Little vegetation change during two decades in a dry grassland complex in the Biosphere Reserve Schorfheide-Chorin (NE Germany)

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Hüllbusch, Elisbabeth ; Brandt, L. Marie ; Ende, Paul ; Dengler, Jürgen:
Little vegetation change during two decades in a dry grassland complex in the Biosphere Reserve Schorfheide-Chorin (NE Germany).
In: Tuexenia. Bd. 36 (2016) . - S. 395-412.
ISSN 0722-494X

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Abstract

Semi-natural grasslands in many regions of Central Europe have experienced severe vegetation changes, e.g. compositional change and overall species loss, because of land use changes, atmospheric nitrogen input and also climate change. Here we analysed the vegetation change in a dry grassland complex (Gabower Hänge) in the Biosphere Reserve Schorfheide-Chorin (NE Brandenburg, Germany), one of the driest regions of the country. We resampled four 10-m² plots of each of four typical alliances (Festucion valesiacae, Koelerion glaucae, Armerion elongatae, Arrhenatherion elatioris) about 20 years after their original sampling with a relocation accuracy of approx. 10 m. The cover of vascular plants, bryophytes and lichens was recorded in both samplings. Overall compositional change was analysed with a detrended correpondent analysis (DCA). To interpret this change, we calculated unweighted mean Ellenberg indicator values for old and new plots. Furthermore we tested differences in constancy of individual species between old and new plots, as well as differences in species richness, cover of herb and cryptogam layer, ecological indicator values and unweighted proportion of species groups (vascular plants, bryophytes, lichens), floristic status (native or not), life forms, CSR-strategy types and Red List species. The results of the ordination indicated no significant vegetation change, but revealed tendencies towards more nutrient rich conditions. Ellenberg indicator values for nutrients and soil reaction were significantly correlated with the axes of the ordination. There were 28 species exclusively found in the new plots and 45 species of the old plots missing. While no species decreased significantly, there were seven species that increased significantly. Mean species richness was significantly increased in the new plots. There were no differences in mean Ellenberg indicator values. Proportions of vascular plants, neophytes, hemicryptophytes and CS-strategists decreased. We conclude that overall vegetation changes are small, indicating that the dry grassland complex at the Gabower Hänge are still in a good state and highly valuable for conservation. This relative stability over time compared to the situation in many other dry grasslands throughout temperate Europe is likely attributable to low nitrogen deposition and the dryness of the local climate. However, the detected tendency towards more nutrient-rich conditions should be taken into account in future management.