Floristic Composition, Structural Analysis and Land Use/Land Cover Change in Bore-Anferara-Wadera
Total Page:16
File Type:pdf, Size:1020Kb
Floristic Composition, Structural Analysis and Land Use/Land Cover Change in Bore-Anferara-Wadera Forest, Southern Ethiopia Mesfin Woldearegay Addis Ababa University Addis Ababa, Ethiopia June 2017 Floristic Composition, Structural Analysis and Land Use/Land Cover Change in Bore-Anferara-Wadera Forest, Southern Ethiopia Mesfin Woldearegay Ahmed A Dissertation Submitted to The Department of Plant Biology and Biodiversity Management Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (Biology: Botanical Sciences) Addis Ababa University Addis Ababa, Ethiopia June 2017 ADDIS ABABA UNIVERSITY GRADUATE PROGRAMMES This is to certify that the Dissertation prepared by Mesfin Woldearegay Ahmed, entitled: Floristic Composition, Structural Analysis, and Land Use/Land Cover Change in Bore- Anferara-Wadera Forest, Southern Ethiopia, and submitted in partial fulfillment of the Requirements for the Degree of Doctor of Philosophy (Biology: Botanical Sciences) complies with the regulations of the University and meets the accepted standards with respect to originality and quality. Signed by Research Supervisors: Name Signature Date 1. __________________________ _________________ _____________ 2. ___________________________ _________________ _____________ 3. ____________________________ _________________ _____________ 4._____________________________ __________________ _____________ _____________________________________________ _______________ Chair of Department or Graduate Programme Coordinator Abstract Floristic Composition, Structural Analysis and Land use/Land Cover Change in Bore- Anferara-Wadera Forest, Southern Ethiopia Mesfin Woldearegay Ahmed, Ph.D. Dissertation Addis Ababa University, 2017 This study was conducted in Bore-Anferara-Wadera forest, southern Ethiopia, to investigate the floristic composition, vegetation structure, regeneration status and land use/land cover change. Vegetation data were collected from 112, 30 m x 30 m sample plots laid for trees at every 400 m distance along line transects and 5 m x 5 m and five 1 m x 1 m subplots for saplings and herbs, respectively. The regeneration status of woody species was assessed by employing total count of all seedlings within the main sample plot. Environmental variables such as altitude, slope, and exposure were measured in each sample plot. Soil samples were taken from two layers (0-25 and 25-50 cm) at five points in each sample plot and soil sample from these five points were mixed to form a composite sample. In each sample plot, woody species ≥ 3 m were counted and cover abundance values estimated as well as height and diameter at breast height were measured. Hierarchical cluster analysis was used to identify plant communities and synoptic values for identification of the dominant species for naming plant communities. Density, frequency, basal area and importance value index (IVI) of woody species were also computed. Shannon-Wiener diversity index was used to assess species richness and evenness. Sorensen's similarity coefficient was used to measure similarities among communities and between Bore-Anferara-Wadera and eight Afromontane forests in Ethiopia. Canonical correspondence analysis (CCA) was used to assess the relationship between plant community types and environmental variables. Moreover, three periods land sat images (1986 TM, 2000 ETM+ and 2014 OLI/TIRS) were acquired and analyzed by using remote sensing and GIS technologies to generate information on the temporal changes in land use and land cover types. A total of 136 vascular plant species belonging to 119 genera and 63 families were recorded. About 4.4% of the species were endemic to Ethiopia and 11.8 % of the species were new records for the Sidamo floristic region of the flora area. The overall Shannon-Wiener diversity and evenness values of Bore- Anferara-Wadera forest were 3.84 and 0.78, respectively. Size class distribution of woody species across different DBH and height classes indicated the relatively high proportion of individuals at lower classes, indicating impacts of past disturbance. Analysis of population structure and regeneration status of the forest revealed various patterns of population dynamics where some species were represented by few mature plants only suggesting that they are on the verge of local extinction and thus immediate conservation measures should be taken. Community classification using the free statistical software R version 3.1.1 resulted in four, namely Acanthus eminens - Dracaena afromontana, Syzygium guineense subsp. afromontanum - Ocotea kenyensis, Pouteria adolfi-friederici - Psychotria orophila and Scolopia theifolia - Teclea nobilis community types. Canonical correspondence analysis (CCA) result showed that altitude and slope were among the main environmental variables in determining patterns of species distribution and plant community formation. The results of land sat image iii analysis revealed that agricultural land and built up area are expanding rapidly at the expense of other land use and land cover types. Forest and shrub land areas have declined drastically over the last 28 years. Population pressure, deforestation, land tenure system, and forest fire were the main driving forces responsible for the change in land use and land cover types in the study area. Therefore, a joint management and conservation measures should be taken by the government, local people and other stakeholders in order to reduce and/or stop the fast rate of vegetation cover declining and sustainable utilization of the forest resources in the study area. Keywords: Anferara, Biodiversity, Conservation, Land use/land cover, Plant community iv DEDICATION I would like to dedicate this dissertation to my wife Mekdes Gerawork and my children Samuel and Hemen Mesfin for their unreserved support, encouragement and patience over the years, and to my parents who did not enjoy formal education but strongly committed to teach their children hoping that their future will be better off. v ACKNOWLEDGMENTS I would like to express my sincere gratitude to my supervisors Prof. Zerihun Woldu and the late Prof. Ensermu Kelbessa for their unreserved guidance, comments, support and effective follow-up of the research work. I am also very much grateful for their openness and friendly approach, encouragement, valuable suggestions and effective academic assistance in the whole progress and completion of my Ph.D. work. I would like to thank Debre Birhan University (DBU) for sponsoring me for this Ph.D. study and provision of additional financial support for the completion of the study. I would like to extend my thanks to the Graduate Programmes of Addis Ababa University for funding the cost of all the research work. I am obliged to pass my deepest thanks to Oromia Region Forest and Wildlife Enterprise, Borena-Guji Forest and Wildlife Enterprise, Adola Wayu District, Anasora District and Wadera District Administration offices for their hospitality and permission to conduct this research project. I greatly acknowledged the Kebele Administration officers of the study sites for their support and assistance in the field work. I would like to extend my deepest gratitude to the Department of Plant Biology and Biodiversity Management, Addis Ababa University (AAU) for facilitating the study; the technical staff members of the National Herbarium (ETH) for their kind help for all aspects of the herbarium work; the National Meteorological Service Agency of Ethiopia and Ethiopian Mapping Agency for providing meteorological data and map of the study area, respectively. vi The local people inhabiting in and around the forests are greatly acknowledged for unreservedly sharing with me their knowledge of the wild flora and possible driving forces for the land use and land cover change that occurred in the study area and for their kind assistance during data collection. Ato Dagne Negussie (Head of Forest Development & Utilization Department in Borena-Guji Forest and Wildlife Enterprise), Ato Tepissa Girja (Head of Culture & Tourism at Adola Wayu District) Ato Teglu Abate (Expert at Borena-Guji Forest and Wildlife Enterprise) and Ato Ashebir Abebe (Expert at Borena- Guji Forest and Wildlife Enterprise) are truly acknowledged for their valuable information in land use and land cover change trends and the natural vegetation in the study area. I am very thankful to my friend Dr. Ermias Lulekal for giving valuable comments by reading the dissertation besides his encouragement, support, and advice on how to tackle the course work and the research activities to this end. I also extend my heartfelt thanks to Ato Yosef Samuel for his assistance in land use and land cover change data analysis, kind hospitality at his home during field work and continuous support and advice to accomplish this Ph.D. work. My friend Ato Amanuel Abate is also truly acknowledged for providing comments by reading the land use and land cover change part of the dissertation. I also thank Ato Solomon Tadesse, DBU staff member, for allowing me to use his office during dissertation write-up. I am very much indebted to my wife Mekdes Gerawork for her devotion to take all the family burden and household responsibility patiently beside her support, encouragement vii and prayers throughout the study period, and my children Samuel and Hemen Mesfin for their love. My father Woldearegay Ahmed, my mother Worknesh Tegegne, my brothers and sisters Bahirwossen W/aregay, Tesfaye W/aregay, Belay W/aregay, Zufan W/aregay, Hana W/aregay, Tweodros