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Displaying entries 61 - 80 of 128 in total

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...
Complete
2019-08-02 13:49:35 -0800
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Circumpolar Arctic AVHRR NDVI Trend 1982-2008 (Bhatt et al. 2010)

Aga circumpolar avhrr ndvi 1995 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-15 13:35:35 -0800
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Circumpolar Arctic AVHRR Summer Warmth Index 1982-2003 (Raynolds et al. 2008)

Aga circumpolar avhrr swi 1982 2003 Alaska Geobotany Center (AGC) - 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 [Circumpolar Arctic Vegetation Map](/catalog/entries/5503-circumpolar-arctic-vegetation-map-cavm-team-2003) **Map...
Complete
2019-08-15 13:37:09 -0800
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Circumpolar Arctic Bioclimate Subzones

Aga circumpolar bioclimate 2003 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-16 12:51:25 -0800
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Circumpolar Arctic Biomass (Raynolds et al 2012)

Aga circumpolar avhrr biomass 2010 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-15 13:30:05 -0800
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Circumpolar Arctic Biomass Trend 1982-2010 (Epstein et al. 2012)

Aga circumpolar avhrr biomass trend 1982 2010 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-15 13:31:21 -0800
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Circumpolar Arctic Coastline and Treeline Map

Aga circumpolar coastline treeline 2003 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-16 12:53:51 -0800
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Circumpolar Arctic Elevation Map

Aga circumpolar elevation 2003 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-15 13:50:14 -0800
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Circumpolar Arctic Floristic Provinces Map

Aga circumpolar floristic 2003 Alaska Geobotany Center (AGC) - 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....
Complete
2019-08-16 12:53:02 -0800
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Circumpolar Arctic Lake Cover Map

Aga circumpolar lake cover 2003 Alaska Geobotany Center (AGC) - Lake cover strongly affects the reflectance of the land surface over large areas of the Arctic, and was useful for identifying extensive wetlands. Lake cover was based on the number of AVHRR water pixels in each mapped polygon, divided by the number of pixels in the polygon. Since the imagery has a pixel size of 1 km^2, lake cover is underestimated for areas with many small lakes. Pixels within...
Complete
2019-08-16 12:48:07 -0800
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Circumpolar Arctic Landscape Map

Aga circumpolar landscape 2003 Alaska Geobotany Center (AGC) - The landscape map was derived from topographic data, regional physiographic maps, and visual interpretation of the AVHRR false-CIR image. Landscape codes were assigned to each of the vegetation polygons. For Greenland, Russia and the United States, detailed landscape maps formed the basis of the vegetation polygons (see vegetation mapping section). However, these regional landscape maps did not...
Complete
2019-08-19 14:03:55 -0800
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Circumpolar Arctic Substrate pH

Aga circumpolar substrate ph 2003 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-19 14:04:17 -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...
Complete
2019-08-26 13:22:51 -0800
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Circumpolar Arctic Vegetation Map (Vegetation Layer)

Aga circumpolar vegetation 2003 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-16 12:56:27 -0800
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Circumpolar Landscape Age Map (Raynolds et al. 2008)

Aga circumpolar landscape age 2009 Alaska Geobotany Center (AGC) - 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...
Complete
2019-08-16 12:55:40 -0800
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Current Turboveg Data Dictionary and Panarctic Species List (PASL)

Alaska Geobotany Center (AGC) - These are the most recent Data Dictionary (pop-ups) and Panarctic Species List (PASL) zip files for all the vegetation plot data entered into Turboveg for the Alaska AVA. These files are necessary to correctly use the Turboveg data with regards to coded data. The Data Dictionary file will be updated when new datasets are entered into Turboveg which result in additions to coded data such as...
Ongoing
2015-06-24
2019-08-15 13:05:13 -0800
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Deadhorse Patterned-Ground 10 x 10 m Grids

Aga deadhorse vegetation 2006 Alaska Geobotany Center (AGC) - The Deadhorse patterned-ground grid is located near the industrial center of Deadhorse, AK, within 15 km of the Beaufort Sea coast. There is one 10 x 10 m grid, with a complex of vegetation types created by non-sorted circles, with sparser vegetation in the circles and more continuous vegetation between the circles. Back to: [Patterned-Ground 10 x 10 m...
Complete
2019-08-16 14:00:04 -0800
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Ecosystems of Northern Alaska (Jorgenson & Heiner 2003)

Noak ecosystems poster%202010 preview Alaska Geobotany Center (AGC) - Map image, GIS data and publication pending - This map was funded by The Nature Conservancy to provide a seamless ecological context for analysis of the distribution of biodiversity in the Northern Alaska ecoregion. It covers all of Alaska north of the latitudinal treeline on the southern side of the Brooks Range. It includes of the Alaska North Slope and most of the Brooks Range. It is in...
Complete
2019-08-16 13:15:11 -0800
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Fish Creek Maps

Alaska Geobotany Center (AGC) - In Progress: Maps will be available from the following publications: Komarkova & Webber 1978 and Komarkova 1985.
Ongoing
2019-08-15 13:07:14 -0800
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Franklin Bluffs Patterned-Ground 10 x 10 m Grids

Alaska Geobotany Center (AGC) - The Franklin Bluffs patterned-ground grids are located in Subzone D, on the coastal plain of the Alaska North Slope, just west of the Sagavanirktok River. There are three 10 x 10 m grids: one near the rim of an abandoned river terrace (dry), one on the same terrace, but further back from the edge and a little lower in elevation (mesic), and one on the lower abandoned river terrace below the...
Ongoing
2019-08-20 14:00:50 -0800
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