VARIATION IN BIOGEOCHEMISTRY AND SOIL BIODIVERSITY ACROSS SPATIAL SCALES IN A POLAR DESERT ECOSYSTEM

Desert ecosystems are characterized by distinct spatial patterning in soil biogeochemistry and biodiversity. In the Antarctic Dry Valleys, soil polygons are prominent features of the landscape and may be key units for scaling local ecological information to the greater region. We examined polygon soils in each of the three basins of Taylor Valley, Antarctica. Our objectives were to characterize variability in soil biogeochemistry and biodiversity at local to regional scales, and to test the influence of soil properties upon invertebrate communities. We found that soil biogeochemical properties and biodiversity vary over multiple spatial scales from fine ( 10 km) scales. Differences in biogeochemistry were most pronounced at broad scales among the major lake basins of Taylor Valley corresponding to differences in geology and microclimate, while variation in invertebrate biodiversity and abundance occurred at landscape scales of 10–500 m, and within individual soil polygons. Variation in biogeochemistry and invertebrate communities across these scales reflects the influence of physical processes and landscape development over ecosystem structure in the dry valleys. The development of soil polygons influences the spatial patterning of soil properties such as soil organic matter, salinity, moisture, and invertebrate habitat suitability. Nematode abundance and life history data indicate that polygon interiors are more suitable habitats than soils in the troughs at the edges of polygons. These data suggest that physical processes (i.e., polygon development) and biogeochemistry are important influences on the spatial variability of biotic communities in dry valley soil ecosystems.