ESJ57 シンポジウム S18-9
*M. Schuetz, A. C. Risch （Swiss Federal Institute for Forest, Snow and Landscape Research）
Animals are important vectors for the dispersal of seeds within and between ecosystems. They thereby alter seed bank and consequently vegetation dynamics at various spatial scales. We studied how two different sized animals inhabiting the same grassland ecosystem in the Swiss Alps, affect these dynamics: the mound building narrow-headed ant (F. exsecta Nyl.) and red deer (Cervus elaphus L.).
Recently, we counted roughly 1200 active ant mounds on the grassland and up to 40 deer that visited the grassland during the night. Both animal species show a distinct spatial pattern with most mounds located in areas that are rarely visited by red deer and vice versa.
We found different seed dispersal patterns by the two species with ants dispersing more seeds than deer. However, deer were found to disperse the seeds evenly across the grassland, while ant activity lead to a clumped seed occurrence close to the forest. Seeds from graminoids dominated in ant mounds in contrast to deer dung where herbs were predominant. At a small spatial scale graminoids were found to dominate in the vegetation around ant mounds. At a larger scale graminoids were dominant in areas with high ant while herbs dominated in areas with high deer activity.
Overall, both species play a considerable role in the grassland ecosystem studied.