Variation in the characteristics and development of soils at Edmonson Point due to abiotic and biotic factors, northern Victoria Land, Antarctica

Abstract

The lack of baseline surveys of soil environments in many areas of Antarctica provides an impediment to understanding their suitability for supporting biotic communities and limits abilities to monitor and predict impacts of environmental changes. A soil survey was conducted at Edmonson Point (Victoria Land) within representative local environments to identify their variability and drivers of soil processes and geochemistry. The soils were coarse-textured and lacked cohesion and structural development. The parent material was homogenous, and consisted of weathered and unconsolidated basaltic lavas and scoria. Despite these similarities, the soils varied significantly with the variation driven by local environmental and biotic factors. Penguins had the greatest influence, deposited guano altered soil processes leading to profound changes in soil characteristics. The ornithogenic soils were rich in penguin bio-elements, with low C/N, high EC and large variation in pH. Contents of N and C declined at comparable rates as C/N values did not change with time. Ornithogenic P was not readily lost, resulting in its high concentrations in relict soils. Abundant bacteria played a key role in these processes, but after cessation of guano inputs bacterial numbers and activity declined considerably. Alternatively, rich autotrophic microflora had a little influence on ornithogenic soil geochemistry. Characteristics and development of mineral soils were driven by hydrology and associated biological processes. Dry fellfield soils were the most immature, as indicated by more coarse-grained material, neutral pH, low EC and C/N values, scarce microflora and elemental content corresponding to typical background values. Alternatively, soils from moss communities and wetlands had higher amounts of fine-grained material, C, N and C/N values and lower pH that resulted from accumulation of organic matter. Elemental concentrations in soils from moss communities were similar to those in fellfields, but were elevated in wetland soils. While C and N contents seemed to be controlled by biotic communities, geochemistry of other elements was driven by external inputs. Although some inputs may originate from substratum weathering in the surrounding areas, marine-derived elements redistributed with penguin guano seemed to be the major source of the enrichment. Analyses of the origin and distribution of the soil elements may provide valuable records for reconstruction of geochemical and environmental processes in Antarctic terrestrial ecosystems.