The influence of climate and vegetation on the water balance of montane and alpine ecosystems

This thesis aims to quantify effects of land use on evapotranspiration (ET) and the hydrology of mountain watersheds (the Ursern valley, Central Switzerland). The first chapter investigates interactions between vegetation structure (leaf area) and climate and the way that these affect ET along a montane - alpine elevation gradient. The two other chapters address related, applied questions and explore the way that current changes in land use influence ET and with this, catchment runoff and hydro-electric potential. During the past few decades, abandonment has caused widespread tall grass sward growth and later, the establishment of Alnus shrubs. We quantify changes in ET and show that abandonment and shrub establishment lead to increased ET and hence reduce catchment runoff. We quantify the economic value of continued sustainable land care and conclude that use of the landscape by farmers not only enhances biodiversity values but also revenues from hydro-power stations.