The Blackland Prairies and Post Oak Savannah
Pre-settlement conditions of the western counties were that of a true prairie grassland community dominated by a diverse assortment of perennial and annual grasses and forbs (weeds). The fertile dark clay soils of the Blackland Prairies are some of the richest soils in the world. Many early settlers who first encountered the blackland prairie described it as a vast endless sea of grasses and wildflowers with sparsely scattered trees or mottes of oaks. Wooded areas were restricted to bottomlands along major rivers and streams, ravines, protected areas, or on certain soil types. People are often surprised to learn that trees, including some of significant size, comprise a part of the prairie ecosystem. Pecan, cedar elm, various oaks, and hackberry dot the landscape, with mesquite invading some areas. However, development and the suppression of natural fires have allowed more trees to flourish in this region than ever before. The dominant grass of this true tall-grass prairie is little bluestem, but big blue stem, Indiangrass, eastern gammagrass, switchgrass, and side oats grama can also be found. Today, only 5,000 of the original 12 million acres remain in true prairie condition.
The eastern counties of this region are part of the Post Oak Savannah Ecoregion. As the name implies, the original plant community associated with this region was a savannah dominated by native bunch grasses and forbs with scattered clumps of trees, primarily post oaks and blackjack oaks. Black hickory may also be locally abundant. Cedar elm, sugarberry, eastern red cedar, and common persimmon are also widespread. Forested areas were generally restricted to bottomlands along major rivers and creeks, or in areas protected from fire. Historically, wide vistas of tall-grass – little bluestem, Indiangrass, switchgrass, and a myriad of wildflowers were broken only by the occasional group of trees giving the landscape a park-like atmosphere. Peat bogs mingled amongst stands of flowering dogwood, sassafras, bumelia and yaupon are also found here. Soils within the area are unique. Sands and sandy loams are predominantly found on upland sites, while clay or clay loams are typically associated with bottomlands. A dense clay pan, that is almost impervious to water, underlies all soil types within the region at depths of only a few feet.
For more information on the historical perspective of this region, please see http://www.tpwd.state.tx.us/landwater/land/habitats/post_oak.
Adapted from Texas Parks & Wildlife Department, http://www.tpwd.state.tx.us