PARENT SESSION
Poster Session # 10: Soil Ecology.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Plant community and ecosystem properties in Arctic frost-boil systems.
Kelley, Alexia1, Epstein, Howard*,1, Walker, Donald2, 1 University of Virginia, Charlottesville, VA2 Univeristy of Alask Fairbanks, Fairbanks, AK
ABSTRACT- Frost boils are a type of patterned ground formation that is common in arctic ecosystems. These landscape features, typically 0.5 to 3 m in diameter, are initially formed through differential freezing and thawing of soils (cryoturbation) and may persist on the landscape for long periods of time. The disruption associated with soil heaving causes frost boils to be distinctly different in terms of plant community structure and soil biogeochemistry from the surrounding inter-boil areas. The properties of frost-boil ecosystems are strongly influenced by regional climate gradients. In this study we are investigating the interactions among nutrient cycling, plant communities, and cryoturbation. Soil biogeochemistry and plant community traits of frost boils and inter-boil areas were examined along a latitudinal climate gradient in arctic Alaska. Preliminary data from three sites on the Arctic Slope of Alaska show that Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI) of frost boils (average NDVI across sites = 0.41, average LAI across sites = 0.19) are less than those of inter-boil areas (average NDVI = 0.54, average LAI = 0.88). Both NDVI and LAI decrease with increasing latitude, however the NDVI values on frost boils decrease more rapidly than those outside of frost boils. Thaw depth is between 19 to 29 cm deeper in frost boils than inter-boil areas and is on average 23 cm deeper at the more northern sites, as compared to the more southern study sites, due to the insulating effect of vegetation on soils. Soil moisture is lower in frost boils (mean of 42.3% by volume) than inter-boil areas (mean of 70.2%), largely because of greater mineral soil content and less organic matter in frost boil surface soils. This work is part of a larger study that seeks to understand the relationships among frost boils, climate, vegetation, and nutrient cycling.
Key words: plant communities, arctic tundra, carbon and nitrogen cycling, frost boils