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Data format: Shapefile File or table name: veg units Theme keywords: AVHRR, vegetation, map, Image, NDVI, Raster, CAVM |
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Abstract:
Vegetation map
The CAVM map is a single ARC/INFO polygon coverage. Each polygon within this coverage has 7 attributes in common: bioclimatic subzone, floristic province, substrate chemistry, percent lake cover, landscape, and vegetation. During the production of the map, coverages were created for each separately mapped area. These were then combined for the final map into a single coverage.
Vegetation, especially in the Arctic, is not homogeneous. Thus, each CAVM polygon, which covers at least 50 km2, contains many vegetation types. The map portrays the dominant zonal vegetation. This is the vegetation that develops under the prevailing climate, uninfluenced by extremes of soil moisture, snow, soil chemistry, or disturbance. Zonal sites are flat or gently sloping, moderately drained, with fine-grained soils. Areas of extensive azonal vegetation, those that are dependent on specific soil or hydrological conditions, such as mountain ranges, large wetlands, and river systems, were also mapped. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
Vegetation map The CAVM map is a single ARC/INFO polygon coverage. Each polygon within this coverage has 7 attributes in common: bioclimatic subzone, floristic province, substrate chemistry, percent lake cover, landscape, and vegetation. During the production of the map, coverages were created for each separately mapped area. These were then combined for the final map into a single coverage. Vegetation, especially in the Arctic, is not homogeneous. Thus, each CAVM polygon, which covers at least 50 km2, contains many vegetation types. The map portrays the dominant zonal vegetation. This is the vegetation that develops under the prevailing climate, uninfluenced by extremes of soil moisture, snow, soil chemistry, or disturbance. Zonal sites are flat or gently sloping, moderately drained, with fine-grained soils. Areas of extensive azonal vegetation, those that are dependent on specific soil or hydrological conditions, such as mountain ranges, large wetlands, and river systems, were also mapped.
Vegetation greenness is calculated as: NDVI = (NIR - R) / (NIR + R), where NIR is the spectral reflectance in the AVHRR near-infrared channel (0.725-1.1 5, channel 2) where light-reflectance from the plant canopy is dominant, and R is the reflectance in the red channel (0.58 to 0.68 5, channel 1), the portion of the spectrum where chlorophyll absorbs maximally. The resulting image shows the Arctic with minimum snow and cloud cover. The selected pixels were then printed as a false-color CIR image (RGB = ch. 2, ch. 1, ch. 1).
publication date
Data provided by the Alaska Geobotany Center are copyright protected under the provisions of a Creative Commons Attribution-NonCommercial-ShareAlike License (http://creativecommons.org/licenses/by-nc-sa/1.0/). Materials may be freely downloaded, reprinted and redistributed for non-commercial use. Reproduction and redistribution of the materials on this web site, including derivative works, shall give credit to the Alaska Geobotany Center and remain subject to the above license. Any web pages that use this material shall contain a link pointing to the Alaska Geobotany Center home page (http://www.geobotany.uaf.edu/).
Institute of Arctic Biology
University of Alaska Fairbanks
(AVHRR) data were obtained from theUSGS Global AVHRR 10-day composite data. (http://edcdaac.usgs.gov/1KM/1kmhomepage.asp). Glaciers and oceans were masked out using information from the Digital Chart of the World (ESRI 1993).
The map was reviewed by the CAVM mapping team.
Coverage topology was checked using the NODEERRORS and LABELERRORS commands.
complete
Polygon boundaries were overlaid on the false-color infrared basemap and visually inspected.
False-color infrared basemap, NDVI
Digital elevation model
coastline and glacier masks
Coastline and glacier polygons that had an area < 49,000,000 square meters were deleted from the dataset by the ELIMINATE command.
Coastlines were simplified to a weed tolerance of 5000 m using the bendsimplify option.
Cleaned simplified coastline with a fuzzy tolerance of 500 m.
Repeated step 1 (deleted all Coastline and glacier polygons that had an area < 49,000,000 sq m)to remove any small polygons that may have been created during the clean process.
Metadata imported.
Metadata imported.
Internal feature number.
ESRI
Feature geometry.
ESRI
Alaska Geobotany Center
University of Alaska Fairbanks
none
Institute of Arctic Biology
University of Alaska Fairbanks