Ecological rehabilitation of degraded hill slopes in southern Wello, Ethiopia

Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

Sammanfattning: Clearing of vegetation has left large areas of southern Wello (Ethiopia) at a high risk ofland degradation. In this study, the causes, extent and consequences of land degradationproblems are reviewed. To see land cover changes, aerial photographs from 1958 and1986 were compared with the help of a GIS procedure. By applying multivariateclassification and ordination techniques on the vegetation and environmental datacollected from 65 plots (20x20 m big), the vegetation of the study area was analyzed.Possibilities of ecological rehabilitation were assessed by analyzing results from a soilseed banks experiment and from the study of vegetation dynamics in permanent plots.The land cover changes interpreted from the aerial photographs indicated adeterioration of forests, shrublands and riverine vegetation into open areas andsettlements. This deterioration was manifested in the present vegetation types whichincluded forests, woodlands, shrublands, grasslands, degraded and regenerating sites.The soil seed banks are dominated by herbs with very few tree and shrub seedlings.A low floristic similarity (Sørensen index 26%) was observed between the seed banksand the standing vegetation. Nevertheless, the seed banks' contribution to initial plantcover can not be underestimated.In the permanent plots, an increase in number of individuals and intercept lengthswas recorded. Moreover, there was a strong correlation (r = 0.77) between the interceptlength of the tree/shrub layer and the position of plots on CA - axis 1 of the field layer.Ecological rehabilitation of degraded areas in southern Wello will be successful ifthe goals are geared towards sustainable use of the hill slopes rather than focusing onrecovery of the original vegetation. Measures taken in this line can be helpful inwinning the confidence of the local people without whose participation much can not beaccomplished.

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