Lakebed 23-30" PZ

Description

The interpretive plant community for the Lakebed occurs when the moisture regime of the Lakebed Site is relatively dry because inundation is infrequent or occasional; the reference plant communtiy is a Mixed-grass Community (1.1). This situation normally occurs in the smaller lakebeds and in larger, deeper lakes during extended dry cycles. Vine-mesquite, buffalograss, western wheatgrass, knotgrass, blue grama and white tridens are the primary grasses in most of the grass-dominated lakebeds. Sedges and spike rushes are generally present in small amounts. Common forbs are frogfruit, arrowhead, evening primrose, knotweed and plains coreopsis, especially during wet cycles. Total annual yields ranged from 1000 pounds in dry years to as much as 4,000 pounds in wetter years.

The Degraded Shortgrass/ Annuals Community is composed of less palatable, or less grazing resistant, shortgrasses, grass-likes and forbs. Sedges, rushes and buffalograss increase in composition along with annuals such as little barley, barnyard grass, and six-weeks fescue. Invading forbs include knotweed, kochia, primrose, silverleaf nightshade and blueweed sunflower.

Submodel

Description

The Mixed-Hydrophytes Community are frequently ponded or inundated for long periods of time. It can occur as the result of an extended wet cycle. Plants such as arrowhead, rushes, spike rushes, flatsedges, knotweed, smartweed and annuals dominate the composition and production. Vine-mesquite and buffalograss are often present around the edges of the ponded areas, but absent where water stands for long periods. Larger lakebeds support the greatest diversity of vegetation. Several mesic forbs such as sawtooth frogfruit, kochia, bur ragweed, slimleaf goosefoot and spiny aster can be expected. Total annual herbage production ranges from 1,500 pounds in dry years to over 4,500 pounds under good moisture conditions. Most of the production is by hydrophytes, many of them grass-like species.

The Degraded Hydrophytes/Annuals Community (2.2) is the result of long-term overgrazing of the Mixed-Hydrophytes Community (2.1) by livestock. Selective grazing reduces the more palatable, or less grazing resistant shortgrasses, grass-likes and forbs. Flatsedges, spikerushes and rushes increase in composition along with sawtooth frogfruit, smartweed, knotweed, kochia, primrose, silverleaf nightshade and arrowhead. Annuals grasses such as little barley, barnyard grass, and six-weeks fescue may occur seasonally along the outer edges. Considerable bare ground occurs in denuded areas and along the edges of the ponded areas. Drought conditions shrink the ponded area negatively affecting the hygrophilous species allowing egress of annual grasses and forbs.

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