Plant Succession in Glacier Forelands Controlled by Site Age Alone?—A Case Study at Schwarzenbergferner, Stubai Alps, Tyrol, Austria

Glacier forelands are well-suited for investigating vegetation development and plant colonization dynamics in previously uninhabited areas. The areas exposed by retreating glaciers represent sites without seed banks; thus, plant colonization almost always represents a true primary succession. Vegetation dynamics relies on diaspores brought in from the surrounding. A common approach for studying long-term vegetation developments is the employment of so-called chronosequences, deriving temporal sequences from spatially different sites of various site ages. In glacier forelands, datable traces of former glacier extents are generally used for site age estimation. In 2009 and 2010, vegetation sampling for ten points in time since deglaciation was carried out in the foreland of Schwarzenbergferner, Ötz valley, Austria. The study area extends between the recent glacier terminus and the terminal moraine left by the Little Ice Age glacier during the maximum extent (around 1850). The vegetation survey is supplemented by a one-year long measurement of soil temperature (1 September 2010–31 August 2011), which allows not only for an assessment of the seasonal course of the topsoil thermal conditions across the chronosequence, but also for the determination of the snow cover duration and the length of the vegetation period. This article summarizes the vegetation development and microclimatic conditions along the chronosequence and discusses the results, considering the interplay between the time since deglaciation and elevation being a microclimatological proxy.