Introducing a glacier forefield monitoring site network to understand succession in the Northern Limestone Alps

Abstract

Since the end of the Little Ice Age (ca. 1855), glaciers retreated in the Alps, leaving new ground for genuine primary succession. The patterns and processes of glacier forefield succession have been studied globally for decades. Surprisingly, no such analysis exists from the Northern Limestone Alps. We therefore initiated a monitoring scheme with permanent plots to study plant succession and vegetation assembly at four forefields, namely the Hallstätter Glacier, Großer Gosau Glacier (both at Dachstein massif, Austria), Watzmann Glacier, and Blaueis (both at Berchtesgaden National Park, Germany), which is abbreviated as the BDGF (Berchtesgaden-Dachstein Glacier Forefield) platform. The aim of the long-term research envisaged and performed in this platform is to get a better understanding of the vegetation succession and community assembly in the glacier forefield development of the Northern Limestone Alps, using a multidisciplinary approach. Here, we introduce the basic characteristics of the BDGF platform; i.e. we describe the monitoring network, the observational design, and the methodological approaches. We present the baseline vegetation characteristics, and we outline the studies already initiated or to be performed in the near future. The methodology encompasses a chronosequence approach, where plots, using a frequency grid frame of 1 m × 1 m, are placed in specific successional stages (related to age classes since deglaciation). We show that, as expected, species richness and cover increase with age. Unexpectedly, though, these processes seem to be much slower than what has been observed in the Central Alps on siliceous substrates. We suggest that this could be due to the geological substrate, i.e. its chemistry as well as its karstic conditions, but also due to the morphology of the terrain, which hardly enables species colonization from above (i.e. following gravity) but mainly from below.