126 Climate Change, Forests and Forest Management

ISSN 0258-6150 J, Climate change,change, : forests andand 126 J, forest managementmanagement i

An overviewoverview s/ss 38V

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Food and - AgdoultureAgriculture Organization - of _ the ,_. UnitedUnfted Nations

11i - o Climate change,change, forests andand forest managementmanagement

An overviewoverview

by William M.M. CieslaCiesla Forest Protection Officer FAO Forest ResourcesResources DivisionDivision

j ...... -..----- .. ,- -_'T~___ _ j t:;, .:;-~. ~ .. "_, , -' . .,. ,. ~, . '---~_~_l 1 ,,-, -" '.', I on LaLa DigueDigue i~_~: be particularlyparticularly )1irnate;limate change, andmd intensity of The designations employedemployed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concemingconcerning thethe legallegal statusstatus ofof any any country, country, territory,territory, citycity oror area or ofof itsits authorities,authorities, oror concemingconcerning the delimitationdelimitation of its frontiers oror boundaries.boundaries.

M-08 ISBN 92-5-103664-092-5-103664-0

All rights reserved.reserved. NoNo partpart ofof thisthis publicationpublication maymay bebe reproduced,reproduced, storedstored inin aa retrieval system, or transmittedtransmitted inin any formform oror byby any any means, means, electronic, electronic, mechanical,me.chanical, photocopying oror otherwise, without the prior permissionpermission of thethe copyright owner. Applications forfor such permission, withwith a statement of the purpose and extentextent ofof thethe reproduction,reproduction, shouldshould bebe addressedaddressed toto the the Director, Director, Publications Division, Food and AgdcultureAgriculture Organization ofof the UnitedUnited Nations, Viale delledells Terme di Caracalla,Caracalla, 00100 Rome,Rome,ltaly. Italy.

0© FAO FAO 19951995

Xi] ~= - I

FOREWORD

Changes in the world's climate, due to increases in the concentration ofof carboncarbon dioxidedioxide andand otherother greenhousegreenhouse gasesgases in thethe Earth's atmosphere, have thethe potentialpotential toto significantly affect forests and the practicepractice of forestry.forestry. The probabilityprobability ofof climateclimate changechange isis one ofof today'stoday's leading leading environmental environmental concerns.concerns. The issueissue is complex and filled with uncertainties.uncertainties. InformationInformation available on thethe subject is often confusingconfusing andand conflicting.

Climate is thethe keykey factorfactor whichwhich determinesdetermines thethe distributiondistribution ofof vegetationvegetation.. TheThe relationrelation ofof climate climate changechange toto thethe conservationconservation andand development ofof the world'sworld' s forestsforests isis therefore,therefore, anan importantimportant issueissue to consider.consider. ForestsForests cancan contributecontribute toto thethe greenhousegreenhouse effect, theythey can also be afaffectedfected byby. climate changechange and they offer opportunities to mitigatemitigate itsits effects.effects.

ItIt is important forfor forestersforesters toto havehave anan understandingunderstanding of the climate change iissuessue and itsits implications.implications . This document,document, which w hich isis presented in questionQuestion and answer format, isis designeddesigned to serveserve asas aa general referencereference onon thethe subjectsubject ofof climate change andand forests.forests. TheThe answers are basedbased onon thethe current world's literatureliterature includingincluding thethe most recent analysesanalyses by thethe IntergovernmentalIntergovernmental PanelPanel on ClimateClimate Change (IPCC).OPCC) . It isis hopedhoped that forestforest plannersplanners andand managersmanagers will find it useful in thethe preparationpreparation andand implementationimplementation of theirtheir programmes and in providing advice toto decisiondecision makers.makers.

J.J . P.P. Lanly,Lanly, DirectorDirector Forest Resources Division ForestryForestry Department ii

ACKNOWLEDGMENTS

The helpful and constructive commentscomments providedprovided by aa largelarge number of peoplepeople who reviewedreviewed thisthis documentdocument isis gratefullygratefully acknowledged.acknowledged.

External reviewsreviews were kindly provided by M. Fosberg,Fosberg, USDA Forest Service,Service, Washington DC, S. Brown, USUS EPA, Corvalis,Corvalis, Oregon, USA and M.M. HosnyHosny ElEl Lakany,Lakany, DesertDesert DevelopmentDevelopment Center,Center, AmericanAmerican University, Cairo,Cairo, Egypt.Egypt.

Internal (FAO) reviewsreviews were provided by W.G. Sombroek, Director,Director, Lands and Water Development Division and Chairman, InterdepartmentalInterdepartmental Working Group on Climate Change; R. Gommes, Coordinator, Agrometeorology Group,Group, RemoteRemote Sensing Centre; J.P. Lanly, Director,Director, ForestForest ResourcesResources Division;Division; C.C. Palmberg-Lerche, Palmberg-Lerche, Chief, Forest Resources DevelopmentDevelopment Service;Service; J.J. Ball, Senior Forest Plantations Officer, S.S. Braatz, Agroforestry andand LandLand Use Officer; P.P. Vantomme, Forest ManagementManagement Officer; D. Dykstra, Forest Harvesting Officer (Presently(Presently with CIFOR,CIFOR, Bogor, Indonesia);Indonesia); M. Trossero, WoodWood BasedBased EnergyEnergy Officer;Officer; C.C. Chandrasekharan,Chandrasekharan, Non-Non Wood ForestForest ProductsProducts Officer andand D.D. Suparmo,Suparmo, Advisor, TropicalTropical Forests Action Programme.Programme.

Special thanksthanks areare given to J.B.J.B. Harrington, formerlyformerly of thethe Petawawa National ForestryForestry InstituteInstitute,, Ontario, Canada, forfor hishis assistance with the technical editingediting ofof thethe manuscriptmanuscript andand F. Monti, FAO, Forestry Department Librarian, who assistedassisted in accessingaccessing the massive literature available on climateclimate change.change. iii

TABLE OFOF CONTENTSCONTENTS

FOREWORD ...... • ..•.. •...... •...... i

ACKNOWLEDGEMENTS ....•...... ii

TABLE OF CONTENTSCONTENTS ..•...... •..•.....•.. iii

LIST OF ACROACRONYMSNYMS ...... •...... ixix

LIST OF TABLES ...... •...... •... • . .• . ....•... xii

LIST OF BOXESBOXES ...... • . . . • ...... • . . . . . • .. xiii

LIST OFOF FIGURESFIGURES ...... •..•..•...... xiv

INTRODUCTIONINTRODUCTION ...... • . . . . . • . . • ...... • ...... 1

CHAPTER 11 - THE EARTH'S CLIMATE - A A DYNAMICDYNAMIC ENTITYENTITY 4

1. HOW ARE WEATHERWEA THER ANDAND CLIMA CLlMA TE TE DEFINED?DEFINED? .... . 4

2. TO WHAWHAT T EXTENT HAS THETHE EARTH'S CLIMACLlMA TETE CHANGED DURING THETHE COURSECOURSE OF GEOLOGICGEOLOGIC HISTORY? . . . .. 4

3. WHAWHAT T CHACHANGES NGES HA VEVE OCCURRED ININ THETHE EARTH'SEARTH'S CLlMACLIMA TETE SINCESINCE THE BEGINNING OF RECORDEDRECORDED HUMAN HISTORY? ...... 5

4. WHAT FACTORSFACTORS CAN CAUSECAUSE CHANGESCHANGES IN THETHE EARTH'SEARTH'S CLIMATE?CLIMA TE? ...... 9

CHAPTER 22 - THE GREENHOUSEGREENHOUSE EFFECTEFFECT ...... 151 5

5. WHAWHAT T IS THETHE "GREENHOUSE"GREENHOUSE EFFECT"EFFECT" AND AND HOWHOW DOESDOES ITIT INFLUENCE THE EARTH'S CLIMACLlMA TE?TE? ...... 15 iv

6. WHICH GASES ARE CONSIDERED TO TO BE BE GHGS GHGS AND AND WHA WHAT T ARE THETHE SOURCESSOURCES OFOF THESETHESE GASES? ...... 18

7. WHAWHAT T ISIS THETHE SIGNIFICANCESIGNIFICANCE OF HUMANHUMAN SOURCESSOURCES OFOF GHGS? ...... : ...... 22

B. DO ALL GHGSGHGS HA VEVE AN AN EQUAL EQUAL WARMING WARMING EFFECT? EFFECT? 2222

9. WHAWHAT T EVIDENCE EXISTSEXISTS TOTO SUPPORTSUPPORT THETHE IDEA IDEA THATHAT T GHG LEVELS IN THETHE AATMOSPHERE TMOSPHERE AREARE INCREASING? 2323

10. WHICH COUNTRIESCOUNTRIES PRESENTLYPRESENTLY MAKE THETHE GREAGREATEST TEST CONTRIBUTION TOTO ELEVAELEVA TED TED LEVELS LEVELS OF OF GHGS? GHGS? . ... 25

11 . HOW CANCAN AEROSOLSAEROSOLS COUNTERACTCOUNTERACT THE EFFECTSEFFECTS OF GHGS ...... 25

CHAPTER 3 - PREDICTED CHANGESCHANGES ININ THE EARTH'S CLIMATE ANDAND EXPECTED EXPECTED EFFECTSEFFECTS ...... 27

12. IN GENERAL,GENERAL, WHATWHAT AREARE THE THE PREDICTED PREDICTED EFFECTSEFFECTS OFOF INCREASED LEVELS LEVELS OF OF GHGSGHGS ON THETHE EARTH'SEARTH'S CLlMACLIMATE? TE? ...... 27

13. HOW AREARE CHANGESCHANGES ININ THE EARTH'SEARTH'S CL/MATECLIMATE PREDICTED? ...... 27

14. HOW RELIABLERELIABLE ARE PRESENTPRESENT PREDICTIONS OF CLIMACLlMA TETE CHANGE? ...... 30

15. WHAT CHACHANGES NGES IN CLIMACLIMATE TE AREARE PREDICTED WITHWITH A

DOUBLING OF CO,CO2 FROMFROM PRE-INDUSTRIALPRE-INDUSTRIAL REVOLUTION LEVELS? ...... 31

16. IS THETHE CLIMACLlMA TE OFOF SOMESOME REGIONSREGIONS OF THETHE WORLDWORLD EXPECTED TO CHACHANGE NGE TO A CREAGREA TER DEGREE THANTHAN OTHERS? ...... 33 v

17. WHAWHAT T CHACHANGES NGES ININ THETHE LEVELLEVEL OFOF THETHE OCEANSOCEANS AREARE EXPECTED DUE TO CLIMACL/MA TE CHANGE? ...... 34

1B. HOW WILLWILL PLANTS,PLANTS, INCLUDINGINCLUDING TREES, TREES, BEBE INFLUENCEDINFLUENCED BY CHANGESCHANGES IN THETHE LEVELSLEVELS OF GHGs IN THETHE EARTH'S ATMOSPHEREA TMOSPHERE AND RESULTANTRESUL TANT CHANGESCHANGES IN TEMPERA TURETURE AND AND PRECIPITAPRECIPITATION TlON ?1 ...... 34

19. HOW MIGHTMIGHT SOILSSOILS BEBE AFFECTEDAFFECTED BYBY CHANGESCHANGES ININ CLIMATE?CL/MA TE? ...... 37

20. IS THERETHERE ANYANY EVIDENCE EVIDENCE WHICHWHICH INDICA!NDICA TES THATTHA T CLIMACL/MA TE CHANGES MA YHA VEVE ALREADY OCCURRED OCCURRED DUE TO INCREASES IN GHGGHG LEVELS?LEVELS? ...... 38

CHAPTER 4 - THE GLOBAL CARBONCARBON CYCLECYCLE ...... 40

21. WHATWHA T PROCESSESPROCESSES EEXISTXIST FOR THETHE EXCHANGEEXCHANGE OFOF CARBON BETWEEN THE AATMOSPHERE, TMOSPHERE, THETHE OCEANS AND THE LAND? ...... 40

22. HOW ARE EXCHANGES OF CARBON EEXPRESSED?XPRESSED? . ... 41

23. WHATWHA T ISIS THETHE PRESENTPRESENT LEVELLEVEL OFOF CARBONCARBON EXCHANGEEXCHANGE BETWEEN THE AATMOSPHERE, TMOSPHERE, THETHE OCEANSOCEANS ANDAND THETHE LAND? ...... 45

CHAPTER 5 - TREES AND FORESTS AS SOURCES AND SINKSSINKS OFOF CARBON~RBON ...... 45

24. HOW MUCHMUCH OFOF THETHE EARTH'SEARTH'S SURFACE SURFACE ISIS PRESENTLY PRESENTL Y COVERED BYBY FORESTSFORESTS ANDAND OTHER WOODY VEGETAVEGETATION? TION? ...... 45

25. WHAWHAT T PROCESSESPROCESSES OCCUROCCUR ININ TREESTREES ANDAND FORESTSFORESTS WHICH CONTRIBUTE TO CHANGES IN LEVELS OF GHGSGHGS ININ THE EARTH'SEARTH'S ATMOSPHERE? ...... 45 vi

26. HOW MUCH CARBONCARBON IS RELEASEDRELEASED AND AND HOWHOW MUCHMUCH IS TAKEN UP ANNUALLANNUALLY Y BYBY FORESTS? FORESTS? ...... 47

27. DO DIFFERENTDIFFERENT FOREST ECOSYSTEMS VARYVA AY IN THEIRTHEIR

CAPACITY TOTO ABSORBABSORB AND STORESTORE CARBON?CARBON? ...... 47

2B. DO TREESTREES AND FORESTSFORESTS REMOVE CARBONCARBON FROMFROM THE EARTH'S ATMOSPHEREA TMOSPHERE AAT T DIFFERENTDIFFERENT RARATES TES DURING DIFFERENT STAGESSTAGES IN THEIR LIVES? ...... 49

29. WHICH HUMANHUMAN ACTIVITIESACTIVITIES ININ FORESTS AAND AID WOODLANDS CONTRIBUTECONTRIBUTE TO INCREASES IN THE LEVELSLEVELS OFOFGHGS? GHGS? ...... 53

30. WHAWHAT T ARE THETHE CURRENTCURRENT RARATES TES OF DEFORESTADEFORESTATION TlON ININ THE WORLD'S FORESTS?FORESTS? ...... 55

31 . HOW AREARE FORESTFOREST SOILSSOILS AFFECTEDAFFECTED BYBY DEFORESTATION?DEFORESTA TlON? ...... 56

CHAPTER 6 - POSSIBLE EFFECTSEFFECTS OF OF CLIMATECLIMATE CHANGECHANGE ONON FORESTS ...... 57

32. WHAWHAT T CHANGESCHANGES IN GROWTHGROWTH AND YIELDYIELD OFOF TREESTREES AND FORESTS CANCAN BE EXPECTED ASAS A RESULTRESUL T OFOF CLIMACLlMA TETE CHANGE? ...... 57

33. WHAWHAT T CHACHANGES NGES CAN BEBE EXPECTEDEXPECTED IN THETHE NATURALNA TURAL RANGES OF TREETREE SPECIES AND AND PLANT COMMUNITIESCOMMUNITIES DUE TO CLIMACLlMA TE CHANGE? ...... 58

34. WHAWHAT T ISIS THETHE LIKELIHOODLIKELIHOOD THATTHA T CLIMA CLlMA TE TE CHANGECHANGE COULD THREA TEN SOME SPECIESSPECIES OR PLANT COMMUNITIES WITH EXTINCTION? ...... 64

35. HOW MIGHTMIGHT CLIMACLlMA TE TE CHANGE INFLUENCEINFLUENCE THE INCIDENCE ANDAND INTENSITYINTENSITY OFOF WILDFIRES?WILDFIRES? ...... 66 vii

36. WHAWHAT TARE ARE THE THE EXPECTEDEXPECTED EFFECTS OF CLlMACLIMA TE CHACHANGE NGE ON FORESTFOREST HEALTHHEAL TH INCLUDINGINCLUDING SUSCEPTIBILITYSUSCEPTIBILITY TOTO PESTS ANDAND DISEASEDISEASE OROR DECLINE?DECLINE? ...... 67

CHAPTER 77 - HELPING FORESTSFORESTS ADAPT ADAPT TOTO CLIMATE CHANGE ...... 74

37. HOW CANCAN WEWE RESPOND RESPOND TOTO PREDICTED PREDICTED CLIMATECLlMA TE CHANGE? ...... 74

3B. DO NANATURAL TURAL PROCESSESPROCESSES EXISTEXIST WHICH CAN HELPHELP TREESTREES

AND FORESTSFORESTS ADAPT TOTO A CHANGINGCHANGING CLIMACLlMA TE?TE? . 75

39. HOW CAN FORESTFOREST MANAMANAGEMENT GEMENT HELP FORESTSFORESTS ADAPT ADAPT TO CLIMACLlMA TE CHANGE? ...... 75

40. WHAWHAT T CANCAN BEBE DONEDONE TOTO HELPHELP FORESTSFORESTS ADAPTADAPT TOTO INCREASEDINCREASED HAZARDSHAZARDS OF WILDFIRE ANDAND (OR) PEST ANDAND DISEASE OUTBREAKS WHICHWHICH COULDCOULD RESULTRESUL T FROMFROM CLIMACLlMA TE CHANGE? ...... 76

CHAPTER 8 - THE ROLE FORESTS ININ MITIGATING

THE EFFECTS OF CLIMATE CHANGECHANGE ...... 80 -

41. WHAWHAT T OPPORTUNITIESOPPORTUNITIES DODO FORESTSFORESTS ANDAND FORESTFOREST MANAGEMENT OFFER OFFER FOR MITIGAMITIGATING TlNG THETHE EFFECTSEFFECTS OF PREDICTED CL/MACLIMA TE CHANGE? ...... 80

42. WHAT FEAFEATURES TURES SHOULD CHARACTERIZECHARACTERIZE ACTIONSACTIONS TAKEN TOTO MITIGAMITIGA TETE POTENTIAL EFFECTSEFFECTS OF CLIMACLlMA TE CHANGE? ...... 81

43. WHAWHAT T ADDITIONALADDITIONAL RESEARCHRESEARCH IS NEEDEDNEEDED TO MOREMORE FULLFULLY Y UNDERSTANDUNDERSTAND THE POTENTIALPOTENTIAL EFFECTSEFFECTS OF CL/MACLIMA TE TE CHANGECHANGE ONON TREESTREES AND FORESTSFORESTS ANDAND FORESTRY ANDAND TOTO DEVELOP ADAPTAADAPTATION TION AND MITIGATIONMITlGA TlON TACTICS?TACTICS? ...... 81 viii

44. DO INTERNATIONAL AGREEMENTS EXISTEXIST WHICH ENCOURAGE DEVELOPMENTDEVELOPMENT AND AND PROTECTION OF FORESTS TO ENHANCE THEIR ABILITYABILITY TO MITIGA TE THE EFFECTS OF CLIMACLlMA TE CHANGE? ...... 83

45. HOWCANHOW CAN THETHE TROPICAL FORESTSACTlONFORESTS ACTION PROGRAMMEPROGRAMME ITFAP1(TFAP) ASSIST ININ DEVELOPING DEVELOPING FORESTFOREST SECTORSECTOR PROGRAMMES TO HELP MITIGAMITIGATE TE EFFECTS OFOF CLlMACLIMA TETE CHANGE? ...... 85

8A - REDUCING SOURCESSOURCES OFOF GREENHOUSEGREENHOUSE GASESGASES . . .. 86

46. WHAT ACTIONS CAN BEBE TAKENTAKEN TOTO REDUCEREDUCE THETHE CURRENT RARATES TES OF TROPICALTROPICAL DEFORESTATIONDEFORESTA TION ANDAND HOW MIGHTMIGHT THISTHIS AFFECTAFFECT EMISSIONSEMISSIONS OFOF GHGSGHGS FROM'FROM FORESTS? ...... 86

47. WHATWHA T CANSECAN BE DONE DONE TO TO REDUCE REDUCE THETHE FREQUENCYFREQUENCY AND SCALE OFOF FORESTSFORESTS ANDAND SAVANNASA VANNA WOODLANDWOODLAND CONSUMED BY BIOMASS BURNING?BURNING? ...... 87

48. HOW CANCAN INCREASINGINCREASING THETHE EFFICIENCYEFFICIENCY OFOF BURNINGBURNING FUEL WOOD AND OTHEROTHER BIOFUELS810FUELS REDUCE EMISSIONS OFOFGHGS? GHGS? ...... 90

49. HOW CAN USEUSE OFOF WOODWOOD ANDAND OTHEROTHER "BIOFUELS""BIOFUELS" IN PLACE OF FOSSIL FUELSFUELS HELPHELP REDUCE THE LEVELS OF GHGS IN THETHE ATMOSPHERE? ...... 92

50. HOW CANCAN MOREMORE EFFICIENT EFFICIENT TIMBERTIMBER HARVESTINGHARVESTING OPERA TlONS TIONS REDUCE REDUCE EMISSIONS EMISSIONS OF OF GHGSGHGS FROMFROM FORESTS? ...... 93

888B - MAINTAINING EXISTING EXISTING SINKSSINKS OF OF GREENHOUSE GREENHOUSE GASES ...... 96

51. HOW CANCAN MANAGEMENTMANAGEMENT ANDAND CONSERVATIONCONSERVATION OFOF NANATURAL TURAL FORESTSFORESTS ENHANCEENHANCE THEIRTHEIR CAPACITYCAPAC/TY TO FIX AND STORESTORE CARBON?CARBON? ...... 96 ixIx

52. WHAWHAT T USESUSES OFOF FORESTSFORESTS AND FORESTFOREST PRODUCTSPRODUCTS AREARE MOST DESIRABLEDESIRABLE FROM THE STANDPOINTSTANDPOINT OF LONGLONG TERM CARBON STORAGE? ...... 98

8C -• EXPANDING SINKSSINKS OFOF GREENHOUSEGREENHOUSE GASES.GASES . . . .. 99

53. HOW MUCH CARBONCARBON CANCAN BEBE FIXED IN WOODWOOD ANDAND SOIL SOIL ON A PERPER HECTAREHECTARE BASIS IN FORESTFOREST PLANTA TlONSTIONS IN BOREAL, TEMPERATETEMPERA TE AND TROPICALTROPICAL ZONES?ZONES? ...... 99

54. HOW MUCH ADDITIONAL AREA AREA OFOF FOREST PLANTAPLANTATIONS TIONS WOULD BEBE REQUIREDREQUIRED TOTO FULLYFULL Y OFFSETOFFSET PRESENTPRESENT ANNUAL INCREASESINCREASES ININ GHGGHG LEVELSLEVELS FROMFROM ALLALL SOURCES? .... , , , , , , , , , . , , . , , , , , , , , , , .. 100

55. TO WHAWHAT T EXTENT ARE SUITABLESUITABLE LANDSLANDS AAVAILABLE VAILABLE FOR AFFORESTATIONAFFORESTA TlON ANDAND REFORESTATION?REFORESTA TlON? WHERE ARE THEY? .. , , , , , , , , , , , , , . , , ' , , , , , , , , , , . " 102

56. OTHER THANTHAN AAVAILABILITY VAILABILlTY OF LAND,LAND, WHATWHA T OTHER OTHER CONSTRAINTS ARE THERE TO LARGE SCALESCALE AFFORESTATIONAFFORESTA TlON INITIATIVES?INITIA TlVES? " ... ,""",. 110505

57. WHAWHAT T ASSISTANCEASSISTANCE IS AVAILABLEA VAILABLE TO SUPPORTSUPPORT AFFORESTATIONAFFORESTA TlON ANDAND REFORESTA REFORESTA TION,TlON, PARTICULARLPARTlCULARL Y AT THE THE INTERNATIONALINTERNATIONAL LEVEL?LEVEL? , .. , .. " ,. , " 106

58. HOW CAN CAN AGROFORESTRYA GROFORESTRY AND URBANURBAN TREETREE PLANTlNGSPLANTINGS CONTRIBUTE TO THE MITIGATIONMITIGA TlON OF CLIMACLlMA TETE CHANGE? , , , , , ' , , , , , , , , , , , , , , , , , , , , , , ,. 107

59. IS THE PLANTINGPLANTING OF TREESTREES SOLELYSOLEL Y FORFOR CO,' C02 ABSORPTION A SOUNDSOUND POLICYPOLICY CONSIDERING CONSIDERING OTHEROTHER NEEDS FOR AAVAILABLE VAILABLE LAND? """"""" 112

60. WHATWHA T FOREST FOREST POLICIESPOLICIES SHOULD BE CONSIDERED AAT T THETHE COUNTRY LEVEL TO ADDRESS THETHE THREATTHREA T OFOF CLIMACLlMA TETE CHANGE? , ' . , ' , , , , , , , , . , , , . , , , , , , , . , , ,. 113

LITERATURE CITEDCITED " • . , •. . ,' . " " .. , . . " .,',.. 114 INDEX ., ' ,. ," ",",' . "."." ' . "' .'. ' ,.,' 123 xlxi

LISTLIST OF ACRONYMS AND ABBREVIATIONSABBREVIATIONS

C Carbon

CFC Chlorofluorocarbon

CH Methane

COCO,2 Carbon dioxide

ENSO El NinoNiño SouthernSouthern OscillationOnillation

FAO Food andand Agriculture Organization ofof the United Nations

FWD Foundation forfor Woodstove Dissemination.Dissemination.

FTTP Forests,Forests, Trees and PeoplePeople Programme

GCM General Circulation ModelModel

GEF Global Environmental Facility

GHG Greenhouse gasgas

Gt Gigatonne (109(10' tonnes)

GWP Global Warming PotentialPotential ha Hectare

IPCC IntergovernmentalIntergovernmental Panel on Climate ChangeChange

IPM IntegratedIntegrated pest managementmanagement

NGO Non Government OrganizationOrganization

NN2020 Nitrous oxideoxide

NO.NO,, Nitrogen oxidesoxides xii

Pg Petagramme (10" (10' tonnes)tonnes) ppbv Parts per billion by volumevolume ppmv Parts per million by volumevolume pptvpptv Parts per trillion by volumevolume tC Tonnes of carbon tC/ha Tonnes of carboncarbon perper hectarehectare

TCP Technical Cooperation ProgrammeProgramme (FAO)(FAO)

TFAP Tropical Forests Action ProgrammeProgramme

Tg Teragramme (10" (10' tonnes)tonnes)

UNCED United Nations ConferenceConference on EnvironmentEnvironment and Development

UNDP United Nations DevelopmentDevelopment ProgrammeProgramme

UNEP United Nations EnvironmentEnvironment ProgrammeProgramme

USDA United States Department of Agriculture

WB The World BankBank

WMO World MeteorologicalMeteorological OrganizationOrganization

WRI World ResourcesResources IInstitutenstitute xiii

LIST OFOF TABLESTABLES

Table 2.1 -- Direct global warming potentialspotentia Is of major greenhouse gasesgases for for aa 100100 year time horizonhorizon ...... 24

Table 44.1.1 - Estimated distribution of thethe globalglobal carboncarbon pool ...... 41

Table 5.1 - Land area covered byby forests andand otherother woodedwooded areas by regionregion ...... 46

Table 5.2 - Estimated annual rates of carbon exchange between thethe world'sworld's forests forests andand thethe atmosphereatmosphere . . . . . 48

Table 5.3 - Estimates of average above ground carbon/ha storedstored in various vegetation communitiescommunities...... 50

Table 5.4 - Estimated carbon densitiesdensities perper unitunit of forest areaarea inin

vegetationvegetation and soilssoils ofof thethe world's forests . .... 51

Table 8.1 -- Carbon fixationfixation rates for severalseveral tropicaltropical forestforest plantation speciesspecies ...... 99 xiv

LIST OF BOXESBOXES

Box 11.1 .1 - Historic droughts inin CaliforniaCalifornia andand PatagoniaPatagonia . . 8

Box 1.2-1.2 - Did thethe rising of thethe TibetanTibetan PlateauPlateau cool thethe world? ...... 13

Box 22.1.1 - What happenedhappened to atmospheric CO2CO, levelslevels in 1991? ...... 20

Box 4.14.1 - Peat bogs,bogs, a major carbon sink ...... 44

Box 5.1 - The role ofof forestforest plantationsplantations inin NewNew Zealand'sZealand's carbon balancebalance ...... 52

Box 6.16.1 - Will the future forestsforests ofof thethe worldworld be be drier?drier? 63

Box 6.2 - Decline of JuniperusJuniperus proceraprocer8 in Kenya -An example of aa regionalregional climateclimate change?change? ...... 73

Box 8.8.1 'I - Effects of treetree plantingplanting onon microclimatemicroclimate inin Nanjing,Nanjing, China ...... 111 xvXV

LIST OFOF FIGURESFIGURES

Figure 1.11.1 - A generalisedgeneralised history ofof changeschanges in temperature andand precipitation during geologicgeologic history.history. The curvescurves indicate departures fromfrom today'stoday's globalglobal means.means. Periods coldercolder thanthan today are shaded. DashedDashed lineslines indicate sparse data ...... 6

Figure 2.1 -- A simplifiedsimplified diagramdiagram of thethe greenhousegreenhouse effecteffect 16

Figure 2.2 -- Analysis of airair trapped in Antarctic iceice corescores showsshows that methanemethane andand carboncarbon dioxidedioxide concentrationsconcentrations were closely correlatedcorrelated with averageaverage temperaturestemperatures over the past 160 000000 yearsyears ...... 17

Figure 2.3 - Changes inin thethe levels ofof atmospheric COCO,2 over the past 250 yearsyears asas indicated by analysis of iceice corecore data from the Antarctic andand by atmospheric measurements atat Mauna Loa, Hawaii, USA,USA, sincesince 1958 ...... 24

Figure 3.1 - An exampleexample of aa predictionprediction ofof changechange inin globalglobal precIpitationprecipitation forfor winter (top)(top) andand springspring (bottom)(bottom) produced by the UKHI GCM. AreasAreas ofof decrease decrease areare stippled ...... 29

Figure 3.23.2 - Increases in in the the numbernumber of of tropical tropical storms, storms, which can damage manymany resourcesresources including including forests, areare a possible, but uncertainuncertain outcome ofof globalglobal climateclimate change ...... 33

Figure 44.1.1 - Schematic representation of the globalglobal carbon cycle showing movementmovement of carboncarbon betweenbetween carboncarbon sources and sinkssinks ...... 42

Figure 5.1 - An aerial view of a brush fire in the Sudan. RoughlyRoughly 750 millionmillion haha ofof savanna savanna vegetationvegetation areare burnedburned annually, resulting in a massive release of greenhouse gasesgases ...... 55 xvi

FigureFigure 6.16.1 - Pollen diagrams made fromfrom analysis of lakelake sediments in the Upper Peninsula ofof Michigan, USA. TheseThese datadata provideprovide cluesclues asas toto thethe composition of

forestsforests which occupied this area inin thethe past ... . 59

FigureFigure 6.26.2 - Holdridge Life-Zone Classification of vegetationvegetation types forfor presentpresent dayday (upper)(upper) andand underunder aa doubleddoubled

COCO22 scenarioscenario ofof temperature ...... 61

FigureFigure 6.3- Possible redistributionredistribution ofof loblolly pine,pine, PinusPin us taeda,taeda, inin thethe southeasternsoutheastern USA due toto a doublingdoubling of

atmospheric CO2CO 2 , • • • • • • • • • • • • • • . • • • •• 62

Figure 66.4.4 - Examples ofof species redistributionredistribution in high mountain regions duedue to aa 2°C2'C increaseincrease in meanmean annual.annual temperature:temperature: a = mountains ofof easterneastern Africa resulting in a relativelyrelatively smallsmall increaseincrease in area and b = highlands of Uganda resulting in a near disappearance ofof a high elevation vegetation zonezone ...... 62

Figure 6.5 -A forestforest ofof Ab/es Abies fraseri (raseri and and PiceaPicea rubensrubens straddlesstraddles the highesthighest ridgesridges in thethe BlackBlack Mountains of NorthNorth Carolina, USA.USA. Forests suchsuch as these wouldwould bebe unable toto shift theirtheir rangesranges upslopeupslope inin responseresponse to aa warming climateclimate ...... 65

Figure 6.6 - Insects such asas thethe pinepine caterpillar,caterpillar, DendrolimusDendrolimus punctatus, aa destructivedestructive defoliatordefoliator ofof tropicaltropical pinespines in Southeast Asia can undergo additional generations in warmer climatesclimates ...... 69

Figure 8.1 -- A foresterforester inin Mexico'sMexico's Yucatan Yucatan PeninsulaPeninsula assessassess forest fuels.fuels. Knowledge ofof fuel conditionsconditions is anan important factor inin planningplanning forestforest firefire managementmanagement programmes ...... 89 xviixvH

Figure 8.2 -- A load of fuelwoodfuel wood isis takentaken from aa forestforest plantationplantation to a villagevillage in Indonesia.Indonesia. RuralRural peoplepeople inin developingdeveloping countries rely heavily on fuelwood forfor cookingcooking andand heating. More efficient alternatives,alternatives, resultingresulting inin lower GHGGHG emissionsemissions areare availableavailable ...... 91

Figure 8.3 -- A comparisoncomparison ofof residualresidual carboncarbon storage storage betweenbetween conventional and reduced impact logginglogging in Malaysia ...... 95

Figure 8.4 -- InlA Vietnam, a womanwoman collectscollects resin in a pine plantation. Non-wood forest productsproducts cancan provideprovide economic incentives to managemanage and protect forests,forests, thus maintaining their capacity toto absorbabsorb andand storestore carbon..carbon ...... 97

Figure 8.5 -- Plantations of of fastfast growinggrowing trees, suchsuch asas thisthis plantation of PinusPinus radiataradiata in Chile, cancan absorbabsorb atmospheric CO, while providingproviding otherother benefitsbenefits 1011 01

Figure 8.68.6 - Shade trees,trees, such as these neems planted along the streets of Niamey,Niamey, thethe capitalcapital of Niger,Niger, lower temperatures and provide a more pleasant environment ...... 109 ClimateC//mate Change, Forests and Forest ManagementManagement 1

INTRODUCTION

The likelihood of global climate change and itsits possiblepossible effects,effects, includingincluding itsits effectseffects onon forests, isis one ofof the mostmost hotlyhotly debated environmentalenvironmental issuesissues of of the the decadedecade of of the the 90s.90s. WillWill the Earth's climate change in the future? TheThe answeranswer mustmust bebe an unqualified yes.yes. ThereThere havehave beenbeen alternatingalternating periodsperiods of cool and warmwarm climate throughout our planet's 3.5 billionbillion yearyear history. Therefore, therethere isis no reason toto expect that thethe Earth's present climate, duringduring whichwhich virtuallyvirtually all humanhuman development has taken place, will remainremain constant.

The more important and difficult questions questions are:are:

1. How will thethe Earth'sEarth's climateclimate change?change?

2. How will aa changingchanging climate affect thethe abilitiesabilities of humanhuman societiessocieties toto maintainmaintain andand enhanceenhance their quality of life?life?

3. What actions cancan bebe takentaken toto adapt to oror mitigate the effectseffects ofof climateclimate change?change?

Many scientists argue that the present period of relatively mild temperatures which havehave dominateddominated the Earth since the lastlast great continental ice sheets began toto recederecede somesome 1010 000000 years agoago isis aa shortshort interlude.interlude. TheyThey predictpredict that anotheranother iceice age will, onceonce again, cover largelarge areas of the Earth'sEarth's surface.surface.

A moremore near term concern is that the increasing evidence thatthat certain human activities,activities, suchsuch as burning of fossilfossil fuels,fuels, conversion ofof forests toto agriculturalagricultural landland atat unprecedentedunprecedented rates and other activitiesactivities areare causingcausing significant,significant .increases increases inin the levelslevels ofof carboncarbon dioxidedioxide (002)(CO,) andand otherother "greenhouse""greenhouse" gases inin thethe atmosphere.atmosphere. TheseThese changeschanges could lead to global warming at anan unprecedentedunprecedented raterate andand couldcould havehave seriousserious implications forfor agriculture,agriculture, fisheries,fisheries, forestry andand humanhuman development. Strategies forfor adapting toto and mitigating the 2 Climate Change,Change, Forests and Forest ManagementManagement effects ofof anan increasedincreased greenhouse effecteffect are presently being considered atat the national,national, regionalregional and international level.level.

There is much confusion and uncertainty associated with thethe climate change issue,issue. DuringDuring thethe pastpast decade,decade, many studies,studies, designed toto improve our capacity toto predict future climaticclimatic trends and thethe waysways inin whichwhich humanhuman societysociety mightmight bebe affectedaffected,, havehave been conductedconducted.. TheThe results of thesethese studies are often conflictingconflicting andand unclear.unclear.

The issues relatedrelated toto forestry are especially complexcomplex.. ForestsForests and human uses of forestsforests cancan contributecontribute toto increasesincreases inin atmospheric levelslevels ofof greenhousegreenhouse gases.gases. Forests are also affected byby changeschanges in climateclimate.. InIn addition,addition, trees and forests,forests,

because ofof their abilityability toto absorbabsorb CO2CO 2 and storestore carboncarbon inin woody tissue, offer anan opportunityopportunity to helphelp mitigatemitigate futurefuture climate change.change.

The complexitycomplexity of forests,forests, theirtheir relativelyrelatively longlong lifelife spanspan andand their multifaceted relationshiprelationship withwith climateclimate change change posepose many questions.questions. HowHow willwill forests forests bebe affectedaffected byby climate climate change?change? How cancan forestersforesters respond?respond? Can forest managementmanagement helphelp mitigate the effectseffects ofof climate climate change?change 7

The purpose ofof this paper isis toto provide a broad overviewoverview ofof the climate change issueissue asas itit relatesrelates toto forestry and forest managementmanagement.. ItIt alsoalso attempts toto provideprovide somesome insights as to how foresters cancan respondrespond to thethe challengeschallenges posed by possible futurefuture climate change. TheThe materialmaterial isis presentedpresented inin questionquestion and answer formform in eight chapters. TheseThese focus onon variousvarious aspects of thethe climateclimate changechange issueissue includingincluding thethe dynamicdynamic nature of clclimate,imate, the greenhousegreenhouse effect, effect, predictionspredictions ofof climateclimate change andand itsits effects, thethe globalglobal carboncarbon cycle,cycle, forestsforests asas sources andand sinkssinks ofof carbon,carbon, thethe effectseffects of predictedpredicted climate change on forests, strategies for helpinghelping' forestsforests adaptadapt toto climate change and thethe waysways inin whichwhich forests can mitigate the effects ofof climateclimate change.change. Climate Change, Forests and Forest Management 3

The material contained in this paperpaper isis designeddesigned for useuse byby field foresters,foresters, programmeprogramme managersmanagers and policy advisors at the national, regional and international level. 4 ClimateC//mate Change, Forests and Forest Management

Chapter 11 THE EARTH'S CLIMATE - A DYNAMIC ENTITYENTITY

1. HOW AREARE WEATHERWEA THER ANDAND CLIMACL/MA TE TE DEFINED?DEFINED?

Weather is the atmospheric condition prevailing in an area at a given time, resulting in heat or cold, clearness or cloudiness, dryness or moisture, wind oror calm.calm.

Climate, asas defined by the WorldWorld MeteorologicalMeteorological OrganizationOrganization (WMO).(WMO), is thethe "synthesis of weatherweather conditions inin aa given area as defined by long termterm statisticsstatistics of the variables of the state of the atmosphere". SeasonalSeasonal changeschanges such as the transition from winterwinter to to spring, spring, summersummer andand autumnautumn inin temperate zones and from wet toto drydry inin thethe tropicstropics areare also part of climate.

Climate is a keykey factor whichwhich determinesdetermines the distributiondistribution ofof plants and animals andand inin thethe formationformation ofof soils through the weathering of geologicalgeological materials and thethe decomposition or preservation of organic matter.

2. TO WHATWHA T EXTENTEXTENT HASHAS THETHE EARTH'SEARTH'S CLIMACL/MA TE TE CHANGED DURING THETHE COURSECOURSE OFOF GEOLOGICGEOLOGIC HISTORY?

While the Earth'sEarth's climateclimate hashas beenbeen sufficientlysufficiently stablestable toto support life forfor millionsmillions ofof years,years, climateclimate isis dynamicdynamic andand subject to change.change. ThereThere isis ampleample evidenceevidence from thethe fossilfossil record and other indicators such asas treetree ringring widths,widths, growth rates ofof marinemarine organismsorganisms andand types of vegetation,vegetation, asas indicated by fossilfossil pollen,pollen, that thethe Earth'sEarth's climateclimate hashas beenbeen characterized by periods of warm and cool weather everever since its existenceexistence (Fig(Fig 1.1).1.1). For example, overover 230 millionmillion yearsyears ago, duringduring thethe latterlatter partpart ofof the the Palaeozoic Palaeozoic Era,Era, glaciersglaciers covered much of today'stoday's tropics.tropics. During muchmuch of thethe Mesozoic Era, however,however, when dinosaurs and other reptilesreptiles Climate Change, Forests and ForestForest ManagementManagement 5 dominated thethe Earth (1(180 80 million to 6565 millionmillion yearsyears ago),ago), temperatures were much warmer thanthan theythey areare today.today.

Over the pastpast millionmillion years,years, thethe Earth'sEarth's climateclimate hashas beenbeen characterized by long periods of cold weather whenwhen continental glaciersglaciers coveredcovered largelarge areas.areas. EachEach ofof thesethese lastedlasted from 8080 000000 toto 100 100 000 000 years years and and were were interspersed interspersed byby shorter periods of warmer weather which ranged from 10 000 to 1515 000000 yearsyears each.each. AtAt the the peak peak ofof the the last last glacial glacial period,period, some 18 000 yearsyears ago, ocean levels werewere 130 m lower than they areare today. TheThe Bahamas Bahamas werewere aa substantialsubstantial landland massmass during that timetime andand thethe SahelSahel region of AfricaAfrica waswas aa desert.desert. The continental glaciers began toto retreat about 10 000 yearsyears ago. Some 6 000 yearsyears ago,ago, asas thethe glaciersglaciers werewere stillstill in retreat, the EarthEarth enteredentered aa periodperiod duringduring whichwhich averageaverage temperatures were about whatwhat they are todaytoday butbut withwith slightly warmer summers and colder winters. RainfallRainfall increased increased overover the AfricanAfrican SahelSahel and Lake Chad roserose toto more thanthan 40 mm above its presentpresent level.level. Human culturescultures inin AfricaAfrica werewere considerably more advanced than thosethose inin Europe.Europe. As the glacial ice sheets continued to retreatretreat northvvard,north""ard, thethe SahelSahel again became aa regionregion ofof marginal rainfall,rainfall, withwith itsits northernnorthern regions invaded byby thethe SaharaSahara desert.desert.

Many scientists believe thatthat the present period of relatively mild temperatures which we enjoyenjoy todaytoday willwill eventuallyeventually givegive way toto anotheranother iceice ageage (Easterling(Easterling 1990, HarringtonHarrington 1987).1987).

3.3, WHAWHAT T CHANGESCHANGES HA VE OCCURRED IN IN THETHE EARTH'SEARTH'S CL/MACLIMA TE TE SINCE THETHE BEGINNINGBEGINNING OFOF RECORDED RECORDED HUMAN HISTORY?HISTORY?

Historical recordsrecords showshow thatthat overover thethe past 1 100 years,years, thethe Earth hashas experiencedexperienced swingsswings inin climate,climate, at leastleast onon aa regional basis, which have been sufficientlysufficiently stablestable andand have persisted long enoughenough toto bebe consideredconsidered clirnatecl imate changes changes (Easterling(Easterling 1990). 6 ClimateC//mate Change, Forests and Forest Management

MEAN GLOBAL MEAN GLOBAL TEMTEMPERATUREPERATURE PRECIPITATIONPRECIPITATION present present cod warm dry wet

Quaternary 1.8 Pliocene I 4-ien Miocene I Jl ::j Oligocene » ::0 Eocene -< Palaeocene 65

CretacCretaceouseous A~ (f) o JuraJurassicssic 2N ~ TriassicTri assic 225 m Permian ~ Carboniferous :Ii r- Devonian » ~ 411 en >- 0 SilunanSilurian N 4INS ' 0 OrdoviciaOrdoviciann 0

Cambrian 570570

1000 .___I____ "--.1

1l ....i' ::0 2000 [lJ » -,, ;:: X CD X '!l » 3000 1. 1 z I 1

44000000

44600600

Figure 1.11.1 - A A generalisedgeneralised history of changeschanges inin temperaturetemperature andand precipitation during geologic history. TheThe curvescurves indicateindicate departures from today'stoday's globalglobal means.means. PeriodsPeriods coldercolder thanthan todaytoday are are shaded.shaded. Dashed lineslines indicateindicate sparse datadata (Source(Source:: GoodessGoodess etet aalI (1992). Climate Change, ForestsForests andand ForestForest ManagementManagement 7

During the periodperiod inin EuropeanEuropean history knownknown asas thethe MiddleMiddle Ages, a warm climate, lasting from about A.D. 900 to A.D.A.D. 12001 200 dominated mostmost ofof EuropeEurope andand was knownknown asas thethe Medieval Optimum. ThisThis periodperiod allowedallowed human habitation to extend into regionsregions which wouldwould bebe considered climatically tootoo harsh today. DuringDuring thethe MedievalMedieval Optimum,Optimum, oatsoats andand barleybarley were growngrown inin IcelandIceland andand vineyardsvineyards flourishedflourished inin southernsouthern England. CanadianCanadian forests extendedextended northnorth forfor aa considerableconsiderable distance from wherewhere they areare today,today, agriculturalagricultural settlementssettlements flourished inin thethe northernnorthern highlandshighlands ofof ScotlandScotland andand aa VikingViking colony waswas establishedestablished inin Greenland.Greenland.

The Medieval Optimum endedended duringduring thethe 13th centurycentury andand was replacedreplaced byby 600 years of pronouncedpronounced cooling.cooling. AsAs thethe cooling intensified, thisthis periodperiod becamebecame known as the Little Ice Age.Age. SnowSnow and and iceice covercover werewere more more extensiveextensive duringduring thisthis period than atat anyany timetime sincesince thethe PleistocenePleistocene PeriodPeriod and its extensive glaciers. VikingViking coloniescolonies whichwhich existed existed inin GreenlandGreenland between AD 985 and 1500 died outout (McGovern(McGovern 1981)1981).. NorthNorth American forests retreatedretreated southwardsouthward andand canalscanals in NorthernNorthern Europe werewere often frozenfrozen throughout the winter,winter, bringingbringing water transportationtransportation to aa halt.halt.

By the timetime thethe LittleLittle IceIce AgeAge lessenedlessened itsits gripgrip onon Europe'sEurope's climate duringduring thethe mid-1800s,mid-1800s, variousvarious climaticclimatic parameters parameters such asas temperaturetemperature and 'precipitation werewere beginningbeginning to bebe routinely recordedrecorded'. 1. These data showshow that byby the end of thethe 19th century,century, aa warmingwarming trendtrend beganbegan to occuroccur inin bothboth thethe northern andand southernsouthern hemispheres.hemispheres. This trend reachedreached anan initial peakpeak duringduring thethe 1930's.1930's. In thethe yearsyears immediatelyimmediately following, globalglobal temperaturestemperatures cooledcooled slightlyslightly beforebefore resumingresuming their upwardupward trend.trend. TheThe coolingcooling trendtrend waswas more more pronouncedpronounced in thethe northernnorthern hemisphere.hemisphere.

~ Temperature and preprecipitationcipitation recordsrecords forfor partsparts ofof Europe Europe areare availableavailable as8S far backbeck asas thethe 12th12th century.century_ A summarysummary of wetwet andend drydry summerssummers inin northernnorthern Germany is given by Finck (1985). 8 Climate Change, Forests andand Forest Management

Box 1.11.1 Historic droughtsdroughts inin CaliforniaCalifornia andand Patagonia.

While EuropeEurope was baskingbasking in thethe MedievalMedieval Optimurn,Optimum, other parts of the world apparently were ·sufferingsuffering fromfrom prolongedprolonged drought. AccordingAccording toto a a recentlyrecently completed study, whichwhich includedincluded analysisanalysis of ancientancient submerged tree stumps, the areaarea of present day California, USA, was affectedaffected by two longlong and severe droughts during most ofof thethe Medieval Optimum. TheseThese werewere separatedseparated by aa period of unusualunusual wetnesswetness whichwhich lasted lessless thanthan aa century.century. The first ofof these droughts lasted forfor more thanthan two centuries. The secondsecond persisted for overover 140 years.years. There is evidenceevidence from thethe Patagonia RegionRegion of of SouthSouth AmericaAmerica thatthat it also was affectedaffected byby droughtdrought duringduring thisthis timetime period.period.

The droughts inin CaliforniaCalifornia maymay havehave beenbeen thethe result of a northward shift of summertime storms.

California isis presently home toto 30 millionmillion people. Consequent/y,Consequently, a present dayday drought of thisthis magnitude would be devastating (Stine 1994).1994). ClimateC//mate ChangeChange,, Forests and ForestForest ManagementManagement 9

The world climatic recordrecord forfor thethe pastpast twotwo decades decades indicatesindicates that globalglobal surfacesurface airair temperaturestemperatures havehave increasedincreased above the 1930 maximums.maximums. ThisThis warmingwarming trendtrend extendsextends to bothboth thethe Southern and Northern HemisphereHemisphere (Couglan and Nyenzi 1990) and has resulted in a globalglobal meanmean surfacesurface temperaturetemperature increase of about 0.45°0.450 CC sincesince the middlemiddle of thethe lastlast century.century.

4. WHAWHAT T FACTORSFACTORS CANCAN CAUSECAUSE CHACHANGES NGES IN THETHE EARTH'S CLIMACL/MA TE? TE?

Changes inin thethe Earth's temperature andand associated changes in climate have complexcomplex causes.causes. TheseThese can be classified into the following categories:categories:

Astronomical factorsfactors - such asas changeschanges inin solar activity, variationsvariations in thethe eccentricityeccentricity ofof thethe Earth'sEarth's orbit around the sunsun,, changeschanges in the tilt ofof thethe Earth'sEarth's axis (obliquity)(obliquity) precession ofof the Earth'sEarth's axisaxis andand collisions with asteroidsasteroids oror comets.comets.

Geological factorsfactors - such as continental drift, changeschanges in the topographytopography of the oceanocean floor, volcanic eruptions, mountain building, erosion and weatheringweathering of rock.

Oceanic FactorsFactors -- suchsuch asas thethe ElEl NiiioNiño effect,effect, changeschanges in ocean circulation, seasea level changes, iceice formation, phytoplankton bloomsblooms and dimethysulphidedimethysulphide production.production.

Land SurfaceSurface Factors -including the effect of vegetation onon surfacesurface albedoalbedo (the whiteness oror degreedegree of reflectionreflection ofof incidentincident lightlight fromfrom anan object),object). andand evapo-transpiration, open waterwater effects including irrigation andand dust.dust. 10 Climate Change, Forests and Forest Management

AAtmospheric tmospheric FactorsFactors -- such as thethe effecteffect of greenhouse gases, sulphursulphur dioxidedioxide andand air air pollutants, pollutants, cloud cloud effects effects and interactions between thethe air,air, the land and the sea.

Some examplesexamples of of thethe influence ofof these factors onon globalglobal climate are described in the following paragraphs.paragraphs.

Changes inin solarsolar activity, activity, such as thethe frequencyfrequency andand intensityintensity of sunspots, or the gradualgradual warming of the sun as its supply of hydrogenhydrogen isis consumed,consumed, areare believedbelieved to havehave significantsignificant effects on climate.climate. TheThe virtualvirtual cessationcessation of sunspot activityactivity for aboutabout 70-8070-80 yearsyears inin thethe 17th17th century,century, forfor example,example, coincides with the peakpeak of the LittleLittle IceIce Age, a period when a series of disastrous harvests inin EuropeEurope resulted in decades of hardship and socialsocial unrest.unrest. The warmingwarming trend, whichwhich followed the LittleLittle IceIce Age,Age, coincidedcoincided withwith aa resumptionresumption inin sunspot activity. TheThe recent recent period period ofof warmerwarmer temperatures,temperatures, is associated withwith exceptionallyexceptionally strong sunspotsunspot activityactivity beginning in the late 1980s1980s (Harrington(Harrington 1987,1987 ,Windelius Windelius andand Tucker 1990). HoweverHowever the the measured measured increase increase inin solarsolar energy received byby the EarthEarth during peaks ofof sunspot activity doesdoes not appearappear to bebe sufficientsufficient toto cause cause significantsignificant changeschanges inin climate.

In rarerare instances,instances, large asteroidsasteroids havehave collidedcollided withwith thethe Earth.Earth. Such aa collision cancan have aa number ofof catastrophic effects, including thethe developmentdevelopment of of a a layerlayer of of finefine dustdust in thethe atmosphere whichwhich reduces thethe amountamount ofof solar energyenergy reaching the Earth's surfacesurface.. This can causecause reducedreduced temperatures and lightlight intensities.intensities. Some scientists believebelieve that thethe collisioncollision ofof anan asteroidasteroid of aboutabout 1010 kmkm inin diameterdiameter with thethe Earth,Earth, somesome 6565 millionmillion yearsyears ago,ago, resultedresulted in thethe drastic cooling that broughtbrought anan endend toto thethe ageage ofof dinosaurs.dinosaurs. Approximately one half of thethe generagenera ofof plantsplants andand animalsanimals living during this periodperiod becamebecame extinct (Harrington(Harrington 1987).1987).

The Milankovitch theorytheory of of ice ice ageage occurrenceoccurrence isis basedbased on long term variation inin solarsolar radiationradiation receivedreceived at thethe polarpolar latitudeslatitudes Climate Change, Forests and ForestForest ManagementManagement 11 during certain seasonsseasons of thethe year.year. These are caused byby changes in thethe eccentricity ofof thethe Earth'sEarth's orbitorbit aroundaround thethe sun,sun, which variesvaries between the limits of 0 and 0.06 withwith an an averageaverage period ofof 93 000 years;years; the angleangle of tilt ofof thethe Earth'sEarth's axis,axis, which variesvaries between 22.1 andand 24.5° withwith anan averageaverage of 41 000000 yearsyears andand thethe precessionprecession of the Earth'sEarth's axis,axis, whichwhich varies with anan averageaverage periodperiod of 2121 000000 years years (Weertman(Weertman 1976).

Volcanoes occasionally erupterupt withwith such violence that largelarge quantities of dustdust andand gasgas areare projected high intointo thethe atmosphere. Particles which reachreach thethe stratospherestratosphere maymay persist for several yearsyears.. TheyThey causecause cooler temperatures by rreflectingeflecting solarsolar radiation.radiation. The Little IceIce AgeAge waswas aa periodperiod characterized byby frequentfrequent volcanicvolcanic activityactivity when compared to thethe present century. TheThe eruptioneruption ofof thethe IndonesianIndonesian volcano,volcano, Tambora inin 1815, the largest eruption in recordedrecorded history,history, was followed byby aa periodperiod ofof coolcool weatherweather inin portionsportions ofof Europe, Europe, North America and possibly otherother partsparts ofof the world, knownknown as "The Year WithoutWithout Summer." ThisThis resultedresulted in a failure of the corn cropcrop inin portionsportions ofof thethe UnitedUnited StatesStates andand massivemassive crop failures in western EuropeEurope (Stommel andand StommelStommel 1983). In Ghent, Belgium, forfor example, thethe summersummer ofof 1816 was thethe coldest recorded between the years 1753 and 1960 (Gommes(Gommes 1980). VolcanicVolcanic emissions emissions duedue toto thethe eruptioneruption ofof El El ChichónChich6n in Mexico inin 19821982 and and PinatuboPinatubo inin thethe PhilippinesPhilippines in 1991 alsoalso caused a slight cooling effect.

The ocean plays an essentialessential rolerole inin thethe globalglobal climateclimate systemsystem.. Over half of the solarsolar radiation reachingreaching the Earth'sEarth's surfacesurface isis first absorbed by thethe ocean, wherewhere it isis stored and redistributed by oceanocean currents beforebefore escaping escaping intointo thethe atmosphere. TheThe oceanocean currents areare driven by the exchangeexchange of momentum,momentum, heat and waterwater betweenbetween thethe oceanocean andand thethe atmosphere (Cubasch and Cess 1990).1990).

An oceanocean current which is knownknown toto havehave aa significantsignificant influence on globalglobal climate isis knownknown asas ElEl NiñoNilio (Spanish(Spanish forfor 12 ClimateClima te ChangeChange,, ForestsForests andand ForestForest Management

Christ Child).Child). El NinoNiño isis a warmwarm ocean currentcurrent thatthat typically appears alongalong thethe coast of westernwestern SouthSouth AmericaAmerica aroundaround Christmas and lastslasts forfor several months.months. An ElEl NinoNiño is initiatedinitiated by thethe SouthernSouthern OscillationOscillation (ENSO),(ENSO), whichwhich arises fromfrom the gradient between aa low pressurepressure system which lies overover portions of IndonesiaIndonesia and Malaysia and a highhigh pressurepressure systemsystem in the South Pacific. WhenWhen thethe difference in pressure betweenbetween these twotwo systemssystems isis reduced,reduced, the westward tradetrade windswinds areare weakened, causing aa warmingwarming ofof the ocean surface off thethe coast of Peru.Peru. ThisThis causescauses the low pressurepressure systemsystem toto shiftshift eastward and leads to aa decrease in rainfallrainfall over Malaysia and Indonesia andand increasedincreased precipitation precipitation over over the the westwest coastcoast of Central and SouthSouth America. AA particularlyparticularly severe severe ENSO ENSO during 1982-83 causedcaused a severesevere drought on the islandisland ofof BorneoBorneo resulting in thethe most extensive forest fires in rrecordedecorded historyhistory.. Approximately 3.5 millionmillion haha ofof primaryprimary andand secondarysecondary rainrain forests inin EastEast Kalimantan, IndonesiaIndonesia were burned as a result of thesethese firesfires (Goldammer(Goldammer andand SeibertSeibert 1990).1990). This samesame ENSO resultedresulted inin severesevere stormsstorms and massive flooding alongalong thethe west coast of South America. ENSOENSO events are knownknown toto influenceinfluence weatherweather woworldwide.rldwide. ThisThis isis thethe principalprincipal globalglobal scale environmental factorfactor which affects AtlanticAtlantic seasonal seasonal hurricane activityactivity.. HurricanesHurricanes areare suppressed duringduring seasons when warm equatorial eastern and central Pacific water temperaturestemperatures occur.occur. ActivityActivity is is enhancedenhanced during seasons withwith cold water climates (Grey 1993).1993). ThereThere is also evidence thatthat ENSOs areare linked linked to to belowbelow average rainfallrainfall inin southernsouthern Africa (Cane(Cane etet alal 1994).

The oceans also containcontain chemical and biologicalbiological mechanismsmechanisms which areare importantimportant inin controllingcontrolling CO2.CO,. CO,CO2 isis transferred from thethe atmosphereatmosphere intointo the oceanocean by differencesdifferences in thethe partial pressure ofof CO,CO2 inin thethe oceanocean andand thethe lowestlowest layers of the atmosphere.atmosphere. The oceansoceans alsoalso containcontain phytoplanktonphytoplankton which convertconvert dissolveddissolved CO2CO, into particulateparticulate carboncarbon whichwhich sinks into deep water (Cubasch(Cubasch and Cess 1990). Climate Change, Forests and ForestForest ManagementManagement 13

Box 1.21.2 Did the risingrising ofof thethe TibetanTibetan Plateau coolcool the world?

The Tibetan Plateau, which lies between the Himalayas inin the southsouth andand thethe KunlunKunlun ivlountainsMountains in the northnorth isis believedbelieved to havehave been causedcaused byby continental continental driftdrift endingending withwith India andand AsiaAsia colliding.colliding. TheThe PlateauPlateau covers about 2.22.2 millionmillion squaresquare kilometreskilometres and is equivalent to to 0.4%0.4% of thethe Earth'sEarth's totaltotal surface area. Average elevationelevation isis 5 kilometres above seasea level.level. It hashas beenbeen suggested that that thethe uplift ofof thethe plateauplateau created patterns of airair circulationcirculation whichwhich bring water ladenladen air off thethe IndianIndian OceanOcean in summer and deliver monsoonal rains to the Indian subcontinent. Atmospheric carboncarbon dioxide is dissolveddissolved in thethe torrentialtorrential rains,rains, forming a weakweak solutionsolution ofof carboniccarbonic acidacid which erodeserodes the plateau'splateau's bedrockbedrock and is delivered to thethe oceanocean asas bicarbonates. bicarbonates. This processprocess isis believedbelieved to havehave removedremoved large quantities of carboncarbon dioxide fromfrom thethe Earth's atmosphereatmosphere resultingresulting inin aa globalglobal cooling effect (Patterson(Patterson 1993).1993). 14 ClimateC//mate Change, ForestsForests andand ForestForest ManagementManagement

The average temperaturetemperature ofof the Earth isis presentlypresently 15·C.15°C. This is largelylargely due toto thethe effectseffects of radiativeradiative oror "greenhouse""greenhouse" gasesgases which areare presentpresent in the atmosphere. WithoutWithout thesethese gases,gases, the Earth'sEarth's averageaverage temperaturetemperature would bebe -18°C.-1S·C. This isis equivalent to the temperaturetemperature ofof thethe surfacesurface ofof thethe moonmoon andand life,life, as we know it, would not bebe possible. Most of the short wavelength radiation which the EarthEarth receives fromfrom the sun passes throughthrough these gases and warms the Earth'sEarth's surface.surface. The surface, in turn, emitsemits longlong wavewave thermalthermal radiationradiation backback to thethe atmosphere.atmosphere. ThisThis is is absorbed absorbed byby thethe greenhousegreenhouse gasesgases and heats the atmosphere. TheThe atmosphereatmosphere emits long wave . radiation into space andand downwarddownward toto further heat thethe Earth's surface (See question 5 for aa moremore detaileddetailed explanation). Climate Change,Change. ForestsForests andand Forest Forest ManagementManagement 15

Chapter 2 THE GREENHOUSEGREENHOUSE EFFECTEFFECT

5. WHAWHAT T ISIS THETHE "GREENHOUSE"GREENHOUSE EFFECT"EFFECT" ANDAND HOW DOES IT INFLUENCEINFLUENCE THETHE EAEARTH'S i TH'S CLIMACLlMA TE? TE7

The greenhouse effect effect isis the retention of heat in thethe lowerlower atmosphere due to absorptionabsorption andand re-radiationre-radiation by cloudsclouds andand certain gases.gases. TheThe EarthEarth receivesreceives its energyenergy fromfrom thethe sunsun asas solar radiation.radiation. Short-wave solarsolar (visible)(visible) radiationradiation receivedreceived from thethe sunsun passespasses through the atmosphere with littlelittle oror nono interference and warms thethe Earth'sEarth's surface.surface. Long-wave thermal radiation emitted byby thethe warmedwarmed surfacesurface ofof thethe EarthEarth is partiallypartially absorbedabsorbed by aa numbernumber of tracetrace oror "greenhouse""greenhouse" gases (GHGs)(GHGs).. TheseThese gases occur in small amounts in the atmosphere and reflect the longlong wavewave thermalthermal radiationradiation inin allall directions.directions. Some of thethe radiationradiation isis directeddirected downwardsdownwards toward thethe Earth'sEarth's surfacesurface (Fig(Fig 2.1).

The amount ofof GHGsGHGs inin thethe atmosphereatmosphere cancan influenceinfluence globalglobal temperatures. IfIf these gases were to increase,increase, temperaturestemperatures could rise.rise. If theythey werewere toto decrease, decrease, globalglobal temperaturestemperatures would cool.cool.

The greenhousegreenhouse effecteffect isis a wellwell understoodunderstood phenomenonphenomenon based onon establishedestablished scientificscientific principles. TheThe Earth'sEarth's averageaverage surface temperature, for example,example, is warmerwarmer byby aboutabout 33°C33°C than it wouldwould bebe withoutwithout thethe presence presence ofof these these gases.gases. Satellite observations of the radiation emitted from the Earth's surface and through the atmosphere confirmconfirm thethe effectseffects of greenhouse gases.gases. TheThe compositioncomposition of thethe atmospheresatmospheres of Venus, the EarthEarth and Mars are quitequite differentdifferent but theirtheir surfacesurface temperatures are in general agreement withwith the principlesprinciples ofof greenhouse effecteffect.. Finally, measurements fromfrom iceice corescores going back 160160000 000 yearsyears showshow thatthat thethe Earth'sEarth's temperaturetemperature closely paralleled thethe amount of carbon dioxide and methane, 16 Climate Change,Change, Forests and ForesForestt ManagementManagement

Some solarsolar radiation is reflected by thethe earthearth and the atmosphereatmosphere

ome of the infra-red radiation is absorbed and re-emitted by the greenhouse gases. The effect of this is t warm the surface and the lower atmosphere

Most radiatradiationion is absorbedabsorbed Infra-redInfra-red radiationradiation byby the earth's surfacesu rface EARTH is emiemittedtted fromfrom and wawarmsrms it. the earth'searth's surface

Figure 22.1.1 - A simplifiedsimplified diagramdiagram ofof thethe greenhousegreenhouse effecteffect (Source:(Source: Houghton 1991)1991).. two of the moremore importantimportant greenhouse gases in the atmosphere (Fig(Fig 2.2).2.2). TheThe changeschanges in the amounts of these gases maymay bebe some,some, butbut notnot all, of the reason for the largelarge (5-(5- 7°C) globalglobal temperaturetemperature differencesdifferences between the iceice agesages andand the interglacialinterglacial periodsperiods (Houghton(Houghton 1991).1991). Recent studiesstudies indicate that thethe temperaturestemperatures andand GHGsGHGs areare soso closelyclosely correlated thatthat itit is difficult toto determinedetermine whichwhich isis thethe causecause and which is the effect. ClimateC//mate Change, ForestsFDrests and ForestForest ManagementManagement 17

UJ a: 2 ::J ~ t- U 0 <{ 0 a: --2 UJ UJ 0.. Cl - 4 ~ Z UJ <{ - 6 t- I --' U -8 -->'> <{ 700 E U - 10 o_a. 0 o_a. --' W z METHANE 6006 00 z~ 0is <{ It H11'>' E UJa.w a 300 o~a 300 - 300 XZ-5- z 280 CARBON DIOXIDE 280 go0 260 - 260 oi=H z <<{ 240 240 o F_a:I 220 222020 ocot-ca z a: Z 200 - 200 <{UJ

Figure 2.22.2 -- AnalysisAnalysis ofof airair trappedtrapped inin AntarcticAntarctic ice corescores showsshows thatthat methane and carboncarbon dioxide concentrationsconcentrations were closelyclosely correlatedcorrelated with averageaverage temperatures overover thethe pastpast 160 000 yearsyears (Watson et al 1990). 18 Climate Change, Forests and Forest Management

6. WHICH GASES ARE CONSIDERED TOTO BEBE GHGSGHGS AND AND WHAWHAT T AREARE THE THE SOURCESSOURCES OFOF THESETHESE GASES?

Greenhouse gases (GHGs)(GHGs) presentpresent. inin thethe Earth's atmosphere include water vapourvapour (H20),(H 20), carboncarbon dioxidedioxide (CO2),(C02 1. methane

(CH.1.(CH4), nitrousnitrous oxideoxide (N(N20),20), nitrogen oxides (NO.),(NO,1. ozone (03),(03 ), carbon monoxide, (CO) andand chlorofluorocarbonschlorofluorocarbons (CFC).(CFC). The concentrations ofof thesethese gasesgases in the Earth's atmosphere have changed over geologicalgeological time scales.scales. Since the lastlast glacialglacial period, the levels of these gases remainedremained relativelyrelatively constant.constant. As agriculture and animal husbandry developed,developed, the the world'sworld's population increased andand human societysociety becamebecame moremore industrialized,industrialized, thethe levels of somesome ofof thesethese gasesgases increasedincreased significantly (Houghton(Houghton 1991)1991).. DescriptionsDescriptions ofof thethe importantimportant GHGs andand theirtheir sources areare asas follows:follows:

WATERWA TER VAPOUR (HP)(F120) - -Water Water vapour vapour isis thethe mostmost abundant of thethe GHGsGHGs andand hashas thethe largestlargest greenhousegreenhouse effect. The amount of waterwater vapourvapour is onlyonly slightlyslightly affectedaffected byby humanhuman activities suchsuch asas irrigationirrigation andand developmentdevelopment ofof reservoirs.reservoirs. The amount of waterwater vapourvapour vvillwill increaseincrease if thethe atmosphereatmosphere becomes warmer. IncreasedIncreased amounts of waterwater vapourvapour couldcould enhance the greenhouse effect.

CARBON DIOXIDEDIOXIDE (CO2)(CO,! -. Carbon dioxidedioxide isis thethe mostmost important of thethe GHGsGHGs influenced byby humanhuman activityactivity both in terms of thethe amountamount inin the atmosphereatmosphere and potentialpotential effectseffects on global warming. ThisThis gasgas isis aa productproduct ofof respirationrespiration by animals and plants, the burning of fossil fuels and the burning or decompositiondecomposition of plants and trees. CementCement factoriesfactories areare another important sourcesource ofof CO,CO 2 (IPCC(lPCC 1992).1992).

Since the beginning of the IndustrialIndustrial Revolution,Revolution, in thethe midmid 18th century,century, thethe burningburning of fossil fuels hashas increased.increased. Extensive deforestation andand burningburning of debris hashas alsoalso occurred. TheseThese andand otherother humanhuman activities havehave resultedresulted in an increase inin the concentrationconcentration of carboncarbon dioxide in thethe atmosphere byby aboutabout 25%25% from 290 ppmvppmv (parts(parts perper million Climate Change, Forests and Forest Management 19 by volume)volume) toto 355355 ppmv at present. MostMost ofof thisthis increaseincrease has taken place sincesince 1940 (Hair(Hair and SampsonSampson 1992).1992). RecentlyRecently a reductionreduction inin thethe raterate ofof increase increase ofof atmospheric atmospheric CO2CO, hashas been detecteddetected (Sarimento(Sarimento 1993, see box 2.1).

METHANE (CH.)(CH4) - -The The majormajor sourcesource ofof methane is anaerobic decomposition (decomposition by micro-organismsmicro-organisms withoutwithout the presence ofof freefree oxygen in the air).air) . ThisThis occursoccurs inin ricerice paddiespaddies and naturalnatural wetlandswetlands.. MethaneMethane isis alsoalso a product of cattle andand other ruminants, including wildlife whosewhose digestivedigestive systemssystems rely on enteric· fermentation. AnotherAnother sourcesource ofof methanemethane isis termites, whichwhich areare presentpresent inin largelarge numbers inin tropicaltropical forestsforests (Zimmerman et et al 1982).1982). Other sources includeinclude biomassbiomass burning andand decompositiondecomposition fromfrom landfillslandfills andand wetlands.wetlands. Forest fires emit one unit ofof methanemethane for every 100 unitsunits ofof carboncarbon dioxide. TheThe levellevel ofof methane methane in in thethe atmosphereatmosphere hashas increasedincreased from 0.80 .8 ppmvppmv in 1850 toto 1.71.7 ppmvppmv atat present.present. SinceSince 1970,1970, for reasonsreasons unknown, thethe rate rate of of increase increase of of CH4 CH. inin the Earth's atmosphere has declineddeclined ffromrom aboutabout 2020 ppbvlyrppbv/yr to asas low asas 10 ppbv/yr (IPCC(IPCC 1992).

NITROUS OXIDEOXIDE (N,DJ (N20) - -This This gas gas is is emittedemitted asas aa result of deforestation andand associated burning, biomass burning, intensificationintensification of soilsoil nitrification andand denitrificationdenitrification processesprocesses inin intermittently wetwet areas,areas, applicationapplication ofof nitrogennitrogen fertilizersfertilizers and combustioncombustion of fossil fuels.fuels. 20 Climate Change, Forests and Forest Management

Box 2.1. WhatWhat happened happened to to atmosphericatmospheric

COCO2 2 levelslevels inin 19911991 ??

According toto datadata fromfrom thethe MaunaMauna LoaLoa Observatory inin Hawaii,Hawaii, USA,USA, aa 3535 yearyear trend of steadily increasing levelslevels of atmospheric CO2CO, was broken beginningbeginning inin mid-1991 when CO,CO2 levels were approximately 355355 ppmv.ppmv. ByBy late 1993,1993, aa reduction of 1.51.5 partsparts perper millionmillion (ppmv)(ppmv) of atmospheric CO2CO, was was detected. detected. If thisthis were applied toto the entire northern hemisphere, it would equate to a loss of 1.6 GtGt (1.6(1.6 xx 10910' tonnes) of carbon. ThisThis reductionreduction inin rate of CO2buildupCO, buildup began shortlyshortly after the eruption of thethe PhilippinePhilippine volcano,volcano, Mt.Mt. PinatuboPinatubo inin 1991 andand occurredoccurred despite the fact thatthat anan ENENSO SO occurredoccurred duringduring 1991-92. ENSOs normally result inin aa temporarytemporary increaseincrease inin atmospheric 002.CO,.

The causecause ofof this phenomenonphenomenon is not known. Some scientists believe that aa natural factor involving the oceansoceans or the terrestrial biospherebiosphere isis responsible.responsible. One possibility isis that ashash fallout,fallout. highhigh inin ironiron oxides, from the eruption of Mt.Mt. PinatuboPinatubo caused anan iron fertilization of thethe oceansoceans which temporarily increased theirtheir abilityability to absorb CO2CO, (Sarimento(Sarimento 1993). If the Pinatubo eruptioneruption is the mainmain cause,cause, thenthen the slowdown shouldshould bebe shortshort lived.lived. Climate Change,Change, Forests and ForestForest ManagementManagement 21

Relatively littlelittle is presently known aboutabout the ratesrates ofof releaserelease of this gasgas fromfrom soilssoils inin naturalnatural andand disturbeddisturbed ecosystemsecosystems andand from burningburning ofof biomass.biomass. The present level of N20N20 in thethe atmosphere is about 0.3 ppmvppmv andand isis increasingincreasing at the raterate ofof 0.2 toto 0.3%0.3% perper year.year.

CARBON MONOXIDE (CO)(CO) -- Carbon monoxidemonoxide isis notnot a true GHG. However it influencesinfluences the oxidizingoxidizing capacity of thethe Earth's atmosphereatmosphere and thusthus contributes to increasedincreased concentrations of methanemethane andand nitrousnitrous oxides.oxides. Burning of savanna grasslandsgrasslands as as a a form ofof livestocklivestock andand pasturepasture management may bebe the largestlargest singlesingle sourcesource becausebecause largelarge quantities ofof COCO areare emittedemitted asas aa resultresult ofof incomplete incomplete combustion andand smoulderingsmouldering rather than hot,hot, rapidrapid burning.burning.

NITROGEN OXIDES (NO),(NO), SULPHURSULPHUR DIOXIDEDIOXIDE (SO2).(SO). OZONE (0)(03) ANDAND CHLOROFLUOROCARBONSCHLOROFL UOROCARBONS (CFC-11(CFC-11 andand CFC-12) -- These GHGs areare the the resultresult ofof non-biotic, industrial processesprocesses such as thethe burning ofof fossil fuels, thethe chemicalchemical industry andand certain household appliances. ForestryForestry andand land use practices are notnot sources of thesethese GHGs.GHGs.

Ozone isis a gas which occursoccurs throughoutthroughout thethe atmosphere although most of it residesresides in the stratosphere where it acts as a protectiveprotective shieldshield andand preventsprevents harmfulharmful ultravioletultraviolet (UV)(UV) radiation from reachingreaching the Earth'sEarth's surface.surface. InIn the lowerlower atmosphere (troposphere) 0.30 3 isis formedformed asas aa resultresult ofof lightninglightning or asas aa componentcomponent ofof photochemical photochemical smog.smog. Exposure to elevated levels of tropospheric 030 3 can cause damage toto plants and bebe detrimentaldetrimental toto humanhuman health.health. CertainCertain varieties ofof beansbeans and tobacco are knownknown to bebe sensitivesensitive to elevatedelevated levels of

003.3 , SeveralSeveral speciesspecies of trees can sustain injury as a result of exposure toto elevated levelslevels ofof this gasgas (Jacobson(Jacobson and HillHill 1970).

CFCs, whichwhich were onceonce usedused asas aerosolaerosol propellantspropellants andand areare still used in air conditioning systems promote the destruction of stratosphericstratospheric 030 3 and contribute to itsits depletion.depletion. This isis 22 Climate Change, Forests and Forest Management believed to causecause seasonalseasonal ozone holesholes toto appear over the polar regions.

7. WHAWHAT T IS THETHE SIGNIFICANCESIGNIFICANCE OF HUMANHUMAN SOURCESSOURCES OFGHGS?OF GHGS?

Human activities are causing increases inin thethe emissionsemiSSions of some GHGs into thethe atmosphere.atmosphere. Major human sources of GHG emiSSionsemissions include the burning of fossil fuels, deforestation (and(and associatedassociated burning)burning) to makemake additional landland available forfor agriculture and grazing andand thethe burning of wood and charcoal. ApproximatelyApproximately 77 Gt Gt of of CO2 CO, werewere releasedreleased into the atmosphereatmosphere each year during thethe 1980s1980s fromfrom humanhuman sources (see question 23).23). Approximately 75-80%75-80% of this increase isis duedue toto industrialindustrial sources.sources. Most ofof thethe remainderremainder isis due to deforestationdeforestation and land use practicespractices (Watson etet al 1990). OtherOther sources sources ofof GHGs GHGs includeinclude paddy rice production and animalanimal husbandryhusbandry.. The latterlatter twotwo activities areare sourcessources of methane.

For overover a century,century, scientists have warned that thesethese increasing emissions maymay effect thethe atmosphere'satmosphere's radiativeradiative balance leading toto a significant andand long-term increaseincrease in the Earth's temperature (Plass 1959,1959, Hepting 1963).

8. DO ALL GHGSGHGS HAHA VE AN EQUAL WARMINGWARMING EFFECT? EFFECT?

No; GHGs varyvary bothboth inin the timetime theythey areare presentpresent inin thethe atmosphere before they breakbreak down (residence(residence times) andand in their radiative,radiative, oror warmingwarming effecteffect relativerelative toto carbon carbon dioxide.dioxide. Scientists havehave designated carbon dioxide the benchmark GHGGHG against which thethe propertiesproperties ofof all all otherother GHGs GHGs are are measured.measured. In order toto compare thesethese gases, thethe concept of relativerelative globalglobal warming potential (GWP) waswas developed asas a meansmeans ofof accounting forfor differencesdifferences in in residenceresidence timestimes andand thethe radiativeradiative effects ofof GHGsGHGs (Table(Table 2.1).2.1). Methane, for example,example, isis aa Climate Change,Change, ForestsForests andand ForestForest ManagementManagement 23 relarelativelyt ively short-lived gas,gas, consequentlyconsequently emissionsemissions from this gas would havehave theirtheir greatestgreatest impactsimpacts onon climateclimate changechange duringduring thethe firstfirst fewfew decades decades afterafter they they are are released. released. Nitrous oxideoxide and CFCs, on the otherother hand,hand, contributecontribute toto the the greenhouse greenhouse effect forfor hundreds hundreds ofof years years because because theythey are are moremore stablestable andand decompose very slowly in the atmosphere (IPCC 1992,1992, 1994)1994)..

99.. WHAWHAT T EVIDENCEEVIDENCE EXISTS TOTO SUPPORTSUPPORT THETHE IDEAIDEA THATHAT T GHGGHG LEVELSLEVELS ININ THETHE ATMOSPHERE A TMOSPHERE AREARE INCREASING?

There is strongstrong evidence thatthat the levels of several atmosphericatmospheric GHGs havehave increasedincreased ovoverer thethe past 150 years.years.

In 1958,1958, thethe first first continuous continuous CO2 CO 2monitoring monitoring programmes programmes began at stations in Mauna Loa, HawaiiHawaii andand Antarctica.Antarctica. DataData from thisthis monitoringmonitoring clearlyclearly showsshows anan annualannual increaseincrease iinn the mean annual concentratconcentrationion of of COCO2.2 • AsAs of 1990,1990, thethe globalglobal mean value was 355 ppnnv.ppmv. ThisThis is 25% above the 18501850 value value of 280-290280-290 ppmv ppmv (Fig (Fig 2.3)2.3) (Houghton(Houghton 1991,1991 ,Siegenthaler Siegenthaler andand Sanhuezza 1991)1991)..

The concentration ofof methanemethane inin thethe atmosphereatmosphere isis presentlypresently 1.7 ppmv,ppmv, moremore thanthan doubledouble the 18501850 value.value. Ice corecore analyses showshow that levelslevels of this gasgas remained fairly constant during the 2000 yearsyears prior toto industrializationindustrialization.. DuringDuring the ice ages, the concentration of methanemethane inin thethe atmosphereatmosphere waswas half ofof thethe presentpresent dayday level.level. Today's concentration of this gas is higher thanthan atat any timetime in the past 1501 50 000000 years.years.

During thethe 1980s,1980s, thethe ratesrates ofof methane methane increase increase declined,declined, dropping fromfrom 1616 ppbvppbv/yr/yr inin 1980 to aboutabout 1010 ppbv/yrppbv/yr byby 1990. RatesRates ofof methanemethane buildup slowed dramatically in 1991 and 19921992 butbut therethere areare indicationsindications thatthat they they increased increased againagain late inin 19931993 (IPCC(lPCC 1994).1994). 24 Climate Change, Forests and Forest Management

TABLE 2.1

DIRECT GLOBAL WARMINGWARMING POTENTIALPOTENTIAL OFOF REPRESENTATIVEREPRESENTATIVE GREENHOUSE GASES GASES FOR FOR A A 100100 YEAR TIME HORIZONHORIZON (Source: IPCCIPCC 1992,1992, 1 1994)9 9 4)

GHG Global Warming Potential Relative to Carbon DioxideDioxide

COCO2, 1 CH.CH4 11 N,ON20 320 CFC-11CFC-1 1 4000 CFC-12CFC- 1 2 85008 500 HCFC-22HCFC-2 2 17001 700 HFC-134aHFC-1 34a 13001 300

360c------~360 350 ,;- ~ 340 "- ';; 330 o .~ 320 ) ;Po C 310 0 ~ 0 u d'''' 5 300 0(JP u goO' 00 0 290 c Q::flJ CbocP (J o 00 o 280 o 0

270~~~~~~~~~~~~~~~~~~~270 1700 1800 1900 2000 Year

Figure 2.3 - ChangesChanges in the levels of atmospheric CO2CO, overover thethe past 250 yearsyears as indicatedindicated byby analysis ofof ice core data from thethe Antarctic andand byby atmosphericatmospheric measurementsmeasurements at MaunaMauna Loa, Hawaii since 1958 (Source:(Source: SiegenthalerSiegenthaler andand SanhuezzaSanhuezza (1991) ClimaClimate te Change, Forests and Forest Management 25

The present day concentration ofof nitrousnitrous oxidesoxides isis about 0.31 ppmv (parts perper million byby volume).volume). This is 8% higherhigher thanthan pre-industrial times. CFCsCFCs areare exclusively ofof humanhuman originorigin andand are recentrecent componentscomponents ofof the Earth's atmosphere. TheyThey havehave been studiedstudied intensively not onlyonly becausebecause of their greenhousegreenhouse effect butbut becausebecause they are depleting stratosphericstratospheric ozone.ozone. In 1990, thethe atmosphericatmospheric concentrationconcentration of thethe twotwo mostmost importantimportant CFCs,CFCs, CFC-11 andand CFC-12CFC-12 werewere 0.280.28 ppmv andand 0.48 ppmvppmv respectivelyrespectively (Houghton(Houghton 1990).1990).

10, WHICH COUNTRIESCOUNTRIES PRESENTLYPRESENTL YMAKE MAKE THETHE CREAGREA TESTTEST CONTRIBUTIONCONTRIBUTION TOTO ELEVAELEVA TED LEVELS OF GHGS?

The ten leadingleading contributors ofof GHGGHG emissionsemissions are the USA,USA, the formerformer USSR,USSR, Brazil,Brazil, China,China, India,India, Japan,Japan, Germany,Germany, UK,UK, IndonesiaIndonesia andand France.France. ManyMany ofof thesethese countriescountries havehave aa largelarge industrialindustrial and service sector and burn largelarge volumesvolumes ofof fossil fuelsfuels (Watson etet al 1990).1990). Developing countries (including(including China andand thethe formerformer USSR) accounted accounted forfor 36%36% of the globalglobal energy related carbon emissionsemissions inin 1990.1990. ThisThis representsrepresents anan increaseincrease fromfrom an estimated 28% inin 1970 (Global Environmental Change ReportReport 1994).

11. HOW CANCAN AEROSOLSAEROSOLS COUNTERACTCOUNTERACT THETHE EFFECTS EFFECTS OFOFGHGS? GHGS?

Aerosols consist ofof dust andand otherother tinytiny particlesparticles whichwhich areare releasedreleased intointo thethe Earth's atmosphere.atmosphere. ManyMany aerosolsaerosols act as nuclei forfor the condensation ofof water droplets which makemake up clouds.clouds. WithoutWithout condensation condensation nuclei,nuclei. cloudsclouds cannotcannot formform andand rain could not occur.occur.

There are numerous natural andand humanhuman sourcessources ofof aerosols.aerosols. Dust from erupting volcanos or desert sandsand stormsstorms areare twotwo 26 ClimateClimate Change, ForestsForests andand ForestForest ManagementManagement examples of naturalnatural sources.sources. The black soot producedproduced byby forest, savannasavanna and rangeland firesfires cancan bebe eithereither aa naturalnatural or human sourcesource dependingdepending on on the the cause cause of of the the fire. fire. The most significant humanhuman sourcesource ofof aerosolsaerosols is thethe emissionemission of sulphates fromfrom power generating stationsstations which cancan causecause acid rainra in (IPCC((PCC 1994).

Aerosols maymay counteract thethe warming effect causedcaused byby elevated levels ofof GHGs. They help to cool the atmosphere in two ways.ways. TheThe primary primary effecteffect is is toto scatterscatter sunlight,sunlight, reducingreducing the amount that reachesreaches thethe Earth's surface.surface. AnAn increaseincrease inin the levellevel of aerosolsaerosols cancan alteralter thethe densitydensity andand consequentlyconsequently the reflectance of clouds and cause aa coolingcooling effecteffect.. ThereThere isis evidence fromfrom Australia, the United States and countries of the former USSRUSSR thatthat the amount of cloud cover overover thesethese regionsregions has increased.increased. Consequently, some climatologistsclimatologists predict that some areas ofof the world may actually experienceexperience a cooling effect inin thethe futurefuture (Pearce(Pearce 1994). Climate Change, Forests and Forest ManagementManagement 27

Chapter 3 PREDICTED CHANGES IN THE EARTH'SEARTH'S CLIMATE AND EXPECTED EFFECTS

12. IN GENERAL,GENERAL, WHATWHA T ARE THETHE PREDICTEDPREDICTED EFFECTS OF INCREASED LEVELSLEVELS OF OF GHGSGHGS ONON THE EARTH'S CLIMATE?CLIMA TE?

IncreasesIncreases inin' atmospheric levels ofof CO2CO 2 and otherother GHGsGHGs can have far reaching effects. TheyThey include include increases increases inin averageaverage temperatures and changes inin precipitation, numbers of frostfrost free daysdays andand thethe frequencyfrequency and severityseverity ofof stormsstorms (see(see question 15). ThereThere isis alsoalso aa likelihoodlikelihood thatthat oceanocean levelslevels maymay rise (see question 17).17).

Green plantsplants utilizeutilize COCO22 during during photosynthesis. photosynthesis. Consequently increased levelslevels ofof GHGsGHGs can havehave potentiallypotentially significantsignificant effects onon thethe growthgrowth andand survivalsurvival ofof greengreen plants,plants, includingincluding trees (see questionquestion 18). InIn addition,addition, changeschanges inin climateclimate couldcould effect thethe distributiondistribution ofof animals animals and and plantsplants (see(see questions 33 and 34) andand thethe processesprocesses involved in soilsoil formationformation (see(see question 19). TheseThese effectseffects could could havehave seriousserious implicationsimplications inin the futurefuture forfor agriculture,agriculture, fisheriesfisheries andand forestry.forestry.

13. HOW AREARE CHACHANGES NGES IN THETHE EARTH'SEARTH'S CLIMATECLIMATE PREDICTED?

The general circulationcirculation modelmodel or or GCMGCM isis thethe most highlyhighly developed tooltool available withwith which to predictpredict changeschanges in the future world's climate.climate. AtAt least least 12 12 different different GCMs GCMs areare now in use. These areare based onon thethe laws ofof physicsphysics andand useuse descriptions ofof naturalnatural processesprocesses suchsuch asas cloudcloud developmentdevelopment and deep mixingmixing in thethe oceansoceans.. InIn thethe mostmost recentrecent GCMs,GCMs, anan atmospheric component, essentially the same as a weatherweather 28 Climate Change, Forests andand Forest Management prediction model, is coupled toto a model ofof the ocean. SomeSome of thethe moremore widelywidely used used GCMsGCMs are:are:

GISS - Goddard Institute of Space Sciences

NCAR-NCAR - National Center for Atmospheric Research

UKLO, UKHIUKHI- - UK Meteorological Office

GFLO, GFHIGFHI- - Geophysical Fluid Dynamics Laboratory

CCC - Canadian Climate Centre

To makemake a forecast of future climate,climate, the model ;sis first runrun over a simulated period ofof a few decadesdecades with nono changeschanges in the present atmospheric levelslevels ofof GHGs.GHGs. TheThe statistical statistical outputoutput is a description of the model's predicted climateclimate which,which, ifif the model is a good one, will bear a close resemblanceresemblance toto today'stoday's climatic conditions. TheThe exerciseexercise is then repeated withwith a newnew set ofof atmosphericatmospheric conditionsconditions (e(e.g..g. the equivalentequivalent ofof aa doubling of CO2CO, levels, see question 8, TableTable 2.1).2.1). The differences between the outputs of thethe twotwo simulationssimulations (e.g.(e.g. mean temperaturetemperature oror inter-annualinter-annual variability) provide anan estimate ofof climateclimate changechange (Fig 3.1).3.1). TheThe longlong term changechange in surface air temperature following aa doublingdoubling ofof carboncarbon dioxidedioxide isis used asas aa standardstandard toto comparecompare predictionspredictions byby differentdifferent GCMs. TheThe outputs areare different betweenbetween modelsmodels which taketake an immediate doublingdoubling ofof CO2CO, asas a startingstarting pointpoint whenwhen compared toto transienttransient modelsmodels whichwhich applyapply moremore gradualgradual increases in CO2CO, concentrations.concentrations. Climate Change, Forests and ForestForest ManagementManagement 29

\c)e} DJDFF 22 XX 002CO2· - , X CO2 PRECIPITATION:PRECIPtTATION: UKHIUKHI

....bor

- 0)

: ------_____ ,,' ¡------_, -- , ---- ,---;1--- :

(f)In JJA 2 X CO2CO2., - 1 X CO2C02 PRECIFTATION:PRECIPrrATION, UKHIUKHI, .

Figure 3.1 3.1 - AnAn exampleexample ofof aa predictionprediction ofof globalglobal changechange inin precipitation for winterwinter (top)(top) andand springspring (bottom)(bottom) producedproduced byby thethe UKHI GeM.GCM. AreasAreas ofof decrease decrease areare stippled.stippled. 30 Climate Change, Forests and Forest Management

Another approach toto predicting future climate change is to search forfor periodsperiods in thethe Earth'sEarth's pastpast whenwhen globalglobal meanmean temperatures were similar toto those at present or expected in the futurefuture.. It isis necessary for factors such asas greenhouse gas levels, orbital variations, and other conditionsconditions such asas iceice cover and topographytopography toto be similar inin orderorder toto get a goodgood prediction usingusing thisthis approachapproach.. PeriodsPeriods inin thethe Earth'sEarth's historyhistory with levelslevels ofof GHGsGHGs which are similar toto today'stoday's or predicted for thethe nextnext 100-200100-200 yearsyears havehave notnot yet beenbeen foundfound (Houghton 1991)1991)..

1414., HOW RELIABLERELIABLE AREARE PRESENTPRESENT PREDICTIONSPREDICTIONS OF CLlMACLIMA TE CHANGE?

Predictions ofof climate changechange are uncertain because ofof ourour imperfect knowledge of future ratesrates of emissions, thethe climaticclimatic response toto these changes and ofof weaknesses inherentinherent inin the models used toto forecast climateclimate change.change.

Future climate changes willwill depend, amongamong otherother factorsfactors,, on the rate at which GHGsGHGs areare emittedemitted (see(see quest questionion 9). 9). ThisThis willwill be influenced byby aa numbernumber ofof inter-related inter-related socio-economicsocio-economic factors. In addition,addition, becausebecause ofof our imperfectimperfect levellevel ofof knowledge ofof thethe sourcessources andand sinkssinks ofof GHGs,GHGs, therethere areare uncertainties inin thethe calculationscalculations ofof futurefuture concentrationsconcentrations arising from anyany emissionsemissions scenarioscenario entered into aa GCM.GeM. Because naturalnatural sourcessources andand sinks of GHGsGHGs are themselves sensitive to changing climate, they could substantially modify future concentrations.concentrations. For example, ifif wetlands were to become warmer, methanemethane emissionsemissions couldcould increase.increase. If they were to becomebecome drier,drier, moremore methanemethane wouldwould bebe absorbed.absorbed. There are also important processesprocesses inin the oceans which cancan effect GHGGHG concentrations (see(see question 4).

The models used to predict climate changechange areare only asas good as our understandingunderstanding ofof the processesprocesses whichwhich affect climate.climate. Presently thisthis isis farfar fromfrom perfectperfect.. TheThe rangerange ofof variabilityvariability ofof Climate Change, ForestsForests and Forest ManagementManagement 31 climate predictions by different GCMsGCMs reflectsreflects model imperfections. The largestlargest ofof thesethese uncertaintiesuncertainties isis ourour understanding ofof the factors whichwhich affectaffect cloud cloud abundanceabundance and distribution and the interactioninteraction of cloudsclouds withwith solarsolar radiation.radiation. OtherOther uncertainties uncertainties arise arise fromfrom thethe transfertransfer ofof energyenergy between thethe atmosphereatmosphere andand thethe ocean,ocean, thethe atmosphereatmosphere andand land surfaces, and between the variousvarious layerslayers in thethe oceanocean (Ma(Maunder under 1990).1990).

Another pointpoint toto keepkeep inin mindmind isis thatthat present present GCMsGCMs describedescribe the climate forfor anan equilibrium situation (eg(eg the situation arisingarising from aa doublingdoubling ofof CO2 CO, concentrationconcentration inin thethe atmosphere). atmosphere). They give no indication of howhow thisthis equilibriumequilibrium willwill be be reachedreached or how muchmuch timetime willwill bebe requiredrequired toto reachreach it.it.

15. WHATWHA T CHANGESCHANGES ININ CLIMA CLlMA TE ARE PREDICTED WITHWITH A DOUBLINGDOUBLING OFOF CO2 CO, FROM FROM PRE-INDUSTRIAL PRE-INDUSTRIAL REVOLUTION LEVELS?LEVELS?

Based onon outputsoutputs of several GCMs; temperatures areare expected to rise,rise, precipitationprecipitation willwill generallygenerally increase,increase, thethe climateclimate maymay become moremore variablevariable andand therethere could be anan increaseincrease inin incidence of tropicaltropical storms.storms. TheseThese changeschanges areare discusseddiscussed inin more detail inin thethe followingfollowing paragraphs.paragraphs.

TEMPERATURETEMPERA TURE -- GCMs predict aa range of temperaturetemperature increase betweenbetween 1.5 to 44.5°C.5°C with aa doublingdoubling ofof CO2CO, equivalents from level present duringduring thethe middle ofof the 19th19th century.century. This is expected toto occur at thethe raterate ofof 0.3°CO. 3°C ((± ± 0.2-0.5')0.2-0.5°) per per decadedecade duringduring the nextnext centurycentury andand couldcould resultresult in aa temperaturetemperature increaseincrease of 1°C1°C aboveabove presentpresent dayday levelslevels byby the yearyear 2025 and of 22°C°C before the end of the nextnext centurycentury (Houghton 1991). AccordingAccording toto somesome scientists,scientists, thisthis raterate ofof change is unprecedented in geologic history. 32 Climate Change, Forests and Forest Management

PRECIPITAPRECIPITATION TlON - -Increased Increased warming warming of of the the Earth'sEarth's surface will leadlead toto increasedincreased evaporationevaporation andand greatergreater averageaverage global precipitation. However, some regions may havehave reducedreduced rainfall. High latitude regionsregions areare expectedexpected toto experienceexperience increased movementmovement of of warmwarm moistmoist air toward thethe poles,poles, leading to increasedincreased annual precipitation andand river runoff.runoff. Existing GCMsGCMs givegive widely different estimatesestimates of newnew geographic patterns of precipitation/evaporationprecipitationlevaporation ratios.ratios.

CLlMACLIMA TICTIC VARIABILITYVARIABILITY --Changes Changes in in the the variability variability of of weather weather and the frequencyfrequency of extremeextreme climaticclimatic eventsevents willwill generallygenerally have more impact thanthan changeschanges inin thethe averageaverage conditions.conditions. However, with thethe possiblepossible exception of an increase inin the number ofof intense showers, there is no clear evidence that weather variability will changechange in thethe future.future. Assuming no change in temperature range,range, butbut a modest increase inin the average temperature,temperature, the the numbernumber of of daysdays withwith veryvery highhigh temperatures could increase substantially.substantially. ThereThere could alsoalso be a decreasedecrease inin days days with with veryvery coldcold temperatures.temperatures. Consequently the number of very hot or cold days could changechange substantiallysubstantially without changeschanges in the variability of the weather. TheThe numbernumber of daysdays withwith aa minimumminimum thresholdthreshold amountamount ofof soilsoil moisturemoisture required forfor certain crops could be affected byby changeschanges inin average precipitation (Houghton 1991).1991).

STORMS -- TropicalTropical storms such as typhoons andand hurricaneshurricanes develop when oceanocean surface temperatures areare inin excess of 26°C. Higher ocean surface temperaturestemperatures could thereforetherefore result inin anan increaseincrease in tropical stormsstorms andand resultantresultant damagedamage includingincluding damage toto forestforest resourcesresources (Fig(Fig 3.2). 3.2). While systems are available toto forecast stormsstorms inin advanceadvance (Gray(Gray 1993),1993). present day GCMsGCMs are unableunable to makemake suchsuch predictions.predictions. Consequently therethere isis aa great deal of uncertaintyuncertainty presentlypresently associated withwith the effects ofof climateclimate changechange on storm events (Houghton 1991). Climate Change, Forests and Forest Management 33

16. IS THE CLIMACL/MA TE OF SOME REGIONS OF THE WORLD EXPECTED TO CHACHANGE NGE TOTO AA CREA GREA TER TER DEGREEDEGREE THAN OTHERS?OTHERS?

Yes; there is general agreement among GCMs that there couldcould be a broadbroad latitudinallatitudinal climateclimate responseresponse duedue toto anan increasedincreased greenhouse effect. Warming could be much greater in thethe high latitudes and much lessless towardtoward thethe equator.equator. TheThe mostmost extreme temperature increases areare likelylikely toto occur in winterwinter inin the highhigh latitudelatitude ofof thethe northern northern hemispherehemisphere wherewhere changeschanges could be a muchmuch asas 22 1/2 1/2 timestimes greatergreater thanthan thethe globalglobal average. TheThe leastleast amountamount ofof changechange is predicted to occuroccur inin the tropics.

Predictions of regional changes inin climateclimate areare lessless clear.clear. One study, whichwhich comparescompares thethe predictionspredictions ofof severa! several GCMs,GCMs, indicates increasedincreased evaporationevaporation leadingleading toto increasedincreased summersummer dryness inin midmid-latitude-latitude continentalcontinental interiors.interiors. ManyMany ofof thesethese regionsregions areare ofof greatgreat agriculturalagricultural importanceimportance (Easterling 1990).

g: 1 tr.

4h-! \ 1.1viol; .3440

Figure 3.23.2 - Increases inin thethe numbernumber of of tropical tropical storms,storms, whichwhich cancan damage manymany resources includingincluding forests, forests, areare a possible,possible, but uncertain outcome of globalglobal climateclimate change.change. 34 Climate Change, Forests and Forest Management

17. WHATWHA T CHANGES ININ THETHE LEVEL OFOF THETHE OCEANS OCEANS AREARE EXPECTED DUE TOTO CLIMACL/MA TE CHANGE?

An overalloverall rise in sea level isis predictedpredicted.. This is based on thethe assumption that currentcurrent rates rates ofof increaseincrease inin the levelslevels of GHGsGHGs continue as predicted. ByBy 2100,2100, aa riserise inin oceanocean levels of 60 cm is expected. ThisThis isis largelylargely duedue toto thermalthermal expansionexpansion of the surfacesurface waters ofof thethe oceans.oceans. This could havehave severesevere effects onon smallsmall islandisland nations, countries with largelarge areasareas of lowlow lying coastal plainsplains and where large population centres are concentrated inin coastalcoastal regions.regions.

A rise in thethe ocean levellevel isis notnot expectedexpected toto bebe uniformuniform overover thethe entire globe. ThermalThermal expansion,expansion, changeschanges in ocean circulationcirculation and surface air pressure willwill vary from region to region as thethe climate changes. TheThe magnitudemagnitude of thesethese changes isis notnot yet known.

The most severe effectseffects of seasea levellevel rise are likely to resultresult from extremeextreme climatic events,events, such asas stormstorm surges,surges, thethe incidence ofof which couldcould alsoalso bebe affectedaffected byby aa changing changing climate (Houghton 19911.1991). This,This, however,however, isis oneone of thethe lessless certain predictions of the effectseffects ofof global global climateclimate change.change.

18. HOW WILLWILL PLANTS, INCLUDING TREES, BE INFLUENCED BYBY CHANGESCHA NGES ININ THETHE LEVELSLEVELS OFOF GHGs IN THETHE EARTH'SEARTH'S ATMOSPHEREA TMOSPHERE ANDAND RESULTANTRESUL TANT CHANGES IN TEMPERATEMPERA TURE ANDAND PRECIPITAPRECIPITATION TlON ?

The changes in levels of GHGsGHGs in the Earth's atmosphereatmosphere andand expected changeschanges inin climateclimc:te can havehave bothboth positivepositive andand negative effects onon plants.plants.

One of thethe potentialpotential positivepositive effectseffects ofof increasedincreased levelslevels of atmospheric CO2CO 2 isis known known asas the the "C0"CO22 fertilization fertilization effect". effect". It is knownknown thatthat CO2CO 2 isis a limiting factor inin plant growth.growth.

Increased atmosphericatmospheric COCO22 allowsallows more photosynthesis byby ClimateClimate Change, Forests and Forest Management 35

plants, resulting in at leastleast aa temporarilytemporarily higher growth raterate and rate of removal of atmospheric carbon by plants, provided that otherother requirementsrequirements forfor plant growthgrowth areare satisfied. LaboratoryLaboratory andand field experimentsexperiments indicate an increaseincrease inin photosynthesis of of aboutabout 30%30% in plantsplants whichwhich useuse thethe C3C3 photosynthesis processprocess withwith increasingincreasing root/shoot ratiosratios implyingimplying more underground storagestorage ofof carbon 2. AnAn increaseincrease inin the raterate ofof photosynthesisphotosynthesis of about 10% isis expectedexpected inin plantsplants which useuse thethe C4C. process.process. It isis likelylikely thatthat thethe gradualgradual

increaseincrease in atmospheric COCO22 over over the the past centurycentury hashas contributedcontributed partially to the approximate doubling of agricultural production worldwideworldwide which which has has been been achievedachieved largely through improvedimproved farmingfarming practices and genetic improvement of plantplant materials over the same period.period. ResearchResearch trials indicate that this fertilizingfertilizing effect wouldwould bebe mostmost effectiveeffective inin thethe lowerlower

rangesranges of thethe CO2CO 2 increase.

RelatedRelated toto thethe fertilizingfertilizing,. effect effect isis the the fact fact thatthat plantsplants contractcontract

their stomatal openingsopenings atat higherhigher levelslevels ofof atmospheric atmospheric CO2. CO 2 , This resultsresults inin lessless waterwater vapourvapour lossloss andand anan increaseincrease in the plant's water useuse efficiency. ThisThis impliesimplies thatthat increased increased plantplant growth maymay bebe possiblepossible in regions of the world wherewhere therethere isis low precipitation.precipitation. AA studystudy ofof the the possible possible effectseffects ofof higherhigher

water useuse efficiencyefficiency byby plants,plants, combinedcombined withwith thethe CO2 CO 2 fertilization effect, indicatesindicates that thethe areaarea wherewhere tropicaltropical rainforests could grow might increaseincrease by 75% withwith aa doublingdoubling

of atmosphericatmospheric CO2CO 2 andand thethe area of deserts could shrinkshrink byby 60% (Sombroek(Sombroek 1991).

22 Most plants assimilate cacarbonrbon by by oneone of of two two photphotosyntheticosynthetic pathways.

These are commonly referred to asas the C.,c; andand CC44 pathways. pathways. DuringDuring the first stagesstages of CO2CO2 absorption,absorption, CC33 plantsplants manufacturemanufacture a moleculemolecule witwithh threethree carboncarbon atomsatoms andand C4C. plants manufacture a8 fourfour atomatom molecule.molecule. The C4C. molecule enables thethe pplantlant to

assimilate CO,CO2 more efficiently. CC,3 plants depend on simple diffusion of CO2CO2 through their tissue andand thereforetherefore benefitbenefit more more thanthan C4 C. plants froirnIro(11 higher COCO,2 concentrations. PlantsPlants possepossessingssing thethe CC33 pathway pathway accountaccount forfor 85% ofof allall plantplant speciesspecies andand includeinclude all trees and woody plants.plants. PlantsPlants with thethe C4C. pathway areare tropicaltropical andand temperatetemperata grasses which grow inin areasareas of abundantabundant warmwarm seasonseason precipitation.precipitation. SugarSugar cane,cane,

maize, sorghum and millet areare allall C4C4 plantsplants.. 36 Climate Change, Forests and Forest Management

A higherhigher global temperature implies a degree ofof increase in plant production, especiallyespecially in high latitudes where thethe temperature rise would bebe proportionally greater according to the predictionspredictions ofof allall GCMs.GeMs.

Potential negative effectseffects ofof changeschanges inin temperaturetemperature andand precipitation onon plantsplants includeinclude (FAO(FAO 1990):

• High daily temperatures, eveneven ofof aa few hourshours duration, can causecause pollenpollen sterilitysterility in somesome crops such as rice and wheat.

• Increased cloudcloud covercover andand precipitationprecipitation in some regions couldcould resultresult in reduced yieldsyields ofof many crops. Rice yields, forfor example, cancan be 1 to 22 tonnes less per hectare inin rainy seasons thanthan inin dry seasonsseasons when grown underunder the samesame conditions.

• Areas with presentpresent day Mediterranean climatesclimates (mild, wet winterswinters andand hothot drydry summers) summers) areare predicted to becomebecome drierdrier resultingresulting inin reducedreduced soil moisture,moisture, especiallyespecially during thethe growinggrowing seasons. This wouldwould resultresult inin reducedreduced cropcrop production, reducedreduced growth ratesrates in forests andand increased riskrisk of wildfires.wildfires.

• The same conditionsconditions which result inin increasedincreased crop yieldsyields willwill alsoalso favourfavour weeds,weeds, enablingenabling them to bebe moremore competitive withwith crops.crops.

• Increased temperaturestemperatures could cause pests andand diseases toto extendextend theirtheir ranges,ranges, particularlyparticularly northward and intointo tropicaltropical highlandhighland regions.regions. Survival of overwintering populationspopulations could bebe higher and breeding cycles shorter with consequent increasesincreases inin the frequencyfrequency andand intensity ofof outbreaks.outbreaks. Climate Change, Forests andand ForestForest ManagementManagement 37

• The areasareas where certain agriculturalagricultural cropscrops andand tree species can grow may shift.shift. One studystudy indicates thatthat climate changechange could result inin aa shift ofof severalseveral hundredhundred kilometres ofof thethe NorthNorth American corncorn belt fromfrom the Southwest to the Northeast (Easterling(Easterling 1990).1990). Depending onon location, thisthis could be bothboth aa positivepositive andand negative effecteffect..

19. HOW MIGHTMIGHT SOILSSOILS BEBE AFFECTEDAFFECTED BYBY CHANGESCHANGES ININ CLIMATE?CLIMA TE?

Changing temperaturestemperatures cancan alteralter thethe raterate ofof microbialmicrobial activityactivity in soils. If temperatures increase, thethe raterate ofof microbial activity will increaseincrease proportionally. ThisThis willwill causecause organic matter to break downdown at faster rates,rates, whichwhich inin turnturn willwill accelerate accelerate thethe rate of CO2CO 2 release.release. The amount of carboncarbon storedstored inin soilssoils isis estimated toto be almostalmost twice thatthat inin thethe atmosphere atmosphere (see(see question 20). Consequently, aa smallsmall increaseincrease inin thethe rate of microbial activityactivity can bebe expectedexpected to makemake aa significantsignificant contribution toto amountamount ofof CO2 CO 2 in the atmosphere. SomeSome soilssoils are alsoalso sourcessources ofof NO.NO andand CH,.CH •.

Breakdown ofof organic mattermatter in soils results in aa releaserelease of nitrogen andand makesmakes it it availableavailable for for plant plant growth. growth. The rate of chemical weatheringweathering of mineralmineral soilsoil is alsoalso expectedexpected toto increaseincrease with increasedincreased temperatures,temperatures, makingmaking additionaladditional nutrients available forfor plantplant growth.growth. IncreasedIncreased availabilityavailability ofof soil nutrients could contributecontribute to acceleratedaccelerated plant growth (Grace 1991). 38 Climate Change, ForestsForests andand ForestForest Management

20,20. ISIS THERETHERE ANY EVIDENCEEVIDENCE WHICHWHICH INDICA TESTES THATHAT T CLIMATECLIMA TE CHANGES MAMAY Y HAHAVE VE ALREADALREADY Y OCCURREDOCCURRED DUEDUE TO INCREASESINCREASES IN GHG LEVELS?

In 1988, a droughtdreught occurred.occurred everover thethe centralcentral pertiensportions .ofof NerthNorth America resultingresulting inin massivemassive cropcrep failures.failures. This raisedraised speculatienspeculation amengamong scientistsscientists and thethe general publicpublic thatthat this dreughtdrought was thethe resultresult of.of anan increased increased greenhousegreenheuse effect. MereMore recent climatic events, such as a dreughtdrought everover much .ofof eastern and southernseuthern Africa which beganbegan during the 1991/1992 seasonseasen and affected nearlynearly 100100 millionmillien peoplepeeple (Cane(Cane etet alal 1994)'1994), severalseveral severe hurricaneshurricanes whichwhich battered the east coastceast of.of NorthNerth America,America, thethe majormajer floodingfleeding whichwhich .occurredoccurred inin the MississippiMississippi and MissouriMisseuri River Basins .ofof the United States in 1993, andand recordrecerd highhigh temperatures inin EuropeEurepe and NerthNorth America in the early 1990s1 990s couldceuld alsoalse lead .oneone t.oto believe thatthat the Earth isis beginningbeginning teto feelfeel thethe effectseffects of.of climate change.

MostMest climatologistsclimatelegists insist howeverhewever thatthat therethere isis notnet enough eneugh infermatieninformation tote determinedetermine ifif thesethese eventsevents areare due teto a changing climate orer areare partpart of.of normalnormal climaticclimatic variation.variatien. Droughts,Dreughts, floodsfleeds andand severesevere stormssterms havehave alwaysalways affectedaffected humanhuman secieties.societies. AtAt least least one.one study indicatesindicates that thethe features of.of the NorthNerth American dreughtdrought .ofof 19881988 werewere consistentcensistent withwith droughtsdreughts which occurred.occurred earlierearlier thisthis century.century. This wouldweuld suggest that therethere isis nothingnething newnewer or particularlyparticularly surprisingsurprising aboutabeut this drought.dreught. InIn fact,fact, precipitation precipitatien over ever the the past past decadedecade in thethe MidwesternMidwestern UnitedUnited StatesStates hashas beenbeen aboveabeve normal,nermal, particularly during thethe summer,summer, aa trendtrend centrarycontrary teto thatthat whichwhich someseme GCMs predict forfer anan increasedincreased greenhousegreenheuse respenseresponse in this regionregien (Easterling 1990).1990). InIn addition,additien, inin 1988,1988, the the yearyear of.of the NorthNerth AmericanAmerican drought,dreught, precipitationprecipitatien inin thethe SahelSahel regionregien of.of WestWest AfricaA frica beganbegan tote returnreturn tote normalnermal levelslevels after aa droughtdreught which lastedlasted overever 2525 yearsyears (Gommes(Gemmes 1993).1993). Climate Change,Change, Forests andand ForestForest ManagementManagement 39

Another complicatingcomplicating factor isis thatthat humanhuman populationspopulations havehave increased significantlysignificantly overover thethe past two toto threethree decades.decades. Consequently whenwhen climaticclimatic anomaliesanomalies suchsuch asas droughtsdroughts occur, moremore peoplepeople areare affected.affected. High human populationpopulation densities also lead to lessless resilientresilient agriculturalagricultural productionproduction systems. ThisThis amplifiesamplifies climaticclimatic anomalies.anomalies. LandLand degradation, cultivation ofof marginalmarginal lands withwith low natural fertilityfertility or water holding capacity andand shortershorter fallowfallow periodsperiods cancan exacerbateexacerbate drought conditions (Gommes 1993). ThisThis isis especiallyespecially true ofof regions such as Sudo-Sahelian AfricaAfrica and northeastern BrazilBrazil which havehave beenbeen historically proneprone to droughtdrought events.events.

The average global temperature hashas shown aa gradual increase of 0.3 toto 0.50.5 °C°C sincesince the 1850s.1850s. HoweverHowever thisthis trendtrend isis soso masked by annual andand regional variationsvariations that that itit is virtuallyvirtually impossible toto attribute thethe increaseincrease toto aa specificspecific cause.cause. 40 ClimateC//mate Change.Change, ForestsForests andand ForestForest ManagementManagement

Chapter 4 THE GLOBAL CARBON CYCLE

21.21, WHAT PROCESSESPROCESSES EXISTEXIST FORFOR THE EXCHANGEEXCHANGE OF CARBON BETWEEN THE AATMOSPHERE, TMOSPHERE. THE OCEANS AND THETHE LAND?

There isis aa finitefinite but extremely large amount of carbon on the Earth (Table(Table 4.1).4.1). CarbonCarbon occursoccurs in the ocean, in soils, fossil carbon reserves, bedrock,bedrock. the atmosphere and plant biomass. The carbon cyclecycle isis the movement of carbon, in itsits variousvarious forms, between thethe Earth's surface,surface. its interiorinterior and atmosphereatmosphere.. TheThe major pathways of the exchange of carbon are photo-synthesis,photo-synthesis, respirationrespiration and oxidation.oxidation. Movement occurs between living organisms,organisms, the atmosphere,atmosphere, the landland and water (Fig 4.1).4.1). OverOver thethe coursecourse of millions of years, the carbon cycle has concentrated large amounts ofof carbon inin bedrock, primarily as limestone and in fossil fuels.fuels.

The carboncarbon cyclecycle isis thought of asas fourfour interconnected interconnected reservoirs or pools; thethe atmosphere,atmosphere, thethe terrestrialterrestrial biospherebiosphere (including fresh water systems), thethe oceansoceans and thethe sedimentssediments (including fossilfossil fuels). TheThe exchangeexchange rate of carbon between pools is referred toto as flux.flux. TheseThese reservoirsreservoirs areare eithereither carboncarbon sources and sinks. CarbonCarbon sinkssinks absorb carbon from another part of thethe carboncarbon cyclecycle whilewhile carboncarbon sourcessources releaserelease carbon.carbon. For example,example, greengreen plantsplants absorbabsorb carboncarbon fromfrom the atmosphere and are consideredconsidered a a carbon carbon sink sink.. An industrialindustrial plantplant whichwhich releases carboncarbon inin the atmosphereatmosphere isis consideredconsidered aa carboncarbon source. Climate Change, Forests and Forest Management 41

22,22. HOW AREARE EXCHANGESEXCHANGES OFOF CARBONCARBON BETWEENBETWEEN RESERVOIRS EXPRESSEO?EXPRESSED?

Exchange betweenbetween reservoirs involvesinvolves largelarge amounts ofof carbon. ThisThis isis expressedexpressed inin multiplesmultiples ofof metricmetric tonnes.tonnes. The units used throughout this paperpaper are those widely usedused in the literature onon climate changechange andand carbon fluxflux andand areare defined asas follows:

1 teragramme.teragramme (Tg)(Tg) = 10101212 grams grams oror 106106 tonnes. 1 petagramme (Pg) = 11015 a" grams grams oror 1091 a' tonnes. 1 gigatonne (Gt)(Gt) =-= 1109 a' tonnestonnes or 11 Pg.Pg. 1 PgPg = 1 Gt.

Concentration of GHGsGHGs in thethe atmosphereatmosphere areare expressedexpressed as follows:

ppmv = Parts per million by volume.volume. ppbv == Parts per billion (thousand million) by volume.volume. pptv == Parts per trillion (million(million million)million) by volume.

TABLE 4.1

ESTIMATED DISTRIBUTIONDISTRIBUTION OFOF THETHE GLOBALGLOBAL CARBON POOLPOOL (Source:(Source: SombroekSombroek etet alal 199311993)

Component GtC

Oceans 3800038000 Fossil carbon reserves 6000 Soils Organic carboncarbon 1200 Calcium carbonatecarbonate 720 Atmosphere 720 Plant biomassbiomass 560·835560-835

Total 47220-47495 42 Climate Change, Forests and Forest Management

DEFORESTATION

ATMOSPHERE 750 + 3/YEAR3{yEAA

2 5

102 50 92 90

LAND BIOTABIOTA 550 SURFACE OCEAN 50 1000 +1/YEAR+l{yEAR SOILSQL AND AND DETRITUSDETRITUS BIOTA 3 _BIOTA 3 36 :Ow 1500 44-- 40

5 37 V INTERMEDIATE AND DEEP WATERS

3000038000 -- 2/YEAR2/YEAR

0.2

31j 4 °"°

Figure 4.14.1 - Schematic representation ofof the globalglobal carboncarbon cyclecycle showing movement of carboncarbon (in(in Gt)Gt) betvveenbetween carbon sources and sinks (Source: WatsonWatson etet al 1990). Climate Change, Forests and Forest Management 43

23,23. WHAWHAT T ISIS THE PRESENTPRESENT LEVELLEVEL OF CARBONCARBON EXCHANGE BETWEEN THE ATMOSPHERE,A TMOSPHERE, THETHE OCEANS ANDAND THE LAND?

According to estimates for the decade 1980-89, annual annual carboncarbon fluxes due toto CO2CO, exchangesexchanges werewere asas followsfollows (IPCC(lPCC 1994):

CO2CO, sources:

Fossil fuel emissions 5.5 ±0.5 GtC/yrGtC/yr

Net emissions fromfrom tropical landland use (deforestation(deforestation etc) 1.6±1.01.6 ± 1.0 Total emissionsemissions 7.0±7.0±1.1 1.1

CO2CO, sinks:

Accumulation inin thethe atmosphere 3.2±0.23.2 ±0.2

Uptake by the oceanocean 2.0 ±±0.8 0.8

Uptake by northern hemispherehemisphere forest regrowthregrowth 0.5 ±0.5±0.5

Additional terrestrial sinkssinks (eg CO,CO2 fertilization fertilization effect,effect, nitrogen fertilization andand climatic effects) 11.4±1.5 .4 ± 1 .5

The "additional terrestrial sinks" have not yet beenbeen quantified but are believed toto be thethe primary components ofof thethe soso calledcalled "missing carbon sink"sink" which isis yetyet toto bebe accountedaccounted for.for. 46 Climate Change, Forests and Forest Management

TABLE 5.15.1

LAND AREAAREA COVEREDCOVERED BYBY FORESTSFORESTS ANDAND OTHEROTHER WOODEDWOODED AREAS BY REGION (1980) (1980) (Source(Source:: LanLanlyly 1989,1989, FAO, unpublished data)

Region Forests (%)(%) Other wooded Total (%)1%) 1%)(%)

Africa 18.0 21.3 39.3 Americas 3737.0.0 15.2 55.2 Asia-Pacific 19.0 7.0 26.0 Europe·Europe 27.0 88.6.6 35.6

WORLD 27.0 13.0 4040.0 ..0

*• Includes RussiaRussia

main stems of trees.trees. Because of of thethe longlong lifelife span of most trees andand theirtheir relativelyrelatively largelarge sizes,sizes, treestrees andand forestsforests areare storehouses ofof carbon.carbon. Overall, forestsforests storestore fromfrom 2020 to 100 times more carbon per unit areaarea thanthan croplandscroplands andand playplay aa critical rolerole in regulatingregulating the levellevel ofof atmosphericatmospheric carbon.carbon. The world's forestsforests havehave beenbeen estimated to contain up to 80% of allall above ground terrestrial carbon and approximately 40% of allall belowbelow groundground terrestrialterrestrial carboncarbon (soil,(soil, litterlitter andand roots).roots). This amounts toto roughly 1146 GtC. Approximately 37%37% of this carbon is stored inin lowlow latitudelatitude (tropical) forests,forests, 14% in mid latitude (temperate)(temperate) forestsforests andand 49%49% in highhigh latitudelatitude forests (Dixon(Dixon et al 1994).

When trees die or are harvested, the stored carboncarbon isis released.released. Some ofof thethe carboncarbon becomesbecomes part of thethe organicorganic mattermatter component ofof forestforest soilssoils where,where, dependingdepending onon climaticclimatic conditions, it cancan remainremain for long periods. TheThe remainderremainder is released intointo the atmosphere,atmosphere, largelylargely asas CO2CO, but alsoalso asas CH,CH. or otherother GHGs.GHGs. The rate of releaserelease maymay be slow,slow, as in the case of aa singlesingle treetree dyingdying andand beingbeing subjectsubject to yearsyears ofof breakdown and decay by fungi, insects,insects, bacteriabacteria andand otherother Climate Change,Change, Forests and ForestForest ManagementManagement 47 organisms. OnOn thethe otherother hand, hand, aa suddensudden disturbance,disturbance, suchsuch asas a wildfire oror clearingclearing and burning of forests for agricultureagriculture andand settlement by humans,humans, cancan causecause aa rapidrapid releaserelease of largelarge volumes ofof GHGsGHGs into thethe atmosphere.atmosphere.

26. HOW MUCH MUCH CARBONCARBON ISIS RELEASEDRELEASED AND HOW MUCH IS TAKENTAKEN UPUP ANNUALLANNUALL Y BYBY FORESTS?FORES Ts?

Estimates forfor the yearyear 11990 990 indicate thatthat the lowlow latitudelatitude forests emitted 1.61.6 ±± 0.40.4 GtC GtC per per year year into into the the atmosphere, atmosphere, primarily due toto deforestation. This isis equivalent to approximatelyapprOximately 23% of the total carboncarbon emissionsemissions including the burning of fossil fuels. ThisThis waswas offsetoffset by by a a sequestrationsequestration ofof 0.7 ±± 0.20.2 GtC GtC per per year year byby forestforest expansion expansion andand growth inin thethe mid andand highhigh latitudeslatitudes (Table(Table 5.2).5.2). Consequently, there isis presently a net carboncarbon contributioncontribution ofof 0.90.9 ±± 0.40.4 GtC GtC perper yearyear to the atmosphere from the world's forestforest ecosystemsecosystems (Dixon(Dixon et alal 1994).1994). This is undoubtedlyundoubtedly duedue toto increasedincreased rates ofof tropical deforestation during thethe decade of thethe 1980s1980s (see(see question 25). AtAt the the beginning beginning ofof the the decade, decade, thethe estimatedestimated accumulation of carboncarbon inin recoveringrecovering tropicaltropical landscapeslandscapes which hadhad previouslypreviously beenbeen disturbed waswas roughlyroughly equalequal toto netnet carbon emissions due toto tropical deforestation andand associatedassociated burning (Lugo and Brown 1992).1992).

27. DO DIFFERENT FORESTFOREST ECOSYSTEMS VARY VARY IN IN THEIRTHEIR CAPACITY TO ABSORB AND STORE CARBON?CARBON?

Forests vary considerably in their capacitycapacity toto absorb absorb andand storestore carbon. Factors which influenceinfluence carboncarbon absorptionabsorption ratesrates include temperature, precipitation, stocking, soil, slope, elevation, site conditions,conditions, growthgrowth ratesrates andand age.age. Generally speaking, closedclosed forestsforests havehave aa greater capacity to storestore carbon than open forestsforests andand woodlands.woodlands. UndisturbedUndisturbed forestsforests store more carbon thanthan degradeddegraded forests. forests. WetWet oror moistmoist 48 C//mateClimate Change, ForestsForests andand ForestForest Management

TABLE 5.2

ESTIMATED ANNUAL RATESRATES OFOF CARBONCARBON EXCHANGE BETWEEN THETHE WORLD'SWORLD'S FORESTS AND THETHE ATMOSPHEREATMOSPHERE

Latitudinal Belt Carbon ExchangeExchange (Gt/Year)(GtfYear) * *** ••

High Russia +0.30 to +0.50+0.50 Canada +0.08

Subtotal +0.48 ±0.1±O.'

Mid USA'USA* +0.'0+0.10 to +0.25+0.25 Europe-Europe*"it ++0.09 0.09 to +0.12+ 0.'2 China -0.02 Australia trace

Subtotal +0.26 ±0.09±0.09

Low Asia -0.50 to -0.90-0.90 Africa -0.25 toto -0.45-0.45 Americas -0.50 toto -0.70-0.70

Subtotal -,-1.65 .65 ± 0.400.40

Total ·0.9-0.9 ± 0.4

*, Includes continental USAUSA andand Alaska.Alaska. **•• IncludesIncludes Nordic Nordic countriescountries it.*** it + +Indicates Indicates transfer transfer from from atmosphere atmosphere to forest.forest . -. IndicatesIndicates transfertransfer fromfrom forestforest toto atmosphere. atmosphere.

Source: Dixon et al 1994'994 C//mateClimate Change, Forests andand ForestForest ManagementManagement 4.949 forests storestore moremore carboncarbon thanthan drydry oror semi-aridsemi-arid forestsforests andand mature forests store greatergreater quantitiesquantities of carboncarbon thanthan dodo young forests.

Many studies havehave been conductedconducted to estimate the biomass of forest ecosystems.ecosystems. These can be used to estimateestimate carboncarbon storage. TheThe ratioratio ofof dry dry total total biomass biomass toto carbon carbon isis roughlyroughly 2:1.2: 1. The carbon content of anan undisturbedundisturbed tropicaltropical moistmoist forest cancan rangerange has high as 250 tC/hatC/ha ofof standing,standing, aboveabove ground biomass. TheThe carbon content of tropical, dry forestsforests with open,open, discontinuousdiscontinuous canopies,canopies, on thethe otherother hand,hand, generally averages less thanthan 40 tCtC/ha/ha (Brown andand Lugo 1984)1984) (Table 5.3).

Forest soilssoils alsoalso storestore carboncarbon.. A recentrecent study indicatesindicates that 84.3% ofof thethe totaltotal carboncarbon contentcontent ofof highhigh latitudelatitude forestsforests isis stored in thethe soil.soil. FoForr mid-latitudemid-latitude forests,forests, 63% isis storedstored inin the soil and forfor low latitudelatitude forests,forests, the proportion isis 50.4% (Dixon et al 1994) (Table(Table 5.4).5.41 .

28. DO TREESTREES ANDAND FORESTSFORESTS REMOVE CARBON FROM THETHE EARTH'SEARTH'S ATMOSPHEREA TMOSPHERE AAT T DIFFERENTDIFFERENT RATESRA TES DURING DIFFERENT STAGESSTAGES ININ THEIR LIVES?

The rate ofof carboncarbon absorptionabsorption byby trees and forests is aa function ofof growthgrowth ratesrates andand age. age . GenerallyGenerally speaking, speaking, treestrees and forests remove atmospheric carbon at high ratesrates whenwhen they areare youngyoung andand fastfast growing.growing. As standsstands approachapproach maturity and growth ratesrates areare reduced,reduced, thethe netnet carboncarbon absorption is also reduced. In theory,theory, mature forestsforests reachreach aa stage of equilibriumequilibrium withwith respectrespect toto carbon carbon absorption. absorption. Roughly an equal amountamount of carbon isis releasedreleased through decaydecay of deaddead and diseased treestrees asas isis absorbed.absorbed. HoweverHowever thisthis isis rarerarelyly achieved in naturalnatural forests.forests. Mature forests,forests, ifif leftleft undisturbed, as is the case in reserved or protected forests, are carbon reservoirs but not necessarilynecessarily net carbon sinks.sinks. 50 Climate Change, ForestsForests andand Forest Management

TABLE 5.3

ESTIMATES OF AVERAGE ABOVE GROUNDGROUND STOREDSTORED CARBON/HA BYBY VARIOUSVARIOUS VEGETATIONVEGETATION COMMUNITIESCOMMUNITIES (Based onon biomass valuesvalues fromfrom Olsen et al(1983))al(1 983))

Holdridge LifeLife ZoneZone tC/ha

Forest

Tropical wet lOO100 Tropical moist 70 Tropical dry 50 Subtropical wet 65 Subtropical moist 35

Warm temperate 50 Warm dry temperate 25 Cool temperate 50

Wet borealboreal 55 Moist borealboreal 40

Non Forest

Tropical thorn woodlandwoodland 15 Temperate thorn steppesteppe 8 Cool temperate steppesteppe 5 Tropical desert bushbush 2 Temperate desert bushbush 3 Boreal desert 5 Tundra 2.5 Climate Change,Change, Forests and ForestForest Management 51

TABLE 5.4

ESTIMATEDESTIMATED CARBON DENSITIESDENSITIES PERPER UNIT OF FORESTFOREST AREA ININ VEGETATION AND SOILSSOILS OFOF THETHE WORLD'SWORLD'S FORESTSFORESTS

Latitudinal Belt Carbon Densities (tC/ha)ItC/ha)

Vegetation Soils

High Russia 83 281 Canada 28 484 Alaska 39 212

Mean 64 (15.7%)115.7 %) 343 (84.3%)184.3%)

Mid USA 62 110808 EuropEurope*e· 32 90 China 114114 136 Australia 45 83

Mean 57 (37%)137%) 96 (63%)163%)

Low Asia 132-174 139 Africa 99 120 Americas 130 120

Mean 121 (49.6%)149.6%) 123150.4%)123 (50.4%)

• Includes Nordic countries.countries.

Source: Dixon et al 1994. 52 ClimateClifnate Change, Forests and Forest Management

Box 5.1 The role of forestforest .plantations plantations inin New Zealand'sZealand's carboncarbon balance.balance.

According to estimatesestimates made by a team of research scientistsscientists in NewNew Zealand,Zealand, thethe country's 1.241.24 millionmillion ha ofof plantation forests absorbed 4.54.5 ± 0.80.8 millionmillion tonnestonnes of carbon between 11 April 1988 andand 11 AprilApril 1989. The totaltotal aboveabove groundground carboncarbon stored in NewNew Zealand'sZealand's forestforest plantationplantation estate is approximately 88 millionmillion tonnes.tonnes.

Carbon absorptionabsorption by New Zealand's forest plantations for the period studied waswas equivalent toto approximatelyapproximately 70%70% of thethe country's fossil fuel emissions butbut <<0.1% 0.1 % of thethe totaltotal globalglobal fossilfossil fuelfuel emissions.emissions.

The high annual rate of carboncarbon uptakeuptake byby these plantations is aa consequenceconsequence ofof the large areaarea ofof newnew plantings plantings established established during the 1970s1970s andand 1980s.1980s. Without continued new plantings,plantings, thethe netnet annualannual rate of carbon absorption of these plantations will rapidly approach zero

(Hollinger etet al 1993) .. Climate Change, Forests andand ForestForest ManagementManagement 53

Studies of carbon absorption rates inin tropicaltropical forest plantations indicate that maximummaximum growthgrowth andand carboncarbon uptakeuptake occursoccurs during age classesclasses 0-50-5 andand 6-106-10 yearsyears (62%). CarbonCarbon uptakeuptake decreases by by aboutabout 50%50% during the nextnext 55 yearsyears andand decreases eveneven furtherfurther afterafter ageage 1616 (Brown etet al 1986).29.

29. WHICH HUMAN ACTIVITIES ININ FORESTSFORESTS ANDAND WOODLANDS CONTRIBUTE TOTO INCREASES IN THETHE LEVELS OF GHGS?

DEFORESTA TION TION - -Felling Felling and and burning burning ofof forestsforests to makemake landland available for agriculture oror livestock grazing,grazing, isis the major forest sector contributor to to increases increases in in the the levels levels of of GHGs GHGs andand isis the second largest humanhuman causedcaused sourcesource ofof GHGs. GHGs.

Human societiessocieties havehave beenbeen cutting cutting forestsforests forfor millennia.millennia. UntilUntil the early part of this century, deforestationdeforestation occurredoccurred mainly in temperatetemperate forests.forests. MoreMore recently,recently, itit has has beenbeen concentrated in the tropics. Deforestation,Deforestation, and and associatedassociated burning,burning, resultsresults inin a massive and rapid release of carbon intointo thethe atmosphere,atmosphere, primarily asas CO2.CO 2 , Smaller amounts of CH4CH, and COCO areare alsoalso emitted. TropicalTropical forestsforests playplay anan importantimportant rolerole inin thethe globalglobal carbon cyclecycle becausebecause they they store store about about 50% 50% ofof thethe world's living terrestrialterrestrial carbon (Dixon etet al 1994).1994). High rates of deforestation in the tropics is the reasonreason thatthat forestsforests presently make a net contribution toto atmosphericatmospheric carbon,carbon, despitedespite thethe fact thatthat theythey areare ableable toto storestore largelarge quantitiesquantities ofof carbon.carbon.

Deforestation cancan also alter climateclimate directlydirectly byby increasingincreasing reflectivity (albedo) and decreasing evapo-transpiration. Experiments with climate models predict that the replacementreplacement of all of the forests ofof thethe AmazonAmazon Basin with grasslandgrassland would reduce thethe rainfall over the basin by about 20%20% andand increaseincrease the average regional temperature byby severalseveral degreesdegrees (Maunder(Maunder 1990). 54 Climate Change, Forests andand ForestForest ManagementManagement

BIOMASSB/OMASS BURNINGBURNING -- The term "biomass burning" includes all intentionalintentional human activitiesactivities associated withwith forestforest clearing, the burning of savanna vegetationvegetation toto stimulatestimulate regenerationregeneration ofof grasses forfor livestock, burning of fuel woodwood andand charcoalcharcoal and consumption of agricultural residues. TheThe areaarea of savannasavanna vegetation burned eacheach yearyear isis estimatedestimated atat 750750 million ha. About half of thisthis areaarea isis inin AfricaAfrica (Fig 5.1)5.1).. Shifting cultivation, a practicepractice inin whichwhich thethe naturalnatural vegetationvegetation is cleared, used for agriculture for 22 to 55 yearsyears and then allowed to remainremain fallow and revegetate withwith natural vegetationvegetation forfor 7 to 1212 yearsyears beforebefore beingbeing clearedcleared again, isis practised byby 200 million people worldworld widewide onon 300 to 500500 millionmillion haha.. Approximately 87%87% of thethe biomassbiomass burningburning occurs inin the tropics.tropics.

W/LDFIRESWILDFIRES - -A A "wildfire""wildfire" isis defineddefined as any firefire occurring on wild (undeveloped)(undeveloped) lands except a fire under prescriptionprescription (one which isis setset intentionally)intentionally) (FAO(FAO 1986).1986). Recent estimates indicate thatthat between 12 and 1313 millionmillion ha of forestsforests andand other woodedwooded landslands areare burnedburned annuallyannually (Calabri(Calabri and CieslaCiesla 1992). WithWith the the exception exception ofof remote remote forestforest areasareas in portions of NorthNorth AmericaAmerica andand Siberia, most forest and other wildland fires are of human origin. HumanHuman causescauses of wildfireswildfires includeinclude escaped prescribed fires, carelessness,carelessness, andand arson.arson. Natural causes ofof wildwildfires fires are lightning storms, volcanicvolcanic activityactivity and burning of undergroundunderground peatpeat andand coalcoal deposits.deposits.

OTHER ACTIVITIES ACTIVITIES - -Other Other human human activities activities connectedconnected with forests and forestforest products which contribute to elevated levelslevels of greenhousegreenhouse gases include degradation ofof forestsforests andand disposal ofof wood products,products, especiallyespecially paperpaper products, after they havehave servedserved their periodperiod ofof usefulness.usefulness. Climate Change,Change, Forests and ForestForest ManagementManagement 55

FFigureigure 5.15.1 - An aerial vviewiew ofof a a brushbrush fire in thethe Sudan.Sudan . RoughlyRoughly 750 millionmillion haha ofof savannasa vanna vegetationvegetation areare burnedburned annually,annually, resultingresulting inin a massivemassive releaserelease ofof greenhousegreenhouse gases.gases.

30. WHAWHAT T ARE THETHE CURRENTCURRENT RATESRA TES OFOF DEFORESTADEFORESTATION TlON ININ THE WORLD'SWORLD'S FORESTS?FORESTS?

The average annual raterate of tropical deforestationdeforestation duringduring thethe decade ofof 1981-90 waswas 15.415.4 millionmillion haha (FAO(FAO 1993). TheseThese rates of deforestation areare roughlyroughly equivalentequivalent to thethe totaltotal landland area of Nepal, Nicaragua or Greece and resulted in a reduction in the area ofof tropicaltropical forests from 11 910910 millionmillion haha atat thethe endend of 19801980 toto 11 756756 million million haha atat thethe endend of 1990.1990. On On a a regional regional basis, the annual loss of forest covercover was:was: LatinLatin AmericaAmerica andand the Caribbean, 7.47.4 million ha (0.8(0.8%% of thethe totaltotal forestforest area),area), Asia and the Pacific, 3.9 million ha (1.2 %)%) andand Africa,Africa, 4.14 .1 million ha (0(0.7%)..7 % ). TheThe forest forest area area ofof the the temperatetemperate and and borealboreal zones did not changechange significantly duringduring thethe samesame period.period. 56 Climate Change, ForestsForests andand Forest Management

Annual rates of deforestationdeforestation in thethe tropicstropics havehave increasedincreased when compared to to thethe previousprevious decade. decade. DuringDuring thethe 1980s,1980s, the annual raterate of tropical deforestation was 11.3 millionmillion haha (Lanly 1982).

Forests inin developed temperatetemperate regionsregions nownow cover much smaller areasareas than than in in the the past. past. These forestsforests havehave historicallyhistorically contributed heavily to globalglobal carboncarbon emissions asas forests in Europe andand North AmericaAmerica werewere clearedcleared forfor agriculture.agriculture. However, the areaarea of thesethese forestsforests hashas stabilizedstabilized andand eveneven increased slightlyslightly over the past 100100 yearsyears as agricultural landslands were abandoned andand revertedreverted toto forest cover.cover. France, for example, hadhad forestforest covercover onon onlyonly 14%14% of the country's landland area inin 1798.1798. Today 27% of itsits landland areaarea isis forested.forested. Deforestation andand agriculturalagricultural developmentdevelopment in in thethe statestate of Vermont, USAUSA had reduced the surface area ofof forestforest cover to about 15% ofof thethe totaltotal landland areaarea about 100 years ago. TodayToday the state is 85% forested.forested.

31. HOW AREARE FORESTFOREST SOILSSOILS AFFECTED BYBY DEFORESTATION?DEFORESTA TlON?

In addition toto increasingincreasing susceptibilitysusceptibility ofof soils to erosionerosion by wind andand water,water, thethe clearingclearing ofof forestsforests andand woodlandswoodlands toto support agriculture inin thethe tropics can resultresult inin aa lossloss ofof 20 to 50% ofof thethe soilsoil carboncarbon containedcontained inin thethe topsoil.topsoil. Some estimates indicateindicate thatthat deforestation in the tropicstropics causedcaused a net release ofof betweenbetween 00.1.1 andand 0.30.3 Gt of soilsoil carboncarbon in the years aroundaround 19901990 compared withwith 0.3 andand 1.31.3 GtGt asas aa resultresult of burning and decay of vegetation respectively (Sombroek(Sombroek et al 1993). Climate Change, Forests and Forest Management 57

Chapter 6 POSSIBLE EFFECTS OFOF CLIMATECLIMATE CHANGE ONON FORESTSFORESTS

32,32. WHAWHAT T CHANGESCHANGES ININ GROGROWTH WTH AND YIELDYIELD OFOF TREESTREES AND FORESTSFORESTS CAN BEBE EXPECTED AS AS AA RESULRESULT T OF CLIMACL/MA TE CHANGE?

The implications of CO2CO, enrichmentenrichment on on growthgrowth andand yieldyield of trees and forestsforests areare stillstill unclear.unclear. Laboratory studies onon growth ratesrates andand yieldyield of plantsplants growngrown inin elevated elevated CO2CO, environments have documented increased rates of photosynthesis, lowered plant water useuse requirements, increased carbon sequestration andand increasedincreased soilsoil microbialmicrobial activity. These resultresult in higher rates of nitrogennitrogen fixation, thereby stimulatingstimulating growth. HoweverHowever in in aa naturalnatural ecosystem,ecosystem, where animalsanimals grazegraze onon plants,plants, diseasedisease organismorganism causecause damage and treetree deathdeath and plantsplants compete for available light, water andand nutrients, therethere areare serious doubts that production would actuallyactually increase.increase. In addition, higher growth andand yieldyield could be offset byby higherhigher losseslosses due to fire,fire, insectsinsects andand disease (See questionsquestions 35 and 36).

To date, little work hashas been donedone toto testtest thethe effectseffects of higher CO2CO, concentrationsconcentrations on forests or other natural plant communities overover extendedextended time time frames.frames. Therefore thethe net effect ofof climateclimate changechange onon forest growth andand yieldyield uncertain.uncertain. Sedjo and SolomonSolomon (1989)(1989) conclude that the phenomenonphenomenon of CO2CO, fertilization fertilization hashas notnot yet beenbeen detected in trees,trees, despitedespite extensive searches for it in the field and in growth chambers.chambers. 58 Climate Change, Forests and Forest Management

33,33. WHAWHAT T CHANGESCHANGES CANCAN BE EXPECTEDEXPECTED IN IN THETHE NANATURAL TURAL RANGES OF TREETREE SPECIESSPECIES AND AND PLANTPLANT COMMUNITIES DUE TOTO CLIMACL/MA TETE CHANGE?

When temperature and rainfall patterns change, the ranges of both animal andand plantplant speciesspecies change. change. As thethe Earth warms, species tendtend toto shiftshift their distributions toward higher latitudes andand altitudes. For eacheach 1°C1°C ofof warming, tree ranges inin the northern hemisphere have have the the potentialpotential to to expandexpand 100100 km northward whilewhile southernsouthern boundariesboundaries retreat.retreat. This is a process which has been trackedtracked since the last Ice Age (Davis 1989).

ThereThere isis ample evidenceevidence in in thethe fossilfossil recordrecord thatthat plants have undergone significantsignificant rangerange shiftsshifts in responseresponse to changingchanging climates. Analysis of fossil pollen datadata alsoalso providesprovides information onon the composition ofof pastpast vegetationvegetation (Brubaker(Brubaker 1975, SolomonSolomon and Bartlein 1992)1992) (Fig(Fig 6.1).6.1). During the Pleistocene interglacialinterglacial eras,eras, temperatures inin North AmericaAmerica were from 2°2° to 3°3° C higher thanthan theythey areare now.now. TreeTree species such asas sweetgum,sweetgum, LiquidambarLiquidambar styraciflua,styraciflua, andand OsageOsage orange, Maclura pomifera,pomifera, which today are considered typicaltypical components of forestforest vegetationvegetation inin thethe southeasternsoutheastern UnitedUnited States, occurredoccurred nearnear Toronto,Toronto, Canada.Canada. During the lastlast interglacial era, whichwhich ended moremore thanthan 100 000 yearsyears ago,ago, areas coveredcovered presentlypresently withwith boreal vegetationvegetation inin northwesternnorthwestern Europe, were predominantlypredominantly temperate.temperate. More recentlyrecently inin Sweden, the range of the birch,birch, BetulaBetula pubescens,pubescens, respondedresponded rapidly toto warmingwarming duringduring thethe firstfirst half of thethe twentiethtwentieth century byby expandingexpanding its rangerange northwardnorthward intointo thethe tundratundra (Peters 1990).

Shifts in thethe rangesranges of treetree speciesspecies couldcould bebe importantimportant forfor several reasons.reasons. FirstFirst,, there are indicationsindications thatthat climate could change faster than somesome treetree speciesspecies cancan respondrespond throughthrough migrationmigration.. Second,Second, newnew sitessites may may not not bebe edaphicallyedaphically suitablesuitable for thethe migrationmigration ofof species.species. Finally, future climateclimate zones,zones, Climate Change, Forests and ForestForest ManagementManagement 59

wl.1 _1~ ~CL wL" 0 '"z ~ > w ii Y s,• LL~ <1 CC k.0w U < L4w• ~ z Cc , w U rI Cr.~ O Z ~Cc •>S IDm ~ ~ U -'Ww Ir Z 1.0W ~wL.1 r 7 U 4 .4 ~CC 0 e.~ Uu , U z Cr~ O• 2 ,:tnocc2I~• 0 ~ > r X cr ~ cc~ 0-Z ci_~ ~ a w,w ..,, .1 a:o~ ,,w O0 --I~ ,I-- ,~- co~ ~LL_ ~ Uo x <1 0E1 ~ w 0 • •, • iD OU• O ~Ct r I ,JO CAMP 11 LAKE (SILT LOAM) AGE'GE (yeo,$)( yea. sI 'OOO3000 ~----'

8000

LOSLOSTT LAKLAKEE (SANO(SAND LOAM)LOAM)

300030oo l ---

0000

YELLOW DOGDOG PONDPOND (SAND)(SAND)

33000000

B8000OOO

l..l...l....LJ.-LI....L~I t Jt 0o 2020 40 '10 60 60 80 80 100 tOO `10"~ PERCEPERCENTAGENTAGE OF TOTAL POLLENPOLLEN

FigureFigure 6.1 -- Fossil pollen diagrams mademade fromfrom analysisanalysis of lakelake sediments inin the UpperUpper PeninsulaPeninsula of Michigan,Michigan, USA.USA. TheseThese datadata provideprovide cluesclues asas to to thethe composition ofof forests which occupiedoccupied thisthis area inin thethe pastpast (Source: Solomon and Bartlein 1992)1992).. leadingleading toto displaceddisplaced forestforest ecosystems willwill not bebe relatedrelated to current political boundariesboundaries andand (or)(or) landland use patterns (Izrael(lzrael et al 1990).

Studies havehave beenbeen done done which which predictpredict shiftsshifts in the naturalnatural rangesranges of plantplant ecosystemsecosystems (Fig(Fig 6.2) andand individualindividual treetree species whichwhich could result fromfrom temperaturetemperature andand moisturemoisture changes duedue toto atmosphericatmospheric levelslevels ofof GHGs.GHGs. Miller et alaJ 62 Climate Change,Change, ForeForestssts and ForeForestst Management

Legend LoblayLabially pinepine rangerange

~-lIGoin)1 (Gain)

[eH-2 (No(No change)change)

~ -33 (Loss)ILoss)

Figure 6.3 - Possible redistribution ofof loblollyloblolly pine, pine ,Pinus Pinus taedataeda inin thethe southeastern United States due to aa doublingdoubling ofof atmospheric atmospheric CO2CO 2 (Source -- MillerMiller etet al 1987).

0..)

lGOO~~ ~~-)A-~II~~--- ______I \ I , I \ / \

Figure 6.46.4 - ExamplesExamples of speciesspecies redistributionredistribution inin highhigh mountainmountain regionsregions duedue toto a 2°C2°C increaseincrease inin mean annual temperaturetemperature:: a a = mountains of eastern Africa resultingresulting inin aa relativelyrelatively smallsmall increaseincrease inin area andand bb = highlandshighlands ofof Uganda Uganda resultingresulting inin aa near near disappearancedisappearance of a high elevation vegetation zonezone (Source: Sombroek 1990).1990). Climate Change,Change, Forests andand ForestForest ManagementManagement 6363

Box 6.1 WillWill thethe futurefuture forestsforests ofof thethe worldworld be drier?

Plants may have reduced rates of transpiration inin anan atmosphere with elevated levels ofof CO2.CO,. The outcome could bebe aa world withwith reduced reduced cloudcloud formationformation andand lessless rain, according to aa reportreport byby thethe TerrestrialTerrestrial Initiative onon GlobalGlobal EnvironmentalEnvironmental ResearchResearch (TIGER) of the Natural Environmental Research CouncilCouncil of the UnitedUnited Kingdom.Kingdom.

Several research groupsgroups have successfully linked computer models of landland surfacesurface processes toto climateclimate predictionprediction models.models. AA simple climateclimate model predicted nearly 10% m9remore evaporationevaporation and 3% more rainfall overover the tropical rainrain forestsforests inin aa futurefuture highhigh CO2CO, environment. However,However. whenwhen thethe rainforest waswas describeddescribed more realistically, a newnew chain of events waswas started,started. leadingleading toto lessless water beingbeing availableavailable for cloudcloud formationformation and less evaporationevaporation and rainrain (WMO(WMO 1994). 64 Climate Change, ForestsForests andand ForestForest Management

Sea level rise, associatedassociated with risingrising temperatures,temperatures, couldcould effecteffect thethe distributiondistribution andand abundanceabundance ofof mangrove forests. These coastalcoastal forestsforests provide aa wealthwealth ofof woodwood andand nonnon woodwood forestforest products and services.services. InIn addition to meeting needs forfor wood products forfor the inhabitantsinhabitants of coastal zones inin the tropics, they provide a rich habitat for fisheries andand aquaculture. TheyThey alsoalso protectprotect coastalcoastal zoneszones from tropicaltropical storms and shoreline erosionerosion andand offeroffer breeding sitessites for aa largelarge numbernumber ofof wildlifewildlife species (FAO 1994,1994, Gable etet alal 1990).1990).

Future shiftsshifts in the naturalnatural rangesranges ofof treestrees andand forestforest communities could have both positive andand negativenegative effectseffects on supplies ofof lumber and other forest products,products, distance to markets, species diversitydiversity and susceptibilitysusceptibility to fire, pestspests and disease.

34. WHAWHAT T IS THETHE LIKELIHOOD THATTHA T CLIMACLlMA TE CHANGECHANGE COULD THREATHREA TEN TEN SOMESOME SPECIES OR PLANTPLANT COMMUNITIES WITHWITH EXTINCTION?EXTINCTION?

The likelihood that plant oror animal species couldcould be lostlost duedue toto climate change isis uncertain.uncertain. Because ofof theirtheir mobility,mobility, animals are generally at less risk because theythey are able to dispersedisperse to habitats whichwhich areare moremore favourable.favourable. Plants, on the otherother hand, are stationary, andand must relyrely onon dispersaldispersal ofof seedsseeds from areas which are no longer favourable to new areasareas resulting inin a gradual shiftshift in thethe theirtheir naturalnatural ranges.ranges. During thethe Pleistocene glacial eraseras manymany treetree speciesspecies werewere lostlost from thethe boreal and temperate forests ofof EuropeEurope becausebecause they werewere unable to shift theirtheir rangesranges southwardsouthward duedue toto thethe presencepresence ofof the Alps,Alps, thethe PyreneesPyrenees andand otherother predominantlypredominantly east-westeast-west mountain ranges which served as a naturalnatural barrierbarrier to plantplant migration. Consequently, thethe forests ofof northernnorthern EuropeEurope contain considerablyconsiderably fewer speciesspecies than those which occuroccur atat equivalent latitudes inin AsiaAsia andand NorthNorth America.America. ClimaClimate te Change,Change, ForestsForests and Forest Management 65

InIn general, plant ecologists believe thatthat plant species with broad geographicgeographic rangesranges andand manymany populationspopulations willwill be the most likelylikely toto survivesurvive climateclimate change.change. Examples includeinclude species suchsuch asas PinusPinus sy/vestris,sylvestris, whichwhich occurs fromfrom western Europe toto Siberia,Siberia, Popu/usPopulus tremu/atremula andand P.P. tremu/oides,tremuloides, bothboth of which have transcontinental distributions. Rare or geographically restrictedrestricted species wouldwould be at greater risk ofof extinction. ThisThis is is especially especially truetrue ofof speciesspecies restricted to highhigh elevation zones whichwhich would ultimately bebe unable toto shift their ranges furtherfurther upslopeupslope inin responseresponse to to a a warmer warmer climate. climate. An example isis thethe Fraser oror southernsouthern balsam fir,fir, AbiesAb/es fraseri, a tree whose natural rangerange is restricted to the highest elevations of sixsix areasareas inin thethe SouthernSouthern AppalachianAppalachian Mountains inin the United States (Fig 6.5).6.5). AnotherAnother categorycategory ofof plantsplants which areare at some riskrisk of extinction are those with heavyheavy seedsseeds which are not readilyreadily dispersed.dispersed.

Figure 6.5 .- A forest ofof. Ab/esAbies fraserifraseri andand PiceaPicea rubens straddles thethe highest ridgesridges inin the BlackBlack MountainsMountains of NorthNorth Carolina,Carolina, USA.USA. Forests suchsuch asas thesethese wouldwould be unable toto shift their rangesranges upslopeups lope inin response toto a warming climate.climate. 66 Climate Change, Forests andand Forest ManagementManagement

Other ecologists argueargue that that thethe riskrisk ofof extinction of plantplant species and resultant loss of biodiversitybiodiversity isis minimalminimal becausebecause plants possess geneticgenetic variationvariation whichwhich allowsallows themthem toto adapt to changingchanging environmentalenvironmental conditions. GeneticGenetic variationvariation isis aa prerequisite forfor evolution and a powerful mechanismmechanism which allows bothboth animalsanimals andand plantsplants toto changechange andand adaptadapt (Eriksson(Eriksson et al 1993).1993).

35. HOW MIGHTMIGHT CLIMATECL/MA TE CHACHANGE NGE INFLUENCEINFLUENCE THETHE INCIDENCE AND INTENSITYINTENSITY OFOF WILDFIRES?WILDFIRES?

As the structure, compositioncomposition andand biomassbiomass of forests respond to changingchanging climate, so will thethe behaviourbehaviour of firefire (Fosberg(Fosberg et al 1990).1990). SomeSome expected expected changes changes includeinclude increasesincreases in thethe frequency andand severityseverity ofof fires and aa lengtheninglengthening of firefire seasons in areas whichwhich are already prone toto fire events.events.

Some tropicaltropical rain forests are subject to periodicperiodic episodesepisodes of prolonged droughtsdroughts suchsuch asas thosethose caused byby the ElEl NiñoNifio Southern Oscillation (EN(ENSO). SO) . These droughts can drastically change thethe fuel conditions and flammabilityflammability of the vegetation. Once precipitationprecipitation falls below 100100 mmmm perper month, andand periodsperiods of twotwo oror more more weeksweeks withoutwithout rain occur, the forestforest vegetation sheds its leavesleaves progressivelyprogressively withwith increasingincreasing drought stress.stress. In addition, thethe moisture content of surfacesurface fuels isis lowered,lowered, whilewhile fallenfallen woodywoody materialmaterial andand looselyloosely packed leafleaf litter contributescontributes to thethe build-upbuild-up andand spreadspread ofof surface fires.fires. Aerial fuels such asas desiccateddesiccated climbersclimbers andand lianas become firefire ladders leadingleading toto crown firesfires (Goldammer(Goldammer and Seibert 1990). ItIt is is thisthis sequencesequence of events which setset thethe stage for thethe catastrophiccatastrophic firesfires whichwhich occurredoccurred inin EastEast Kalimantan, IndonesiaIndonesia during during 1982-83 1982-83 andand resulted in thethe destructiondestruction of over 3.5 millionmillion haha ofof primaryprimary andand secondarysecondary moist forest. SomeSome globalglobal circulationcirculation modelsmodels (GCM)(GCM) predict increasedincreased drought episodes in some tropical forestsforests.. Consequently the incidence of large wildwildfires, fires, suchsuch asas the ones which occurredoccurred inin EastEast Kalimantan,Kalimantan, couldcould increase.increase. Climate Change, Forests and Forest Management 67

Certain tropicaltropical rain forests, especiallyespecially thosethose in thethe sub-sub equatorial tropicstropics (from(from 1010 to 23°23° latitude)latitude) areare subjectsubject to hurricanes. DamageDamage associatedassociated with thesethese stormsstorms promotespromotes invasion ofof vines, which cancan contributecontribute toto foliarfoliar biomassbiomass accumulation onon soil surfacesurface openings,openings, particularlyparticularly duringduring occasional dry spells.spells. This results in fuelfuel loadingsloadings that cancan lead toto firesfires (Mueller-Dombois(Mueller-Dombois and Goldammer 1990).

Fuel accumulationaccumulation resultingresulting fromfrom thethe directdirect effectseffects of tropical storms can also increaseincrease the hazardhazard of wildfire.wildfire. InIn 1988, Hurricane GilbertGilbert sweptswept across partpart of Mexico'sMexico's YucatanYucatan Peninsula and damaged overover 11 million ha of tropicaltropical forests.forests. The volumevolume ofof combustible fuelfuel created by thethe debris increased thethe riskrisk of of wildfire.wildfire. DuringDuring thethe followingfollowing year,year, overover 120,000 haha ofof Mexico'sMexico's largest largest area area ofof tropicaltropical forestforest burnedburned (Ciesla 1993).1993). OneOne of thethe moremore uncertain effects ofof predictedpredicted climate change is thethe possibility of an increased frequency and intensityintensity ofof tropicaltropical storms.storms. ThisThis would would increase increase thethe levelslevels ofof combustible fuels.

In some remoteremote forestforest areas, lightning is a major cause ofof fire. A studystudy usingusing GCMsGCMs waswas donedone toto determine determine lightninglightning frequency for aa doubleddoubled CO,CO 2 climaticclimatic regime.regime. This studystudy predicts an increase inin lightninglightning frequencyfrequency atat allall latitudeslatitudes with a mean global increaseincrease ofof 26% (Fosberg(Fosberg etet al 1990).

36. WHAWHAT T AREARE THETHE EXPECTED EXPECTED EFFECTSEFFECTS OFOF CLIMACLlMA TETE CHANGE ON FORESTFOREST HEALTHHEAL TH INCLUDINGINCLUDING SUSCEPTIBILITY TO TO PESTSPESTS ANDAND DISEASEDISEASE OROR DECLINE?

An increaseincrease in insectinsect andand diseasedisease causedcaused losseslosses in forestsforests could become oneone ofof thethe first observedobserved effects ofof climateclimate change. EvidenceEvidence ofof thisthis cancan bebe foundfound inin thethe pest pest epidemics epidemics which areare the result ofof stressstress broughtbrought onon byby periodicperiodic droughtdrought or excessexcess rainfall.rainfall. Reviews byby KristiansenKristiansen (1993) andand Sauerbeck (1(1992) 992) ofof potential effects ofof climateclimate changechange onon 68 ClimateClima te Change, Change, Forests Forests and and ForestForest ManagementManagement pests and diseases inin agricultureagriculture provideprovide aa frameworkframework from which to identify potentialpotential forest sector effects.effects. TheyThey include both positivepositive andand negativenegative responses.responses.

Some anticipated negative effects on forest healthhealth are:are:

• InIn a given location,location, higherhigher temperaturestemperatures could result in moremore generations ofof insect pests per year, thus increasing theirtheir destructivedestructive potential.potential. This is especially truetrue forfor those insects which already have more than one generationgeneration a year.year. An exampleexample ofof a destructive forest insect of tropical forests whosewhose numbernumber ofof generationsgenerations could increase under aa warming scenario is the pine caterpillar, Dendrolimus punctatus,punctatus, anan importantimportant defoliator of tropical pinespines in southern China andand SoutheastSoutheast Asia (Fig 6.6)

• The ratiosratios of pestpest speciesspecies toto their naturalnatural enemies couldcould changechange inin favourfavour of the pests.pests. This would increaseincrease the reproductive potentialpotential of destructive pestspests and result inin higherhigher levelslevels of damage.damage.

• Increased climaticclimatic anomalies areare predictedpredicted toto occur as partpart ofof climateclimate change.change. A higherhigher incidenceincidence ofof droughts,droughts, storms,storms, deepdeep freezefreeze events or periodsperiods ofof excessexcess rainfallrainfall will putput additional stresses on trees and forests making them moremore susceptible to attackattack byby pestspests andand disease. ClimaticClimatic anomalies anomalies maymay also also increaseincrease the sensitivitysensitivity of treestrees toto airair pollutionpollution frornfrom anthropogenic sources.sources. Episodes ofof forestforest decline may also increase. TheseThese are the result of a complexcomplex interactioninteraction of forests with climate,climate, site, pestspests andand diseasedisease and,lInd, inin manymany cases,cases, human activities (Mueller-Dombois 1992). Examples include diebacks of MetrosiderosMetrosideros C//mateClimate Change,Change, ForestsForests andand ForestForest ManagementManagement 69

Figure 6.6 -- IInsectsnsects such as thethe pinepine caterpillar,caterpillar, DendrolimusDendrolimus punctatus, a destructivedestructive defoliator of tropicaltropical pinespines inin SoutheastSoutheast Asia, cancan undergoundergo additionaladditional generationsgenerations in warmerwarmer climates.climates. 70 Climate Change, Forests and Forest Management polymorpha in the HawaiianHawaiian Islands,Islands. USA,USA. Azadirachta indica in thethe Sahel regionregion ofof Africa.Africa, Acacia nilotica in the Sudan and Eucalyptus spp in AustraliaAustralia andand SouthSouth AmericaAmerica (Ciesla(Ciesla andand Donaubauer 1994).

* Widening carbon/nitrogen ratios in trees due to elevated levels of CO2CO 2 could increaseincrease foliagefoliage consumption by insects as has been demonstrated in laboratory studies. For example,example. Lincoln etet al (1984) showedshowed that feeding rates of lepidopterouslepidopterous larvaelarvae roserose withwith

corresponding increases in atmosphericatmospheric CO2.CO 2 , Forest defoliators such as the spruce budworms.budworms, Choristoneura spp.,spp.. in North America and pine caterpillars, Dendro/imusDendrolimus spp. in Asia could be similarlysimilarly affected.affected. AsAs aa resultresult outbreaks could causecause more severe defoliation. More recently Lincoln (1993) showedshowed similarsimilar feeding responsesresponses fromfrom larvaelarvae representing another group of foliagefoliage feedingfeeding insects; pinepine sawflies,sawflies. NeodiprionNe 0 diprion sp. (Hymenoptera: Diprionidae).

* A higherhigher incidence of insect andand diseasedisease outbreaks due to stressstress onon treestrees associatedassociated with climateclimate changechange will resultresult inin higherhigher levelslevels of combustiblecombustible fuelsfuels inin forestsforests increasingincreasing thethe risk ofof wildfires.wildfires. In thethe coniferconifer forestsforests ofof western North America,America. recent outbreaksoutbreaks of several species of bark beetles (Family Scolytidae) havehave increased thethe volumes ofof flammable fuels toto dangerouslydangerously highhigh levelslevels. These havehave resultedresulted inin large fires of highhigh intensity includingincluding the 1988 firefire inin YellowstoneYellowstone National Park inin thethe USA. TheseThese outbreaksoutbreaks areare believed toto be relatedrelated toto fire exclusion and not climate change,change. howeverhowever theythey serve as anan example ofof what couldcould happenhappen asas a result of Climate Change, Forests and Forest Management 71

predicted climate change (Hessburg et al 1994, USDA 1994)

Some possible positivepositive effects are:are:

• The higher growthgrowth rates which areare projected by some scientists, due toto warmerwarmer temperaturestemperatures and elevated CO2CO, levelslevels might might allowallow forests toto sustain higher levels of insectinsect andand diseasedisease damage withoutwithout reductions in growth andand yield.

• The increasedincreased vigourvigour of treestrees andand forestsforests growing inin elevatedelevated CO2CO, levels couldcould bebe moremore resistant to attackattack byby insectsinsects andand disease.disease.

• Elevated CO,CO2 maymay benefit plantplant healthhealth andand productivity byby alteringaltering thethe morphologymorphology andand physiology of plantsplants to the detrimentdetriment ofof diseasedisease causing organisms.organisms.

The hazardhazard of destructivedestructive insectinsect andand diseasedisease outbreaksoutbreaks inin tropical forestsforests isis believedbelieved toto bebe minimalminimal whenwhen comparedcompared toto temperate andand boreal forests becausebecause of their inherent diversity. WhileWhile thisthis maymay bebe truetrue inin tropical forestsforests ofof naturalnatural origin, it must bebe kept in mind thatthat many tropical countries, to meet their needsneeds for woodwood products,products, relyrely onon singlesingle speciesspecies plantations, oftenoften of fastfast growinggrowing exotics.exotics. Many ofof thesethese plantations are established with materialmaterial representingrepresenting aa narrow genetic base. TheseThese areare oftenoften unableunable toto adaptadapt toto changing changing environmental conditions. In 1990,1990, therethere werewere anan estimatedestimated 30.7 millionmillion haha ofof forestforest plantationsplantations inin 9090 tropicaltropical countriescountries (FAO 1993).1993). AA totaltotal ofof 23% 23% were were of of Eucalyptus Eucalyptus sppspp andand 10% were of various species of Pinus. TheseThese are subject to attack by aa varietyvariety of pests, many ofof whichwhich areare accidentally accidentally introduced. AnAn excellentexcellent reviewreview ofof forestforest insect insect and and diseasedisease plantation pests of thethe Asia-PacificAsia-Pacific RegionRegion is providedprovided byby Hutacharern etet alal (1990).(1990). ThisThis reviewreview clearlyclearly indicatesindicates that inin 72 Climate Change,Change. Forests and Forest Management tropical managed forests,forests, there is an ample numbernumber ofof insectinsect and disease pestspests whichwhich couldcould respondrespond toto changeschanges inin climate.climate. Climate Change, Forests and Forest ManagementManagement 73

Box 6.26.2.. Dieback ofof Juaiperus plocersprocera in Kenya - anan exampleexample of of the the effects effects of aof a regional climate change?change 7

DiebackDie back and and mortality mortality of Juniperus pracera,procera, an importantirnportant component of highland forests in KenyaKenya has been occurring at leastleast sincesince the earlyearly 1980's.1980's. In some places, up to 90% ofof thethe treestrees havehave been affectedaffected.. TheThe heaviest diebackdie back and mortality occursoccurs inin the drier low elevation forests. HigherHigher elevationelevation stands, whichwhich receivereceive moremore precipitationprecipitation andanp grow onon better soilssoils appearappear to bebe in aa reasonably goodgood state of health.health.

The factors responsibleresponsible forfor this conditioncondition are unknown. OneOne hypothesishypothesis isis that thesethese forestsforests havehave beenbeen stressed by a longlong termterm regional warming and" drying trendtrend whichwhich hasha~ affected the low elevationelevation sites to thethe point where they areare nono longerlonger suitablesuitable forfor this species (Ciesla etet alal 1994)1994).. As a result, the altitudinalaltitudinal rangerange of thisthis speciesspecies couldcould become moremore restrictedrestricted inin thethe future. 74 Climate Change, Forests and Forest Management

Chapter 77 HELPING FORESTSFORESTS ADAPT ADAPT TOTO CLIMATECLIMATE CHANGE

37.37, HOW CANCAN WEWE RESPOND RESPOND TOTO PREDICTEDPREDICTED CLIMATE CHANGE?

There are twotwo overalloverall approachesapproaches to respondingresponding to predictedpredicted climate change; adaptation and mitigation.mitigation. TheseThese approaches apply to all sectors involved in the climateclimate changechange issue.issue.

ADAPTATIONADAPTA TION isis concernedconcerned withwith responses to to thethe effectseffects of climate change. ItIt refersrefers to anyany adjustment, whether passive,passive, reactreactiveive or anticipatory thatthat cancan bebe adopted to ameliorateameliorate the anticipated expected or actual adverse consequences effectseffects of climate change.change. Adaptation alsoalso includesincludes taking advantageadvantage of anyany possiblepossible beneficialbeneficial effects suchsuch asas longerlonger growinggrowing seasons whichwhich might allow plantingplanting ofof certaincertain cropscrops atat higherhigher latitudes.

Many adaptation policies make goodgood sensesense regardlessregardless of climate change because present dayday climatic variability andand extreme climatic events,events, suchsuch asas droughts,droughts, severesevere stormsstorms andand floods already cause significantsignificant damage inin mostmost partsparts ofof the world. AdaptationAdaptation to to these these events events can can help help reduce reduce damagedamage inin the short termterm regardlessregardless of any longlong term changes in climate.

MITlGAMITIGATION TION oror "limitation""limitation" attemptsattempts toto addressaddress the causes ofof climate change.change. It achieves thisthis through actionsactions whichwhich prevent or retard increasesincreases in levels of atmosphericatmospheric GHGsGHGs byby limlimitingiting currentcurrent andand futurefuture emissionemission sourcessources andand enhancingenhancing potential sinks ofof GHGs.GHGs.

Both adaptation and mitigationmitigation strategiesstrategies shouldshould bebe considered in an iintegratedntegrated approach when designing responses to climate change. This chapterchapter addressesaddresses opportunitiesopportunities forfor helpinghelping forests adaptadapt toto climateclimate changechange whilewhile ChapterChapter 88 addressesaddresses mitigation options.options. Climate Change,Change, Forests and Forest Management 75

38, DO NANATURAL TURAL PROCESSESPROCESSES EXISTEXIST WHICHWHICH CAN HELP TREES AND AND FORESTS ADAPT ADAPT TO AA CHANGINGCHANGING CLIMATE?CLIMA TE?

Some populationspopulations of trees, because ofof theirtheir genetic variability, will bebe ableable toto survivesurvive thethe effectseffects ofof climateclimate changechange byby adjusting to thethe newnew conditionsconditions throughthrough acclimationacclimation ratherrather than by migrating to newnew locationslocations withwith climatesclimates similar similar toto thethe original habitathabitat.. AnotherAnother potentialpotential adaptiveadaptive mechanismmechanism isis thatt hat certain physiological and developmental traitstraits will undergoundergo permanent changes as a result of evolution.evolution.

In many cases, the boundariesboundaries of a species'species' rangerange maymay bebe aa consequence ofof factorsfactors operating inin additionaddition toto climateclimate.. OneOne of these factors isis competition.competition. InIn thethe northern hemisphere,hemisphere, the southern limits or lowerlower elevationelevation limits ofof thethe rangesranges ofof many speciesspecies areare determined determined by by competitive competitive relationships relationships with with species toto the southsouth oror atat lowerlower elevations.elevations. Thus, manymany northern species growgrow quite wellwell inin non-competitivenon-competitive situations far south ofot theirtheir naturalnatural ranges.ranges. If climateclimate changes,changes, thesethese species maymay bebe ableable toto persistpersist inin theirtheir original locationslocations if the better competitors dodo notnot invadeinvade immediately.immediately.

Often, reproductionreproduction andand seedlingseedling establishment isis moremore sensitive toto climate change thanthan isis the survivalsurvival of maturemature individuals. In such cases, adult individualsindividuals maymay persistpersist inin anan area longlong after regenerationregeneration hashas disappeared.disappeared.

39. HOW CANCAN FORESTFOREST MANAGEMENTMANAGEMENT HELPHELP FORESTSFORESTS ADAPT TO TO CLIMACLlMA TE TE CHANGE?CHANGE?

Good silviculturalsilvicultural practices, including maintenance ofof optimum stocking levels and selection of trees which areare bestbest adaptedadapted to existingexisting sitessites shouldshould ensureensure that forestsforests remainremain vigorousvigorous and relatively free of sitesite andand standstand relatedrelated stress.stress. These practices should help forests adapt to climateclimate change.change. 78 Climate Change, Forests andand Forest Management

feasible in mixed species plantings, which areare well adapted to local sites and climatic conditions and meet national needsneeds forfor forest products and services.services.

• Establish in-situin-situ andand ex-situ reserves ofof key forest species toto ensure thatthat aa gene poolpool ofof sufficient variability is available for tree improvement programmesprogrammes which which havehave thethe objective· of developingdeveloping varietiesvarieties capable of adapting to climateclimate change.change.

• Accelerate timber salvagesalvage and fuelfuel managementmanagement programmes toto reduce thethe hazard ofof wildfirewildfire inin forests, especiallyespecially those which havehave sufferedsuffered from highhigh levelslevels ofof pestpest andand diseasedisease damagedamage or forest declinedecline events.events.

• Design insect and disease monitoring programmes whichwhich are capable of detectingdetecting increases inin thethe occurrenceoccurrence andand intensityintensity of forest decline events andand inin thethe activityactivity ofof new pests and diseases (both indigenous andand introduced) inin addition toto thosethose whichwhich havehave historically caused losses.losses. Monitoring systems should also be capable of detecting changeschanges in the biology, ecologyecology andand naturalnatural ranges of pest species includingincluding timingtiming ofof key events in their life histories,histories, numbernumber ofof generations,generations, feedingfeeding patterns and pest/host interactions.interactions.

• Initiate research programmesprogrammes to determine effects of longlong termterm climateclimate changechange on thethe biology andand pest-disease/hostpest-disease/host interactions ofof traditional pestpest species.species. In addition, identifyidentify those speciesspecies whichwhich havehave a potential for becoming pests under a climate change ClimateC//mate Change, Forests and ForestForest ManagementManagement 79

scenario. Integrate new researchresearch informationinformation into operatingoperating programmesprogrammes asas soonsoon asas possible.possible.

• Conduct studies onon thethe effectseffects of fire,fire, insectsinsects and disease on biodiversity in terms of colonizers, successional andand climaxclimax species.species. Determine the degree ofof "disruptions""disruptions" inin the self repairing processprocess ofof vegetation systems due to climate change. ExamplesExamples include the inabilityinability of forestsforests toto re-invade re-invade burnedburned oror harvestedharvested areas, oror anan "arrested""arrested" succession, where scrub or lianaliana vegetationvegetation is nono longerlonger replacedreplaced byby forestforest..

• Initiate studies toto determinedetermine thethe effects ofof climatic anomalies on forest stability. 8080 Climate Change, ForestsForests andand Forest Management

CHAPTER 8 THE ROLE OF FORESTS AND FORESTRYFORESTRY FOR MITIGATING THETHE EFFECTSEFFECTS OFOF CLIMATECLIMATE CHANGE

4141., WHAT OPPORTUNITIESOPPORTUNITIES DODO FORESTSFORESTS ANDAND FOREST MANAMANAGEMENT GEMENT OFFER FORFOR MITIGATINGMITIGA TING THE EFFECTS OF PREDICTED CL/MACLIMA TE CHANGE?CHANGE?

ForestsForests provideprovide opportunitiesopportunities toto partiallypartially mitigatemitigate the predicted effects of climateclimate change.change. This This cancan bebe accomplished throughthrough three overall approaches:approaches:

Reducing sources of greenhousegreenhouse gases.gases.

Maintaining existing sinkssinks ofof greenhouse greenhouse gases.gases.

Expanding sinks ofof greenhouse greenhouse gases.gases,

Specific actionsactions underunder eacheach ofof thesethese approachesapproaches areare described in sections 8ASA -- 8CSC ofof thisthis chapter.chapter.

Two things mustmust bebe kept in mind when planning forestforest sector strategies and programmes designeddesigned to to mitigatemitigate effectseffects of climate change:change:

• Trees and forests areare onlyonly temporarytemporary carboncarbon sinks.sinks . When trees are harvested, burned oror die, some of the stored carbon is againagain releasedreleased into thethe atmosphere.atmosphere. Forest sector policies and strategies thereforetherefore shouldshould aim at prolonging the carbon storage capacitycapacity of trees and forests asas longlong asas possible.possible.

• Any forest sectorsector mitigationmitigation measures measures mustmust be be donedone inin concert with mitigationmitigation measuresmeasures in other sectors that contribute significantly toto thethe buildbuild upup ofof GHGs GHGs inin thethe atmosphere such as industry,industry, agriculture, transportation andand powerpower generation.generation. Climate Change, ForestsForests andand ForestForest ManagementManagement 81

42. WHATWHA T FEATURESFEA TURES SHOULD CHARACTERIZE ACTIONSACTIONS TAKEN TOTO MITIGAMITIGATE TE POTENTIALPOTENTIAL EFFECTSEFFECTS OFOF CL/MACLIMA TE CHANGE?

Regardless ofof whatwhat actions are taken to mitigate the predictedpredicted affects ofof climateclimate change,change, theythey shouldshould havehave thethe followingfollowing characteristics:

Ecologically Sustainable -- ActionsActions should provide for the longlong termterm needsneeds ofof both presentpresent and futurefuture generations.

Economically ViableViable - ProposedProposed actions shouldshould havehave lowlow startstart upup costscosts and and bebe sociallysocially integrative,integrative, buildingbuilding on local needs, life styles andand traditions.

Technologically Simple -- ActionsActions should bebe capable of being implemented successfullysuccessfully under under a a varietyvariety of conditions withwith aa minimum minimum ofof specialized specialized equipment,equipment, training oror procedures.procedures.

Adaptable - They should havehave sufficientsufficient flexibility toto adaptadaptto to changing economic, political, social, ecological and climatic conditions.conditions.

Socially Acceptable -- ProposedProposed actionsactions shouldshould havehave immediate andand clear benefits, especially to local residents.

43. WHATWHA T ADDITIONALADDITIONAL RESEARCH RESEARCH ISIS NEEDEDNEEDED TOTO MORE FULL YY UNDERSTAND THE POTENTIAL EFFECTSEFFECTS OFOF CL/MACLIMA TE CHANGE ON TREESTREES ANDAND FORESTS ANDAND TOTO DEVELOPDEVELOPADAPTA ADAPTATION TION ANDAND MITIGATION TACTICS?TACTICS?

There are manymany uncertaintiesuncertainties associated with allall aspects of thethe global climateclimate changechange issue.issue. With regardregard to forestsforests andand 82 Climate Change, Forests and Forest Management forestry there areare uncertaintiesuncertainties concerningconcerning the the impactimpact of possible climateclimate changechange onon forestforest ecosystems,ecosystems, thethe adaptationadaptation of forestsforests toto climateclimate changechange and the potential for mitigatingmitigating predictedpredicted adverse effectseffects of climate change by forests.

DuringDuring aa MinisterialMinisterial Conference on thethe ProtectionProtection of Forests in EuropeEurope heldheld inin Helsinki,Helsinki, FinlandFinland in in 1993,1993, the European statesstates and the European UnionUnion agreedagreed toto aa programmeprogramme ofof intensified researchresearch andand cooperationcooperation onon forestryforestry andand climate climate change.change. ThisThis programme provides aa comprehensivecomprehensive modelmodel forfor nationalnational and (or) regional effortsefforts and recommends the the followingfollowing lineslines ofof investigation:investigation:

* AchieveAchieve a greatergreater understandingunderstanding of the linkages between climate change and forestforest ecosystems,ecosystems, includingincluding feed-backsfeed-backs fromfrom ecosystemsecosystems toto the climate system.

* Quantify thethe role of forests,forests, forestforest soilssoils andand peatlands asas reservoirs,reservoirs, sinkssinks andand sources of carbon and understand the role of forests inin thethe global carbon cycle.cycle. ResearchResearch in this field may includeinclude the development of common methodologies forfor research, for nationalnational andand regional inventoriesinventories and the developmentdevelopment andand maintenance of data bases on reservoirs, sinks and sourcessources ofof carboncarbon inin terrestrialterrestrial ecosystems.ecosystems.

* Identify the geneticgenetic variability associatedassociated with regionally important treetree species and theirtheir ability to respond to changeschanges in climate andand increasedincreased concentration ofof carbon dioxide, and on thethe degree andand rate of evolutionaryevolutionary processesprocesses andand adaptation.

* Determine the dynamicdynamic equilibriumequilibrium of host-host parasite relationships in new climatic environments. Climate Change, Forests andand ForestForest ManagementManagement 83

• Study changeschanges inin soil formationformation processes,processes, including the mineralisationmineralisation of organicorganic mattermatter and leaching, in responseresponse toto climate change.change.

• Develop process-basedprocess-based predictive ecosystemecosystem models applicable on aa regionalregional scalescale whichwhich may be used in to integrateintegrate anticipatedanticipated changeschanges inin climate, interactions withwith air pollution, effects on forestforest ecosystems,ecosystems, fluxesfluxes ofof greenhouse greenhouse gases andand effects on forests and forest management.

• Define ways toto alter forest management systems toto optimiseoptimise adaptationadaptation to climateclimate change, ensure thethe health and functions ofof forests andand toto optimiseoptimise thethe sequestrationsequestration andand storage of carbon.carbon.

A conceptual plan for research in forest/atmosphericforest/atmospheric interactions in thethe UnitedUnited StatesStates hashas alsoalso beenbeen designeddesigned by USDA Forest Service (USDA 1988).1 988).

44. DO INTERNATIONALINTERNATIONAL AGREEMENTSAGREEMENTS EXIST WHICHWHICH ENCOURAGE DEVELOPMENTDEVELOPMt;NT AND PROTECTIONPROTECTION OF FORESTS TOTO ENHANCEENHANCE THEIR ABILITYABILITY TO MITIGAMITlGA TE THE EFFECTSEFFECTS OF CLlMACLIMATE TE CHANGE?

Several internationalinternational instruments and targetstargets havehave beenbeen developed which support large scale forestforest sectorsector developmentdevelopment as a meansmeans of mitigatingmitigating thethe effectseffects ofof predictedpredicted climateclimate change.

One ofof thethe first international accordsaccords onon climate changechange which referred directlydirectly toto forestry waswas thethe NordwijkNordwijk DeclarationDeclaration onon Climate Change which waswas developeddeveloped in 1989.1989. This declaration established aa targettarget ofof a net growth inin forestforest areaarea of 1212 millionmillion ha/yr by the beginning ofof thethe nextnext centurycentury.. AA 84 Climate Change, Forests and Forest Management follow upup workshopworkshop heldheld in Bangkok,Bangkok, ThailandThailand inin 19911991 concluded thatthat the prospect for attaining such a target was very limited (IPCC(lPCC 1992).

During the UnitedUnited NationsNations ConferenceConference on EnvironmentEnvironment and Development (UNCED),(UNCEDL heldheld inin Rio dede Janiero,Janiero, Brazil, a Framework ConventionConvention onon Climate Change,Change, designed toto control andand reducereduce futurefuture GHGGHG emissionsemissions waswas signed.signed. This convention was ratifiedratified by 100100 signatorysignatory countriescountries byby December 1994.

A non-legally binding authoritative statement entitled "Principles for aa GlobalGlobal ConsensusConsensus onon thethe Management, Management, Conservation and Sustainable DevelopmentDevelopment ofof all Types ofof Forests" was adoptedadopted atat thethe UNCED UNCED conference.conference. The statement stresses that forestforest landslands shouldshould bebe sustainablysustainably managed toto meet the social, economic,economic, ecological, cultural andand spiritual human needs of presentpresent andand futurefuture generations.generations. These principles and AgendaAgenda 2121, , an environmentalenvironmental programme for thethe 21st21 st centurycentury whichwhich was was also also promulgated promulgated atat UNCED, UNCED, propose forest conservationconservation measuresmeasures to conserveconserve carboncarbon pools and increaseincrease thethe securitysecurity of these pools.pools.

These statements which mustmust bebe translatedtranslated into actionaction programmes at the country and community levellevel inin orderorder toto bebe implemented. Several countries, includingincluding China,China, Denmark,Denmark, Finland, France andand ItalyItaly havehave developed developed strategicstrategic actionaction plans under thethe umbrella ofof thesethese internationalinternational agreements. France,France, for example,example, hashas targetedtargeted the the addition addition of of 3030 000 haha ofof afforestation annuallyannually forfor thethe nextnext 5050 years years andand the promotionpromotion of more durable uses ofof wood (e.g(e.g.. in construction) (Ministère(Ministere de l'Agriculture etet dede lala PbchePeche 1994).

International agencies,agencies, suchsuch asas FAO, can provide a wide rangerange of technical assistanceassistance and training related to climate changechange and identification of opportunitiesopportunities for forests to mitigatemitigate itsits effects. Climate Change, Forests andand ForestForest ManagementManagement 85

45. HOW CANCAN THETHE TROPICALTROPICAL FORESTSFORESTS ACTIONACTION PROGRAMME (TFAP)(TFAP) ASSIST ININ DEVELOPING FORESTFOREST SECTOR PROGRAMMES PROGRAMMES TO TO HELP HELP MITIGA MITIGA TE EFFECTS OF CLIMACL/MA TE CHANGE?

TFAP isis designed toto assist countries in the conservation andand sustainable useuse ofof tropicaltropical forestforest resources. TheThe planplan grewgrew out ofof parallelparallel effortsefforts sponsoredsponsored byby FAO,FAO. TheThe WorldWorld BankBank (WB),(WB). the United Nations DevelopmentDevelopment Programme Programme (UNDP)(UNDP) and the WorldWorld ResourcesResources InstituteInstitute (WRI).(WRll. The ProgrammeProgramme was formalized inin 1987 and strengthened inin 1991. LeadershipLeadership forfor the programmeprogramme isis housedhoused inin FAO.FAO.

TFAP isis aa country-drivencountry-driven approach to forestforest resourceresource planningplanning and management.management. TheThe processprocess involves aa high level ofof participation by locallocal people and non-government organisations,organisations, is multidisciplinarymultidisciplinary andand intersectorial.intersectorial. TFAP begins withwith the formulation or revision of a long term forest policy and strategy andand the developmentdevelopment of aa nationalnational forestforest plan. This processprocess can facilitate thethe integrationintegration ofof clinnate climate change considerations intointo the development and implementation ofof longlong rangerange forest sectorsector policies,policies, strategiesstrategies and plans. 86 C//mateClimate ChangeChange,, ForestsForests andand ForestForest Management

8A REDUCING SOURCES OF GREENHOUSEGREENHOUSE GASES

46. WHAT ACTIONS CAN BE TAKENTAKEN TO REDUCEREDUCE THE CURRENT RARATES TES OFOF TROPICALTROPICAL DEFORESTATIONDEFORESTA TlON AND HOW MIGHT THIS AFFECTAFFECT EMISSIONSEMISSIONS OFOF GHGSGHGS FROM FORESTS?

Arresting the currentcurrent ratesrates ofof deforestationdeforestation requiresrequires actionsactions which reducereduce pressures toto convertconvert forest lands toto other uses and to protect remainingremaining forests soso that theythey cancan bebe managedmanaged on a sustainable basis.basis. MostMost deforestationdeforestation isis causedcaused byby the expansion of agriculture.agriculture. This isis in direct responseresponse to expanding human populationspopulations andand economiceconomic development.development. Programmes aimedaimed at at reducingreducing deforestationdeforestation must.must, therefore.therefore, be accompaniedaccompanied byby efforts toto increaseincrease productivityproductivity andand sustainability ofof existingexisting agriculturalagricultural landslands soso that productionproduction keeps pace withwith increasingincreasing demands.demands. In manymany cases,cases. deforestation hashas been consideredconsidered as as beingbeing onlyonly aa forest sectosectorr problem when in reality itit isis aa multisectoralmultisectoral issue.issue.

According to oneone estimate,estimate, as much as 80%80% of forest clearingclearing for shiftingshifting andand sedentarysedentary agricultureagriculture can bebe eliminatedeliminated byby substituting sustainablesustainable cropping systems (Lashof and Tirpak (1989). TheyThey suggestsuggest thethe followingfollowing actionsactions forfor reducingreducing thethe expansion ofof agriculture into tropical forests:forests:

*• Introduce crop mixes, planting andand management systems and improved genetic strains of cropscrops to increase productivity perper unitunit areaarea on existing agricultural lands.lands. InIn somesome cases,cases. investment inin fertilizers, irrigation systemssystems andand capitalcapital (high(high input systems)systems) will be neededneeded toto achieve adequate agricultural intensificationintensification and sustainability. Climate Change, Forests and ForestForest ManagementManagement 87

• Conduct research onon useuse ofof low external input cropping systems where high inputs are notnot feasible.

• Develop opportunities for raisingraising ofof cashcash cropscrops as well asas subsistencesubsistence crops so thatthat farmersfarmers can acquire needed cashcash toto invest in fertilizers, irrigation equipmentequipment and other technologies.technologies.

• Intensify managementmanagement of existing pasturepasture landslands to increase site productivity through the introduction ofof optimizedoptimized foragingforaging strategies,strategies, fertilization, mechanisation and improved livestock management.management.

• Focus agricultural developmentdevelopment onon sitessites with adequate non-forest soilssoils suchsuch asas savannah,savannah, pasture and under-utilised cropcrop lands.lands.

The opportunities for implementingimplementing these and otherother optionsoptions should be determined through the development of strategicstrategic landland and resource management plans at the national level.level.

47. WHAWHAT T CAN BE DONE TOTO REDUCEREDUCE THETHE FREQUENCYFREQUENCY AND SCALE OF FORESTS AND SAVANNASAVANNA WOODLAND CONSUMEDCONSUMED BY BIOMASS BURNING?

Most fires which occuroccur inin thethe savannassavannas and woodlands of the tropics areare prescribed or intentional fires.fires. These are set byby local residents who useuse firefire to clear land, dispose of agricultural residues, improveimprove thethe quality of forageforage for livestock oror toto drivedrive gamegame animals. TheseThese practicespractices areare basedbased on traditions which areare often thousands of years old. UnlessUnless there are massive changes in agricultural and range management practicespractices inin these countries in the nearnear future,future, these practices and resultantresultant carbon emissions will continue in the future. 88 Climate Change, ForestsForests andand Forest Management

Prescribed firesfires often escape andand burn over areas whichwhich are not intended to bebe burned.burned. TheThe numbernumber andand areaarea burnedburned by wildfires or unintentional fires cancan bebe reducedreduced throughthrough implementationimplementation of integratedintegrated firefire managementmanagement programmes.programmes. While thethe primary benefit of thesethese programmesprogrammes is thethe protection of forest andand other wildlandwildland resourcesresources from from wildfire, wildfire, theythey will alsoalso reducereduce carboncarbon emissions.emissions.

The elements of an integratedintegrated wildfire management programme include fire prevention,prevention. presuppressionpresuppression planningplanning (fire detection, firefire dangerdanger ratingrating basedbased on local fire weatherweather and fuel conditions (Fig 8.1),8.1), training and equipping ofof fire brigades) andand suppression.suppression, the the actual actual fightingfighting of forestforest andand woodland fires.

Prevention should be directeddirected towardtoward specific groupsgroups ofof peoplepeople which cause wildfires. ForFor example,example, inin Indonesia,Indonesia. woodlands in severalseveral national parksparks areare underunder a a highhigh riskrisk ofof wildfirewildfire because ofof agricultural burning byby neighbouringneighbouring farmers.farmers. This was one of thethe targettarget groupsgroups identified as part of a projectproject funded throughthrough thethe FAOFAO TechnicalTechnical CooperationCooperation ProgrammeProgramme (TCP)(TCP) in in wildfire wildfire management.management. The subsequent fire prevention programme specifically addressed this group.group. Another keykey aspect of preventionprevention isis fuelsfuels management. management. This includesincludes establishment of fuelfuel breaksbreaks in strategic locations and periodic use of prescribedprescribed burningburning to reducereduce volumes of combustiblecombustible fuels. AA relativelyrelatively simple simple procedureprocedure suchsuch asas teachingteaching farmersfarmers how to constructconstruct firefire breaksbreaks aroundaround pasturespastures or fieldsfields whichwhich are to bebe burnedburned cancan preventprevent prescribedprescribed fires fromfrom escapingescaping and burning surroundingsurrounding forests andand woodlands.woodlands.

When designingdesigning wildfire managementmanagement programmes,programmes, it isis necessary toto have an understanding ofof the ecological role of natural fires in the areas which are to be protected. In many semi·aridsemi-arid ecosystems, firefire playsplays a key role in plant succession. Fire exclusion cancan resultresult in thethe establishment ofof moremore vegetative biomass thanthan thethe sitesite isis capablecapable ofof carrying.carrying. This ClimateClimate Chango,Change, Forests and Forest Management 89

Figure 8.18.1 - AA foresterforester inin Mexico'sMexico's Yucatan Yucatan Peninsula Peninsula assessesassesses forest fuels.fuels. KnowledgeKnowledge ofof fuel fuel conditionsconditions isis anan importantimportant factorfactor in in planning forest firefire managementmanagement programmes.programmes. 90 Climate Change, ForestsForests andand ForestForest Management vegetation subsequently becomesbecomes susceptible susceptible to to attackattack by insects, diseasedisease and otherother damagingdamaging agentsagents resultingresulting in excessively high accumulations of combustible fuels. Consequently, when a wildfire doesdoes occur after aa longlong periodperiod of firefire exclusion,exclusion, it burnsburns withwith greatergreater intensityintensity andand cancan bebe more damaging (Hessburg(Hessburg et et alal 1994,1994, USDA 1994)1994)..

48. HOW CAN INCREASING THETHE EFFICIENCY OFOF BURNINGBURNING FUEL WOODWOOD ANDAND OTHEROTHER BIOFUELSBIOFUELS REDUCEREDUCE EMISSIONS OF GHGS?

Fuelwood and other biofuels, including charcoal, crop residues, animal dungdung andand other forms of biomassbiomass are used in manymany parts of the world forfor cooking,cooking, heatingheating andand processing of raw materials at thethe householdhousehold levellevel (Fig 8.2)8.2).. Biofuels areare presently thethe fourth most importantimportant source of energyenergy in the world with fuelwoodfuel wood andand charcoal consumption alone accounting forfor 10% of overall world energy consumptionconsumption.. In developing countries, biomassbiomass is the dominant energy source. For example,example, inin Ethiopia,Ethiopia, biofuelsbiofuels account account forfor overover 93%93% ofof the national energyenergy supplysupply (Karekezi(Karekezi 1994).1 994). Use of householdhousehold biofuels isis estimatedestimated toto contributecontribute betweenbetween 22 andand 7%7% of the annual emissions of GHGsGHGs from humanhuman sources.sources. Fuelwood and other biofuels are also usedused inin manymany developing countries to support manymany smallsmall andand mediummedium scalescale rural industries suchsuch as charcoalcharcoal kilns,kilns, bakerybakery ovens,ovens, brickbrick kilns,kilns, tobaccotobacco andand coffeecoffee processing plants.

In most cases,cases, household biofuels are converted into energyenergy using methods which areare inefficient andand produceproduce aa low energyenergy output. They also produce aa high GHG outputoutput per unit of energy produced.produced. The use ofof moremore efficientefficient combustioncombustion systems provides an opportunity toto increaseincrease energy output andand reduce thethe per unitunit output ofof GHGs.GHGs. TheyThey provide provide an an addedadded benefit of reduced pressure on existingexisting biofuel resources. ThisThis is especially importantimportant inin many semi-aridsemi-arid regions where rapidlyrapidly Climate Change, Forests and Forest ManagementManagement 91

FigurFiguree 8.28.2 - FuelvvoodFuelwood isis takentaken fromfrom a forest plantation to10 aa villagevillage in Indonesia.Indonesia. Rural people inin ddevelopingeveloping cocountriesuntries rely heavily onon fuelfuelwood wood forfor cookingcooking andand heating.heating. More efficientefficient useuse ofof biofuelsbiofuels offers anotheranother opportunityopportunity toto reduce reduce GHGGHG emissions.emissions. 92 Climate Change, Forests and Forest Management

expanding populations areare putting increasedincreased pressurepressure on biofuel resources, leadingleading toto deforestationdeforestation andand desertification.desertification.

The introductionintroduction of moremore efficientefficient cookingcooking stovesstoves andand industrialindustrial processes couldcould reduce fuelwoodfuelwood requirements by 25-70% atat aa low investment cost. ThisThis cancan also contributecontribute toto reduced GHGGHG emissions. emissions. InIn addition,addition, thethe useuse ofof betterbetter qualityquality biomass in terms of size, moisture content andand heatingheating value,value, ifif available, can contributecontribute to heating efficiencies and reduced GHG output.output. InIn orderorder to achieve maximum benefits from more energy efficient technologies, theirtheir introduction must bebe accompanied by adequateadequate trainingtraining in their useuse suchsuch asas programmes whichwhich areare offered by NGO'sNGO's such as thethe Foundation for WoodstoveWoodstove Dissemination.Dissemination.

49.49. HOW CAN USE OFOF WOODWOOD ANDAND OTHEROTHER "BIOFUELS"HBIOFUELSH IN PLACE OF FOSSIL FUELS HELP REDUCE LEVELS OFOF GHGS IN THETHE ATMOSPHERE?

The substitution ofof biomassbiomass inin place ofof fossil fuelsfuels asas aa modern energy sourcesource hashas thethe potentialpotential toto dramaticallydramatically change the global warming implications ofof risingrising energyenergy consumption, especially in tropicaltropical countries.countries. Opportunities existexist to useuse large quantities of agricultural andand forest residuesresidues that wouldwould otherwise gogo to waste.waste. There are alsoalso opportunitiesopportunities toto develop biomass crops primarily for energyenergy production.production. If produced efficiently,efficiently, "biofuels" couldcould supplysupply aa significantsignificant proportion ofof commercialcommercial energyenergy demanddemand in comingcoming decades.decades.

The benefits of bioenergy utilization go beyond substitution ofof

fuel sources. BiofuelsBiofuels cancan notnot only only help help to to close close the the CO2 CO 2 cycle and reduce GHGGHG emissions,emissions, but biomass plantations, established onon presently fallow lands,lands, wouldwould alsoalso expandexpand carbon reservoirs. In addition, the substitution ofof domesticallydomestically produced biomass couldcould also contributecontribute toto improveimprove thethe balancebalance of payments of energy poor countries. OtherOther benefitsbenefits includeinclude Climate Change, Forests and Forest Management 93 new job opportunitiesopportunities inin ruralrural areasareas and a decentralization of energy resources.resources.

The most obvious opportunities for useuse of biomassbiomass for energy involveinvolve agricultural and industrialindustrial wastes.wastes. InIn Indonesia,Indonesia, forfor example, large quantities of woodwood wasteswastes fromfrom logginglogging andand wood processingprocessing operations are piled and burned, used for landfilllandfill or dumped into rivers and the ocean. TheseThese materialsmaterials are presently considered to bebe a waste disposal problemproblem ratherrather than aa sourcesource ofof energy.energy. It isis estimatedestimated thatthat inin Indonesia,Indonesia, wood wastes from sawmillssawmills andand plywoodplywood plantsplants wouldwould bebe sufficient to produce 11 000000 megawatts ofof electricity.electricity. ThisThis isis equivalent toto 20-30% ofof thethe energy energy presentlypresently derivedderived fromfrom fossil fuels. Sugar canecane andand rriceice wasteswastes offeroffer similar opportunitiesopportunities.. Some agricultural and industrial wasteswastes cancan also be incorporated into the soilsoil toto increaseincrease carboncarbon storage.storage.

The potential for biomassbiomass utilization goesgoes beyond the useuse ofof waste products. TropicalTropical forestryforestry plantations plantations havehave recordedrecorded yields equequivalentivalent toto more thanthan 15 tons ofof carboncarbon perper haha perper year. EvenEven assuming modest growth rates, these plantations could make aa significantsignificant contribution to bothboth energyenergy suppliessupplies and temporary carbon storage if establishedestablished overover largelarge areasareas (Trexler et al 1992).

50. HOW CANCAN MOREMORE EFFICIENTEFFICIENT TIMBERTIMBER HARVESTINGHARVESTING REDUCE GHGGHG EMISSIONSEMISSIONS FROM FORESTS?

Uncontrolled timber harvesting operationsoperations resultresult inin excessiveexcessive soil disturbance, logging residuesresidues and damaged residual treestrees..

This causes increased emissions ofof CO2CO 2 and otherother GHGsGHGs andand decreases the the capacitycapacity ofof the residualresidual forest toto sequestersequester carbon (Pinard(Pinard 1994).1994). Timber harvestingharvesting is aa damagingdamaging process, no matter how well planned and carefully implemented.implemented. HoweverHowever there areare certain planning andand operational practices which cancan bebe implemented to reducereduce the disruption of forestforest processes.processes. 94 Climate ChangeChange,, Forests and Forest Management

Good timbertimber harvestingharvesting beginsbegins withwith thethe developmentdevelopment ofof forestforest management and harvestharvest plans. TheThe forest managementmanagement planplan includesincludes maps and descriptions ofof areasareas to bebe harvested, areasareas toto bebe protected,protected, contractualcontractual informationinformation andand otherother generalgeneral policies. Harvest plans describe inin detaildetail thethe harvestingharvesting operationoperation..

Many ofof the reductionsreductions in logging damage which areare characteristic ofof well managedmanaged forestsforests areare thethe resultsresults of careful harvest planning (Dykstra andand HeinrichHeinrich 1992).1992). TheseThese environmental benefits areare generally not expensiveexpensive andand maymay actually increase the efficiency ofof the harvesting operationoperation andand reduce costs.

Several procedures cancan significantlysignificantly reducereduce logginglogging damage.damage. Pre-felling ofof vines is oftenoften recommendedrecommended where they bindbind trees together to reducereduce felling damage. DirectionalDirectional felling isis recommendedrecommended in in areasareas whichwhich are toto bebe selectivelyselectively logged.logged. This will reducereduce damagedamage toto potentialpotential future cropcrop treestrees andand facilitate skidding.skidding. Yarding alsoalso deserves aa great deal of consideration becausebecause it it can causecause damagedamage to soilssoils andand residual trees.trees. Exposed soilssoils are subject to erosionerosion andand leaching ofof organic mattermatter including carboncarbon.. YardingYarding damagedamage can be reduced by restrictingrestricting bulldozersbulldozers to designateddesignated skidskid trails and maximizing log winching distances. SoilSoil damagedamage cancan be further minimized by use of yarding systems which movemove logs suspendedsuspended in thethe air (eg skylines, helicopters andand balloons).

Increased utilizationutilization ofof felled trees will result inin a reduction of overall land area whichwhich needsneeds toto bebe logged.logged. AA studystudy byby FAOFAO (Dykstra 1994)1994) revealedrevealed that inin severalseveral tropical countries, lessless than 50%50% ofof thethe woodwood inin thethe main main stemsstems ofof tropical tropical treestrees felled for harvestharvest isis actuallyactually utilized.utilized. The remainder of thethe main stem and thethe otherother partsparts ofof the tree are leftleft in the forest as logging residues. ByBy comparison,comparison, thethe averageaverage fraction ofof thethe mainmain stemsstems utilizedutilized inin industrialindustrial countriescountries isis moremore thanthan 78%. Climate Change,Change, ForeForestssts and Forest Management 95

Post harvest practices such as removal of streamstream crossingscrossings which impedeimpede waterwater flow, proper slash disposal and treatmentstreatments to promote vegetation growthgrowth in in denudeddenuded areas willwill help promote recovery ofof harvestedharvested areasareas (Putz 1994).

An exampleexample of thethe benefitsbenefits ofof improved improved timbertimber harvestingharvesting techniques comes frofromm a study done in dipterocarp forestsforests in Sabah, Malaysia (Pinard 1994).1994). Normally,Normally, treestrees overover 6060 cmcm inin diameter at breast height (dbh)(dbh) are harvested and skiddedskidded toto landingslandings byby bulldozers.bulldozers. Approximately 88 toto 1515 treestrees perper haha are removed inin thisthis manner and upup toto 75% ofof thethe residualresidual treestrees suffer logginglogging damage.damage. Prior to logging,logging, thesethese forestsforests cancan store up to 330330 tC/ha.tC/ha. The harvesting operationoperation removesremoves about 80 tC/ha.tC/ha. Through the use ofof controlledcontrolled harvestingharvesting techniques, it hashas beenbeen demonstrated thatthat if damagedamage toto thethe residual stand stand can can bebe reducedreduced from from 40% 40% toto 20%,20%, thethe additional amount of carboncarbon remainingremaining in the residualresidual forest after 1010 yearsyears couldcould bebe overover 6565 tons/hatons/ha (Fig(Fig 8.3).

CoConventionalnventional logginglogging RReduced-impacteduced-impact logginglogging

Damaged Damaged treestrees trees

4111111111111Treetops

Residual ResidualResid ual forestforest forestforest 1E1ì 4111117mber ((120120 tonnestonnes Treetops 1185{1 85 tonnes cacarbon/ha)rbonJha) carbon/ha)carbon/hal Timber

Figure 8.38.3 - A A comparisoncomparison ofof residualresidual carboncarbon storagestorage betweenbetween conventional andand reduced impact logginglogging inin MalaysiaMalaysia (Source:(Source: PinardPinard 199411994) 9696 Climate Change, Forests andand Forest Management

88SB MAINTAINING EXISTING SINKS OF GREENHOUSE GASES

51,51. HOW CANCAN MANAGEMENTMANAGEMENT AND CONSERVATION OF NANATURAL TURAL FORESTS ENHANCEENHANCE THEIRTHEIR CAPACAPACITY CITY TO FIX AND STORE CARBON?

ImprovedImproved managementmanagement of natural forests can increaseincrease productivity andand carboncarbon storage potential through accelerated growth, maintenancemaintenance ofof optimum levels of stockingstocking andand protection from fire,fire, pestspests andand diseasedisease (See(See questionQuestion -40). There are many opportunitiesopportunities worldwide,worldwide, toto improveimprove thethe management ofof naturalnatural forests.forests. InIn the tropics,tropics, for example, an estimated 137137 millionmillion haha of logged forests could benefit from enrichment planting and regeneration because present selective logging practices have reduced longlong termterm productivityproductivity (Grainger 1989) (See(See questionQuestion 50).50).

The development and expansionexpansion ofof non-woodnon-wood forestforest products would provideprovide increasedincreased incentivesincentives toto maintain and protectprotect forests. This could havehave thethe addedadded desirabledesirable effecteffect ofof increased carboncarbon storage.storage. Examples ofof opportunities to develop non-wood forest products include production ofof latex,latex, nuts, resin,resin, mushrooms,mushrooms, wild meatmeat andand plantsplants ofof medicinalmedicinal value (Fig 8.4).

Establishment ofof reserved or protected forests, whichwhich areare excluded from timbertimber harvestingharvesting will also helphelp maintainmaintain existing natural forests asas carbon sinks, provided that they are protected fromfrom damagingdamaging effects ofof fire,fire, pests pests and and disease. disease. These forestsforests still provide many opportunities for management of non-timbernon-timber forestforest resources.resources. These includeinclude providingproviding habitat for wildlife,wildlife, establishmentestablishment of sitessites wherewhere rarerare oror endangered plantplant speciesspecies cancan bebe protected,protected, inin. situ Climate Change,Change, ForestsForests andand ForestForest ManagementManagement 97

Figure 8.4 - In Vietnam, aa womanwoman collectscollects resinresin inin aa pinepine plantation.plantation. Non-wood forest productsproducts cancan provideprovide economiceconomic incentivesincentives toto managemanage andand protectprotect forestsforests,, thus maintainingmaintaining their capacity to absorbabsorb and store carbon. 98 Climate Change,Change; Forests and Forest Management conservation of geneticgenetic resources, development ofof outdoor recreation opportunities, protection ofof soilsoil and water resources and gathering of non-wood products such as wildwild fruits andand mushrooms. SuchSuch forestsforests wouldwould probablyprobably provideprovide a limited carbon absorption potential however because theythey oftenoften contain large areas ofof maturemature forestsforests where carbon absorptionabsorption is roughly equalequal toto carboncarbon release.release.

52. WHAWHAT T USES OF FORESTS AND FOREST PRODUCTS ARE MOST DESIRABLEDESIRABLE FROMFROM THE STANDPOINTSTANDPOINT OFOF LONG TERMTERM CARBOIVCARBON STORAGE?STORAGE?

From the perspective ofof CO2CO, storage,storage, thethe most desirable uses of forest andand forest productsproducts are those which extend rotation ages and production of goodsgoods whichwhich areare durabledurable andand longlong lasting. This will allowallow forfor thethe carboncarbon to bebe storedstored inin thethe woody tissuetissue forfor asas longlong asas possible.possible. However local andand national needs for goodsgoods and services will prevailprevail overover globalglobal concerns for carbon sequestration. Therefore,Therefore, fromfrom thethe socio-socio economic standpoint, forests should be put to whateverwhatever usesuses are requiredrequired toto support national and locallocal needs,needs, providedprovided thatthat these uses areare sustainable.sustainable. If forests provideprovide for thethe needsneeds of people, thenthen there are built in incentives to managemanage them on a sustainable basis andand theirtheir probabilityprobability of long term survival and benefit isis increased.increased.

Conversion of trees into durabledurable products suchsuch asas furniture oror wooden structures will extendextend theirtheir carboncarbon sequestration.sequestration. Recycling of paper productsproducts will reduce thethe needneed for harvesting trees for manufacture into newnew paperpaper products.products. Climate Change, Forests and Forest ManagementManagement 99.9.9

SCSc EXPANDING SINKSSINKS OFOF GREENHOUSEGREENHOUSE GASESGASES

53.53, HOW MUCHMUCH CARBONCARBON CANCAN BEBE FIXED IN WOOD AND SOIL ONON AA PERPER HECTARE HECTARE BASISBASIS ININ FOREST FOREST PLANTA TIONS IN BOREAL, TEMPERA TE TE AND TROPICAL ZONES?

The rate of carboncarbon fixingfixing isis aa functionfunction ofof many many variables. variables. These include treetree species, growthgrowth rates, longevity,longevity, site,site, annual precipitation, lengthlength ofof growing season,season, rotation length,length, etc. Annual raterate of carboncarbon fixingfixing is highesthighest in young plantations.

Fixation rates for several tropicaltropical forest plantation speciesspecies over a given rotation areare summarizedsummarized by SchroederSchroeder (1991) (Table(Table 8.1).S.1 ).

TABLE 8.1

CARBON FIXATION RATESRATES FORFOR SEVERALSEVERAL TROPICAL FORESTFOREST PLANTATIONPLANTATION SPECIES SPECIES (Source: Schroeder 1991)1991)

Species Rotation Mean Above (Yrs)(Yrs) Ground CarbonCarbon Storage (Tonnes C/ha)

Pinus caribea 15 59 Leucaena sp.sp. 7-8 21-42 Casuarina sp.sp. 10 21-5521 -55 Pinus patula 20 72 Cupressus lusitanica 20 57 Acacia niloticani/otica 10-15 12-171 2-17 100 Climate Change, Forests and Forest Management

An overridingoverriding factor in afforestationafforestation or reforestation isis toto match the tree species,species, and provenance to to thethe sitesite onon whichwhich it isis toto bebe planted.planted. In addition, speciesspecies should bebe selectedselected which meetmeet thethe objectivesobjectives ofof the plantation and are acceptableacceptable to thethe peoplepeople of the locality. If these conditions are met, and with properproper managementmanagement andand protection,protection, t'nethe plantations should be assured ofof high rates ofof survival, good growth andand will meetmeet thethe objectivesobjectives forfor whichwhich theythey areare planted,planted, includingincluding sequestration of carboncarbon (Fig(Fig 8.5).8.5).

54.54, HOW MUCHMUCH ADDITIONALADDITIONAL AREAAREA OFOF FORESTFOREST PLANTA TIONS TIONS WOULDWOULD BEBE REQUIREDREQUIRED TO FULLYFULL Y OFFSET PRESENTPRESENT ANNUALANNUAL INCREASES IN GREENHOUSE GASGAS LEVELS FROM ALL SOURCES?SOURCES?

A numbernumber of studiesstudies have been conductedconducted toto estimate forest area requiredrequired to to offsetoffset variousvarious COCO2emission 2 emission goalsgoals.. AA studystudy by Sedjo and Solomon (1989)(1989) indicates that thethe currentcurrent annualannual increase inin atmosphericatmospheric carbon could be sequesteredsequestered forfor about 30 years in approximatelyapproximately 465 million ha ofof plantation forests. This wouldwould requirerequire an increase ofof moremore thanthan 10% in thethe current area ofof forests on the earth's surface. It would alsoalso represent anan increaseincrease ofof more thanthan four times thethe presentpresent plantation area in the world.world. This estimate is basedbased on the assumption of an average annualannual growth growth ofof 1515 m3/ha/yr. An annual growth raterate of 5 mJ/ha/yrm3/ha/yr is moremore realisticrealistic forfor plantations in the borealboreal andand temperatetemperate zones and for manymany tropical areas. Therefore thisthis estimate may bebe highlyhighly conservative.

Calculations areare presented byby Grainger (1990) forfor severalseveral afforestation scenarios.scenarios. TheseThese suggestsuggest thethe following:following:

*• Planting 6060 million ha per year for 1010 yearsyears would establish sufficient forestforest areaarea to absorbabsorb

2.9 GtCGtC perper year,year, thethe netnet incrementincrement ofof CO2 CO 2 from allall sources.sources. ClimateC//mate Change~Change, Forests and Forest ManagementManagement 101

Figure 8.58.5 -- PlantationsPlantations ofof fastfast growing trees, suchsuch as this plantation of AnusPinus radiataradiata in ChileChile,, can absorbabsorb atmosphericatmospheric CO,CO 2 whilewhile providing aa wide rangerange ofof woodwood andand non-woodnon-wood productsproducts andand services. 102 Climate Change, Forests and Forest Management

• Planting 2020 million ha perper yearyear beginningbeginning in 1990 wouldwould achieveachieve aa carboncarbon absorptionabsorption equalequal to thethe currentcurrent netnet annualannual CO, contribution byby the year 2020.

• Planting 22 millionmillion haha per yearyear forfor 3030 yearsyears would establish a forestforest thatthat could absorb 10% of the netnet annualannual increment ofof CO,.CO,.

• Continuing the present raterate ofof forestforest plantingplanting forfor the next 40' years willwill offset less thanthan 10%10% of the currentcurrent netnet CO2 CO, increase.increase.

• Afforestation ofof 22 toto 5 5 million million haha perper yearyear couldcould offset thethe CO,CO, emissionsemissions from tropical forests by the year 2020.2020.

The currentcurrent raterate ofof forest planting in thethe tropicstropics isis aboutabout 1.8 million ha per year (FAO 1993).

55,55. TO WHATWHATEXTENTARESUlTABLELANDSAVAILABLE EXTENT ARE SUITABLE LANDS AVAILABLE FOR AFFORESTAAFFORESTATION TlON AND REFORESTATION?REFORESTA TION? WHERE ARE THEY?THEY?

In orderorder toto answeranswer thisthis question,question, the the word word "suitable""suitable" mustmust firstfirst be qualified. It refers not just to a technical definition in terms of soils and climatic conditions.conditions. It also depends on social and economic factors. It is possible, at a price, toto establish trees almost anywhere;anywhere; the the cost,cost, however,however, willwill be not onlyonly inin money but in humanhuman terms, since muchmuch ofof the land that isis classified as "degraded" and available forfor plantations is in fact used by landless people. The decision to commit landland areaarea to forest plantationsplantations mustmust bebe technicallytechnically sound,sound, economicallyeconomically feasible and socially acceptable.acceptable.

Several estimatesestimates ofof land availableavailable forfor afforestation in thethe tropics have been made.made. Grainger (1990)(1990) estimates that therethere Climate Change, Forests and Forest ManagementManagement 103 may be 621621 millionmillion haha ofof landland "technically""technically" available.available. This estimate does not take intointo account socio-economicsocio-econonnic considerations. Of this, 41841 8 millionmillion haha areare inin dry,dry, montanemontane regions and 203 millionmillion haha areare forestforest fallowfallow inin humid humid areas.areas. According to HoughtonHoughton (1990)'(1990), up to 865865 millionmillion haha ofof landland are available inin the tropics forfor afforestation.afforestation. Of this total,total, there may be about 500500 millionmillion haha ofof abandonedabandoned lands that previously supported forests in Latin America (100 million ha),ha), Asia (100(100 millionmillion ha)ha) andand AfricaAfrica (300(300 millionmillion ha).ha). The additional area wouldwould bebe available onlyonly if increases in agricultural productivityproductivity on on otherother lands lands allowedallowed thesethese marginalmarginal landslands toto be removed fromfrom production.production. WinjumWinjum et alal (1992)(1992) estimate that aa combination of afforestation, agroforestryagroforestry andand forest protectionprotection onon 300-600300-600 million million ha ha ofof available available landland couldcould conserve and sequester 36-71 PgPg CCover over 5050 years.years.

InIn the nnidmid andand northernnorthern latitudes,latitudes, land uses have stabilized in most areas over the pastpast century,century, howeverhowever therethere areare stillstill ample opportunities for re/afforestationre/afforestation projects.projects. In somesome temperate zone countries, areaarea ofof forest landland hashas actuallyactually increasedincreased asas marginal agricultural landslands which havehave beenbeen abandoned havehave revertedreverted toto natural forests oror havehave beenbeen reforested. FranceFrance was 14% forested in 1789 and today 27% of its landland areaarea is forested. Within the pastpast 1515 yearsyears approximately 600600 000 haha per yearyear have come out ofof agricultural productionproduction inin Europe,Europe, of of whichwhich aboutabout 40%40% was transferredtransferred toto forest andand other woodedwooded landland (FAO(FAO 1992).

In the United States, there are anan estimatedestimated 46.846.8 million ha of crop and pasture lands which areare capable of growing treestrees andand are better suited to this purpose.purpose. ThereThere areare alsoalso opportunitiesopportunities for plantingplanting ofof fastfast growinggrowing treestrees forfor woodwood energyenergy productionproduction on 14-28 millionmillion haha and establishment of windbreakwindbreak plantingsplantings on 1.371.37 millionmillion ha.ha. If planted,planted, thesethese areasareas could provideprovide anan additional carboncarbon storagestorage capacity capacity of of from 66-210 millionmillion tonnes/yr (Sampson(Sampson andand HamiltonHamilton 1992). 104104 Climate Change,Change. Forests and Forest Management

One typetype of degradeddegraded landland thatthat maymay havehave potentialpotential forfor the establishment ofof plantations is salt-affected land,land, provided itit is notnot usedused byby peoplepeople whowho havehave nono otherother sourcesource ofof land.land. Reliable andand recentrecent estimatesestimates of such landland areare notnot availableavailable butbut in the tropicstropics therethere may be over 50 million ha both in AfricaAfrica and in Asia and over 30 million ha -in Latin America as well as large areas inin Australia and temperate and sub-tropical Asia (Massoud 1977). There are several active research programmes into into thethe selection of salt-tolerantsalt-tolerant speciesspecies andand provenances ofof plantationplantation trees, particularly in Australia and Asia, but itit shouldshould bebe noted noted thatthat therethere areare alsoalso researchresearch programmes intointo thethe developmentdevelopment ofof salt-tolerantsalt-tolerant agricultural crops. Nevertheless salt-affectedsalt-affected soilssoils areare anan importantimportant if ununquantified quantified source of land for plantations.plantations.

Based onon thethe aboveabove information,information, it would appear that there are large areasareas ofof suitablesuitable landland forfor afforestationafforestation and reforestationreforestation (in termsterms of being without encumbranceencumbrance and with reasonablyreasonably fast growthgrowth rates)rates) inin temperate North America,America, Europe,Europe, Australia, Chile, Argentina, BrazilBrazil andand Uruguay.Uruguay. In Africa there are large areasareas ofof degraded savannasavanna woodland, woodland, butbut thisthis has lower yieldyield potentialpotential andand maymay notnot be be unencumbered.unencumbered. It isis important toto keepkeep inin mind,mind, however,however, thatthat largelarge areasareas ofof plantation may not bebe thethe bestbest useuse ofof suchsuch land,land, especiallyespecially from the standpoint ofof thethe needsneeds of the people whowho presently occupy oror useuse it. it. Any large scalescale afforestationafforestation or reforestationreforestation projects shouldshould bebe partpart of a land useuse plan,plan, mademade withwith the full involvementinvolvement of thethe peoplepeople whowho dependdepend uponupon thethe land.land.

There is also considerableconsiderable potential for treetree planting in homestead gardens,gardens, windbreaks and agroforestryagroforestry systemssystems (See questionquestion 58).58)_ Climate Change, Forests and ForestForest ManagementManagement 105

56.56, WHAWHAT T OTHER CONSTRAINTS ARE THERE TO LARGE SCALE AFFORESTATIONAFFORESTA TION INITIATIVES?INITIA TIVES?

There are several otherother constraintsconstraints to large scale afforestationafforestation initiatives inin additionaddition toto thethe availabilityavailability ofof land.land. TheseThese cancan bebe classified into fourfour generalgeneral categories;categories; infrastructure, social,social, economic and ecological constraints.

INFRASTRUCTUREINFRA STRUCTURE CONSTRAINTSCONSTRAINTS -. Limited institutional capacity, lacklack ofof researchresearch onon appropriateappropriate speciesspecies to plant,plant, unrealistic government incentives,incentives, andand soaring'soaring populationspopulations rates resultingresulting inin increasedincreased pressurepressure onon availableavailable landland cancan constrain afforestation initiatives.initiatives.

SOCIAL CONSTRAINTS - -The The interestsinterests andand needs of locallocal people living in areas proposedproposed for afforestationafforestation are ofof paramount importance. WhenWhen goalsgoals and objectivesobjectives ofof forestryforestry projects do not coincidecoincide with thosethose ofof thethe locallocal people,people, thethe results will bebe lessless thanthan hopedhoped for.for. Farmers can easilyeasily perceive government sponsored afforestationafforestation or reforestation efforts asas anan encroachmentencroachment onon customarycustomary landland useuse rightsrights andand as a challengechallenge toto theirtheir welfare.welfare. ReactionsReactions of thisthis naturenature havehave often ledled toto activeactive opposition opposition andand eveneven sabotagesabotage throughthrough setting of intentionalintentional firesfires (Trexler(Trexler et al 1992).1992).

ECONOMIC CONSTRAINTSCONSTRAINTS - Costs of afforestation programmes areare highlyhighly variablevariable,; dependingdepending onon thethe nature of thethe terrainterrain toto bebe planted,planted, labourlabour costs,costs, andand treetree speciesspecies toto bebe planted. AA roughrough globalglobal estimateestimate indicatesindicates that treetree plantingplanting costs can range fromfrom aa lowlow of SUS$US 200200 to aa highhigh of SUS$US 2 000 perper ha.ha. ProjectedProjected socio-economicsocio-economic benefitsbenefits derivedderived fromfrom plantations may not justify plantingplanting costs.costs. (Bernthal(Bernthal 1990).1990). Therefore it would be difficult,difficult, ifif notnot impossible,impossible, for countriescountries receiving loans from developmentdevelopment banks for afforestationafforestation projects to repayrepay thethe loans.loans.

ECOLOGICAL CONSTRAINTSCONSTRAINTS - -Ecological Ecological drawbacksdrawbacks toto large afforestation projectsprojects include thethe potentialpotential forfor introducingintroducing lowlow 106 Climate Change, Forests and Forest Management levels of genetic variability whichwhich cancan characterizecharacterize largelarge areas of single species plantations. ThisThis cancan reducereduce their resistance to site oror climateclimate relatedrelated stressstress and (or) attack by insectsinsects andand disease. LargeLarge scale forest plantings can also strainstrain existing water resourcesresources inin areasareas whichwhich areare alreadyalready experiencingexperiencing overdrafts andand escalating demands on groundground waterwater resources.resources.

57. WHAWHAT T ASSISTANCE ISIS AVAILABLEAVAILABLE TOTO SUPPORT AFFORESTAAFFORESTATION TlON ANDAND REFORESTAREFORESTA TION, TlON, PARTICULARL YYA A T THE INTERNATIONALINTERNA TIONAL LEVEL?

Potential sources of funds include:include:

• National governments.

• International and regional development banks.

• Forest industryindustry..

• International donor agencies,agencies, e.g.e.g. UNDP.UNDP.

• Bilateral donors.donors.

• NGOs.NG0s.

• Private enterprise.enterprise.

• Public utilityutility companies interested inin offsetting carbon emissionsemissions

A large number ofof donors fromfrom the developed world,world, including international agencies, havehave extended financialfinancial support toto establishment of forest plantations inin the developing countries.countries. The World Bank hashas financedfinanced forestryforestry projects worth aboutabout $USSUS 2.52.5 billionbillion upup to to 1990.1990. MoreMore thanthan 50%50% ofof thisthis amountamount has beenbeen usedused for for plantation plantation forestryforestry (Pandey(Pandey 1992). 1992). In 1990, development aid forfor thethe fieldfield ofof actionaction "management"management ofof forestsforests Climate Change,Change, ForestsForests and ForestForest ManagementManagement 107 and plantations for industrial use" waswas SUS$US 347.6 millionmillion oror 25% ofof thethe total.total. This represents anan increase ofof 1.8 timestimes from thethe SUS$US 191.9191 .9 millionmillion mademade availableavailable inin 19881988 (Ball(Ball 1992)1992).. It is worth noting,noting, however,however, thatthat the the World World BankBank andand many bilateral donors are making fewer concessionaryconcessionary loansloans or grants for industrial roundroundwood wood plantations, onon thethe groundsgrounds that theythey shouldshould bebe profitableprofitable enoughenough to seekseek supportsupport fromfrom normal funding sources.sources.

The Global EnvironmentalEnvironmental Facility (GEF),(GEFl. which is implemented by thethe World.World · Bank,Bank, UNDPUNDP and UNEP,UNEP, is aa fundingfunding sourcesource which addresses four key environmentalenvironmental issues. These include reduction ofof GHGGHG emissions,emissions, protection of biodiversity, protection of internationalinternational waterswaters and and reductionreduction inin ozoneozone layerlayer depletion.

Another important component of afforestation and reforestation projects isis technicaltechnical assistance.assistance. This is alsoalso available throughthrough aa numbernumber ofof sourcessources includingincluding nationalnational governments, international technicaltechnical assistanceassistance agenciesagencies such as FAOFAO and and international international donorsdonors.. An innovative programme to assist rural communities in developingdeveloping countriescountries toto developdevelop more effective strategies, methods andand tools forfor forestryforestry activities, includingincluding tree planting,planting, isis thethe Forests,Forests, TreesTrees andand People ProgramProgram (FTPP).(FTPP). FTPP operatesoperates on on thethe basis of aa partnership betweenbetween aa community forestry team inin FAO'sFAO's Forestry Department inin RomeRome and several national and regional institutionsinstitutions inin Africa, AsiaAsia andand LatinLatin America.America.

58. HOW CANCAN AGROFORESTRYAGROFORESTRY ANDAND URBANURBAN TREETREE PLANTINGS CONTRIBUTE TOTO THE MITIGAMITIGATION TION OFOF CL/MACLIMA TE CHANGE?

The magnitude of carbon storage contribution from agroforestry plantingsplantings willwill depend onon thethe scalescale at at whichwhich itit is done andand thethe ultimateultimate use thatthat is made of the wood.wood. 1081 08 Climate Change, Forests and Forest Management

Given suitablesuitable economic,economic, social and environmentalenvironmental conditions,conditions, farmers have been found toto adoptadopt agroforestryagroforestry systemssystems readily. In countries where public forest landslands are limitedlimited in extent oror governmentgovernment treetree planting efforts are limited,limited, agroforestry plantings can represent- aa significantsignificant contributioncontribution to treetree plantingplanting andand carbon sequestration. ThereThere isis a potential for increasedincreased forestryforestry planting both inin tropicaltropical andand temperatetemperate zoneszones.. LargeLarge scale agroforestry tree planting schemesschemes such as the "Four"Four Around"Around" schemesschemes inin ChinaChina werewere reportedlyreportedly carriedcarried out over 6.5 millionmillion haha ofof agriculturalagricultural landslands duringduring the decadedecade 1981-1990. AA project project of of this this magnitude, magnitude, ifif successful,successful, wouldwould sequester largelarge amountsamounts ofof carbon asas wellwell as providing other environmental benefitsbenefits suchsuch asas protectionprotection ofof soilsoil fromfrom wind and water erosion.erosion.

Agroforestry systemssystems areare beingbeing consideredconsidered inin westernwestern EuropeEurope as anan alternativealternative intensiveintensive productionproduction systemssystems whichwhich areare currently inin placeplace that produceproduce largelarge surpluses of certain crops. In thethe UnitesUnites States.States, there are largelarge areasareas which which wouldwould benefit from increasedincreased windbreakwindbreak andand shelterbeltshelterbelt plantings (see(see question 55) (Sampson(Sampson and Hamilton 1992).

Urban treetree plantings would provideprovide a moremore limitedlimited carboncarbon storage benefit than ruralrural plantingsplantings becausebecause by their nature,nature, they wouldwould notnot bebe veryvery extensive.extensive. However they havehave the potentpotentialial to contributecontribute otherother benefitsbenefits inin thethe climateclimate changechange context which are much moremore significantsignificant (Fig(Fig 8.6). 8.6). TheThe effecteffect of urban treestrees on locallocal microclimates has undergoneundergone investigationinvestigation duringduring thethe pastpast twotwo decades,decades, largelylargely inin developed countries. It isis clearclear thatthat urbanurban treestrees havehave aa significantsignificant andand quantifiable effecteffect onon thethe immediateimmediate locallocal climate andand therethere have been variousvarious attempts attempts to to estimateestimate whatwhat thethe effect of aa major urban andand communitycommunity tree planting programme might be in the mitigation ofof carboncarbon emissions.emissions. OneOne estimateestimate fromfrom thethe USA equates thethe planting of 100100 millionmillion treestrees around around homes,homes, coupled with anan effort toto reducereduce heatheat absorption andand radiation ClimateC//mate Change, ForestsForests and Forest Management 109

Figure 8.68.6 - ShadeShade trees, suchsuch asas thesethese neemsneems planted along the streets of Niamey,Niamey, thethe capitalcapital ofof Niger, Niger, lowerlower temperatures temperatures andand provide aa moremore pleasantpleasant environment.environment. through aa programprogram of converting darkdark colouredcoloured surfaces,surfaces, suchsuch as parking lots and buildings toto light colourscolours with aa reductionreduction of about 1717 millionmillion tons of carboncarbon fromfrom enteringentering thethe atmosphere eacheach yearyear (Akbari(Akbari et alal 1988).1988). Chinese urbanurban foresters report that thethe climateclimate ofof somesome citiescities havehave beenbeen markedly altered through widespread tree planting programmes (see boxbox 8.1).

Trees can alsoalso havehave aa signsignificantificant beneficialbeneficial effecteffect on the costcost of winter heatingheating andand summersummer cooling ofof buildings.buildings. DependingDepending on itsits location,location, thethe energyenergy conservationconservation efforts ofof aa singlesingle urban tree cancan preventprevent thethe releaserelease of 115 5 timestimes moremore atmospheric carbon thanthan itit iiss able toto sequester.sequester. TreesTrees breakbreak up urbanurban "heat"heat islands"islands" byby providingproviding shade.shade. The shadeshade provided by strategicallystrategically placedplaced treestrees perper househouse cancan reducereduce home air conditioningconditioning needsneeds by by 3030 toto 50%.50%. TreesTrees plantedplanted asas 1101 1 O Climate Change, ForestsForests andand ForestForest Management windbreaks aroundaround buildingsbuildings inin temperatetemperate andand borealboreal regions can reduce winterwinter heating energy useuse byby 44 to to 22%,22%. ThereforeTherefore urban trees offer a dualdual benefit ofof storingstoring smallsmall amountsamounts ofof carbon and protecting buildingsbuildings from extremeextreme hot andand coldcold temperatures whichwhich resultsresults inin lower consumptionconsumption of fossilfossil fuels. Urban tree planting maymay bebe especiallyespecially beneficialbeneficial inin tropical regionsregions where trees grow rapidly and thethe directdirect cooling benefits of shadingshading are significant (Sampson(Sampson etet al 1992).

The effecteffect ofof planting planting treestrees aroundaround buildingsbuildings forfor energyenergy conservation isis sensitivesensitive toto thethe typetype and shape ofof the tree involved, as well as itsits locationlocation.. DeciduousDeciduous treestrees thatthat shadeshade west-facing windowswindows inin thethe summersummer butbut allowallow solarsolar radiation to strikestrike thethe samesame windowswindows inin winterwinter are are especiallyespecially desirable.desirable. In thethe northern hemisphere, trees on the south side ofof aa house should be talltall and fairlyfairly close toto the house, withwith the lower boles pruned soso thatthat thethe winterwinter sun can penetrate. ForFor trees to be energy efficient,efficient, it isis important thatthat species,species, locationlocation andand tree management bebe carefullycarefully andand properlyproperly matchedmatched toto the individual situation (Sampson(Sampson etet al 1992).1992). Climate Change, Forests and Forest Management 111

Box 8.18.1 Effects of treetree planting on micro-micro climate in Nanjing,Nanjing. ChinaChina

The industrialindustrial city of Nanjing.Nanjing,. with aa population ofof 1.51.5 million,million. isis knownknown asas oneone of the fivefive "furnace"furnace cities"cities" ofof the the Yangtze Yangtze valley.valley. SinceSince 1949,1949. somesome 3.43.4 millionmillion treestrees have been plantedplanted inin and around thethe city with thethe specificspecific objective of reducingreducing summer temperatures and generally regulating thethe local climate.climate, purifying thethe airair and beautifyingbeautifying thethe environment.environment. It is claimed thatthat aa dropdrop inin averageaverage summersummer temperature fromfrom 32.2° CC toto 29.4°C29.4°C overover the . period 1949 to 1981 isis directly attributable toto the coolingcooling effect ofof treetree planting. OverOver 3232 years,years. somesome 2323 treestrees perper inha~itantinhabitant werewere planted.planted. Tree plantingsplantings includeinclude block afforestationafforestation of degradeddegraded hillsides.hillsides, windbreaks.windbreaks, tripletriple rowsrows of treestrees along rarailwaysilways and planting of streetstreet treestrees (Carter 1994). 1121 1 2 Climate Change, Forests and Forest Management

59. IS THETHE PLANTINGPLANTING OFOF TREESTREES SOLELYSOLEL Y FOR CO2CO2 ABSORPTlONAABSORPTIONA SOUNDSOUND POLICYCONSIDERINGPOLICY CONSIDERING OTHEROTHER NEEDS FORFOR AVAILABLEA VAILABLE LAND?

There are many uncertainties presently associated withwith the global climate changechange issue.issue. In addition, in many countries, the amount ofof landland available thatthat is suitable forfor agriculture and . (or) forestryforestry is limited. Therefore,Therefore, any forest sectorsector responsesresponses to adapt to oror mitigate the potential effects of climate change should represent sound policy independent of predicted global warming and produce netnet benefits separateseparate fromfrom thosethose whichwhich may ultimatelyultimately arisearise in thethe climateclimate changechange contextcontext (e.g.(e.g. timber, fuel wood, watershedwatershed protection, nonnon wood productsproducts and non commoditycommodity values such asas ecotourismecotourism andand recreation).recreation).

The position of FAOFAO withwith respectrespect toto afforestationafforestation forfor CO2CO2 absorption is to encourage treetree plantingplanting inin areasareas wherewhere forestforest cover is the appropriate vegetation.vegetation. ThisThis shouldshould be defined by land use plans andand forestforest strategies as described inin documents prepared underunder thethe Tropical Forests Action PlanPlan (TFAP)(TFAP) and not byby theoreticaltheoretical targetstargets (FAO(FAO 1990)1990) (see(see alsoalso questionquestion 45).

Instead ofof focusingfocusing narrowly on afforestation or reforestation, FAO supports the adoption of anan integratedintegrated approachapproach which includes:

• Management andand protectionprotection of existing areas ofof natural forest to provide for long-term sustainedsustained yield productivity of a wide range ofof commoditycommodity

and non-commoditynon-commodity resourcesresources includingincluding CO2CO 2 absorption.

• Gradually increasingincreasing effortsefforts inin thethe afforestation or reforestation of appropriate sitessites withwith followfollow- up management and protection.

• Appropriate utilization of thethe woodwood producedproduced to reduce the rate ofof carboncarbon release.release . Climate Change, Forests and Forest ManagementManagement 113

60. WHAWHAT T FORESTFOREST POLICIES SHOULDSHOULD BEBE CONSIDEREDCONSIDERED AAT T THETHE COUNTRYCOUNTRY LEVEL TO ADDRESS THE THREATHREAT T OF CLlMACLIMA TE CHANGE?CHANGE?

A policy aimed at reduction of current levelslevels of deforestation and forest degradationdegradation shouldshould bebe ofof highhigh prioritypriority inin thosethose countries wherewhere deforestationdeforestation is a majormajor activity.activity. The implementation ofof suchsuch a policy will requirerequire actions inin both thethe forestry and agricultural sectorsector (see(see question question 46). 46). AA policypolicy ofof afforestation/reforestation isis alsoalso warranted provided thatthat it is economically.economically, ecologicallyecologically andand sociallysocially sound.sound, eveneven in thethe absence of climateclimate changechange considerations.considerations. Afforestation/Afforestation/ reforestation initiativesinitiatives should should bebe accompaniedaccompanied byby policiespolicies and programmes designed toto ensure thethe health of both plantations and natural forestsforests so thatthat the objectives of investments made in forest sector development willwill be met.met. AA policypolicy ofof partialpartial replacement of of fossil energy sources byby wood andand otherother biofuels is alsoalso worthyworthy of consideration. UseUse ofof woodwood inin placeplace of materialsmaterials fromfrom otherother sourcessources whosewhose productionproduction requiresrequires many times moremore energyenergy contributescontributes toto energyenergy savings,savings. reduction of GHGGHG emissionsemissions and to thethe maintenancemaintenance ofof existing carboncarbon reservoirs.reservoirs.

In developing forestforest sectorsector policiespolicies toto mitigatemitigate thethe effectseffects ofof predicted global climate change.change, it must bebe recognizedrecognized that these can only bebe done in concertconcert withwith parallelparallel measuresmeasures toto reduce fossilfossil fuel emissionsemissions and toto promotepromote sustainablesustainable agriculture. Most of the present dayday contributioncontribution of greenhouse gasesgases is is the the resultresult ofof the burning of fossilfossil fuels.fuels. Conservation of fossil fuels and the useuse of alternative energyenergy sources.sources, including thethe use ofof renewablerenewable energyenergy sourcessources isis therefore,therefore. essential.essential. 1141 1 4 Climate Change, Forests and ForestForest ManagementManagement

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INDEX

A carbon fixing-99 acid rain-26 carbon monoxide-18,21monoxide-18,21 adaptation-74,adaptation-74,81 81-83-83 carbon/nitrogen ratio-70 aerosols-25,26 carbon pool-41,84pool-41 ,84 afforestation-77,84,100,102-afforestation-77 ,84,100,102- carbon reservoirreservoir-49,92,113-49,92,113 107,111-113 carboncarbon sequestration-57sequestration-57,98,108 ,98,108 Agenda 21-84 carbon sink-40,43,44,49,80,96sink-40,43,44,49,80,96 agriculture-1,18,22,27,47,53,agriculture-l, 18,22,27,47,53, carbon source-40,43,44source-40,43,44,49,,49, 54,56,68,80,86,112,54,56,68,80,86,1 12, 80,96 113 carbon uptake-52,53uptake-52,53 agroforestry-103,104,107,108agroforestry-1 03, 104, 107,108 carbonic acid-13acid-13 air pollution-68,83 cash crops-87crops-a7 albedo-9,53 CFC-18,21,24,25 alpine plants-60 CH4-18,19,24,37,46,53CH,-18,19,24,37,46,53 altitude-58,60 charcoal-22,54,90 anomalies-39,68,79 climateclimate prediction models-63models-63 anthropogenic-68 climate prediction-63 aquaculture-64 climate zones-58zones-58 asteroid-9,10asteroid-9, 1° climaticclimatic anomalies-39,68,79 atmospheric concentration-25concentration-25 climatic variability-32,74 atmospheric levels-27,28,59 climax species-79species-79 cloud formation-63 B clouds-9,15,25,26,27,31,clouds-9,1 5,25,26,27,31, bacteria-46 36,60,63 bark beetle-70 CO2-(seeCO,-(see carboncarbon dioxide) biofuels-90biofuels-90,91,92,113,91 ,92, 113 CO, fertilization effect-34effect-34,35,43,35.43 biomassburningbiomassburning-19,52,53,54,87-19,52,53,54,87 CO, storage-98storage-98 biomass-19,21,40,41,49,50,52, coal-54 53,54,66,67,87,88, coastal zones-64zones-64 90,92,93 combustibleco mbustible fuefuels-67,70,88,90ls-67, 70,88,90 boreal forest-60,71 combustion-19,21,90combustion-19,21,90 brush fire-55tire-55 competition-75,76 burning-burning-1,18,19,21,22,47,53,1,18,19,21,22,47,53, conservation-84,85,96,98,109, 54,56,87,8854,56,87,88,90,113,90,113 110,113 constraints-56constraints-56 C continental glaciers-5glaciers-5 carbon absorption-47,49,52,53, cooking stoves-92 98,102 cooling-7,cooling-7,10,11,13,26,60, 10, 11,13,26,60, carbon balance-52 109,110,114 carbon cyccycle-2,40,42,44,53,82le-2,40,42,44,53,82 carbon dioxide-l,dioxide-1,13,15,17,18, 13,15,17,18, D 19,22,24,28,8219,22,24,28,82 deciduous trees-trees-1101 10 carbon exchange-43,48exchange-43,48 deep freeze events-68 1124 24 Climate Change, Forests andand ForestForest ManagementManagement defoliation-70 fire management-77,88,89management-77,88,89 defoliator-68,defoliator-68,69,70 69,70 fire season-66season-S6 deforestation-18,19,22,43,47, fisheries-1,27,64 53,55,56,86,92,113 fixation rate-99rate-99 degraded forests-47 flammable fuels-70 desert-5,25,35,50 flux-40,41,43,83 desertification-92 development-1,10,18,27,56,77,development-1,1 0,18,27,56,77, forest decline-68,78decline-68,78 82,83,84,85,86,87,94, forest ecosystem-47,49,59,82, 96,98,104,105,106,113 83 development plans-77plans-77 forest fuels-89fuels-89 donors-106,107donors-l 06,1 07 forest health-67,68,76,77health-67,68,76,77 drought-8,12,38,39,66,67,68 forest industry-106industry-106 74 forest management-2,75,76,80,management-2,75,76,80, 83,94 E forest plantation-52,53,71,91, ecologically sustainable-81sustainable-81 99,100,102,106 ecologists-65,66 forest planting-52,53,71,91planting-52,53,71,91 economic-30,77,81,84,86,98economic-30, 77 ,81,84,86,98 99,100,102,106 105,108 forest policies-113policies-l1 3 economic benefits-105benefits-l05 forest products-54,64,78,96,97 economic constraints-105constraints-l05 98 economic factors-102factors-l02 forest sector-53,68,sector-53,68,77,80,83,85 77 ,80,83, 85 economic incentives-97incentives-97 86,112,113 economically feasible-102feasible-l02 forest soil-46,49,56,82,87 ecosystem-21,47,49,57,59,ecosystem-21,47 ,49,57 ,59, forestry-1,2,21,27,80,82,83forestry-1,2,21,27,80,82,83 60,82,83,88 93,103,104,105,10693,1 03,104,105,106 El Nino-9,ll,12,66Niño-9,1 1,12,66 107,108,112 elevation-13,47elevation-13,47,60,62,65,73,75 ,60,62,65, 73, 75 Forests Trees andand PeoplePeople emissions-ll,22,23,25,30,43,47emissions-11,22,23,25,30,43,47 Programme-l07Programme-107 52,56,86,87,88,90,91, fossil energy-113energy-ll 3 92,93,102,106,107, fossil fuel emissions-43,52,113 108,113 fossilfuels-1,18,19,21,22,25,40fossil fuels-1, 18,19,21,22,25,40 ENSO-12,20,66 47,92,93,110,113 epidemic-67 fossil pollen-4,58 eerosion-9,56,64,94,108rosion-9,56,64,94, 108 Framework Convention onon evapo-tevapo-transpiration-9,53ran spi ration-9,53 Climate Change-84Change-84 evaporation-32,evaporation-32,33,63 33, 63 fuel breaks-88breaks-88 evolution-66,evolution-66,75,102 75,102 fuels-66,67,70,88,89,90 extinction-64,65,66 fuelwood-90 fungi-46 F FAOFAO-45,84,85,88,94,107,112-45,84,85,88,94,107,112 fire-47fire-47,54,55,66,70,76,77 ,54,55,66, 70, 76, 77 87,88,89,90 Climate Change, Forests and Forest ManagementManagement 125

G integratedintegrated firefire management-88management-88 gene pool-78 integratedintegrated pestpest general circulation modelmodel (GCM)-(GCM)- management(IPM)-77management(lPM)-77 27-33,36,38,66,67 interglacialinterglacial era-58era-58 genetic base-71base-71,76,77 ,76,77 interglacialinterglacial period-16period-16 genetic variabilityvariability-75,82,106-75,82,1 06 international agencies-84,106agencies-S4, 106 genetic variation-66variation-66 international agreements-83,84agreements-83,S4 geologic history-4,6,31 inventories-76,82 glaciers-4,5,7 global warming potentialpotential (GWP)-(GWP)- L 22,24 land use plan-1plan-104,112 04, 112 global warming-1,warming-1,18,60,92,112 18,60,92, 112 lightning-21lightning-21,54,67 ,54,67 Global EnvironmentalEnvironmental Facility-1Facility-107 07 lightninglightning frequency-67frequency-67 grasslands-21grasslands-21,53 ,53 lightninglightning storms-54storms-54 grazing-22grazing-22,53,53 . Little IceIce Age-7,10,11Age-7, 10, 11 greenhouse effect-2,eff ect-2,15,16,18, 15, 16, 18, livestock-53,54,87livestock-53,54,87 23,25,33,38 livestocklivestock management-21,87management-21 ,87 greenhouse gas (GHG)-15,(GHG)-15,16,18, 16, 18, lumber-64lumber-64 21-28,30 growthgrowth-34,38,41,45-47,53,59,-34,38,41 ,45-47,53,59, M 74,80,86,9074,80,86,90-93,107-93, 107 mangrove-64 markets-64 H MedievalMedievaIOptimum-7,S Optimum-7,8 habitat-64,75,96 Mesozoic Era-4Era-4 harvest scheduling-76 methane-18,19,24,37,46,53methane-1S, 19,24,37 ,46,53 harvesting-93-96,98 microbial activity-37,57 hazard-67,hazard-67,71,76,78 71,76,78 microclimate-108microclimate- 10B healthhealth-21,67,68,71,73,76,-21 ,67,68,71,73,76, migration-58,64 7777,83,113 ,83, 113 Milankovitch Theory-10Theory-10 heat ¡stands-109islands-1 09 missing carbon sink-43 Holdridge Life Zone-50,61Zone-50,61 mitigation-74mitigation-74,80,81,107,108,80,81,1 07, 108 homestead gardens-104 models-28,30,53,63,66,83 hurricane-12,32,38,67 monitoring-23,monitoring-23,77,78 77,78 hydrogen-10 N natural forest-49,96,forest-49,96,103,112 103, 112 ice age-1,5,7,10,11,16,23 113 5858 natural range-58,59,60,64range-58,59,60,64,65,65 iceice core-15,core-15,17,23,24 17 ,23,24 75,78 increment-1increment-100,102 00, 102 nitrogen-18,37,70 IndustIndustrialrial Revolution-18,31 nitrogen fertifertilizers-19,43lizers-19,43 infrastructure-105infrastructure-105 nitrogen fixation-37 insects-46,57insects-46,57,68-71,76,77 ,68-71,76,77 nitrogen oxides(NO,)-18,21oxides(NO)-18,21,37 ,37 79,90,106 nitrous oxide(N,O)-18oxide(N20)-18,19,24, 19,24 non-wood products-98,101products-98,1 01 1, 2626 Climate Change,Change, ForestsForests andand ForestForest ManagementManagement northern hemisphere-7,9,20,33hemisphere-7,9,20,33 prescription-54,76 43,58,75,110 presuppression-77presuppression-77,88 ,88 nutrient-37nutrient-37,57,76 ,57 ,76 prevention-77prevention-77,88 ,88 provenance-76,77,provenance-76,77,100,104 100, 104 o0 . public utility companies-106companies-106 ocean-5,9,11-13,20,27,30,31ocean-5,9, 11-13,20,27,30,31 32,34,40,41,43,93 R ocean circulation-9,34 radiation-10,radiation-10,11,14,15,21,108 11, 14, 15,21,108 ocean currents-11,12currents-' 1,12 rain forests-12,63,66,67forests-12,63,66,67 offset-47,57,100,102,106ollset-47 ,57,100,1 02,106 rainfall-5,12,32,53,58,63,rainfall-5,12,32,53,58,63, organic matter-4,37,46,83,94matter-4,37,46,83,94 67,68 ozone-18,21 recycling-98 ozone hole-21 refreforestation orestation-77,100,102,104--77,1 00, 1 02, 1 04- 107,112,113 pP regional climate change-73change-73 Palaeozoic EraEra research-28,35,52,63,78,research-28 ,35, 52,63, 7 8, paper products-54,98 81-83,86,104,10581 -83,86,104,105 peat-44 residenceresidence times-22 peat bogs-44 roots-46roots-46 peat deposit-54 rotation-99rotation-99 peatlands-44,82 rotationrotation age-98age-98 pest management-77 rotation length-76,99length-76,99 pests-36,64,67pests-36,64,67,68,71,72,76-78 ,68, 71,72,76-78 96 S photosynthesis-27photosynthesis-27,34,35,45,57 ,34,35,45, 5 7 sisilviculture-77lviculture-77 phytoplankton-9,12 sinks-2,12,30,40,42,43,45,49 Pinatubo-11,20 74,80,82,96,99 plant community-45community-45,57,58,64,57,58,64 soil-4,soil-4,19,21,27,32,36,37,40,41 19,21 ,27,32,36,37,40,41 plant health-71 46,47,49,51,56,57,67 plantations-45,52,53,plantations-45,52,53,71,91-93 71 ,9 1-93 73,76,82,83,87,93,9473,76,82,83,87,93,94 9797,99-102,104-107,113,99-102,104-107,113 98,99,102,104,108 plantation pests-71pests-71 soil nutrients,37,76nutrients,37, 76 plantingls)-52,planting(s)-52,78,96,100- 78,96,100- solar radiation-10,radiation-10,11,15,31,110 11,15,31 ,110 112 sources-2,18,sources-2, 18, 19,2119,21,22,25,26,30 ,22,25,26,30 planting programme-77programme-77 37,40,42,43,45,68,74 planting stock-76,77 80,82,85,86,88,90,92 Pleistocene Period-7,58Period-7,58,64,64 93,96,98,100,106,107 policiespolicies-74,80,85,94,113-74,80,85,94,113 113 policy-3,85,policy-3,85,112,113 112, 113 southern hemisphere-7,9 pollen-4,58,59 stems-45,46,94 pollen sterility-36,59 stress-66,67stress-66,67,68,70,73,75,76 ,68, 70, 73, 75, 76 precipitation-6,precipitation-6,7,12,27,29,31 7,12,27,29,31 84,106 32,34-36,38,47, sun-9,sun-9,10,11,14,15,26,110 10, 11,14,15,26,110 66,73,99 sunspots-10 prescribed fire-54,88fire-54,88 Climate Change, Forests and ForestForest ManagementManagement 127727

T U Tambora-llTambora-11 ultraviolet radiation-21radiation-21 temperateforesttemperateforest-46,50,53,64,71-46,50,53,64,71 UNCED-84 temperate ecosystem-60 UNDP-85,UNDP-85,106,107 106, 107 temperate region-56,110region-56, 110 UNEP-l07UNEP-107 temperate lone-4,55,99,1zone-4,55,99,100 00 urban foresters-109foresters-l09 103,108 urban plantings-107plantings-l07 temperature-ltemperature-1,5-7,9-17,22,27 ,5-7,9-17,22,27 urban trees-ltrees-108-110 08-11 0 28,3028,30-39,47,53,58,59,-39,4 7,53,58,59, utilization-92-94,112 61,62,64,68,71,10961,62,64,68,71,109-- 111 V terrestrialterrestrial sink-43sink-43 vegetation-4,9,45,51,54,55vegetation-4,9,45,51 ,54,55 timbertimber-96,112.-96,112, 56,58,66,79,90,95,11256,58,66,79,90,95,112 timber harvesting-93-96harvesting-93-96 vegetation communies-70communies-70 timber salvage-78salvage-78 vegetation type-61type-6 1 transpiration-9,transpiration-9,53,63 5 3,63 vegetation zone-62zone-62 tree crowns-45crowns-45 volcano-11,20,25volcano-ll,20,25 treetree improvement-76,78improvement-76,78 volume(s)-19,25,41,47,67volume(sl-19,25,41,47,67 treetree planting-71,104,105planting-71,104,105,107-,107- 7070,88,88 112 tree ranges-58ranges-58 W treetree rings-4rings-4 warming-1-7,9,10,12,18,22warming-1-7 ,9, 10 , 12, 18,22 tree species-37,57-59,64,77,82species-37,,57-59,64,77,82 24,26,32,33,58,6024,26,32,33,58,60 99,100,105 65,68,73,92,11265,68,73,92,112 tree(s)-8,46,57,65,94,109,110tree(sl-8,46,57 ,65,94,109,110 water-7,9,11,12,13,25,34water-7 ,9, 11,12,13,25,34 tropical deforestation-47,55deforestation-47, 55 35,39,40,56,57,63 56 95,107,108 tropical dry forest-49,50 water resources-98,106resources-gB,1 06 tropical ecosystem-60ecosystem-60 . water vapour-18vapour-18 tropical forests-19,46,53,67,68 watershed protection-112 71,86,93,99,10271 ,86,93,99,102 weather-4,5,9,11,12,21,32weather-4,5,9, 11,12,21 ,32 Tropical Forests Action 44,88 Programme (TFAPI-77,85,112(TFAP)-77,85,112 wildfire-36,47,54,66,67,70wildfire-36,4 7 ,54,66,67,70 tropical moist forest-49,50 76,78,88,90 tropical pines-68,69pines-68,69 windbreak-45,103,104,108,110windbreak-45,1 03, 104, 108, 11 0 tropical rain forest-35,44,63forest-35,44,63,66,66 111 67 WMO-4 tropical region-110region-ll 0 wood-22,54,64,84,90,92,94 tropicaltropicalstorms storms-31,32,33,64,67-3 1,32,33,64,67 96-99,101,107,112 tropical wet forest-50forest-50 113 tropical zone-99,108zone-99,1 08 woodwood energy-103energy-l03 tundra-44,50,58 wood processing-103processing-l03 typhoon-32 wood products-54,71products-54,71 wood waste-93 wooded area-45,46 1281 28 Climate Change,Change, ForestsForests andand ForestForest ManagementManagement wooded lands-54,103lands-54,1 03 wooden structures-88structures-8B woodlands-47,50,53,56,87,104woodlands-47 ,50,53,56,87,104 woodland fires-88 woodstoves-92 woody material-66material-66 woody plants-45plants-45 woody tissue-2,98 woody vegetation-45vegetation-45 World BankBank-85,106,107-85,1 06, 107

XYZ yarding-94 Year Without Summer-1Summer-' 1 1 FAO TECHNICAL PAPERSPAPERS

FAO FORESTRYFORESTRY PAPERSPAPERS

1 Forest utilization contracts onon publicpublic land,land, 19771977 (E (E FF S)5) 2 Planning forest roads and harvesting systems, 19771977 (E (E FF S)S) 3 World list of forestryforestry schools,schools, 19771977 (E/F/S) (E /F/S) 3 Rev.1Rev.1 World list of forestryforestry schools,schools, 19811981 (E/F/S)(E/F/S) 3 Rev.2 World list of forestryforestry schools,schools, 19861986 (E/F/S) (E /F/S) 4/14/ 1 World pulp and paper demanddemand,, supply supply and and trade trade 1- 1- Vol. 1," 1977 (E(E FF S)5) 4/24/2 World pulp and paper demand, supplysupply andand trade trade - - Vol. 2, 19771977 (E (E FF S)5) 5 The marketing of tropical wood inin SouthSouth America,America, 19761976 IE(E S)SI 6 National parks planningplanning,, 19761976 (E FF SU)S**) 7 Forestry for local community development,development, 19781978 (Ar (Ar E E F F S)5) 8 Establishment techniquestechniques for for forestforest plantationsplantations,, 1978 (Ar C E*E· FF S)SI 9 Wood chipschips - production,production, handling,handling, transport,transport, 19761976 (C (C E E S) S) 10/1 Assessment of logging costs from forest inventoriesinventories in the tropics - 11.. Principles and methodology, 19781978 (E(E FF S)S) 10/210/2 Assessment of logging costs from forest inventoriesinventories in the tropics - 2. DataData collectioncollection andand calculations,ca lculations, 19781978 (E (E FF S)5) 11 Savanna afforeafforestationstation in Africa,Africa, 19771977 (E (E F)F) 12 China: forestry support for agriculture,agriculture, 19781978 (E)(E) 13 Forest products prices 19601960-1977,-1977, 1979 1979 (E/F/S) (E /F/S) 14 Mountain forest roadsroads and harvesting,harvesting, 19791979 (E) (E) 14 Rev.1Rev .1 Logging and transport in steep terrain, 19851985 (E)(El 15 AGRAGRISIS forestryforestry - worldworld cataloguecatalogue ofof informationinformation andand documentationdocumentation servicesservices,, 19791979 (E/F/S) (E /F/S) 16 China: integrated wood processingprocessing industries, 19791979 (E(E FF SIS) 17 Economic analysis ofof forestry projects, 19791979 (E (E FF S)SI 17 Sup.1Sup.l Economic analysis ofof forestry projects: casecase studies,studies, 19791979 (E (E SISI 17 Sup.2 EconomicEconomic analysis analysis ofof forestryforestry projects: projects: readings,readings, 19801980 (C (C E)El 18 Forest products prices 19601960-1978,-1978, 1980 1980 (E/F/S) (E /F/S) 1919/1/ 1 Pulping and paper-makingpaper-making properties properties of of fast-growingfast-growing plantation wood species -- Vol. 1," 19801980 (E)(E)' 1919/2/2 Pulping and paper-makingpaper-making properties properties of of fast-growingfast-growing plantation wood species -- Vol. 2,2, 19801980 (E) (E) 20 Forest tree improvement, 19851985 (C (C EE F F SI5) 20/2 A guide to forest seedseed handling,handling, 19851985 (E (E S5 ) 21 Impact on soils ofof fast-growingfast-growing species inin lowlandlowland humidhumid tropics tropics,, 19801980 lE(E F S)SI 22/122/1 Forest volume estimation and yield predictionprediction - Vol. 1.1. VolumeVolume estimation, 19801980 (C (C EE FF S)SI 22/2 Forest vovolumelume estimation and yield predictionprediction - Vol. 2. YieldYield prediction, 19801980 (C (C EE FF SISI 23 Forest productsproducts pricesprices 19611961-1980,-1980, 19811981 (E/F/S)(ElF/SI 24 Cable logging systems, 19811981 (C(C E)E) 25 Public forestry administrations in LatinLatin America,America, 19811981 (E)(El 26 Forestry and rural development, 19811981 (ElE FF SIS) 27 Manual of forest inventory, 19811981 (ElE FI 28 Small and medium sawmills in developing countries, 1981 (E(E SISI 29 World forest products,products, demanddemand and supply 1990 and 2000.2000, 19821982 (E (E FF S)5) 30 Tropical forest resources,resources, 1982 (ElE FF S) 31 AppAppropriateropriate technology in forestry, 19821982 (E) (E) 32 ClassificationClassification and definitions of forest products,products. 19821982 (Ar/E/F/S)(Ar/E/F/S) 33 Logging of mountain forests,forests, 19821982 (E lE FF S) S) 34 Fruit-bearingFruit-bearing forest trees,trees. 19821982 (E (E FF SI 5) 35 Forestry in China, 1982 (C(e E)El 36 Basic technology in forest operations,operations. 19821982 (ElE FF S)SI 37 Conservation and development of tropical forest resources, 19821982 (E(E FF S)SI 38 Forest products prices 1962-1981.1962-1981, 19821982 (E/F/S)(E/F/S) 39 Frame saw manual, 1982 (E)(E) 40 CircularCircular saw manual, 19831983 (E)(E) 41 Simple technologies for charcoal making, 1983 (ElE F SISl 42 Fuelwood supplies in the developing countries, 1983 (Ar(Ar EE FF S)S) 43 Forest revenue systesystemsms in developing countries, 19831983 IE lE FF S) S) 44/144/1 Food and fruitfruit-bearing-bearing forest speciesspecies - 1. Examples fromfrom eastern Africa, 19831983 (E (E FF S)S) 4444/2/2 Food and fruitfruit-bearing-bearing forest speciesspecies - 2. Examples from southeasternsoutheastern Asia,Asia, 19841984 (E (E FF S)S) 44/3 Food and fruitfruit-bearing-bearing forest speciesspecies - 3. Examples fromfrom Latin America, 19861986 (E (E SIS) 45 Establishing pulp and paper mills, 19831983 (E)(E) 46 Forest products prices 1963-1982,1963-1982, 19831983 (E/F/S) (E/F/S) 47 Technical forestry education - designdesign andand implementation, 1984 (E(E F S)5) 48 Land evaluation for forestry, 19841984 IC (C E E F F SI 51 49 Wood extraction with oxenoxen andand agriculturalagricultural tractors,tractors. 19861986 (E (E F F SI 50 Changes inin shiftingshifting cultivation in Africa, 19841984 (E (E F)Fl . 50/1 Changes inin shiftingshifting cultcultivationivation in Africa -- sevenseven case-studies,case-studies, 19851985 (E) (E) 51/1 Studies on thethe volume andand yieyieldld ofof tropicaltropical forestforest standsstands -- 1.1. DryDry forestforest formations,formations, 19891989 (E (E F)F) 5252/1/ 1 Cost estiestimatingmating in sawmilling industries:industries: guidelines,guidelines, 19841984 (E) (E) 52/2 Field manualmanual onon costcost estimationestimation in sawmiltingsawmilling industries, 19851985 (El(E) 53 IntIntensiveensive mulmultiple-usetiple-use forestforest managementmanagement inin Kerala,Kerala, 19841984 (E (E FF SI5) 54 Planificaci6nPlanificación del desarrotfodesarrollo forestal, 1984 (S) (5) 55 IntensiveIntensive multiplmultiple-usee-use forestforest management inin thethe tropics,tropics, 1985 (E(E FF SI 56 Breeding poplarpoplarss for disease resistance, 1985 (E)(El 57 Coconut wood - ProcessingProcessing and use, 1985 (E(E SI 58 SawdoctoSawdoctoringring manual, 1985 (ElE SI 59 The ecoecologicallogical eHectseffects of eucalyptus,eucalyptus, 19851985 (C (C EE F F SISI 60 Monitoring and evaluation ofof participatory forestry projects, 19851985 (ElE FF S)S) 61 Forest productsproducts prpricesices 1965-1984,1965-1984. 19851985 (E/F/S) (E/F/S) 62 WoWorldrld list of institutionsin stitutions engagedengaged in forestry andand forest productsproducts research,research, 1985 (E/F/S)(E/F/S) 63 IIndustrialndustrial charcoal making,making, 19851985 (E) (E) 64 Tree growing by ruralrural people, 1985 (Ar(Ar EE FF S)SI 65 Forest legislationlegislation in selected AfAfricanri can countries.countries, 19861986 (E(E F)F) 66 Forestry extension organization, 19861986 (C (C EE S) S) 67 Some medicinal forestforest plants of Africa andand LatinLatin America,America. 19861986 (E) (E) 68 Appropriate forest industries,industries. 19861986 (E) (E) 69 Management ofof forest industries, 1986 lE)(E) 70 Wildland fire managementmanagement terminology, 19861986 (E/F/S) (E/F/S) 71 WorldWorld compendium of forestry andand forest productsproducts research institutions, 1986 (E/F/S)(E/F/S) 72 Wood gas as engine fuel, 1986 (E(E S)5) 73 Forest products:products: world outlook projections 1985-2000, 19861986 (E/F/S) (E /F/S) 74 Guidelines for forestry informationinformation processing,processing, 19861986 (E) (E) 75 Monitoring andand evaluation of social forestry inin IndiaIndia - anan operationaloperational guide,guide, 1986 (E)(E) 76 Wood preservation manual, 1986 (E)(E) 77 Databook onon endangeredendangered tree andand shrubshrub speciesspecies andand provenances,provenances, 1986 (E)(E) 78 Appropriate wood harvestingharvesting in plantation forests,forests, 19871987 (E) (E) 79 Small-scale fforest-basedorest-based processing enterprises, 1987 (E(E F S)5) 80 Forestry extension methods, 19871987 (E) (E) 81 Guidelines forfor forest policy formulation, 19871987 (C(e E)E) 82 ForestForest products prices 1967-19861967-1986,, 19881988 (E/F/S) (E/F/S) 83 Trade in forest products: a study of thethe barriersbarriers facedfaced by thethe developingdeveloping countries, 19881988 (E) (E) 84 Forest products: World outlook projections - ProductProduct andand countrycountry tablestables 19871987-2000,-2000, 19881988 (E/F/S) (E/F/S) 85 Forestry extension curricula, 19881988 (E/F/S)(E/F/S) 86 Forestry policiespoli cies inin Europe,Europe, 1988 (E) (E) 87 Small-scale harvesting operoperationsations ofof wood andand non-wood forestforest productsproducts involving ruralrural people,people, 19881988 (E (E FF S) S) 88 Management of tropical moist forests inin Africa,Africa, 19891989 (E (E FF P)P) 89 ReviewReview of forest managementmanagement systems of tropical Asia, 19891989 (E)(E) 90 Forestry and food security, 1989 (Ar(Ar EE SI5) 91 DesignDes ign manual onon basic woodwood harvesting technology,technology, 19891989 (E (E FF S)5) (Published only as FAO Training Series, No. 18) 92 Forestry policies in Europe -- An analysis, 1989 (E)(E) 93 Energy conservation in the mechanical forest industries, 19901990 (E (E SI5) 94 Manual on sawmill operationalope rational maintenance,maintenance, 1990 (E)(E) 95 Forest products prices 1969-1988, 19901990 (E/F/S) (E/F/S) 96 Planning and managing forestryforestry research: guidelines for managers,managers, 1990 (E)(E) 97 Non-wood forestforest products: the wayway ahead,ahead, 19911991 (E(E S)5) 98 Timber plantations in the humid tropics of Africa,Africa, 19931993 (E lE F)F) 99 Cost control in forest harvestingharvesting andand roadroad construction,construction, 19921992 (E) (E) 100 Introduction toto ergonomicsergonomics in forestryforestry inin developingdeveloping countries,countries, 19921992 (E(E FF I)I) 101 Management and conservationconservation ofof closedclosed forestsforests in tropicaltropical America, 1993 IE(E F PP 515) 102 Research managementmanagement inin forestry,forestry, 19921992 (E (E FF S) 5) 103 Mixed and pure forest plantations in the tropics andand subtropics, 19921992 (E) (E) 104 Forest products prices 19711971-1990,-1990, 19921992 (E/F/S) (E/F/S) 105 Compendium of pulp and paper training and research institutions, 19921992 (E) (E) 106 Economic assessment ofof forestry project impacts,impacts, 19921992 (E (E F)F) 107 Conservation of genetic resourcesresources inin tropicaltropical forestforest management -- Principles and concepts, 1993 (E)(E) 108 A decade of wood energyenergy activities within thethe NairobiNairobi ProgrammeProgramme of Action, 19931993 (E) IEI 109 Directory of forestryforestry researchresearch organizations,organizations, 19931993 (E)(E) 110 Proceedings ofof the Meeting of ExpertsExperts on Forestry Research.Research, 1993 (E/F/S) 1111 1 1 Forestry policies inin the Near EastEast r regionegion - - AnaAnalysislysis andand synthesis, synthesis, 19931993 IEI(E) 1112 12 Forest resources assessmentassessment 19901990 - TropicalTr,opical countries,countries. 19931993 (E) (E) 113113 Ex situ storage of seeds, pollen andand in in vitrovitro culturescultures ofof perennial woodywoody plant species, 19931993 (E) (E) 114 Assessing forestry project impacts: issuesissues and strategies.strategies, 1993 (E(E FF S)S) 1151 15 Forestry policies of selected countries in Asia and the Pacific, 19931993 (E) (E) 116 Les panneaux àill base de bois, 19931993 (F) (F) 117 Mangrove forest managementmanagement guidelines,guidelines, 19941994 (E) (E) 118 Biotechnology in forest treetr~e improvement,improvement, 19941994 (E) (E) 119 Les produits bois reconstitués,reconstitu~s, liantsli ants et environnement,environnement, 19941994 (F)IF) 120 Decline and diebackdieback ofof treestrees andand forests forests -- A global overview.overview, 19941994 (E) (E) 121 EcologfaEcología y enseiianzaenseñanza ruralrural - ManualManual parapara profesoresprofesores ruralesrurales deldel áreaarea andina.andina, 1994 (S)(S) 122 Readings inin sustainable forestforest management, 1994 (El(E) 123 Forestry education - NewNew trendstrends andand prospects,prospects, 1994 (ElE F) 124 Forest resources assessmentassessment 1990 1990 - GlobalGlobal synthesis,symhesis, 19951995 (E)(E) 125 Forest products prices 1973-1992, 1995 1995 (E/F/S) (E /F/SI 126 Climate change, forestforest and forestforest management - - an overview, 19951995 (E)(E)

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