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An Investigation of Forest Ecosystem Health in Relation to Anthropogenic Disturbance in the Southwestern Mau Forest Reserve, Kenya A dissertation for the Award of the Degree of Doctor of Natural Sciences (Dr. rer. nat.) Faculty of Chemistry and Biology University of Bremen Presented by Obati, Gilbert Obwoyere An Investigation of Forest Ecosystem Health in Relation to Anthropogenic Disturbance in the Southwestern Mau Forest Reserve, Kenya A dissertation for the Award of the Degree of Doctor of Natural Sciences (Dr. rer. nat.) Faculty of Chemistry and Biology University of Bremen Presented by Obati, Gilbert Obwoyere First Supervisor: PD Dr. Broder Breckling Second Supervisor: Prof. Dr. Martin Diekmann Submitted on 3rd August, 2007 Date of conferrment 18th September, 2007 Gilbert Obwoyere. Obati Declaration Statement according to §6 Final Examination Regulation of the University of Bremen for the Degree of Dr of Natural Science (Dr. rer. nat.). I herewith declare and confirm that I have elaborated my dissertation titled An Investigation of Forest Ecosystem Health in Relation to Anthropogenic Disturbance in the South-western Mau Forest Reserve, Kenya Single-handed and without using other sources other than those mentioned herein. _________________________ ___________________ Place and Date Signature ii Forest Ecosystem Health-SW Mau, Kenya Abstract The dissertation describes investigations carried out from September 2005 to August 2006 to assess forest ecosystem health in relation to human disturbance in the Southwestern Mau forest reserve Kenya. The study involved the determination and comparison of tree species composition and structure, regeneration potential and capacity, litter production and nutrient fluxes between disturbed and undisturbed sites. A socioeconomic appraisal of the inhabitants was also carried out. Forest cover change analysis of the greater Mau forest was done for the period between 1984 and 2003 using Landsat satellite images. A total of 24 families, 34 genera and 37 woody species comprising mainly trees were enumerated. There were 20 families in the undisturbed sites while 21 were present in the disturbed sites. In undisturbed sites, 30 species belonging to 29 genera were recorded while 29 species from 27 genera were tallied in the disturbed sites. The mean species richness was higher in the disturbed sites. Undisturbed sites had a lower proportion of shrubs and under storey trees with a higher frequency of over storey trees. Both sites had high number of seedlings and wildings. Regarding survival and recruitment from seasonal seed rain, disturbed sites had significantly higher mean species richness. Germinations from seasonal seed rain indicated higher mean seedling species richness in disturbed plots while seedling density was significantly higher in undisturbed plots. No significant mean differences in species composition were recorded from the seed bank trials. A higher amount of fine litter was collected in disturbed plots with insignificant mean differences with regard to K, C and N content between the sites. There were no significant mean differences in the C: P, ratios whereas undisturbed plots had significantly lower mean C: N ratios. Within stand mean nutrient use efficiency for C, N, P, K, and Ca were lower in the undisturbed plots. Survey results indicated that several tree species that were once common or dominant in the area were increasingly becoming rare. Increase in human population, firewood collection, agricultural expansion, land subdivision among others were ranked as important causes of forest degradation. Positive significant correlations were reported between the definition of provision of services, forest condition, provision of goods, the adequacy of goods provided and ecosystem health. However, a significant negative correlation was reported for the values attached to the current land use. The presence of disturbance indicator species like Neoboutonia macrocalyx, Croton megalocarpus and Vernonia auriculifera in the vegetation community indicates considerable levels of human disturbance in the reserve representing retrogression in the vegetation succession. The vertical stratification of the forest reserve depicts secondary growth in the reserve. The potential for natural regeneration of trees after natural or anthropogenic disturbance exists despite a poor soil seed bank. High litter annual turn over in disturbed sites, coupled with lower nutrient content and nutrient use efficiency as well as higher fine litter C: N and C: P ratios defines them as poorer sites. A chronological degradation in the condition of the forest over time is apparent with current land uses having negative significant effects. Thematic change and image difference analysis indicated a significant change in closed canopy forest. iii Gilbert Obwoyere. Obati Acknowledgements First, I give honour and glory to God for his unfailing gift of life and blessings throughout the entire project period. Secondly, my sincere gratitude is due to my supervisors PD. Dr. Broder Breckling and Prof. Dr. Martin Diekmann for their unconditional support and specifically Dr Breckling for his day today interactions during the course of this project. May I take this opportunity to also sincerely appreciate the support of Prof. Dr. Juliane Filser Head, Department of General and Theoretical Ecology. I would also like to extend my appreciation to colleagues at the Department of General and Theoretical Ecology University of Bremen for their insights and encouragement during the entire period. I am also indebted to Ms Marion Ahlbrecht of the Department of Vegetation and Evolutionary Ecology University of Bremen who directly assisted in the analysis of litter samples. The computer systems administrator Mr Falko Berger was of more of a brother in all my computer related work at the UFT, to him is a handful of thanks. My sincere gratitude is due to Professor A A Aboud and Dr. M. Karachi of the Department of Natural Resources Egerton University, Kenya for their valuable support during the fieldwork stage. Am also indebted to the technicians at Kenya Agricultural Research Institute (KARI-Njoro) National Plant Breeding Centre and the department of Soil Science Egerton University for processing of the litter samples. I owe gratitude to staff of the Kenya Forest Service, Mara Mara and Itare forest stations specifically Messrs Kevin K. Sitieney and Martin M. Marete for their tireless efforts during the fieldwork. Likewise, I would like to thank Gladys Chepkirui and Anita Chepkirui for their assistance in administering the questionnaires. Am greatly indebted to my family, my wife (Rodah) and daughters (Faith and Anne) for their constant prayers, support and encouragement. It was not easy being away from them when in Bremen Germany. Finally, I acknowledge the Deutscher Akademischer Austausch Dienst (DAAD) (German Academic Exchange Service) who financed the whole project. iv Forest Ecosystem Health-SW Mau, Kenya Dedicated to My Late Mother Jessicah Vihenda Obati and my Family Rodah Afandi Obwoyere, Faith Vihenda Obwoyere and Anne Neema Obwoyere v Gilbert Obwoyere. Obati Table of contents Declaration ........................................................................................................ii Abstract ............................................................................................................iii Acknowledgements ..........................................................................................iv Table of contents..............................................................................................vi List of tables .....................................................................................................ix List of figures.................................................................................................... x List of symbols and acronyms .........................................................................xii 1. INTRODUCTION................................................................................................. 1 1.1 STATEMENT OF THE PROBLEM ................................................................. 4 1.2 CONCEPTUAL FRAMEWORK ...................................................................... 5 1.3 RESEARCH OBJECTIVES ............................................................................ 9 1.3.1 Broad objective........................................................................................ 9 1.3.2 Specific objectives................................................................................... 9 1.3.3 Hypotheses ........................................................................................... 10 2. BACKGROUND TO THE STUDY AREA.......................................................... 12 2.1 THE EAST AFRICAN MONTANE FOREST ECOREGION........................... 12 2.1.1 Vegetation and biome type.................................................................... 12 2.1.2 Biogeographical history ......................................................................... 13 2.1.3 Current status........................................................................................ 14 2.1.4. Montane forest cover in kenya ............................................................. 15 2.2 LAND USE AND VEGETATION COVER IN KENYA .................................... 17 2.2.1 Extent and distribution of indigenous natural forests ............................. 18 2.3 FOREST MANAGEMENT IN KENYA POLICY FRAMEWORK .................... 19 2.4

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