Ecology and Utilisation of Harpagophytum procumbens (Devil's Claw) in Southern Africa Plant Species Conservation Monographs 2 Results of the R+D Project 80086005 Berit Hachfeld Federal Agency for Nature Conservation Bonn - Bad Godesberg 2003
Content List of Figures 9 List of Tables 11 Abbreviations 13 Acknowledgements 14 Preface 15 1 Introduction - Biodiversity and medicinal plants 17 2 Aim of the study & research objectives 20 3 Systematics of Harpagophytum 24 3.1 Taxonomy and evolution 24 3.2 Scientific and common names 25 4 Distribution of Harpagophytum 27 4.1 Distribution in southern Africa 27 4.2 Distribution in National Parks 28 5 The natural environment of Harpagophytum 29 5.1 Physiography 29 5.2 Climatic conditions 29 5.2.1 Precipitation 29 5.2.1.1 Namibia 29 5.2.1.2 South Africa 31 5.2.2 Air temperature and relative air humidity 31 5.2.3 Climatic regions 31 5.3 Habitat requirements of Harpagophytum 31 5.3.1 Namibia 31 5.3.2 South Africa 33 5.4 Vegetation 33 5.4.1 Namibia 33 5.4.1.1 Biome classification 33 5.4.1.2 Vegetation types 33 5.4.2 South Africa 35 5.4.2.1 Biome classification 35 6 The socio-economy of Harpagophytum 36 7 The drug Harpagophyti radix 37 7.1 Harpagophytum in Pharmacopoeias 37 7.2 Constituents of Harpagophytum 38 7.2.1 Constituents of Harpagophytum procumbens 38 7.2.2 Constituents of Harpagophytum zevheri 39 7.3 Therapeutical effects of Harpagophvtum 40 7.3.1 Medicinal applications 40
7.3.2 Traditional uses 40 7.4 Adulterations and confusion with other species 40 8 Ecology of Harpagophytum 42 8.1 Approach 42 8.2 Methods 43 8.2.1 Field campaigns 43 8.2.2 The research sites 43 8.2.3 The documentation sheet 45 8.2.4 Applied analytical methods 46 8.3 Research areas 47 8.3.1 Regions and districts 48 8.4 Occurrence and frequency of Harpagophytum 51 8.4.1 Occurrence under different land use 51 8.4.2 Occurrence in different vegetation types 52 8.4.2.1 Namibia 52 8.4.2.2 South Africa 57 8.4.2.3 Summary and conclusions on the occurrence of Harpagophytum 60 8.5 The impact of the habitat on Harpagophytum 63 8.5.1 Harpagophytum density in different habitat types 63 8.5.1.1 Namibia 64 8.5.1.2 South Africa 65 8.5.2 Summary and conclusions on the impact of the habitat on Harpagophytum 66 8.6 The impact of soil properties on Harpagophytum 67 8.6.1 Physical soil properties 67 8.6.2 Chemical soil properties 69 8.6.3 Summary and conclusions on the impact of soil properties on Harpagophytum 70 8.7 The impact of land use on Harpagophytum 71 8.7.1 Frequency of different grazing intensity classes 73 8.7.2 Resource status and grazing intensity 74 8.7.3 Summary and conclusions on the impact of land use on Harpagophytum 77 8.8 The impact of the vegetation on Harpagophytum 78 8.8.1 Role of vegetation layers for the occurrence of Harpagophvtum 78 8.8.2 Grazing intensity and grass cover 80 8.8.3 Grass cover and resource status of Harpagophytum 81 8.8.4 Accompanying plant species 84 8.8.5 Summary and conclusions on the impact of the vegetation on Harpagophytum 85 8.9 Spatial distribution of Harpagophytum 88 8.9.1 Resource distribution on the square kilometre 88 8.9.2 Analysis of variance in the spatial distribution of Harpagophytum 91 8.9.3 Summary and conclusions on the spatial distribution of Harpagophytum 92
8.10 Reproductive effort of Harpagophytum 96 8.10.1 Flowers 96 8.10.1.1 Background information on flowers of Harpagophvtum 96 8.10.1.2 Flowering intensity 97 8.10.1.3 Flowering intensity of single individuals 99 8.10.1.4 Flowering intensity of Harpagophytum in various vegetation types 100 8.10.1.5 Impact of plant size on flowering intensity 101 8.10.1.6 Summary on the flowering of Harpagophvtum 102 8.10.2 Fruit set 103 8.10.2.1 Background information on fruits, fruit-set and dispersal of Harpagophytum 103 8.10.2.2 Intensity of fruit-set of Harpagophytum 105 8.10.2.3 Fruit-set of various vegetation types 106 8.10.2.4 Summary on the fruit set of Harpagophvtum 106 8.10.3 Seed bank 107 8.10.3.1 Background information on seeds, seed bank and germination of Harpagophytum 107 8.10.3.2 Calculation of the potential seed bank of Harpagophytum 109 8.10.3.3 Seed bank contribution in various vegetation types Ill 8.10.3.4 Summary on the seed bank of Harpagophytum 113 8.10.4 Reproductive effort of different Harpagophytum densities 114 8.10.5 Summary and conclusions on the reproductive effort of Harpagophytum 115 8.11 Utilisation of Harpagophytum 119 8.11.1 Density of harvested sites 120 8.11.2 Intensity of utilisation 120 8.1 1.2.1 Frequency of harvesting holes and Harpagophytum plants 120 8.11.2.2 Utilisation intensity in comparison to potential resource availability 123 8.1 1.2.3 Utilisation intensity in regions and provinces 124 8.11.3 Impact of harvesting on the density of Harpagophytum 127 8.11.4 Analysis of variance in the utilisation of Harpagophvtum 130 8.1 1.5 Summary and conclusions on the utilisation of Harpagophytum 130 8.12 Discussion and conclusions on the ecology of Harpagophytum 134 8.12.1 Resource availability of Harpagophytum 134 8.12.2 Reproductive effort of Harpagophytum 140 8.12.3 Utilisation of Harpagophytum 142 8.12.4 Regeneration potential 143 9 Re-documentation of Harpagophytum 145 9.1 Approach 145 9.2 Methods 146 9.2.1 Field campaigns 146 9.2.2 Methods of re-documentation 146 9.3 Research areas 147 9.4 One-year re-documentation of Harpagophytum 149 9.4.1 Results 149
9.4.1.1 Changes in Harpagophytum quantities on re-documentation sites 149 9.4.1.2 Utilisation of Harpagophytum on re-documentation sites 150 9.4.1.3 Environmental conditions on re-documentation sites 151 9.4.1.4 Reproductive effort of Harpagophytum on re-documentation sites 152 9.4.2 Summary and conclusions on the one-year monitoring of Harpagophytum 152 9.5 Three-year re-documentation of Harpagophvtum 153 9.5.1 Results 153 9.5.2 Summary and conclusions on the three-year re-documentation of Harpagophytum 158 10 I nterviews 159 10.1 Approach 159 10.2 Methods 159 10.3 Research areas 161 10.4 Results 163 10.4.1 Frequency and density of Harpagophytum 163 10.4.2 Ecology of Harpagophytum 164 10.4.2.1 The role of the abiotic environment for the occurrence of Harpagophytum 164 10.4.2.2 The role of the biotic environment for the occurrence of Harpagophytum 166 10.4.2.3 The role of land use for the occurrence of Harpagophytum 167 10.4.3 Utilisation and of Harpagophytum 168 10.4.4 Decrease of the resource Harpagophytum 1 70 10.5 Summary and conclusions on the results of the questionnaire 1 72 11 Synthesis of field studies in Harpagophytum 176 11.1 Environmental conditions of Harpagophytum 178 1 1.2 Impact of land use on Harpagophytum 180 11.3 The spatial distribution and abundance of Harpagophytum 1 80 I 1.4 Potential threats of Harpagophytum through harvest 182 I 1.5 Regeneration potential of Harpagophytum 182 I 1.6 Conclusions on the field studies in Harpagophytum 183 12 Harvesting of Harpagophytum 185 12.1 Methods 185 12.2 Harvesting 186 12.2.1 Harvesting techniques 186 12.2.2 Sustainability of harvest 188 12.2.3 Yield 189 12.2.4 Further processing 190 12.2.4.1 Processing steps undertaken by the harvester 190 12.2.4.2 Concerns regarding processing 191 12.2.5 Quality of harvested material 192 12.3 Namibia 194 12.3.1 Harvesting localities 194 12.3.2 Harvesters 194
12.3.3 Middlemen 195 12.3.4 Notable operations 196 12.3.5 South Africa 196 12.3.6 Harvesting localities 196 12.3.7 Harvesters 197 12.3.8 Middlemen 198 12.3.9 Notable operations 198 12.4 Botswana 198 12.4.1 Harvesting localities 199 12.4.2 Harvesters 199 12.4.3 Middlemen 200 12.4.4 Notable operations 200 12.5 Prices for raw material of Harpagophytum 200 12.5.1 Prices paid to the harvesters 200 12.5.2 Prices paid to the middleman 202 12.5.3 Prices paid to the exporter 203 12.5.4 Prices paid for retail products 203 12.6 Summary and conclusions on the harvesting of Harpagophytum 203 13 Cultivation and vegetative propagation of Harpagophytum 205 13.1 Cultivation trials 205 13.2 Quantity of Harpagophytum produced by cultivation 206 13.3 Possible impacts of cultivation 207 14 Trade in Harpagophytum 209 14.1 Methods 209 14.2 Namibia 210 14.2.1 Export quantities 210 14.2.2 Exporting companies 211 14.2.3 Countries of destination 212 14.3 South Africa 212 14.3.1 Export quantities 212 14.3.2 Exporting companies 213 14.3.3 Countries of destination 213 14.4 Botswana 213 14.4.1 Export quantities 213 14.4.2 Exporting companies 214 14.4.3 Countries of destination 215 14.5 The market situation 215 14.5.1 Europe 215 14.5.2 USA 216 14.5.3 Far East 216 14.5.4 Efforts to market Harpagophytum 216 14.6 Effects of trade in Harpagophytum 219
14.6.1 Area to be harvested in Namibia to meet export quantities 219 14.6.2 Area to be harvested in South Africa to meet export quantities 220 14.7 Domestic and regional trade 222 14.8 International trade 222 14.9 Organic certification 222 14.10 Intellectual property rights - patents 223 14.1 1 Conservation measures - CITES 225 14.12 Conclusions and summary on the trade in Harpagophytum 227 15 Legislation in Harpagophytum 228 15.1 Methods 228 15.2 Namibia 228 15.3 South Africa 229 15.4 Botswana 230 15.5 Conclusions and summary on the legislation in Harpagophvtum 230 16 Final discussion and conclusions 232 16.1 Spatial occurrence of Harpagophytum 232 16.2 Impact of non-sustainable harvesting on populations of Harpagophytum 233 16.2.1 Non-sutstainable harvesting in high resource areas 233 16.2.2 Non-sutstainable harvesting in low resource areas 234 16.2.3 Impact of the harvesting season 234 16.3 Incentives to get involved in the trade of Harpagophytum 235 16.4 Spatial extent of harvesting 235 16.5 Impact of the market on wild harvesting and cultivation 236 16.5.1 Decreasing market prices 236 16.5.2 Increasing market prices 237 16.6 Different incentives to sustainability 238 16.7 Namibia 239 16.7.1 Population and utilisation status of Harpagophvtum 239 16.7.2 Regeneration potential 241 16.7.3 Conclusions on the resource status in Namibia 241 16.7.4 Recommendations for Namibia 242 16.8 South Africa 243 16.8.1 Population and utilisation status of Harpagophytum 243 16.8.2 Regeneration potential 244 16.8.3 Conclusions on the resource status in Namibia 245 16.8.4 Recommendations for Namibia 245 16.9 Conclusions or is Harpagophytum threatened? 245 17 Executive Summary 248 18 Zusammenfassung 25 1 19 References 253 20 Attachments 267