Post Oak Savanna
Source: Texas Parks & Wildlife
The original savannahs in the northern part of the Oak-Prairie region were characterized by native grasses such as little bluestem, silver bluestem, and brownseed paspalum with scattered clumps of trees. Post oak trees dominated, but other species included blackjack oak, water oak, winged elm, hackberry, and yaupon.
Fire working in concert with other factors such as drought, herbivory, and competition from grasses restricted shrub and tree growth and maintained the savannah. The natural fire frequency on level to rolling topography appears to have ranged from 5 to 10 years and on topography dissected with breaks and rivers the fire frequency may have been 20 to 30 years. Since the early 1800s, the suppression of fire, and soil disturbance and land clearing practices by farmers and ranchers have resulted in a higher density of smaller trees and more thick undergrowth of vegetation, especially yaupon.
Bottomlands in the early 1800s were typically composed of large hardwoods with very little understory vegetation. Many bottomlands have now been cut over and cleared. Others have thick understories resulting from timber cutting or various soil disturbances, or are relatively open due to continuous grazing. According to written accounts from early explorers and settlers in 1800s, white-tailed deer, wild turkey, bison, black bear, squirrel, mountain lion, and red wolf were once common in the Post Oak Savannah.
The most striking change to the savannah has been the degradation or loss of the native range grasses from overgrazing and the clearing of the native range to plant monocultures of improved grasses, such as coastal Bermudagrass, for cattle. The rich diversity of grasses and weeds in the native savannah provided food and cover for many wildlife species and the conversion to “improved pastures” is responsible for the decline and even disappearance of species such as the bobwhite quail in much of the area.