Experimentally increased snow accumulation alters soil moisture and animal community structure in a polar desert

Snow accumulation can influence soil properties in arctic and alpine tundra, boreal and temperate forests, and temperate grasslands. However, snow may be even more influential in arid ecosystems, which by definition are water limited, such as the hyper-arid polar desert of the McMurdo Dry Valleys, Antarctica. Moreover, snow accumulation may be altered by climate change in the future. In order to investigate the impact of changes in snow accumulation on soils in the McMurdo Dry Valleys we experimentally manipulated the quantity of snow at two locations and monitored soil properties over 5 years in relation to a snow depth gradient created by snow fences. We predicted that increased snow depth would be associated with increased soil moisture and a shift in soil animal community structure. While we did not observe changes in soil biochemistry or community structure along the snow depth gradient at either site, increased snow accumulation caused by the snow fence altered soil properties across the entire length of the transects at one site (Fryxell), which collected substantially more snow than the other site. At Fryxell, the presence of the snow fence increased gravimetric soil moisture from 1 to 5-9%. This was associated with a decline in abundance of the dominant animal, Scottnema lindsayae, a nematode typically found in dry soil, and an increase in Eudorylaimus sp. a nematode associated with moist soil. We also observed changes in soil pH, salinity, and concentrations of inorganic nitrogen and chlorophyll a over the course of the experiment, but it was difficult to determine if these were caused by snow accumulation or simply represented temporal variation related to other factors.