5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Study area and general

Study area and general methodology Performance of exclosure in restoring soil fertility The study was conducted in Gubalafto Wereda (district) considering exclosures of two different ages (10- and 27-year-old) and control (open grazing marginal land) located in two age-categorical zones (Daga/cool and Weyna-Daga/mild) at three landscape positions (lower, middle and upper) (Chapter 7). The identification of exclosures and control sites was done through intensive reconnaissance survey followed by sampling during the main survey. Soil samples were collected from each exclosure and control sites and analyzed for major soil properties. The soil analysis data were statistically tested using a general linear model. Synthesizing implications of SWC measures for land rehabilitation The results of the above four independent analyses were synthesized and the cumulative effects of land rehabilitation/restoration examined for the entire study area (Chapter 8). In this part, the LULC and NDVI change, crop yield and soil fertility change due to SWC interventions, mainly farmland terracing and exclosure, were evaluated in respect to land restoration. Based on the synthesis, concluding recommendations are given (Chapter 9). 34

Land use-land cover and normalized difference vegetation index changes in Wello 4 LAND USE-LAND COVER AND NORMALIZED DIFFERENCE VEGETATION INDEX CHANGES IN WELLO 4.1 Introduction The forest cover of the country in the early 1900´s was estimated about 40%. However, this was destroyed within half a century, i.e., the forest cover declined to 16% in the 1950´s and to 7% in the 1960´s (Pohjonen and Pukkala 1990; EFAP 1994; FAO 2001). Deforestation continued, and in 1980´s the forest cover had dropped to below 3% (Pohjonen and Pukkala 1990). Expansion of agricultural land at the expense of forest and natural vegetation, demand for household energy, forest fires due to extended dry periods and demand for timber and non-timber products were cited as leading causes of the forest cover deterioration (Pohjonen and Pukkala 1990; FAO 2001; Feoli et al. 2002). Among other factors, demand for cultivable and grazing land accounts for the larger share of the deforestation (Tefera et al. 2002; Asefa et al. 2003). This land useland cover (LULC) change threatens the environment, resulting in accelerated soil erosion, habitat and biodiversity loss, micro-climatic change, and overall decline in the productivity of land (Badege 2001; Tefera et al. 2002; Asefa et al. 2003; Amsalu et al. 2007). Intensified rehabilitation programs to reverse land degradation due to LULC change were widely launched after the 1984/85 drought (Badege 2001; Nyssen et al. 2004). Since then, various activities such as tree plantations at homesteads and in woodlots, reforestation and enclosure of degraded lands for self-regeneration (exclosure) have been carried out in most highland areas with special emphasis on drought-prone parts (Badege 2001; Mekuria et al. 2007). However, tree plantations are dominated by Eucalyptus species, while the cover of indigenous species continues to shrink (Pohjonen and Pukkala 1990). Though rehabilitation interventions showed improvements, the extent of those interventions did not offset the rate of conversion (Mekonnen and Bluffstone 2008). There are, however, no adequate studies that evaluate the performance of the various interventions, and some of the reports are not consistent. For example, FAO (2001) reported a 4.2% forest cover, while recently media has been broadcasting that the forest cover has increased to 11%. The LULC change is clearly visible in degradation-prone areas of the northern highlands. Wello is one of the areas where natural resource rehabilitation interventions 35

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