Woodlands, or forests, are dynamic ecosystems that contain a large diversity of plant and animal life. Although generally described by their assemblage of trees they also contain shrubs, forbs, grasses, and sedges. Woodlands also contain a gamut of organisms ranging from bacteria and fungi to large mammals.
Woodlands continually undergo change. Succession refers to a process in which different species invade and occupy a site, only to be replaced in the future by other species. Changing conditions in sunlight, moisture, nutrient levels, and other factors control the type of species that can grow in the forest. Over time, natural forest succession usually changes a forest toward a composition of shade tolerant species. Periodic natural disturbances, such as fire, can delay or reset this succession process.
Oak savanna, also called "oak openings," was the dominant land cover type of southern Wisconsin before European settlement. This transition between the prairies of the Central Plains and the forests of eastern North America consisted of open-grown trees or fragmented forests where prairie grasses and wildflowers thrived within the openings. Bur Oak is the predominant tree found in oak savannas, however White Oak, Black Oak, Northern Red Oak, and Shagbark Hickory also grow in this ecotype.
Natural disturbances such as periodic wild fires minimized the extent of woody plants and maintained the relatively low percentage of canopy cover of savannas. Because of human manipulation of the land: fire suppression, heavy grazing by livestock, and effects of competing invasive plants, few healthy oak savannas now exist in southern Wisconsin.
Lands with moderate to dense tree coverage (50-100% canopy) which lie outside of wetlands are classified as upland woodlands. Upland woodlands typically contain a variety of deciduous hardwood species but are often identified by dominant tree species (Oak woods, Oak/Hickory woods, Maple/Basswood woods, etc.). If no species is particularly dominant they are sometimes termed “mixed hardwood forests.” At the climax of forest succession Sugar Maple and Basswood dominate the tree composition because of their ability to thrive in rather heavy shade. In Muskego, Maple/Basswood is considered the climax of forest succession. Many of the mixed hardwood forests in Muskego are former oak savannas.
Wisconsin's forests provide the clean air we breathe, help maintain the clean water we depend upon, and provide habitat for numerous species we enjoy. Tourism relating to woodlands is a significant contributor to the state's economy. Many recreational activities take place within Wisconsin's forests, such as hunting, camping, snowmobiling, hiking, and fishing. Without these ecological, economic and social values there would be an incentive to convert forests to other uses.