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5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Performance of exclosure

Performance of exclosure in restoring soil fertility d) Ayda-Tig exclosure (mild, 27 years old) c) Lenche-Dima exclosure (mild, 10 years old) b) Abo-Dur exclosure (cool, 27 years old) a) Zendo-Girat exclosure (cool, 10 years old) e) Open area (mild) f) Open area (cool) Figure 7.5 Different-aged exclosures and control sites in cool and mild agroecological zones in Gubalafto district The results of the present study reveal typical vegetation types in the two agroecological zones. For example, Acacia asak, Carissa edulis, Cupressus lusitanica, Erica arborea, Eucalyptus globulus, Euphorbia abyssinica, Hagenia abyssinica, and 110

Performance of exclosure in restoring soil fertility Juniperus procera were typical species in the cool zone exclosure while Acacia saligna, Acacia seyal, Aloe ferox, Eucalyptus camaldulensis, and Euclea schimperi were typical in the mild zone. The tree types identified as typical for the cool and mild zones are similar to those in the classifications by Bekele-Tesemma et al. (1993). Other studies also reported that differences in climatic and environmental conditions were attributed to vegetation cover, and structure variation (Descheemaeker et al. 2006; Mekuria et al. 2011). The vegetation also showed differences in cover, where the cool zone tended to have a higher cover than the mild zone (Table 7.1). The difference in vegetation types in the two zones could play a significant role in determining the soil restoration rate. The biophysical conditions of the exclosures did not show differences due to slope change. The study area is densely populated (Chapter 3). Consequently, people live and carry out agricultural activities near marginal lands. Particularly the lower boundaries of exclosures are close to settlement areas, grazing and cultivated lands, which could results in occasional disturbances. During the field survey, it was observed that exclosures had SWC structures such as hillside terraces, micro-basins, cut-off drains and trenches (Table 7.2, Figure 7.6). As per the district agriculture office and community information, the SWC structures were constructed before implementation of the exclosures. The purpose of SWC structures is in-situ soil and water conservation. From our observations, management level and the SWC constructions play a more important role regarding the vegetation cover in the exclosures than slope difference. Figure 7.6 Physical SWC structures constructed before exclosure 111