5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

General introduction 1.2

General introduction 1.2 Objectives The general objective of this study is to analyze the effectiveness of soil and water conservation measures for land restoration in the Wello area, northern Ethiopian highlands. The specific objectives of the study are: � To analyze the changes in the land use/cover (LULC) and the normalized difference vegetation index (NDVI) in the North and South Wello zones of Ethiopia with the view to assessing vegetation restoration and degradation hotspots; � To evaluate the performance of farmland terracing in soil fertility and crop yields maintenance and/or improvement in the Maybar watershed, South Wello Zone, Ethiopia; � To evaluate the performance of exclosure in restoring soil fertility in Gubalafto district (Wereda) of North Wello zone, Ethiopia; � To assess and conduct a synthesis of the implications of SWC measures on land restoration in the North and South Wello zones. 1.3 Organization of the thesis The thesis is structured in nine chapters. The general introduction, which includes background information, problem statements and research objective, is given in Chapter 1. A literature review and description of the study area including general methodology are given in Chapter 2 and 3, respectively. The analyses are covered in Chapter 4 to Chapter 9. The LULC and NDVI change detection assessing the dynamics with respect to land restoration particularly by exclosure is given in Chapter 4. The impacts of farmland terracing on soil fertility and crop yield are given in Chapter 5 and 6, respectively. The role of exclosure on soil fertility restoration is given in Chapter 7. A synthesis of the implications of SWC measures for restoring degraded land is presented in Chapter 8. Overall summary and conclusions are given in Chapter 9. 4

2 LITERATURE REVIEW Literature review 2.1 Conceptual framework of population growth and land degradation Water, land and other natural resources are the basis for humans to generate income and produce consumable goods and services (Wallace 2007). Nevertheless, their availability is limited in space and time, and this influences livelihoods, especially of the rural poor who directly depend on them (Antoci et al. 2009). The population density of the developing countries is already higher than the agricultural production of the arable land, which leads to natural resource misuse (Cuffaro 1997). Therefore, population growth, resource management and degradation are central elements for sustainable ecosystem functioning. Conversely, resource deterioration cumulatively leads to environmental and land degradation (Cuffaro 1997; Antoci et al. 2009). There is no agreed theory that adequately addresses the relationship between population growth, resource management and land degradation. The scope and concept of resource management and land degradation are broad and multi-dimensional. Sustainable resources use could determine management practices and priority setting in the processes to fulfill human interests in a given time. The managers also have different perspectives that could ultimately lead to degradation. For example, soil is perceived and used differently by different managers unless a common management plan is designed. This can be illustrated by the management of soils in a quarry. In the absence of a comprehensive plan concerning sustainable use of the quarry and the topsoil, the use of one could degrade the other (Khater et al. 2003). Hence, planning should consider sustainable use without neglecting the possible potentials. Resources can also be misused by land managers opting for advantages, while a certain practice can result in unintended consequences, e.g., the soil burning (Guie) practice in some areas of the Ethiopian highlands. The purpose is to reduce weed infestation and to increase crop yield. However, the practice lead to depletion of soil nutrients such as nitrogen, organic carbon and associated exchangeable bases, and increases soil vulnerability to erosion (Koch and Pülschen 1990). In Sub-Saharan African (SSA) countries, encroachment on marginal lands due to livestock grazing and cultivation used to be regarded as a means to solve land shortage problems in order to fulfill the basic needs of the growing population (Nana- 5

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