Reconstruction Of Environmental And Vegetation Changes On The Sanetti Plateau In South Ethiopia Since The Last Deglaciation Based On Biogeochemical Analyses Of Sediments

The aim of the study was to contribute to a better understanding of the environmentalrnand vegetation changes of Erica arborea and Erica trimera at the Sanetti plateaurncommunity, in the upper Afroalpine vegetation zone of the BMNP (Bale Mountain NationalrnPark) South Ethiopia. A sediment core was recovered from a small glacial depression at 3990mrnaltitude in the Bale Mountains of Ethiopia. Accumulation δ13C and δ15N values of the soilrnorganic matter (SOM) in the sediments were analyzed with the objective to get information aboutrnenvironmental changes. The results support hypotheses about climate influences or vegetationrnchanges onδ13C values of SOM during the late Glacial and Holocene δ15N values showed arnnegative trend with increasing sediment depth, indicating that after deglaciation N cycles werernvery closed but opened with pronounced fluctuations towards the beginning of the Holocene.rnδ15N maxima during the Late Glacial and Early Holocene roughly correlate with BCrnmaxima supporting the hypothesis that also fire might influence δ15N values of SOM. Ifrndifferences in land use history have larger effects on δ13C values than climate fluctuations thenrnδ15N values of SOM may be valuable in conjunction with δ13C analyses for reconstructingrnaspects of land use and climate variability. Erica shrub and forest decreased in area withrnincreasing altitude and the Afroalpine ecosystem expanded on the plateau. Human impact on thernhigh-altitude Afroalpine and Ericaceous vegetation has been relatively minor, confirming thatrnthe endemic biodiversity of the Ethiopian mountains is an inheritance of natural Holocenernvegetation change. The aim was to test the potential of Black carbon (BC) analysis in order tornmake clear the input from grass and wood fires and discuss the potential limitations of thernmethod on sediments of the Garba Guracha. Sediments cover the cultural transition from hunterrngatherers to food-producing communities during middle of Holocene.rnKey words; Bale Mts., Sanetti Plateau, Erica shrubs, fire history, stable isotope (δ13C, δ15N) andrnBC

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