoraspp. It is worth remembering that the The only significant areaLsof this land cover clas in the ftrnsitionfrombusbland.todesertthrough semidesert East African region occur in northern and eastern is very gradual, and many so-called desert areas may Kenya, especiallyinMarsabitDistrct andon the west- differ only in vegetation densty from the land cover em side of Lake Turkana, with smaller areas running clas that surrounids;them.L Thims maybe a result oflocal parallel to the KCenyancoast Desert covers 2.4 percent and climatic faLctorsat thtetime. of Kenya, an area of 14,439square kidlometers. Some vegetation is present in most areas classed as Accordingto Morgan (1973),only the ChalbiDesert -desert, and this presents opportunities for mnigrant ofMarsabitDistrictisdlassed as true desert Itisa rock pastoralists,who use grasses and leaves as fodder. The desert of a type unique in East Africa and forms part vegetation is resident, adapted to survive irregular Of a closed drainage basin. The edge of the desert is periods of severe drought and to respond quickly to marked by n-umeroussprings, suppliedby subsurface any water that bec-omes available. Locally, overuse water from the sLurroundingmountains. The desert is may lead to at least the early stage of desertification. liable to occasional flooding, and subsequent evapo- ration of the floodwater results in an accumulation of Class 21-Semidesert Wooded Grassland salt, which inhibits plant growfth Locally, however, outlets of significant tributary streams formed by sea- Semidesert Wooded Grassland is restricted to the arid sonal floods may support a variety of ainnual herbs areas of north Kenya, where the annual -rainfall is and grasses, such as the halophytic grass Dnzkebrock- less than 250 millimeters, with maxima in April and maniasomalensis. Rainfall is less than 100 milimeters a November. The greatest area is around Lake Turkana

119 120 EstimnalingWoody Biomass in Sub-Sahamn Africa in Kenya, extending southward and eastward toward country. The largest blocks of this vegetation are in the the border with Somalia. This class accounts for 17.7 northern provinces of Arusha and Tanga, but signifi- percent of Kenya, an area of 104,600square kilometers. cant outliers are scattered throughout the country, Growing stock for the region is 34 million tonnes and notably in Dodoma, Morogoro, and Tabora districts. sustainable yield is 1 million tonnes a year. The dry season here lasts about 6 months. The transition is gradual from Dry Acadca-Commi- Transitional Wooded Grassland also occurs in phoraBushland and Thicket (Class 41) to Semidesert Burundi, especially in the northwest, and covers 2.6 Wooded Grassland (Class 21). The latter consists percent (658square kilometers) of the country. Grow- mainly of widely spaced dwarf shrubs and bushes ing stock for the region is about 2 million tonnes and with a grass cover that is barely discemible except in sustainable yield is 300,000tonnes a year. the wetseason.The importantwoody species areAca- In Tanzania, this class is probably similar to the cia mellifera,A. reficiens,A. senegal,and A. tortilis ss. "Acacia-CommiphornDeciduous Wooded Grassland" spirocarpa,along with Commiphoraspp. Other genera described by White (1983).Canopy cover is less than indude Balanites,Boscia, Euplorbia, Jatropha, and San- 40 percent, with the woody vegetation dominated by sevieria.Various succulents also grow in these areas, Acaciaspp. or Commiphoraspp. thorn trees that form a and the grasses include Aristidaspp. and Chrysopogon single, open stratum. Trees are usually between 4 and aucheri var. quinqueplmris(Trapnell and Langdale- 7 meters in height, although they may attain between Brown 1972). 9 and 20 meters in a few species. Very few bushes and Crown cover is usually less than 10 percent (White shrubs exist, although scattered bushes or small 1983) and continuous areas of taller trees are almost groups of Grewiafallaxand Cordiaovalis occasionally entirely restricted to rocky outcrops and sites where form a very open understory. water is available, for example near streams. In drier The grass cover is fairly well developed and ranges areas, with about 100 millimeters of rainfall, woody from 0.5 to 1.5 meters in heighL Principal species plantcoverislessthan3percent, andindividualplants include Digitariamacroblephara, Eustachys paspaloides, usually are less than 3 metershigh(White 1983).Grasses and Themedatriandra on well-drained soils and Pen- such as Cendirusbiflorus and Panicumturgidum domi- nisetum mezianumon poorly drained soils. The small nate the drier areas. amount of Transitional Wooded Grassland in north- Much of the area of Class 21 has long been used for western Burundi lies in an area of 'Wooded Savanna" grazing and browsing. This has strongly influenced dominated by Acaciaspp. (MHirit 1986) and will be the grasses, herbs, and trees, because the more palat- described more fully under Open Woodland (Class able species such as Acacia sencgal are suppressed. 61) in this chapter. Fluctuations in rainfall and occasional droughts can The other areas probably correspond to the most be tolerated by the resistant vegetation, but overuse important East African savanna type, the "small Tree of. the biomass by pastoralists has caused general Savanna." This is dominated by various broad-leaved degradation of the environment, with severe social Combretumspecies, most commonly C. binderanum,C consequences. ghasalense,C molle,and C zeyheri.In wetter areas, the "small Tree Savanna" also includes large-leaved Ter- Class 24-Transitional Wooded Grassland minalia spp., especially T. glaucescensand T. mollis. These are replaced in drier areas by smaller-leaved Transitional Wooded Grassland occurs at heights of species-T.browniiin Kenya and T.sericeainTanzania. approximately 1,000meters, mainly in north Tanzania The ground cover between the trees is mainly tall and south Kenya, but occurs also in scattered areas of grassland, dominated by Hyparrheniaspp. It is possi- central and southern Tanzania. ln Kenya, it grows ble that the savanna flanking the Kenya Highlands extensively on the southern and eastern flanks of the includes certain other Acaciaspp. observed in south- highlands in the south, and forms a distinct band em Kenya (Trapnell and Langdale-Brown 1972);spe- along the coastal hinterland separating the MoistAca- cies involved include Acaciagerrardii, A. nilotica, A. cia-CommiphomaBushland and Thicket (Class 43) to- senegal,and A. seyalss. subalata,in a grass layer domi- ward the coast from the Dry Acacia-CommiphormBush- nated by Themedaspp. land and Thicket (Class 41) of the interior. Land use in Transitional Wooded Grassland is Rainfall in this area is about 250 millimeters, with a more variable than in the groups previously de- November-December mnaximurn'This class accounts scribed. Pastoralism dominates, although extensive for 1.1 percent (6,376square kilometers) of Kenya. The areas are unused. Extensive smallholder farming is Transitional Wooded Grassland of Tanzania is more carried on in more favorable areas (Berry, Taurus, scatteredthanin Kenya,althoughitdoescoveralarger and Ford 1980). The pressure of use in this class is area-23,607 square kilometers, or 2.5 percent of the fairly light- EastAfrica 121

Class 33-Bushy Shrubland where else in EastAfrica. The "MontaneMoistForest" itself is dominated by Ocotea usanibarensisand Most Bushy Shrubland in the East African region oc- Podocarpusmilanjianus, among.other species. All of curs at elevations between 500meters and 1,000meters these zones fall within the boundaries of the Aberdare along the equator in Kenya, where it grows extensively National Park. on the lower eastern and southern slopes of the Central On the lower slopes of the-Aberdare Mountains, as Highlands, and to a lesser extent at lower elevations in well as the area covered by this class in the highlands the lower Tana Valley. Elsewhere, significant areas of southwestern Kenya, the vegetation is probably of exist on the eastern slopes of Mount Kilimanjaro and evergreen and semi-evergreen bushland, forming a in the highlands on the Tanzanian border, east of Lake transition between the montane vegetation above and Victoria. In all, this class accounts for 3.7 percent of Acacia-Cornrniphorabushland below. This transitional Kenya, an area of 21,552square kilometers. vegetation has been observed on a number of drier Elsewhere in the region, Bushy Shrubland is con- mountain slopes in East Africa, and is described more fined to Tanzania, where its distribution is more scat- fully in the section on East African Low Woody Bio- tered. Patches tend to occur within and around the mass Mosaic (Class 52). A similarvegetation occurs onI areas of Moist Acacia-CormiphoraBushland and the lower slopes of Mount Kilimanjaro, although the Thicket in central Tanzania, notably in Arusha, Kili- moister conditions here give rise to upland rain forest- manjaro, Tabora, and Tanga districts, with outliers in type vegetation at slightly higher altitudes (see Mbeya District on the eastern shore of Lake Rukwa. Coastal and Gallery Forest, Class 83). The area of Bushy Shrubland in Tanzania is 10,065 The remaining areas of Bushy Shrubland are rather square kilometers, 1.1 percent of the country. small, and scattered throughout the Moist Acacia- The large block of Bushy Shrubland in eastern CommiphoraBushland and Thicket (Class 43) of Tan- Kenya lies at the southern fringe of the. Semidesert zania. The vegetation in these areas is probably of the Wooded Grassland (Class 21), which dominates the scrub forest type, more open than the surrounding arid interior of the country. It is likely that this vege- bushlanid and thicket. A dense understory of 3 to 5 tation is intermediate between Semidesert Wooded meters height exists, dominated by Commiphoraspp., Grassland (Class 21) and Dry Acaca-Commiplora among others. The main emergents are Adansonia Bushland and Thicket (Class 41) in areas receiving digitataand Euphorbiaspp. annual rainfall between 200 and slightly less than 250 Land use in Class 33 is limited by the sparse and millimeters. Reaching only 2 to 3 meters in height, the seasonal rainfall. Grazing is of poor quality and the vegetation consists of small bushes and stunted trees, carrying capacity low. Given the small population of dominated by Acada reficiens ss. misera, forming a the areas of Class 33, little degradation of the biomnass sparse canopy over a ground layer of small shrubs. occurs. Regional growing stock is 34 million tonnes The grass cover is ephemeral, with annual species and sustainable yield is 1.7 milion tonnes a year. appearing only briefly after rain. The largest single area of this vegetation is in the Class 41-Dry Acacia-Commiphora Bushland Aberdare Mountains of south Kenya, mostly concen- and Thicket trated around the lower eastern slopes but attaining higher altitudes. The recording of Bushy Shrubland at This class is most characteristic of Kenya, of which it such altitudes may result from amalgamation of a covers 36.4 percent (214,312square kilometers). Dom- wide variety of montane vegetation types, ranging inating the eastern third of Kenya, it also extends west from heatliland to forest, an artifact of the coarse spa-' along the north of the CentraLHighlands as far as tial resolution of the AVHRRimagery used in the study. Uganda, whereitcovers8,115squarekilometersinthe The Aberdare Mountains host a well-developed northeast of that country. In Tanzania, itis confined to montane vegetation, with the highest altitudes sup- the north, occurring mainly in Arusha and Shinyanga porting Afro-alpine communities characterized by districts. Considerable areas also exist as inclusions giant Seneciaand Lobeliaspecies. Farther down is the within the Moist Aacia-CommiphomiBushland and "Shrub and Moorland Zone," dominated by Ericaspp. Thicket (Class 43) of Tabora and Singida districts and Next comes the uppermost llayer. of the montane. in the border districts of Tanga and Kilimarjaro. Dry rainforest belt, the"Hagenia-HypericumZone,"consist- Acaca-CommiphoraBushland and Thicket covers ing of vegetation stands between 9 and 15 meters in 36,044square kilometers in Tanzania, 3.9 percent of height, dominated by ageniaabyssmica and Hypenium the country. rewlutum. The middle of the forest zone is character- Values of NDviare quite small and reflect the semi- ized by giant bamboo, Arundinariaalpina, which is annual rainy season (figure 12-1). Class 41 occurs at more extensive on the Aberdare Mountains than any- elevations between 200 and 1,000meters. 122 EslimntingWoody Biomnass in Sub-Sal arami Africa

Figure 12-1. NDVI Profiles, Bushland and Thicket addition to cutting for fuelwood. In consequence, (Classes 41 and 43) some degradation of the quality of the biomass occurs. Because the woody vegetation is often spiny, this 0.6- -41 Kcayaf - - vegetation class provides problems, both of access to - 41 Kenya 0.5- .. ... fuelwood and its use. Both the growing stock and -Central-43Tmwanh - - sustainable yield of the woody biomass resource are OA- - small, and considerable clearance for fuelwood and 5.3 < .- - - - / charcoal already has taken place-even in protected a 0.3- > /\ - / areas like Serengeti National Park. Although biomass *02- destruction by-elephants and other gamehas occurred 0.2/ \ / \ //in recent years, this problem is more serious in the 0.1- V - f bushlands of Kenya than in Tanzania.

a- * * a -T- . Class 43-MoistAcacia-Commiphora Jan Fcb Mar Apr May Jun Jul Aug Sep Oct Nov c Bushland and Thicket

This area coincides with Moore's "semidesert' cat- Moist Acacia-CommiphoraBushland and Thicket cov- egories (1971), being characterized by deciduous ers a large triangular area of central Tanzania, extend- bushland and thiket of markedly seasonal growth ing from Lake Victoria in the north almost as farsouth and extensive grassy plains with no woody vegeta- asLakeNyasa,andreadhingtheUsambaraM ountains lion. The bushland is dense, varyingbetween 3 and 5 in the east Elsewhere in Tanzania, outliers exist in the meters in height, with very occasional emergent trees southeast and around Lake Rukwa in the southwest, to 10 meters. Tree species are dominated by Acacia giving an area of 174,052square kilometers, or 18.8 spp.andCommphoraspp,orsatbush(Suaedamowoic), percent of the country. In Kenya, where Dry Acacda- in vegetation that has been described as 'Acacia- CommiphoraBushland and Thicket (Class41) predom- Commiphorathoom savanna" (Lucas 1968). mates, this moister variant grows in areas of greater However, studies of this vegetation class on the rainfall-notably along the coast and in the southen Serengeti Plain of northern Tanzania indicate a much and western highlands. greater dominance of grassland communities than Moist Acacia-CommiphoraBushland and Thicket is suchaname would suggest, especially on soilsformed much less extensive in Kenya than in Tanzania, cover- on young volcanic ash, hardpan soils, and black crack- ing only 6.6 percent of the country (38,836 square ing soils (mbuga).The grasses provide only 15 to 45 kilometers). Other important areas exist in central and percent ground cover and hees are rare, restricted to southern Rwanda (5,796square kilometers, or 30 per- Acaia melliferabushes on young volcanic ash. These cent of the country) and on the central plateau of secondary grassland communities are controlled by Burundi (2,319square kilometers, or 8.7 pErcentof the burning and, to a lesser extent, by browsing and graz- land area). ing. When the interval between burning increases be- Values of NDvi are invariably greater than those for yond 5 years, Acacia spp. are able to regenerate, be- Dry Acacia-CommiphoraBushland and Thicket (Class coming fire resistant 3 to 4 years later. 41) and reach OAduring the wet seasons (figure 1-1). The areas of "Acacia-Comnmiphormthorn savanna" In Tanzania, extensive areas of Class 43 occurbetween (Lucas 1968)are dominated by Acaciaspp., especially 1,000and 2,000meters, but the dlass also exists at low A. melif ua,A. seyal, and A. tortilis, and CoWJmiphora elevation on the Kenyan coastal plain. spp., especially C madagascariensisand C merkeri.In I.n Tanzania, the vegetation is mostly dense bush- Kenya, the transition to semidesert vegetation is land of 3 to 7 meters height, with occasional emergent marked by Acacia reficiensss. misera Other species trees to 20 meters, and is characteristic of the semiarid commonly indude Bosciaspp. and Grewmiaspp. The regions of the country. The trees are generally fire most common emergent trees include Adansonia resistant, with evergreen species making up only 2.5 digitataand Euphorbiaspp. Within the wooded areas, to 10 percent of the trees and shrubs. Grass cover is thegroundcoverisofscattered tussoclsofgrass,often thinner than in more open bushland, but may still dominated by Aristida spp., and occasionally reach a height of 1.5 meters. It is dominated by tall Sporobolus robustus. . Hyparrhenia spp. with shorter Panicum, Setaria, and Growing stock for the region is 359 million tonnes Thlemedaspecies. and sustainable yield is 55 million tonnes a year. The principal tree species are Acacia, notably A Migrant pastoralism is the dominant land use, with gernii, A hockii,A. mellifera,A. nilotica,A. seyal,and burning of grasses to encourage fresh, palatable A tortilis,and Commiphora,especially C. africna, C growth and, locally, concentrated browsing of trees, in cuenilea,C mollis,and C schimperi.Other common tree -EastAfrica 123 species include Adansonia digitata, Boscia coriacca, pylacantiha,A. hebecladoides,A. seyal ss. rnultijuga,and CadabafArinosa,Cadia spp., Delonixelata,Lannea spp., A.sieberana.Theareasof'WoodedSavanna"aredom- Sterculiaspp., and Terminaliaspp. A shrub layer also inated by ConbretumelaeagnifoliuM, and include Acacia exists, dominated by Combretum aculeatum,Greruia campylacantha,A. hebecladoides,and, more occasion- spp., and Maerunspp. These regions also contain suc- ally, Dombeyamadiensis and Gardeniajovis-tonantis. culents and climbers. In central Burundi, where this class also occurs, In areas where branches interlace and impede pas- most of the area is taken up by coffee, tea, and sage, a thicket is formed within the bushland. These tobacco cultivation. However, the vegetation also may be small patches around old termite mounds or may include Exothecaabyssinica savanna, replacing mayextendoverhundredsof square kilometers.Inthe the original humid forest, and Ericaceousand Afro- drier areas of Tanzania, thickets often are fully decid- alpine vegetation dominated by Agrostis spp., uous and contain a rich variety of plant species. The. Deschampsiaspp., Festucaspp., Koeeria spp., Pentas- best such example is the "Itigi Thicket" coverng 62.0 chistis spp., and Poa spp. square kilometers of the central plateau. The principal This is regionallyone of the more important produc- species here are Baphiamassaiensis, B. burttii, Bussea tive classes; growing stock is 378 million tonnes and massaiensis,and Pseudoprosopsisfischeri, forming a sustainable yield is 4.5 milliontonnes a year. dense thicket 3 to 6 meters in height, occasionally The greater precipitation associated with Class 43 broken by emergent evergreen and semi-evergreen allows a wider range of land uses than in Class 41. trees to 8 meters. Bush fallowing allows the regeneration of tree cover, Other species associations within the thicket in- butwithabiastowardfire-resistantspecies.Sedentary dlude taller stands of Crnibiabmvicaudata ss. burtii, agculture entails almost complete loss of trees, with Combretumtrothae, Grewia burtii, and Tapiphyllumflori- a tendency for deforestation to spread outward from bundumnOther important types of thicket include: settlements.

The "Commiphora-CordylaThickets"ofeasternTan- Class 51-Acacia Woodland Mosaic zania, dominated by Crotonspp., Hippocrateaspp., Lanneaspp., and Stnjchnosspp.- This class, which covers 3.4 percent of the region, is The "Commiphora-CordylaThickets" of central Tan- aLmostentirely restricted to Kenya (43,105square ki- rama, with species including Aacfa circummarginata, lometers) and Tanzania (18,970square kilometers). Commiphomaedea,Chombyi,Cn*ed,andConlyla In Kenya, the main occurrence is a large arc to the de flora south and east of the Central Highlands at an altitude * "EuphorbiaThicket' of about 1,000 meters, with Dry Acacia-Commiphora. * A thicket occurring on rockyhills that is dominated Bushland and Thicket (Class 41) adjacent to it at lower by Dalbergiaspp., Diospyrosspp., Dombeyaspp., altitudes. Another area forms an arc on the southem Markhamiaspp., Strychnosspp., and Tecleaspp. margin of Tsavo National Park The third Kenyan area is around the equator on the Somalian border. In drier upland areas, the transition between Moist Northern Tanzania has two main occurrences: an Acaci-CommiphoraBushland and Thicket and Mon- area running east-west around Arusha, and a smaller tane Forest (Class 84) is marked by an evergreen to arc on the eastern side of Serengeti National Park. semi-evergreen bushland 3 to 7 meters in height This Growingstock for this class is 138million tonnes, with rather dense vegetation is dominated by Acokanthera a sustainable yield 3.9 million tonnes a year. spp., Carissaedulis, Dodonaeaviscosa, Euclea spp., Olea Rainfallmay be as highas 750millimeters, but to the africana,Tarchonanthus camphoratus, and Tecea spp. south of Tsavo National Park and on the Kenya-Soma- The presence of this vegetation class around Lake lia border, it is below 500millimeters. These two areas Rukwa in southwestern Tanzania is the result of in Kenya nave two wet seasons, as does the main miombowoodland clearance. Repeated clearance for Kenyan area. The two areas in Tanzania have one wet cultivation here has led to a decline in the original season. miombospecies, which was replaced by fire-resistant . Land use has contributed significantly to the rhar- species common to Combrelum savanna, especially acteristics of the vegetation in much of the area, with Brachystegia spiciformis, Combretum mechowianum, pastoralism dominating in the drier areas, moreorless Diplorhynchuscondylocarpon, and Syzygiumguineense. intensive smallholder farming in moister areas, but In Rwanda, this class consists mostly of "Herba- with sections in Tanzania unused. Small parts of ceous Savanna," but also includes areas of "Wooded TsavoandSerengetinationalparkslieinthisclass.The Savanna," especially in the north (Am 1987).The 'Her- main modification to the biomass in Class 51 has been baceous Savanna" is dominated by T1emedatriandra, through clearance of trees for agriculture, grazing, but includes scattered individuals of Acacia cam- browsing, and buming of grassland. Considerable 124- Estirnalin,gWoodyBiomass in Snb-SalmomnAfrica tree cover,has been lost in the main Kenyan extent of Class 61-Open Woodland this class,so that cultivationand grazing land domi- nate except in the less-favorable areas of higher, Open Woodlandexists throughoutTanzania, where it steeper, rockier slopes. Charcoal buming also has occursas smallpatches scattered among larger blocks caused conversionto grassland(White 1983). of Seasonaland Wet MiomboWoodland (Classes66 Acaciaspp. dominate the tree cover of Class 51, with and 67) and Dry and Moist Acacia-ComndplworaBush- some Commiphornspp. Evergreen species such as Car- land and Thicket (Classes 41 and 43). Together these issa edulis, Dodonaeaviscosa, Euclez divinorunr, and E. blocks add up to an area of 21,025square kilometers, racemosamay be present, with a tendency for Acacia covering 2.3 percent of the country. The remainder of spp.to invade areas degraded by concentrated brows- this woodland exists in. Burundi with 1,212 square ing. Under severe browsing, woody plants may be kilometers along the northwestem border and in the absent or reduced to bushes, such as Bosciaspp. (White southeast This covers 4.5 percent of Burundi. 1983). South of Nairobi, cultivation and pastoralism The ratherrandom distribution of this vegetation in have completely removed the tree cover over exten- Tanzania makes accurate description difficult. It is sive areas. probably true that, inmany cases, the species structure of small patches of Open Woodland is similar to that Class 52-East African Low Woody Biomass of the surrounding vegetation, the major difference Mosaic being in density. In central Burundi, this class is prob- ably similar to the savanna already described under The East African Low Woody Biomass Mosaic covers MoistAcacia-CommiphoraBushland andThicket (Class much of the northeastem quarter of Uganda, extend- 43).fheextensiveareainnorthwestemBurundiincludes ing eastward over the highlands of southwestem expanse of "Wooded Savanna," dominated by Acacia Kenya. It is of considerable importance in. Uganda, albidaand A. gernrdii This region also includes 'Tatsi- coverng 13.7percent of the country, or 32,671square tional Rain Forest," containing Albfziaspp., Hyplaene kilometers. In Kenya, it occurs largely in inaccessible benguelns, and Nemtoniabudanuan (M'Hirit1986. highlands and covers 51,905square kilometers, or 8.8 Growing stock of Class 61 is 68.9million tonnes and percent of the country. The class is associated with a sustainable yield is 1.0 million tomes per year. 6-month dry season. In Uganda and Kenya, much of the mosaic is likely Class 65-Moist Sudanian Woodland to consist of "CombretumSmall Tree Savanna," domi- nated by C. binderanum,C gihasalense,C moalk,and C Moist Sudanian woodland in the East African region zeyheri, among others. In Uganda, this "Combretum is restricted to northern Uganda, where it forms the Small Tree Savanna" is combined with occurrences of eastern edge of a land cover belt extending as far west Acaciaspp. and Ahlbiziazygia and the "TerminaliaSa- as Mali It is classified by White (1983) as "Sudanian vanna" in the north of Uganda. This latter community Isoberliniaand Related Woodlands." This land cover is dorninatedbyT.glaucescensalongwithAlbiziazygia, class covers 15,334square kllometers (6.4 percent) of Combretummolle,and other deciduous species; itprob- Uganda. Climatically, the area has a dry season of ably is derived from denser woodland. about 6 months and annual precipitation of about In the highlands of southwestern Kenya, it is 1,000millimeters. likely that the natural vegetation in the mosaic con- The vegetation may be described as Open Wood- sists of evergreen and semi-evergreen bushland. landsavanna.Itseemstobeadegradedmiombowood- This vegetation type occurs on drier mountain land, although it does not possess either of the two slopes throughout East Africa, often as a transition genera most characteristic of miombo,Brachystegia and between "Montane Forest" (Class84) and Moist Acia- lulbernardia.There occurs, however, a single species in CommiphoraBushland and Thicket (Class 43). Al- each of the other two commonmiombogenera,Monotes though the species structure is rather variable, a num- and Uapaca.This class also is shorter than true miombo ber nearly always are present, including Acokantherm woodland,rarelyexceeding15metersinheightAtthe spp., Carissaedulis, Dodonaea viscosa, Euclea spp., Olea southern edge of the mnainIsoberlinia belt, including africana,Sanseuieria spp., Tarchonanthuscamphoratus, Uganda, Isoberliniadoka becomes more important, al- and Tecleaspp., as well as succulents such as Aloespp. though it is scattered. and Euphorbiaspp. Isoberliniaspp. have the ability to regrow from un- Smallholder cultivation with some pastoralism are derground suckers and thus are able to withstand fire. the dominant land uses, although the land is of poor An understory of climbers and shrubs maybe present, quaLityand little anthropogenic pressure threatens the with a herbaceous carpet of perennial grasses includ- biomass. Regiornalgrowing stock is 181 million tonnes ing Andropogonspp., Eragrostisspp., Pennisetumspp., and sustainable yield is 53 million tonnes a year. and Scdizachyriumspp. EasIAfnic' 125

To a considerable extent, the form of Class 65 has Figuire12-2. NDVI Profile, Seasonal MiomnboWood- been determined by human activity such as rotational land (Class 66) bush fallowing (which entails clearing and buming), sedentary smallholder cultivation, and grazing and. browsing by domestic animals. Because population densities are low, fuetwood is in.good supply. Grow- ing stock is 48 milUiontonnes and sustainable yield is O-4 just less than 1 million tonnes a year.

Class 66-Seasonal Miombo Woodland

Seasonal Miombo Woodland is very extensive in the . ___ west of Tanzania, where it occurs from Kagera in the north to Lake Malawi in the south, covering much of 0 the regions of Shinyanga, Kigoma, Tabora, Rukwa; Jan Fe MarApr MayJun 3,I A15 Sep OCNov Dee Mbeya, and Iringa. Large areas of Seasonal Miombo Woodland occur along escarpments flanking the Lake where mean annual rainfallexceeds 1,000millimeters, Tanganyika trough, with smaller fragments extending the Seasonal MiomboWoodland tends to be fairly wet north along the border with Rwanda and Burundi, and therefore floristically richer than drier miombo and into the extreme southwest of Uganda. In Burundi variants. Evergreen species are more common and itself, this class accounts for much of the northeastemr strips of riparian forest may develop around perma- and southern regions. nent streams. -Apartfromthenorthern ipofZar, themaiig The woodland canopy usually is between 15 and 20 areas of Seasonal Miombo Woodland are scattered meters in height, with dominant species including through Tanzania,especially along the border with Mo- Isoberliniiaangolensis, L panicuzata,and Tenninaliamollis. zambique, east of Lake Victona, in the Central High- AlsocommonareBrwchystegiaspp.,althoughtheiroccur- lands, and in the eastern districts of lindi and Pwani. rence varies with local conditions and mean annual Scattered outliers also exist witiin the Wet Miombo precipitation.Much of the SeasonalMiombo Woodland Woodland (Class67) of southeastern Tanzania. along the border with Mozambique also is rather wet, The figures for area and percentage cover of Sea- andinadditiontothespeciesjustmentioned,Julbemardia sonalMiomboWoodland are: Tanzania, 336,565square magnistiulatais comunon.Similarly, the former species kilometers (36.4 percent); Burundi, 10,855square kilo- also appear with Isaberliniatomentosa where Seasonal meters(40.6percent);Uganda,5,63Bsquarekilometers MiomboWoodland coincides with the greater rainfall (2.4 percent); and Rwanda, 2,10Bsquare kilometers areas of the eastern Plateau. (10.9 percent). Although slightly open, the woodlands just de- Values of NDVIreach 0.5 in the wet season and show scribed generally lack a shrub layer, having instead a the marked seasonality characteristic of these wood- ground layer of the grasses Andropogonspp. and Pani- lands (Millingtun and others 1989),with dry-season cum maximum, and saplings of the main tree species. minima of about 0.2 (figure 12-2). It is interesting to In Burundi, the principal species in this class are note the close similarity of the NDVI temporal profiles Brachystegqiaspp. and Maesopsisspp., reflecting the for SeasonalMiombo Woodland in Tanzania and Zaire transition toward forest vegetation. (figure 11-3).The dry season in this class lasts about 6 The largest block of Seasonal Miombo Woodland months. extends south from Lake Victoria to just north of Lake As White (1983)points out, "where climate changes Malawi It is drier than the Seasonal Mi,owboWood- rapidly, as on the escarpments flanking the Lake Tan- land on the western border of Tanzania and is siri- ganyika and Lake Malawi troughs ... ithas not always larly dominated by Brachystegiaspp. (notably B. boehmii been possible to map wetter and drier miombosepa- and B. spicifbnnis)and Julbernardiaglobiflora. However, rately." Much of this vegetation class is distributed on some species associated with dier vegetation also are the steeply sloping shores of Lake Tanganyika, along present,forexample,Acaciabreuispiaz,Acalyhafruticosa, the coast of Zanzibar, andas scattered patches in other Eucleadivinorum, Grewia bicolor,Lantana camami, Or- blocks of fairly uniform vegetation, suggesting that it mocarpumtrichocarpum, and Terminaliam&llis. In gen- often is a product of local conditions. Nonetheless, in eral, however, the woodlands are floristically poor, mnanycases it is possible to suggest a probable conpo- with the canopy rarely atining 15 meters. In espe- sition for this vegetation class. cially poor conditions, the canopy may be as low as 3 Along Lake Tanganyika and the border regions of meters; in such cases, it often is-dominated by Monotes Rwanda, Burundi, and southwestern Uganda, an area spp. and UapacakIrkiana. 126 l2sliintlingWoody Biornass in Snb-SalrnranAfrica

Regionally, this is one of the most significantclasses. shifting agriculture, especially near the south of Lake Growing stock is 1969 million tonnes and sustainable Tanganyika. Here a mosaic of woodland and cultiva- yield is 31.6 million tonnes a year. tion plots exists, where woodland is cleared and Human population density throughout Class 66 is burned prior to a cultivation cycle of 2 to 4 years. In a generally low, partly because tsetse limits the keeping study of the regrowth of abandoned cultivation plots of cattle. Bush fallowing entails some renewal of bio- in Zambia, Stomgaard (1985, 1986) identified three mass, but the intensity of land use is low and vegeta- successional stages in the regrowth of cleared miombo tion is substantially intact. Few problems exist with woodland: the fuelwood supply. 1. In the first year after cldeooice, crops still domi- nate, although plots are be, .ng to be invaded by Class 67-Wet Miombo Woodland shrubs especiallyEuphorta tincalli and Smilaxkwaus . 2. In the2 to 6 years afterclearance,furtherinvasion Wet Miombo Woodland dominates the large block of by shrub and grassspecies occurs. The woodyvegeta- woodland in.the southeast of Tanzania, which extends tion at this time is dominated by Euphorbiatirucalli and over a roughly triangular area from Tanga District in Smilaxlkaussiana.By the end of this phase, the ground the north to Lake Malawiand the Mozambique border cover is dominated by grasses, notably Rynchelytm in the south. Smaller patches are found in the western repens. half of the country, especially along Lake Tanganyika 3. From 6 to 25 years after clearance, the reinvasion and the borders with Rwanda and Burundi, and to the of woody species is sufficient to form a canopy wood- north and east of Lake Rukwa. In alL Wet Miombo land, although it usually lacks a shrub layer. Woodland cova..s 11.6 percent of Tanzania, an area of However, the original Bracdystegia-Julbernardia 106,919square kilometers. woodland is replaced by fire-resistant and fire-toler- Elsewhere, significant outliers occur in the north- ant trees of the "CombretumSavanna," most notably east and southwest of Rwanda (2,319square Idlome- Combretum mechowianum, Diplorhynchzus condylo- ters, or 12 percent), the southwestern corner of carpon,and Syzygiumguineense. The tree canopy en- Uganda (10,644square dilometers,or 4.5 percent), and ables Uapacaspp. to invade, and the main components to a much lesser extent in westem Burundi (1,844 of the Bramhystegia-ulbemnardiawoodland may reap- square kilometers, or 6.9 percent). In Tanzania, Wet pear toward the end of this stage Generally, however, Miombo Woodland is the equivalent at lower altitude the increasing pressure on land has shortened recov- of Seasonal MkiomboWoodland, with extensive areas ery time of abandoned plots, so the cultivation savanna below about 500 meters. is spreading at the expense of zionbowoodlands. Large areas of southeastem Tanzania covered by Thernemainingareas of WetMiomboWoodland have thisclasswerepreviouslylabeled"DryMiomboWood- a varied composition. Along the Tanzanua-Burundi land" (White 1983).However, the evergreen nature of border, this class appears in a fairly high rainfall area the entire vegetation community is more apparent at an altitude of more than 1,200 meters, indicating a here, and some areas appear to have virtually no moist type of montane forest vegetation. In this case, period without growth The woodland is dominated the dominant genera include Aningeria, Cassipourea, by Bnchystegia boehmi, B. spicifonnisjulbernardiaglobi- Chnrsophylum,Macaranga, Neoboutonia, Porinari, Poly- flom, and J. magnistipulata,formning a canopy that rdrely scias,andTabernaemontana. Shrub andherb layers tend exceeds 15 meters in height. to be fairly discrete and dominance among the tree In many eastern districts, including areas of tLe species is low. coastal lowlands, the Wet Miombo Woodland is In the moister climate of Rwanda, Wet Miombo probably derived from the 'Dry Lowland Evergreen Woodland often consists of dense stands of "Acacia Forest" that once may have covered wide expanses Savanna." The dominant species are A. campylacantha, of the eastern plateau (Polhill 1968). Hence, Wet A webweladoides,A. syal spp. multijuga,A. senegal,and MiomboWoodland contains a number of tree species A. sieberana,often with an understory of A seyaLIn the from this older vegetation community, notably southwest of Rwanda, extending down the westem Drdbergiaspp., Ostryodernis spp., Pleurostylia spp., side of Burundi, this class also is represented by Sclerocaryaspp., and Tamarindusspp. In the extreme "AcaciaSavarna," but the dominant species here are southeast, the Brachystegia-Julbernardiawoodlands A. albidaand A gerardii On the eastern edge of this are replaced by structurally similar woodlands zone, toward the wetter highlands of Burundi, the dominated by other leguminous tree species, espe- vegetation may take on the character of Open Wood- cially Dalbergiaspp., Lonchocarpusspp., and Millettia land (Class 61) rather than savanna, with Brachystegia spp. - spp. becoming more common (MHiit 1986). Some areas of Wet MiomboWoodland in the south- Growing stock for the region is 1,555million tonnes west of Tanzania have been affected by clearance for and sustainable yield is 16.2 million tonnes a year. EastAftrrca 127

Land use in the area of Wet Miombo Woodland There are fragments along the northem border of varies from sedentary smallholder cultivation in more Burundi and larger areas in north and central Rwanda. densely populated areas to extensive rotational fal- The class is important in both countries, covering 17.4 low. In general, few problems of overuse occur. percent (3,372square kilometers) uf Rwanda and 7.7 percent (2,055square kilometers) of Burundi. Class 71-Evergreen Woodland Mosaic The greater productivity of this class is confirmed by NDVI curves. An example from west Tanzania Despite its considerable extent, the Evergreen Wood- shows values consistently above 0.3, with no lengthy land Mosaic is difficult to describe due to its scattered dry season (figure 12-3). distribution. The area and percentage cover-in each In the Lake Victoria Basin, where virtually no dry country are: Tanzania, 23,291 square kilometers (2.5 season occurs, the mosaic is made up of wooded grass- percent); Kenya, 9,485 square kilometers (1.6percent); land with relics of the original peripheral "Guineo- Uganda, 1,423 square kilometers (0.6 percent); Congolian Forest" A description of this vegetation is Rwanda, 843 square kilometers (4.4 percent); and presented under the Forest classes (82,85,86, and 87). Burundi 790 square kilometers (3 percent). The-area to the north and west of Lake Victoria is the The carpet areas of Evergreen Wo,odland Mosaic largest area of anthropogenic savanna in the region, occur on the coast and up to about 500 meters altitude stretching from the humid areas near the Kakamega in northeastern Tanzania, scattered within larger Forest in Kenya around the lake through southem blocks of vegetation, especially the Miombo Wood- Uganda, and into the northwest of Tanzania. lands (Classes 66 and 67). This mosaic frequently ex- Near Dares Salaam, the mosaic is similar to the East ists in mountainous areas and near lakes. African Low Woody Biomass Mosaic (Class 52) de- The word "evergreen" in the class name needs tobe scribed for the same area. However, both this area and qualified because the tree species in this vegetation, those on Zanzibar probably have suffered more deg- mainly common miombospecies such as Brachystegia radation due to ovenise than the high woody biomass spp., Isoberliniaspp., and Julbemardiaspp., are deddu- mosaics such as those typified by this class. Con- ous. The evergreen nature of the woodland mosaic versdly, the woodland patches within the High appears to result from an evergreen understory that is Woody Biomass Mosaic in Tanga District probably recorded by the AVwRRsensor whether or not the can- consist of Wet MiomboWoodland (Class 67), the pnin- opytree species are inleaf. This suggests smallpatches cipal species being Brachystegiabohmii, B. spiciformis, of vegetation with a tree flora similar to the surround- Julbernardiaglobiflora, and J. magnistipulata,and possi- ing woodland, but with a lush understory resualting bly older forest remnants (see Class 67). from favorable local conditions. These conditions un- In Rwanda, the mosaic area in the north includes doubtedly are related to moisture availability, as indi- "Montane Forest" and "Wooded Savanna with Forest cated by the more humid climate of lakeside and Regrowth" (AID1987). The "Montane Forests" are mountainous locations. characterized by Podocarpususambarensis and Syzyg- Growingstockinthisclassisl&3miUiontonnesand ium paruifolium,among other species. The open areas sustainaole yield is 680,000 tonnes per-year. Popula- of the mosaic consist of "Wooded CombretumeLaeag- tion density is relatively sparse and no senous short- nifoliurnSavanna," includingAcacia spp. In southeast- age of fuelwood exists at present. ern Rwanda, and across the border into Burundi, this

Class 72-Cultivation and Forest/Woodland Mosaic Figure 12-3. NoVI Profiles, High Woody Biomass Mosaic (Classes 72 and 73) This land cover class occurs between sea level and 2,000 meters altitude in all five countries of the East 0-6- African region. In Kenya and Uganda, it is restrcted to the Lake Victoria Basin, where much of the original -- rain forest hasbeen deared for cultivation. The mosaic OA- covers 2.9 percent (6,850 square kilometers) of - Uganda,butonlyO.3percent(2O02squarekilometers) a 0.3- of Kenya. Z In Tanzaia, blocks exist around Lake Victoria, es- 02 peially to the west, and on the coast around Dar es o - 72 WesternTanzmia SalaanL The area covered is 9,327 square kilometers, 73 Was Ug:mda or 1 percent of the cou,ntry.The mosaic also occurs on 0 i I I I the eastern side of Zanzibar. Jan Feb Mar Apr May Jun JUl Aug Sep Oct Nov Dec 128 EstimatinigWoody Biomass ifn Stb-Saulwnmi Africa class consists largely of "BradcystegiaWooded Savanna" western Uganda (figure 12-3). These relatively large and areas of "Gallery Forest." In Buyenzi and values indicate both the ability of the remaining tree Mugamba districts in northem Burundi, this class con- species to "green up" in response to the wet-season tains "Ombrophilous Mountain Forest," with Albizia conditions and the growth of crops within this mosaic. gummifera,Prunus africana,Polyscias spp., and Sympi1on- Growing stock is 101 million tonnes and sustain- nia spp. The associated altimontane prairies are dom- able yield is 1.1 million tonnes per year. Fuelwood mated by Agrostis spp. and Erica spp. supplies will become more difficult to obtain as This class is to a large extent the product of defores- forest is removed for agriculture. tation for smallholder settlement, either as rotational fallow, or increasingly for permanent settlement As Class 74-Guinean Woodland population increases, it is likely that the woody blo- mass in this class will be further reduced. In the East African region, Guinean Woodland is re- Crowing stock for Class 72 is 40 million tonnes and etricted to Uganda, where it occupies much of the sustainable yield is 448,000 tonnes per year. The fuel- northwestern sector of the country. It is similar to the wood supply is threatened by the removal of wood- "ComnbretumSmall-Tree Savanna" that grows exten- land as agriculture is extendet. sively over East Africa. This is characterized by a number of broad-leaved Combretinm species, notably Class 73-Cultivation and Forest Regrowth C. binderanum,C ghiasalenlse,C. miolle,and C. zeyheri,In Mosaic Uganda, however, the Combretum savanna combines with Acacia spp. and Albizia zygia. In wetter areas of Cultivation and Forest Regrowth Mosaic occurs ex- Uganda, the vegetation also contains Terminalia mollis tensively around the north of the Lake Victoria and T. glaucescens, replaced by the- smaller-leaved T. Basin, from central and western Uganda to south- brownii in drier regions (Trapnell and Langdale- western Kenya. It covers 18 percent (43,105 square Brown 1972). In northem Uganda, the Coombretutmspe- kilometers) of Uganda and 2.9 percent (16,915 cies are replaced by Butyrospennuim paradoxtrn ss. square kilometers) of Kenya. Regional growing niloticum. stock is 101 million tonnes and sustainable yield is Generally, the trees of the savanna are rather scat- 1.1 million tonnes a year. tered, reaching about 5 to 10 meters in height. They Some uncultivated area of this mosaic includes grow in a sea of tall perennial grasses of I to 2 meters, Guinean Woodland (Class 74), described in the next often dominated by Hyparrhenia spp. Guinean Wood- section. However, this land cover class is most exten- land covers 7.9 percent of Uganda, an area of 18,918 sive on the northern fringe of the degraded "Periph- square kilometers. eral Guineo-Congolian Humid Tropical Forests" Growing stock in Class 74 is 35 million tonnes and north of Lake Victoria Therefore, small areas of sec- sustainable yield is 394,000 tonnes per year. Because ondary forestregrowthmightbe expected onformerly the population is relatively low, no fuelwood short- cultivated land. As an example of forest regrowth in age exists yet the drier and floristically poorer margins of the Guineo-Congolian rain forest belt, the following de- Class 82-Evergreen Forest scription is adapted from White's account (1983) of the invasion of secondary wooded grassland by forest Evergreen Forest is scattered throughout the region species at Olokemeji in Nigeria. and, with the exception of some coastal areas of Tan- After 6 years without fire, the site had been invaded zania, occurs in highland areas between 1,000 and by Antiaris toxicara, Ceiba pentandra, Celtis brownii, 2,000 meters. Generally, it occurs along the Lake Tan- Diospyros mespil4bnnis, Hildegardiabaterh Holarrhenaflo- ganyika escarpment in the highlands of north Tanza- ribunda, MAlacanthaalnifolia, Manilkara obovata,and nia and south Kenya, and in the highlands and coastal Zantl}oxylum xanthoxyloides. After another 25 years, a areas of southeem and eastern Tanzania between Lake canopy 8 to 11 meters tall had formed, dominated by Malawi, the Mozambican border, and Tanga District. forest species such as Afzelia africana, Diospyros The area and percentage cover for each country are: mespilMbmis,Hildegardia barter, and Manilkaraobovata. Tanzania, 109,97Tsquare kilometers (119 percent); Even so, more than a dozen savanna species still Kenya, 6,580 square kilometers (1.2 percent); Burundi, persisted. However, the pressure on agricultural land 5,111 square kilometers (19.1 percent); Uganda, 3,056 in Uganda makes it unlikely that succession would square kilometers (13 percent); and Rwanda, 2,846 be allowed to continue undisturbed for such a long square kilometers (14.7 percent). This is one of the period. most significant classes for woody biomass. The rDmvcurve shows values in excess of 0.5 for the Itisdifficultto describeatypicalvegetation for such wet season but reduces to 0.2 in January for a site in a wide-ranging group of montane forest areas, given EastAfrica 129 the diversity of Afromontane vegetation. It is de- Andropogonspp., Hyparrheniaspp., Pennisetuin spp., scribed for a number of these areas by Lucas (1968), and Setariaspp. In the "Heathland" and "Afro-alpine" Osmaston (1968), and Polhill (1968). The following zones, the most common genera in secondary.grass- generally describes Afromontane vegetation types in land are.Agrostis,Descl)ampsia, Festuca, and Pon. the region. Along the coast of Tanzania, the Evergreen Forest Afromontane rain forests grow in a fairly wide class is probably derived from the "Dry Lowland Ev- range of local conditions, but rainfall generally ex- ergreen Forest" that formerly covered much of the ceeds 1,250 millimeters-a year, and often is more than coastal plateau. The vegetation consists of Brchy- 2,500 millimeters. Most forest lies between 1,200 and stegia-Julbernardiamiombo woodland containing a 2,500 meters altitude, although this too is variable. number of forest species from the old lowland forest. Typical tree species include Aningeriaadolfi-friedericii, It is more fully described under Wet Miombo Wood- Ocotea usambarensis, Olea capensis, Parinari excelsa, land (Cass 67). Podocarpuslatifolius, Prs afiraa, Syzygiumguineense The likelihood that fast-disappearing forest will be ss. aftomontanumn,and TabrnaeronUtnajolrnstonii. protected by law makes this class an unprom-Lising "Afromontane Bamboo" (Arundinaria alpina) is source of fueL In fact, much of the Evergreen Forest widespread in the highlands of East Africa. Occurring exists in protected areas, including the Mount Kenya mostly between 2,380 and 3,000 meters, it is extensive and Nairobi national parks in Kenya, the Ruwenzori on the Aberdare Mountains and Mount Kenya, and on National Park in Uganda, and the Kilimanjaro Forest the gentler slopes of the Ruwenzori Mountains. It is Reserve in Tanzania. Those areas lacking protection almost absent on Mount Kilimanjaro. Tree species are rapidly being cleared forsmallholdings. scattered among the bamboo include Dombeya Growing stock in Class 82 is 767million tonnes and goelzenii,Hageniaabysnica,lexmitfis,uniperusprocera, sustainable yield is 64 million tonnes per year. The Nuii congesta, Podocarpuslatifolius, Prunus africana, fuelwood supply is likely to become a problem in and Tabernaemontanajohnstonii. areas being cleared for agriculture. The phenology for this vegetationdclassshows con- sistentlyhighvaluesof mvi (aboveO.4)andno marked Class 83-Coastal and Gallery Forest seasonality (figure 124). Another feature of most high mountains, and the Coastal and Gallery Forest is most extensive along the summits of many smaller mountains, is "Evergreen Kenyan coast, although significant areas are dotted Bushland and Thicket"-particular.y near the coast along the northem coast of Tanzania. Elsewhere, and large lakes (White 1983). Unburned thicket often smaller areas are on Mount Kilimanjaro and in the is between 3 and 13 meters tall, and typical genera Cater Highlands and west Usambara Mountains of include Blaeria,Erica, Philippia, and Vaccinium. The northern Tanzania. This class accounts for 1.8 percent most extensive vegetation in the mountains.of East of Kenya (10,539square kilometers) and 0.6 percent of Africa is, however, grassland; the vast majority of it is Tanzania (5,586square kilometers). secondary, resulting from destructive human activity. The southernmost block of this forest lies between Secondary grassland in the montane forest belt typi- Kisii and Kilwa Kivinje, in the Tanzanian district of cally includes Exothe abyssinica,Loudetia simplex, The- Pwani. Here, the forest is made up of extensive stands medafriadra, and anumber of other species including of mangrove. The main genera are Avicenniaspp. and Rhizophonrspp.., although distinct mangrove zones have developed along the East African coast, and Figure 12-4. NDVI Profile, Evergreen Forest other. species, especially Bnouiena gnarrhiza and (Class 82) Heritier littoralis,also are presenL Along the coast of Kenya and northern Tanzania, as 0.6- far south as Dar es Salaam, this class is a mosaic of "Moist Forest" with "Transitional Evergreen Bush- land and Scrub Forest.' This is a diverse forest vege- 0.4- tation, its 15 to 20-meter canopy composed mainly of Afzelia quanzensis and Erythna sacuxii. Emergent 3 03o- species, some reaching 30 to 35 meters, include Albizia z adiantholia, Balaniteswilsoniman, Combretum scizuman- 022 - - niiJulbernardiamagnistipulata, Lannea spp., and AUml- The coastal fringe of the mosaic, 82 Ugmda especiallykara sansibarensis. along the northern Kenyan coast, consists 0.- * ofmangroveswampdominabedbyAvicenniaspp.and Jan Feb Mar Apr May Jun Jl Aug S Oept Nov Dec Rhizphora spp. 130 EstimatingWoody Biamanss in Sub-Snlhran Arica

In the remaining mountainous regions, the gallery Class 84-Montane Forest; Class 86-. forest component of this class covers small areas at Humid Tropical Swamp Forest; Class 87- high altitudes.The greaterrainfall of Mount Kiliman- Ombrophilous Humid Tropical Forest jaro and the Crater Highlands gives rise to "Upland Rain Forest," dominated by Aningeria spp., Parinari Much of this region's forested area is concentrated spp., and Ocoteaspp., together with Cassipoureaspp., around the northem and western shores of Lake Vic- Ckrysophylhumspp., Macarangaspp., Neoboutoniaspp., toria, in southem Uganda. Much smaller areas exist in Podocarpusspp., Polysciasspp., and Tabemaemontmna the north of Uganda and in the highlands of Kenya spp. A similar vegetation community could be ex- and noriern Tanzania. Ombrophilous Humid Tropi- pected for this class on the slopes of the Usambara cal Forest (Class 87) is the most extensive of the forest Mountains in Tanga District, although here it proba- classes, covering 33,145 square kdlometers (IBA per- bly merges with "Moist Lowland Forest," containing cent) of Uganda, 3,531square kilometers (0.6 percent) genera such as Allanblackiaspp., Cephalosphaermspp., of Kenya, and 1,370square kilometers (0.2 percent) of Isoberlinia spp., and Newtonia spp. Tanzania. Growing stock in Class 83 is 145.5 million tonnes Two otherrelated classes, MontaneForest (Class84) and sustainable yield is 8.1 million tonnes per year. and Humid Tropical Swamp Forest (Class 86), are far The fuelwood supply is good generally, although smaller, with an area of less than 6,000 square kldome- mangrovecuttingiscausingundesirableenviroranen- ters for the entire region. Because of the difficulty in tal effects in the coastal zone. distinguishing among these three forest types, the following descrption covers all three classes. Class 85-Mesophilous Humid Tropical Forest The area around Lake Victoria has been extensively cultivated, so the forests of south Uganda exist, for the This landcovercass occurs alongthenorthernmargin most part, in a mosaic with other vegetation and crop- of Lake Victoria in an area thathas no dry season. Most land. This taes the form of a grassland about 2 meters of the class occurs in Uganda, where the area of 13,490 talL with a varying density of fire-resistant-trees. The square kilometers constitutes 5.6 percent of the coLu. prncipal gasses indude Andropogonspp., Hyparrhenia try. Hereitprobablyrepresents White's"DrierPeriph- spp., and Loudetiaspp. Tree species include Burkea eral Semi-Evergreen Guineo-Congolan Rain Forest" africana, Combretum collinum, Strydmos spp., and Ter- (1983).Ablockof MesophilousHumidTropicalForest minalia spp. lies in the extreme southwest of Uganda, extending This region is at the easten edge of the "Guineo- into both Tanzania and Rwanda. This is an area of CongolianRainForest"zoneandisthusadriervariant highlands exceeding 1,400meters in elevation, with a of this rain forest type, containing most of the import- vegetation similar to that of the Wet Miombo Wood- ant species. The domninanttrees include Albizia spp., land (Class 67) on the Burundi border-that is, domi- Aningeria altissima, Celtis spp., Chrysophyllum albidum, nated by Aningeria spp., Parinarispp., and Ocoteaspp. Entandrophragmaspp., and Khayaspp. At the upper limit other genera tend to dominate, The shores of Lake Victoria host extensive swamp notably Hagenia spp., Myrica spp-, N?Jia spp-, and forests. Around the mouth of the Kagera River on the Rapaneaspp., especially on soil derived from volcanic westernshore,thesearedominatedbyBai!aeainsignis rock (emini-i)and Podocarpusfakatus.Western Uganda also hn Kenya, this class makes up a single block of 843 contains forest dominated by Parinariexcelsa. Another squarekilometers,correspondingimparttoKakamega important group of forests in this region are those Forest on the Nandi escarpment east of Lake Victoria. dominated by Cdtis spp., especaly C. mildbraedii, The forest contains both lowland species (includ- with a variety of other species. Related forests in the ing Aningeria altissima, Cordia millenii, En tan- Mount Kenya area are dominated by Newtonia bucha- drophragma angalense, Maesopsis enunii, and Monodora nanii In Tanzarua, forests mapped in this class include myristica) and Afromontane speces (sudh as Apodytes Allanblacktastuhlmannii and soberlinia scheffleri, with dimidiata, Macaranga kilimandscharica,Neoboutonia Newtonia spp. and Parinari spp. macrocalyx,Prunus aficana, Strombosiascheflri, and The montane forests of East Africa mapped in Class Turraeaholstit). 84haveavarietyof dominantspecies,Aningeriaadolfi- A number of types of land use occur in this class: friedericii, Entandrophragma excelsum, Ocotea permanent smallholdings, rotational fallow, and usambarensis, and Podocarpus mlanjinus being the mixed farming. Considerable areas of the forest have most commonu Kenya hosts some related forests that been cleared for agriculture; this threatens the long- indudeAlbizia spp., Polysciasspp.,and Oleaweluitschii term fuelwood supply. Growing stock of Class 85 is as dominants. A general description of the Afromont- 183.1 million tonnes and the sustainable yield is 21.8 ane vegetation in the region is in the Evergreen Forest million tomnes per year. (CIass 82) section. EastAfrica 131

In Lake Victoria Basin, a few fragments remain of Berry, L., T. Taurus, and R. Ford. 1980. East Africa the "scrub Forest" that once covered much of the Country Profiles-Somalia. Worcester, Mass.: Clark area. These relicts exist in south Uganda, notably University, Program for International Development. around Lake Edward, and in Burundi. Scrub forest Lucas, G. L. 1968. "Kenya." In I. Hedberg and 0. usually is dominated by Euphorbiadawei, forming a Hedberg, eds., "Conservation of Vegetation in canopy 12 to 15 meters in height. Often associated Africa South of the Sahara." Acta Phytogeographca with this canopy is Cynometra alexandri, a canopy Suecica54:152-66. and emergent species oi rain forests that here rarely M'Hirit, 0. 1986. Besoins en mati&red'education et de exceeds 10 meters in height. formationforesthereauBurundi.R6sum6nintroductoire A common characteristic of these three high- &la reunion dela commission tripartite. Rome:FAo. biomass classes is that they are threatened by exploi- Moore, J. E 1971. "Vegetation." In L. Berry, ed., Tan- tation for cultivation and this jeopardizes the fuel- zania in Maps.London: English Universities Press. wood supply, particularly in Uganda. The growing Morgan, W. T. W. 1973.EastAfrica. London: Longman. stock of Class 87, which is the most extensive of the Osmaston, H. A. 1968. "Uganda." In L.Hedberg and three classes, is 399-million tonnes. The sustainable 0. Hedber& eds., "Conservation of Vegetation in yield is 56.3 million tonnes. Africa South of the Sahara." Acta Phytogeographica Suecica54t148-52. Land Cover Class Tables Polhill, Ri 1968. "'Tanzania." In I. Hedberg and 0. Hedberg, eds., "Conservation of Vegetation in Af- Tables 12-1through 12-5,beginning on page 132,pres- ricaSouth ofthe SahaxamAcfaPhytogeographicaSueecs ent summaries for each land cover class of the area, 54:166-79. showing stock and sustainable yield for the Stomgaard, Peter. 1985. "Biomass, Growth and Bum- EastAfricannationsofBurundLKenya,Rwanda,Tan- ing of Woodland in a Shifting Cultivation Area of zania, and Uganda. South Central Africa." Forest Ecologyand Manage- ment 12163-78. References Stomgaard, Peter. 1986. "Early Secondary Succession in Abandoned Shifting Cultivator's Plots in the Every effort has been made to facilitate access to the Miombo of South Central Africa." Biotropica18(2): documents listed here. Some-documents, however, 97-106. lack full bibliographic information because it was Trapnell,C. G.,andL Langdale-Brown. 1972."Natural unavailable; also, some documents are of limited Vegetation.' In W. T. W.Morgan, ed., EastAfrica, Its circulation. PeopleSand Resources. Rev. ed. Nairobi: Oxford Uni- versity Press. Am (U.S.Agency for InternationalDevelopment). 1987. White, F. 1983. "The Vegetation of Afric" Natural "Draft Environmental Profile on Rwanda." AD Of- ResourcesResearch Senes 20. Paris: UNEscO/AETAT/ fice of Forestry, Enviromnent and Natural Re- uNso (United Nations EducationaL Scientific and sources, RSSA A/TOA 1-77. Prepared in cooperation CultulOrgae zation/Associationpourl'EtudeTaxo- with U.S. Man and Biosphere (MAB) Program of the nomique de la Flore de l'Afrique Tropicale/United Department of State. Nations Sudano-Sahelian Office). 132 Estimiting WoodyBiomrass in Slub-Satlaran Africn

Table 12-1 Land Cover Classes-Burundi (East Afdca Region) Area Gro'wingstock Sustainableyield Thousand Thloutsandtonnes Lantdcover clas kSn Percent tonines Percent peryear Percnt 24 685 2.56 42.47 0.03 6.85 0.17 2 685 2.56 42.47 0.03 6.85 0.17 43 2,319 8.66 3,923.75 3.14 48.70 1.23 4 2,319 8.66 - 3,923.75 3.14 48.70 1.23 61 1,212 4.53 3,563.28 2.85 53.33 1.35. 66 10,855 40.55 60,38636 48.36 966.09 24.48 67 1,844 6.89 21,943.60 17.57 245.25 6.22 6 13,911 51.97 85,893.24 68.78 1,264.67 32.05 71 709 2.95 405.27 0.32 15.01 0.38 72 2,055 7.68 3,460.62 2.77 39.05 0.99 7 2,845 10.63 3,865.9 3.09 54.06 1.37 82 5,111 19.09 30,666.00 24.56 2,545.28 64.50 83 53 0.20 470.53 0.38 26.39 0.67 8 5,164 19.29 31,136.53 24.94 2,571.67 65.17 Lakes 1,844 6.89 0.00 0.00 0.00 O.0 Total 26,768 100.00 124,861.89 100.00 3,945.95 100.DO (Percentage of region) (1.49) (1.93) (1.72) Note: In the followingtables, details may not add to totalsbecause of rounding. SourcmAuthors' calculationsfrom data bases derivedfrom land coverclassification and tabWe4-L

Table 12-2. Land Cover Classes-Kenya (East Africa Region) Area Growingstock Sustainableyield Thousand Thousandtonnes Landcover class km2 Percent tonnes Percent per year Percent 0 14,439 2.45 0.00 0.00 0.00 0.00 11 2,002 0.34 454.45 0.05 20.02 0.06 1 2,002 0.34 454.45 0.05 20.02 0.06 21 104,600 17.74 34,518.00 3.68 1,046.00 3.34 22 1,001 0.17 330.33 0.04 10.01 0.03 24 6,376 1.08 395.31 0.04 63.76 0.20 25 3,320 0.56 1,095.60 0.12 33.20 0.11 2 115,297 19.55 36,339.24 3.88 1,152.97 3.68 31 1,528 0.26 1,306.44 0.14 76A0 0.24 33 21,552 3.66 21,552.00 Z29 1,077.60 3.44 3 23,080 3.92 22,85B.44 2.43 1,154.00 3.68 41 214,312 36.35 297,893.68 31.72 4,500.55 14.35 42 211 0.04 390.56 0.04 4.43 0.01 43 38,836 6.59 65,710.51 7.00 815.56 2.60 44 316 0.05 44.56 0.00 11.06 0.04 45 6,271 1.06 11,607.62 1.24 131.69 0.42 4 259,946 44.09 375,646.93 40.00 5,463.29 17.42 51 43,105 731 96,12415 10.23 2,715.62 8.66 52 51,905 8.80 111,595.75 11.8 3,270.01 10.43 5 95,010 16.11 207,719.90 22.11 5,985.63 19.09

(Tabl coninueson thefollowingpage.) East Africa 133

.Table 12-2 (continwed) Area Grawingstock Sustinmableyield T7housand Thousandtonnes Landcover class km2 Perment totnes Percent peryear Percent 61 580 0.10 1,705.20 0.18 2552 0.08 64 2,055 0.35 5,486.85 0.58 94.53 0.30 65 1,475 025 3,93825 0.42 70.80 0.23 66 4,479 0.76 24,916.68 2.65 398.63 127 67 685 0.12 8,151.50 0.87 91.12 0.29 6 9,274 1.57 44,198.48 4.70 680.59 2.17 71 9,485 1.61 4,865.81 0.52 180.22 0.57 72 2,002 0.34 3,37137 0.36 38.04 0.12 73 16,915 2.87 28,484.86 3.03 321.38 1.02 74 1,844 0.31 3,105.30 0.33 35.04 0.11 7 30,246 5.13 -39,827.33 4.24 574.67 1.83 82 6,850 1.16 41,100.00 4.38 3,411.30 10.88 83 10,539 1.79 93,565.24 9.96 5,248.42 16.74 84 3,004 0.51 29,739.60 3.17 1,192.59 3.80 85 843 0.14 10,771.85 1.15 1,247.64 3398 87 3,531 0.60 37,036.66 3.94 5,225.88 16.67 -8 24,767 4.20 212,213.35 22.59 16,325.83 52.06 Lakes 15,545 2.64 0.00 0.00 0.00 O.oW Total 589,606 100.00 939,258.13 100.00 31,357.00 100.00 (Percentage of region) (32.78) (14.50) (13.69) Source?Authos' calculationsfrom data base derivedfrom land er classifation and able4-1.

Table 12-3. Land Cover Classes-Rwanda (East Africa Region) Area Growingstock Suistafivubleyiedd Thousand Thfousandtonnes Lanidcover clas km Percent tonines Percent per year Percenzt

24 158 -- 0.82 9.80 0.01 1.58 0.07 2 158 0.82 9.80 0.01 1.58 0.07 42 105 0.54 194.35 or27 221 0.10 43 5,796 29.97 9,806.83 13.14 121.72 5.72 4 5,901 30.51 10,001.18 13.68 123.93 5.82 61 211 1.09 620.34 0.85 9.28 0.44 66 2,108 10.90 11,726.80 16.03 187.61 8.82 67 .2,319 11.99 27,596.10 37.73 .308.43 14.49 6 4,638 23.98 39,943.24. 54.61 505.32 23.74 71 843 436 432.46 059 16.02 0.75 72 3,372 17.44 5,678.45 7.76 .64.07 3-01 7 4,215 21.80 6,110.91 8.35 80.08 3.76 82 2,846 14.72 17,076.00 1,417.31 6660 8 2,846 14.72 17,076.00 23.35 1,417.31 66.60 Lakes 1,581 8.18 0.00 0.00 0.00 0.00 Total 19,339 100.00 73,141.13 100.00 2,128.22 100.00 (Percentage of region) (1.0) (1.13) (0.93) Sourcc Authoraecalculations from dababasesderived from lndcover classification and table 4-1. 134 EstimatingWoody Biomass in Sub-SahqranAfrica

Table 12-4. Land Cover Classes-Tanzania (East Africa Region) Area Growingstock Sustainableyield Thousand -7tousand tonnes Landcover class knt Percent tonnes Percent per year Percent 0 474 0.05 0.00 0.00 0.00 0.00 11 3,952 0.43 897.10 0.02 39.52 0.04 14 105 0.01 23.84 0.00 1.05 0.00 1 4,057 0.44 920.94 0.02 40.57 0.04 24 23,607 - 2.56 1,463.63 0.03 236.07 0.21 25 105 0.01 34.65 0.00 1.05 0.00 2 -23,712 2.57 1A498.28 0.03 237.12 0.21 33 10,065 1.09 10,065.00 0.23 50325 0.45 3 10,065 1.09 10,065.00 0.23 503.25 0.45 41 36,044 3.90 50,101.16 1.15 756.92 0.68 42 158 - 0.02 292.46 0.01 3.32 0.00 43 174,052 18.84 294,495.98 6.75 3,655.09 3.27 4 210,254 22.76 344,889.60 7.91 4,415.33 3.95 51 18,970 2.05 42,303.10 0.97 1,195.11 1.07 5 18,970 2.05 42,303.10 0.97 1,195.11 1.07 61 21,025 2.28 61,81350 1.42 925.10 0.83 65 1,212 0.13 3,23604 0.07 58.18 0.05 66 336,565 36A3 1,872,311.09 42.93 29,954.28 26.81 67 106,919 11.57 1,272,336.10- 29.18 14,220.23 12.73 6 465,721 50.41 3,209,696.73 73.60 45,157.79 40.41 71 23,291 2.52 11,948.28 0.27 442.53 0.40 72 9,327 1.01 15,706.67 036 177.21 0.16 7 32,618 353 27,654.95 0.63 619.74 0.55 82 109,975 11.90 659,850.00 15.13 54,767.55 49.01 83 5,586 0.60 49,592.51 1.14 2,781.83 2.49 87 1,370 0.15 14,369.93 0.33 2,027.60 1.81 8 116,931 12.65 723,812.44 16.60 59,576.98 53.31 Lakes 41,050 4.44 0.00 0.00 0.00 0.00 Total 923,852 100.00 4,360,841.05 100.OD 111,745.89 100.00 (Percentage of region) (51.36) (67.30) (48.80) -Sour= Authors'calulations fromdata basesderived from land coverclassication and table4-1. EastAfrica 135

Table 12-5. Land CoverClasses-Uganda (East AfricaRegion) Area CroWingstock Suistainableyield Thouisand .. 7Thousandtonnes Lanidcover class k,n Percent tunnes Percent peryear Percent 23 Z,213 0.93 730.29 0.07 22.13 0.03 24 105 0.04 6.51 0.00 1.05 0.00 25 738 0.31 243.54 0.02 7.38 0.01 2 3,056 1.28 980.34 0.09 30.56 0.04 33 1,317 055 1,317.00 0.13 65.85 0.08 3 1,317 0.55 .1,317.0 0.13 65.85. 0.08 41 8,115 3.39 11,279.85 1.15 170.42 0.21 42 527 0.22 975.48 0.10 11.07 0.01 43 2,213 0.93 3,744.40 0.38 46.4? 0.06 45 84 0.35 1,560.39 0.16 . 17.70 0.02 4 11,698 4.89 17,560.12 1.79 245.66 0.31

.51 .263 0.11 586A49 0.06 16.57 0.02 52 32,671 13.67 70,242.65 7.16 2,058.27 2.58 5 32,934 13.78 70,829.14 7.22 2,074.84 2.60 61 422 0.18 1,240.68 0.13 18.57 0.02 62 158 0.07 421.86 0.04 12.17 0.02 64 263 . 0.11 702.21 0.07 12.10 0.02 65 15,334 6.41 40,941.78 4.17 736.03 0.92 66 5,638 2.36 31,364.19 3.20 501.78 0.63 67 10,644 4.45 126,663.60 12.91 1,415.65 1.77. 6 32,459 13.58 201,33432 20.52 -2,69630 3.38 71 1,423 0.60 730.00 0.07 27.04 0.03 72 6,85 2.87 11,535.40 1.18 130.15 0.16 73 .43,105 18.03 72,588.82 7.40 .819.00 1.03 74 18,918 7.91 31,85.91 3.25 359.44 0.45 7 70,296 29.40 116,712.13 11.90 1,335.63 1.67 82 3,056 1.28 18,336.00 1.87 1,521.89 1.91 83 211. 0.09 1,873.26 0.19 .105.08 013 84 1,370 0.57 13,563.00 1.38 543.89 0.68 85 13,490 5.64 172,375.22 17.56 19,965.20 25.01 86 1,475 0.62 18,847.55 1.92 2,183.00 2.73 87 33,145 13.86 . 347,657.91 35.43 49,054.60 61.45 8 52,747 .22.06 572,652.93 58.35 73,373.66 91.92 Lakes 34,568 14.46 0.00 0.00 0.00 0.00 Total 239,075 100.00 981,385.98 100.00 79,8249 100.00

(Percentage of region) (13.29) .(15.15) (34.86) SDurctAuthors'calculations from data basesderived fromlnd coverdassificationtand table4-1. 13 Southern Africa Roger Bevan

This chapter presents a detailed description of the It peaks at 0.06 in northern Namibia and souther mostimportantlandcoverclasses ithisregion.Help- Angola in March and July, but has a slightly greater ful figures in other chapters include figure 3-1 (cloud peak of 0.08 in September in southem Namibia. Pre- cover); figures 3-2, 3-3, and 3-4 (NDvisumnmary land cipitation is mostly less than 100 millimeters in the cover profiles); figure 3-5 (regional summary map of Namib Desert at the core of this class, but may exceed land cover classes); figures 7-1 and 7-2 (continental 250 millimeters in the wettest parts. maps of growing stock and sustainable yield); and the The coastal belt is largely frost-free, but there may "Regional Land Cover Class Map of Southern Africa" be only 5 or 6 frost-free months in southem Namibia at the end of this volume. and interior Cape Province. The slightly wetter areas. Helpful tables in other chapters include table 3-2 of this class largely coincide with White's "Bushy Kar- (land cover classes); table 4-1 (data and sources for roo-Namib Shrubland" and "semidesert" vegetation growing stock and sustainable yield); and table 6-6 (1983)and the drierparts of the "Dwarf Karroo Shrub- (southern Africa estimated woody biomass by sum- land," together with areas of the 'Kalahari/Karroo- mary class). NamiibTransition." These classes all represent transi- tions at the desert edge to areas of greater biomass. Class 0-Desert The Namib Desert occupies a coastal peneplain, an extensive area of bare rock often covered with mobile This class occupies approximately 6 percent of the sand. In southwestern Angola, the eastern part of the southern Africa region, including 20,446square kilo- Desert of Moc,amedes may rarely and locally support metersinAngola,29,457squarekilometersinBotswa- scattered low bushes and dwarf trees in depressions na, 221,478 square kilometers in Namibia, and 79,148 that receive water. In Namibia, true desert areas sup- square kilometers in South Africa. It comprises most port very little woody biomass However, on the des- of the NamnibDesert and its immediate environs, a ert fringes in the Namaqualand foothills, in the lower large triangular area stretching along the Atlantic Orange River Valley on the Namibian-South African coast from near Namibe in southern Angola to south border, and on higher ground to the east, this class of Alexander Bay in South Africa. It stretches inland may contain shrubland with widely scattered small about 100 kdlometers in southern Angola, but widens bushy trees and larger shrubs. Succulents are abun- southward to about 500 kilometers in Cape Province. dant, especially in the south. It is broken only by the slightly better vegetated Welwitschia bainesii is widespread from central Namaland Mountains in southern Namnbia. Outliers Namib northward, especially in the transition zone occur in the Great Karroo in Cape Province of South between the inner and outer Naminb.It is particularly Africa, the Etosha Salt Pans in north Namibia, the abundant in the shade of riparian bushland domi- Makgadikgadi Pan in northeastern Botswana, and in nated by Colophospermummopane and Terminailapn- degraded parts of the Kalahari Desert of south-central nioides. On the stony flats between watercourses, and southwestern Botswana. Welwitschiabainesii is the only woody plant, associated The phenology of this class shows a consistently low with grasses. On the margins of larger rivers, taller NDvi,mostly between 0.02 and 0.06for the entire year. shrubs and small trees such asAcaciaalbida, A erioloba,

136 -.Sailhcrn Africa 137

Eucleapsaeudebenus, Ficts sycomorus, Ritus lancea,and Although this latter area was previously classified Salvadorapersica occur locally, as "Woodland-Bushland" (irc Foundation 1987;Mil- In the outliers of this class in Cape Province, a lington and others 1989), it can have a more-or-less "Dwarf Karroo" vegetation dominates, including continuous grass sward and has a sufficiently similar dwarf shrubs, mostly Compositae, and larger shrubs, -Novi phenology to be classed with the veld grasslands such as Rlziguz0Um2trichotomum. Bushes and trees are of South Africa. In semiarid areas, classes may vary almost entirely absent and succulents are less promi- from year to year because of fluctuations in rainfall. nentthangrasses. Soilsoftenareslightlysaline,so that Although somnewhat ecologically dissimilar, the halophytes such as Salsolatuberculata are widespread. various regions of this class all have moderately high In the very arid Karroo, large, brackish flats or vloere productivity in the wet season, with NDVI values exist, sometimes covered by Salsolaaphylla and other greater than 0.35, reaching peaks of 0.43 in December halophytes, but often these areas are bare. and January. The values are sustained at greater than The Etosha Salt Pans of Namibia and the Makga- 0.35 from February to April, but decline to approxi- dikgadi Pan contain no woody vegetation. Outliers of mately 0.2 from June to September. A quick transition this class in the Kalahari may contain limited woody from greatersummer NOVIvalues to the smaller values biomass stocks. Southwestem Botswana's rolling of the winter months largely reflects seasonality in sand dune areas contain a few widely scattered trees precipitation and evapotranspiration. such as BosciaalbitruncaandAcaciamelltferm ss.detinens, The highveld grasslandsof South Africa are a typical occurring mainly on dune crests, with shrubs such as continental interiorhigh plateau ranging from 1,000to Rhigozu7n trichotomum confined to the interdune 1,800meters altitude. The grassland vegetation usu- troughs. Farther northeast, the rolling sandy country ally is considered the result of hot, wet summers and with wide plains, depressions, andpans includes trees cold, dry winters, which restrict tree growth (Taylor such as Acacia erioloba,A. nellihera(detinens), Boscia 1972). The growth of woody vegetation also is re- albitrunca,Dichrostadrys cinerea, and Terminaliasericea. stricted by other factors, such as the more frequent Low shrubs indudeAcaciahebedada, Bauhiniamacrantha, incidence of frost, which can be expected at least 80 Bosciaalbitrunca, Dichrostadlys cinea, Grewiaspp., and days a year for most of this class and up to 120 days in Ziziphus mucronata. the highest areas. Rainfall increases from approxi- This class is clearly of almost no value as woody mately 600 millimeters in the west to more than 800 biomass. The very limited standing stock would not millimeters in the east. The topography is a plateau, be replaced for many years if it were removed as a flat to gently rolling. It has predominantly black result of severe environmental constraints on biologi- montmorillonitic soils in some of the more northem cal production parts. In more southerly areas, soils are mainly add to neutraL yellow anld grey, sandy and loamy, and over- Class 11-Veld Grassland lie sandstones (Scheepers 1975). Most authors-for example, Werger and Coetzee High Veld Grassland is typical of the interior plateau (1978)and Acocks (1975)-distinguish "true" grass- areas of western Lesotho, Orange Free State, parts of lands from "false" grasslands, the latter being largely southwestern Cape Province, andsouthernTransvaaL anthropogenically induced. The former include the It constitutes nearly 6 percent of southern Africa and so-called sour grasses, tall grasses with wide, coarse occurs largely in South Africa (214,364square kilome- leaves that have less nutitive value in winter than ters). It coincides largely with White and Moll's "High "sweet" grasses. They usually occur at slightly higher Veld Grassland" (1978) and Werger and Coetzee's attitudes and form uniform-looking sward of And a- "Moist Cool Temperate Grassland" (1978). * pogonspp., Coris , Ergrosis spp., and Panicum Small outliers occur in Bophuthatswana, just north coloratum.Themeda triandra dominates the less-acid of Pretoria, and in small tongues within the coastal "mixed" and "sweet" grasses, which have short, nar- mountain ranges north of Port Elizabeth. Other small row leaves and often intermingle with forbs. outliers occur in the extreme southwest and northeast The "false" grasslands occur in potentially more of Angola (22,922 square kilometers) and in south- woody areas that have suffered excessive burning, central Mozambique (6,271 square kilometers). The overgrazing, or cultivation (Werger and Coetzee largest outlier of this class occurs in western and north- 1978). Overgrazing often results in replacement of western Botswana (53,380 square kilometers) and some of these species by tough and unpalatable northeastern Namibia (15,282 square kilometers). It Aristidaspp. and Cidorisvirgata. covers large areas of central Chanzi, Ngamiland, and Riparian woodland commonly exists along water- North East districts in Botswana and coincides with courses, although the trees usually are stunted as a the "Kaukau Veld" (White 1983) on the Namibian- result of climatic severity and exploitation. Partially Botswanaborder. wooded are the Mohokare and Sengu valleys in 138 EstimatingWoody Biomnass in Suib-Salnamn Africa

Lesotho, the Orange, Vaal, Madder, and srnaller trib- bushes include Acaciaciolobl, A,fleckii, A. hebeclada,A. utary valleys in South Africa, plus small valleys in the leuderitzii, A. me!lVera,A. tortilis, Bosciaalbitrunca, coastal ranges of Cape Province. The deep, sandy Dichrostachyscincrca, and Terininalia sericca,In the levees fringing theOrangeRiversupport riparien for- north, broad-leaved trees are more common, includ- est 6 to 10 meters tall, composed principally of Acacia ing Combrehtn collinum, Comniphioraafricana, C. on- karroo,Celtis africana,and Diaspyroslycioides. Else- golensis,Oclina ptilcira, and ZfziplIusmucronata, but where, these trees have a bushlike form and may with Acaciaspp. still dominant. In both areas, the trees include Rhus lauceaand Zizipi/us nmucrnata,as well as are always less than 7 meters tall (usually much A. karroo,C. afRicana, and D. lycioides. smaller) and are quite widely spaced, with dominant In dry, low-lying, undisturbed or protected areas, grassy sward beneath them. low bushland and scrubland less than 5 meters high An outlier of this class occurs in northwestem An- occurs. This is dominated by A. knrroo,Buddleja saligna, gola and extends into Zaire. It is described by Belgian Celtis africana,Cussonia spp., Diospyrosspp., Eluretfa writers as "steppes" and probably is the result of rigida, Eucleacrispa, Grewiaoccidentalis, Olea africana, degradation of woodland (see Chapter 11, Central Osyris spp., Rlus spp., and Ziziphus mucronata.South- Africa, Class 11). The other outlier in south-central ward from Lesotho, Aloeferox occurs on north-facing Mozambique takes the form of an "Open Shrubby slopes. Much of the southwestern Cape Province is Savanna Grassland." This was mapped by i-rc Foun- classified as "High Veld/Carroo Transition" by White dation (1987)and Millington and others (1989)as Dry (1983), with overgrazing having converted much of MiomnboWoodland but is, in fact, a degraded wood- this area to a secondary dwarf shrubland with graSsses land area, consistingof scattered low trees and bushes, such as Aristidacongesta, Cynodon kirsutus, Eragrostis includingUapaca spp., Monotesspp., and Proteaspp.in spp., and Themedatriandra. a well-developed grass sward about 0.5 to 1.5 meters Other areas of greater woody biomass occur in the. high. higher parts of eastem Orange FreeState and adjacent The fuelwood resource in this land cover class is areas of Lesotho. These are probably transitional to small, both in growing stock and sustainable yield. Transitional Wooded Grassland (Class 24) and Open More important, it is very patchy in distribution. In Woodland (Class 61). Northwest of Kimberley, this Lesotho and South Africa, fuelwood supply is further class occurs over coarse, stony soils where trees have restricted by the land tenure pattern. Consequently. been cleared for mining and where grazing has re- the potential fuelwood supply is poor in these areas, placed "sweeter" Themeda-dominantvegetation by the which include a number of important settlements such more "sour" Aristdaominant communities. as Teyateyaneng, Maseru, Mafeteng and Qu thing in Over much of South Africa, this class coincides with Lesotho; Virginia, Bethlehem, and Bloemfontein in the good ranching country, and in more temperate areas Orange Free State; L.dock and Middelburg in south- is used extensively for maize and wheat cultivation. western Cape Province; quite densely settled parts of The southern part of the so-called Maize Triangle Bophuthatswana, both north of Pretoria and west of coincides with the northern part of this land cover Lesotho; the north of Transkei near Matatiele; and the class in South Africa. Maize cultivation is extensive, north of both Ciskei and Transkei near Queenstown. with fairly small yields of 0.9 to 3.2 tonnes per hectare The pressure on limited woody biomass stock is (Christopher 1982). Wheat is grown in southeastern particularly marked near black townships and in the Orange Free State as a winter crop. Farther south, in densely settled rural areas of the homelands. Here, the "High Veld/Karroo Transition" of the southwest- pastoralism and subsistence agriculture are more em Cape Province, the land is largely devoted to common than the commercial agriculture which dom- pastoralism and subsistence agriculture. inates much of the heart of this land cover class. In northwestem Botswana and northeastern Nami- bia, this class is represented largely by the "Kalahari Class 14-Montane Grassland and Heathland Thornveld/Zambezian Broad-Leaved Transition" (White 1983) and is included as 'Plains Bushveld" Montane Grassland and Heathland covers only 15,440 class by Werger and Coetzee (1978). It is an area of. square kilometers of southern Africa, which is less coarse-textured soils on tropical plains with 500 to 700 than 1 percent of the land area. Nevertheless, this class millimeters rainfall a year- This wooded grassland is is locally significant in the Drakensberg Mountains the characteristic vegetation of the thick mantle of the and in Lesotho. True subalpine and alpine grassland KcalahariSands (White 1983). and heathland occur mainly in three areas in Lesotho In Botswana, the almost continuous grass sward is (Mokhotlong, Qacha's Nek, and Thaba-Tseka dis- lessthai1rneterbighandconsistsof Anthephoraoargentea, tricts) which total 7,535 square kilometers and four A. pubescens,Eragrosfis spp., Panicumkilaharense, and small areas in adjacent South Africa and Transkei, Schmidtia spp. In the south, the principal trees and mostly in the Drakensberg range, between Kopshorn -.SOIer11AfrIca 139 and Scobell'sKop near BarclayEast, which total 6,587 Mozambican.border into southern Mozambique squareldlometers.Smalloutliersalsooccurtothewest. (16,388square kilometersare in Mozambique)and aboveRouxviile and Sterkstromin easternCape Prov- into northern OrangeFree State. ince,also at high altitude.All area In this classIs above The other area stretches north-northwestto south- 1,500.meters, and the majority of it is above 2,00D southeast adjacentto the drier classesof land cover meters. that borderthe Namib Desert,from southwestern An- The phenologyof this classexhibits a fairlymarked gols(15,967square kilometers) across centralNamibia seasonalpattern, with a moderatelyhigh NDVIof 0.35 (161,458square kilometers),into northem Cape Proy- in the warmer period of Decemberto April, rapidly ince. Outliersoccur in South Africain the Langeberg giving way to values of about 0.19in the cold period Mountains, Asbestos Mountains, Mount Gakarosa, fromJune to October. and Kaap Plateau of northem Cape Province,near The subalpinebelt in Lesothoexists between 1,830 -Kimberley on the border between Orange Free State meters and 2,895meters. Soils are verythin and stony and Cape Province,and in a few small areas in the and the climateis severe. Rainfallis variable (500 to coastal ranges of southern Cape Province, on .the 1,200millimeters) and much of it fals as snow..Tem- north-facingslopes of the Langebergand Kougaberge peratures colder than 0°C are commonin winter, but ranges. Altogether this class covers 171,365square in Januarymean temperaturesof about 15°Care com- kilometersin SouthAfrica. Small areas totaling25,294 mon.The frost-freeperiod is about 185days. square kilometersalso occur in the exTremewest of Subalpinevegetation is dominatedby fire-controlled Zambia. Th1emeda-Festucagrassland, the speciesof which differ Thisclass coincides largely with areas receiving200 with aspect and altitude. Chrysocomadominates the to500millimeters rainfall a year, although a minority grassland over about 13 percent of this zone, and this of areas receive substantially more..The phenology is believedindicative of overgrazing.The scant woody variesslightly be tween eastern and westernrepresen- vegetationin the subalpinebelt indicatesa very small tatives,as follows. fuelwoodpotentiaL. In eastemBotswana, the seasonalityis less marked The alpinevegetation occursin more severecondi- becauseof a lowproductivity in wet season.The great- dionsthan the subalpine grasslandsand is dominated est NMVIvalues occur in April, May, and November, by homogeneouslow, woody heathlands.The domi- when levelsof 0.21to 0.25are recorded.For the rest of nant species,Erica spp. and Helichrysumspp., are in- the year, a low levelof between0.12 and 0.18is main- terspersed with grassland. All are evergreenwoody tained (figure13-1). plants adapted to the cold, dry climateand all show a hI northwesternNarnibia, seasonality is somewhat reduction in height with increasingaltitude. Various greater,-butthe overallannual levels are siml. Peak vegetationtypes correspondto differentenviromnen- Nrvi values of 0.33and 0.30 are experiencedin March tal situations,such as bogs,pools, stream banks, wet and April,declining to 0.12in Decemberand January and dry meadows,and cliffs,but almostall are domi- (figure13-1). nated by grasses,mosses, and herbs. In eastemBotswana, this land coverclass is floristi- Only the heath communitieshave a large propor- callysimilar to the AcaciaWoodland Mosaic (Class 51) tiDonof woody species,but evenin the best developed and the OpenWoodland (Class61) areasto the north, of thesecommunities, which are restrictedto the sum- dominated by Colophosperinummopane, with Acacia mits of the Drakensbergs,the woody species rarely attain more than 1 meterin height.Isolated patches of scrub, often only up to 2 meters in height, and domi- Figure13-1. NDVIProfiles, Transitional Wooded nated by Buddlja corrugata,Leucosidea sericea, and Grassland (Class24) Passerinamontana, exist in undisturbed areas on the lower mountain slopes (Millingtonand others 1989). 0.6. However,no fuelwood resourceexists over much of - 24Eastem Botswania this part of the class. 0.5 .- 24 NorthwestemNamibia

Class 24-Transitional Wooded Grassland 0. cz0.3-: / \: Two large areas of thisclass, together with a number 2 of smallerareas, cover more than 650,000square kilo-. 0.22 meters in southerm Africa. One area is in eastern Botswana(240,607 square kilometers),southwestern Zimbabwe (25,610square kilometers),and northernm; , TransvaaLOutliers extend along the SouthAfrican- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 140 EstirmatingWoody Biormss in Sub-S liaraliAfrica spp., Combrefinnspp., Tertninaliaprunioides, and Ziziphus inated by Grewiaflava,Ormocarpum#1 triclocarpum, Rits mucronataand including shrubby Colopbospmerummop- pyroides,and Ziziphus mucronata. ane,Grewiaflava, and Teninnaliasericea. A strong ecolog- In other areas, vegetation is restricted to thorny and ical gradient exists to the west, and once the sandier spinyshrubsscattered amonggrasslands. Woody shrubs soils developed on the Kalahari Sands are encoun-- andstuntedtreesreachabout5meters.Typicalwoody tered, it grades rapidly into bushland and shrubby constituents are Bfca spp, Cormi*ora spp., Dichro- bushland. Floristically and structurally, it is therefore stad:ysdinema, Grewiaafava, Lycium spp., Rhigozuinbrevi- quite diverse, but nearly always has a well-developed spin asum, Ternminalia prunioides, and Ziziphus. grassy sward. -mucronata. The only common emergent is the low, Eastward, the class continues into southwestem shrubby Colophospennummopane, which here rarely Zimbabwe and northem Transvaal, mostly on the exceeds 5 meters in height and often reaches only 2 flanks of the Limpopo Valley,being most extensive in meters. It occurs as scattered individuals in a shrubby Matabeleland South. It occurs along the hot, dry ground cover interspersed with grasses. Limpopo Valley and along the northern tributary val- On escarpments overlooking the river valleys is a leys of the Mwenezi, Shashe, Tuli, and Umzingwani very open savanna of small trees and bushes. The rivers (as well as in the middle of the Sabi Valley in the structure varies from dense woody stands reaching 4 east) in Zimbabwe, and the southem tributary vaUeys to 8 meters in height, through a variety of shrub types, of the Mogol, Palala, Mogalakwena, and Sand valleys to the most arid form, in which trees rarely exceed 3 in the Transvaal. The class also includes a large part of meters and vegetation is very open withgrass and fem the lower Limpopo Valley in northern Venda. layers dominant. The species are related to those in the In these regions, it also contains a variety of similar lowlands,andthemainwoodyspeciesareAcaciaspp., vegetation types-"Arid and Dry Mountain Bush- Androstachys johnsonii, Boscia albitrunca, Colophos- velds," "Arid Spiny and Thom Plains Veld,' "Ter- permum mopane, Combretum apiculatum, Commiphora minrallaSandveld,' and low "Colophospermummopane glandulosa,Kirkia acumizata, Plerarpus rotundfolius, Bushland" (Werger and Coetzee 1978).All the vegetzr Terminaliaprunioides, and Ximeniaamericana. uon types are dominated by low trees and bushes, - stribution of the various species is in. :nly depen- some of which are emergent trees above a well-devel- dent on soil properties. On sandy parts of the High- oped ground layer of grasses and herbs. They are veld, Terminaliasericea-dominated savanna occurs, similar in phenology, biomass productivity, and with an open canopy and with slightly taller trees, growing stock usually 8 to 10 meters high, underlain by a well-devel- Especially in the dry valleys & southern Zimbabwe, oped grass layer with few shrubs. These areas may be a deficit in soil moisture exists during the long dry extensively grazed (Mllington and others 1989). season. This seasonal drought is accentuated by two In Mozambique, this class coincides largely with factors. First, soils have low infiltration capacities and White's "Halophytic Communities" (1983).Rainfall of high runoff rates; consequently, little rainfall during 400 to 600 millimeters a year with moderately saline the wet season infiltrates and replenishes the soil soilsproduces grassland withAcacia niloticass. kraussi- moisture reserve. Second, rooting depth is very -m- anawith extensive bare areas. However, much of this ited in many cases. Th-evegetation is adjusted to these area is agriculthral land or degraded land, character- inhospitable dry-season conditions. ized by low productivity and marked seasonality. Slight variation in soil properties is reflected in These areas aredominated by agriculture, which has slight variation in the vegetation communities- On the destroyed the vegtation to such an extent that occa- alluvial soils of the river valleys, low shrubby vegeta- sionally only very small patches of thicket and grass tion is domiinanLVariation in the vegetation conmmu- savanna are left between farns. These usually are nities reflects variation in both soil texture and fertil- areas either of scmbby vegetation less than 3 meters y, as well as disturbance. The latter can be quite high or of open, grass-dominated savanna with iso- extensive, as many of these soils are quite fertile and lated trees which attain 5 to 10 meters. suitable for grazing or cultivation. A few areas of In northern Transvaal, this class occupies a signifi- badly degraded savanna do occur in these valleys, and cant area along the Limpopo Valley, as described ear- the land grades into low, unproductive Wooded Shrub- lier, but it also extends south of the Soutpansberg land (Class 35). Mountains onto higher areas northwest ofPietersburg Vegetation in the Limpopo Valley is open grassy and southward along the Mozambican border in Kru- savanna with a smaller woody biomass component ger National Park. It largely consists of a dry savanna This is mainly restricted to scattered emergent trees type of vegetation-"South Zambezian Undifferenti- such as Acacia spp., Dichroslachyscinerea, and Sclero- ated Woodland and Scrub Woodland," according to caryacaffjra, which attain heights of about 10 meters, White (1983). It usually occurs on alkaline soils of and scattered shrubs varying from 1 to 3 meters, dom- hotter, drier areas of lowland valleys and rejuvenated Soauhermi Africa 141 upland regions. Calcretes are common. Rainfall varies Termilnaliasercea. become more frequent. This also is from 325 to 1,000millimeters and altitude from 150 to the case in the small outliers of this class in the west of 1,525 meters. Botswana and the extreme northwest of Cape Prov- Well-developed woodland more than 9 meters tall ince. Occurrences of this class in Namibia largely co- is localized; elsewhere, it is mostly scrub woodland. incide with the more densely populated areas, includ- Most of the larger woody plants are about 7 meters ing Windhoek, and with areas of privately owned high with occasional taller emergents. In its natural farmland, which is principally devoted to cattle ranch- state, the vegetationcan bequite dense, or even closed, ing (van der Merwe 1983). but never impenetrable. Some of this is now preserved Other outliers occur farther south in Cape Province. in the KrugerNationalPark,but elsewhere innorthem The area just east of Springbok coincides with the Transvaal the area is extensively grazed. A wide vari- "False Succulent Karroo" of Acocks (1953)and is very ety of species includes Acacia spp., Combreturnspp., similar to the areas in the north inNamibia, exceptthat Coimiphora miaollis,Dichzrostachzys cinerea, Diosptyros succulents are more abundant. The large areas north miespiljformis,Sclerocarya cafra, Ternuinaliapruinioides, T. west of Kimberley in the Langeberg and Asbestos sericea,and Ziziphls imucronata.Commonly referred to mountains, and northern Kaap Plateau, as well as as the 'Transvaal Bushveld' (Christopher 1982),the those southeast of Kianberley in Orange Free State, drier parts are suited only to exter'sive cattle grazing, correspond with the "Kalahari Thornveld and Shrub and cultivation depends on irrigation. Bushveld' of Acocks (1953)and White's "Bushy Kar- The other significant area of this class stretches roo Shrubland" (1983).A similar vegetation ecology north-northwest to south-southeast, from southwest- occurs in the coastal range outliers, described by em Angola to the north of Cape Province. The most Acocks (1953) as "Succulent Mountain Scrub" and northerly of these areas is on the lower slopes of the "Karroid Broken Veld.- coastal ranges inland from the Desert of Moqhmedes. All these areas have a distinctive shrub layer with a Examples occur along a distinct north-south-oriented scrubby succulent vegetation. Small trees and shrubs altitudinal zone along the coast between Namibe and include Aloe dichotoma,-Ceraria namaquensis, Euclea Tombua, and on the high ridges of the Serra da Chela. tomentosa,and Ficus ingens,with smaller shrubs often Here, as farther south, this class is largely adjacent to of Euphorbiaspp. Shrubs usually are less than 2 meters the Desert (Class 0) and Bushy Shrubland (Class 33). tall, but larger woody plants, either arborescent suc- The vegetation is mainly low, open, and shrubby, culents ornonsucculentbushy trees, are scattered over with some taller shrubs to 7 meters in height (for the landscape. These rarely exceed 5 meters in height, example, Acaciamellifera, A. reficiens,and Commiphora the most notable being Acaciaerioloba, A. melliferass. zngolensis), passing into Colophospermummopane- detinens,Aloe dichotoma, Boscia spp., Cerria spp., Cotj- domnmated communities with grasses on the higher ledonpanicaata, Ehretia dgida, Euphorbia spp., and Grem7a parts. Around the Angolan towns of N'Giva, An- flav. hanca, Evale, Namacunde, Nehone, and Moygua, this This vegetation is floristically similar to Wooded land cover class is a degraded form of Open Woodland Shrubland (Class35),butincludes areas of commercial (Class 61) to the north. This is a secondary vegetation agriculture, such as the irrigated zone along the Or- dominated by stunted tree thickets on grassland, ange River near Upington. caused by clearance near settlements and, in part, by Although the growing stock is greater than in many military activities and rural population movement adjacent semiarid areas, the annual productivity is Very extensive areas of this class occur in the high quite small, which limits fuelwood extraction from plateaus of Namibia, including large areas innorthem this land cover class. It is a tranrsitionalclass between Ovamboland, around Windhoek in central Namibia, woodland and grassland, but more the latter, and and in the higher parts of Namaland, including parts commnonlyis used for extensive grazing. Although of the Hanam Plateau. The communities often are some floristic overlap with other land cover classes dominated by Colophospermummopane, with Cenaria probably exists, this class is phenologicaly distinct in longepedunculata,Commiphora spp., and Sesamotham- the 1986 AvmHRRNVIdata. nus spp- occurring as trees to 15 meters height over a Many areas in this class already have been exten- grassy sward- Farther south through Namibia, the sively exploited, as in southern Angola, in the principal bushes and trees gradually become Acacia Limpopo Valley in Zimbabwe, and in the Cliangane spp., Combretumapiculatum, Dombeya rotundtfolia, Eu- Valley in Mozambique. In many more-open areas, ceia undulata, Ficus spp., Rhus marlofii, and Tarcho- growing stock not only is small but is scattered. In nanthus camphoratus. southemr Zimbabwe, some of these areas coincide In the more eastem parts on the fine red Kalahari withcommunalareas, where deforestationis common Sands, Acaciamelli#ra ss. detinens, Catophractesalexan- because of fire and land needed for grazing, cultiva- dri, Combretum apiculatum,Dichrostakys cinerea,and tion, construction timber,-and fuelwood. In other -142 EslimoaingWoody Biomanss in Sib-Soaran Africa areas, such as Kruger National Park, woody vegeta- Diospyrosaustro-africana, Euclea spp., Maytenus letero- tion is protected from exploitation. Overall, it is a land pitylla,Osynis spp., and Rhus spp. These occur as scat- cover class of limited fuelwood potential. Its woody tered individuals 2 to 3 meters high, or locally as small bioniass growing stock is estimated at 41 million thickets. tonnes for the whole of southern Africa, with a sus- This densely settled and intensively cultivated area tainable yield of 6.1 million tonnes. is not a significant source of woodfueL and access to the limited stock of woody biomass undoubtedly is Class 31-Veid Shrubland and Cultivation restricted by pattems of land ownership.

This class occurs only in South Africa. It covers 4,005 Class 32-Hill Shrubland square kilometers of westem Cape Province, partly in lower, flatter land around the Great Berg River, south- This land cover class is relatively limited, present only eastward from St. Helena Bay and partly inland from in South Africa, covering 24,978square kilometers. It Piketberg to Malmesbury, including some of the low is limited largely to the lower slopes of western Cape hills up to about 800 meters. It occurs mostly on the Province, occurring mainly at the foot of the north- Malmesbury Shales and part of the Quatemary and northwest-trending subparallel coastal ranges, in- Tertiary Sands nearer the coast. It coincides with the cluding the Cedarberg Ranges in the south, the Bok- "Coastal Renosterbosveld" of Acocks (1953),.now re- keveldberge and the Hardeveld in the center, and the ferred to as "Renosterveld' by Taylor (1978) and as slopes around Springbok, Nababeep, and Steinkop in "Coastal Macchia" by Moll and Bossi (1984). It also the north. overlaps in the north with the "strandveld" of Acocks The ranges are composed of the Table Mountain (1953). Sandstone or the Wttteberg Quartzites of the Cape This class has a phenology distinctive from the System, while the Cape Granites frequently form the "Bushy Karroo-Namib Shrubland" that mostly sur- foothills and lower slopes, leading down onto the rounds it, having a much more marked seasonal pat- Bokkeveld Shales and sandstone of the Cape System tem. Precipitation occurs almost entirely in winter, on the lower ground. The soils havelittle water-retain- totaling 570 millimeters a year. A low summer NDv1of ing capability, are acidic, and generally are infertile. about 0.12 occurs from November to May. This in- Deeper, brown or reddish sandy loamnsthat are more creases quite rapidly to approximately 0.58 in July, ferile occur c:er granites and shales. August, and September in response to the winter Precipitation varies considerably with relief from rams. 150 to 250 mimeters in the north to more than 500 This class coincides with an area of shales that millimeters in the south, with a distinct winter maxi- weather to form fine-grained soils, denser and more mum. This class includes "Mountain fynbos" areas in fertile than the sands of the mountains or the coast on the south. The term fynbos has been used to describe which Hill Shrubland and Bushy Shrubland (Classes the Mediterranean-type evergreen sclerophyllous 32 and 33) occur. This is the so-called swartveld, a shrubland, but it equally may be classed as a form of gently undulating landscape which has been exten- heathland (Moll and Jarman 1984).Acocks (1975) de- sively plowed for wheat cultivation, so that only traces scribed these areas as "Macdhi; others, such as Moll of natural vegetation remain. This has been one of the and Jarman (1984),refer to some parts as 'Mountain most important wheat-growing areas of South Africa Renosterveld." Farther north, the class includes the since early white settlement and, although yields are more southerly parts of the "Karroo-Nimnb Domain" small, it remains a prime producer of South Africa's of Werger (1978),also referred to by White (1983)as wheat Wheat is grown in rotation with oats and other "Bushy and Succulent Karroo Shrubland!" cereals, with some sheep farming, using stubble or The NDVI phenology is similar to Bushy Shrubland fallow land. These virtuaRy continuous wheatlands (Oass 33), reflecting a Mediterranean-type seasonal (Christopher 1982) contrast markedly with the sur- pattem,butwithaslightlyhigherNrvrlevel,especially rounding shrubland. in winter as a result of the greater precipitation. Be- Natural communities that do remain are dominated tween December and June, NDvilevels are 0.12 to 0.15, by the shrub Elytropappusrhinocerotis (renosterbos), increasing to 0.22to 0.3 from July to October, pealdng usually densely branched and about 05 to 1.5 meters at about 03 in September. high. Grasses often form a significant component, and In the southern true Mediterranean area of thisclass, scattered patches of tail scrub 3 to 4 meters high may the "Mountain fynbos" is very complex floristically. It occur, often introduced plants such as the Australian changes from tall, proteoid shrubs 1.5 to 2.5 meters Acaciacyclops, A. saligna,and Leptospermumkeviga tum. high on the lower slopes to shorter, ericoid forms on Semisucculent and broad sderophyllous plants also the upper slopes, with restioids often dominating the occur, as do species of tropical affinity, principally exposed ridges. Proteanereifolia is the most common SouthernAfrica 143 shrub on the lower slopes. Only rarely are small trees (1983),and some classified as "Coastal Renosterveld" observed, although Hieea argenteaand Mayenus oklides and "strandveldc by Acocks (1975).Much of this latter occur on rocky hillsides. Where surface rock is exten- area has been disturbed and degraded to a "Coastal sive, Maytenus acurninata,Olea africana,Olinia ventosa, Macchia,' according to Moll and Bossi (1984). and Podocarpuselongatus may form a closed scrub Precipitation varies between 150 and 250 milime- forest 7 to 8 meters in height. Ola capensisand Wid- ters in the north but exceeds 300 millimeters in the dringtonia cupressoidesalso can occur as scrub forest, south of this area; most falls in the winter months. usually less than 7 meters tall. Mean daily temperatures vary from about 13°C in Above the proteoid zone, the shrubs are smaller, July to about 22°C in January. The topography trends usually only 1.5 meters high, and are dominated by parallel to the Atlantic coast (northwest to southeast) ELic spp. and Phylica spp. Trees.are absent except in and southern coast (west to east) with the two series the Cedarberg ranges, where Widdringtonia cedar- of folds meeting near Ceres. This class dominates the bergensispersists on rocky scarps and screes. Upper lowerlandaroundthecoastandbetweentheseranges. parts of these mountains exhibit a low restioid vege- In the valleys, this class overlies Bokkeveld Shales tation, usually less than 0.5 meter high, such as that in and sandstones of the Cape System and the the northern Cedarberg Mountains. There, Restio Malmesbury Shales of the Archaean Complex. Along curziramis can form dense, low, rounded, cushionlike the coast, it overlies sands, conglomerates, and lime- tufts 20 centimeters high, with Cannamoisnitida grow- stones of Tertiary and Recent age. Soils from the ing in dense tufts 1 meter high. Bokkeveld series are fairly fertile, but coastal soils are Farther north in western Cape Province, this mon- often shallow and clayey. tanevegetationgrades into the southern end of Wergers The other significant occurrence of this class is at the 'Western Cape Domain" (1978) of the Karroo-Namib northern edge of the lDesert of Mofimedes in Angola. region. This area was classified as "Western Mountain It extends along much of the Angolan coastal plain Karroo" by Acocks (1953).At its northermlimnit,succu- and along the foot of the escarpment inland from the lent dwarf shrubs are fairly common, but farther desert areas in Benguela and Namibe provinces. This south, as precipitation increases, succulents are less area coincides with the northern end of the "Nama- common and the dwarf shrubs grow only 1 meter land (or Namaqualand) Domain" of Werger (1978) high. These includeAsparagus capensis,Cotyledon wallt- and the northern extreme of the "Bushy Karroo Shrub- chi, Euphorbiamauritanica, Galeni aft cana,Pentzia spp., land" of White (1983).Patches also occur in northern Pteronia glauca, Ptemothrix spinescens, Ruschia ferox, Namibia, including an area on the fringe of the Etosha Zygophyllum gilfillani, and others. Higher up the Pan. Precipitation levels are less in this area, often less mountain ridges, between Calvinia and the southern than 100 millimeters, and mean daily temperatures Cape Mountains, this karroid vegetation merges into reach 15°C in July but only 20°C in January. "Mountain Renosterveld," with dwarf shrubs such as The phenology of this class in western Cape Prov- Elytropappusrhinocerotis, Eriocephalus afiitanus, Pentzia ince demonstrates the effect of the winter rainfall max- incana, ReLhaniaspp., and Ruschiamultifora. imum, with NDvi values of about 0.19 from July to Woody vegetation decreases northward through- October (ate winter to sprng), decliiing to slightly out this class, but nowhere is it of great significance. It lower values of approximately 0.12 from December to is dominated again by small growing stock and poor May. Although of similar level, the phenology curve sustainable yield. for the Angolarn extent of this class shows a near reversal of this pattern, with values of 0.04 between Class 33-Bushy Shrubland July and January, and slightly greater values above 0.12between February and May. The generally lower This class covers an extensive lowland area along the NDvivalues in Angola probably reflect less precipita- westem coast of Cape Province from Cape Town to tion. The different seasonal pattern reflects the slight the Namibian border, stretching along the southern summer maximum of rainfall in this northern part of coast as far as Cape Barracouta, and reaching into theclass. interior Cape Province as far as. the Roggeveld. It Floristically, the southem area of the class is one of covers 117,405 square kilometers, with 70,032 square extreme diversity (Taylor 1972), but with few woody kilDmetersinSouthAfrica,33,725square kilometersin plants or trees. Typically, theJynbos occurs in the form Angola, ard 7,483 square kilometersinNamibia- of sderophyilous shrubland of 1 to 3 meters height, It coincides largely with the 'Western Cape Do- with some scattered taller bushes and, rarely, widely main" of the "Karroo-Namib Realm" of Werger (1978), spaced trees. In many parts of the Cape lowlands, this although it also includes some areas dassified as class has been replaced by secondary shrubland dom- "Cape Shrubland" (part of the fynbos) by Werger inated by Elytropappus rhinocerotis (renosterbos). (1978),some classified as "Capensis Realm" by White Streams may be fringed with riparian thicket and Africa 144 Estirnali,igWoody Biomnass in Sub-Slalart dunes where areas of bare saline flats and grassy sand Proteaspp. bushes and other taller Strychnos scrub forest. The the only woody species is the shrubby in bushierfinbos may thicken to form African plants that occur spinosa. However, it is similar to the South 6 meters high, but large areas are de- and the thickets 4 to occurrences in form and growing stock, overgrazing, and cultivation. in height graded by fire, woody component rarely exceeds 2 meters fora is characterized physiognomicaUy The varied except near the escarpment. restioid, ericoid, and proteoid. to grazing, by three elements: Land use in this class is mostly limited is tufted, 20 centimeters to 2 meters olive- Restiold usually except around Cape Town where cultivation, leafless tubular or nonwoody stems. occur. This high, with nearly growing, and commercial stock-rearing is characterized by small, narrow, rolled fuelwood value, Ericoid to 6 land cover class is of very restricted Proteoid is represented by taller bushes stock, a small wood-to- leaves. with dominated by a small growing with leaves moderate in size, but still yield. Little meters, to grass ratio, and a fairly small sustainable small woody elements. Species common exists except lo- relatively the potential for fuelwood exploitation western and southern coast areas include stock is estimated both race- cally. The woody biomass growing Anthospermum aetitiopicum,Eriocephalus a sustainable yield of 5.7 ericoids A con- at 116 million tones, with E. umnbeflulahus,and Metalasiamuricata. ntosus, Proteoids million tomnes. spicuous restioid is Thamnoclwrtuserectus. by Leucadendronconiferum, L muinni, are represented Class 34-Kalahari Shrubland Proteaobtusifolia, and P. susannae. true trees are virtualy absent The Africa, an area In typicalfyibos, This class covers 4 percent of southem well-defined boles are Leucadendron kilometers. It only species with of nearly a quarter of a million square and W.schwar- of south- argenteum,Widdringfoniacedarbergensis, mostly coincides with the E41ahari Desert and W. cupressoides,whichoften occur south- zii. OIeacapensis western Botswana (52,643 square kilometers), here exhibit a bushy habit and are and as tees elsewhere, eastem Namibia (63,603 square kilometers), talL Dense thickets up to 6 meters kilometers), less than 7 meters northem Cape Province (129,367square on stream banks and are dominated occur 'm sometimes occur induding parts of the and Karroo. Outliers lanuginosaor Leucadendronsalicafolium. The Desert, the by Berzdia the higher areas to the east of the Naniib its seeds from fire, and many other and in small latter protects southern Great Karroo of Cape Province, have many protective characteristics with fjnbas plants areas in central Botswana. It mostly coincides aginstfire. Aaz Bushland and covered by White's 'Kalahari Deciduous Because of intensive land use in areas and with the '¶ualahari/ by alien Wooded Grasland" (1983) tiis class, many areas have been invaded A. cyclops, A. Karroo-NamibTrarsiion:' species, especially Accia cyanophylla, in these areas ranges f rom 80 to 250 and Pinus pinaster. The Precipitation This class melanoxylon, Hakeaacicularis, millimeters, with a summer maximum. gradual water courses are fringed lower and more only a slight seasonality, with a fairly uniform. 5 to 7 meters tall, of Brabeium. shows to 0.17 with dense thickets, tiroughout the year that varies from 012 oppositifolia,and Metrosiderosan- NDVI slellatifolium,Freylinia foreverymonthexceptFebruaTy,whenitpeaksatO.21 some Cunoniacapensis, Harfogia Wpen- than for the gustifolia,with (figure 13-2). This is somewhat lower Maytenus oleoides. ocors on its sis, flex miis, and Wooded Shrubland (Class 35), which In the northem part of this class, in southwestern "Nama- Angola, the vegetation forms part of Werger's (1978),a low, open, shrubby vegetation (Classes 34 land Domain" Figure 13-2. NDVI Profiles, Shrmblands withoccasionalsucculents,andwithisometalershrubmeUifera, and 35) communrtitiesinduding, for example, Acaca Commiphoraangolensis. On higher A reficiens, and r. shrub vegetation grades into Col- areas inland, this - 34 Botswana. mopane communities, with some grasses ophospermum soils. 0.5- 3 sites that are less rocky and that have deeper on may con- OA Along streams and valleys, the communimtes species of Commiphora spp. and Euphorbii tain several a 3- as Catophractesalxndr, Phaop!uMmsP no spp. as well z vwrgatum. sum, and Rhigozum 02- Muchof thecoastalvegetationin thispartofAngola as "Dry classified by Millington and others (1989) was A thin - Coastal Savanna" and 'Arid Coastal Thicket." in this dass, O , band of deserdike vegetation is included Jul Aug Sep Oct No c induding Jan FebMar AprMay Jun stretching along the coast north of Lobito, SoutihrnAfrica 145 slightly wetter margins (figure 13-2).On its drier mar- Karroo areas of Cape Province. Here it occupies large gins, this class often is adjacent to the Namib Desert. areas to the north of the coastal ranges, covering In southwestern Botswana and southeastern Nami- 123,781square kilometers. In Namibia, it occurs as a bia, the vegetation is very sparse on the rolling sand series of broken patches in the higher ranges, trending dunes with few, widely scattered trees, always less north-northwest to south-southeast, on the inland side than 7 meters tall and normally much shorter. They of the coastal desert areas, covering 50,061 square mostly occur on dune crests and include Bosciaal- kilometers. bitunca and Acaciamellifera ss. detinens. Shrubs such as A few smail areas occur in southwestern Angola, Rhigzunmtrichotomum are confined to the troughs be- north and east of the Desert of M5imedes covering tween the dunes. Shrubs restricted to this area include 2,002square kilometers.In Botswana,it occurs largely in Acaciahaematoxylon and Monedhmaspp. Farther to the wetter areas to the east and northeast of the Kalahari northeast, in Botswana, the small outliers of this class Desert,covering60,547square kilometers Small outliers may contain a slightly greater tree component with occur on the border with Zimbabwe near Tuli, in north- Acacia spp., Burkeaafricana, Combretum spp., Commi- emTransvaal,andindrierpartsofinteriorMozambique. phoraspp., Peltopharumacum, and Terminaliaserice, This class has fairly uniform NDVIvalues throughout but again they are mostly confined to sand ridges and the year, between 0.15 and 0.18 every month except have limited annual productivity. Similar parallel JanuaryandFebruary,whenitincreasesto .22 (figure ridges of sand dunes occurinnorthernCape Province, 13-2).This profile reflects the slightly greaterpotential where the commonest scattered trees are Acaciaemoloba, for woody biomass production in this class than in the A. reficiens, Albizia anthelmintica, Bosda albitnrunc, and drier Kalahari Shrubland (Class 34). Precipitation is Tenrinalia sericea.Similar species occur in the Great mostly 100 to 250 millimetersa year, with a distinct Karroo outlier of this class, but the woody component summermaximum, butmay exceed 400 millimeters in is limited to bushes and small trees; most are less than the northeastern outliers. 3 or 4 meters highl. Wooded Shrubland mostly coincides with White's In the outliers bordering the hills above the Namnib "Bushy Karroo Shrubland" (1983)in SouthAfrica and Desert, the vegetation is a very dry form of White's Namibia. This is a shrubland dotted with smallbushy "Bushy KarrooShrubland" (1983).Arborescentsuccu- trees and large shrubs. It occurs in the KCarroo,where lents or nonsucculent bushy trees, usually less than 5 soils are mostly derived from Dwyka tillite and doler- meters talL are scattered above an open shrub layer 2- ite, and often are clayey and have a tendency to accu- metershigh Succulent species include Aloe dichotoma, mulate salts. The class also occurs on rocky, well- Cerariaspp., Cotyledonpaniculata, Euphorbia spp., and drained mountain slopes in Namibia. Pachypodiumspp., with some water-stonrng species, Succulents are abundant, often dominating non- such as Cyphostemmacurrlii. A wide variety of non- succulent smaller shrubs. Shrubs are usually less than succulent bushes, bushy trees, and tall shrubs also is 2 meters tall, but larger, woody plants, either arbores- present, including Acacia erioloba,A. mellifera ss. centsucculents ornonsucculentbushy trees, are tinly detinens,Boscia spp., Ehretiarigida, and Grewiaflava. scattered throughout the landscape. They rarely ex- Land use in this class is mostly very extensive graz- ceed 5 meters in height and often are confined to ing. It indudes the Gemsbok National Park of south- rockier areas where water supply is enhanced by run- western Botswana and northern Cape Province, as off or seepage from surrounding slopes. well as other game reserves. Of the arborescentsucculents, Aloedichotoam(which Althoughthe fuelwoodresource issomewhatbetter grows to 5 meters) is the most abundant, with Ceraria than in the desert that this class fringes, this class has spp., Cotyledonpaniculta, and Pachypodiumspp., all of a small sustainable yield. Where extraction takes which attain 3 to 5 meters in height Toward the north, place, it greatly exceeds the annual rate of wood pro- the succulents Euphorphiacurrorii and E. eduardoi ductivity. Growing stock is esfimated at 145 million occur; also present may be species with water-storing tonnes, with half of this in South Africa. The sustain- stems, such as Cyphostemmnacurrorii, Moringa oualifolia, able yield is estimated at 12 million tonnes. and Sesamothamnusspp. (White 1983).Succulent arbo- rescents are less common in the south on the Karroo. Class 35-Wooded Shrubland Awidevanetyofnonsucculentbushes,bushytrees, and tall shrubs are likely to occur with varying den- Wooded Shrubland covers 4 percent of southen Af- sity, including Aacia erioloba,A melZiferass. detinens, rica, occurring on 244,644 square kilometers. It is Bosiaspp., Ehretiargida, and Grewiaflava.In the north, largely adjacent to, and very similar to, Bushy Shrub- Acaciamontis-usts, A. robynia, Adenolobuspeckueliti, land (Class 33), but usually occurs on the wetter mar- Colophospermummopane, Commiphoraspp., Euphorbia gins, often at higher altitude, although not always Its guerichiana,and Rhigozumuiz'rgatumoccur in scattered type area is in the central Upper Karroo and Great cLusters,2.5 to 4 meters talL 146 EstisnalingWoody Bionwss in Sib-SaolranAfrica

In Botswana, this class coincides with White's Cape Provincein South Africa,between Cape Town "Kalahari Deciduous AcaciaBushland and Wooded and Port Elizabeth, 17,021-square kilometers in all. Grassland" (1983)and was classified as "Southern Theseareas were classifiedby Acocks(1953) and Moll KalahariBush Savanna" by Weareand Yalala(1971). and Bossi(1984) as "Macchia"or "FalseMacchia," but This vegetation largely occurs on the rolling sandy they also contain large cultivatedareas. country of the slightly wetter parts of the Kalahari Theclass occurs on south-facingparts of the coastal Desert,an area of wide plains, depressions,and pans. ranges, which are composed mostly of Table Moun- The main tree speciesare Acaciaerioloba, A. nelliferass. tain sandstones and shales, and on the coastal low- detinens, Boscia albitrtnca, Diclirostachyscinerea, and lands. The south-facing aspect promotes greater pre- Termninaliasericea. Low shrubs includeAcacia hebeclada, cipitationand somewhat more even distributionthan Bauliiniamacrantha, Grewia spp., and Ziziphusmucronata. in the extreme southwestem Cape Province. Precipi- Generally, the densest tree and shrub growth is on the tation is altitudinally linked across a wide range from rises of sandy ridges; the depressions are more open. 500 to 1,500millimeters, moving from winter maxima Farther north, the vegetation becomes a tree and in the west to spring and autumn peaks in the east bush savanna with a slightly greater tree component This results in a fairly consistent phenology. It is low- in the vegetation, including Acacia spp., Bosciaalbi- est in June, July, and August, at about 0.38, and peaks trunca,Burkea ofricana, Combretum spp., Commiphora at about 0.5 in February and March. This is a some- spp., Crotonzambesicus, Loncitocarpus nelsii, Ockna what greater NDVIvalue than the otherfynbosvegeta- pzldzra,Peltophiorum africanum, Rius tenuinervis,and tion areas in Hill Shrubland and Bushy Shrubland TerminaliasericEw. These treesalso are more common on (Classes 32 and 33),perhaps because in this clissfiynbas sandridges,whereaslow-growingshrubsarecommonon enjoys partial protection from fire. Some of the floral the plains and include Croeonsubgnztissimus, Grewia spp., and biomass changes with elevation are described by Cminiphoapyrcanthides, and Xmeniacuffiu Rutherford (1972, 1978). These areas also are more The small outlier in southern Zimbabwe is parallet woody, with somewhat better growth conditions. to and just north of the Limpopo River, stretching They seem to be transitional from the Bushy Shrub- across the border between Botswana and Zimbabwe land (Class 33) to the "Warm Temperate Woodland" close to Beitridge. It is a degraded shrub savanna. in Class 67. Similar outliers exist in northern TransvaaL Here, the White (1983) suggests that Protea spp. bushes and seasonal winter drought is accentuated by soil of low other tal plants that often occur scattered in bushy inifitration capability and shallow rooting depths, fnbos may produce dense, impenetrable thickets 4 to plus pressure from nearby settlements such as Tuli in 6 meters high if they are protected from fire for long Zimbabwe or from land clearance and grazing, as is periods. This may apply in these areas. A wide vanety the case in the TransvaaL The vegetation mainly con- of species occurs, including restioid (for example, the sit of very low, shrubby Colophospermummopane up large Wildenounaasiata) and ericoid forms. while pro- to 5 meters in height, occurring as scattered individu- teoid shrubs also are commorLIn these areas of greater als, with a variety of Acacia spp., Bosciaspp., Dichros- NDVIvalues, certain shrubs and trees that are not true tachyscinerea, and ScLerocaryacaffra. The outliers in ]ynbosspecies locally formtthicket or scrub forest up to Mozambique can be classed as "Dry Riparian Wood- 10 meters talL These include Cassine peragua,Euclea land," with shrubs and small trees up to 5 meters tall tomentosa,E. undulaa, Maytenus heterophylla,Myrsine scattered in a grass-dominated savanna (Millington afrkcna,CiomnithWrusj itus, Pkmelastrutrcuspidatus, and others1989). Putterlixd pyrantha, Rhus spp., Tardonmnthuscamp- Much of this area, especially in South Africa, is honmtus,and Zygophyllummorgsana. Some encroachment given over to extensive cattle ranching. The carrying of Elytropappusspp. may occur. capabilityislow,however,commonlyasinglecowper The most westerly part of this land cover class oc- 6 to 25 hectares (Christopher 1982). curs in the vicinityofStellenbosch,Paarl,andWefling- The growing stock in this land cover dass is esti- ton, where vineyards are a dominant feature, together mated to be 137 million tonnes for southern Africa. with some olive growing. The more easterly parts The sustainable yield is estimated at 12 million tonnes include some sheep and cattle grazing and wheat a year, seriously limiting the potential for extraction. cultivation. The valley floors support citrus orchafds. It is probable that even a small rate of fuelwood extrac- For example, the Gamtoos Valley, possessing the most tion would exceed the annual rate of wood production. valued land of the region, is intensively cultivated. The thicket areas in this class have some fuelwood Class 42-Fynbos Thicket potential, but access islimited by land tenure patterns, and areas of commercial cultivation obviously have This land cover class is confined to a few small areas little fuelwood potential. Thus, despite an esthmated that trend east-west in the southern coastal ranges of 47 million tonnes of growing stock on this small area SotlwhernAfiica 147 of South Africa, the sustainable yield is estimated at to"HighveldGrasslndandfrom"AfromontaieScrub/ only about 0.5 million tonnes, so this remains an area Forest" to "Coastal Forest." The area lies chiefly be- of limited woody biomass resource. tween 800 and 1,700meters. The vegetation is mainly grassland, but originally was probably bushland with Class 43-Moist Acacia-Commiiphora patches of scrub foresL The relicts of this woody veg- Bushland and Thicket etationhaveAfromontaneaffinitiesathigheraltitudes and include Apodytesdimidiata and Hallerialucida. The This class covers 441,586 square kilometers of south- lowland remnants, whichare related to coastalforests, em Africa, more than 7 percent of this part. of the include Acacia spp., Aloe arborescens,Celtis africana, continent. It crosses many floristic regions, but they Commiphoraharueyi, Ficus spp., and Syzygium cordatum. are classified together by phenology and exhibit con- In South Africa, this land cover class borders the siderable ecological and structural similarity. The Highveld grasslands in the west and high-altitude class occurs in patches that formanarc extendingfrom woodlands in the east (for example, on the Lubombo the coastal plain of Angola, through southern Angola, Hills and forest plantations on the South African- parts of Zambia, Zimbabwe, and Malawi, to a south- Swaziborder). The grassveld on the higher areas often erly extension in southern Mozambique, southern is an open, grassy savanna with areas of bushes and Transvaal, and Swaziland. smaller trees, represented in moister areas by Acacia South Africa contains 111,767square kilometers of karroo,Maesa lanceolota,Syzygium cardaium, and Ver- this class, Mozambique 75,038square kilometers, An- noniaampla, and in drier areas by Acaciam7otica, Dichro- gola 71,224 square kilometers, Zimbabwe 63,498 stachys cinerea, Ficus capensis,Maytenus senegalensis, square kilometers, Zambia 55,067 square kilometers, and Sclerocaryabirrea. and Malawi 32,408 square kilometers, with smaller This class now- is largely an area of intensive com- occurrences in Namibia, Botswana, and Swaziland. mercialagricultureinthewest,especialyfromEnnelo All areas exhibit the broad characteristics of an open to Harrismith. This is mainly pastoral agriculture, but bushland or thicket, frequendy above a dense grassy with some maize and sorghum cultivation. Farther sward, but often this is considerably degraded or al- east and south, in Kwazulu and inland Natal, are tered by agicultural activity. considerable areas of subsistence agriculture. As a The phenology of this class has a distinct seasonal- result bushes and trees are very restricted by cultiva- ity, with summer Nm maxima (between December tion and grazing,-and woody vegetation now is con- and April) of 0.35to 0.47, followed by a fairly gradual fined to watercourses,poorersoils,andsteeper slopes. decrease to September (0.12), and a rapid increase In many areas, most notably Swaziland, lower reid fromNovember to December (figure 13-3).Most areas areas have been overgrazed and invaded by Acacia coincide with a mean annual precipitation within the nigrescens,with secondary Combretumzeyheri, Dichro- range of600 to 900 millimeters,usually withasummer stachys cinereass. africana,and Sclerocaryabirrea. The maxinum. trees can attain 10 meters height, and between them The largest contiguous area of this class occurs in are areas of low bushes, the most common being Cor- southern Transvaal, southern Swaziland, and inland dia g}haraf,Onnocarpum tuichocarpum, and Sclerocarya Natal This area coincides with two of White's transi- caffmrThese frequently are shorter than 4 meters, but tionalareas(1983):from"AfromontaneScrub/Forest" tree density is great, ranging frorn .25 to 625 trees per hectare. Eradication of this thomybushlandis difficult and expensive. This sort of bushy savanna- is both Figure13-3. NDvlProfile,MoistAcac-Conmiphorm widespread and currently extending, especialy in Bushland and Thicket (Class 43) Swaziland (ErCFoundation 1987). ln the Highveld and Middleveld of Swaziland, graz- 0.6- ing and cultivation have led to reduced woody bio- -43 Malawi mass and an increase in the proportion of grasses. This 0.5- also is true of the more western parts of this class in 0A4 \ - South Africa, including the small outliers on the mar- gins of the Drakensbergs to the south and east of c 03- \ - / Lesotho. z This class also occurs in Mozambique, mostly on .0.2- lowerhills facingthe coastinlnhambaneProvmce and on the slopes of the upper Save Valley, extending into southeastern Zimbabwe on south-facing slopes in - - Southern Matabeleland. Most of these areas are a low- JOanFeb Mar Apr May Jun Jul Aug Sep Oct Nov DCC woody-biomass tlicketlike form of the "Dry Minmbo 148 Estitttlig WoodyBiomass in S:ab-Saluaran Africa

Woodland" areas that surround them. Some are very Adansoniadigitata, Hyphtaen ventricosa, and Stercilia degraded, whereas others possibly are edaphic cli- spp. On low-fertility soils, either thicket or savanna max, dry thicket vegetation. The proportion of shrubs vegetation forms. Tllickets occur on alluvial soils to to trees varies from high thicket vegetation, in which the south of Lake Malawi; here the species are similar trees dominate and attain 10 meters in height, to low to those in wooded areas, although they are more thicket vegetation, in which shnibs up to 3 meters are stunted. On thin, stonysoils, a wooded savanna occurs more prevalent than the trees, which occasionally which is dominated by Bracihystegiaspp., Combrettun reach 8 meters. spp., Colopliospennunin mopane, and Pterocarpus spp. With decreasing height, the canopy becomes more Edwards (1982) quantitatively analyzed disturbed open and grasses and herbs increase. They are floris- savanna woodland near Blantyre. Compared with ma- tically related to mionbowoodland and the main tree htre miioa1bowoodland, this disturbed savanna wood- species are Acacianigrescens, Albizia spp., Brachlystegia land (a) lacks stratification, (b) has a significantly boehmii,and Izldbermardiaglobiflora. Some of these as- lower basal area (4.87 square meters per hectare sume a shrublike habit, but other shrub species also compared with 11.8 square meters per hectare), and invade the thicket vegetation. In northern Mozan- (c) has a better-developed grass layer. The main bique, this class largely occurs in the middle Zambezi dominants are Brachystegiaboehrnii, Burkea africana, Valley, following closely the 800-mirimeter isohyet, Jzlbernardiaglobiflora, Monotes aftricanias,and Pseuido- but small outliers also occur on the slopes of the upper laclinostylismaaproi neifolia. and middle Lurio Valley in the northeast. Areas of this class that occur in Zimbabwe are again A similar vegetation occurs in Malawi in the Shire largely on valley slopes, mostly to the north and west Valley north of Blantyre, on the Phalombe Plains, on of Harare (for example, on the flanks of the Hunyani the Shire Highlands, and over a large area north and Range). Patches also exist near the Mozambican bor- south of Lilongwe. Most of these areas are character- der, mainly on the sides of the Sabi Valley. As in other ized by very open woodland or a "Cultivation Sa- areas, such "Dry Savanna Woodland" (as it is called in vanna' (aterm commonly used in Malawi to describe Zimbabwe) is floristically poor and dominated by a savanna of mnaizecultivation and grassland with BracJystegiaspicjformisand ulbernardiaglobiflora, with very scattered miombowoodland and exotic tree spe- a number of smaller trees. cies). It generally grades from very open woodland to At its drier margins and in more disturbed areas, a grassy savanna in which the tree component often is however, the canopy can be as low as 3 meters and the represented onlybymangoes. Itmainly developsafter class takes the form of an open shrubby savanna. Here woodland clearance for cultivation and fuelwood the domninanttree is Brachystegiaboehmnii, with other extraction. small, invading trees and shrubs such as B. spicjformis, On very thin, stony soils, a dry, open-canopy Colophospennummopane, Julbernardia globifora, Kirkia miombowoodland is the natural vegetation. An exam- acuminata,and Sclerocuryacafra. Some of these areas ple is on the Rift Valley escarpment, where it is known may include "Escarpment Thicket," which is common locally as "Msuku Woodland." The main canopy along the entire length of the ZaambeziescarpmenL doniinants are Bracdystegiaspp., especially B. boehmii. This thicket rarely a: ains 10 meters height and forms In most areas, however, dry, open-canopy miombo a dense mixture of tree and shrub species, dominated woodland results from clearing well-developed by Combretumspp., Commipioraspp., and Pterocarpus woodland, and under increased population pressure antunesii. it grades into "Cultivation Savanna." Typical of this is In Zambia, a compact representative area of this the Lilongwe Plateau in Malawi, where the only rem- class exists in the Luangwa Valley and around Choma nants of open-canopy woodland are sacred grave- in the Southern District, together with scattered yards among grasslands and maize cultivation. The patches on the sides of the upper Zambezi Valley. In woodycomponentof the"Cultivation Savanna' away the Luangwa Valley, the vegetation is largely altered from these remnants is dominated bymangoes (Mangi- "MopaneWoodland." "MopaneWoodland" is usually fera indica), Acacia spp., Combretum spp., Piliostigma a single-story, open, deciduous woodland attaining 6 spp., and Lapacakirkiana. It is particularly common on to 18 meters in which the donminanttree is Colophos- the Lilongwe Plain and in the Namwera and Malindi pernm mopane.Although it often occurs as pure stands, regions (Nillington and others 1989). occasionally "Munga Woodland" trees invade, es- In the Southern Region of Malawi, population pres- pecially Acacia nigrescens, Adansonia digitata, Com- sureinthis class hasbeen far greaterthanfarthernorth bretum imberbe, Kirkia acuminata, and Lannea stuhl- and "Cultivation Savanna' and woody thickets are mannii. Shorter trees and shrubs usually are absent common. Fertile soils are characterized by grassland and the grass and herb cover is only locally dominant. interrupted by copses of relict woodland as well as It is restricted to alkaline soils on valley floors which isolated tees such as Acacia albida, Cordylaafiicana, flood in the wet season and are dry in the dry season. SouthlernAfrica 149

Destruction of "MopaneWoodland" leads to a drastic Class 51-Acacia Woodland Mosaic reduction in woody biomass because it is replaced by coarse tussock grassland. This class covers 519,892 square kilometers or 8.7 per- Farther west in Zambia, this class is represented by cent of southem Africa. Although best developed in areas on the slopes of the upper Zambezi Valley and Botswana, this class is distributed in an arc from north- its tributaries. It exhibits a similar Colophospermumn western Namibia, through Botswana, into southern mopane-dominated open woodland, but stands mixed Cape Province. It occurs in northern Botswana in the with CommipForaspp. and Terninalia sericeaare com- Chobe region to the east of the Okavango Delta, ex- mon and sometimes grade into the "BaikiaeaWood- tending north into the Caprivi Strip and a ound to the lands" on deeper alluvial soils near drainage lines. west of the Okavango Delta near Tsau. In southern The other compact outlier of this class around Botswana, it is strongly developed along the Bo- Choma consists partly of "Munga Woodland" tswana-South African border and in the Kalahari, (Fanshawe 1969).This is a type of savanna woodland with a number of significant patches south of the with an open, parklike appearance, with either one or Makgadikgadi Pan. It covers 97,012square kilometers two woody layers, dominated by Acacia spp.. Com- in Botswana. bretumspp.,and Terminaliaspp. in the upperstory and It also occurs extensively in Namibia (166,464 a dense woody understory reaching 4.5 meters. The square kilometers), with patches to the east of the bushes are deciduous to semiideciduous and are again Etosha Pan, in the Great Karas Berg, in the hilly parts dominated byAcacia spp. and Combretumspp.In some of Namaland, in the mnountainssurrounding Wind- areas of "Munga Woodland," woody thickets exist. hoek, and northward as far as the Angolan border. These are related to specific soil and water conditions, In South Africa, 142,277 square kilometers are and usually include Commiphoramolffs, Euphorbiacan- mapped in this dass; the principal areas are in dabr ,Markhamiaobtusifola,andSchreberntrichockla northern Cape Province and Bophuthatswana. Although it e-xhibits variations, "Munga Wood- Patches also occur in the Transvaal near Pretoria, to land" generally is an invasive secondary woodland. It the north and east near Potgietersrus and Pieters- appears to have developed by the invasion of wood- burg, and between the Drakensberg Ranges and land trees onto alluvial grasslands and all the tree Kruger National Park. Further small areas occur speces are fire resistant. Many other types of wood- scattered on the fringes of Veld Grassland (Class 11) land in Zambia are currently being invaded by in Orange Free State and southwestern Cape Prov- "Munga Woodland," in particular the riparian wood- ince. The southernmost representatives of the class lands. occur on the slopes of the coastal ranges, including In Angola, small areas occur in the southeast, sin- some areas in TranskeL ilar to those of western Zambia. The main areas are in Other small areas occur in southern Angola (25,768 the southwest, between Chiange and Otechinjan; on square kilometers), eastern and southern Zambia the west-facing slopes northwest of Lubango; and on along the Zambezi Valley (9,116square .JIometers), the slopes above Benguela and Lobito. These include and in northern Zimbabwe on the north-facing slopes the driest variants of the Angolanmiombo woodlands of the ZambeziValley. The classcovers 47,637 square and the "Eafidaeaand MopaneWoodlands." The can- kilometers in Zimbabwe. Other areas occur in opy trees are generally low, about 10 meters, and are Matabelelandand into eastem Mozambique on the sides mainly. Brackystegiaspp. and Julbernardiaspp. On of the Limpopo Valley(31,143 square ldlometers). higher ground, a variety of shrubby and stunted trees Nearly all of these areas are transitional between invadetoformabushythicket. Theareasfarthernorth Transitional Wooded Grassland (Class 24) and Open are floristically richer than the mionbo and "Mopane Woodland (Class 61), although in the south and west Woodlands," and dominantspeciesbecome Adansonia they often are adjacent to Wooded Shrubland (Class digitafa,Dichrostachysspp.,Euphorbiaconspicua,Setarha 35). This mosaic of Acacia woodland, Transitional welwitschii,and Sterculiasetigern. Wooded Grassland (Class 24), and Wooded Shrub- Land use in this class ranges from commercial cul-- land (Class35) is notasproductive as OpenWoodland tivation (for example, in parts of Malawi and South (Cliss 61). Its occurrences mainly coincide with those Africa) to subsistence farming (for example, Zambia areas that have an annual rainfall of 400 to 700 milli- and Swaziland). Pastoralism is inhibited by tsetse in meters, although it occasionally occurs in both drier many parts of Zambia and Zimbabwe. and wetter areas, depending on local soil-moisture The fuelwood potential of all these types of open holding conditions. woodland and thicket is significant, although limited Values of NDvi.are high, more than 0.36 between by the seasonal drought Woody biomass growing DecemberandMarchandpeakingat 0.42inFebruary, stock for southern Africa is estimated at 747 million with a slow decline from March to September when tonnes, with a sustainable yield of 9.1 million tonnes. the minimum of 0.17 occurs (figure 13-4). 150 EslivnalisigWoody Biiornass in Sutb-SalaamnAfrica

Figure 13-4. NOVIProfile, Acacia Woodland better developed and tree density is much grater. Mosaic (Class 51) Nevertheless, the canopy is generally open arid, espe- 0-6.- cially in the Colophlospennummopane-dominated areas, 0.6- the grass cover is usually poor. The trees usually are SI5Nonliem Botswana 0.5- less than 12 meters high, with average heights be- tween 7 and 9 meters. OA- The more open woodland in the north of Botswana is composed chiefly of Acacia spp., Cornbreturnspp., z 0.3 Tenninalia pnunioides,and Ziziphius mitucronata,with 0.2. shrubby Colophospernummopane, Grewiaflava, and T. sericea.In the northwest, scrub woodland occurs along 0. - the Ghanzi Ridge, which is rich in quartzite and lime- -*1 - . - stone and where vegetation is denser than in the sur- 0J F M A M J J A S O N C rounding.areas. Grasses are relatively unimportant Jan Feb Mar Apr Ma,yiu'n J'ul Aug Scp Oct Nov DeccI here, and shrubs are more inportant Trees include Acacia spp., Albizia anthelmintica, Boscia rehmanniana, In Botswana, bushland along the eastern side of the Combretum spp., Lonchocarpusnelsii, Montinia caryo- country comprises trees of small to medium height, phyllocea, and Pdtophorum africanum. A distinct grass- with a well-developed shrub layer. In the south, the land transition zone between dense and open wood- dominant tree is Peltophorumafricanum with Acacia land occurs around the Mabebe Depression; it is spp., Batuhinia macrantha, Boscia spp., Burkea africana, dominated by Cenchrus ciliarus and Chloris gayana. Ocdmapulchra, and Terminaliasericea.Farthernorth, the This land cover class continues into northeastern bushland is dominated by scattered trees of Acacia Namibia, including a large part of what White (1983) spp., Combretuim imberbe, Peltophorum afiicanum, -and classifies as the "Transition to Zambezian Broad- Sclerocaryncaifra. Among these trees are numerous leaved Woodland." ItisdominatedbyAcacia spp..,but smaller ones, such as AcaCia spp., Albizia spp., Boscia also includes Combretum collinum, Commiphora ai- albitrunca, Combreturn apiculatum, Commiphora schim- cana, C. angolensis, Ochna pulchra, and Ziziphus mucro- pen, Terminalia sericna, and Ziziphus mucronata The nata, forming a widely spaced woodland with trees main shrubs are Dichrostachyscinerea and Grewiaspp. normally less than 7 meters tall. To the north of the Tswapong Hills, the vegetation Farther. west, the largest occurrence of this class in changes both floristically and structurally as Colophos- Namibia is between Etosha Pan and Grootfontein, and permummopane becomes more important. This species along the Kaokoland Escarpment in the north (as well occurs both asa medium-height tree and in shrub form as other west-facing escarpments throughout Nami- It usually is the domriLnantspecies wherever it occurs. bia, which become drier at lower altitudes). Here Col- Associated treesinclude Aacia nigresens Burkea icana, ophospermummopane dominates the class at 7 to 10 Combretun spp., Commiphora nmssmnbiensis, Sclerocarya meters height and forms a light, stunted woodland caffra, and Terminalia prunioides.The most common with a shrubby understory on stony or sandy soils. shubs are Acadaspp., Commiphoapynrmdlmides, Dichro- Here and in Angola, where a number of small outliers stachyscinerea, and Grewiaspp. occur, the main associated plants are Acacia spp., - The scrub woodland to the north of the Tswapong Bosciamicropphylla, Combretum spp., Commiphoraspp., Hills in Botswana is the vegetation community with Greuna tillosa, Rhigozum spp., Terminalia spp., and the greatest woody biomass potential in this class. It Ximenia spp. has floristic similarities to Open Woodland (Class 61) In the Windhoek Mountains, a vegetation with sim- and is dom-Linatedby Colophospennummonpane. The as- ilar structure consists of tall bushes and small trees sociated trees have variable geographical distribu- over a grassy sward. The principal bushes and frees tions and may become locally dominant. They include are Acacia hebeclada,A. hererocusis,A. reficens, ATbizia Acacia nigrescens, Burkea africna, Comnbretumspp., Corn- anthelmintica, Combretum apiculatum, Dombeyn rotun- miphora mossambicensis,Kirkia acuminata,and Sclerocarya difolia, Euclea undulata, Ficus cordata, F. guerichiana,Hee- caffra.Accianigrescens and Burkeaafricana are the most ria (Oorez), Rhus marlotii and Tarchonantius camphoraus. common over large areas. The shrub layer consists of -Other areas of this class in Angola with a similar varying proportions of Acaciaspp., C mopane,Dkhro- phenology and productivity ocur in the upper tribu- stachys cinerea, Grewia spp., Tenninalia prunoides, and taries of the Zambezi Valley. These continue along the Ziziphus mucronata. flanks of the Zambezi Valley in Zambia. In Zambia, it The portion of this land cover class in easten Bo- is again "Colophospermummopane-dominated Wood- tswana differs-from that in the KalahariDesert and the land" with Acacia nigrescens, Adansonia digitata, Comn- northwest of the country in that the shrub layer is bretumimber, Kirkiaacuminata, and Lanneastuhhmnmnfi. SonilieniAfrica 151

C. nopanepreferssodium-rich soil in wetter areassuch fontein, Bethulie, and Wepener, and in the Orange as this, because it disperses the clay particles which Riverand Caledon valleys. These areas reflectmosaics then accumulate in the deeper horizons to form an of agricultural land within the natural veld vegetation. impervious layer, resulting in a small water storage Further small outliers occur in southwestern Cape capability and poor depth penetration. These occur- Province and Transkei as a transition zone between rences continue along the Zambezi Valley beyond the veld and the coastal range woodlands. Here, spe- Maramba and into northern Zimbabwe, south of Lake cies are more varied than those of Transvaal. In some Kariba. Further outliers occur in Matabeleland as, for cases they represent degradedwoodland, especially in example, south of the Matopo Hills facing the Transkei. Limpopo Valley. Most of these areas in South Africa have consider- In Mozambique, this class occurs on well-drained able agricultural activity, mostly cultivation of maize. sites above the floor of the Lirnpopo Valley and is In addition, these areas include sDme of the most represented by a mixture of "MopaneWoodland" and densely populated parts of the country. The woody. "rDryMiombo Woodland," often adjacent to Transi- component of the vegetation may be an important tional Wooded Grassland (Class 24). It also includes source of fuelwood for some rural populations. How- the dry riparian woodland along the Limpopo, where ever, this woody biomass often exists on privately the vegetation is essentially a grass-dominated sa- owned land, thereby restricting access. Elsewhere, vanna with shrubs (3 to 5 meters) and small trees (5 to these areas provide a significant fuelwood source, 10 meters). The species are related to the secondary most notably in northern Botswana and northwestern invasive tree and shrub species of the surrounding Namibia. woodlands. Fuelwood exploitation needs to be carefully moni- In South Africa, this class transcends a number of tored and controlled because of small sustainable floristic regions, but tends to occur on the margins of yield. Cattle grazing is an important consideration in the Veld Grassland (Class 11). In northern Transvaal, Botswana, where a carrying capability as small as one it coincides with the "Sour and Mixed Bushveldt of beast per 25 hectares (Millington and others 1989) Acocks (1975) and with White's "South Zambezian makes overgrazing commonplace. The drier southem Undifferentiated Woodland and Scrub Woodland' and western parts of this class are most prone to (1983).The soils of these flatter areas at altitudes of 500 excessive exploitation. to 1,000 meters are nutrient-poor, leached, and occa- sionally waterlogged during the wet season. Precipi- Class 61-Open Woodland- tation always exceeds 500 millimeters a year. A mosaic of dense woodland with grass understory This land cover class occupies more than 8 percent of is interspersed with more grassy patches in which southem Africa, nearly a half a million square kilome- Burkea africana,Termimalia sericea, and Ocmnapulchra ters. It occurs extensively in southem and-southeast- dominate the woody component, and Eragrostispal- ernAngola (127,944square kilometers), southwestern lens and Panicummaximum dominate the herb layers. Zambia (72,561 square kilometers) and northeastern The tall perennial grasses are mainly Andropogoneae Namibia (99,278 square kilometers), including the and havepoor nutitivevalue, especially in the winter; Caprivi Strip into the northof Botswana (24,767square hence the term "sour veld." Werger and Coetzee (1978) kIlometers). It then becomes a broken but extensive refer to these areas as part of the "Broad-Orthophyil band through central Zimbabwe (115,455square ilo- PlainsBushveld,'whichincludesthespedesjustmen- meters), curving southward into southern Mozam- tioned and Combretum apiculatum as dominant on bique (26,295square kilometers) and into small areas sandy soils derived from granite. They also refer to in northem Transvaal and Orange Free State (19,023 "TerminaliaSandveld'"communitiesinthedeepsandy square kilometers). Significant, although smaller, areas of the Transvaal, which are largely on the pla- areas occur in Swaziland (2,319 square kilometers) teaus and on small outliers in the low veld on granite and Lesotho (369 square ldometers). Although they soils. transcend a number of floristic groups (White 1983), Patches of this class also occur in northern Cape all these areas are classified together by productivity Province, and these have similar characteristics to oc- and phenology. currences in southern Botswana. Other outliers occur Open Woodland occurs mostly where precipitation along the south-f-acingslopes of the Kaap Plateau and ranges from 600 to 800 milLimetersa year with a sum- in the middle of the Vaal Valley between Prieska and mer maximumi. It also occurs in areas outside this Barclay West. Here, Acacia eriolobain particular has precipitation range, depending on soil drainage con- been removed from large areas to provide fuel for the ditions. In southeastem Angola, the phenology exhib- mines at Kimberley. Similar vegetation occurs in its NDVIpeaks of 0.42 in December and 0.38 in ApriL southem Orange Free State, in the vA-inity of Spring- dedining slowly to a mirimum of 0.21 in September. 152 EslimotingWoody Biornass ;i Swb-Sahamn Africa

In central Zimbabwe, a similar pattem is displayed, nant species characteristic of this class are Baikiaca with a peak of 0.36 in March and low of 0.2 in Septem- plurijuga,Surkea africana, Combretumn din teri,Guibourtia ber (figure 13-5). colcosperma,and Plerocarpusangolensis. Tree densities In the south and east of Angola, the seasonal of the dominant species ranged from 1.5 to 47 percent drought is manifest in scant annual rainfall and the for all trees, with 1.4 to 48 percent for trees 20 centime- longdry season. Thisseasonality isaccentuatedby the ters dbh (diameter at breast height). B. plurijuga forms soils developed on the KIalahari Sands and the thin, a canopy which can reach 20 meters, but is commonly stony soils of the Bid Plateau. The inability of these lower in drier areas; beneath the canopy is a rich, soils to hold water throughout the dry season subjects dense, shrubby understory (Millington and others the trees to a severe seasonal drought. This woodland 1989). differs from woodlands on the Angolan plateaus: it is The topography of ancient dunes on the Kalahari more open than Seasonal Miombo Woodland (Class Sands producesacharacteristievariationinvegetation 66),structurallydifferentfromWetMiomboWoodland patterns throughout the border areas of. Angola, (Class 67), and often floristically distinct from Ever- Namibia, Zambia, Botswana, and Zimbabwe. The green Forest (Class 82). ridges are tens of meters high and several kilometers The canopy trees are generally low (about 10 me- apart and are dominated by B. plunjuga, P. angolensis, ters) and are interspersed in a grass layer of up to 2 and G. coleosperma.Interdune areas are characterized meters height. On the Bie Plateau, the dominant trees by Combretuntspp. and Tenninaliasericea. A mixture of are Brachystegiaboehmii, B. gosswideeri,B. spicifornis, these occurs on the intervening slopes together with Julbernardiaglobiflora, and J. paniculata. On the high Erythrophieun spp. "MopaneWoodland" occurs on ba- parts of the plateau, between 1,900 and 2,200 meters, saltic areas and on alluvial soils such as those in the the canopy is much lower (less than 5 meters) and is Cunene Valley in southwestern Angola. dominated by B. floribunda, B. spiciformis,and J. pani- "Mopane Woodland" has the smallest woody bio- culata. However, a variety of other shrubby and mass potential of al Angolan woodlands, although stumted trees invades the high ground to formabushy the open woodland of the Kuando-Kubango District thicket. Above 2,200 meters, the tree species die out continues into northwestern Namibia and the Caprivi and the open thicket is replaced by "Montane Grass- Strip. In these areas, this class is composed chiefly of land." Acacia spp., Baikiaeaspp., Burkeaafricana, Combreaum The fuelwood potential of this woodland is far spp., Terminalia prunioides, and Ziziphus mucronata, lower than others in Angola, because both growing with some Colophospernumrmopane shrub. It occurs to stock and productivity are restrictcd. On the highest the north of the Acacia Woodland Mosaic (Class 51) parts of the plateau, fuelwood potential is extremely and has a somewhat greater productivity, although it small, but fortunately these areas are quite localized in is floristically very similar. extent In southeastern Angola, on the Kalahari Sands, In southwestern Zambia, these woodlands are re- where the.rainfall varies between 500 and 1,000 mii- ferred to as "Kalahari Woodlands" by Fanshawe meters a year, "BaikiaeaWoodland" and "Burkeaafiic- (1969),and include several types. "Guibourtia Wood- ana Savanna" occurs. land" is a two-story open woodland with a deciduous- In a forest feasibility study of Kuando-Kubango to-semideciduous, floristically rich upper canopy 18 District, Coelho (1967)identified seven forest zones in to 24 meters high which includes G. coleospenna,vari- the area covered by this land cover class. The domi- ous deciduous trees, and invasive "MiomboWood- land" species. The understory is composed of a high Figure 13-5. NDVIProfiles, Open Woodland thicket (13 to 2.6 meters) of small trees and shrubs. (Class 61) Climbers and scramblers are scarce, and the grass element is of variable density. 0.6- . "Burkea-ErythrophleuimWoodland" is a "Kalahari -61 SoutheasternAngola Woodland" that has a more open canopy than - 61 CentralZimbabwe -GuibourtiaWoodland,"and an unstratifiedunderstory.. 0.4- It is floristically less diverse and is dominated by Burkeaafricarna and Erythzrophzeumafricanum. Both of a cD3- these trees also exist in Guibourtiawoodland, and G. -col.spema also is common. Other trees common to D - both woodland types ae Amblygonocarpusandongen-

- . 1 - sis,Combretum mechowianum, Cryptosepalum exfoliatum, Dialiumengleranum,andMonotesspp. "MiomboWood-.

a- * I | | | I X . | | | t land" elements are rare in "Burkea-Erythrophleum Jan Feb Mar Apr May Jun Jul Aug SepOct Nov Dcc Woodland." Other types of "KalahariWoodland" are SouithernAfrica 153

mainly"Burkea-DiplorhyncliusWoodland 0 and"Diplo. Dirichictia rogersii, Pamspin barzcana, Pticlopsis an- rhynchusScrub." isoptem, and PterocarptusanilU1csii. lhe density of the These woodlands are all related, each'securing a shrub layer increases with repeated burning, and be- slightly different ecological situation. In general, they neath shrubby understories, grasses are poorly devel- have developed because of the destruction of natural oped. Baikiacaforests which now are restricted to the extreme The monlane vegetation in Zimbabwe is complex. southwest of Zambia. The Baikinea forest area has de- True montane forest, sirnilar to that in Malawi and in clined rapidly in recent yeare.due to cultivation, burn- East Africa, is rare, for two reasons. First, the Zim- ing,competition from Cryptosepalurnforest, and, most babwean mountains are generally lower. Second, important, timber extraction. B. pluinjuga("Zambezi many areas of southwestem Zimbabweare dry lee- teak") is a valuabletimber tree. The destructionof the ward slopes of mountainsthat form the border with forestleads to "Chipya"and other types of "Kalahari Mozambique.Consequently, Zimbabwean inontane Woodland" or to a secondary "BaikiaeaWood]and" forests suffer greaterdrought stress than the equiva- with elements from adjacent "Munga and KCalahari lent forest in Mozambique.Because of this, savanna Woodlands." woodland occurs to 2,100meters. The canopy rarely In Zimbabwe,this class includes the same "Open exceeds6 meters in height and is underlain by sparse Savanna and BaikiaeaWoodland" vegetation de- shrub, fem,and grasslayers. The canopy is dominated scribedabove, plus somemontane vegetation adjacent by Brachiystegiaspicifonnis, with occasionalareas of B. to areas of Evergreen Forest (Class 82). Much of this glaucescens,B. taxifolin,and Uapacakirkiana. classgenerallyexists onwell-drained soils above 1,350 In southem Mozambique,this class occurs in the meters, although it occursas low as 675 meterson the LiinpopoValley where it is a "Dry Miombo Wood- LimpopoEscarpment.The canopy is between6 and 13 land" with a maximum canopy height of about 8 to. meters tall and is dominatedby Brachystegiaspiciformis 10 meters. As it becomes drier it can be restricted to and fulbernardiaglobiflora. The tree canopy varies be- only 3 meters height and forms an open, shrubby tween 50 and 80 percent; shrub cover is open and savanna. This latter form is the more common. "Dry usuallybelow50percent,and grasscoverrangesfrom MiomboWoodland" is floristically poor and domi- 50 to 80 percent. An increase in the proportion of nated by Bracitystegia boehlmtii,B. spiciformis, and Julbemnardiaspp. is associatedwith increaseddistur- Julbernardiaglabflorn. Scattered among the canopy bance,usually afteragriculturalclearance.Witiin this are smaller trees of Monotes spp., Protea spp. and w oodland are patches of grasslands and savannasof Uapacaspp. Where the canopy is very disrupted, Acaciaspp. and Parinaricuratellifolia. Allof thesediver- shrubs commonlyinvade and a grass layer 0.6 to 1.2 gentvegetationtypesmaybeindicativeofdisturbance meters high develops. In these cases, the dominant or local environmentalconditions. The fuelwoodpo- tree is B. boeJmii, but other small trees and shrubs tential of these vegetation inclusionsis much smaller invade the canopy, such as Burkea africana,Faurea than the B.spiciformis-1. glabifiom woodland enclosing speciosa, Hymenocardia acida, Ocdna sclhweinfitrthiana, them. Parinaricuratellifolia, Swartzia rnadagascarienstis, Syzygl in In Matabeleland North, west of Hwange on the guineensess. gineense, Termdnaliabmchystenuna, and Van- deep Kalahari Sands, the class is dominated by an guenopsislancafolia. open, dry deciduous Baikiacaforest. The open nature In SouthAfrica, this land cover classis a versionof of the forest is again a function of its exploitationfor Acacia Woodland Mosaic (Class 51) having slightly agriculture, fuelwood, and timber. The B. plunju,ga greater productivity.It represents the denser wood- woodland canopy is extremely variable in height, land areas, with dominant species being Burkeaafri- ranging from a dwarf form (only 1 to 1.5 meters) to cana,Ochna pulcdra, and Terminaliasericea, along with regenerated specimens about 20 meters high. Other Combretumapiculatum on sandy soils. Much of this canopy trees are rare unless the area has been exten- class includes a mosaic of agricultural activity anrd sively disturbed. irrigationdevelopments. Examples include intensive At its edges, Baikiaeaforest grades into associated orchardsnorth of Nelspruit and around Zebwfielain woodlands and bushy savannaswhich containa mix- the Transvaaland irrigationdevelopments along the ture of tree species. Associatedwith B. p!arijugaon VaalRiver in OrangeFree State. deep, sandy substrates are Burkeaafricana, Entandro- In Lesotho,this land cover class is represented by phragma caudatum, Erythrophleum africanum, Ptero- pockets of bushy woodland along escarpmentsand carpus antunesii, and Ricinodendronrautanenii. The in- riparianareas. Along escarpments, the dominanttrees vasiveAcacia erioloba and Combretumcollinum also are are evergreenssuch as Diospyroswhyteana, Euclea spp., widespread.A floristicallyrich, dense,shrubby under- Halkerialucida, llex mitis, Maytenus spp., Olinia enar- stoy 5 to 8 meters tall exists,in whichthe main species ginata,and Podocarpslatifolius, with a few deciduous are Baphianassaiensis ss. obovata,Combretum engeni, species. In the riparian woodland component, the 154 EslinmtiigWoody Botimss in Sub-Sal)auan Afrien main woody species are Acaciakarroo, Ce1tis africana, are ecologicallysomewhatdifferent, buthaveasimilar Diospyroslycioides, Populusspp., Rtus fancea,Salixspp., phenology and productivity to Seasonal Miombo and Ziziphius niucronata. Generally, these are poor- Woodland. These coastal areas in South Africa and quality scrubby woodlands, known as shallahalila,and Mozambique coincide with White's "Eastern Africa are a product of overgrazing; however, they are an Coastal Mosaic" (1983) and with White and Moll's important source of fuelwood in Lesotho. "Tongaland-Pondoland Regional Mosaic" (1978). In Lesotho, this land cover class contains the largest These areas occurmostly whererainfall ranges from woodybiomassstock, but much of itis on escarpments 800 to 1,200millimeters a year, with a summer maxi- or along rivers and is inaccessible or has restricted mum. The phenology reflects the rainfail seasonality: access. In Mozambique, the sustainable yield is re- minimum winter NDVIvalues occur in August in An- stricted by seasonal drought. Although the class pro- gola (0.19),September in Zambia (0.22),and October vides readily accessible woody biomass in areas with in northern Mozambique (0.18).All three curves (fig- otherwise poor potential, the class is not a significant ure 13-6)show a rapid increase in NDVXvalues through long-term resource. the sprin& staying mostly above 0.40 through the In most of the other areas-Angola, Botswana, summer months. Peaks are 0.54 in Angola (Decem- Namibia, Zambia, and Zimbabwe-these woodlands ber), 0.55in Zambia (December andJanuary), and 0.52 have moderately high growing stock but smaller sus- in northern Mozambique January). tainable yield, so that only slow rates of exploitation Tropicalcoastal woodland areas ofSouthAfrica and are realistic if widespread vegetation destruction is to Mozambique have a peak NDVIvalue of 0.45in March. be avoided. Open Woodland does provide a poten- For the rest of the period from November to June, NDVI tially important fuelwood source, however, in many values range from 0.38 to 0.45. After June, levels-di- areas where surrounding lands are less endowed. The minish to approximately 0.25 from August through most favored sites are the "Montane Woodlands" of October, followed by a rapid rise through November- Zimbabwe, although many of these areas are reserved. December (figure 13-6). A potential conflict also exists between fuelwood and In Angola, Seasonal Miombo Woodland resembles timberextractioninmanyareasontheKalahariSands. Wet Miombo Woodland (Class 67), but has a more This class has an estimated 1,446 million tonnes of marked seasonality, a more open structure, and a woody growing stock throughout southern Africa, slightly lower productivity. Undisturbed Seasonal with a sustainable yield of 21 million tonnes. MiomboWoodland has a clear structure, a closed can- opy to 30 meters in height, and is floristica}lyrch. The Class 66-Seasonal Miombo Woodland main species are Brachystegiaboehmii, B. gosswieleri,B. (including Tropical Coastal Woodland) spiciformis,B. wangermeeana,Combretum spp., Isober- liniaangolensis, and Julbernardiapaniculata. A well- This is the largest of all land cover classes of southern developed tree layer at 5 to 10 meters occurs above a Africa, accounting for more than 1.3 million square dense- herbaceous undergrowth. Apart from rainfall kilometers, or about 22 percent of southern Africa. It amount and seasonality, the strongest controls on consists of well-developed seasonal forest to the south miombowoodland distribution in Angola appear to be of the Mesophilous Humid Tropical Forest (Class 85) vegetation disturbance, depth of soil, and altitude. and Ombrophilous Humid Tropical Forest (Class 87) In the dissected river valleys of the north, which of the equatorial areas. It is characterized by strong trend north-south, a rapidly regeneratingriparianfor- seasonality and asemi-evergreenordeciduousnature. Seasonal Miombo Woodland covers nearly the Figure 13-6. NDVIProfiles, Seasonal Miombo northemhalf of Angola and along theAngolanescarp- Woodland (Class 66) ment to the south of Huambo. Consequently, it xccurs in all districts except Namibe and Kuando-Kubango, 0.6- covering 450,070 square kdlometers. In Zambia, it is widespread, although more scattered, occurring in 0> every province and covering 344,891 square kilome------ters. It occurs in Malawi (46,425 square kilometers), across the north of Zimbabwe (78,252square kilome- a 03 v ters), and large areas of Mozambique (360,646square Z K NoribemAngola kilometers). - 0.2- ...... Smaller areas of mostly tropical coastal woodland in southern Mozambique, Natal, eastern Cape Prov- o. - 66 Nordem Mozambique ince (54,065 square kilometers total for South Africa) . 0 ------66 Mozambique coast andsmallpartsofSwaziland(4,479squarekilometers) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec SouithernAfrica 155 est occurs, 35 to 40 meters tall. On the drier interior globiflora,and Terminaliasericea appear with greater plateau, however, the forest is less productive and frequency in the canopy, The shrub and grass layers more sensitive to disturbance. Existingin northwest- also may be better developed. In the hills along the em Lunda Norte Province is a semi-evergreenwood- border of Zaire,in Northwestem Province,along the land of Marqucsiaacurninata-Pteleopsis diptera, 35 to 40 Mozambicanborder, and on the Zambian extensionof meters tall, although Marquesiarnacrazira-Brachystegia the Nyika Plateau, the trees come under severe taxifoliawoodland is more common. This is a succes- droughtstressduetothesmallerwater-holdingcapac- sional mnfombowoodland with a dense evergreencan- itiesof the thin, stony soils.Here the canopy is domi- opy of 30 meters height, dominated by the two trees, natedby Brachystegiaglaucescens, 8. microphylia,B. taxi- plus Brachiystegiaspp., Danielliaalsteeniana, Pterocarpus Wlia,and Cryptoseplum exfoliatum. angolensis,and Uapacaspp. A small tree and shrub The drier end of this class in Zambia is a "Dry layer also occurs, dominated by Brideliaspp., Erythro- MiomboWoodland" featuring both natural and disL- phleumspp., Fatureasaligna, Parinaricuratellifolia, and turbed elements. It is common on alluvial sands and Uapacaspp. It is likely that the miombowoodland inrBie flats, along the Zambezi Valley, the Cafue Flats, and, and Hula districts are similar to those in LundaNorte in part, on the Kalahari Sands. In the first two areas it District, is closely associated with "Munga Woodland." The In western parts of Bid, Cuanza Norte, Cuanza Sul, canopy of such woodlands is dominated by Ery- Malanje,Uige, and Zaire districts, wooded savanna- tlhrophleumafricanum, comnmonly with Brachystegiaal- type vegetation ismore commonthan woodland,with lenii, B. bussei, BW,ea africana,Isoberlinia angolensis, patches of bushy thicketand grassland,depending on -Jutbernrdia globi.lom,and4 Terminalia sericea. 'he wood- the environment. This is altogether drier and more land has a more open canopy of widely spaced decid- deciduous than the surroundingwoodlands. The dom- uous trees, enablinga diverse understory-to develop, inant species are Cochlospermumangolense, DiploJhyJuCs of which the common elements are Baphiamassaiensis, condylocarpon,Piliostigna thonningii, and Terminaliaseri- Combretum elaeagnoides, Crossopteryx febrifuga, cea. The shrub layer can develop into a thicketlike Dalbergiellanyasae, Diospyros kirkii, Diplorhynchus con- savanna, but usually only a well-developed tall grass dylocarpon,and Pseudolkchnostylismaprouneifolia. layer exists. "Munga Woodland" is commonon the KafueFlats, To the east, much of this land cover class is charac- in Southern District,and along the Lunsemjwa, lower terized by an open-canopy miombowoodland that is Luangera,and Zambezivalleys. It is a type of savanna floristicaUy poorer than wetter miombowoodland woodland with an open, parklike appearance. One or areas. In particular, Brachystegiafloribundais far less two woody layers exist, both deciduous, with emer- common or even absent locally. Other species of gents reaching 18 meters in height. Particularly imn- Brachystegiathat occurs in the wetter miombo wood- portantinthecanopyareAcaciaspp.,Combretumspp., lands are less important In most areas, particularly on and Tenninaliaspp. trees, although the woodland can thin or freely dramiing soils, Bracltystegiagosswieleri, B. be floristically diverse. Sometimes a dense understory spiciformis,and Julbernardiapaniculata dominate. reaching 4.5 meters occurs. The bushes are deciduous The stunted, shrubby understory of trees also in- or semideciduous and floristically diverse; but none- creases because more light penetrates through the theless, they are dominated by Acacia spp. and Comn- canopy. The grass and herbaceous ground layer also bretzm spp. Climbers occur occasionally, and a tall, is better developed. Nevertheless, in wetter areas, the thick grass layer always exists. It often is bumed canopy trees are very similar to the wetter miombo annually. woodlands. This land cover class also includes a degraded InnorthernBieDistrict,SeasonalMiomboWoodland miombowoodland, notably in the Kafue Flats and in is very poorly developed. The canopy varies between Luapala, Northem, and Northwestern provinces. In 6 and 30 meters height and the tree canopy cover these areas, woodland is destroyed by a type of shift- varies from 15 to 70 percent. The canopy is dominated ing agriculture practiced by the Bemba in Zambia by Brachystegiqtanxiindoides, Maniuesia )oadensis, Syzy- known as chitemene.It usually occurs in "Miombo or giumguineense,and Lapacaspp. The opennature of the Combretum Woodland." Mainly cassava, cowpea, canopy leads to a low tree and shrub layer (reaching 5 maize, and millet are cultivated, with groundnuts meters) and an open, grassy undergrowth- planted in the secend year. In Zambia, Seasonal Miombo Woodland is again The regrowth of abandoned plots has been studied closely related to Wet Miombo Woodland (Class 67) by Stomgaard (1985,1986), and is discussed in detail (Chidumayo 1987). The woodland is similar in struc- in Chapter 12 (EastAfrica).Overall, the sitaationis one ture, but it is more open and leaf loss in the dry season of declining miombo woodland species as they are is far greater. Species such as Bracdystegiaallenii, B. replaced by fire-resistant and fire-tolerant trees char- bussei,Burkeaafricana,Isoberliniaangolensis,Julbernardia acteristic of "Combretum Savanna.' The dominant 156 EstinialigngWoody Bbamnasshi Siib-Salhra: Africa trees are Bracltystegiaspiciformis, Combrehtm mecdio- south is largely a result of extensive clearance for uianiiuii,Diploriiyncdiuis condylocarpon, and Syzygium fueiwoodand cultivation. guineense.The canopy these form enables Unpacaspp. Undisturbed seasonal open-canopy rnioinbowood- to invade, and, much later in the succession, the main land occurs in northern and central Malawi, with an componentsoftheBmchystegia-Julbernardiawoodland open canopy dominated by Bmchystegia boelzmii,B. may reappear. Other vegetation types are common in mnanga,B. stipulata,B. spiciformis,Julbernardia globl4lora, the degraded SeasonalMiom1boWoodland; in northernm . paniculata,and Isoberliniato:nentosa. Once cleared, Zambia, these include "Itigi Forest' and "Lake Basin the nature and composition of the woodland changes Chipya Woodland." drastically. In the south of the country, three different "Itigi Forest" exists along the Zairian border near types of vegetation can be seen, which are described the Mweru Swamp. It is composed of deciduous trees in the following paragraphs. 6 to 12 meters high, mainly Bapltiamassaiensis, Boscia Slightly denser wooded areas occur on previously wngustjfolla,Burttia pnrnoides, Bussen nmassaiensis, Dios- cultivated soils that remain somewhat fertile, so that pyros mweroensis,and succulents. Underneath is a de- relict niiombowoodland and isolated trees occur in ciduous-to-evergreen thicket 3 to 4.5 meters high, patches. These contain mainly Acaciaalbida, Adansonia dominated by Bosciamossambicenmis and Tecleaisleri. It digitata,Cordyla africana, Sterculia spp., and palms, par- is a preclimax forest unable to attain dry deciduous ticularlyHyphaeneventricosa,between grassland areas. forest forms because of poor drainage conditions. In less-fertile areas, the vegetation degrades into Disturbance of 'Itigi Forest" results in the formation either a wooded or thicket savanna. Thicket savanna of "Lake Basin Chipya Woodland and Scrubland." occurs on alluvial soils in the lower Bwanje and Shire This is a thre-e story woodland with an open decidu- valleys and around the southem shores ofLake Malawi. ous canopy which can attain 27 meters height. The The tree species are similar to those in wooded areas, but main canopy dominants are Albiziaantunesiana, Burkea. all are much more stunted. rfticaa, Combretumcollinum, Erythrophleum af icanumn, On thin or stony soils, a very open wooded savanna Parinari curatellifolia,Pterocarpus angolensis, and Ter- forms, dominated by Brachystegiaspp., Colophosper- minalia sericea.This is underlain by a floristically di- mum mapane, Combretum spp., and Pterwcarpusspp. verse, evergreen-to-semideciduousunderstory,6 to 12 Considerable areas in this class are devoted to cultiva- meters high. The main dominants at this level are tion, including cotton, which is grown mainly along Cormbretumspp, Diplarhyndhuscondylocarpon, Markha- the Lower Shire Valley below 600 meters, and tobacco mia obtusifolia,Piliostigma thonningii, Pseudoladcnostylis which is generally grown at altitudes of 500 to 1,000 rnaprouneifolia,and Syzygium guineense. Under the meters in the Shire Highlands around Blantyre and middle story are a shrub layer, 2 to 3 meters high, and Limbe and on the Lilongwe Highlands. Other subsis- a rich ground flora, 0.6 to 2 meters high. It occurs tencecropsindudemaize,.cassava,millet,andrice,the extensively in Luapula Province along the Zairian last along the lake shores. border and around the Bangweulu Swamp. In Mozambique, this land cover class is an interme- In the north of Zimnbabwe,this class coincides with diate miombowoodland type, between the wet and dry a "Seasonal Savanna Woodland." In less-degraded phases This relation is clearly reflected in its geo- and moister areas, the canopy trees reach 8 to 10 graphicaldistributioninthe ZambeziValley.Innorth- meters and are dominated by a mixture of typical em Mozambique, it is representative of slightly drier Zimbabwean savanna woodland species, mainly Bra- conditions than in the surrounding Wet Miombo chystegiaboehmii, B. spicifornis, and Julbernardiaglobi- Woodland (Class 67), and in the south it represents flora, although other trees are invasive. Tree canopy wetter conditions than the surrounding "Dry Miomnbo cover varies between about50 and 80 percent, and the Woodland" and scrubby vegetation. shrub and grass cover is better developed. The under- In less-degraded areas, and in moister areas, the story is dominated by shrubs and smaller trees such as canopy trees attain 8 to 10 meters height, and, because Diospyroskirki, Faureasaligna, Protea gaguedi, Pseudolatch- of seasonality, are more open than WetMiombo Wood- noslis nUWmb/iLa, and Psorspenmumftbn4fum.Many land (Class 67). Small trees, shrub layers, and grass of these areas include tobacco cultivation, often grown layers are better developed. In more drought-prone in rotation withmaize, especially in the Harare regiorL areas, this woodland degrades into an open savarna In the north of Malawi, Seasonal MiomboWoodland with a well-developed herb and grass layer and is dominated by a denser, open-canopy woodland widely spaced trees to 8 meters; the canopy is domi- which exhibits a strong seasonality caused by climatic nated by Brachystegiaspiciformis and Julbernardiaglobi- or pedological factors. In the south, the woodland is flora. This class also includes the extensive tea planta- far more open and commonly grades into thicket and tions of Zambezia. wooded savanna, although some of it can be termed In southern Mozambique and South Africa, areas of open-canopy woodland. This poorer vegetation in the woodland along the coast and in some inland areas SoiltierntAfriM 157

have a different floristic composition but similar pro- In the mist belt forests of parts of the coastal and ductivity and phenology. These are tropical coastal interiorhighlandsof Natal, the maincanopycan reach woodlands, divided into five types by White and Moll 18 to 25 meters and emergents may attain 37 met-ers. (1978).Four of these-"Sand Forest," "Dune Forest," Lianas and epiphytes are rare, but a bush and herba- "Swamp Forest," and "Fringing Forest"-occupy ceous layer encroaches in more open woodland areas. edaphically controlled locations. The fifth, "Undiffer- On the coast, the wind-trimmed coastal thicket soon entiated Lowland Forest," is more widespread and gives way to a scrub forest with Cordiacaffra, Ekebergia consists of mixed evergreen and semideciduous spe- capensis,Euclea racenosa, Mimusops caifra,Sideroxylon cies of a height and stratification depending on local inenne,and Trichiliadregeana forming an open canopy site factors. over a dense, bushy understory. Canopy heights range from 10 to 30 meters with a In places on the rocky Transkei coast, Eurphorbia large number of woody lianas. Characteristic canopy triangularisforms a narrow fringe of scrub forest 10 trees include Albizia adianthifolia,Bractylaena spp., meters tall at the mouths of rivers. Scrub forest in the Cassipoureaspp., Celtis spp., Chiaetacmearistata, Comn- interior valleys is sometimes dominated by Aloe brethm kraussii, Drypetesgerrardii, Ficus spp., Millettia bainesii(12 to 15 meters tall) associated with a wide grandis, Mimnusopsobovata, Protorhus longgifolia,and variety of other species. The original forests would Trichiliadregeana. A widespread subcanopy layer ex- have extended along this entire coastal belt of South ists, with a wide variety of species; tail subwoody Africa, with the most luxuriant stands approaching plants up to 23 meters may occur. Many of these areas rain forest in stature and structure. The canopy would have beencleared, especiallyforsugarcane cultivation have been semi-evergreen to evergreen, with up to 30 along the coast of NataL - species represented in any one place out of approxi- "Sand Forest," which largely occurs to the south of mately 120 species for the entire region (White 1983). Maputo, has a deciduous habit occurring on sandy However, the remnants of such forests are few, and soils which are pale orange to grey, with rainfall be- those that exist are classified as Wet Miombo Wood- tween 700 and 900 millimeters a year. Here the forest land (Class 67) and Evergreen Woodland Mosaic is 10 to 25 meters high, with a canopy of Balanifes (Class 71). maughamii, Cleistanthus schleclteri, Newtonia hilde- Much of this class is a mnixtureof cultivation and brandtii,and Ptaeroxylonobliquum, with a well-devel- woodland. Cultivation ranges from commercial, as in oped subcanopy with Croton spp., Grewia spp., and the sugar plantations in Natal and tobacco estates of Ochnaspp. northeem Zimbabwe, to subsistence, most notably in "Dune Forest" is well developed north of Cape St. parts of Angola and Zambia. In Malawi much of the Lucia, with common pioneering species such as woodland is owned by tobacco estates, providing an Scaevolatiunbergii giving way to a full-canopy forest important accessiblefuel source for curing tobacco. Of which includes Diospyrosrotundifolia, Eucea natalensis, course, this limits access to fuelwood for others. and Mimusops caffra. In South Africa, mnanyforest reserves exist in the "Swamp Forest" occurs on wet sites near streams tropical coastal woodland, both on the coast and and lakes, but is now very limited in extent. The gen- inland. Some small areas have been given over to eral structure is a closed canopy of even height (about commercial forestry. Elsewhere, Seasonal Miombo 30 meters) with a sparse woody understory and a Woodland contains extensive growing stock, de- well-developed herbaceous layer. spite the strong lull in dry-season productivity. "Fringing forests" follow the Limpopo VaUleyin Where Seasonal MiomboWoodlands occur in associ- southern Mozambique. Common species include Eke- ation with drier woodland areas, they are important bergiacapensis. Fis spp., Ranolfiacaffia, Syzygium spp., source of fuelwood; but in wetter regions they may Trichiliaemehica, and Xanthocerciszambesiaca (White be less important than the surrounding Wet Miombo and Moll 1978). Woodland. Other patches of tropical coastal woodland occur Significant variations in growing stock occur be- southwest of Durban along the Umkomaas Valley tween different regions; for example, between inland of theDrakensbergs;around the coastnearPort eastern and westem Angola; between the smaller- Shepstone, extending inland to the Transkei border; potential "Munga Woodland" in Zambia and the along the "Wild Coast" at the mouth of the Umtata wetter Seasonal Miombo Woodland; and between the river in Transkei; and along the high ridge that forms more degraded areas of southern Malawi and the the border between Orange Free State and Natal, be- greater potential in northern MalawiL Estimated tween Ladysmith and Harrismith. These represent woody growing stock of this class throughout south- some of the better-preserved forest areas of the Tonga- em Africa is 7,463 million tonnes, with an estimated land-Pondoland floristic area recognized by White sustainable yield of 119 million tonnes, making it a (1983). very important resource, but one in need of careful 158 EstittalingWoody Biotiass inl Stib-Samnrain Africa management. It is about one-third of the woody is a response to cooler temperatures rather than resource of southem Africa. drought. In South Africa, these areas were classified by Class 67-Wet Miotnbo Woodland (including Acocks (1953)as "Valley Bushveld" and by White and Warm Temperate Woodland) Moll (1978) as transitional between "Afromontane" and "Undifferentiated Lowland Forests of the Tonga- In southem Africa, this land cover class occurs over land-Pondoland Mosaic." The natural woodlands about 7 percent of the land surface, an area of 409,916 vary considerably in luxuriance. Some have closed square kilometers. Two distinct and widely separated canopies with many trees at 20 to 30 meters in height, areacexist. WarmTemperate Woodland occurs on the but the majority of these temperate woodland areas coast of South Africa, covering about 23,500 square have a much more open and lower canopy and have kilometers. Wet Miombo Woodland stretches across been considerably altered by agricultural and other the SADCstates and covers more than 385,000 square land uses. At their driest end, which is usually accofn- kilometers. These two areas are discussed in the fol- panied by warmer temperature, they grade into lowing sections. FynbosThicket (Class 42). The tree flora is fairly uniform buthasa widevariety Warm Temperate Woodland of species, including Apodytes dimidiata, Combretu1m kraussii, Cryptocarya Iatifolia, Curtisia dentata, Halleria The South African area mainly occurs between licida, flex mitis, Kigeliaaftricana, Nuxia floribunda,Oc- Knysna in Cape Province and Kokstad in westem olea billata, Podocarpusspp., Prunus africana,Ptaero- Natal, although small areas also occur along the xylan obliquzun,Scolopia mundii, and Xyrnalosnionospora. coastal ranges of Natal and in the Drakensbergs of These arboreal communities exist today largely on Transvaal. This latter area includes one large expanse steeper slopes in valleys and in higher areas because stretching from just west of Uitenhage to east of Cra- much of the land, especially in Transkei, has been hamstown; it also includes significant highland areas severely degraded as a result of great population pres- in Ciskei and Transkei, between King William's Town sure. In addition, on rocky sites, sandstone outcrops, and Umtata and east of Umtata, from Mt. Frere down and unstable slopes, bushland is more common. With the UImzimvubu Valley to the "Wild Coast" near Port increasing altitude, ericaceous forms, especially Passe- St Johns. nna spp., Philippiaspp., and Widdringtoniaspp., dom- Annual precipitation in this class varies widely inate in a scrub forest of only 5 to 7 meters height. within the range of 500 to 1,500 millimeters a year, but The most southwesterly occurrence of this land usually is between 650 and 750 millimeters. The NDVI cover class is the Knysna Forest along the coastal area is close to 050 in the period from November to Febru- to the west of Port Elizabeth. This varies greatly in ary, exhibiting a slow decrease to a minimum of 0.27 stature and floristic composition in relation to slope, in August, followed by a rapid increase in the spring aspect, altitude, and soil moisture (Taylor 1978). At (figure 137). The summer maximum is a vegetative lower altitudes, where temperatures are warmer and growth response to precipitation and warmer temper- droughts are more common, this class grades into atureincoastalSouthAfrica,andthewinterminimum scrub forest, 1-ushland, and thicket, with dominant species being Diospyrosdichirophyjla, Eudea racemosa, Grewia occidentalis,Maerma aifra, Sydemoxyloninerntc, and Rhus Spp. Figure 13-7. NDVI Profiles, Wet Miombo Woodland At higher altitudes, with decreased temperatures (Class 67) and increased humidity, canopy height again falls off rapidly, and forest gives way to scrub forest and 0.6 thicket. The main species are Berzelia intennedia, Diospyrosglabra, Leucadendroneucalyptifolium, Protea 0.5 .4/- cyntrnides, and Virgilia oroboides.Many areas of this 0.4 % \ - Z - -class are mosaics of agriculture, orchards, afforested areas, and natural woodlands. This is true of areas o 0.3- north of Nelspruit, in the coastal ranges of Natal, and z - near East London, where the mosaic of agricultural 0o2 land and warm temperate coastal forest extends to the - 67 Zambia "Wild Coast." 0.1 -67 SouthemAfuican cont This dassis an important sourceof fuelwoodin the 0- I I I I- , ,Ir-,T,-,- , densely settled Transkei uplands, where it is exten- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dcc sively exploited. There is a marked contrast between SoIlJIIrnAfnicn 159

canopy, often floristically rich, with a dense, closed fuelwood in the Transkei and attaining 30 me- the accessibility of exceeding 15 meters but capable of Ciskeicomparedwiththeequivalentareas,oftencom- by Brachtystegiaboehmnii, B. gos- Province. The teTs. It is dominated mercially managed, in adjacent Cape B.wangerinecana, Combretum spp., regions is esti- wuieleri,B. spiciforntis, woody biomass growing stock in these andJulbernar- with a sustainable Cussoniciangolensis,Isoberliniaangolensis, mated at about 74 million tonnes, diapaniculata. a well- yield of 1.3 million tonrnes. canopy trees are less common, but Other 5 and stunted tree layer exists at between developed is well Wet Miombo Woodland A herbaceous undergrowth also 10 meters. Uapaca Within the woodland, stands of of this class occupies developed. a The Wet MiombaWoodland part 4 to 10 meters high. These indicate area of southem forest occur, clear- approxinately 6 percent of the land vegetation following agricultural square kilometers. successional the Africa, an area of more than 385,000 ground in the Bie Plateau, squarekilome- ance. On the higher Itcovers large areas in Angola (150,234 is lower (6 to 25 meters) and more where it includes woodland canopy it is ters), especially in northern Angola, varies from 30 to 90 percent). Here northeast of the coun- open (cover B. the Dernbos cloud forest in the by Brachystegiabakerana, B. Iotigifolia, border between Bi and dominated col- try and large areas on the Copaiferabaumiana, and Guibourtia Malanje. It occurs spiciformis, layer Moxico, in Lunda Sul, southeastern There is a low (0.5 to 2 meters) woody extends across the Zambian eosperma. a dense, tall in eastem Moxico and 50 to 60 percent ground cover and Province. with border into Northwestem grass layer (2 to 3 meters). it occupies a considerable northeastern es- Elsewhere in Zambia, The Dembos cloud forest on the Central, Latlipula, and Lusaka Angola between portion of Copperbelt, carpment of the central plateau of areas scattered in Northem, in this land cover provinces, with smaller 6030' N and 9030' N also is included provinces, totaling 102,967 less moisture Southern, and Western class. Cloud forest vegetation exhibits Malawi has significant occur- and plateau square kilometers. stress than that on the adjacent lowlands the shore of Lake Malawi and at precipitation rences, mainly along due to the frequent mists and increased 7,694 square kilomieters. Im- the moisture- high altitude, totaling (1,100 to 1,500millimeters a year) from exist on either side of the Zambezi reaches be- vortant areas also laden onshore winds. The forest canopy and Zimbabwe. Smaller patches very rich. River in Zambia tween 30 and 50 meters and is floristically in Matabeleland, and spp., Celtis spp., occur in westem Zimbabwe, The main canopy trees are Albizi of the Sabi cathdment, extend- is used extensively along the higher slopes Ficusspp., and Mous spp. The area coffee grown under the ing into Mozambique. of for coffee cultivation, with the covers 22,606 square kilometers The class in shade of the large canopy trees. In Mozambique, it occurs extensively this category in eastem Moxico Zimbabwe. River and The woodlands in north, particularly along the Luganda and floristically related to the Delgado and Province are ecologically along the northern coastal areas of Cabo Zaire and western Zambia. These on the east-facing those of southern Nampula provinces. It also occurs highly variable and responsive to soil one smal occur- woodlands are slopes in Manica and Sofala, with quality. On well-drained soils, various It covers 10,861 depth and de- rence on the coast near Inhambane. of "Miomboand CnyptosepalumWoodland" types macropkylla square kilometers in Mozambique. On the thinnest soils, Brachysfegia that fairly highNvi values velop. of B. spici- The phenology indicates B. utilis dominate. Closed woodlands from October to June with and exhibit (0.42 to 0.54) are sustained also exist, and thicker, well-drainedsoils 0D4inNovember.Thelowest -fiis pilosaWood- apeakof approximately either open "Marquesiacalonerus-Uapaca occur in August and Septenber, mara- vtvivalues (026) land' or, more commonly, dense"Cryptosepalum in October (figure 13-7). This re- bave high increasing rapidly vienseWoodland." All of these woodlands usually greater than 1,000mil- vary considerably flects the high rainfal, canopies of 15 to 20 meters, but they summer maximum, and a limited dry vegetation. On limeters with a in canopy openness and understory Chidumayo (1987) divides the of the woodland is period in the winter. the poorlydrained soils, the height of Zambia into wetter and drier boehmii,Marquesin miombo woodland less. It is dominated by Bracdystegia milimeters rainfall a year. places, however, types at about 1,100 kIalngensis,and Uapacaspp. In many these areas were classed by Erc Founda- into a grassland with In Angola, "Dense this low woodmand develops and Millington and others (1989)as tion (198) from very poor fuetwood potential. Miambo Woodland." It differs Woodland is generally a Medium Height in I' Z am'bia, Wet Miombo Woodland Mosaic (Class 71) slightly woodland. The Evergreen although two-story, closed, semi-evergreen seasonality and in less overall productivity, dominants are Bracstegia spp, Iso- with similar species main upper-story it is denser and wel wooded, ulbemardia spp., and Pteroacorpusangolen- structure and is berliniaspp., composition. It has a well-defined Soul/tmrAfrco. 161

Outliers of the class exist in Mozambique, in Tete (1967),which is describedin more detail inMllington and Niassa Provinces in the north, in the extreme and others (1989) This area differs from that farther northeast, and along the coast. of Inhambane and north because the trees are related to Open Woodland Gaza, especially near the mouth of the- impopo. (Class 61), with which this class interdigitates in the Other outliers occur on the border between Mozam- south. The most common tree from Open Woodland bique and Zimbabwe in Inyanga National Park. Still (Class 61) is Burkeaafricana, and generally, the Ever- other small outliers occur in Malawi (,635 square green Woodland Mosaic here is dominated by Idlometers) and in parts of Northern Province in Zam- Brachystegibakevkna, Cryptosepulum pseudotaxus, Ery- bia (6,060square kilometers). thtrophleurnafrlcanum, Guibourtia colcosperma,and Evergreen Woodland Mosai suffers little, if any, Isoberliniaspp., especially L. baumii.The canopy be- seasonal moisture stress This. may be the result of comes more open on the shallower soils of the Bie reliable precipitation and local soiLmoisture condi- Plateau and as the Open Woodland (Class 61) bothe tions. Its "evergree" nature, however, is more likely south Is approached. the result of understory leaf growth during the short In Mozambique, the Evergreen Woodland Mosaic periods when upper-canopy trees are relatively leaf- is best developed adjacent to the coast in Zambezia less. This "evergreen behavior is illustrated in the and Sofalaprovinces.The coastal pLainisflat and often phenology.Photosynthetic activity is high throughout marshy, with large areas periodialy flooded. Litle if the year, mostly varying between mmVtvalues of ap- any seasonal moisture stress occurs. The canopy proximately 0.35 and 0.55. High productivity is sus- reaches to more than 15 meters, but more commonly tamedbetweenNovemberandJulywithabriefperiod is about 10 meters and is underlain by a layer of low. of lowproductivity between August and October (fig- trees (5 to 10 meters high) and a poorly developed ure 13-8). herbaceous layer. The canopy is dominated by In Angola, this class was termed Dense High Brachystegiaf m and Juiberiar globufiam,but Miombo(sc Foundation 1987;tMingon and others the whole woodland is floristicallyvery rich. 1989).Ithas a very well defined strucure and is flors- The coastal forest belt is characterized mainly by a ticaDy richL Ihe canopy, which often extends to 25 dry, deciduous forest on the lowland plains, with meters, is dense and often closed, although not al-. moister evergreen and semideciduous forest on the ways. It is dominated by Bractystegia kruna, Crypto- windward mountain slopes. The evergreen and semi- sepaiwnexliatum, Dialum engemnwn, Guib&ta col- deciduous component of the coastal forest complex is eospma ss. pseudotam, and Julbernardiapaniculata. grouped in this land cover class. Much of this forest Few other canopy trees occur, but stunted trees grow has now been converted to low woodland (MIliington to between 5 and 10 meter This lower layer is domi- and others 1989) with an upper canopy of 10 to. 12 nated by Baphiamassaensis, Copaftm bawniana,Dios- meters and a lower canopy of 5 to 7 neters and is pyros spp., Paropsiabrwna, PaHnarispp., Tichilia dominated by Acacia nigrescensand Albizia spp. In qwdrensis,and Xylopiaodoratissi ma , many areas it has become so degraded that it now In addition to thuse two tree layers, a very poorly fornis a tudketike vegetation with shrubby species developed grass and herbaceous gromd layer exists. varying between 3 and 7 meters in height and emer- Detailed data on the composition of Evergreen Wood- gells of up to 10 meters. landMosaicinKuando-KbangoDistrictare available Not all of te lower forest and thidket can be attr- in the forestry feasibility study carried out by Coelho uted to degradation, because low, open vegetation occurs naturally on sandy soils of low water-holding hgure 13-8 mmVProfiles, Evergreen Woodland capabilty along the coast (for example, Inhambane Mosaic (Clasc 71) Province). Scattered pockets of higher, nondegraded coastal forest still exist, although much is degraded. 0.6- These forests have a canopy of about 20 meters, with emergents reaing 40 meters. The main species are -_S05- \ X-, Crossoneh&s (Melanodiscs) oblgs, La= szyne- 0.4 / tonji,and Maranthesgoetzniaa In Manica and Sofala provinces, and on the wind- 03-S . . \ // . ward slpes of the Macondes Plateau, the moister forest is semideciduous rather than evergreer It has a -0.2- -V.-- canopy of about 15 to 20 meters with emergets up to - 71 CCII - -A. 35 meters, the mean height of the larger frees being - 71 Wzambiwe wm about 25 meters. The main canopy species are -- Eryhropkwn surneolens, NeaJtora buchananj, and Jan Fcb Mar Apr May J., Jul Aug Sep Oct Nu Do Pachystelabreipe A well-developed shrb layer con- SoLin(trerAfrica 161

Outliers of the class exist in Mozambique, in Tete (1967),which is described in more detail in Millington and Niassa Provinces in the north, in the extreme and others (1989).This area differs from that farther northeast, and along the coast of Inhambane and north because the trees are related to Open Woodland Gaza, especially near the mouth of the Limpopo. (Ciass 61), with which this class interdigitates in the Other outliers occur on the border between Mozam- south. The most common tree from Open Woodland bique and Zimbabwe in Inyanga National Park. Still (Class 61) is BIirkcaafricana, and generally, the Ever- other small outliers occur in Malawi (2,635 square green Woodland Mosaic here is dominated by kilometers) and in parts of Northern Province in Zam- Bradcystegiabakerana, Cryptosepalurn pseudotaxus, Ery- bia (6,060square kilometers). thtrophleurniafricanumi, Guibourtia colcosperma, and Evergreen Woodland Mosaic suffers little, if any, Isoberliniaspp., especially L bautnii. The canopy be- seasonal moisture stress. This may be the result of comes more open on the shallower soils of the Bid reliable precipitation and local soil moisture condi- Plateau and as the Open Woodland (Class 61) to the tions. Its "evergreen" nature, however, is more likely south is approached. the result of understory leaf growth during the short In Mozambique, the Evergreen Woodland Mosaic periods when upper-canopy trees are relatively leaf- is best developed adjacent to the coast in Zambezia less. This "evergreen" behavior is illustrated in the andSofalaprovinces.Thecoastalplainisflatandoften phenology. Photosynthetic activity is high throughout marshy, with large areas periodically flooded. Little if the year, mostly varying between NDVI values of ap- any seasonal moisture stress occurs. The canopy proximately 0.35 and 0.55. High productivity is sus- reaches to more than 15 meters, but more commonly tainedbetweenNovemberandJulywithabriefperiod is about 10 meters and is underlain by a layer of low of low productivity between August and October (fig- trees (5 to 10 meters high) and a poorly developed ure 13-8). . herbaceous layer. The canopy is dominated by In Angola, this class was termed Dense High Brachystegiaspiciformis and Julbernardiaglobiflra, but Miombo(EIc Foundation 1987;Millington and others the whole woodland is floristically very rich. 1989).Ithas a very well defined structure and is floris- The coastal forest belt is characterized mainly by a tically rich. The canopy, which often extends to 25 dry, deciduous forest on the lowland plains, with meters, is dense and often closed, although not al- moister evergreen and semideciduous forest on the ways. it is dominated by Brachystegiabakena, Crypto- windward mountain slopes. The evergreen and semi- sepalumexfoliatum, Dialium engleranum, Guibourtia col- deciduous component of the coastal forest complex is eospermass. pseudotaa,- and Julbernardiapaniculata. grouped in this land cover class.Much of this forest Few other canopy trees occur, but stunted trees grow has now been converted to low woodland (Millington to between 5 and 10 meters. This lower layer is domi- and others 1989) with an upper canopy of 10 to 12 nated by Baphiamassaiensis, Copafera baumiana, Dios- meters and a lower canopy of 5 to 7 meters and is pyros spp., Paropsiabarzzeana, Parn?ari spp., Trichilia dominated by Acacia nigrescens and Albizia spp. In quadrensis,and Xylopiaodoratissima- many areas it has become so degraded that it now In addition to these two tree layers, a very poorly forms a thicketlike vegetation with shrubby species developed grass and herbaceous ground layer exists. varying between 3 and 7 meters in height and emer- Detailed data on the composition of Evergreen Wood- gents of up to 10 meters. landMosaicinKuando-KubangoDistrictareavailable Not all of the lower forest and thicket can be attrib- in the forestry feasibility study carried out by Coelho uted to degradation, because low, open vegetation occurs naturally on sandy soils of low water-holding Figure 13-8. NDVI Profiles, Evergreen Woodland capability along the coast (for example, Inhambane Mosaic (Class 71) Province). Scattered pockets of higher, nondegraded coastal forest still exist, although much is degraded. 0.6 These forests have a canopy of about 20 meters, with emergents reaching 40 meters. The main species are o.s- Crossonephelis(Melanodiscus) oblongus, Lovoa swynner- 0.4- kn/toii, 1 andMaranthesgoetzeniana. In Manica and Sofala provinces, and on the wind- > 03- ward slopes of the Macondes Plateau, the moister forest is semideciduous rather than evergreen. It has a 02- canopy of about 15 to 20 meters with emergents up to 71 Centl Angola 35 meters, the mean height of the larger trees being -71 Mozanbique coast about 25 meters. The main canopy species are o- Eryropzhleum suaveolens, Newtonia buchananti, and Jan Feb MarApr-Jap FcMay yj.m~g Jun JuE Aug Se'pW Oct Nwo De Pachystetabrevpes. A well-developed shrub layer. ccon- 162 EstimulingWoody Biomiass in Sub-Snhnmn Africa tains Albizia adianthlifoliaas the main species. Varia- resource. Representatives of the class in the Cham- tions to this general pattern occur, particularly around beshi Valley remain an important source of fuelwood. the Zambezi Delta, where "HirtellaForest" develops as a response to greater precipitation (1,200 to 1,400 Class 72-Cultivation and Forest/Woodland millimeters) and a high water table. "HirtelIaForest" Mosaic is a mosaic of Miombo Woodland and Semideciduous Ptelcopsis-ErythmopileutmForest, and is dominated by This class covers nearly 3 percent of southem Africa, Hirtellazanzibarica. Rice and sugarcane are grown ex- an area of 163,250square kilometers. It occurs mainly tensively in these coastal plain areas. - in areas with special drainage characteristics and in- In Malawi, this land cover class coincides largely cludes considerable cultivated land. The most distinc- with a mosaic of miombowoodland and cultivation tive occurrence is the Okavango Delta area in north- along the lower land adjacent to the westem shore of westem Botswana, with an associated small area on Lake Malawi, but it also includes montane areas such the Chobe River on tthe Botswana border, together as those around Mount Mulanje. FloristicaUy and covering 16,441square kilometers of Botswana. structurally, it is similar to the miomnbowoodland de- Most other areas are less compact and scattered to scibed in Classes 66 and 67, with the canopy being the north and west The majority occur in a circle of dominated by Brachystegia boehmii, B. manga, B. patches fringing the Evergreen Woodland Mosaic stipulata, B. spiciformis, Julbernardia globiflora, J. (Class 71)incentral Angola (99,172squareldlometers). paniculata,and Isoberliniatomentosa. B. boehmiiis the The largest of these areas is in Kwanyama in southern dominant tree species in many areas. This land cover Angola, with another large area on the southeastem class is intermediate between Wet MiomboWoodland slopes of the Morro de Moco, northwest of Huambo. (Class 67) and Evergreen Forest (Class 82). Other smaller areas are associated with south- -This land cover class is also represented innorthern ward-flowing tributary streams and occur in associ- Zambia by the vegetation associated with swamps, ation with the Zambezi and its tributaries in western lakesides, and wet valley floors. Many of these areas Zambia. Small areas exist in the extreme northwest are grassland, but some are areas of swamp forest. of Zambia around Mwinilunga on the River Lunga, These are mainly three-story dosed evergreen forests so that altogether this class covers 29,193 square with a canopies readcing 27meters, dominated by flex kilometers of Zambia. Small areas occur in north- mitis, Syzygium spp., and Xylopiaspp. They are under- western Nairibia, associated with the ephemeral lain by a discontinuous evergreen understory of 9 to drainage of the Omatako (9,801 square kilometers). 18 meters and a dense evergreen shrub layer which Other areas are on the Zambian-Zimbabwean bor- reaches4.5meters.Theforestflooriseitherbareorhas der on the shores of Lake Kariba (Zimbabwe has stands of herbaceous vegetation. 2,582 square kilometers in this class) and on the All swamp forests are controlled by high ground- border between Botswana and Transvaal on the water levels and are small, varying from 1 to 120 Limpopo, near Martin's Drift (South Africa has hectares. Fanshawe (1969) estimates that only 380 -5,270 square kilometers in this class). sq uare kilometers of swamp forest exist in Zambia. The phenology of this land cover class exhibits a Otherareasofthislandcoverclassoccurinvalleyfloor limited seasonality, with NDwvrpeaks of .27 to 0.35 sites, notably the Chambeshi. These are floristically between February and May, followed by a slow de- and structurally similar to those described in the adja- crease to below 0.2 between July and October. The cent Wet Miombo Woodland (Class 67), but with a Okavango Delta area shows somewhat greater sea- somewhat different phenology. sonality, with a marked peak of 0.37 in December and For most areas in this class, growing stock is high, January, slowly decreasing to 0.12 in September. This as is sustainable yield. Overall, in southern Africa, the is followed by a sharp increase through October and esbtmated growing stock is 83 million tormes, with a November to December (figure 13-9). Moisture avail- sustainable yield of 3 million tonnes. The high grow- ability seems to be the key to this seasonality; this can ing stock and sustainable yield mean that, in most be influenced by the level of the water table as well as places, the fuelwood potential of these forests is great precipitation. This is the case for most areas in Angola and Mozarn- A more compact area of this class occurs in the bique, but areas in Malawi and Zambia are more vari- Okavango Delta, with small outliers in the Chobe able. In many parts of Malawi the areas are either Valey on the Namibian border, notably around the associated with lakeside cultivation or are confined to large southen meander of the Chobe River. It is partly less-accessible montane woodlands. In Zambia, al- a fringing forest with floristic similarities to the sur- though they have plentiful growing stock, the swamp rounding woodland types, as well as having species forests are important only locally as a woody biomass adapted to the edaphic conditions. The class exhibits SouthlernAfrica 163

FigUre13-. NDVI Profiles, Cultivation and Forestf White (1983) refers to thickets dominated by Woodland Mosaic (Class 72) Brachystegiahbakera-na,somnetimes no more than 1.3me- 0.6 ~~~~~~~~~~~~tersin height although usually taller, occurring as an -72Angola Snulham ~ecotone between hydromorphic grasslands.and o- 72woodlands on better-drained sites. Well-developed. - 2Okovoago.Bmwwana forestinaydevelop along the largerwatercourses,and D4- most of the. tree species are deciduous for at least 2 months of the year. The floodplain of the. upper zZabzinBrteadifloeeahyerfo0.3-~~~ ~ ~ ~ ~ ~~~abz nl3rteadi loddec erfo 0.2- ~~~~~~~~~~~mid-Februaryto mid-June to a depth of 2 meters or more. Few tree species can withistand such a pro- 0.1- nountced fluctuation in water level,-arnd the outer ______fringe of riparian forest, 9 to 12 meters tall, is domi- JanMy eb Jn arJu Ar Au Se OctNovD nated by Syzygiumguiineense ss. barorsense,with an understory of RJiusqua rtintiana. Some thickets in this class occur as regenerative the greatest productivity of any class iBotswana, but stages after disturbance from overgrazing, shifting is also characterized by some seasonal vRLiationin cultivation, or fire. Or, they may occur on certain soils, productivity. Around the Okavango Swamp, grass- such as loamy sands that have clayey. impervious land is fringed by a belt of large trees such as Acacia layers at depth. erioloba,A. galpinil,A. xanthophoioea,Cola plwspermumn Woody biomass stock and productivity may appear mopane, Combretum imberbe, C. megalobotbys,Croton ample in this clans, but accessibility problems exist in megalobotnjs,Diospyros mespiljfonnis, Ficus sycomorus, many areas. Many areas are remote arnd,for much of and lonchocarpuscapassa. The grassy Chobe floodplain the year may be flooded. Some areas are given over to has a similar fringe of woody vegetation, but some cultivation. Some areas, like Chabe and Okavango, lie areas are given over to cultivation, partly in national parks. This class is, therefore, of Although not as dlearly linked to a particular soil. miixedpotential for fuetwood. moisture regime such as the above, areas with similar biomass and phenology in Angola and western Zam- Class 82-Evergreen Forest bia owe their existence to seasonal flooding. Large areas are periodically flooded by the Zambezi and its This class covers about 5 percent of southern Africa, tributaries, as well as many other rivers that drain an area of 313,906square kilometers.It consists of two north and south from the central highlands of Angola. principal types of forest. The larger category consists During several months of the year, the water table is of high-altitude miombo woodland that extends in close to the surface, promoting a short, tufted grass- patches across Angola, Zambia, Zimbabwe, and Mo- land with thicket on nearby nonflooded sites; the most zambique. The smaller category consists of afforested abundant grass is Loudetia simplex. In Kuando- areas and natural woodlands in subtropical South Kubango in southern Angola, such grasslands, inter- Africa. It includes large areas of west-facing slopes on rupted only by thickets, cover large.areas. coastal mountains in Angola, stretchLingfrom Zaire These areas often are flonistically transitional be- Province in the north to the Serra da Che-laescarpment tween "'Baikiaa and MiomboWoodlands," but struc- in MogfhmedesProvince in the south. turally and phenologically they are controlled by sea- Farther inland, this class includes. the highest sonal precipitation and flooding. Baikiaeaplurijuga' areas of the country on the Bi6iPlateau to the north- woodland isdonminantinmnanyareas, alternating with west of Huambo, extensive high areas in Huila Prov- grassland and mixed savannas containing Acacia ince, and smaller areas in Kuan do-ICubango Prov- siebemana,Diospyos mespiliformis,and sometimes Aca- ince. The coverage in Angola is 82,573 square cia eriolobaalong the rivers. In some higher areas, kilometers. Other occurrences are in Zambia, in the however, a woody commnunityof Combretumnimberbe, upper Zambezi and tributary areas of Northwestern D. mespiliformis,and Ficussycomnorus occur, although and Western provinces, including West Lunga Na- this is sometimes domiinated by Acaciaalbida (an ex- tional Park, totaling 86,420square kilometers. It also ample is along the upper Cunene River). Along drain- is an important class in Malawi, where it covers age lines in Kuando-Kubango, savanna communities 11,751square kilometers. occur, dominated by Acacia spp., along with islanid In Mozanbique, extensive areas occur on higher thickets of savanna species, sometimes dominated by land in Niassa Province. A few small high-altitude the palm BorassusathAiopum, on old termitaria. areas are present in NamnpulaProvince and on Planalto 164 EstimaintigWoody Bomass ill Siub-SaImmnAfrica do Mavia in Cabo DelgadoProvince. The area of this soilsenable sufficient moisture to be reservedthrough class in Mozambique is 76,039square kilometers,In the dry season to allow plant growth. It also includes Zimbabwe,the most significantareas are in the higher some areas of intensiveagriculture, such as tobacco parts of MatabelelandNorth, totaling 29,931square and sugarcanenear Lusaka. kilometers.In South Africa(22,237 square kilometers) The "Dry EvergreenForests" of the Zambian Pla- and Swaziland (2,687square kilometers),this class is teau now are limited in extent but include "Parnhiri represented by high-altitude forestedareas in south- Forest," which has two main canopy trees, Painmari eastern Transvaaland Swaziland,and at the northem excelsaand Syzygiwnguineense. Common understory end of the Drakensbergsin northern Transvaal. trees in this type of forestare Aidiamicrntha, Chryso- In the tropics, this class demonstrates a similar phe- phylluin rnegalismontanum,Olea capensis, Tabemaeinon- nology to that of Wet MiomboWoodland (Class 67), tanaangolensis, and Tecleanobilis. All of the "Dry Ever- but with slightlylower overallNDVI values.It exhibits green Forests" show signs of invasion by iniomnbo high levels from November through June, mostly woodland trees at their edges, suggestinga great eco- greater than 0.42,decreasing throughJuly and August logicalfragilityunderpresentclimaticconditions. Dis- to 0.25 in September. This behavior reflects the in- turbanceby anthropogeniccauses leads to formation creased effect of cooler temperatures at higher alti- of "ChipyaWoodland." Someareas in westem Zai- tudes in winter, followedby a very sharp increasein bia are protected reserves;for example,West Lunga productivity through November (figure 13-10).The NationalPark. subtropical areas in South Africa and Swaziland In Malawi,this classrepresents "MontaneRain For- demonstrate a similar seasonal pattern but with sig- est," which now is rare and occurs onlyon the wetter nificantly lower NDvxvalues. Those above 025 are eastern slopesof higher mountainsbetween 1,200and attained from Novemberthrough April,but declineto 2,500 meters. Mean annual rainfall usually exceeds 0.12in August and September (figure 13-10). 1,250millimeters, and anydryseasoneffects are coun- I Angola,the vegetation in theseareas is similar to tered by mists. The. forest is well structured, with that described as Wet MiomboWoodland (Class 67) canopy speciesreaching a height between 24 and 45 and EvergreenWoodland Mosaic (Class 71), but with meters.A mniddletree stratum, between 6 and 15me- slightly less overall productivity. This is caused ters,forms a denseclosed canopywith a poorlydevel- mostly by the effectof higher altitude on growth, but opea herb and grass layer. The rich flora includes in some areas by varying degrees of interference.The- Aningeria adolft-friedericii,Chrysophyllum gorungo- classincludes, for example,Pare Nacionalda Kisama sanum,Colagreenwayi, Diospyrosabyssinica,Myriant bus to the southeast of Luanda, parts of Parc Nacionalda holstii,Odcna hoistii, Olea capensis, Prunus africana, and Biknar in Huila Province, and high, less-accessible Syzygiumguineense. areas such as those on the west-fTcingSerra Upanda Apart from the general types of moontarneforest in and the Serra da Chela escarpment Malawi,some forest areas are dominated by a single In Zambia, this class is again miombowoodland, tree species.On the Nyika Plateau,pure stand forests with vegeta ion types similar to those of woodlands of muziperusprocera and Hageniaabyssinica exist. The described in Classes 67 and 71. Here, however, the J. proceraforest is formed on slightly drier slopes be- classalso includes parts of the "Dry EvergreenForest" tween 1,800and 2,900meters altitude and reaches 30 (Er Foundation 1987),in which moisture-retaining meters in height. Some evidence suggests that it is controlledby fire.The Hageniaforest has similar alti- Figure 13-10. NDVI Profiles,Evergreen Forest tudinaland precipitationcontrols and forms a canopy (Class 82) 8 to 15 meters tall on the forestmargin, but it is not fire tolerant. 0.6 On the Mulanje Massif, between 1,525and 2,135 meters altitude, forests of Mulanje cedar (Wid- 0.5- dringtoniacupressoides) exist, 25 to 40 meters high. The

0.4 - - .-/ forest reserves in Malawi are mainly reservations of 0.4/ existing areas of "Montane Rain Forest" or dosed- a0.3- canopywoodland on the lowlands-Locally important z - exotictimber plantations exist, mostly of pine. Some 0.2o of these areas are classifiedin this land cover class;

- 2 Swazaand -~i~ - -otherwise they are classified in Classes 67 and 71. -. l 82 WcsternLia In Mozambique,this class occurs mostly in Manica :2 Wester Zambia Provinceon the Zimbabweanborder and extensively Jan IFebN;r.Ap, any lun Jul AugScp Oct NovDec inNiassa Province(for example, near Lichinga).Afew SoutizenaAfrica 165 outliers exist at higher altitude near Nampula and on western Swaziland Highveld, extending across the the Planalto do Mavia in Cabo Delgado Province. The border into South Africa near Piet Retief. The planta- short dry season often is offset by mists, because the tions are domCinatedby pines, in particular Caribbean areas of forest all occurabove 1,200meters. imports such as Pinus elliottii,P. patula, and P. taeda, They range from well structured to poorly struc- which are mainly destined for South African pulp tured and are floristically diverse, including conifers mills. Some of the southern SwaziJand and South Af- as well as broad-leaved tree species.In the high-altitude rican plantations are of gum, especially Eucalyphts areas, where precipitation is greater, a well-structured granolisand E. saligna,of black wattle (Acaciamearnsii), forest can form with a well-developed, not dense can- or of poplar (Populusdeltoides). opy between 14 and 30 meters high. Emergents reach Blackwattle has been an important source of tannin, heights of 25 to 45 meters, with a typical height being but because demand has declined, some areas in Swa- 30 to 38 meters. A lower, dense, small-tree canopy ziland have degenerated into "Wattle Jungle" (Mil- occurs between 6 and 15 meters, and beneath the tree lington and others 1989).Eucalyptus plantations have strata is a shrub layer of3 to 6 meters and a sparse grass expanded, however, the wood being extensively used and fem herb layer. The main tree species are Ocotea for poles and mining timber. In Swaziland, the conif- spp., Podocarpusspp. (especially P. latifolius),Prunus erous plantation area has expanded steadily during africana,and Xymalosmonospora. the past three or four decades. Timber statistics for In many areas, the montane forests are nov, much 1982show that the ratio of planted to natural forest is shorter than they were, and commonly form canopies 45.5 to 1 (Millington and others 1989). Natural forest between 8 and 15 meters. This height reduction usu- consists mainly of Cussonia umbelifera, Podocarpus ally is accompanied by a significant influx of second- latifolius,Rawsonia lucida, and Xymalosmonospora, usu- ary deciduous species, which take on a low-tree-and- ally orly on sheltered slopes. shrubby habit. Large proportions of this land cover Woody biomass growing stock and sustainable class in Mozambique are reserved, thereby restricting yield are ample in most parts of this land cover class, accessibility. but many places do not have any exploitable fuel- En Zinbabwe, the montane vegetation is complex wood. In parts of Angola, Zimbabwe, Mozambique, and forest is rare for two reasons. First, the Zimbab- and South Africa, this class is in various reserves and wean Mountains are generally lower than elsewhere thus is generally inaccessible. In most of Swaziland, in the region, and consequently stunted ericaceous and over much of South Africa, the plantations are forests exist only in the Chimanimani Mountains. Sec- inaccessible for fuelwood exploitation, except for the ond, the wet, windward slopes of the "Zimbabwean" "Wattle Jungles" of Swaziland, which provide a valu- Mountains are in Mozambique, for example near In- able local wood resource.It Zambia, much ofthis class yanga National Park, and only the dry leeward slopes is in ecologicallymarginal situations (Erc Foundation occur in Zimbabwe. Consequently, much of this class 1987) anci any exploitation mnaylead to a degraded consists of otherwoodland forms (see Class 61) rather "Chipya Woodland." Generally,many of the montane than true montane forest. forest areas are at high altitudes and far from the Above the miombowoodland or on wetter sites at centers of population. similr altitudes, montane forests do occur. In these This class has an estimated growing stock of 1,877 forests, trees rarely exceed 15 meters, but a canopy million tonnes, with a sustainable yield of 156million more commonly forms between 9 and 13 meters. tonnes. It is about 4 percent of the woody biomass Below the canopy, a number of other smaller trees resource of southern Africa. exist, varying in height between 3.5 and 9 meters. The most common species are Agauria salicifolia,Aphloia Land Cover Class Tables inyrtiflora(theiformis), Apodytes dimidiata, Cussonia spi- cata,Diospyros whyteana, Dombeya enfthroleuca, Hagenia Tables 13-1 through 13-10, beginning on page 167, benguelensis,Pexmitis,Junmixrusprocera, Kiggelariaafiic- present summaries for each land cover class of the one,Myrica salicfQlia, Nuxia congesta, N floribunda,Olinia area, showing growing stock and sustainable yield for usambarensis,Philippi benguelensis,Pittosporum zri-- the southern African nations of Angola, Botswana, diforum, Podocarpuslatifplius, Prunus africana,Ptero- Lesotho, Malawi, Mozambique, Namibia, South Af- celastrusspp., Rapaneaspp., Trichocladusellipticus, Wid- rica, Swaziland, Zambia, and Zimbabwe. dringtonianodyifora, and Xymalos monospora.Parts of this land cover class in Zimbabwe are reserved. References In Swaziland and South Africa, the majority of this class exists in plantations, although there are a few Every efforthas been made to facilitate access to the natural forests. They are exemplified by those of the documents listed here. Some documents, however, 166 EsltinratingWoody Biom0ss in SblSa)mra,iAfrica lack fuli bibliographic information because it was Rutherford, M. C. 1978."Ka roo-Fynbos Biomass Along unavailable; also, some documents are of limited anElevationalGradientintheWestemCape.'"Bothalia circulation. 12(3):555-60. Scheepers,J. C. 1975."The Plant-Ecology of the Kroon- Acocks, J. P. H. 1953. "Veld Types of South Africa." stadandBethlehemAreasoftheHigh VeldAgricul- Memoirs of tire BotanicalSurvey of SoutlhAfrica-28: tural Region." Ph.D. diss., University of Pretoria, 1-192. South Africa. Acocks, J. P. H. 1975. "Veld Types of South Africa." Stomgaard, Peter. 1985. "BiomnassEstintation Equa- Memoirs of tile BotanicalSurvey of South1Africa 40: tions for MionmboWoodland, Zambia." Agroforestry 1-128. Systems 3(1):3-13. Chidumayo, E. N. 1987."Species Structure in Zambian Stomgaard, Peter. 1986."Early Secondary Successionin MiomiboWoodland." Journalof TropicalEcologly 3(2): Abandoned Shifting Cultivator's Plots in the Miombo 109-18. of South Central Africa." Biotropica18(2): 97-106. Christopher, A. J. 1982.Soutih Africa. London: Longman. Taylor, H. C. 1972. "Fynbos." Veldand Flora2:68-75. Coelho,H.V.P. 1967. 'ZonagemflorestalnoDistrictodo Taylor, H. C. 1978. "Capensis." Chapter 8 in M. J. A. Cuando Cubango." AgronomicasAigolana 26:3-27. Werger, ed., Biogeographyand Ecologyof Southern Edwards, I. D. 1982. "A Quantitative Description of an Africa.The Hague: Junk. Area of Savannah Woodland at Nichira Mountain van der Merwe, J. H. 1983.National Atlas of South West Conservation Area, near Blantyre."Forestry Research Africa.University of Stelienbosch, South Africa: In- Institute of Malawi, Lilongwe.' stitute for Cartographic Analysis. ETc(Education andTrainingConsultants) Foundation. Weare, P. R., and A. Yalala. 1971. "Provisional Vege- 1987.Wood Energy Development: Bioinass Assessment, tation Map of Botswana."Botsrwana Notes and Re- a Sktdy of the SADccRegion. Leusden, Netherlands. cords3. Fanshawe, D. B. 1969. mTheVegetation of Zambia." Werger, N. J. A. 1978. Biogeographyand Ecology of ForestResearch Butletin 7. SouthernAfrica. The Hague:Junk. Millington, Andrew C., John R. G. Townshend, Pam Werger, M. J. A., and B.J. Coetzee. 1978. "Me Sudano- A. Kennedy, Richard Saull, Steven D. Prince, and Zambezian Region." Chapter 10 in M. J. A. Werger, Robert Madams. 1989. BiomassAssessment. Woody ed., Biogeographyand Ecology of Southernfirica. The Biomassin the SADCCRegion. London: Earthscan. Hague: Junk. moll, E. J., and L BossL 1984. "Assessment of the White, F. 1983. "The Vegetation of Africa." Natural Extent of the Natural Vegetation 3f the FynbosBiome ResourcesResearch Series 20. Paris: UNESCO/lArPATI in South Africa." South African Journalof Science80 uNso (United Nations Educational, Scientific and (August):355-58. Cultural Organization/Association pour l'Etude MolLE.J., and Id. L. Jarman. 1984. "Clarification of the Taxonomique de la Flore de l'Afrique Tropi- Term Fynbos.n South African Journal of Science 80 cale/United Nations Sudano-Sahelian Office). (August):351-52. White, F., and E. J. MolL 1978. "The Indian Ocean Rutherford, M. C. 1972. "Notes on the Flora and Veg- Coastal Belt" Chapter 13 in M1. A. Werger, ed., etation of the Omuverume Plateau, Mountain Biogeographyand Ecology of Southern Africa. The Waterberg, South West Africa." Dinteria83-55. Hague: Junk SooitheniAfrIca 167

Table 13-1. Land Cover Classes-Angola (Southern Africa Region)

- ______Aren- Growin stock SusInilmableyield Tiousasnd. Tiwusandtomines Landcouer clanss km2 Percelnt lionnes Pement per ear Pcrceui 0 20,446 1 68 0.00 0.00 0.00 0.00 II 22,922 1.89 5,203.29 0.09 229.22 0.19 14 105 0.01 23.84 0.00 1.05 0.00 1 ' 23,027 1.90 5,227.13 0.09 230.27 0.19 24 15,967 1.32 959.95 U.02 159.67 0,13 25 5,586 0.46 1,843.38 0.03 55.86 0.05 2 21,553 1.78 2,833.33 0.05 215.53 -0.18 33 33,725 2.78 33,725.00 0.60 1,68625 1.40 35 2,002 0.16 1,121.12 0.02 100.10 0.08 3 35,727 2.94 34,846.12 0.62 1,786.35 1.48 41 1,107 0.09 1,538.73 0.03 23.25 0.02 42 5,322 0.44 9,851.02 0.17 111.76 0.09 43 71,244 5.87 120,544.85 2.13 1,496.12 1.24 4 77,673 6.40 131,934.60 2.34 1,631.13 1.35 51 25,768 2.12 57,462.64 1.02 1,623.38 1.35 5 25,768 2.12 57,462.64 1.02 1,623.38 1.35 61 127,944 10.54 376,155.36 6.66 5,629.54 4.67 66 450,070 37.09 2,503,739.41 44.32 40,056.23 33.22 67 150,234 12.38- 1,787,784.60 31.65 19,981.12 16.57 6 728,248 60.01 4,667,679.37 82.63 65,666.89 54.46 71 96,222 7.93 49,361.89 0.87 1,828.22 1.52 72 99,172 8.17 167,005.65 2.96 1,884.27 1.56 7 195,394 -16.10 216,367.54 3.83 3,712.49 3.08 82 82,573 6.80 495,438.00 8.77 41,121.35 34.10 85 2,002 0.16 25,581.56 0.45 2,962.96 2A6 87 1,107 0.09 11,61132 0.21 1,638.36 1.36 8 85,682 7.06 532,630.88 9.43 45,722.67 37.92 Total 1,213,518 100.00 5,64B,981.61 100.00 120,588.71 100.00 (Percentage of region) (20.45) (30.24) (26.90) Note: In the followingtables, details may not add to totalsbecause of rounding. Source:Authors' calculations from data bases derived fron land coverclassification and table4-1. 168 EslimatingWoody Biomass in Sub-Salmran Afric

Table 13-2. Land Cover Classes-Botswana (Southeem Africa Region) Are Growinjgstock S-slainablcyicld Thousatnd Titousandtonses Land cocr class km2 Parcenl lannes Percenl peryear Percent 0 29,457 5.01 0.00 0,00 0,00 0.00 11 53,380 9.07 12,117.26 2.61 533.80 3.13 14 105 0.02 23.84 0.01 1.05 0.01 1 53,485 9.09 12,141.10 2.62 534.85 3.14 24 240,607 40.90 14,917.63 3.22 2,406.07 14.10 2 240,607 40.90 14,917.63 3.22 2,406.07 14.30 33 316 0.05 316.00 0.07 15.80 0.09 34 52,643 8.95 52643.00 11.35 2,632.15 15.43 35 -0,547 10.29 33,906.32 7.31 3,027.35 17.75 3 113,506 19.30 86,5.32 18.74 5,675.30 33.27 42 158 0.03 292.46 0.06 3.32 0.02 43 10,117 1.72 17,117.96 3.69 212.46 1.25 4 10,275 1.75 17,410.42 3.76 215.78 1.26 51 97,012 16A9 216,336.76 46.66 6,111.76 35.83 5 97,012 16A9 216,336.76 46.66 6,111.76 35.83 61 24,767 4.21 72,814.98 15.71 1,089.75 6.39 66 1,528 0.26 8,500.26 11.3 135.99 0.80 6 26,295 4.47 81,315.24 17.54 1,225.74 7.19 72 16,441 2.79 27,686.64 5.97 312.38 1.83 7 16,441 2.79 27,686.64 5.97 312.38 1.83 82 1,159 0.20 6,954.00 1.50 577.18 3.38 8 1,159 0.20 6,954.00 1.50 577.18 338 Total 588,237 100.00 463,627.12 100.00 17,059.05 100.00 (Percentage of region) (9.91) (2.48) (3.80) Source: Authors' Calcu.dtionsfrom data bases derived from land cover classificationand table 41.

Table 13-3. Land Cover Classes -Lesotho (Southern Africa Region) Area Growinigstock Sustainableyield Tihousand Thousaondtonnes Land co ecL'ss km2 Percent tonnes Percent peryear Percenf 11 25,136 73.27 5,705.87 56.83 251.36 68.78 14 7,535 21.96 1,710.45 17.04 75.35 20.62 1 32,671 95.23 7,416.32 73.87 326.71 89.40 24 369 1.08 22.88 0.23 3.69 1.01 2 369 1.08 22.88 0.23 3.69 1.01 43 896 2.61 1,516.03 15.10 18.82 5.15 4 896 2.61 1,516.03 15.10 18.82 5.15 61 369 1.08 1,084.86 10.81 1624 4.44 6 369 1.08 1,084.86 10.81 16.24 4.44 Total 34,305 100.00 10,040.09 . 100.00 365.45 100.00 (Percentage of region) (058) (0.05) (0.08) Source:AuthorS calculatons from data bases derived fron land cover dassification and 'able4-1. SouwhermAfrica 169

Table 13-4. Land Cover Caasses-Malawi (Southern Africa Region) Area G QWti,slock -Sustainnbleyield -Tousand Thousandlonnes Landcover class km Percent Lonns Percent peryear PeceCCt 11 316 0.24 71.73 0.01 3.16 0.03 - 1 : 316 0.24 71.73 0.01 3.16 0.03 24 53 0.04 3.29 0.00 0.53 0.00 25 158 0.12 52.14 0.01 1.58 0.01 2 211 0.16 55.43 0.01 2.11 0.02 33 2,477 1.92 2,477.00 0.50 123.85 1.02 3 2,477 1.92 2,477.00 0.50 123.85 1.02 41 158 0.12 219.62 0.04 3.32 0.03 43 32,408 25.07 54,834.34 11.09 680.57 5.58 4 32,566 25.19 55,053.96 11.13 683.89 5.61 51 474 0.37 1,057.02 0.21 29.86 0.24 5 474 0.37 1,057.02 0.21 29.86 0.24 61 4,005 3.10 11,774.70 2.38 176.22 1.45 65 53 0.04 141.51 0.03 2.54 0.02 66 46,425 35.92 258,262.27 52.21 4,131.82 33.90 67 7,694 5.95 91,558.60 18.51 1,023.30 8.40 6 58,177 45.01 361,737.08 73.13 5,333.89 43.76 71 2,635 2.04 1,351.76 0.27 50.06 OAI 72 263 0.20 442.89 0.09 5.00 0.04 .7 2,898 224 1,794.65 0.36 55.06 0.45 82 11,751 9.09 70,506.00 14.25 5,852.00 48.01 83 211 0.16 1,873.26 0.38 105.08 0.86 8 11,962 9.25 72,379.26 14.63 5,957.08 48.87 Lakes 20,182 15.61 0.00 0.00 0.00 0.00 Total 129,263 100.00 494,626.12 100.00 12,188.90 100.00 (Percentage of region) (2.18) (2.65) (2.72) Source Authos' cakubtions fromdatW bases derived from land cover dassification and table4-1.

-. j4 170 EsimnalingWoody Bionuss itnSb-Snl:arani Africa

T-ible 13-5. Land Cover Classe--Mozambique (Southern Africa Region) Area Growingslack Sutstainableyield Thnousand Tlaousaizdfauines Lnndcover class km - Percnt lanncs Percent peryear Percent 11 6,271 0.82 1,423.52 0.04 62.71 0.07 .14 474 0.06 107.60 0.00 4.74 0.01 1 6,745 0.88 1,531.12 0.04 67.45 0.07 24 16,388 2.14 1,016.06 0.03 163.88 0.18 2 16,8B 2.14 1,016.06 0.03 163.88 0.18 33 2,529 0.33 2,529.00 0.06 126.45 0.14 35 4,743 0.62 2,656.08 0.07 237.15 0.26 3 7,272 0.95 5,185.08 0.13 363.60 0.40 41 53 0.01 73.67 0.00 1.11 0.00 42 316 0.04 584.92 0.01 6.64 0.01 43 75,03B 9.78 126,96430- 3.17 1,575.80 1.75 4 75,047 9.83 127,622.89 3.18 1,583.55 1.76 51 31,143 4.06 69,448.89 1.74 1,962.01 2.18 5 31,143 4.06 69,448.89 1.74 1,962.01 2.18 61 26,295 3.43 77,30730 1.93 1,156.98 1.28 66 360,646 47.02 2,006,273.70 50.15 32,097.49 35.61 67 102,861 13.41 1,224,045.90 30.60 13,680.51 15.18 6 489,802 63.86 3,307,626.90 82.68 46,934.99 52.08 71 59,071 7.70 30,303.42 0.76 1,122.35 1.25 72 475 0.06 79822 0.02 9.01 0.01 7 59,545 7.76 31,101.64 0.78 1,131.36 1.26 82 76,039 9.91 456,234.00 11.40 37,867.42 42.M 83 105 0.01 932.19 0.02 52.29 0.06 8 76,144 9.93 457,166.19 11.43 37,919.71 42.07 Lakes 4,584 0.60 0.00 0.00 0.00 0.00 Total 767,030 100.00 4,000,698.75 100.00 90,126.54 100.00 (Percentage of region) (12.93) (21.42) (20.10) Source Authors'calcubtions from data bases derived fromland coverclassification and table4-1. SouthernAfrica 171

Table 13-6. Land Cover Classes-Namibia (Southem Afnca Region) Area GCwingslock Sustainableyield Tliousand riouisandtonnes Lantdcover clanss ku Percenti tonnes Percent peryear Percent 0 221,478 27.13 0.00 0.00 0.00 0.00 11 15,282 1.87 3,469.01 0.41 152.82 0.64 - 14 211 0.03 47.90 0.01 2.11 0.01 -1 .15,493 1.90 3,516.91 0.42 154.93 0.65 24 161,458 19.78 10,010.40 1.19 1,614.58 6.74 25 211 0.03 69.63 0.01 2.11 0.01 2 161,669 19.81 10,080.03 1.20 1,616.69 6.75

33 . 7,493 0.92 7,483.00 0.89 374.15 1.56 34 63,603 7.79 63,603.00 7.59 3,180.15 13 28 35 50,061 6.13 28,034.16 3.34 2,503.05 10.45 3 121,147 14.84 99,120.16 11.82 6,057.35 25.30

41 2,213 0.27 3,076.07 0.37 . 46.47 0.19 42 2,108 0.26 3,901.91 0.47 44.27 0.18 43 13,964 1.71 23,627.09 2.82 293.24 1.22 4 18,285 2.24 30,605.07 3.66 383.99 1.60 51 166,464 20.39 371,214.72 4428 10,487.23 43.79 5 166,464 2039 371,214.72 44.28 10,487.23 43.79 61 99,278 12.16 291,87732 34.82 4,368 18.24 66 1,581 0.19 8,795.10 1.05 140.71 0.59 6 100,859 12.36 300,672.42 35.87 4,508.94 18.83 72 9,801 1.20 16,504.88 1.97 186.22 0.78 7 9,801 1.20 16,504.88 1.97 186.22 0.78

82 . 1,107 0.14 6,642.00 0.79 55129 2.30 8 1,107 0.14 6,642.00 0.79 55129 2.30

Total . 816,303 100.00 838,356.19 100.00 23,946.63 100.00 (Percentage of region) (13.76) (4.49) (534) SourwAuthors' calculations rom data basesderived frxn landcowver dassification and table4-1.

.*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - - .- 4-. -7.r:'>:. . - .4 - . -. , r 172 EstimatingWoody Biomass in Sub-SalarmnAfrica

Table 13-7. Land Cover Classes-South Africa (Southern Africa Region) ._ Arcom - -. GCrouii!stotc Sustainableyield T-houisand. -Touisatnd tonnes Landcover class km2 Percent lonnes Percent peryear Percc - 0 79,148 6.48 0.00 0.00 0.00 0.00 11 214,364 17.56 48,660.63 2.92 -Z143.64 3.98 14 6,587 0.45 1,49525 0.09 65.87 0.12 1 - - 220,951 18.10 50,155.88 3.01 2,209.51 4.10 24 171,365 14.04 10,624.63 0.64 1,713.65 3.18 25 1,370 0.11 452.10 0.03 13.70 0.03 2 172,735 14.15 11,076.73 0.67 1,727.35 3.21 31 4,005 0.33 3,424.28 0.21 200.25 0.37 32 24,978 2.05 -11,240.10 0.68 1,248.90 2.32 33 70,032 5.74 70,032.00 4.21 3,501.60 6.50 34 129,367 10.60 129,367.00 7.77 6,468.35 12.01 35 123,781 -10.14 69,317.36 4.16 6,189.05 11.49 3 - 352,163 28.86 283,380.74 17.03 17,608.15 32.70 42 17,021 1.39 31,505.87 1.89 357.44 0.66 43 111,767 9.15 189,109.76 11.36 2,347.11 4.36 4 128,788 10.54 220,615.63 13.25 2,704-55 5.02 51 142,277 11.65 317,277.71 19.06 8,963.45 16.64 5 142,277 11.65 317,277.71 19.06 8,963.45 16.64 61 : 19,023 1.56 55,927.62 3.36 837.01 1.55 66 54,065 4.43 300,763.59 18.07 4,811.78 8.94 67 23,344 1.91 -277,793.60 16.69 3,104.75 5.77 6 96,432 7.90 634,484.81 38.12 8,753.54 16.26 71 474 0.04 243.16 0.01 9.01 0.02 72 -5,270 0.43 8,874.68 0.53 100.13 0.19 7 5,744 0.47 -9,117.84 0.55 109.14 0.21 82 - 22237 1.82 133,422.00 8.02 11,074.03 20.56 87 474 0.04 4,971.79 0.30 701.52 1.30 8 22,711 1.86 138,393.13 8.31 11,775.55 21.86 Total 1,220,949 100.00 1,664,503.13 100.00 53,851.24 100.00 (Percentage of region) (2058) (8.91) (12.01) ScurceAuthors' calculations from data basesderived fromland coverclassification and table4-1. SoUI1hen1Africa 173

Table 13-8. Land Cover Classes-Swaziland (Southem Africa Region) Area Crowingstock Suslainabieyield *-Thousand 7Thousand.lonncs Landcover class kn2 Percent tonnies Percrnt peryear Percenit 24 474 2.64 29.39 0.05 4.74 0.23 2 474 2.64 29.39 0.05 4.74 0.23 * 35 105 0.58 58.80 0.09 5.25 0.26 3 105 0.58 58.80 0.09 5.25 0.26 3 43 7,58 422 12,838.90 20.25 159.35 7.2 4 7,588 42.23 12,838.90 20.25 159.35 7.82 61 2,319 12.91 6,817.86 10.75 102.D4 5.01 66 4,479 24.93 24,916.68 39.29 398.63 1956 67 211 1.17 2,510.90 3.96 28.06 1.38 6 7,009 39.01 34,245.44 54.01 528.73 25.95 71 53 0.29 27.19 0.04 1.01 0.05 72 53 0.29 89.25 0.14 1.01 0.05 7 106 0.59 116.44 0.18 2.01 0.01 82 2,687 14.95 16,122.00 25.42 1,338.13 65.65 8 2,687 14.95 16,122.00 25.42 1,338.13 65.65 Total 17,969 100.00 63,410.96 100.00 2,038.21 100.00 (Percentage of region) (0.30) (0.34) (0.45) So2J Authors'calculations from data basesderived fromland cover dassification and table4-1.

Table 13-9. Land Cover Classes--Zambia (So2them Africa Region) Araa Growingstock Sustainableyield -whousand Tousand tonnes Land coverclass bn2 Percent tonnes Pecnt peryear Percent 11 1,686 0.23 382.72 0.01 16.86 0.02 1 1,686 0.23 382.72 0.01 16.86 0.02 24 25,294 338 1,568.23 0.04 252.94 0.27 25 2,1O8 0.28 695.64 0.02 21.08 0.02 2 27,402 3.67 2263.87 0.06 274.02 0.29 33 843 0.11 843100 0.02 42.15 0.05 3 843 0.11 843.00 0.02 42.15 0.05 42 738 0.10 1,366.04 0.03 15.50 o.m 43 55,067 7.37 93,173.36 2.30 1,156.41 1.24 4 55,805 7.47 94,539.40 2.34 1,171.91 126 51 9,116 11222 20,328.6B 050 574.31 0.62 5 9,116 1.22 20,328.68 0.50 574.31 0.62 61 72,561 9.71 213,329.34 5.27 3,192.68 3.42 66 344,891 46.15 1,918,628.63 47.42 30,695.30 32.88 67 102,967 13.78 1,225,307.30 30.28 13,694.61 14.67 6 520,419 69.64 3,357,265.27 82.97 47,582.59 50.97 71 6,060 0.81 3,108.7B 0.08 115.14 0.12 72 29,193 3.91 49,161.01 1.21 554.67 0.59 7 35,253 4.72 52,269.79 1.29 669.81 0.71 82 86,420 11.56 518,520.00 12.81 43,37.16 46.09 8 86,420 11.56 518,520.00 12.81 43,037.16 46.09 Lakes 10,381 1.39 0.00 0.00 0.00 0.00 Total 747,325 100.00 4,046,412.74 100.00 93,36iŽ,0 100.00 (Perettage of region) (1259)- (21.66) (20.2) Source.Authorscakulations from databases derivedfrom land cover classification and table4-1

. . . .f . X ' - - -- -' X- . ~ ; 0 - 174 EstimatingWoody Biomass in Sub-SulhamnAfrica

Table 13-10. Land Cover Classes-Zimbabwe (Southern Africa Region) Area Growingstock Stustainableyield 7housand -7tousan1d tonnes Landcover class -km,, 2 Percent tonnes Percent peryear Pcrcent 11 1,212 0.30 275.12 0.02 12.12 0.03 14 422 0.11 95.79 0.01 - 4.22 0.01 1 1,634 0.41 370.91 0.03 16.34 0.04 24 25,610 6.42 1,587.82 0.11 256.10 0.74 2 25,610 6.42 1,587.82 0.11 256.10 0.74 35 3,425 0.86 1,918.00 0.13 171.25 0.49 3 3,425 0.86 1,918.00 0.13 171.25 0.49 42 474 0.12 877.37 0.06 9.95 0.03 43 63,498 15.92 107,438.62 7A3 1,333A6 3.83 4 63,972 16.04 108,315.99 7.49 1,343A1 3.86 51 47,637 11.94 106,230.51 7.34 3,001.13 8.62 5 -47,637 11.94 106,230.51 7.34 3,001.13 8.62 61 115,455 28.94 339,437.70 23.46 5,080.02 14.59 66 78,252 19.62 435,315.88 30.09 6,964.43 20.00 67 22,606 5.67 269,011.40 1859 3,006.60 8.64 6 216,313 54.23 1,043,764.98 72.14 15,051.05 43.23 71 1,265 0.32 648.95 0.04 24.04 0.07 72 2,582 0.65 4,348.09 0.30 49.06 0.14 7 3,847 0.96 4,997.D4 0.34 73.10 0.21 82 29,931 7.50 179,586.00 12.41 -14,905.64 42.81 8 29,931 7.50 179,586.00 12.41 14,905.64 42.81 Lakes 6,534 1.64 0.00 0.00 0.00 0.00 Total 39B,903 100.00 1,446,771.25 100.00 34,818.01 100.00 (Percentage of region) (6.72) (7.75) (7.77) Source Authors calculaionsfrom data basesderived from land covercassification and table4-]. Glossary

- - acheb LocalWest African term forherbaceous vegetation growth following rainfall in arid areas. - alfisol(s) A relatively productive, and therefore agriculturally important, type of soil com- monly occurring in West, East, and southern Africa;characterized by downward movement of water, day minerals, and cations. anthropogenic Vegetation that has formed or is controlled mainly by human activity (for example, anthropogenic savannas and anthropogenic grasslands). See also DERavD SAVANNA. arborescent Having a treelike form. Archaean complex .Precambrian basement rocks; some occur in various parts of Africa. See also PRECAMBRIAN.

basement complex See ARCHAN COMPLEX. base-rich Soils that have high cation content (for example, caldum, magnesium, potassium) and are, therefore, usually highly productive. boliands The region in central Sierra Leone where the landscape is domlinated by bolis. bolis SeasonalLyflooded, low-lying areas in central Sierra Leone. The edaphic climax vegetation of such areas is grassland and swamp forest, but they often are cleared for rice cultivation. They are somewhat similar to the dambosof East and central Africa bush fallowing A farming system common in humid tropical Africa in which forest or woodland is cut, dried, and burned, then cultivated for one to four years and allowed to revert to a fallow of secondary woody vegetation. See also CHmvENs

calcrete A sedimentary pedogenic deposit composed of rock fragments cemented together by calcium carbonate. Cape Domain A regional center of endemism covering the southwestern and southern part of Cape Province, South Africa (after White 1983). Capensis Realm The geographic area recognized as the Fynbos Biome, equivalent to Cape Floristic Region or Cape Floral Kingdom (after Werger 1978). chipya A local Zambian name for a variety of woody vegetation regrowth. chitmene A type of bush-fallowing farming system practiced by the Bemba in Zambia. See also susH FALLowING. cirrus cloud A high-level, white, wispy cloud occurring at an altitude between 5,000 and 13,700: meters. commercial wood Wood useful in construction or manufacturing, which gives it a value such that it is not used as firewood. Cretaceous Geologic period extending from 65 million to 135million years ago.

175 176 EstimnaliiigWoody Biomnssin Slib-ShllaraiAfrica

dambo A southem African term for a seasonally waterlogged streamless hollow with vegetation differing from the surrounding woodland or savanna, commonly occurring in East, central, and southem Africa. dbh- Diameter at breast height: a measurement of tree girth at 1.3 meters above the ground. derived savanna Savanna vegetation formed and sustained by human activity, resulting from dis- turbance of a different type of vegetation, usually forest. See also ANTHROPONDC.

edaphic Vegetation that is adapted to, and controlled by, the soil and groundwater condi- tions of a site; for example, edaphic grasslands. elfin thicket Thickets of stunted and gnarled woody vegetation found at high altitudes. ephemeral Vegetation which grows only occasionally in response to favorable conditions, usually wet. Common in arid and semiarid areas. ephemerals Ephemeral plant species. erg An arid (desert) landscape consisting of extensive sand cover. ericoid A descriptive tenn for plants having a shrubby growth habit, like heathers.

fire resistant Plants with thick bark or other adaptations which enable them often to survive fire. fire tolerant Plants with a limited tolerance to fire, better able to survive fire than nontolerant plants, but less able to survive fire than fire-resistant species. -Jnbos A Mediterranean evergreen sclerophyllous shrubland occurring in South Africa.

gallery forest A dense growth of tropical forest that follows the course of a river. -i-.z A local term for the flush of grass-dominated vegetation that grows in the Libyan Desert following rainfall events. ground resolution element The smallest area of the Earth's surface that a sensor can resolve. For each ground resolution element, one measurement of reflection per channel occurs on a sensor. growing stock Air-dried, above-ground woody biomass, expressed in tonnes per hectare. Guineo-Congolian Domain A regional center of endemism found as a broad band north and south of the equator from the Atlantic, through the Zaire Basin, to the western slopes of the dorsaledu Kivu (after White 1983).

halophyte A plant that is adapted to and favors growth in soils with a high content of soluble salt. Hammer-Aitoff Conic Equal Area Projection The map projection used in the construction of AVHRRNDV data. hardpan(s) A subsurface soil horizon that is often hard and rocklike. In the humid tropics, hardpan often forms by precipitation of iron and aluminum, which then harden to form a ferricrete (laterite). Hardpans usually form impermeable horizons in the soiL hanattan A dust-laden wind blowing off the Sahara from December to February. high forest Closed-canopy climax forest

illite A clay mineral derived from the weathering of mnicasand feldspars under alkaline conditions. isenga Sand patches on the Zambian Plateau. They lead to the growth of a distinct form of miombowoodland. iligi thicket AnEast African vegetation type containing many deciduous woody species which form a dense, intertangled thicket.

-KalahariSands Areas of Quatemary aeoLhansands from southem Africa northward into southern Zaire. kaolinite (kaolinitic) A clay mineral produced by the weathering of feldspar-rich rocks under add conditions,particularly common in humidl tropical soils. Classarry177

Karroo Domain Ihe area of summer rainfall east of the Westem Cape Domain and south of the Namaland Domain (after Werger 1978). kaukauwld A veld grasslandtype occurring on the Namnibia-Botswanaborder (Kaokoland). little dry season A.period of approximately 4 to 6 weeks, usually in August, during the wet season in West Africa when rainfall amounts decline markedly. The phenomenon is related to the northward movement of the Intertropical Convergence Zone (rrcz) and is restricted to the southerunost parts of th West African coast. macchia A term used in South Africa to describe heathlands and evergreen scierophyllous shrubland. mguba A local East African name for a VImRsOL miombo An open woodland land cover occurring in southern Africa. mnistbelt An area characterized byoULTPREcIPITAMTON. montmorillonite A clay mineral derived from the weathering of basic rocks. Montmorillonite-type clay minerals absorb moisture and swell during wet periods and contract during dryperiods. munga Open, parklike savanna woodland occurring in Zambia.

Namaland Domain A region of southem Africa covering the narrow escarpment belt inland of the Namib, broadening southward to include the southern Kalahari Plateau (after Werger 1978). Namib Domain A region of southern Africa comprising the arid coastal strip of Namibia between the Atlantic and the escarpment (after Werger 1978). occult precipitation Precipitation that occurs directy on vegetation in the form of condensation. It commonly occurs when humid onshore winds are forced to rise up high escarp- mmentsalong the coast. piosphere An area of degraded soil and vegetation around a waterhole or wells, occurrng in arid and semiarid areas. Precambrian The entire span of geological time before the start of the Cambrian Period at approximately 600 million years before the present proteoid A term applied to plants thathave leaveswhich are thickened, as in the genusProtea. qoz Stabilized wind-blown sands of Quatenary age in Sudan. Quatemary The current geological period, which began approximately 1.8 nillion to 2 million years before the present. raster A means of representing spatial data in the form of a grid. reg An and (desert) landscape consisting of extensive tracts of gravel. restoid Having a low, cushionlike form similar to that of the southem African genus Restio. sclerophyllous A term describing evergreen shrubs and trees thathave adapted to lengthy seasonal droughts by prolucing tough, leathery leaves. senescence Ripening and/or dieback of vegetation seral succession Sequential development of a plant comnmunityor communities over time. shalahaila - A term used in Lesotho to describe shrub woodland growing on overgrazed, degraded pasture. hiftingcultivation See isH FALLowncG. stem volume Volume of main woody stem derived from height and diameter measurements, expressed in cubic meters. st2r A stacked volume of wood, expressed in cubic mete! subcanopy The layer or layers of vegetation beneath the canopy 178 EstimatiingWoody Biorniss iin SUb-SalIarmt Africa succulent A plant with thick, fleshyleaves or stems that retain large amounts of moisture; common in arid areas. suffrutex An understory shrub. sustainableyield : Meanannual increment of air-dried,above-ground woody growth, expressedin tonnesper hectareper year. swvartveld A gently undulating landscape in Cape Province,South Africa,extensively culti- vated for wheat.

Tertiary Geologic period extenidingbetween 2 million and 65 million years before the present. thionicfluvisols Alluvialsoils, occurring mainly in estuaries, in which subsoil sulfuricacid builds up when the soils are dried. tonne Metricton; 1,000kilograms or 2,20462avoirdupois pounds. veld (1) A southem African term describingalmost treeless grassland. (2) A southem Africanterm used to define a region regardlessof land cover (for example,the Highveld of Swaziland). vertisol A blacksoil commonly found in semiaridareas which,because of its high montmo- rillonitecontani, swells during the wet season and shrinks and cracks open in the dry season. Oftendescribed as having 'cracking clays." vloere A localAfrikaans name for brackish,low-lying areas in the Karroo. wadi A valley in a desert that is wet only after heavy rain and will briefly support vegetation. wattlejungle A dense growth of previouslywell-managed, but now abandoned, plantations of Aca&amearnsii in Swaziland. WesternCape Domain A region of southern Africaincluding the coastalstrip and escarpmentmountains in SouthAfrica south of the Namib (afterWerger 1978). Wild Coast A localname for a remotestretch of the Transkeicoast between East London and Port Alfred. Woing Dega Localname given to the Ethiopianhighlands that experiencea temperateclimate. woodfuels Fuelwoodand charcoal. woodybiomass Ligneousplant material. Zambezi teak Name used by forestersfor the importanttimber tree BaikiaeAplurijuga in southern Africa. ZambezianDomain A region extending from the Atlantic to the Indian Ocean including Zambia, Malawi,and Zimbabwe,as welias largeparts of Angola,Tanzania, and Mozam- bique. Zone de l'igname An agriculturalzone extendingacross the centralC6te d'Ivoire. Index of BotanicalNames

Acacia,30,31,37,40,54-58,64,65,86-94,96-98, 105- Albizia, 124,130,148, 150, 159,161; adiantlifolia, 129, 07,109,120-24,126,127,138-41,144-50,152, 153, 157,160,162;amiaam, 91; anthelmintica;145, 150; 155,163; abyssinica,86, 96;;albida,57,58,92,107, antunesiana,156; gummifera, 128,160; sericoceplula, 124,126,136,148, 156,163; ainythetophylla,88, 91; 94; zygia,76,124, 128 rambica,87;asak, 88, 91;astringens, 92, 94; brevispica, Allanblackiastuhlimannii, 130 125;bussei, 90, 91; campylacantha, 123, 126; circum- Aloe,93,124; arborescens,147; bainesii, 157; dichotoma, nmrginata,123; cyanophyl a, 144; cyclops,142,144; 141, 145;eminens, 93; ferox, 138 dudgeonii,95,96; ehrenbergiana, 87; etrenbergiana Amblygonocarpusandongensis,152 (flava),55; erioloba,136-38,141,145,146,151,153, Ancistrophyliumsecundiflorum,74 163; etbaica,86, 91, 93;flava, 87;fleckii, 138; Andropogon,58, 66,67,69,106,124,125, 129,130,137; galpinii, 163; gerrardii, 120, 122, 124,126; gayanus,30,56-58; pseudopricus,57; schtirensis,105 glaucophylla(circumiarginata), 86; gourmuensis,95, Androstachysjohnsonii,140 96;haematoxylon, 145; hebeclada, 137,138,146,150; Aningeria,74,126,130; ado45iedericii,111, 129, 130, hebecladoides,123, 126;hererocusis, 150; hockii, 122; 164;altissima, 130 horrida,90, 119;karroo, 138, 147,154; laeta,55, 87, Annonasenegalensis, 106,109 92; leuderitzii,138; mearnsii,165; melanoxylon,144; Anogeissus,94,95,98; leiocarpus,57,94,95; schimpeni, melliffra,56,86,88-91,94,120,122,138,141,144; 67,68,92 meiffrn ss. detinens,137,141,145,146; montis-usti, Anthephora:argentea, 138; pubescens,138 145; nigrescens,147-50,161; nilotica,55,88,90,92, Anthonothafragrans,72 94,120, 122,147; niloticass kraussiana,140; nubia, Anthospermumaethiopicum, 144 87,89; reficiens,90,119,120,141,144,145,150; Anthosiemasenegalense, 75 reficiensss. misera,121,122; robynsiana,145; satigna, Antianistoxicaria, 75,128 142; senegal,55,56,87-89,91,92,97,119,120,126; Antidesmavenosum, 90,95, 96 seyal,55,56,86,88--94,97,106,119,122,126; seyal Aphioia rnyrtiflora(theiformis), 165 ss. multijuga,123, 126;seyal ss. subalata,94,120; Apodytes,86; dimidiata,98-100,130,147,158,165; sieberana,88, 91,123, 126,163; thomasii, 90; dimidiatavar. acutifolia,93 tomentosa,92, 94; toriilis,55,86-88,90-93,97,119, Aristida,120,122,137,138; adscensionis,55,119; 122,138; tortilis ss. raddiana,53,55,56,92; tortilis congesta,138; longiflora, 53; mutabilis,55,56, 119; ss. spirocarpa,120; venosa,88,91; zantkopholoea, 163; pungens,53; sieberana,55; stipoides, 55,56; xiphocarpa,86; xiphocarpa(abyssinica), 98 vanderysiii,105 Acalyphafruticosa,125 Arundinariaalpina, 99,121, 129 Acokanthera,93, 123,124; schimperi,93 Asparaguscapensis, 143 Adansoniadigitata, 57,65.66,90,121-23,148,150,156 Avicennia,77,85,129; africana,77; germinans,77 Adenolobuspechuelii,145 Afzelia,66-67; africana,58, 67,68,74,128; quanzensis, Baikie, 149,152,153,163; insignis(eminii), 130; 90,129,160 plurijuga,152,153,163 Agauriasalicifolia, 96, 165 Balanites,q5,97,120; aegyptiaca,53,55,57,87,92,95; Agrostis, 123,128,129; sclerophylla,87 maughamii,157; orbicularis, 90; racemosa,87; Aidiamiraniha, 108,164 wilsoniana,129

179 180 Eslirt7alingWoody Bionassin SSb-Salnamin Africn

Baphia:burttif, 123;inassaiensis, 123, 155, 156, 161; Catophractesalexanidri,141,144 -massaiensisss. obovata,153 Ceiba,57; pentandra, 75, 76, 128 Barbeyaolcoides, 93 Ceitis,74, 130, 157, 159; africana, 138, 147, 154; Bauldinia,160; nacranthat,137,146, 150;taitensis, 91 brownnii,128; integrifolia, 107; rnildbraedii, 75, 130; Berzelia:intermedia, 158; larniginosa,.144 zenkeri, 109, 112 B1ena,129 Cenchmusbiflorus, 55, 56,88,92,120; ciliarus,150 Bo1baxcostaRtUm, 57 Cephalosplaerra,130 Borassus:aetluiipurn, 57, 69;flabell(fer, 57, 58 Ceraria,141, 145; longepedunculafa,141; narnaquensis, Ioscia,120, 122, 124, 140, 141, 145, 146, 150; 141 albitrunca,137, 138,140, 145, 146,150; angusIfolia, Chaetacrnearistata, 157 156;coriacca, 90, 123; microphylla,150; mossambi- C nasmopodiimcaudatum, 67,70 censis,156; rclnmanniana, 150; senegalensis, 55,87, Chtionalithusfoveolatus,146 89, 92 Cliloris:gayana, 150; prieurii,56; virgata,137. Boswellia,89; carted,93; dalzieli,57; neglecta,90; CIhoroplhora,74;excelsa, 73, 109, 110, 112, 160; regia, papyrifera,94,95 70,76 Brabeiumstellatifoliumn, 144 Chrysocoma,139 Brachiiariabrmchylopha, 75 Clirysophyllum,72,126,130; albidum, 130; Brackylaenta,157 gorungosanum,164; inegalisnontanum, 160,164; Brachystegia,108,109,124-29,148,149,155, 156,159; perpulchrum,74 allenfi,155; bakemrna,159,161,163; boehmii,125-27; Chrysopogonaucheri var. quinquepluris,120 148, 152-154, 156,159, 160, 162; bussei,155;floni- Clappertoniaficrfolia,75 bunda,152,155,160;glaucescens, 153,155,160; Cleistanthusschleckteri,157 gosswieleri,152, 154, 159; laurentii, 113; longifolia, Cochlospernumangolense, 155 159, 160;macrophylla, 159; manga, 156, 160,162; Coeiachyrum:brevifalium, 54; compressa,53 microphylla,155, 160; spiciformis,108,123, 125-27, Cola,74; cordbfolia, 98; greenwayi, 164; laurifolia, 57; 148,152-56,159-62; stipulata,156,160,162; nitida,76 tamarindoides,155; taxifolia, 108,153,155,160; Colophospermummopane, 136,139,141, 144-46, utilis,159,160; wangennecana,154,-159 148-52,156,163 Bridelia,155;ferruginea, 75; taitensis, 91 Combretodendron,72 Bruguieragynnorrhiza,129 Combrehum,66,68,95,97,107,120,123,124,126,128, Buddleja:cornugata, 139; polystachya, 96; saligna,138 140,141,145,146,148-50, 152,154,155,159; Burkea,152,153; africana,58, 6466, 105, 107, 110, aculeatum,91, 106,123; africanum,89; apiculatum, 130, 145, 146, 148, 150-53, 155,156,161 140,141,150, 151,153; binderanum, 120,124, 128; Burttiaprunoides, 156 collinum,95,130,138, 150, 153, 156;cordofanum, 92, Busseamassaiensis, 123, 156 94;dinteri, 152; elaeagnifolium, 123,128; Butyrospermum,56,57; paradoxurn ss. niloticrum,128; ehzeagnoides,155; engleri, 153; ghiasalense, 120,124, parkii,65,66,68 128;glutinosum, 56, 57;hartmannianum, 94,95; Buxus,87,93; hildebrandtii,93 imberbe,148-50,163; kraussii,157,158; mechowianum,123,126,152,156; molle,88,91,97, Cadaba,90;farinosa, 123 120,124,128; schumannii,129; trothae,123; zeyheri, Cadia,13; purpurea,93 120,124,128,147 Caesalpiniatrothae, 91 Commiphora,37, 40,57,89-93,107,119-24,140,141, Calanmusdeeratus, 74 144-46,14850; afriicna,53,55,56,65,87,90,92, Calligonumcomosum, 55 95,123,138, 150; angolensis,138,141, 144, 150; Calotropisprocera, 87 boiviniana,89,90; caerulea,122; campestris, 90; Canariumschweinfurthii, 74 glandulosa,140; )harveyi, 147; hornbyi. 123; Cannamoisnitide, 143 -madagascariensis, 122;merkeri, 122, 123; mollis, 122, Canthium:burttii, 160; glabrifolium, 76 141,149; mossambicensis,150; pyracanthoides, 146, Capparis, 65; erythrocarpos, 75 150; schimpri, 122,150 Carapaprocera, 74 Conocarus,89; ereclus, 77 Cardenia,66,68 Copaifenibaumiana, 159,161 Carexmonostachya, 87 Cordiagharaf, 147; millenii, 130;ovalis, 120 Canissaedulis, 93,123,124 Cordyla, 123; africana, 148,156; densmy7ora,123 Cassia:acutifolia, 87; singuena, 88,91 Cornulacamonocantha, 53 Cassineperagua,146 Cotyledon:paniculata, 141,145; wallichii,143 Cassipourea,126,130,157,160 CmhfitdbF#tkaudata ss. burti, 123 Inidexof Boloniicol Nantes 181

Craterispcnmnniilaturinumn, 76 Ely!wpappus, 146; rhiinocerotis, 142, 143 Crossonephaelis(Meatinodiscu$s oblonigus, 161 Enitadaafricana, 58, 66,68 Crossopteryxfebrifiega,155 Entadopsis abyssinica, 91 Croton,9'5, 97,123, 157;inwgolobotrys, 163; scorciesii, Entanldrophraguw,72, 73, 130; ongtolense, 130; 75;subgrmttissimus, 146;zamtbesicuis, 146 catidaturn,153; cxcelsum, 130 Crudiagabonensis, 72 .Eragrost is,53,58, 124, 137, 138;pollens, 151; Cryptocar'yalatijolia, 158 trentuda,57. Cryptosepalutm, 153, 159;exfoliatunm, 152, 155, 160,161; Efrica,121, 128, 129, 139, 143; arbo rea, 87 nwaraviense,159; pseuidotoxus, 161 Eriocaplhalus:africanzus, 143; mocemosus, 144; Cteniuun:e)egans, 67; iwewtonii, 57 un:bellulatus,144 Cunoniacopensis, 144 Fry!lhrina: abyssinica, 95; socleuxif, 129; tomentosa, 113 Curtisiaden Ita,a 158 Fiytlfrnophleum,152,153, 155.162; africanump, 58, 107, Cussonia,93, 138;angolensis, 159; borteri, 58; holstii, 152,155, 156,161; guineense,57, 58, 70, 98; 94; lo'gissimo,70; spica to, 165;umibellifero, 165 suaveolens,160, 161 Cymbopogont:giganfteus, 57; ?nionocan2tha, 53; nenat us, Eucalyptus,33, 93, 94, 98, 99, 165; globus,93, 99;

86,88 . granolis,165; saligna, 165

Cynodonhirsutus, 138 . Euclea,93, 123, 124,142, 153; crispa,138; divinorum, Cynomebra:alexandri, 111, 113,131; leonenisis, 72; 124,125; notolensis, 157; pseudebenus, 137; macenosa, megalophylla,75 124, 158; tomentosa,141, 146; undulata,141, 146, 150 Cyperulspapyrus, 88 Euphorbia,88, 91, 93, 97, 98, 120-24, 141, 144, 145; CyphostemanurrorCIiT,145 abyssinica,88; balsamitPm,56; ca-ndelabrum,89,93, 149;conspicua, 149; dowei, 131;grondis, 94; Dalbergia,92,94,123, 126;melanoxylon, 95. guercidiona,145; mauritanica, 143; mobecchii, 90; Dalbergiellanyasae, 155 tirucalli, 126; trionguloris, 157 Daniellia,58; alsteeniano,155; oliveri, 57,58, 67,68,70, Eupharphzia:currornt, 145; eduordol, 145

107,110 .Eustachys paspaloides,120 Delonixelata,123 Exothecaabyssinico, 123, 129 Deschompsia,123, 129; caespitosa, 87 Dialiumengleranum, 152, 161 Faurea:sotigno, 95,96,155, 156;speciosa, 153 Dichtrostadnjs,149; cinerea, 137,138, 140, 141,146, Festuca,123,129,139 147,150; cinerca ss. afiicana, 147; glomerata, 76 Ficalhioalaurifolial 111 Didelotiaunifoliolata, 72 Ficus,91, 141, 147,157, 159; acrocarpo , 88; capensis,75, Digitariamacroblepharno, 120 147;cordata, 150; guerichiana, .150; ingens, 141;. Diospyros,72, 123, 138, 161; abyssinica,75, 164; sycomonus,98,137,163 oustrno-africana,142; dichrophylla, 158; glabra, 158; Flacourtiaindira (flavesce ns), 75 kirkit 56~f;lydioides, 138, 154;mespiliformnis, 75, Frey/intaopposibjfolia, 144 128, 'it4toeonsis, 156;rotundifolia, 157; 4L?Ws#Whyteana,153,165 Galenioafricona, 143 44 6 E1fllo/4yg41j$4W3' ndylocarpon,123,126,155,156 Ga/intemt,100 bzn~~~~h4g~~~p,ti~~~s~Gardenia jovis-tonantis,123 Dissolts corn ~~~~~~~~~Gilbertiodendron,113;dewevnei, 72, 106, 107,113;

Dobera,90 . ~~~~~~~~~preussi,7 D doac iSco2,9S, Xfl, 124 Glumaivorensis, 72 Domnbeya,123; eryt hroZeu ica, 165; goetzenii , 129; Grewia, 90,91, 122,123, 137, 146, 150,157; bicolor, madiensis,123; rotund ifo lia, 141, 150 125;burtii, 123; ca rpinifolia, 75;fa Ilax, 120;fiava, 140, Drcacenaschizantha, 93,94 141,145, 150; occidenitalis,138; villosa,150 Drokebrockmninasomakensis, 119 Guanoa,72 Drypetes:flonlrunda,75; gerrardii, 157; parv4folia, 75 Guibourtia,152; coleosperma, 152,159,161; coleosperma Duosperma enemo philum, 119 ss.pseudotaxa,l 161; demeusei, 107,112

Ecbolium,91 Hogenia,99,121, 130,164; abyssinica,86,98-100,121, Eh-retiarigida, 138,141, 145 129,164; benguelni,165 Ekebergia, 93, 99; copensis,157, 160 Hizre aciculanis,144 Elaeisguineensis, 70,76,109 Hallerialucida, 99,147,153, 158 Elaeophorbiadrupifera, 75 Hartogiacapensis, 144 Eleusinecompresa, 53, 55 Horunganamtadagascariens is,76, 160 182 EstimatingWoody Biomnss in Sub-SalramnAfrica

Heenca(Ozorea), 151; argentea,143 Lowuaszuynnertonii, 161 Helichyysum,139 Lyciun, 140 Heritieralittoralis, 129 Hildegardiabarteri, 128 Macaranga,126,130; capensis,160; kilimandsclarica, Hippocratea,123 130 Hirtella, 162; zanzibarica, 162 Mamnra,91, 123; anolensis, 91; caffra, 158; crassIfolia, Hohmrrhenaflonlbunda,128 87, 88, 92; lanceolota,147 Hymenocardiaacida,105,106,110,153 Maesopsis,125; eminii, 130 Hyparrhenia,66, 67, 97, 106,120, 122, 128-30; Malacanthaadnifolia, 128 anthistirioides,86, 88; chrysargyrea,75; confinis, Mangiferaindica, 57,76,148 105; cyanescens,58; dissoluta,57; rufa,86 Manzilra: obovata,75,128; sansibarensis,129 Hypericum, 121; revolutum, 121 Mansoniaaltissima,74 Hyphaens,89; benguelensis,124; thtebaica,57,66,87; Mapania,72 ventnicosa,148, 156 Maprouneaafricana, 95, 96 Hyptis spicigera,75 Maranthes:goetzeniana,161; polyandra, 95, 96 Markhamia,123; obtusifolia, 149,156 Ilex mitis, 99, 129,144,153,158,162,165 Marquesi acuminata,155; calonerus, 159; katangensis, Ionchocarpuscapassa, 163 159;loadensis, 155; macmura, 108,109,155 Isoberlinia,58,64,66, 94-96, 98,107-09,124,127,130, Maytenus, 153;acuminata, 143; heterophyia,142,146; 160,161; angolnsis, 125, 154,159; baumii,161; doka, okoides,143, 144;senegalen t ;, 65, 147 58, 65-68,107,124; paniculatai,125; scheffleni, 130; Melaodiscus see Crossonephelis ftmentosa, 58, 125,156,160,162 Metaksia municata,144 Metrosiderosangusfifolia,144 Jatropha, 120 Milettia, 126; gmndis, 157; stuhimannif, 160; lbernardia,108, 109, 124,126, 127, 129, 149, 153,156, thonningii,75 159;gloflora, 125-127,148, 152, 153,155,156, Mimusop: coffra,l57;fuifosa, 90; obovata,157 160-62; magnistipulata,125-27, 129; paniculata,152, Mitragyna,112; cliata, 74; inermis 57; stipulosa,74,98 154, 156,159-62; seretii,72, 111, 113 Monechma,145 luncusarabiats, 86 Monodonamyristirc, 130 Iuniperus,92-94,99, 100; procera,86,87,93,98-100, Monotes,124,125,138.152; africanus,148; kerstingii, 129,164,165 58,67,68,95,96,107 Montiniacaryophyllc, 150 Khaya,73, 95, 130; anthoffieca,110; grandifolia, 98; Moningaoalifolia, 145 nyasica,160; senegalensis, 57,58,68,98,106,107 Morus, 159 Kigelkaafiicana, 158 Mucronata,137 Kiggelariaafricana, 165 Musangacecropioides, 76, 106, 110, 112 Kirkia acuminata, 140, 148-50 Myrianthus holstfi, 164 KIzinedoXagobonensis, 112 Myrica, 130;salicifolia, 165 Koeleria,123 Myrsineafricana,146

Laguncularia,77; racemosa,77 Nauclea,74; dideichii, 72 Lannea,123, 129; microcarpa,58; stuhlnmannii, 148, 150 Neoboutonia,126,130; macnocalyx,130 Lantanacama, 125 Nesogordoniapapaver Ifera, 75 Lebruniabushaie, 111 Newlonia,130; buchananii, 124,130,160,161; Leptadenkapynotechnica,53,55,88,92 hldebmandtii,157 Leptospernmum:laeoigatum, 142; argenteum, 144; Nuia, 98,130; congesta,99,129, 165;florlbunda,158, coniferum,144; eucalyptifolium, 158; salicifolium, 144; 165 muinii,144 lxucosideasericea,139 Ochna,157; afzelii, 95; ho!stii,164; pulchra,138,146, Limosellaafrina, 87 150,151,153; schwveinfurthiana,95,153 Lobelia,121; rhynchopetalum, 87,99 Ochthocosmusafricanus,113 Lonchocarpus,126; nelsii,146,150 Ocotea,130, 165;bullata, 99, 158; usambarensis,111, Lophira,67, 70; alata,70, 72; lanceolata,57,58, 67, 70, 121,129,130 95,96,110 Oldfweldiaafricana, 72,73 Loudelia,70, 130; demonsii,105,106; phragmitoides,75; Ole0nafricana, 86, 93,98,123, 124, 138, 143;capensis, simplex,57,70,129,163; superba,67 129,143,144,164; weltwitschii,130 Indexof BotanicalNames 183

Olinic emarginata,153; usambarensis, 96, 165; ventosa, 143 Pterocelastrus,165; tricuspidatus,146 Opuntia, 96,97 Pterolobiumstellatum, 91 Ormocarpumtichocarpum, 125,140, 147 Pteroniaglauca,143 Ostryoderris,126 Pterothrixspinescens,143 Osyris, 138,142 Putterlickiapynicantha, 146 Oxystigmaozyphyllum, 113. Oxytenant'-era:abyssinica, 57, 58, 95, 97; borzii,95 Ranolfiacaffrn, 157 Ozorensee Heeria Rapanea,130, 165;melanophloeos, 99 Rap/lia,74, 112 Pachypodium,145 Rwsonia lucida,165 Pachystelabrevipes, 160, 161 Rlhania, 143 Pandanus candelabrum, 74 Resiio cwmirUmis, 143 Panicum, 122;coloratum, 137; kuahurense, 138; Rhigozum,150; brevispinosum,140; tridciotomum, 137, naximum, 125,151; turgidum, 53,55,88,120 145; virgatum,144, 145 Parinari,126,130,161,164; curatellfiflia,153, 155,156; Rhizophora,77, 85, 129;harrisonii, 77; mangle,77; excelsa, 70,74,108,129,130,164 racemosa,77 Parkia,66, 68; biglobosn,56-58,70,107; -Rmus, 138,142, 146, 158; lancea,137, 138, 154;marlotii, clappertoniana,58 141,150; pyroides,140; quartiniana, 163; tenuinervis, Paropsiabarzzeana, 153,161 146 Passerina,158; montana, 139 Ricinodendronrautanenii, 153 Pdtophorumnafricanum,145,146,150 Ruschitferox, 143;mulEtflora, 143 Pennisetum,58, 124,129; mezianum,120; Rynchelytrumrepens, 126 pediceLlalum,57 Pentadesmalebrunii, 111 Sacoglottisgabonensis,72 Pentschistis, 123 Salix, 154 Pentzia, 143; incana, 143 Salsola: aphylila, 137; tuberculata, 137 Petersianthus macrocarpus, 112 Salvadora, 91; persica, 137 Phaeoptilumspinosum, 144 Sansevieria,93,120, 124 Philippia,129,158; bengueensis, 165 Sarcocephalusdiderrichii,112 Phoenixreclinata, 74, 112 Scaeola thunbergir,157 Phragmitescommunis, 86 Schizackyrium,58, 124;sanguineum, 58 Phylica,143 Schmidtin, 138 Piliostigma, 58,148; thonningii, 58,70,109,155,156 Schoenefeldiagracilis, 55,56,86 Pinus. elliottii, 165; patula, 165; pinaster, 144; taeda, 165 Schrebematrichoclada, 149 Piptadeniastrumafrianum, 112 Schuma ischaemoides, 86 Pittospoiumviridcflonnm, 165 Scleriabarteri, 76 Pleurostyia, 126 S-lerocarya,126; birrea, 147; caffri, 140,141,146-48, Poa, 123, 129 150 Padocpus, 93,94, lit 130,158,165; elongatus,143; Scolopiamundii, 158 faluatus, 99,130; gracilior, 93,98,99; latifolius, 129, Scorodophloeuszenkeri, 113 153,165; milanjinus, 121, 130; usambaren1sis,127 Securinegavirosa, 75 Polyscias,126, 128,130 Senecio,121 Populus, 154;deltoides, 165 Sericocomopsis,91 Protea,108, 138,144,146,153; cynaroides,158;gaguedi, Sesamotlamnus,141,145 156;madiensis, 95; nere folia, 142; obtusifolia, 144; Setaria, 122,129; incrassata, 86,88; welwitschii, 149 susannae,144 Sideroxylon,94,100 Protorhuslongifoli, 157 Smihaxkraussiana,126 Prunus afrcana, 98,99,128-30,158,164,165 Sorghumpurpureo-sericeum, 86, 88 Pseudolacdnostylis naprouneifolia,148,155,156 Sorindei madagascariensis, 90 Pseudoprosopsisfischeri,123 Spirostachysveifera, 90 Psorospermum,156 Spondianthuspreussii,74 Ptaeroxylonobliquum, 157,158 Sporobolusrobustus, 122 Pteleopsis,162; anisoptem, 153;diptera, 155 Sterculia,91, 123, 148, 156;appendiculata, 160; setigem, Pterocarpus, 148,156; angoensis, 152,155,156,159; 149; tragacantha, 76 antunesii,148, 153;erinaceus,57,58, 67, 68, 70; Stipagrostis:pungens, 53,55; uniplumis, 53 rotundifolius, 140 Stroinbosiaschefe, 130 184 Estinating WoodyBiomnass in Sub-SahNamnAfrica

Sthychnos, 123,130; spinosa, 144 Trichflia: dregena, 157; emefica, 90, 157; quadrensis, 161 Suaeda monoica, 122 Trichodadusellipticus, 165 Superbiagrandis, 93 Triplochiton sckroxylon, 74, 109 Swartzia madagascarmensis,153 Turm holstii, 130 Syderoxylon inerme, 158 Turrueanthus afiicana, 73 Symphonia, 128;globuliJera, 74,111,112 Syzygium, 157,162; condatum, 147; guineense, 70, 98, ULapaca,108,124,126,138,153,155,156,159; 108,123,126,155, 156, 16C, 16t; guineense ss. guinensis, 70,74,112; heudblotii, 74,107,110; afromontanum, 129;guineensess. barotsense, 163; kirkiana, 125,148,153; pilosa, 159; somon, 58; guinaense ss. guineense, 153; pamifolium, 127 togoensis, 68 Utenium elegans, 57 Tabernuemontana, 126,130; angoensis, 164; Uria dhamae,75 johnstonii, 129 Tamarinidus, 57, 126; indca, 57,65 Vaccinium, 129 Tamarix manniram, 86 Vangueriopsis lancifzlia, 153 Tapiphyllumflonlundum, 23 Vepris heterophylla, 75 Tarchonanthus camphoratus, 93,123,124,141,146,150 Ventonia ampla, 147 Tarietia utilis, 72 Virgilia oroboides, 158 Teclea, 93, 123,124; isheri, 156; nomb7is,164 Tennridia, 66,68,74,91,92,120,123,124,130,140, We!wiftsha bainesii, 136 149-51,155; avicennioides, 58; bnzchystemnm, 153; Widdringtonia, 158; cedanrbgensis, 143,144; brownii, 95, 97, 120, 128; glaucescens, 70,95,120, cupresoides, 98, 100,143,144,164; nodjffoni, 165; 124,128; axkjlora, 107; moolis,120,125,128; schwa rzi, 144 prunoides, 136,140,141,150,15Z, seric, 109,120, Wilkenowia srh*ta, 146 137,13B,140,141,145,146,149-53,155.156; superba, 109,110.112; utilis, 72 Xanthocerdszambesia, 157 Tetraberlinia tubznanina, 72 Ximenia, 150; amercana, 58,140; caifra, 146 Thamnochonruserectus, 144 Xylopu, 162Waethiopica,160; odoratissinm,161; Themeda, 120,122,138,139; triandra, 97,120,123,129, quitasii, 76; rubescens, 112 137,138 Xymalos monspora, 158,165 Thepesidanis, 90 Tieghemeila (Dumoria) african, 72; hockelif, 73 Zanthoxylum xanthoxyloides, 75,128 Torchonanthus camphoratus, 93 ZilIa spinosa, 86 Tragus racemosus, 55 Ziiphus, 57; abyssinica, 88,91,106; mauritiania, 56; Trema:guinensis, 76; onentaits, 160 mucronata, 137,138,140,141,146,150,152,154 Tribdus, 53 Zyguphyllunvgiqlya=ni 143; morgsana, 146 Index of PlaceNames

Abeokuta (Nigeia), 69 Banikoara (Benin),65 Aberdare Mountains, 25,121,129 BarclayEast (South Afica), 139 Aberdae National Park (Kenya), 37,121 BarclayWest (South Africa), 151 Abidjan (Cbte d'lvoire), 67 Ban Region (Somalia), 85 Accra (Ghana), 67,73 Barotseland (Zambia), 163 Addis Ababa (Ethiopia), 93,95,96,98,99 Bas Zaire Province (Zaire), 108,109 Adoumaoua, Massif of, 110 Batek6Plateau, 105 Adrar des if oras Plateau, 54 Bauchi State (Nigeria), 65 AfoU4,Massif of, 55 Begemder Province (Etlhiopia),88,92,94 Air Mountains and Plateau, 53,54 Beira (Mozambique), 27 Aksum (Ethiopia), 95 Beitridge (Zimbabwe), 146 Alantika Mountains, 107 Bendel State (igeria), 71 Alexander Bay, 136 Benguela (Angola), 149 Anambra State (Nigeria), 74 Benguela Province (Angola), 77,143 Anhanca (Angola), 141 Benue River and Valley, 66 Ankober (Etiopia), 87 Benue State (Nigeria), 74 Ars! Hills, 97 Berbera (Somalia),89 Arsi Mounis, 86 Bethlehem (South Africa), 138 Arsha CTanzania),123 Bethulie (South Africa), 151 Arusha Region (Tanzania), 120,121 Bie Plateau, 152,159-161,163 Asbestos Mountins, 139,141 BieProvince (Angola), 155,159,160 Asmera (Ethiopia), 87,88,94 Biagds Islands, 76 'Assiba Escarpment, 55 Biknar, Parc Nacional da (Angola), 164 Atcora Mountains (Chaine de lAtakora), 65, 68,71 Birao (Central African Republic), 106 Atbara River, 88, 95, 96 Black Volta River, 65 Awash River, 88 Blantyre (Malawi), 148,156 Awash Station (Ethiopia), 96 Bloemfontein (South AErica),138 Blue Nile Province (Sudan), 91,94,95 Badda Mountains, 99 Blue Nile River, 86,94,95, 96 Bafata Region (Guinea-Bissau), 69 Bo (Sierra Leone), 69 Bahr al Ghazl Province (Sudan), 95 Bobo Dioulasso (Burlina Paso), 57 Bale Mountains, 86 Bokkeveldberge Range, 142 Bale Province (Ethiopia), 89, 97, 98 Boma Hills, 92 Bamako (Mali), 56 Bophuthatswana, 137,138,149 Bamenda Hills, 69 Bora (Ethiopia), 92 Bam-ilekePlateau, 111 Bomo State (NiLgeria),65 Bandundu Province (Zaire), 109 Brazzaville (Congo), 34,105,109 Bangala (Zaire), 107 Buyenzi District (Burundi), 128 BangweuLuSwamp, 156 Bwanje Valley, 156

185 186 EstirnatingWoody Biomass in Snb-SalwamnAfrica

Cabinda (Angola), 28,38, 109, 111 Dembos cloud forest, 159,160 Cabo Delgado Province (Mozambique), 159, 160, 164 Dese (Ethiopia), 87,95 Cacheu River, 76 Desert of Moq&medes,136, 141,143, 145 Cacine-River, 76 Didinga Hills, 92,99 Cale-Jon Valley, 151 Dire Dawa (Ethiopia), 93,96,97,99 Calvinia (South Africa), 143 EJambala (Congo), 106 Cape Barracouta, 143 Djougou (Benin), 67 Cape Mountains, 143 Dochire (Ghana), 65 Cape Province (South Africa), 24,25,39,40,136-39, Dodoma Region (Tanzania), 120 141-46,149,151,154,158,159 Dongoroma Range, 67 Cape St Lucia, 157 Dongotona Hills, 92 Cape Town (South Africa), 143,144,146 Dongotona Mountains, 99 Caprivi Strip (Namibia), 149,151,152 Dorsale du Kivu, 111 Casamance River and Valley, 57,76 Douala (Cameroon), 110 Cedarberg Ranges, 142,143 Drakensberg Mountains, 39,138,139,147,149, 157, Central Highlands (Kenya), 121,123 158,164 Central Highlands (Tanzania), 125 Durban (South Africa), 157 Central Province (Zambia), 159 Ceres (South Africa), 143 East London (South Africa), 158 Chaine de l'Atakora (Atacora Mountains), 65,67,71 Eastern Equatoria Province (Sudan), 89, 93, 95, 99 Chaine de Madinani, 67 Ebrie, Lagune (Cote d'Ivoire), 75 Chaine de Tlem6, 67 Ehi, Lagune (C6te d'Ivoire), 75 Chalbi Desert, 119 EI'Atrun Oasis, 87 Chambeshi Valley, 162 El Buheyrat Province (Sudan), 95,96 Changane Valley, 141 El Bukeyral (Sudan), 86 Chela, Serra da, 141,163,164 El Milk, 87 Cl'erch'er (Ethiopia), 92 El Obeid (Sudan), 34,91 Chiange (Angola), 149 Ennedi Plateau, 54 Chimanirnani Mountains, 165 Enugu (Nigeria), 68 Chobe Region (Botswana), 149,163 Equateur Province (Zaire), 112 Chobe River and Valley, 162,163 Equatoria Region (Sudan), 32,89, 92, 93,95-99 Choke Mountains, 86 Eritrea, 85, 88, 89, 91, 92, 95, 98 Choma (Zambia), 148,149 Erkowit Hills, 87 Circonscription Administrative de Dapadong Ermelo (South Africa), 147 (Togo), 65- Est, R4gion de l' (Cote dIvoire), 67 Ciskei, 138,158,159 Etosha Salt Pans, 136,137,143,149,150 Conakry (Guinea), 76 Evale (Angola), 141 Copperbelt Province (Zambia), 159 Corubal River, 76 Forecariah Plains, 73 Cradock (South Africa), 138 Foret du Day,87, 92,93 Crater Highlands, 129, 130 Fouta Djailon, 31, 69,73 Cross River and Basin, 71,76 Franceville (Gabon), 105 Cuanza Norte Province (Angola), 155 Cuanza Sul Province (Angola), 155 Gabu Region (Guinea-Bissau), 66,69 Cunene River and Valley, 152,163 Gambaga Scarp, 64 Gambia River, 77 Dakar (Senegal), 56 Gamo-Gofa Province (Ethiopia), 89, 93, 96, 97 Daloh Forest, 92, 93 Gamioos Valley, 146 Danakil Alps, 85 Garamba, Parc National de la (Zaire), 110 Danakil Depression, 85 Gash Delta, 88 Danakil Desert, 85-87 Gaza Province (Mozambique), 161 Dapadon& Circonscription Administrative Geba River, 76 de (Togo), 65 Gemsbok National Park (Botswana), 145 Dar es Salaam (Tanzania), 127,129 Geneale Valley, 90 Darfur Province (Sudan), 34,87,88,91,94 Gezira-Managli (Sudan), 88 Day, Forat du, 87,92, 93 Ghanzi District (Botswana), 137 Indexof PlaceNames 187

Ghanzi Ridge, 150 Juba River and Valley, 34,89,90,91,97 Ginir (Somalia), 90 Jubbada Dhexe Region (Somalia), 90 Gogu Mountains, 97,99 Jubbada Hoose Region (Somalia),90 Going Range, 67 Gojam Province (Ethiopia), 88,92,94,95,97,98 Kaap Plateau, 139,141, 151 Gola Hills, 73 Kaduna State (Nigeria), 65 Gola Mountains, 71,72 Kafue Flats, 155 Gonder Province (Ethiopia), 96,98 Kagera River, 130 Gori Hills, 73 Kakamega Forest, 38,127,130 Grahamstown (South Africa), 158 Kalahari Desert, 24,35,39,40,105,136-38,140,141, Grand Bassa County (Liberia), 72 144-46,149,150,152-55 Grand Gedeh County (Liberia), 72 Kalale (Benin), 67 Great Berg River, 142 Kalemie (Zaire), 109 Great Karas Berg 149 Kananga (Zaire), 105,109 Great KCarroo,39,136, 144, 145 KCandi(Benin), 65 Greenville (Liberia), 72,75 Kandoli Mountains, 160 Grootfontein (Namibia), 150 Kaniama (Zaire), 105 Guinea Highlands, 67 Kano (Nigeria), 31,65 Gulf of Tadjoura, 87 Kaokoland Escarpment, 150 Karora Hills, 86,87,92 Hanam Plateau, 141 Karsa Dek (Ethiopia), 97 Harare (Zimbabwe), 148,156 Kasai Basin, 105 Hardeveld Range, 142 Kasai Plateau, 105,109 Harer (Ethiopia), 93,94 Kasai Province (Zaire), 108,109 Hirer Hills, 92, 95, 96 Kassala (Sudan), 87 HIrer Mountains, 97 Kassala Province (Sudan), 87 HIerg Hills, 97 Kefa Province (Ethiopia), 97-99 H:rerge Province (Ethiopia), 87,87, 93,96,98 Keren (Ethiopia), 87 Harper (Liberia), 75 Khartoum (Sudan), 26,89,92,94 Harismith (South Africa), 147,157 Khartoum North (Sudan), 89,92 Haut Uele (Zaire), 107 Khasbim El Girba (Sudan), 8B Haut Zaire Province (Zaire), 111, 112 Khor Abu Habi River, 88 Ilighveld, 140,147,165 Kigoma Region (Tanzania), 125 Hiwa, Wadi, 87 Kilimanjaro Region (Tanzania), 121 Hodh Basin, 55 Kilimanjaro Forest Reserve (Tanzania), 129 Holawajir Forest, 90 Kilwa Kivinje (Tanzania). 129 Huambo (Angola), 1,54,162,163 Kimberley (South Africa), 138,139,141,151 Hufla Province (Angola), 155,160,163,164 King William's Town (Soutli Africa), 158 Hunyani Range, 148 Kinshasa (Zaire), 34 Hwange (Zimbabwe), 153 Kisama, Parc Nacional da (Angola), 164 Kisangani (Zaire), 113 lbadan (Nigeria), 69 Kisiji (Tanzania), 129 l:le1-dra, 77 Kisimaya (Somalia), 90 leornf(dira a), 68 Kissidougou (Guinea), 69 ilubabor Province (Edtiopia), 96,98,99 Kivu, Dorsale du, 111 Imo State (Nigeria), 74 Knysna (South Africa), 158 Lnhambane (MozaIbique), 159 Knysna Forest, 158 Inhambane Province (Mozamnbique),147,161 Kokstad (South Africa), 158 Inyanga National Park (Mozambique), 161,165 Kolwezi (Zaire), 34 hinga Region (Tanzania), 125 Komponi River, 76 Kopargo (Benin),67 Jebel Gurgei (Sudan), 88,89,94 Kopshom, 138 Jebel Marra (Sudan), 94 Kordofan Province (Sudan), 34, 86, 91, 94 Jong River, 76 Korem (Ethiopia), 87 Jonglei (Sudan), 86, 94 Kouand6 (Benin),67 Jos Plateau, 64,66,67,69 Kougaberge Range, 139 188 EstimatingWoody Biomass in Sub-SalmranAfrica

Koundara (Guinea), 69 Lunda Norte Province (Angola), 155 Kourandou Range, 67 Lunda Sul Province (Angola), 159 Kruger National Park (South Africa), 140,141, Lunga River, 162 142,149 Lunsemjwa Valley, 155 Kuando-Kubango Province (Angola), 152,154, Lurio Valley, 148 160,163 Lusaka (Zambia), 159,164 Kwango (Zaire), 105,109 Kwango Basin, 105 Mabebe Depression, 150 Kwanyama (Angola), 162 Macondes Plateau, 161 Kwara State (Nigeria), 74 Madder Valley, 138 Kwazulu, 147 Madinani, Chaine de, 67 Mafeteng (Lesotho), 138 Ladysmith (South Africa), 157 Makgadikgadi Pan, 136,137,149 Lagos State (Nigeria), 74 Malanje Province (Angola), 155,159 Lagune Ebrie (Cote djIvoire), 75 Malindi Region, 148 Lagune Ehi (Cote d'Ivoire), 75 Malmesbury (South Africa), 142 Lagune Taio (Cote d'Ivoire), 75 Mandara Hills, 69 Lake Chad, 10,106,107 Mandara Mountains, 106,107 Lake Edward, 131 Manding Region, 30,54 Lake Kariba, 151, 162 Manica Province (Mozambique), 159,161,164 Lake Malawi, 25,37,125,126,128,148,156,159,162 Maputo (Mozambique), 157 Lake Nyasa, 122 Maramba (Zambia), 151 Lake Rukwa, 121-123,126 Margherita (Somalia),90 Lake Tanganyika, 109,125,126,128 Marsabit District (Kenya), 119 Lake Turkana, 119 Martin's Drift (Zimbabwe), 162 Lake Victoria, 28,37,38,121,122,125,127, 128, 130 Maseru (Lesotho),138 Lake Victoria Basin, 37,38,127,128,131 Massif de l'Adoumaoua, 110 Lake Victoria Esrpment, 37 Massif of Afoll, 55 Lake Volta, 67,73 Matabeleland (Zimbabwe),140,147,149, 151,153, Lamto (Cote d'Ivoire), 69 359,164 Langeberg Mountains, 139,141 Matatiele (South Africa), 138 Laupula Province (Zambia), 159 Matopo Hills, 151 L6fini River and Valley, 105,106 Mavia, Planalto, 164,165 Libreville (Gabon), 109 Mayumba Forest, 112 Libyan Desert, 85-88,91 Mbandaka (Zaire),112 Lichinga (Mozambique), 164 Mbeya Region (Tanzania), 121,125 Lilongwe (Malawi), 148 Mbuji-Mayi (Zaire),109 Lilongwe Highlands, 156 Mendebo Mountains, 99 Lilongwe Plateau, 148 Middelburg (SouthAfrica), 138 Limbe (Malawi), 156 Middleveld, 147 Limpopo Escarpment, 153 Moqfmedes, Desert of, 136,141,143,145 Limpopo River and Valley, 140,141,146,149, 151, Mofimedes Province (Angola), 163 153,157,162 Mogadishu (Somalia),91 Lindi Region (Tanzania), 125 Mogalakwena Valley, 140 Lobito (Angola), 144,149 Mogol Valley, 140 Loma-Man Dorsale, 71 Mohokare Valley, 137 Ltolawajir Depression, 90 MokhotlongDistnit (Lesotho), 138 Luanda (Angola), 164 Mont Bowe de Kiendi, 71 Luangera Valley, 155 Mont Nangbion, 71 Luangwa Valley, 39,148 Mont Yev6l, 67 Luapula Province (Zambia), 155,156 Montserrado County (liberia), 72 Lubango (Angola), 149 Morogoro Region (Tanzania), 120 Lubombo Hils, 147 Morro de Moco, 162 Lubumbashi (Zaire), 34,35,108,109 Mount Bend, 69 Luganda River, 159 Mount Cameroon, 110 Luisnishi (Zaire), 108 Mount Gakarosa, 139 Index of PlaceNames 189

Mount Frere, 158 Oio Region (Guinea-Bissau), 69 Mount Goda, 87,92 Okavango River and Delta, 40, 149,162 Mount Kenya, 36,129,130 Okavango Swamp, 163 Mount Kenya National Park (Kenya), 129 Olokemeji (Nigeria), 128 Mount Kilimanjaro, 36,121,129,130 Omatako River, 162 Mount Mulanje, 162 Omdurman (Sudan), 89,92 Moxico Province (Angola), 159,161 Omo Valley, 90,91 Moygua (Angola), 141 Ondo (Nigeria), 69 Mpama catchment, 106 Ondo State (Nigeria), 74 Mudug Region (Somalia), 85 Orange Free State, 24,25,137-39,141,149,151, Mugamba District (Burundi), 128 153,157 Mulanje Massif, 160,164 Orange River and Valley, 136,138,141,151 Mwenezi River, 140 Otecbinjan (Angola), 149 Mweru Swamp, 156 Ouake (Benin), 67 Mwinilunga (Zambia), 162 Oubangui River and Basin, 107,110,111,112 Ovamboland (Namibia), 141 N'Djamena (Chad), 54 Oyo State (Nigeria), 74 N'Giva (Angola), 141 Nababeep (South Africa), 142 Paarl (South Africa), 146 Nairobi (Kenya), 124 Palala Valley, 140 Nairobi National Park (KCenya),129 Parakou (Benin), 67 Namacunde (Angola), 141 Parc Nacional da Biknar (Angola), 164 Namaland (Namibia), 141,143,149 Parc Nacional da Kisama (Angola), 164 Namaland Mountains, 136 Parc National de la Garamba (Zaire), 110 Namaqualand (Namunbia),136,143 Pehonko (Benin),67 Namib Desert, 24,25,39,40,136,139,144,145 P&6r (Benin),67 Namibe (Angola), 136,141 Phalombe Plains, 148 Namibe Province (Angola), 143,154 Piet Retief (South Africa), 165 Nampula (Mozambique), 165 Pietersburg (South Africa), 140,149 Nampula Province (Mozambique), 159,163,164 Piketberg (South Africa), 142 Namwera Malawi), 148 Planalto do Mavia, 164 Nandi Escsrpment, 130 Plateau of Kasai, 105,109 Natal Province (South Africa), 40,147,154,157,158 Plateaux Province (Congo), 105,106 Natitingou (Benin), 67 Pointe Noire (Congo), 34 N&d6l(Central African Republic), 107 Pondoland Region (South Africa), 157,158 Nehone (Angola), 141 Port Elizabeth (South Africa), 27, 137,146,158 Nelspruit (South Africa), 153,158 Port St. Johns (South Africa), 158 N4ro-Mer (C6te d'Ivoire), 75 Port Shepstone (South Africa), 157 Ngamiland District (Botswana), 137 Port Sudan (Sudan), 85, 87,88 Niassa Province (Mozambique), 161,163,164 Potgietersrus (South Africa), 149 Niger River and Valey, 30,64,66,69,74,76,77 Pretoria (South Africa), 137,138,149 Nikldi (Benin), 67 Prieska (South Africa), 151 Nile River and Basin, 54,86,88,91, 92,94, 95,97,98 Pwani Region (Tanzania), 125, 129 NimIruiHills, 73 Nord, Region du (C8te d'Ivoire), 67 Qacha's Nek Distict (Lsotho), 138 North East District (Botswana), 137 Qala 'en Nahal (Sudan), 34 Northem Province (Zambia), 155,159,161 Queenstown (South Africa), 138 Northern Region (Malawi), 160 Quthing (Lesotho), 138 Northwestem Province (Zambia), 155,159,164 Nubian Desert, 85,88 Red Sea, 85,91,92 Nyilca Plateau, 155,164 Red Sea Hills, 34,85-87 Nzdr&kor6(Guinea), 69 R4gio'. de lEst (COted'Ivoire), 67 Region du Nord (COted'Ivoire), 67 Ogaden Region (Ethiopia), 34,85,89 Region du Sud-Ouest (C6te d'Ivoire), 73 Ogooue River, 109. Rift Valley, 24,34,89-92,94,96,97,99,109,111,148 Ogun State (Nigera), 74 Rio Muni, 28,34,109,111,112 190 EstimatingWoody Biomass in Stab-SaliranAfrica

Rio Nunez, 76 Sud-Ouest, Region du (Cote d'Ivoire), 73 River Cess (Liberia), 72,75 Sunyani (Cote d'Ivoire), 73 Roggeveld Region (South Africa), 143 Rokel River, 76 Table Mountain, 10, 146 Rouxville (South Africa), 139 Tabora Region (Tanzania), 120,121,125 Rukwa Region (Tanzania), 125 Tabou (Cote d'Ivoire), 75 Ruwenzori Mountains, 129 Tagant Escarpment, 55 Ruwenzori National Park (Uganda), 129 Tahoua (Niger), 56 Taio, Lagune (C6te d'Ivoire), 75 Sabi Valley, 140,148,159 Tamale (Ghana), 65,66 Sahara Desert, 24,53 Tana Valley, 121 St. Helena Bay, 142 Tanga Region (Tanzania), 120,121,126-28,130 Sand Valley, 140 Tchaourou (Benin),67 Sankarani River, 66 Tete Province (Mozambique), 161 Savanes Region (Togo),65 Teyateyaneng (Lesotho),138 Save Valley, 147 Thaba-Tseka District (Lesotho), 138 Scarcies River, 76 TIhyoloMountains, 160 Scobell's Kop (South Africa), 139 Tibesti Plateau, 53 Sekl'ot'a (Ethiopia), 95 Tieme, Chaine de, 67 Senegal River and Valley, 30, 55 Tigre Province (Ethiopia), 34, 92, 86, 94, 98 Sengu Valley, 137 Tinkisso River, 66 Serergeti National Park (Tanzania), 122,123 Togo Hills, 66 Serengeti Plain, 122 Tokar Delta, 88 Serra da Chela, 141,163,164 Tombali Region (Gabon), 73 Serra Upanda, 164 Tombua (Angola), 141 Sewa River, 75 Tongaland Region (South Africa), 157,158 Shaba Plateau, 109 Tourou Range, 67 Shaba Province (Zaire), 34,108,109 Transkei, 138,149,151,157-159 Shabeellaha Dhexe Region (Somalia), 90 Transvaal Province (South Afica), 25-27,39,40, Shabeellaha Hoose Region (Somalia), 90 137,139-141,145-147,149,151,153,158, Shashe River, 140 162,164 Shebelle, Wadi, 87,89-91 Tsau (Botswana), 149 Sherbro Island, 76 Tsavo National Park (Kenya), 123 Shewa Region (ECtopia), 86,92,93,96-99 Tswapong HIlls, 150 Shinyanga Region (Tanzania), 121,125 Tuli (Zimbabwe), 145,146 Shire Highlands, 148,156,160 Tuli River, 140 Shire VaUey,148,156 Sidamo Province (Ethiopia), 93,97,98 Uige Province (Angola), 155 Simien Region (Ethiopia), 86 Uitenhage (South Africa), 158 Singida Region (Tanzania), 121 Umkomaas VaUey,157 Sinoe County (Liberia), 72 Umtata (South Africa), 158 Sobat Province (Sudan), 86,88,95 Umtata River, 157 Sofala Province (Mozambique), 159-161 Umzimvubu Valley, 158 Sokoto (Nigeria), 31,65 Umzingwani River, 140 Sokoto State (Nigeria), 65 Upanda, Serra, 164 Southern Province (Zambia), 148,155,159 Upington (South Africa), 141 Southern Region (Malawi), 148 Upper Karroo, 145 Soutpansberg Mountains, 140 Upper Moa Basin, 73 Springbok (South Africa), 141,1-42 Usambara Mountains, 122,129,130 Springfontein (South Aftica), 151 Vaal River and Valley, 138, 151,153 Steinkop (South Africa), 142 Venda, 140 Stellenbosch (South Africa), 146 Viphya Massif, 160 Sterkstrom (South Africa), 139 Virginia (South Africa),138 Sudd, the, 95, 96 Volta Delta, 76 Indexof PlaceNames 191

Waanje River, 75 Windloek Mountains, 150 Wadi Hiwa, 87 Wadi Shebelie, 87,89-91 Yaounde (Cameroon), 112 Wallel (Etiiopia), 99 Welega Province (Ethiopia), 88,95,97,98 Zaire Province (Angola), 155,163 Wellington (South Africa), 146 Zaire River and Basin, 34, 72,73,105,111-13 Welo Province (Ethiopia), 34,86,89,92-94,97,98 Zambezi River and Valley, 148-50,155,156,159, Wepener (South Africa), 151 162, 163 West Lunga National Park (Zambia), 163 Zambezia Province (Mozambique), 156,160 Western Equatoria Province (Sudan), 93,96 Zambian Plateau, 160 Western Province (Zambia), 159, 164 Zanzibar, 125,127 White Nile Province (Sudan), 91 Zei 2diela (South Africa), 153 White Nile River, 88,94 Zimbabwean Mountains, 165 Windhoek (Namibia), 141,149 Zomba Plateau, 160 Legend for Land Cover Class Maps

DESERT WOODLAND LI] Desert Openwoodland Dry Sudanitn woodland GRASSLAND SudanlEthinpianwoodland and thicket HVeld grassland Sudanian woodland Hydromorphicgrassland Moist Sudanianwoodland Ethiopianmontane steppe Scasonal miombo Montanegrassland and heathland Wet miombo

WOODEDGRASSLAND HIGH WOODYBIOMASS MOSAICS

Semi-desertwooded grassland Evergreenwoodland mosaic Acacia wooded grassland Cultivationand forestwoodiand mosaic Plateau woodedgrassland Cultivationand forest regrowth mosaic Transitionalwooded grasland Guinean woodland Edaphicwooded grassland 1Highproductivity West African cultivation and forest Medium productivityWest African cultivationand romst SHRUBANDshrublanHighland cultivation mosaic VclIdshrubland Hill shrubland FOREST Bushy shrubland Mangrove Kalaharishrubland Evergreenforest Woodedshrubland Coastal and gallery forest Montane forest BUSHLANDryAcacTHICKETni s bushlandand thicket * Mesophiloushumid tropical forest ..Dry Acacia-Commipharabush_and and thicket Humid tropicalswamp forest Pynbac thicket Ombrophiloushumid tropical forest Moist Acacia-Commiphora bushland and thicket Sahel-SudanianAcacia woodedbushland Escarpmentwooded thicket aCoudcover

LOW WOODYBIOMASS MOSAICS Ae not mapped

Acacia woodlandmosaic CEastAfricanlow woodybiomass mosaic Tf /-StI /: :: 3,.-o~~ X :/D

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