Abstract
Abstract. 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 µg 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 R2 values for total water-soluble salts, water-soluble N:P, ClO4-, and ClO3- of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.
Highlights
The least biologically diverse terrestrial systems are those found in extreme physical and chemical environments
Shackleton Glacier region surface soils can be separated into three zones based on their water-soluble geochemistry: an upper zone near the Polar Plateau, a middle zone near the center of the glacier, and a lower zone where the glacier flows into the Ross Sea (Figs. 1, 2)
The soil ecosystems found in the Transantarctic Mountains are among the least diverse on Earth, and their structure is influenced by environmental variables
Summary
The least biologically diverse terrestrial systems are those found in extreme physical and chemical environments. The abundance and diversity of life in soils are dependent on a number of environmental variables, including temperature, precipitation, organic matter content, and nutrient availability. Diaz et al.: Geochemical zones and environmental gradients (Wall et al, 2012). Hot deserts are typically viewed as one of the least biologically diverse environments, but cold deserts can often be even less diverse (Freckman and Virginia, 1998). Soils in Antarctica typically serve as end-members for low habitat suitability due to their high salt concentrations, low organic carbon, low soil moisture, and low mean annual temperatures (Courtright et al, 2001)
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