Welche Rolle spielt die endozoochore Ausbreitung von Pflanzen durch wildlebende Säugetiere? Untersuchungen in zwei brandenburgischen Waldgebieten

Abstract

HEINKEN, T.; HANSPACH, H.; SCHAUMANN, F.: How important is endozoochorous seed dispersal by wild mammals in centrat European forests?- Hercynia N.F. 34 (2001): 237-259. In two forest areas in Brandenburg (NE Germany) endozoochorous dispersal of plants by wild herbivorous and omnivorous mammals with a !arge home range was investigated. Feces of roe deer (Capreolus capreolus), fallow deer (Cervus dama), hare (Lepus europaeus) and wild boar (Sus scrofa) were collected throughout a vegetation period. Seeds from the feces collected each month were germinated in a greenhouse. The results were compared with the forest vegetation of both investigated areas. The mean contents of germinable seeds within the feces of herbivorous mammals were 20 to 40 times higher than those of wild boar, which apparently ingest only small amounts of seeds in their diet. Taking the population densities and defecation rates into consideration, it is evident that roe and fallow deer disperse high numbers of seeds, whereas wild boar and hare only carry small amounts. Altogether, 65 plant species were detected endozoochorously, 13 of these (among others Milium effusum, Moehringia trinervia and Ranunculus ficaria) for the first time. Due to their choice of diet, the spectrum of species dispersed by roe deer was smaller than the spectra of the other animals investigated. Though the investigated feces were collected within the forest areas, feces of roe deer contained no characteristic forest species, and only small amounts were detected in those of the other wild mammals. In the mesic forest habitat of the Brieselang, the herbivores dispersed almost exclusively annual species from ruderal vegetation, arable land and trampled areas. In the acidic forest habitat of the Krämer, they dispersed in particular species which occur both in oligotrophic grasslands and forests. In general, almost all diaspores dispersed by the herbivorous mammals were small ( <1mg), as they are less likely to be damaged during the chewing procedure. Wild boar also defecate live seeds of !arger diaspores, among them several cultivated plants. Several of the species dominating the acidic, and most dominating the mesic, forest stand are obviously dispersed endozoochorously either only very seldom or not at all by the investigated mammals. This is probably because their diaspores arenot able to survive the passage through the gut, due to their )arge size as weil as the fact that they are only produced in small numbers. The results confirm the assumption of low dispersal potentials of forest floor species and may be generally applied to centrat European forest habitats. Thus, at least by endozoochory, roe and fallow deer, hare and wild boar play only a small roJe in long-distance dispersal of forest species. Their importance may be greater in the dispersal of plant species of the open landscape.