PARENT SESSION
Contributed Oral Session 107: Soil Biota and Communities
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal
Soil biodiversity and ecosystem functioning across a latitudinal gradient in Victoria Land, Antarctica.
Barrett, John*,1, Virginia, Ross1, Wall, Diana2, Adams, Bryon3, Cary, Craig4, 1 Dartmouth College, Hanover, NH, USA2 Natural Resource Ecology Laboratory, Ft. Collins, CO, USA3 Brigham Young University, Provo, UT, USA4 University of Delaware, Lewes, DE, USA
ABSTRACT- In Antarctic soil ecosystems, low temperatures and the availability of liquid water limit biodiversity and biotic activity. In this polar desert, environmental gradients are structured on local scales by proximity to melt streams and lakes, and regionally according to latitudinal variation in climate. Sensitivity of biological communities to climate change will therefore depend upon proximity to sources of water and the duration of frost-free days when liquid water is available, as well as the magnitude and sign of changes in temperature. We report on work in Victoria Land Antarctica spanning 72-83 degrees South, investigating the structure and functioning of soil communities and their sensitivity to climate variability. The goal of this project is to evaluate the relative importance of climate vs. biotic influences on ecosystem functioning. We characterized invertebrate communities and soil chemistry in surface soils from 6 sites across this gradient. Subsets of these sites were selected for intensive investigation of soil communities (microbial and invertebrate) and ecosystem functioning (soil respiration and nutrient mobilization). Preliminary results indicate that biological communities vary significantly across the gradient following predicted decreases in taxon richness at higher latitudes. There was also a high degree of variability in soil communities encountered over local scales (< 1km) due to variation in habitat suitability imposed by proximity to water sources and differences in soil chemistry, especially organic matter content. Soil respiration was influenced by soil temperature and moisture, and exhibited strong diel patterns coinciding with temporal variability in energy balance and soil temperature. Q10s fit to soil respiration data indicate that soil respiration in Antarctic soil communities may be 2-3 times as sensitive to small changes in temperature than soil respiration from temperate ecosystems. Our results indicate that Antarctic soil fauna have low thresholds for responding to spatial gradients in climate and soil properties, and are quite sensitive to small changes in temperature in space and time.
Key words: soil ecology, latitudinal transects, soil respiration, invertebrates