5 years ago

Die Wirksamkeit von Boden

Die Wirksamkeit von Boden

Overall summary and

Overall summary and conclusions 9 OVERALL SUMMARY AND CONCLUSIONS 9.1 General summary The economy of Ethiopia largely depends on agriculture. However, the sector has been constrained by land degradation. In response to the land degradation, the government has been taking policy actions and implementing soil and water conservation measures (SWC) since the 1980´s. The conservation practices include both mechanical and biological measures on farmlands and degraded marginal communal lands. The main structures on farmland are terracing, while degraded marginal communal lands have been protected from human and animal interferences through exclosure and the terrain modified by constructing mechanical structures. In order to understand the impact of the SWC measures, particularly exclosure and farmland terracing, a study was conducted in North and South Wello zones of the Amhara National Regional State, Ethiopia. The study area is located between 10°12� and 12°22� north latitude and 38°30� and 40°14� east longitude. The study evaluated exclosure in soil fertility and vegetation restoration using soil samples and satellite data. The satellite data were used to analyze landuse/land-cover (LULC) and normalized differenced vegetation index (NDVI) change as an indicator of vegetation degradation and/or restoration. The study also evaluated the impact of farmland terracing on soil fertility and crop yield, and their spatio-temporal variability. Finally, a synthesis of the analysis results was conducted with respect to land restoration. The results of the analysis show a positive impact of the measures (exclosure and farmland terracing) in maintaining and/or restoring soil fertility, crop yield and vegetation cover. The LULC- and NDVI-change analysis covered the North and South Wello zones over an area of 300,000 km 2 . It applied a remote sensing approach, which used moderate resolution imaging spectrometer (MODIS) surface reflectance image and NDVI data composited at 8-day and 2-monthly intervals, respectively, between 2000 and 2010. The images were classified using supervised classification, and the NDVI data analyzed for spatio-temporal changes. The analysis showed remarkable changes, mainly improvement in grassland/woody grassland (increased by 14.6%) and in degraded woody vegetation (decreased by 13%). Similarly, the area covered by NDVI value >0.4 and 0.3 to 0.4 increased by 12.5% and 2.3%, respectively. The analysis also 132

Overall summary and conclusions showed an increase of the NDVI value in the central parts of the study area, particularly along the highways, which indicates restoration. Conversely, remote parts were identified as degradation hotspots, i.e., NDVI decrease. On the other hand, comparison of the digital elevation model and the NDVI change analysis indicates that larger parts of the steep landscapes show vegetation restoration despite the continuing population growth. Thus, this change can be attributed to government policy. Policy implementation could be influenced by community awareness level, and activity of local stockholders such as local administration (village/Kebele and district/Wereda) and involvement of non-government organizations (NGOs). The role of exclosure on natural resource restoration was studied not only in the LULC- and NDVI-change analysis but also regarding the impact on soil fertility restoration. Accordingly, the performance of exclosure in the soil fertility restoration evaluation at micro-watershed level was done in the Gubalafto Wereda (district) of the North Wello zone. The analysis used soil samples collected from exclosures (10- and 27-year-old), and control sites (open lands) in three landscape positions (upper, middle and lower) in the Weyna-Dega (mild) and Dega (cool) agro-ecological zones. Soil samples were collected from 20 m 2 plots at 1-m intervals along the sides and diagonals of the plots to 15 cm depth and composited. The composite samples were analyzed in the laboratory for selected physico-chemical properties using standard methods, and the data statistically tested using analysis of variance (ANOVA) in a general linear model (univariate) in SPSS 17. The analysis revealed significant soil fertility improvement. Soils of the exclosures had significantly higher organic carbon (OC) and total nitrogen (TN) contents than the open sites. However, the differences decreased with increase in age. Soils of the 10- and 27-year-old exclosures had significantly higher OC and TN contents than those on open sites, while insignificant differences were observed between exclosures. The OC and TN content differences between the control sites and the 10year-old exclosures were 41% (6.7 g/kg) and 44% (0.7 g/kg), respectively, while differences between the 10- and 27-year-old exclosures were only 9% (2.1 g/kg) and 22% (0.5 g/kg), respectively, which indicates that the restoration rate reached a steady state with time. The soil fertility restoration also significantly varied with agroecological zone. Exclosures in the Weyna-Dega zone had significantly higher soil fertility restoration than those in the Dega zone. This could be attributed to the effect of 133

Voluntary and incentives programmes for soil ... - Unser Boden
Für die Wand Für den Boden Auf Tisch und Theke On the wall ... - Helit
Austrian agri-environmental program - Unser Boden
Die ökologische Bedeutung von Samenbanken, Keimung und ...