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Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

TABLE OF CONTENTS 1�

TABLE OF CONTENTS 1� GENERAL INTRODUCTION ......................................................................... 1� 1.1� Background and problem statement .................................................................. 1� 1.2� Objectives .......................................................................................................... 4� 1.3� Organization of the thesis .................................................................................. 4� 2� LITERATURE REVIEW .................................................................................. 5� 2.1� Conceptual framework of population growth and land degradation ................. 5� 2.2� Bio-physical conditions and economy of Ethiopia ............................................ 8� 2.3� Agriculture and its challenges in Ethiopia ......................................................... 9� 2.4� Land degradation and its implications ............................................................. 10� 2.5� Land-use/land-cover (LULC) change and its implications ............................. 12� 2.6� Vegetation cover change and its implications ................................................. 14� 2.7� Soil erosion and its consequences ................................................................... 16� 2.8� Practices and implications of soil and water conservation in Ethiopia ........... 17� 2.9� Land degradation and SWC practices in North and South Wello zones ......... 19� 3� STUDY AREA AND GENERAL METHODOLOGY .................................. 22� 3.1� Study area ........................................................................................................ 22� 3.1.1� Location.......................................................................................................... 22� 3.1.2� Bio-physical characteristics ............................................................................. 23� 3.1.3� Agriculture and farming system ...................................................................... 28� 3.1.4� Natural resource base and management .......................................................... 30� 3.1.5� Demography................................................................................................... 31� 3.2� General methodology ...................................................................................... 31� 4� LAND USE-LAND COVER AND NORMALIZED DIFFERENCE VEGETATION INDEX CHANGES IN WELLO .......................................... 35� 4.1� Introduction ..................................................................................................... 35� 4.2� Materials and methods ..................................................................................... 36� 4.2.1� Study area....................................................................................................... 36� 4.2.2� MODIS data acquisition and preparation ........................................................ 36� 4.2.3� Ground truth data collection and LULC type identification ........................... 38� 4.2.4� Digital elevation model ................................................................................... 39� 4.3� Results and discussion ..................................................................................... 40� 4.3.1� Implication of the topography on LULC change ............................................ 40� 4.3.2� LULC dynamics of Wello area ........................................................................ 41� 4.3.3� Spatio-temporal NDVI changes and implications for restoration ................... 47�

4.3.4� Possible drivers of LULC change in Wello ..................................................... 55� 4.4� Summary and conclusions ............................................................................... 58� 5� PERFORMANCE OF FARMLAND TERRACES IN SOIL FERTILITY MAINTENANCE ............................................................................................ 60� 5.1� Introduction ..................................................................................................... 60� 5.2� Material and methods ...................................................................................... 61� 5.2.1� Study area....................................................................................................... 61� 5.2.2� Sampling site selection and design .................................................................. 62� 5.2.3� Soil sampling, laboratory analysis and reference data .................................... 64� 5.2.4� Statistical data analysis .................................................................................... 66� 5.3� Results and discussion ..................................................................................... 66� 5.3.1� Biophysical changes after farmland terracing ................................................. 66� 5.3.2� Soil fertility variation on farmland terraces across the terrain ........................ 69� 5.3.3� Soil fertility variation at different positions within a terrace .......................... 76� 5.3.4� Soil fertility variation with age of farmland terraces ....................................... 79� 5.4� Summary and conclusions ............................................................................... 81� 6� PERFORMANCE OF FARMLAND TERRACES IN MAINTAINING CROP PRODUCTIVITY ............................................................................................ 84� 6.1� Introduction ..................................................................................................... 84� 6.2� Material and methods ...................................................................................... 85� 6.2.1� Study area....................................................................................................... 85� 6.2.2� Plot selection and sampling ............................................................................. 85� 6.2.3� Statistical data analysis .................................................................................... 88� 6.3� Results and discussion ..................................................................................... 89� 6.3.1� Impact of farmland terracing on crop yield across terrain .............................. 89� 6.3.2� Impact of farmland terracing on crop yield within a terrace ........................... 91� 6.3.3� Impact of terracing on crop yield across terrace age ....................................... 94� 6.4� Summary and conclusions ............................................................................... 98� 7� PERFORMANCE OF EXCLOSURE IN RESTORING SOIL FERTILITY 101� 7.1� Introduction ................................................................................................... 101� 7.2� Material and methods .................................................................................... 102� 7.2.1� Study area..................................................................................................... 102� 7.2.2� Sampling and analysis ................................................................................... 104� 7.3� Results and discussion ................................................................................... 108� 7.3.1� Changes in biophysical features of exclosures .............................................. 108� 7.3.2� Variation of soil fertility restoration across age of exclosures ...................... 112� 7.3.3� Exclosure soil fertility restoration variation across agro-ecological zones ... 115� 7.3.4� Exclosures soil fertility restoration variation across landscape ..................... 117� 7.4� Summary and conclusions ............................................................................. 118�