GIS Data Coverages and Standards

Land use data were collected at two different scales. At a small scale (1:250,000), a statewide land use/cover was obtained from the U.S. EPA and at a large scale (1:24,000) land use data from several state and county agencies. Digital data was acceptable for the large scale analysis if the data met these requirements: 1) land use data was interpreted post 1985, 2) a minimum mapping unit (mmu) or resolution of 100 meters or less, and 3) a data dictionary existed for the data to track original analog data. Digital data was obtained both in raster and vector format. Digital data was obtained from the following agencies: MNDNR, LMIC, NRRI, MDA, Metropolitan Council, Bemidji State, Olmsted County Planning, and the Wadena SWCD. All GIS coverages were projected to the UTM projection using datum NAD83. Because each data set was developed for specific purposes (i.e. mapping cropland, mapping forest vegetation, etc.), the attribute classifications varied among the data sources both in quality and quantity. One classification scheme was chosen and each GIS data set was updated to conform to this classification scheme. LMIC's 17 category land use classification scheme was selected as a suitable classification scheme. In addition to the land use data, a statewide CRP layer has been obtained from the MDA to identify CRP (Conservation Reserve Program) lands and their intended uses.

National Wetland Inventories (NWIs) were obtained from the Minnesota Department of Natural Resources to supplement the quality of the general wetland land use category. This data was used to generate estimates of wetland extent in the vicinity of each site. Statewide digital coverages for hydrography, roads, public land survey boundaries, and county boundaries were also obtained to provide contextual features for analysis.

Assessment Protocols

A multiple-scale analysis was developed to perform the land use assessment. The 120 sites was evaluated at multiple scales from as a large as a watershed perspective to a site specific scale. Criteria for data standards were established at two different levels.

Watershed analysis

First, at the watershed scale, the analysis utilized the field observations conducted at each site and a statewide digital land use/cover layer completed in the late 1970's by the U.S. EPA. If a watershed was less than 9 square miles in area, the field observation data were used to calculate the area of land uses for a given watershed. Land use was simplified into 7 categories (urban, agriculture, logged, forest, grassland, wetland, and lake). For each watershed, a given land use category was divided into 3 levels of use (1-20%, 21-60%, and 61-100%). If a given watershed was larger than 9 square miles, the GIS land use/cover layer was used to calculate the percentages of land use within a watershed. Since the land use/cover layer data was completed in the late 1970's, the 1992 agricultural census data was used to supplement the acreage of agricultural land that has been converted to CRP land. Estimates of CRP land were then added to the percentage of grassland in a watershed. Two series were excluded from the watershed analysis phase. Series 1 was excluded from this analysis due to the large acreage in each watershed (all watersheds were estimated to be over 1000 sq. miles). Series 6 was excluded due to the inability to accurately delineate the watershed boundary. Appendices in each series list each site and the estimated land uses for each site's watershed.

Proximity analysis

Land use was evaluated at varying proximities surrounding each site. Percentages of land use classes was calculated for each site at radii of 500m, 1000m, 2500m, and 5000m. Series specific analysis was conducted on other landscape pattern parameters.

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