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5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Land use-land cover and

Land use-land cover and normalized difference vegetation index changes in Wello Note: Land-use/land-cover, i.e., A = cultivated and others, B = forest, C = degraded woody vegetation, D = grassland/woody grassland and E = water bodies Figure 4.4 Land use/land cover dynamics of Wello The analysis indicates that the area covered by grassland/woody grassland increased by 14.4% from 2000 to 2009 (Figure 4.4) due to the effort to restore degraded lands. Although grassland and woody grassland were aggregated together in one LULC mapping unit, they occupy different topographic setups. Most grassland occupies lowlying areas that have drainage problems as they are prone to water-logging during rainy seasons. This makes these lands unsuitable for other uses like cultivation, so they have remained as pasture for centuries. Conversely, woody grasslands are mostly recent exclosures that occupy steep landscapes (mainly over 30% slopes). This indicates that the major change on grassland/woody grassland is mainly due to recent exclosure. The area mapped as grassland/woody grassland on steep slopes has undergone various changes. These areas originally had a forest cover before clearance. The current restoration measures (exclosure) have led to regeneration of the forest. Observation of exclosures of different age indicates that woody grasslands will develop to forest or bush land through time as the lower-order vegetation is replaced by higher order. Similar vegetation dynamics with age of exclosure were reported by different studies (Carla et al. 2003; Descheemaerker et al. 2006; Zhao et al. 2010; Mekuria et al. 2011). According to the 2009 image, the area covered by forest and grasslands/woody grassland accounts for 34.5%, where the area above 30% slope accounts for 40% of the 46

Land use-land cover and normalized difference vegetation index changes in Wello total area. Grassland/woody grassland in 2000 accounted for 10.8%, which indicates that the area of grasslands located on slopes