HR: 0800h
AN: B51A-0193    [Abstracts]
TI: Soil Nitrogen Cycling Associated With Small Patterned Ground Features Along a High-Latitude Temperature Gradient in Northern Alaska
AU: * Kelley, A M
EM: amk5d@virginia.edu
AF: Department of Environmental Sciences, University of Virginia 291 McCormick Rd P.O. Box 400123, Charlottesville, VA 22904-4123 United States
AU: Epstein, H E
EM: hee2b@virginia.edu
AF: Department of Environmental Sciences, University of Virginia 291 McCormick Rd P.O. Box 400123, Charlottesville, VA 22904-4123 United States
AU: Walker, D A
EM: ffdaw@uaf.edu
AF: Alaska Geobotany Center, Institute of Arctic Biology University of Alaska Fairbanks PO Box 757000, Fairbanks, AK 99775-7000 United States
AB: Patterned ground (surfaces that display ordered and relatively symmetrical morphological patterns) is common in regions of permafrost. Non-sorted circles, also known as frost boils, are a type of patterned ground that occurs throughout arctic tundra. They are defined as small circular areas, 0.5 to 3 m in diameter, with little to no vegetation, which lack a border of stones. In some areas non-sorted circles can make up 70% of the ground surface at a local scale. The amount of vegetation present on non-sorted circles varies with latitude, due to the effect of temperature on plant production. The availability of nitrogen is a major limitation to the growth arctic tundra vegetation. Few studies have examine the role of nitrogen limitations to growth of vegetation on patterned ground features, and instead have focused on the role of physical disturbance, such as frost heave, on the vegetation. In addition to lacking vegetative cover, these non-sorted circles have lower amounts of soil organic matter, which cause differences in the soil properties, especially in regards to plant-available nitrogen. We measured total organic carbon and nitrogen, as well as nitrogen mineralization at four sites in northern Alaska, along a high-latitude temperature gradient. At each site we compared nitrogen availability of non-sorted circles to the surrounding, inter-circle tundra. Initial results indicate that the availability of ammonium and nitrate are highest beneath the most vegetated surfaces because of the larger amounts of organic matter present in the soil. This nutrient availability is greater at the more southern sites because of the warmer climate. These results give us insight into the close connection between vegetation cover and soil nutrient availability in arctic ecosystems. Examining soil nutrient availability along a latitudinal gradient provides information on how temperature influences plant-nutrient relations in these patterned-ground systems.
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005