Claypan 23-30" PZ

Description

The Midgrass Prairie Community (1.1) is the interpretive plant community for the Claypan 23-30” PZ Ecological Site. The site developed as a treeless prairie with few scattered shrubs. Lotebush and ephedra were typical, but infrequent, shrubs. Vine-mesquite occupied favorable micro-sites and was locally dominant. Sideoats grama was the dominant or co-dominant grass throughout the site. Alkali sacaton was prevalent where salt spots occurred in depressions. Blue grama and buffalograss were the most common shortgrasses. Characteristic forbs found on the site include Engelmann daisy, dotted gayfeather, catclaw sensitivebriar, heath aster, western ragweed, and Louisiana sagewort. It is estimated that the Midgrass Prairie Plant Community produced from 1500 to 3000 pounds of biomass annually and that grasses produced as much as 95 percent of the annual production.

The Mixed-grass Prairie Community (1.2) is a mixed midgrass and shortgrass dominated grassland being encroached by indigenous or invading woody species that had been held at low densities by repeated fires and competition from a vigorous grass component. The preferred midgrasses, such as sideoats grama and vine-mesquite, are being replaced by the more grazing resistant grasses such as buffalograss, blue grama and Texas wintergrass. Numerous brushy species, including mesquite and pricklypear, are encroaching because overgrazing by livestock has reduced grass cover, exposed more soil and reduced fine fuel for fire. Mesquite is generally less than three feet tall and still subject to suppression by fire. The woody canopy varies between 5 and 15 percent depending on impact of grazing on herbaceous species, time since burned and availability of invading species. Forage production in the Mixed-grass Prairie Community (1.2) is still predominantly grass. Annual production has declined and averages from 1000 to 2,500 pounds per acre.

Submodel

Description

Shortgrass/Mixed-brush Community (2.1) has a 15 to 35 percent woody plant canopy of mixed-brush. Mesquite is the dominant woody species while pricklypear and lotebush are the most common smaller shrubs. Mesquite is an early increaser throughout the MLRA. Typically, pricklypear, lotebush and tasajillo have also increased in density and frequency in this vegetation type. Remnants of historic climax grasses and forbs and unpalatable invaders occupy the interspaces between trees and shrubs. Cool-season grasses such as Texas wintergrass and annual brome can be found under and around woody plants. Characteristic forbs are heath aster, western ragweed, silverleaf nightshade and annual broomweed. Total plant production declines somewhat, being approximately 900 to 2,300 pounds per acre.

The Mixed-brush/Shortgrass/Annuals Community is a dense shrubland dominated by mesquite. Common understory shrubs are pricklypear, lotebush, and pricklypear. With time and continued heavy grazing and no brush control, the mesquite will become tree-like and approach 75 percent or more canopy cover. Texas wintergrass, shortgrasses and low quality annual and perennial forbs are found under and around the woody species. Characteristic grasses are meadow and sand dropseed, hairy tridens, tumble lovegrass and three-awns. Forbs include heath aster and silverleaf nightshade. Cool-season annuals such Japanese brome and annual broomweed grow profusely during wet springs. Herbaceous plants produce less than 25 percent of the annual production. Total annual production ranges from 800 to 2200 pounds per acre.

Submodel

Description

The Claypan Prairie Ecological Site, with its productive soils, is often cultivated (3.1) and planted to crops. Technical advice as to adapted crops, cropping systems, production, and cultivation practices are available from local NRCS or Extension Service offices. When abandoned from cropping, the site should be re-vegetated with adapted native plant mixtures, which include reference community species.

Submodel