Upper Midwest forest-savanna transition

Upper Midwest forest-savanna transition
Ecoregion Preserve (Devil's Lake State Park, Wisconsin)
Ecology
Biome	Temperate broadleaf and mixed forest
Borders	Western Great Lakes forests Southern Great Lakes forests Central forest-grasslands transition Central tall grasslands Northern tall grasslands Canadian aspen forests and parklands Midwestern Canadian Shield forests
Bird species	215
Mammal species	62
Geography
Area	166,100 km2 (64,100 sq mi)
Countries	United States and Canada
States/Provinces	Minnesota, Wisconsin, Michigan, Iowa, Ontario and Manitoba
Conservation
Habitat loss	62.5%
Protected	4.7%

The Upper Midwest forest-savanna transition is a terrestrial ecoregion that is defined by the World Wildlife Fund. An oak savanna plant community located in the Upper Midwest region of the United States, it is a transitory ecotone between the tallgrass prairies to the west and the temperate deciduous forests to the east. A part of the Upper Mississippi River basin, it is considered endangered with less than 5% of the original ecosystem remaining intact, due mostly to overgrazing and conversion to agriculture.

Historically, wildfire has been the primary driver and determinant of the forest dynamics in the plant community. Due to this the resulting canopy structure has been relatively sparse (the basal area ranges approximately from 4 to 29 meters hectare⁻¹). Presence and biodiversity of plant species is largely controlled by the frequency of fire. Typical tallgrass prairie vegetation such as grasses, forbs, shrubs, and sedges, increase with an increase in the amount of fire, whereas tree density and basal area decreases.

After European American settlement and the abandonment of fire as a land management regime, most savannas have been converted into closed canopy woodlands, with shade tolerant and fire-intolerant species dominating rather than the historic primary and secondary succession species dependent on fire.