Red Clay (South) 23-30" PZ

Description

The Mixed-grass Prairie Community (1.1) is the interpretive plant community for the Shallow Clay Ecological Site. It was open grassland with a mixture of midgrasses and shortgrasses, some tallgrasses and forbs along with scattered shrubs. Feather and black dalea, pricklypear, ephedra, lotebush and agarito were widely scattered in protected areas, but probably made up less than five percent of the plant canopy. Sideoats grama was the dominant or co-dominant grass throughout the site. The most common shortgrasses were buffalograss, blue grama and curly mesquite. Forbs include dotted gayfeather, western ragweed, American basketflower and catclaw sensitivebriar. Productivity of the site is around 1,000 to 3,000 pounds/acre of biomass annually.

The Midgrass Community (1.2) is a midgrass dominated grassland being encroached by indigenous or invading woody species that had been previously held at low densities by repeated fires and competition from a vigorous grass component. The preferred tallgrasses and midgrasses are being replaced by the more grazing resistant midgrasses and shortgrasses. Numerous brushy species, including juniper and mesquite, are invading the site. In this plant community type, the increasing woody species are generally less than four feet tall and the woody canopy vary between 5 and 15 percent. Typically, mesquite and/or juniper invade from adjacent sites and indigenous species increase in density. Important grasses are sideoats grama, little bluestem, cane or silver bluestem, Arizona cottontop, Texas wintergrass and Canada wildrye. They give way to less palatable and more grazing resistant shortgrasses. Annual primary production ranges from 800 to 2,500 pounds per acre.

Submodel

Description

The Shortgrass/Mixed-brush Community (2.1) supports a 15 to 25% percent woody plant canopy of mixed-brush species. Mesquite is often the dominant overstory and pricklypear and lotebush the most common shrubs. Plant composition and production shifts toward a grazing resistant shortgrass and woody component as selective grazing reduces the preferred species. All, except the more palatable woody species, increase in size and density. Many of the climax shrubs are present. Remnants of climax grasses, such as little bluestem, sideoats grama, buffalograss 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.

Mesquite and/or redberry juniper dominate the Mixed-brush/Shortgrass/Annuals Community (2.2), which is a mixed-brush shrubland. Common understory shrubs are pricklypear, agarito, dalea, lotebush, yucca and tasajillo. With continued heavy grazing and no brush control, the trees and shrubs can approach 60 percent ground cover. Shortgrasses and low quality annual and perennial forbs occupy the woody plant interspaces. Texas wintergrass and cool-season annuals, particularly annual brome and annual broomweed, are found in and around tree/shrub cover. The cool-season species flourish following a wet fall and winter. Grasses and forbs make up 25 percent or less of the annual herbage production. Forbs are also commonly found in this community.

Submodel