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View of the bay of Green Bay.
Cofrin Center for Biodiversity

Northern Lake States

The information provided in this web site centers on the northern forest regions of Minnesota, Wisconsin, and Michigan, with special emphasis on northeastern Wisconsin. This geographic area encompasses the western portion of the Laurentian Mixed Forest Province, as described by the U.S. Forest Service classification of ecoregions in the United States (Bailey 1995). The vegetation and biological communities of this region are transitional between the boreal forest region to the north and the broadleaf deciduous forests of eastern North America. Because the growing season is short (approximately 100-140 frost free days), much of the region has been left or has reverted to forest, providing a major refugium for animal and plant species which have disappeared from other parts of the United States. Opportunities for outdoor recreation and nature appreciation are abundant, including six national forests, four national park units, and numerous state and county forests, parks, and wildlife areas.

Vegetation of the Northern Lake States

Prior to settlement by Europeans in the late 1800's the northern portions of Michigan, Wisconsin, and Minnesota were covered by closed canopy forests of northern hardwoods and conifers interspersed with lakes, wetlands, and rivers. The forest landscape hadn't changed drastically for at least the previous 3000 years (Davis 1981), although local variations in soil and topography, coupled with disturbances by windstorms and fires created a mosaic of different forest types. Detailed reconstructions of the original vegetation have been derived from General Land Office surveys for Wisconsin (Finley 1976) and Minnesota (Marschner 1975), while an older map exists for Michigan (Veatch 1928). According to Frelich (1995), the pre-settlement distribution of forest types in this region consisted of the following major forest types:

Approximately 68% of the 32.7 million hectare forest area consisted of old growth, only 1.1% of which remains today. According to Frelich (1995), about 4.4% of the old growth swamp conifers survived the logging era, along with 0.2% of old growth northern hardwoods, 0.6% red-white pine, 2.6% spruce-fir-birch, 0.02% oak-hickory, 0.2% river bottom forests, and 3.0% jack pine. By far the largest area (approximately 40%) of remnant old growth forest occurs in the Boundary Waters Canoe Area (BWCA) of northeastern Minnesota. Other significant areas of old growth forest exist in the Porcupine Mountains State Park of Upper Michigan, Sylvania Wilderness Area in the Ottawa National Forest, and private lands in the Huron Mountains northwest of Marquette, Michigan.

Today, the Northern Lake States landscape is still dominated by forests, but their age and composition have been modified extensively by human activities. In particular, early successional stands of aspen and paper birch have replaced much of the vast old growth hardwoods and pines. Northern hardwoods still cover much of northern Wisconsin and Upper Michigan, but most of the forest consists of young or moderately aged trees that are harvested periodically.

Current vegetation maps of the Northern Lake States are now available through interpretation of satellite images. Although age of the forest typically is not depicted on these maps, they provide useful tools for resource management and for assessing the potential distribution of plants and animals.

Regional Information Sources

Many excellent information resources are available to help you explore the biodiversity and ecology of the Northern Lake States. The following websites provide original information about our region, and most include links for finding additional details. Click on the name in the table to be transferred to the corresponding site. Also see above for information about national forests, national park units, and other highlights of the Northern Lake States.

Sponsored by the Great Lakes Commission, provides the most comprehensive source of information about the Great Lakes Basin.
Overview of Great Lakes ecosystems and numerous links to ongoing programs. Sponsored by U.S. Environmental Protection Agency.
Information about latest news and research in the Great Lakes. Also includes job listings and discussion board.
Central resource for information about Wisconsin natural resources and biodiversity. Use search facility for best access to this large and comprehensive site.
Central resource for information about Minnesota natural resources and biodiversity.
Central resource for information about Michigan natural resources and biodiversity.
Interagency clearinghouse of information sponsored by U.S. Forest Service, USDA and USDI Joint Fire Science Program and others. Reports section is especially valuable.
U.S. Geological Survey reference site with numerous links and articles about Great Lakes biological resources.
USFWS information resource for 8 state areas, including Minnesota, Wisconsin, and Michigan.