Functional diversity of soils along environmental gradients in the Ross Sea region, Antarctica

The University of Wisconsin Antarctic Soils database was used to examine soils at four sites along a latitudinal gradient that included Rennick Glacier (72°S), Taylor Valley (77°S), Hatherton Glacier (80°S), and Beardmore Glacier (85°S). The soils, derived from glacial drifts ranging from Holocene to Pliocene in age, were stratified at each site by microclimate into subxerous (coastal), xerous (valley floors and sidewalls), and ultraxerous (edge of polar plateau). Analysis of variance and principal components analysis were used to determine the relative influence of latitude, longitude (soil climate along the valley profile), and time of exposure on soil properties and diversity. Time of exposure is the most important factor influencing functional diversity of soils, including depths of staining, coherence, visible salts, and ghosts; depth of ice-cemented permafrost; maximum color-development equivalence; salt and weathering stages; thickness of the salt pan; salt concentration in the salt-enriched layer, and the profile salt content to 70 cm. Soil climate is important with regards to the amount of available moisture, which generally decreases from the coast inland. Soil climate is important with regards to most of the properties, primarily salt content and depth to ice-cemented permafrost; however, soil climate is interactive with time of exposure as the youngest glacial deposits are often along the coast and the oldest deposits are in ultraxerous, upland-valley cirques. Soil differences within a specific soil climate zone were minimal along the latitudinal gradient except for salt chemistry. The proportion of nitrate in soil–water extracts increased and the proportion of sulfate decreased with an increase in latitude. The results of this study have important implications regarding terrestrial biodiversity and ecosystem functioning.