Bush Encroachment in Namibia
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Bush encroachment in Namibia i BUSH ENCROACHMENT IN NAMIBIA Report on Phase 1 of the Bush Encroachment Research, Monitoring and Management Project JN de Klerk Bush encroachment in Namibia ii © Ministry of Environment and Tourism, Government of the Republic of Namibia All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission. No paragraph of this publication may be repro- duced, copied or transmitted save with written permission. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. First published 2004 Language editor: Sandie Fitchat Cover design: DV8 Layout: Asser Karita Cover photo: Taken near Ovitoto, showing overutilisation and bush encroachment Ministry of Environment and Tourism Directorate of Environmental Affairs Private Bag 13346 Windhoek Namibia Tel (061) 249015 ISBN 0–86976–620–1 Printed by John Meinert Printing (1999) Bush encroachment in Namibia Contents iii ACKNOWLEDGEMENTS VII LIST OF ABBREVIATIONS IX EXECUTIVE SUMMARY X THE CAUSES OF BUSH ENCROACHMENT X THE IMPACT OF BUSH ENCROACHMENT XI THE MAGNITUDE AND OCCURRENCE OF INVADER SPECIES XII POLICIES AND LEGISLATION XIII PROPOSAL OF A LONG-TERM RESEARCH, MONITORING AND MANAGEMENT STRATEGY XIV CONCLUSION XVI CHAPTER 1: PROBLEM STATEMENT 1 1.1 BUSH ENCROACHMENT AS AN INTEGRATED PART OF DESERTIFICATION 2 1.2 MAGNITUDE AND OCCURRENCE OF INTRUDER BUSH 3 1.3 CLIMATIC FEATURES 5 1.4 PEOPLE AFFECTED 8 1.5 INTRODUCING THE BUSH ENCROACHMENT RESEARCH, MONITORING AND MANAGEMENT PROJECT 8 REFERENCES 9 CHAPTER 2: CAUSES OF BUSH ENCROACHMENT 11 2.1 PRIMARY DETERMINANTS 13 2.1.1 Walter’s Two-layer Model 14 2.1.2 State and Transition Model 14 2.1.3 Applicability of the two hypotheses 15 2.2 SECONDARY DETERMINANTS 15 2.2.1 Fire 15 2.2.2 High stocking rates 19 2.2.3 Herbivory 23 2.2.4 Biological interactions 24 2.2.5 Trees and grass modifying primary determinants 24 2.2.6 Bush–grass competition 26 2.2.7 Effect of tree competition on trees 30 2.2.8 Effect of clearing on animal performance 30 2.2.9 Temperature 31 2.2.10 Droughts and rainfall 31 2.2.11 Distribution of seeds 32 2.2.12 Increased atmospheric CO2 concentrations and climate change 37 REFERENCES 37 CHAPTER 3: ENVIRONMENTAL AND ECONOMIC IMPACTS OF BUSH ENCROACHMENT 45 3.1 INTRODUCTION 46 3.2 IMPACT ON SOIL TEMPERATURE 47 3.3 IMPACT ON SOIL MOISTURE 47 3.4 IMPACT ON SOIL FERTILITY 50 3.5 BIODIVERSITY 50 3.5.1 Impact of bush control measures on vertebrates, invertebrates and plants 53 3.6 LAND PRODUCTIVITY 58 3.6.1 Carrying capacity 58 3.6.2 Browse, available browse and its relation to tree density 62 3.6.3 Impact of bush encroachment on woody biomass 64 3.7 HABITAT 66 3.8 CONCLUSIONS 66 REFERENCES 67 Bush encroachment in Namibia CHAPTER 4: VEGETATION COMPOSITION AND LAND PRODUCTIVITY 75 iv 4.1 BUSH DENSITY AND ITS INTERACTION WITH LAND PRODUCTIVITY 76 4.1.1 Problem bush 78 4.1.2 Thorny problem bushes 82 4.1.3 Non-thorny problem bushes 84 4.1.4 Fodder bushes 86 4.1.5 Total bushes and trees 86 4.1.6 Dead bushes and trees 88 4.1.7 Conclusions 89 4.2 MAPPING HISTORICAL AND PRESENT INFORMATION ON BUSH DENSITY AND COMPOSITION 90 4.2.1 Historical situation 90 4.2.2 Present situation: Results and analysis 92 4.3 CONCLUSIONS 130 REFERENCES 132 CHAPTER 5: OVERVIEW OF POTENTIAL METHODS TO COMBAT INVADER BUSH 133 5.1 CHEMICAL TREATMENT 134 5.1.1 Results obtained with chemical treatment 134 5.1.2 Practical application of chemicals 137 5.1.3 Aftercare measures 140 5.1.4 Preventive techniques 141 5.1.5 Environmental and health risks 141 5.2 BIOLOGICAL CONTROL 144 5.2.1 The use of browsers 144 5.2.2 Natural die-off 147 5.2.3 Natural enemies 148 5.2.4 Fire 150 5.3 MECHANICAL CONTROL 156 5.3.1 Stumping/felling 156 5.3.2 Bulldozing 158 5.4 CONCLUSIONS 159 5.4.1 General 159 5.4.2 Chemical treatment 159 5.4.3 Biological 160 5.4.4 Mechanical 160 REFERENCES 161 CHAPTER 6: INDICATORS AND THE MONITORING SYSTEM 167 6.1 INTRODUCTION AND TERMS OF REFERENCE 168 6.2 INDICATORS 168 6.2.1 Introduction 168 6.2.2 Criteria for good indicators 168 6.2.3 Methodology 169 6.2.4 Discussion 170 6.2.5 Recommendations 173 6.3 MONITORING SYSTEM 174 6.3.1 The context of monitoring 174 6.3.2 Who should do the monitoring? 174 6.3.3 Simple vs. reliable measurements 174 6.3.4 Need for statistical analysis 174 6.3.5 Subjective versus objective measurements 175 6.3.6 Need for benchmarks 175 6.4 TRIAL GROUND MONITORING 175 6.4.1 Introduction 175 6.4.2 Conclusion 176 6.4.3 Proposed monitoring 176 6.4.4 Recommendations 177 6.5 EXPERT SYSTEM DEVELOPMENT 178 Bush encroachment in Namibia 6.5.1 Introduction 178 6.5.2 Decision-making with the expert system 179 v 6.5.3 Recommendations regarding the use of the expert system 180 6.6 REMOTE SENSING 180 6.6.1 Satellite remote sensing 180 6.6.2 Aerial photography 181 6.6.3 Recommendations 181 6.7 DATA STORAGE AND DISTRIBUTION 181 6.7.1 Recommendations 181 REFERENCES 181 CHAPTER 7: SOCIO-ECONOMIC FACTORS AND INCENTIVES INFLUENCING FARMERS IN COMBATING BUSH ENCROACHMENT 183 7.1 INTRODUCTION 184 7.2 METHODOLOGY 184 7.3 BUSH CLEARING IN NAMIBIA 185 7.3.1 Economic viability of applying different bush-clearing methods 185 7.4 SOCIO-ECONOMIC FACTORS INFLUENCING FARMERS’ PARTICIPATION IN PHASE 2 OF THE PROJECT 186 7.4.1 Costs related to bush clearing 186 7.4.2 Limited or lack of capital 187 7.4.2 Availability of land to lease 187 7.4.3 Markets for bush by-products 187 7.4.4 Availability of labour 187 7.4.5 The land tenure policy 188 7.4.6 Awareness of clearing methods and economic benefits 188 7.4.7 Summary 188 7.5 COST-BENEFIT ANALYSIS AND ASSESSMENT 188 7.5.1 The need for assistance in combating bush encroachment 189 7.5.2 Nature and magnitude of assistance required by farmers 189 7.5.3 Incentives for farmers to participate in Phase 2 194 7.5.4 Employment opportunities 195 7.5.5 Summary of the main findings 197 7.6 SKILLS TRAINING PROGRAMME FOR AGRICULTURAL EXTENSION OFFICERS, RESEARCHERS, TECHNICIANS, AND WORKERS 197 7.6.1 Setting priorities 197 7.6.2 Summary 198 7.7 CONCLUSIONS 198 REFERENCES 199 CHAPTER 8: REVIEW OF THE POLICY ENVIRONMENT AND PROPOSALS FOR POLICY REFORM 201 8.1 SCOPE OF THE STUDY 202 8.2 METHODOLOGY 202 8.3 BUSH ENCROACHMENT IN THE WIDER CONTEXT 202 8.4 POLICIES AND LEGISLATION 203 8.4.1 The Constitution 203 8.4.2 National Agricultural Policy 204 8.4.3 National Drought Policy and Strategy 205 8.4.4 Subdivision of Agricultural Land Act, 1970 (No. 70 of 1970) 206 8.4.5 Fencing Proclamation 57 of 1921 206 8.4.6 Soil Conservation Act, 1969 (No. 76 of 1969) 207 8.4.7 Weeds Ordinance 19 of 1957 207 8.4.8 National Land Policy 207 8.4.9 National Resettlement Policy 208 8.4.10 Agricultural (Commercial) Land Reform Act, 1995 (No. 6 of 1995) 208 8.4.11 Land tax 209 8.4.12 Communal Land Reform Act, 2002 (No. 5 of 2002) 209 8.4.13 Namibia Forestry Strategic Plan 210 8.4.14 Namibia Forest Development Policy 211 Bush encroachment in Namibia 8.4.15 Namibia Forest Policy Statement 212 8.4.16 The Forest Act, 2001 (No. 12 of 2001) 212 vi 8.4.17 National Guidelines on Fires and Fire Management 213 8.4.18 Poverty Reduction Strategy for Namibia 214 8.5 Findings and recommendations 215 REFERENCES 217 CHAPTER 9: LONG-TERM STRATEGY MANAGEMENT FOR BUSH CONTROL 221 9.1 Result 1: Environmentally sound principles of bush Control are established and adhered to at local and national levels 226 9.1.1 Ecological considerations/principles 226 9.1.2 Critical Performance Areas 228 9.1.3 Guidelines for sustainable harvesting 229 9.1.4 Target species 230 9.2 Result 2: Bush encroachment is controlled in An economically and ecologically sustainable way 231 9.2.1 Methods to control invader bush 231 9.2.2 Aftercare measures 238 9.2.3 Restoration technologies 240 9.2.4 Addressing research needs 240 9.3 Result 3: The integrated information and monitoring System is operational at national and farm level 241 9.3.1 Maintenance of a Bush Expert Decision Support System 241 9.3.2 Establishment of a monitoring system for measuring changes in woody vegetation 242 9.3.3 Capacity-building to manage and maintain the Expert Systems 245 9.4 Result 4: An enabling institutional framework and operating Policy environment for bush-based enterprises is established, And quality control and marketing mechanisms for efficient Utilisation of bush-based products are improved 246 9.4.1 The present policy environment 246 9.4.2 Creating a favourable policy environment 246 9.4.3 Introduction of socio-economic incentives 249 9.5 Result 5: Capacity is in place within relevant government Ministries and the commercial and communal sectors, To manage and utilise woodlands in a sustainable way 252 REFERENCES 253 Bush encroachment in Namibia Acknowledgements vii On behalf of the Government of the Republic of Namibia, in particular the farming communities in the affected areas, we express our sincere gratitude to the Government of the Republic of Finland for its generous financial contribution that enabled the Bush Encroachment Research, Monitoring and Management Project to be launched.