Loamy 19-26" PZ

Description

Little bluestem occupies favorable micro-sites and is locally dominant in the Midgrass Prairie Community (1.1). Sideoats grama is the dominant or co-dominant grass throughout the site. Also occurring on the site, but in smaller amounts, are cane and silver bluestems, vine mesquite, black grama, plains bristlegrass, and Texas wintergrass. Blue grama and buffalograss are the most common shortgrasses. The hackberry trees are widely scattered in protected areas, but probably make up less than one percent of the plant canopy. Littleleaf sumac, yucca, dalea, fourwing saltbush, wolfberry, and catclaw acacia are typical, but infrequent, shrubs. A few of the common forbs found on the site include prairie clover, dotted gayfeather, wild alfalfa, catclaw sensitivebriar, and bundleflower.

The Midgrass/Shortgrass Community (1.2) is a 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 are being replaced by the more grazing resistant midgrasses and shortgrasses. 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. In this plant community type, the increasing woody species are generally less than three feet tall and still subject to control by fire and improved grazing management. The woody canopy varies between 5 and 15 percent.

Submodel

Description

The Shortgrass/Mixed-Brush Community (2.1) supports a 15% or greater woody plant canopy of mixed-brush with mesquite often the dominant overstory and pricklypear or broom snakeweed the most common shrubs. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs. All, except the more palatable woody species, have increased in size and density. Mesquite is an early increaser throughout the MLRA although it usually does not reach as high a density on this site as on other loamy soils. Many of the climax shrubs are present. Typically, pricklypear, lotebush (Ziziphus obtusifolia), littleleaf sumac and broom snakeweed are common in this plant type.

The Mixed-Brush/Shortgrass Community (2.2) is dominated by a dense shrubland of mesquite. Common understory shrubs are pricklypear, broom snakeweed, evergreen sumac, lotebush, yucca and wolfberry. With continued heavy grazing and no brush control, the trees and shrubs can approach 70 percent ground cover. Shortgrasses and low quality annual and perennial forbs occupy the woody plant interspaces. Characteristic grasses are buffalograss, sand dropseed and three-awns. Texas wintergrass and cool-season annuals are found in and around tree/shrub cover. Grasses and forbs make up 25 percent or less of the annual herbage production.

Submodel