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Natural Disturbances

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Lake States Fire Database

The Lake States Fire Database is an extensive set of spatial fire information covering the northern Great Lakes region. As a record of wildfire activity in the northern parts of Minnesota, Wisconsin, and Michigan, this data set is the first to unify fire records for the multi-state area.

Produced as part of the Great Lakes Ecological Assessment Fire Project under a cooperative agreement between the USDA Forest Service and the University of Wisconsin-Madison, the Lake States Fire Database was produced using fire data from four agencies. The Departments of Natural Resources of Minnesota, of Wisconsin, and of Michigan, and the USDA Forest Service each contributed information for wildfires that occurred within their jurisdictions from 1985-1995. The fire database contains the origin location and final size for over 18,000 fires in the region over these 11 years. Data were gathered for those wildfires occurring in areas where the Departments of Natural Resources or USDA Forest Service had primary suppression responsibility. The final study area consisted of the intersection of those primary-suppression areas and those counties to the north of or containing the border for the Laurentian Mixed Forest Province (Bailey 1995).

Creation of a useable fire data set from the agencies' contributions necessitated transformation of fire location information to a spatially explicit coordinate system. Almost all fire origin information had been recorded using the Public Land Survey System (PLSS), which allowed for the location of a fire to the nearest 1 mi2 (2.59 km2). Transformation tables were used to convert the PLSS descriptions of fire origin locations to a set of state-specific coordinate systems. These state-specific systems were then projected onto an Albers Equal-Area Conic projection centered over the northern Lake States region. This allowed, for the first time, fire patterns to be displayed across multiple states and agency boundaries.

Although the vast majority of fires during this time period were small, a sizeable number were quite large.  By segregating fires using size thresholds, the Lake States Fire Database can, for the first time in this region, show the spatial patterns of fire activity. For example, it is possible to view all fire reports, all fires larger than or equal to 1 acre, all fires larger than or equal to 10 acres, all fires larger than or equal to 100 acres, and all fires larger than or equal to 1000 acres.

Gridded Framework

A set of grids was superimposed onto the northern Lake States region to provide a systematic framework to assess fire occurrence and density. Grids with resolutions of 10 km, 5 km, 3 km, and 2 km were used to explore the Lake States Fire Database; this framework allowed us to create raster maps showing fire attributes. For example it was possible to create an occurrence map showing which cells, using a 10 km resolution, witnessed a fire of size larger than or equal to one acre during the 1985-1995 period. Large-fire patterns can be assessed by showing only those cells containing a fire larger than or equal to 100 acres.

By counting the number of fires of a given size within a cell, it is possible to display, for example, maps of counts larger than or equal to 1 acre and of counts of fires larger than or equal to 100 acres.

The Lake States Fire Database can be used to investigate, for the first time, the spatial variation of fires across the entire northern Lake States region. By comparing it with the Fire Factor Database , it is possible to investigate which abiotic, biotic, and human factors may be associated with the occurrence or frequency of fires in the region.

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