Geochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica

• Published in: Biogeosciences
• Main Authors: M. A. Diaz, C. B. Gardner, S. A. Welch, W. A. Jackson, B. J. Adams, D. H. Wall, I. D. Hogg, N. Fierer, W. B. Lyons
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Antarctic; McMurdo Dry Valleys; East Antarctic Ice Sheet; Shackleton; Transantarctic Mountains; Shackleton Glacier; Antarc*; Antarctica; Ice Sheet
• Online Access: https://doi.org/10.5194/bg-18-1629-2021; https://doaj.org/article/e71c66bc17914a0fbdd188d1949659da

Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier ( ∼ 85 ∘ S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 µ g g −1 , while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with R 2 values for total water-soluble salts, water-soluble N:P , ClO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a30bfde58a9ca9c078104c9522588f76"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-18-1629-2021-ie00001.svg" width="9pt" height="16pt" ...