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 decrease.[3]
A survey in 1985 concluded that only 26 square kilometres (10 sq mi) of oak savanna remain, roughly 0.02% of what is estimated to have existed at the time of European settlement. Highly dispersed and fragmented, none of the present habitat falls under the designation of National Forests but comes under the administration of the states' Department of Natural Resources organizations or federal entities such as the Fish and Wildlife Service. Remaining intact habitat areas include:[5]
^Mabry, Catherine M.; L.A. Brudvig; R.C. Atwell (2010-06-15). "The confluence of landscape context and site-level management in determining Midwestern savanna and woodland breeding bird communities". Forest Ecology and Management. 260 (1). Elsevier B.V.: 42–51. doi:10.1016/j.foreco.2010.03.028.