Landscape Dynamics and Sustainable Land Management in Southern Ethiopia Dissertation Engdawork Assefa Graduate School Human Development in Landscape Institute of Ecosystem Research and Geoarchaeology Prüfungskommission Prof. Dr. Reiner Duttmann (Vorsitz) Prof. Dr. Hans-Rudolf Bork (Referent; Supervisor) Prof. Dr Clause Dierßen (Koreferent) PD Dr. Oliver Nelle Date of Oral Examination 1st October 2012 Table of Contents Acknowledgements ………………………………………………………………………………..i Summary …………………………………………………………………………………….iii Zusammenfassung………………………………………………………………………………….v Chapter 1 Introduction…. …………………………………………………………………1 Part I Landscape changes: patterns, driving forces and impacts in Southern Ethiopia – a case study of the Chencha and Arbaminch Areas Chapter 2 Dynamics and driving forces of agricultural landscapes.......................................5 Chapter 3 Deforestation and forest management…………………………………………..32 Chapter 4 Gully system dynamics and human impact……………………………………..58 Part II Interaction of landscape changes and sustainable land management Chapter 5 Farmers´ perceptions of land degradation and traditional land management knowledge in Southern Ethiopia – resilience and stability……………………….87 Chapter 6 Long-term indigenous soil and water conservation technology as survival strategy on steep mountains - an investigation of Chencha area, Southern Ethiopia..114 Chapter 7 Conclusions…......................................................................................................141 i Acknowledgements It is a pleasure and an honor to thank the people and institutions that made this study possible. First and foremost my sincerer gratitude goes to my supervisor Prof. Dr. Hans-Rudolf Bork for insightful guidance and supervision. I profited greatly from his two times field campaigns in my study area, southern Ethiopia. I value his scholarship, his friendship and his hospitality. Without him this work would never have come into being. I am also indebted to Prof. Dr. Rainer Duttmann , my second supervisor, for his suggestions and spending his valuable time on the evaluation of this study. I feel a deep sense of gratitude to my mentor Dr. Marie-Josée Nadeau for her unconditional support and great encouragement. I would like to thank your keen interest in me, my family and my work whenever met. My morale always went up after our discussions. I am honored to have you as my mentor. Special thanks to Prof. Dr. Johannes Müller for the lively discussions and experiences that we shared during our field campaign in Ethiopia. I appreciate your thoughtfulness and kindness. Dr. Mara Weinelt made we me to feel at home during my early year in kiel. Thanks for your kindness. I would also like to thank Helga Bork for her hospitality and considerate. My family and me enjoyed your invitations at your home. The visit to the different part of Schleswig- Holstein was also enjoyable and unforgettable. My family has very pleasant memories of their stay in Kiel, which we can never forget. Thank you. I am very glad to owe my indebtedness to the technical and administrative staff of the Graduate School of Human Development and Institute of Ecosystem Research and Geoarchaeology. Rhina Colunge is thanked for arranging administrative matters before and after my field work. You are most supportive and positive, always there when I needed. I thanked Florian Bauer, Key Adam and Peter Michelis for technical support. Many thanks also go to Sophia Dazert for soil lab analysis and Doris Kramer for drawing. I owe a big thank to Dr. Eileen Kücükkaraca and Mrs Caroline who edited the languages of the thesis. I appreciated your readiness to help. I am grateful to our secretaries Britta Witt and Kerrin Frahm for their kind assistances. I am also gratefully indebted to the staff of Leibniz Laboratory for the radiocarbon dating. I really enjoyed the hospitality and social events with the staff of the Leibniz lab which I will never forget. This research was funded by the German Research Foundation (DFG) under the auspices of German Excellence Initiative to the Graduate School of Human Development in Landscape (GSHDL). I have a great pleasure in acknowledging the financial support. Our GSHDL has become a real center of knowledge and excellence of interdisciplinary academic environment. My study benefited too much from the biweekly colloquiums, various courses workshops and i interactions among students. In the graduate School, several fellow PhD students shared time with me and made friends, thank you. I specially want to thank the Leibniz Laboratory for stipend scholarship for the last the phase of my study. I am very grateful. My final work would not have been possible without this funding. My gratitude also goes to Eskinder Solomon and Ato Chombe for the valuable supports and assistants during our field work. I would also like to thank Degelo Sendabo in the Ethiopian Mapping Authority for processing of seattleite images. I am indebted to Dr Iraj Emamoudin and Karina Penna for support and camaraderie. Several of my friends supported this efforts and I thank them. I am grateful for my friends in Addis Ababa Universtiy: Dr. Degefa Tollossa, Dr. Demis Zergaw, Shiferaw Muleta, Getachew for the support I have received from them. My friends Dr Tesfaye Shiferaw, Michael Tefera, Fekadu Adure, Tseahye Gebremedhine, Lumba, Zewdie, Aster, Samson (Mamush) deserve my sincere gratitude for morals and inspirations. I would also like to thank Ethiopian fellows in Kiel: Aynalem and her family, Dawit Gedamu and Hewan Teshome. My family has been marvelous. My late mother, Awa, had a dream to see my success to come true. My brother Wondu deserves special thanks for his endless interest and support throughout my all academic career. I am indebted to my mother in-law, Aynalem, for her unreserved support she gave to my family during my study. I am very much indebted to my sister Shure, Sisay, Bilen, Basliel and Abush for your constant support and encouragement during my study. I would also like to express my heartfelt thanks to my wife Mekdes Abraham who took all responsibilities to take care of our children. I thank you Mekdie for your patience and understandings during my study, field works travel and long night writings. My achievement is also yours. I owe special thanks to my children Neftalem, Shalom and Joseph who scarified their love during my absence. Above all I praise God. I will bless the LORD at all times; His praise shall continually be in my mouth. ii Summary Landscapes have undergone unprecedented changes in Chencha and Arbaminch areas, Southern Ethiopia, during the last century. Yet there exist well-established land-use systems and a wealth of local experience in maintaining and managing landscapes. The major objective of the study is to explore the dynamics of landscapes in a chronological and spatial order to identify trends, driving forces and impacts of land use systems, land cover and landscape structures during the last century in Chencha and Arbaminch areas. The methods used in the study include detailed field and lab investigations including C14 dating, satellite image interpretation, interviews and group discussions. The results of satellite image analysis (images from 1972, 1984 and 2006) show that cultivated land was expanded by 39 % from 1973 until 2006, but farming land per capita decreased enormously. In the same period of time, grassland as the main fodder resource for livestock shrank by 69 % – thus causing a huge decrease in livestock. Similarly, forest cover shows a 23 % decline from 1972 until 2006, with the most significant change from 1986 to 2006. Cultivated land scarcity and fragmentation can mostly be related to demographic pressure, which was exacerbated by government policy, the land tenure system, and the nature of subsistence agriculture. Changes were most intensive in the lowland; remarkable episodic forest changes also occurred, suggesting nonlinear spatial and temporal forest cover dynamics. According to farmers, the main driver for deforestation is agricultural land expansion, in response to local population increase and decline in agricultural production. Growing fuel wood demand, locally and in nearby towns, is another chief cause. Farmland scarcity has already caused farmers to cultivate marginal land areas and fragile ecosystems. This coupled with deforestation and cattle grazing in the remaining forestland, resulted in a decline in soil fertility and an increase in soil erosion by water. Gullying is one of the common and widespread processes of erosion in the area. Gully systems are characterized by the cyclic succession of phases of entrenchments with aggradations and with stability and soil formation. The extension of areas that are affected by gullying has increased dramatically over the last five decades. Gullies are highly modified and altered landscape elements, which in turn have immense implications on the environment and livelihood of the people. Gullies caused stripping of large amounts of soil from the highland and also water availability in the soil for plant growth is reduced. In addition, siltation of irrigation channels and weirs at the lowland is one serious obstacle for agriculture. The farmers, however, were resourceful and gathered a wide range of experience and developed skills over millennia to cope with the problems associated with population density and scarce resources. Despite the recent disruptions, they have used intensive cultivation systems, integrating crop-livestock practices and cultivated diversified