AGLL 1004 Example: Edwards Plateau Region of Texas

Explore the Edwards Plateau region of Texas

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Elevations range from 600 feet above sea level in the eastern canyons to 3,000 feet above sea level in the ridges of the central and western regions.

Levels vary from 23 to 35 inches per year.

The features are round, often with rolling hills. It is thought of as a southern extension of the Great Plains.

Most of the Edwards Plateau contains mottled yellowish clay or clay loam surface soil with rocky clay or solid limestone rock layers underneath. Erosion has left much of the region with top soils of less than 10 inches.

The Edwards Plateau is characterized by a combination of tall, medium, and short grasses, including little bluestem, sideoats grama, switchgrass, Indiangrass, Texas wintergrass, and three-awn often intermixed into a woodland setting with hardwood trees such as escarpment live oak, Texas oak, honey mesquite, and with coniferous Ashe juniper. Protective canyons, especially on the eastern and southern portions of the plateau, provide for a great diversity of other hardwood species, such as Texas madrone, escarpment black cherry, Texas mountain-laurel, Mexican plum, Carolina basswood, lacey oak, and bigtooth maple. Springs and creeks found in these canyons are typically lined with bald cypress, sycamore, and black willow.

Prior to heavy settlement, fire played a major role in shaping the vegetation on the Edwards Plateau. Fire occurred on much of the land every 2-10 years. During this interval, Ashe juniper was kept out of most uplands by fire and dense grass competition. Other trees such as escarpment live oak and honey mesquite were kept more isolated among the grasses. Concentrated livestock grazing reduced the cover of grasses which suppressed wildfire and allowed trees to begin moving into the grasslands. Protected canyons and moist, north-facing slopes reduced the number and intensity of damaging fires, allowing many trees to persist prior to human settlement.

Bison were known to frequent the Edwards Plateau. Their migration in great numbers undoubtedly affected the landscape, plant communities, and the cultures of early human inhabitants. Later settlement brought primarily German farming communities and the adventurous livestock ranchers which have since been identified with Texas.

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Ecoregion maps and descriptions should only serve as background or preliminary information. Additional environmental information and/or testing (soil, water, salinity as needed) should be gathered before selecting vegetation. Contact your local land grant institution and state botanic gardens to learn more about your local ecoregions.