People and Cattle: Agents of Ecological Change in a Dry Montane Forest, Samburu District, Kenya
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People and cattle: agents of ecological change in a dry montane forest, Samburu District, Kenya Phillida C. Chenevix Trench Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy University College London University of London March, 1997 ProQuest Number: 10045716 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10045716 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 To Mum and Arthur Abstract In this thesis, I investigate the ecological impact of Samburu pastoralists and their cattle in an area of dry montane forest on the Lerroki Plateau in Samburu District, Kenya. The thesis focuses on the effects of cattle on tree species diversity and closed canopy forest cover inside the Leroghi Forest Reserve. The importance of the closed canopy forest to cattle during dry periods is demonstrated by means of cattle censuses, cattle follows, faecal pellet surveys and informal interviews. A variety of ecological methodologies were employed to compare plant population structure and diversity in areas of forest under varying intensities of cattle use. Little evidence of long term changes in the overall population structure or diversity of tree species was found in association with cattle grazing. Interpretation of aerial photographs from 1963 and 1993 found no evidence of forest degradation or retreat under grazing pressure. Multi-round surveys found little difference in frequency of general wild resource use by local communities in relation to the socio-economic status of the sub-household. However, the frequency of collection of marketable forest products was significantly higher in those villages with easier access to the main market at the District capital, Maralal. Comparison of aerial photographs found the degree of forest degradation and clearance over the last thirty years correlated positively with proximity to Maralal. The main exception was a large area of closed canopy forest north of Maralal which had been destroyed by fire in the 1980’s. These findings show that commercial extraction is a more important influence than cattle on forest structure and composition. These results have important implications for forest managers in dryland areas. The success of forest conservation within the Leroghi Forest Reserve has its roots in shared management objectives of the local pastoral community and the Forest Department, and the absence of long term damage to forest by cattle using the forests during the dry season. It is the absence of shared management objectives that threatens the long term survival of the forests located outside the reserve. Acknowledgements I am grateful to the Overseas Development Association Associate Professional Officers Scheme for funding this research both in the field and at UCL. The UCL Graduate Fund also provided extra funding which enabled the completion of the aerial photograph interpretation. I would like to thank the Kenya Indigenous Forest Conservation Programme (KEFCON) team in Nairobi with whom this study began. I am particularly grateful to Paul Wachiori Muhoro and Dennis Milewa who carried out the aerial photograph interpretation and helped to draw many of the maps found in this thesis; Nick Hodgson and Josphat for their endless patience as I battled with MAP INFO; Glyn Davies, Lucy Emerton and Liz Wily for their technical advice and insights as I was getting started; Abert Luvanda from KEFRI; and Peter Wass for supporting the research and helping it to reach its final phase with the Bellerive Foundation. The KIFCON team at the National Museums of Kenya were a constant source of technical support and friendship, both in the field and in Nairobi and I would especially like to acknowledge Onesmus Mwangangi, Philip Kamau, Mwangi, Kwumbai and Beatrice Miringu for making wet forests and windy camp sites fun places to be. Onesmus Mwangangi, Philip Kamau and Beatrice Miringu carried out all species identification, together with Lenaardo Lelesiit from Ngorika, and prepared the species lists found at the end of this thesis. I was able to complete the study thanks to Chris Davey and Tony Potterton at the Bellerive Foundation, who also gave me the very special opportunity to see the preliminary results of the study used in establishing the Lerroki Forest Conservation Project. It is impossible to express the gratitude I feel towards all the people I worked with at Lerroki. I will always remain indebted to the many people who made me so welcome at Seketet, Ngorika and Lpartuk and made this study possible. My very special thanks go to Jackson and Jennifer Lenaola, who welcomed me into their home at the very start of study and remained friends throughout; to Jackson, James and Julius Lenaola for their untiring commitment and good humour in developing and carrying out the household surveys with me; and to Lenaardo Lelesiit, Moses Leseiya and Lemunen at Ngorika who braved elephants, stinging nettles and rain and shared many cups of chai in Saanata in the course of the vegetation surveys. I owe much to their insights and will always have happy memories of measuring trees. I would also like to extend my heartfelt thanks to Assistant Chief William Lelechep and his family, Moses Lentiipo, Lemunen and Letowon family at Ngorika and to Councillor Lenyarwa, Lilian Lebarakwe and Chefta Lentirash at Lpartuk. The Forest Department at Maralal gave a great deal of support to the study and I am very grateful to Mr Njenga, District Forest Officer and Mr Lenkaak, Forest Officer for all their time and interest. At UCL, my supervisor, Katherine Homewood has given me endless encouragement, support and constructive criticism, from the early days of project proposals to final editing, for which I am forever grateful. Tim Allot helped me overcome my instinctive aversion to multivariate analysis and turned it into something almost fun. Many people at the Biological Anthropology Department have helped in the evolution of this thesis. Special thanks to the three Dans (Sellen, Nettle and Brockington), Fred Brett, Dawn Hartley, Simon Strickland, Yvette and Derek, Sian, Emmanuel, Jo, Alan, Guy, Adam, Tanya and finally to Sara Randall for the challenges on and off the squash court that kept me going (you owe me £19.90). The Sankardass and Inamdar family were always warm and welcoming in Nairobi and I I am forever grateful for their generosity and support. Thanks to Caroline, Harry & Dougall for giving me a place to stay in London and keeping me current with the EastEnders plot line, to Mark (for pointing out the butterflies), and to Clare for not giving me as hard a time as you gave Amar. My greatest thanks of all must go to Amar and to Joe for showing me what life can hold if you just reach out for it. TABLE OF CONTENTS Abstract 2 Acknowledgements 3 Table of Contents 5 List of figures 10 List of tables 12 1. INTRODUCTION 15 1.1 SUMMARY 15 1.2 THE STRUCTURE OF THE THESIS 17 1.3 CONTEXTUAL FRAMEWORK 18 1.3.1 Dry Montane Forest in Kenya 18 1.3.2 Forests, savannas and disequilibrium 18 1.3.3 Cattle and closed canopy forests 21 1.3.4 Cattle, Forests and Forest Administration 22 1.3.5 Communities and closed canopy forests 23 1.3.6 Forest management 24 1.3.7 Measuring sustainability 25 1.4 HYPOTHESES AND PREDICTIONS TO BE TESTED 29 1.5 CONCLUSION 30 2. STUDY SITES, METHODOLOGY AND APPROACH 31 2.1 INTRODUCTION 31 2.2 THE LERROKI PLATEAU 31 2.2.1 Introduction 31 2.2.2 Topography and soil 32 2.2.3 Climate 34 2.2.4 Economic Environment 40 2.2.5 The Population 40 2.2.6 Pastoralists and paradigm shifts 43 2.2.7 The Samburu and the Lerroki Plateau 46 2.2.8 Land tenure on the Lerroki Plateau 52 2.2.9 Land use on Lerroki 58 2.2.10 The Lerroki Forests 59 2.2.11 Livestock on Lerroki 64 2.3 THE STUDY SITES 71 2.3.1 The study villages 71 2.3.2 The Forests 76 2.4 STUDY METHODOLOGY 80 2.4.1 Approach 80 2.4.2 Changes in area o f woody vegetation in and around the Leroghi Forest Reserve 80 2.4.3 Wild resource use and users. 81 2.4.4 Cattle as forest users 83 2.4.5 The impact of cattle 84 2.4.6 Field Assistants 85 2.4.7 Language 86 3. CATTLE AND FORESTS 88 3.1 INTRODUCTION 88 3.2 CATTLE AND FORESTS - EVIDENCE FROM THE LITERATURE 88 3.3 CATTLE AND FORESTS - EVIDENCE FROM THE GROUND 90 3.3.1 Methods 91 3.3.2 Results 95 3.4 DISCUSSION 104 3.5 CONCLUSIONS 106 4. THE EFFECT OF CATTLE ON CLOSED CANOPY FOREST STRUCTURE AND DIVERSITY 107 4.1 INTRODUCTION 107 4.2 THE IMPACTS OF CATTLE ON VEGETATION - A REVIEW 108 4.2.1 Mechanical impacts of cattle 109 4.2.2 Cattle, fire andforests 110 4.2.3 Forests and plant population structure 114 4.2.4 Cattle grazing and species diversity 117 4.3 GENERATING HYPOTHESES 118 4.4 METHODS 121 4.4.1 Methods - Tree density, stand structure and species composition 121 4.4.2 Methods - Seedling growth and survival and herbaceous cover 129 4.5 DATA ANALYSIS 132 4.5.1 Tree Density 132 4.5.2 Seedling density 133 4.5.3 Stand structure 133 4.5.4 Species diversity 133 4.5.5 Evidence of browsing of seedlings and other damage 139 4.5.6 Herbaceous cover 140 4.6 RESULTS: TREE DENSITY, STAND STRUCTURE AND SPECIES COMPOSITION 141 4.6.1 Tree Density 141 4.6.2 Tree damage 142 4.6.3 Seed!ing density 142 4.6.4 Seedling damage 143 4.6.5 Stand Structure 144 4.6.6 Species Diversity 151 4.7 HERBACEOUS COVER 155 4.8 DISCUSSION 157 4.8.1 Summary o f key resul ts 157 4.8.2 The hypotheses tested 160 4.8.2 Comparison with other studies 162 4.9 CONCLUSIONS 164 5.