Proglacial pedogenesis along nine short postglacial chronosequences in the French and Swiss Alps and the Peruvian Andes

Keywords: Pedogenesis, Anthropocene, CLORPT, Chronosequences, Soil Organic Matter, Proglacial soil
Session Type: Virtual Poster Abstract
Day: Friday
Session Start / End Time: 2/25/2022 03:40 PM (Eastern Time (US & Canada)) - 2/25/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 49

Abstract

The formation of new soils after glacier retreat due to climate change can provide insights into the rates of soil formation during the Anthropocene. Recently deglaciated terrains (<150 years) are subject to weathering and pedogenesis, freshly exposed sediments are prone to react readily with the environment. During the first decades of soil genesis, the variability observed relies on the typical CLORPT factors, but geomorphic activity and climate change are rapid and biotic migrations are highly variable. This paper studies the soil properties, composition, geomorphic dynamics, and environmental characteristics of nine chronosequences of deglaciation in the Alps and the Peruvian Andes. Between 2019 and 2020 we collected 189 soil samples within the nine proglacial landscapes and buried 113 temperature sensors. We measured soil organic matter (SOM), nitrogen and carbon content, pH, elemental composition (Si, Fe, Al, K, Ca, S, etc.), texture, and bulk density. Our preliminary results show faster SOM accumulation in the Andean proglacial soils than within the Alps. Similarly, higher N and C accumulation are detected in the Andean soils at a similar age. In most sites, we observe a decrease in pH values along the chronosequences due to the formation of organic matter acids and to the dissolution and leaching of the carbonate. Finally, at first glance, the elemental composition of the Andean and Alpine samples does not differ substantially, which suggests that proglacial soil formation is mainly driven by climate characteristics and we can associate faster soil formation with subtropical climates.