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Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
The Circumpolar Arctic Vegetation Map: A Tool for Analysis of Change in the Arctic
Donald (Skip) Walker1, Martha Raynolds2, Hilmar Maier3
1Institute of Arctic Biology, University of Alaska Fairbanks, PO Box 757000, Fairbanks, AK, 99775, USA, Phone 907-474-2460, Fax 907-474-2459, ffdaw@uaf.edu
2Institute of Arctic Biology, University of Alaska Fairbanks, PO Box 757000, Fairbanks, AK, 99775-7000, USA, Phone 907-474-2459, Fax 907-474-2459, fnmkr@uaf.edu
3Institute of Arctic Biology, University of Alaska Fairbanks, PO Box 757000, Fairbanks, AK, 99775-7000, USA, Phone 907-474-1540, Fax 907-474-6967, fnham@uaf.edu
The Circumpolar Arctic Vegetation Map portrays the vegetation north of the Arctic tree line. Here we present the map with an an area analysis. Fifteen vegetation types are mapped based on the dominant plant growth forms. More detailed, plant-community-level, information is contained in the database used to construct the map. The reverse side of the vegetation map has a false-color infrared image constructed from Advanced Very-High Resolution (AVHRR) satellite-derived data, and maps of bioclimate subzones, elevation, landscape types, lake cover, substrate chemistry, foristic provinces, the maximum normalized difference vegetation index (NDVI), and aboveground phytomass.
The vegetation map was analyzed by vegetation type and biomass fore each county, bioclimate subzone, and floristic province. Biomass distribution was analyzed by means of a correlation between aboveground phytomass and the normalized difference vegetation index (NDVI), a remote-sensing index of surface greenness. Biomass on zonal surfaces roughly doubles within each successively warmer subzone, from about 50 g m-2 in Subzone A to 800 g m—2- in Subzone E.
But the pattern of vegetation increase is highly variable, and depends on a number of other factors. The most important appears to be the glacial history of the landscape. Areas that were glaciated during the late-Pleistocene, such as Canada, Svalbard, and Greenland, do not show such strong increases in NDVI with temperature as do areas that were not glaciated. Abundant lakes and rocky surfaces limit the greenness of these recently glaciated surfaces. The highest NDVI and phytomass are found in non-glaciated regions of Alaska and Russia. Soil acidity also affects NDVI patterns. In Subzone D, where the NDVI/ soil acidity relationship has been studied most closely, NDVI is greater on acidic surfaces.
This has been attributed to fewer shrubs and higher proportion of graminoids (more standing dead sedge leaves) on the nonacidic surfaces. The trend of higher NDVI on acidic surfaces holds for subzones A, B and C, and is probably caused by generally drier soils, with less production, on limestone-derived soils of the Canadian Arctic. The trend is less clear in Subzone E because of much fewer nonacidic surfaces, and the abundance of glacial lakes with low NDVI on the acidic shield areas of Canada. Future analyses of the circumpolar database will be directed at examining which geographic regions and vegetation types have shown the strongest increases, and how these are correlated with temporal temperature changes.
Abstract Categories: Changes on Land
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