The alpine treeline under changing land use and changing climate: Approach and preliminary results from continental Norway

Abstract

This study aims at improving the comprehension of the alpine treeline, partly as a means of projecting landscape evolution in an anticipated warmer future. The main problem to be solved is to distinguish effects and responses of climate change and human impact, two driving forces which have both caused an increase in the altitude of the alpine treeline over the past century. Thus, an interdisciplinary approach has been transposed to the Norwegian mountains, combining socio-geographical, landscape ecological and adjusted dendroecological methods. Preliminary results presented for the continental Norwegian mountain region Vågå, Oppland, prove the treeline to be in a regeneration stage after a period of major human forced depression. Climatic conditions at the treeline and growth rates of birches indicate that the treeline is not at its distribution limit. Consistent grazing pressure and dense vegetation cover is the most likely explanation.