DOI 10.1007/s00300-009-0639-9ORIGINAL PAPER

tica, above-ground production is often limited to mosses and algae that occur near seasonally available liquid water such as ephemeral streams and ice-covered lakes. Com-pared to surrounding dry soils these critical transition zones are highly productive and harbor a more diverse assem-blage of soil animals, including rotifers, tardigrades, nema-todes and microarthropods. Current cooling trends punctuated by warming events, and predicted future climate warming are expected to aVect the hydrology of this region and thereby biodiversity and ecosystem functioning. Above-ground communities are exposed to more variable temperature, relative humidity and greater UV radiation, and may be more vulnerable to climate change than sedi-ments beneath, which are buVered from short-term changes. In this study, we compared above- and below-ground communities associated with either moss or cyano-bacterial mats along glacial-fed streams and lakes diVering in biological complexity (diversity, productivity and habitat suitability). All groups of soil fauna were more abundant in the above-ground material compared to the sediment beneath. Common indicators of habitat suitability (chloro-phyll a, soil pH, soil salinity, and soil nitrogen) did not diVer between vegetation types but were signiWcantly diVerent among sites. Variables most correlated with inver-tebrate abundances were sediment salinity, chlorophyll a content and nitrogen concentration. The McMurdo Dry Valleys are expected to become warmer and wetter as a result of climate change. This will likely increase the area of suitable habitat for most soil animals as areas of liquid water potentially increase and become available for longer periods of time