CHARACTERIZING THE INITIAL STAGE OF PROGLACIAL SOIL FORMATION ALONG NINE SHORT POSTGLACIAL CHRONOSEQUENCES DISTRIBUTED BETWEEN THE FRENCH AND SWISS ALPS AND THE PERUVIAN ANDES

In deglaciating terrains, the formation of new soil after the retreat of the ice is the result of long-term consequences of climate change and might provide insights for future environmental scenarios. However, little is known about proglacial pedogenesis processes. The recently deglaciated terrains (<150 yrs.) are subject to weathering and pedogenesis, and freshly exposed sediments are prone to react highly with the environment. Fine mineral deposition and transformation mechanisms are the early steps of soil formation, and scientific studies need to establish these boundary conditions to understand the patterns of soil forming processes. In addition, during the first decades of soil genesis the variability observed might rely on both the geomorphic activity and the occurrence of pioneer vascular species. As well, the initial processes of soil formation and input of nutrients rely on the activity of microorganisms and on the emergence of a biological soil crust, both controlled by soil humidity and temperature. Here, we study soil properties (pH, texture, bulk density, water and organic matter content, and temperature) and geomorphic dynamics of nine proglacial landscapes distributed between the Alps (France and Switzerland) and the Peruvian Andes and their interactions with alpine biodiversity. The proglacial areas offer a chronosequence from 0 to 150-year-old surfaces. We use geochemistry, geomorphology, and observational data (soil temperature) to characterize the properties of proglacial soils and the drivers of their formation building connection between proglacial soil and vegetation development. Through our preliminary results we expect an accumulation of organic matter within the chronosequences and a decrease in grain size revealing physical weathering processes. In addition, we expect to encounter considerable differences between sites as the result of geology, geomorphology, and local biodiversity.