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16 results found Displaying all 16 entries

Circumpolar Arctic Substrate pH

Aga circumpolar substrate ph 2003 Differences in substrate chemistry have important effects on dominant plant communities. Some of the most important effects are related to soil pH, which governs the availability of essential plant nutrients. Soils in the circumneutral range (pH 5.5-7.2) are generally mineral rich, whereas the full suite of essential nutrients are often unavailable in acidic soils (pH < 5.5) or in soils...
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2018-08-09 15:11:47 -0800
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Circumpolar AVHRR Summer Warmth Index 1982-2003 (Raynolds et al. 2008)

Aga circumpolar avhrr swi 1982 2003 This data set was calculated from monthly AVHRR thermal infrared data (Comiso 2003). Summer Warmth Index (SWI) is the sum of monthly mean temperatures above 0 degrees Celsius. The months of May-September were evaluated for the years 1982 - 2003 (Raynolds et al. 2008). Back to <a href="/catalogs/9603-circumpolar-arctic-vegetation-map-all-layers">Circumpolar Arctic Vegetation...
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2018-08-09 15:11:57 -0800
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Circumpolar Arctic Bioclimate Subzones

Aga circumpolar bioclimate 2003 A fundamental problem for the CAVM is how to characterize the transitions in vegetation that occur across the roughly 10 °C mean July temperature gradient from the tree line to the coldest parts of the Arctic. Various authors, working with different geobotanical traditions, have divided the Arctic into bioclimatic regions using a variety of terminologies. The origins of these different terms...
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2018-08-09 15:11:59 -0800
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Circumpolar Arctic Floristic Provinces Map

Aga circumpolar floristic 2003 Floristic sectors characterize the considerable east-west floristic variation within the subzones. The more northern Arctic bioclimate subzones have a relatively consistent core of Arctic plant species that occur around the circumpolar region. Further south, local east-west variation is related to a variety of factors, including different paleohistories and the greater climatic heterogeneity....
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2018-02-22 11:54:39 -0900
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Circumpolar AVHRR NDVI Trend 1982-2010 (Bhatt et al 2010)

Aga circumpolar avhrr ndvi 1995 The normalized difference vegetation index (NDVI) is a measure of greenness. NDVI was calculated as: NDVI = (NIR - R) / (NIR + R), where NIR is the spectral reflectance in the AVHRR near-infrared channel (0.725-1.1 µm, channel 2) where light-reflectance from the plant canopy is dominant, and R is the reflectance in the red channel (0.5 to 0.68 µm, channel 1), the portion of the spectrum where...
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2018-08-09 15:11:48 -0800
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Circumpolar Arctic AVHRR False Color-Infrared (CIR) Map

Aga circumpolar avhrr cir 1995 Advanced Very High Resolution Radiometer (AVHRR) data were obtained from the USGS Global AVHRR 10-day composite data. (http://edcdaac.usgs.gov/1KM/1kmhomepage.asp)(Markon et al. 1995). Glaciers and oceans were masked out using information from the Digital Chart of the World (ESRI 1993). The image is composed of 1 x 1-km pixels. The color of each pixel was determined by its reflectance at the...
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2018-08-09 15:11:59 -0800
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Circumpolar Arctic Elevation Map

Aga circumpolar elevation 2003 Elevation strongly influences soil moisture and patterns of tundra plant communities. Areas less than 100 m above sea level were separated to show low-elevation plains. Areas above 100 m elevation were divided into 333-m intervals to show decreases of about 2 °C, as predicted by the adiabatic lapse rate of 6 °C per 1000 m. This corresponds to the change in mean July temperature between...
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2018-08-09 15:11:59 -0800
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Circumpolar Arctic AVHRR NDVI Map

Aga circumpolar avhrr ndvi 1995 The normalized difference vegetation index (NDVI) is a measure of greenness. NDVI was calculated as: NDVI = (NIR - R) / (NIR + R), where NIR is the spectral reflectance in the AVHRR near-infrared channel (0.725-1.1 µm, channel 2) where light-reflectance from the plant canopy is dominant, and R is the reflectance in the red channel (0.5 to 0.68 µm, channel 1), the portion of the spectrum where...
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2018-08-09 15:11:59 -0800
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Circumpolar Arctic Lake Cover Map

Aga circumpolar lake cover 2003 Percent lake cover strongly affects the albedo, or reflectance, of the land surface over large areas of the Arctic, and is useful for delineating extensive wetlands. Initially lake cover was derived from the AVHRR imagery in several different ways, producing maps that were used to help define vegetation polygons. For Russia, the Map of the World hydrology cover was converted to lake polygons,...
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2018-08-09 15:11:47 -0800
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Circumpolar Landscape Age Map

Aga circumpolar landscape age 2009 The landscape age map shows the length of time (in thousands of years) that Arctic landscapes have been available for plant colonization and the development of plant communities (Raynolds et al 2008). For most areas, this would be the time since the most recent deglaciation. Other areas first became available for plant colonization after emerging from under water due to drainage of glacial...
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2018-08-09 15:11:59 -0800
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Circumpolar Arctic Coastline and Treeline Map

Aga circumpolar coastline treeline 2003 The map extent is the Arctic, defined as the Arctic Bioclimate Zone, the area of the Earth with tundra vegetation and an Arctic climate and Arctic flora. It excludes tundra regions that lack an Arctic flora, such as the boreal oceanic areas of Iceland, the Aleutian Island, and the alpine tundra regions south of latitudinal tree line. Tundra is a physiognomic descriptor of low-growing vegetation...
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2018-08-09 15:11:47 -0800
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Circumpolar Landscape Map (Physiography)

Aga circumpolar landscape 2003 Elevation strongly influences soil moisture and patterns of tundra plant communities. Areas less than 100 m above sea level were separated to show low-elevation plains. Areas above 100 m elevation were divided into 333-m intervals to show decreases of about 2 °C, as predicted by the adiabatic lapse rate of 6 °C per 1000 m. This corresponds to the change in mean July temperature between...
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2018-08-09 15:11:58 -0800
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Circumpolar Arctic Biomass (Raynolds et al 2012)

Aga circumpolar avhrr biomass 2010 This map portrays an estimate of above ground plant biomass for the tundra biome based on trans-Arctic field data and AVHRR NDVI (Raynolds et al. 2012). Aboveground phytomass was sampled on transects along the Arctic bioclimate gradient in North America (1750 km long, 8 locations sampled 2003–2006) and Eurasia (1500 km, 5 locations sampled 2007–2010). The study locations were chosen to...
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2018-08-09 15:11:56 -0800
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Circumpolar Arctic Vegetation Map (CAVM Team 2003)

Aga circumpolar cavm 2003 side1 Alaska Geobotany Center (AGC) - The Circumpolar Arctic Vegetation Map (CAVM) is a geoecological map of the entire Arctic with a unified legend. It is the first vegetation map of an entire global biome at a comparable resolution. It was funded by the US National Science Foundation (OPP-9908-829), the US Fish & Wildlife Service, the US Geological Survey and the US Bureau of Land Management. The CAVM region is north of the...
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2018-08-09 15:11:57 -0800
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Circumpolar Arctic Vegetation Map (Vegetation Layer Only)

Aga circumpolar vegetation 2003 Mapped polygons at 1:7.5 million scale contain many vegetation types. The map portrays the zonal vegetation within each mapped polygon. Zonal sites are areas where the vegetation develops under the prevailing climate, uninfluenced by extremes of soil moisture, snow, soil chemistry, or disturbance, and are generally flat or gently sloping, moderately drained sites, with fine-grained soils...
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Circumpolar Biomass Trend 1982-2010

Aga circumpolar avhrr biomass trend 1982 2010 Trend in Arctic biomass was calculated from a linear regression of biomass values for all years 1982-2010 (Epstein et al 2012). Pixels with significant trends (p < 0.05) were retained. Biomass was calculated from the relationship between AVHRR NDVI and ground sampling of biomass, as described below: Aboveground phytomass was sampled on transects along the Arctic bioclimate gradient in North...
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2018-08-09 15:11:56 -0800
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