Natürliche und anthropogene Veränderungen von Vegetation und Relief in den Zentralalpen im Spätglazial und Holozän.

Eine Fallstudie aus dem Südtiroler Schnalstal

Abstract

The area of investigation is situated in the upper Schnalstal, a side valley of the Vinschgau, at an altitude of 1894 m a.s.l. The actual vegetation of this central alpine region is subalpine woodland composed of larches. Pollen analyses and sediment stratigraphy of a tilted fen show the Late-Glacial and Holocene vegetation history. The results on the whole correspond with the Central Eastern Alps. The earliest sediments developed during Late-Glacial Allerød. At this stage sparse larch wood already existed. The Holocene shows forests composed of larch, pine and spruce - a development widely spread within the Central Eastern Alps. Yet during late-Atlantic - increasing during sub-Boreal and sub-Atlantic - human influence is obvious. Deforestation by fires and establishment of pastures alternate with reforestation. During sub-Atlantic, the pioneer tree species larch gains habitat by the clearing of spruce; this is reflected until today by the pure larch forests of Schnalstal. The assumption expressed in the literature, that the climate of the region would be too dry for the spruce, may therefore be rejected. Pollen analyses and radiocarbon datings of an adjacent fen are contradictory. This problem may be solved by archive material which shows a fish pond of the Late Middle Ages. The pond is in a natural depression and is accumulated by a man-made dam. In this depression, minerogenic sediments accumulated by a debris flow channel during the modern age. After the filling of the depression the fen vegetation settled. Besides the profound change of mountain forests from late-Atlantic, this study also shows the local change of the relief by human influences.