Alpine summit vegetation and microclimate in the Nationalpark Berchtesgaden (GLORIA Germany – Northern Alps)

In recent decades, the rate of change in species richness in European mountain summits has increased and been correlated with rising temperatures. However, evidence of seasonal soil moisture deficit as a potentially emerging driver has rarely been discussed. Combined effects of warming and decreasing water availability will amplify climatic stresses on arctic-alpine biota. In fact, species richness changes have been strongest on calcareous bedrock, so that limestone mountain summits with their shallow soils might serve as early warning signals of species redistributions.

We present novel data on plant community dynamics from floristic summit monitoring in the European Limestone Alps - Nationalpark Berchtesgaden (DE-NPB, resurveyed 2007 - 2024, 2.203 - 2513 m asl) - along with in situ measured microclimate, soil temperature and soil moisture data. For details on species’ leading and trailing edges, we further draw on recently recorded field data from three different species pools, summit (GLORIA NPB), alpine (AlpVeg NPB), subalpine (Almenkartierung NPB).

Our data provide evidence of the summit vegetation species pool containing at least 185 plant species, thereby showing a significant increase of species richness over 2 decades. Generally, however, there is less increase in species richness in upper summit area sections than in lower summit area sections. Remarkably, the thermophilization Indicator D (S2025 – S2005) for the NP Berchtesgaden (0.038) is lower than the European Average D (0.054) (Gottfried et al. 2012), which would contradict the assumption of limestone Alps serving as early warning signals of species redistributions across the European Alps.

Florsitic summit monitoring in the Nationalpark Berchtesgaden