Sandy Plains

Description

The Tall/Midgrass Community (1.1) is the interpretive/diagnostic/reference plant community for the Sandy Plains Ecological Site. Sand Shinnery/Havard oak mottes were widely scattered in microsites protected from frequent fire and made up less than ten percent of the plant canopy. Sand sagebrush, broom snakeweed and yucca were also present, but infrequent. Little and sand bluestem along with mesa and giant dropseeds are the dominant or co-dominant grasses throughout the site depending on variations in soils and water relations. Also occurring on the site, but in smaller amounts, were midgrasses such as sideoats grama, Plains Lovegrass, Hairy grama, Fall witchgrass, Sand Paspalum and three-awns provided most of the annual production. Common forbs found on the site include prairie clover, dotted gayfeather, wild alfalfa, catclaw sensitivebriar and bundleflower. The Tall-Midgrass Grassland community produced from 1,600 to 3,500 pounds of biomass annually.
The Midgrass/Shrubs Community (1.2) is the result of the interaction of the reduction in frequency of fires and exacerbated by severe droughts. The reduction in vegetative structure and ground cover resulting from reduced fire frequency allows the shrubs a competitive advantage of a vast and persistent root system and to begin to hoard more site nutrients, processes and space to themselves. Sand Shinnery/Havard oak, honey mesquite, broom snakeweed and sand sagebrush increase in density and cover, varying from 10 to 20 percent canopy cover. Sand dropseed, hooded windmillgrass and perennial three-awns begin replacing the more palatable tall and midgrasses found in the reference community. Most forbs such as gaura, groundsels, palofoxia and wild buckwheat persist in the Midgrass/Shrubs Community. Annual yield ranges from 1,000 to 2,300 pounds.

Submodel

Description

The Mixed Shortgrass/Shrub Community (2.1) supports a 20 to 45 percent woody composition as measured by canopy cover. Honey mesquite, Sand Shinnery/Havard oak, sand sagebrush, broom snakeweed and yucca being the most common shrubs. This plant type is the result of selective grazing by livestock and the differential response of plants to defoliation over a long period of time. There is a continued decline in diversity of the grassland component and an increase in woody species and unpalatable forbs.

The Shrub/Shortgrass/Annuals Community (2.2) is the result of many years of inappropriate grazing, lack of periodic fires and little brush management. Sand Shinnery/Havard oak and honey mesquite dominate the Shrub/Shortgrass/Annuals Community, which is essentially a shrubland. Under extreme conditions of grazing and drought, the site deteriorates to active dunes and blowouts. Common understory shrubs are broom snakeweed, yucca and sand sagebrush. With continued inappropriate grazing and no brush control, the shrubs can approach 70 percent or more of the composition of the site as measured by canopy. Short-grasses and low quality annual and perennial forbs occupy woody plant interspaces.

Submodel