Vegetation dynamics in the natural forest reserve Geißberg – Results of a 20 year vegetation – monitoring

281-286

Artikel aus einem Buch

200210758

Protected Areas facing the Biodiversity Crisis: Conference Volume to the 7th International Symposium for Research in Protected Areas (2022) , 281-286

The main aim of the Austrian Natural Forest Reserve Programme is not only to protect selected forests from silvicultural harvest and management but to enable natural processes in different forest ecosystems. In the natural forest reserve (NFR) Geißberg, we document this development with a vegetationmonitoring. The NFR is situated in the Vienna woods and is dominated by thermophilous beech forests. Several different tree species are admixed. Some of them, in particular Austrian black pine are remnants of the former silvicultural management. In 1995 27 clusters of monitoring plots, each 8 x 1m², were installed and permanently marked. These plot-clusters are embedded in 500m² plots for the documentation of the tree layer. Every five years all occurring vascular plants were recorded and their cover estimated on the 216 (27x8) 1m2-plots . Until now the survey was repeated five times revealing distinct changes in the herbal layer. In the course of twenty years a significant and continuous decrease in vegetation cover from 39.7% in 1995 to 9.9% in 2018 could be detected. Simultaneously, the number of vascular plant species per m² halved in the same time span from 9 (median) to 4.5 species. An analysis with Ellenberg indicatorvalues shows that the highest losses of species occur in the group of species which has high demands
regarding light . Several of these species are adapted to nutrient-poor conditions as well. Considering their phytosociological affiliation, we can observe a shift of the plant community from light flooded stands to more dense conditions with higher shares of beech.
Keywords: Natural Forest Reserve, vegetation monitoring, Vienna Woods, vegetation dynamics.