Ecology of silver fir (Abies alba Mill.) in the Bavarian Alps

Based on queries of the phytosociological databank BERGWALD, a compilation of 3.504 forest vegetation plots from the Bavarian Alps, the ecological niche of Abies alba is re-assessed. The tree species occurs mostly admixed in mountain forests with Fagus and Picea rather than forming distinctive communities of its own. Climatically, Abies is widely distributed to the upper limit of the montane belt, but occurs only sparsely in subalpine forest. Analysis of Ellenberg indicator values based on total species composition yielded the following results: As a tolerant species Abies regeneration has a marked preference for shady forest, which in turn Abies tree layers themselves help create. It also has a clear preference for acidic topsoil conditions. Sites with low N-supply, such as early successional stages on raw carbonate soils, are rarely colonised by Abies. Also, dry and markedly wet forest sites in the region are avoided by Abies. Permutation-based indicator species analysis found a large number of common forest species as being significantly associated with Abies and its frequent companion Fagus sylvatica, whereas there is a negative relationship with more specialised Seslerion and Erico-Pinion species. As Abies alba has very few specific companion species not shared with either Fagus or Picea, the delimitation of Abietetum-syntaxa appears mostly motivated by ecological rather than phytosociological considerations. As a result of its susceptibility towards game browsing, Abies regeneration is an indicator of high woody species richness. The study broadly confirms Abies alba's status as a climax species intermediate between Fagus and Picea, and demonstrates the potential of large phytosociological databanks for niche modelling