5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Implications of soil and

Implications of soil and water conservation measures for land rehabilitation- a synthesis critically reduced during dry periods, considerably increased the base flow. Strong flash flooding from degraded lands was also reduced due to the mechanical structures and vegetation recovery. The structures intercepted runoff, and eroded soils and soil fertility in the exclosures also improved significantly (Chapter 7). Soil nutrient loss after farmland terracing was also considerably reduced (Chapter 5). As a result, crop yield on terraced farmland showed relatively stable conditions (Chapter 6). The effect of SWC on the restoration and rehabilitation of degraded lands is demonstrated by the conceptual framework given below (Figure 8.2). Figure 8.2 Conceptual framework demonstrating role of SWC measures in degraded land restoration 8.4 Short- and long-term implications of exclosures Natural resource conservation planning failures could threaten sustainability and lead to complete rejection of the measures by the local community. Therefore, conservation 124

Implications of soil and water conservation measures for land rehabilitation- a synthesis interventions should critically consider the short- and long-term benefits and their implications. The benefits and shortcomings should be identified so that appropriate corrective measures can be taken at an appropriate stage. The current analysis shows that exclosures resulted in significant vegetation and soil fertility restoration (Chapter 7). Soils of the exclosures showed remarkable improvements in physico-chemical properties, particularly significant in the case of OC and TN restoration. The soil fertility restoration was mainly due to the impact of exclosures, which led to improve OM addition and mineralization. However, restoration showed spatial and temporal variability. Although soil fertility restoration varies with age, the rate tends to decrease with exclosure age, and this is in line with other studies (Asefa et al. 2003; Carla et al. 2003; Fu et al. 2003). Self-restoration of degraded land through exclosure also showed species and cover dynamics; where the changes were from the lower to higher vegetation layer and order (Mekuria et al. 2011). SWC structures implemented at the beginning of exclosures also enhanced in-situ conservation. Consequently, as opposed to the common phenomena, a non-significant soil fertility gradient was observed across the terrain (Chapter 7). Moreover, exclosures had a positive impact downstream such as reducing flood hazards at lower terrain positions, decreasing farmland encroachment by gully and riverbank erosion, and improving the overall hydrology (Chapter 4). The highlands in general and the study area in particular are densely populated and have a high livestock density, i.e., the study area with an average 76 TLU´s km -2 livestock and 134 persons km -2 . The area is also characterized by rugged topography, where steeper slope areas account for 40%. Moreover, about 90% of the population lives in rural areas where the economy entirely depends on agriculture (Chapter 3). These factors indicate competition for resources, thus the area needs careful land-use planning and management. The LULC changes, particularly conversion of marginal lands, originally covered by natural vegetation, to grazing and cultivation were due to population pressure (Chapter 4). The LULC analysis also revealed that less sloping lands with deeper soils are used for cultivation and settlements. Lands with slopes

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