Earth Partnership for Schools


General Characteristics


Distribution: Southern dry and dry-mesic forests originally covered 1,386,700 acres or 3.96% total land surface of Wisconsin.

History: According to pollen records, oak forests were present about 6000 years ago. The glaciers left 10,000 to 12,000 years ago. Northern forest communities grew in southern Wisconsin between the time the glaciers left and the colonization by southern plant communities.

Before European settlement a transitional woodland composed of the most fire-tolerant trees—the oaks—stood between maple and conifer forests and the prairies. Where these trees were most widely scattered—pioneers called them oak openings, oak savannas or oak barrens. Where trees grew more closely together—pioneers called them oak woodlands or forests. There was no clear line between prairies and savannas, nor between savannas and woodlands. Their arrangement on the landscape was shaped by fire behavior, which was constrained by topography, location of villages, etc. For example, prairies were more common on southwest facing slopes, on flat areas unbroken by streams and near villages; woodlands were more common in highly dissected topography (Driftless area), northwest slopes and northeast of rivers and lakes. Following European settlement and subsequent decrease in wild fires, many woodland, savanna, and prairie areas grew into thickets. Much of the wooded area of southern Wisconsin is more thickly populated with trees than was in the past. On suitable sites with nearby maples for seed sources, some former oak woodlands have become maple forests.

Physical Environment: Southern oak forests are located on sandy or well-drained flatlands, or on thin soils on hilltops and ridges.

Microclimate: The light intensities are moderate to high in oak forests. Direct sun exposure accelerates evaporation, increases temperatures, and creates an arid climate.