INTEGRATING INFORMATION ON SURFICIAL GEOLOGY, SOILS, VEGETATION, AND ECOLOGICAL UNITS IN ASSESSING FIRE REGIMES AND RISK IN THE LAKE STATES

Over the past century, fire suppression, logging, and land conversion have fundamentally altered the forestlands of Michigan, Minnesota, and Wisconsin. In cases, changes in landscape patterns, incidence of insect infestation, and age-class distributions have led to serious forest health and fire risk concerns, particularly in pyrophilic ecosystems. These risks are amplified by social conditions including interspersed private and public lands, and high concentrations of permanent and recreational homes embedded within forestled areas. We are mapping landscape ecosystems at a scale of 1:250,000 and networking units into seven categories of historical disturbance regimes. Disturbance regime categories, ranging from short-interval community maintenance and stand-replacing fires to extremely long-interval stand-replacing fires, are based on a comprehensive literature review. Maps are being produced using georelational databases including landform and surficial geology, pre-European settlement vegetation, current vegetation classified from LANDSAT Thematic Mapper satellite imagery, Natural Resource Conservation Service soil surveys, ecological unit maps (Subsections and Landtype Associations), and digital elevation models. A modern fire (1985-1995) and historical fire (mid-1800’s) database has been produced. The hypothesis that historical and modern fire frequencies and rotation intervals are significantly different among ecological units will be tested a’ posteriori. Moreover, the two principal measures of fire regimes, fire frequencies and fire rotations, provide critical information on fire risk, and meaningful estimates of these measures require clearly specifying the location and size of the area of interest. Thus identifying ecologically homogenous areas within which fire regimes can be analyzed and reported is an essential step in the assessment of fire risk. Final maps, interpreted in conjunction with information on current ecological and social conditions, will be useful for prioritizing fuel and fire management needs, and assisting land managers in developing fire and fuel management plans.