Loamy Upland 8-12" p.z.

Description

State 1. Native Grass-Shrub State has two Community Phases that fluctuate with dry/wet weather cycling. The Reference Plant Community (CP1.1) is a an open community of perennial grasses and desert shrubs and cacti. Annual forbs and grasses, of both the winter and summer wet seasons, are very important in the plant community in their respective (wet) seasons. Tobosa, black grama and bush muhly are the dominant perennial grasses, with lesser amounts of perennial mid-grasses such as threeawns and dropseeds. The cover of some shallow rooted grass species, like curly mesquite and Rothrock grama fluctuate widely from wet to dry years. Climate fluctuations, cycling of wet winters, favors shrub growth thus allowing the shrub dominance in CP1.1; extended drought will contract both perennial grass and shrub canopy covers, transitioning the community phase to CP1.2. Natural fire may occasionally occur in this LRU but is not thought to have recurred with a frequency to shape this plant community.

Submodel

Description

State 2, Non-Native Grass State, predominantly cycles between two Community Phases: large shrub-annual forbs (CP2.2) / large shrub-Lehmann lovegrass (CP2.3). Community Phase 2.1 persists for about 10 years after brush management before shrub dominance resumes. Restoration from State 3, prescribed grazing without brush management, will result in CP 2.2. The prevalence of Lehamnn lovegrass within the soil seedbank no longer requires range seeding. Once a soil seedbank is established, LL persists in the plant community while its basal cover varies with climate, elevation, and depth of surface soil over argillic. Lehmann lovegrass only dominates the entire plant community in CP 2.1, after brush management and seeding, but it will dominate the herbaceous layer of the plant community once established. Lehmann lovegrass production does not exceed 400# / ac during Non-Native lovegrass cycles.

Submodel

Description

State 3, Large Shrubs-Annuals, comes about after years of heavy grazing. Suffrutescent grasses are confined to tightly protected areas within shrub and cactus canopies leaving large bare areas as inter-shrub spaces.

Submodel

Description

State 4, Large Shrubs, Eroded, has active, accelerated erosion. This state occurs where mesquite canopy is heavy (15-25%) and the interaction of drought and continuous grazing has resulted in severe sheet, rill and, in some cases, gully erosion on the site.
These areas are usually near historic watering locations and are characterized by soil compaction due to trailing and heavy livestock traffic.

Submodel