2011-12-22_PERMIT FILE - X201123500 (2)

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Habitat Management, Inc. Vegetation and Wildlife Baseline Survey Report Linc Energy Little Snake River Project Perennial herbaceous components contribute greater than 25% vegetative cover and consist mostly of rhizomatous and bunch -form graminoids, with a diversity of perennial forbs. The dominant graminoid in this system is western wheatgrass (Pascopyrum smithii). Other species include Indian ricegrass (Achnatherum hyrenoides), blue grama (Bouteloua gracilis), Sandberg's bluegrass (Poa secunda), or bluebunch wheatgrass (Pseudoroegneria spicata). Dryland rhizomatous sedges such as threadleaf sedge (Carex frlifolia) and needleleaf sedge (Carex duriuscula) are very common and important in the eastern distribution of this system in Colorado. Within this type, cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and other invasive weeds can be abundant where there is frequent disturbance. Cheatgrass is typically not as abundant as Japanese brome in the Inter - mountain West, possibly due to a colder climate. Common forbs include Hood's phlox (Phlox hoodii), sandwort (Arenaria species), prickly pear (Opuntia species), scarlet globemallow (Sphaeralcea coccinea), purple prairie clover (Dalea purpurea), gayfeather (Liatris punctata), and milkvetch (Astragalus species). The natural fire regime of this ecological system maintains a patchy distribution of shrubs, so the general aspect of the vegetation is a steppe grassland. Shrubs will increase following fire suppression. Where fire frequency has allowed for shifts to a native grassland condition, the area would be classified as a Semi -Desert Grassland. Several state and transition models describe plant succession in sagebrush steppe plant communities. In these models, both the Grassland community (the product of disturbance [fire]) and the Sagebrush Steppe community are identified as a single "state" because the change from the grassland plant community to the sagebrush /grass plant community does not entail crossing an "ecological threshold." Sagebrush will advance on the grassland plant community with time alone. Grazing management can affect the speed of the progression because pressure on the herbaceous community can create more sagebrush germination sites. However, independent of grazing management, sagebrush canopy cover will eventually advance to a level commensurate with climatic conditions (somewhere less than 35 %). This canopy cover develops independent of the health of the grassland plant community and once the sagebrush canopy reaches its potential (the site becomes fully occupied), the herbaceous niches become limited. Grazing does not hinder young sagebrush plants from growing and occupying more space on the landscape. Consequently, because these two communities are transitional and they do not persist in the absence of disturbance, they are not identified as independent "states." As with the Semi- Desert Grassland, the relative composition of the common grasses is primarily dependent upon past grazing intensity and the cover of sagebrush, which is primarily dependent upon the elapsed time since the last range fire. In summary, the Big Sagebrush Shrub Steppe community is simply a Semi - Desert Grassland plant community with an overstory of sagebrush. Page 4 December 2011