HR: 0800h
AN: C31A-1121    [Abstracts]
TI: Permafrost Thermal Properties and Thaw and its Relationship to Soil and Plant Cover, Lake Hovsgol, Mongolia
AU: * Goulden, C E
EM: cgoulden@acnatsci.org
AF: Academy of Natural Sciences, Mongolian Institute 1900 Benjamin Franklin Pkwy., Philadelphia, PA 19103 United States
AU: Etzelmuller, B
EM: bernd.etzelmuller@geo.uio.no
AF: University of Oslo, Department of Geosciences P.O. Box 1047 Blindern, Oslo, N-0316 Norway
AU: Ariuntsetseg, L
EM: ariunka_2001@yahoo.com
AF: Mongolian Academy of Sciences, GeoEcology Institute Baruun Selbe-15, Ulaanbaatar, 211238 Mongolia
AU: Nandintsetseg, B
EM: b_nandia@yahoo.com
AF: Mongolian Academy of Sciences, GeoEcology Institute Baruun Selbe-15, Ulaanbaatar, 211238 Mongolia
AU: Avirmed, O
EM: oggie_a@yahoo.com
AF: Mongolian Academy of Sciences, GeoEcology Institute Baruun Selbe-15, Ulaanbaatar, 211238 Mongolia
AU: Batkhishig, O
EM: o_batkhishig@yahoo.com
AF: Mongolian Academy of Sciences, Geography Institute, Ulaanbaatar, 210620 Mongolia
AU: Sharkhuu, A
EM: i_am_anaraa@yahoo.com
AF: Mongolian Academy of Sciences, GeoEcology Institute Baruun Selbe-15, Ulaanbaatar, 211238 Mongolia
AU: Sharkhuu, N
EM: sharkhuu_n@yahoo.com
AF: Mongolian Academy of Sciences, GeoEcology Institute Baruun Selbe-15, Ulaanbaatar, 211238 Mongolia
AB: Northern Mongolia represents the southern-most extension of continuous permafrost and the border of the Siberian taiga forest in Asia. The mountainous watershed valleys of Lake Hövsgöl are in a forest/steppe transition zone characterized by continuous permafrost in the upper valleys and ridge tops and discontinuous permafrost in lower valley areas. Valley bottoms and south-facing slopes have steppe vegetation dominated by grasses and sedges with increasing amounts of forbs in heavily grazed areas. North-facing slopes and ridges are covered by taiga forest, dominated by larch. The mean annual air temperature in the region is 4.5°C. Total annual precipitation averages about 300 mm with most falling in mid summer. The objectives of this research include the identification of the spatial distribution of permafrost and possible permafrost thaw associated with modifications in the watersheds due to nomadic pastoralism and to climate change. Permafrost thaw has been documented elsewhere at the Lake and there are indications that a severe thaw has occurred in the study area as a result of heavy pastoralism. We are monitoring changes and experimentally testing factors that maintain low soil temperatures and high soil moisture in six valleys that have similar meteorological conditions but affected by pastoralism ranging from heavy grazing in two northern valleys, to light or no grazing in two southern valleys, and moderate grazing in the middle two valleys. Soil temperature and soil moisture are measured in plots in each valley, composing a range of soil and plant densities and texture, largely dependent upon livestock grazing levels. Experiments are measuring decomposition rates for different plant taxa, and effect of different amounts of necromass cover on soil temperature and soil moisture. In this paper we contrast conditions in the six valleys. The area has warmed by 1.6°C between 1963 and 2004 (P <0.0001) but there has been no corresponding significant change in annual precipitation. There also has been a shift towards a longer growing season as a result of the warming trend. The objective of this presentation is to assess the highly complex relationships between climate warming, grazing, vegetation cover and the thermal state of permafrost. Permafrost and the active layer thickness is a governing factor for available soil moisture for plant growth, and thus affects the soil water balance. The increase of the active layer thickness rapidly leads to drying out the soils resulting in a change of soil thermal regime and vegetation composition. First model estimations show an increased evapotranspiration in the last 10 years. Ground temperatures are monitored in 16 boreholes in the region since 2002, and during this period some differences are evident, e.g., active layer thicknesses in morphometrically similar topographic positions are higher in grassed than in un-grassed settings. Comparable results of vegetation-permafrost interactions are revealed by an intensive measurement campaign of DC resistivity tomography.
UR: http://www.hovsgolecology.org
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
SC: Cryosphere [C]
MN: Fall Meeting 2005