Decoding potential effects of climate and vegetation change on mineral weathering in alpine soils: An experimental study in the Wind River Range (Wyoming, USA)

• Main Authors: Mavris, Christian, Furrer, Gerhard, Dahms, Dennis, Anderson, Suzanne P, Blum, Alex, Goetze, Jens, Wells, Aaron, Egli, Markus
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2015
• Subjects: Institute of Geography; 910 Geography & travel; Wind River; Tundra
• Online Access: https://www.zora.uzh.ch/id/eprint/120428/; https://www.zora.uzh.ch/id/eprint/120428/1/2015_Egli_1-s2.0-S0016706115001287-main.pdf; https://www.zora.uzh.ch/id/eprint/120428/2/2015_Geoderma_Mavris_et%20al_2015.pdf; https://doi.org/10.5167/uzh-120428; https://doi.org/10.1016/j.geoderma.2015.04.014

Climate change and a related increase in temperature, particularly in alpine areas, force both flora and fauna to adapt to the new conditions. These changes should in turn affect soil formation processes. The aim of this study was to identify possible consequences for soils in a dry-alpine region with respect to weathering of primary minerals and leaching of elements under expected vegetation and climate changes. To achieve this, a field empirical approach investigating an altitudinal sequence was used in combination with laboratory weathering experiments simulating several scenarios. The study sites are located in Sinks Canyon and Stough Basin of the Wind River Range, Wyoming, USA. The following sites (from moist to dry with increasing temperature along the sequence) were investigated: 10 soil profiles (Typic Haplocryoll) in a tundra ecotone, 10 soil profiles (Ustic Haplocryoll) in a pine-fir forest and 20 soil profiles (Ustic Argicryoll) in sagebrush. All soils developed on granitoid moraines. Soil mineralogy was analysed using cathodoluminescence and X-ray diffraction. This revealed that biotite and plagioclase were both weathered to smectite while plagioclase also weathered to kaolinite. Cooler, wetter, altitude-dependent conditions promoted weathering of primary minerals. Furthermore, the soils of the tundra and forest zone exhibited a higher acidity and more organic carbon. In a series of wet laboratory batch experiments, materials from topsoils (A horizons) and subsoils (B horizons) in each ecotone were examined alone or in combination with other samples. In a first step, aqueous extracts of the topsoil samples were generated in batch reactors and analysed for the main ions. In a second and a third step the topsoil extracts were reacted with the subsoil samples of the same ecotone, and with the subsoil samples of the ecotones at higher altitude. The total duration of these batch experiments was 1800 h, and the solutes were measured using ICP-OES and ion chromatography. Dissolved Ca, Mg and K were mainly ...