Abstract ID: 3.9698 | Accepted as Poster | Poster | TBA | TBA

During the last decades shrub encroachment occurred across arctic and alpine environments. Especially in the European Alps decreasing grazing pressure, land abandonment, and climate warming favour the expansion of green alder [Alnus alnobetula (Ehrh.) K. Koch; former Alnus viridis (Chaix) DC.] and Pine tree [Pinus mugo (Turra)]. Expansion of A. alnobetula primarily occurs in avalanche gullies and steep north-facing slopes with high water availability. On the other hand, A. alnobetula is also expanding into sun exposed sites with shallow soils and impaired water availability. Which typically are colonized by P. mugo. Nevertheless, shrub encroachment may strongly affect ecosystem biogeochemical cyclers such as transpiration, and runoff. Therefore, the specific goal of this study was to investigate seasonal patterns of sap flow density of A. alnobetula and P, mugo at four study plots within the treeline ecotone on Mt. Patscherkofel (1950 – 2200 m a.s.l.). These data were then scaled up to the stand level per growing season and compared with published transpiration rates of adjacent low stature vegetation and tree canopies. Our estimates suggest shrub encroachment may considerably affect the water balance of the treeline ecotone. This study was funded b the AUSTRIA Science Fund (FWF), P 34706-B).