2020-03-24_PERMIT FILE - C1981019A (2)

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RULE 2 PERMITS species are designated noxious weeds (`B" List taxa on the Colorado State List) with several others (e.g., cheatgrass) classified as invasive weed species. Identified noxious weeds include musk thistle (Carduus nutans), Canada thistle (Cirsium arvense), and houndstongue (Cynoglossum ofcinale). Specific - Detailed vegetation mapping and quantitative data collection occurred by performing baseline vegetation surveys (or supplemental surveys) within the study area of the Lower Wilson Mine Area. Emphasis was placed on the disturbed area for quantitative efforts. Six native vegetation communities and two land use types were identified from this area as follows: Mountain Shrub Sagebrush Aspen Woodland Grassland Juniper Scrub Bottomland Cropland (land use) Stock tank (land use) As previously discussed, only the grassland community was completely sampled with baseline surveys (ground cover, production, and woody plant density) while the remaining communities received supplemental ground cover sampling. In this regard, grassland was the only vegetation type requiring establishment of a reference area to facilitate development of performance criteria. Rationale for this strategy was that existing data and reference areas for Mountain Shrub, Sagebrush, and Aspen communities would be sufficient for this permit revision effort (see existing Colowyo permit and Table 2.04.10-10). As previously indicated, the juxtaposition / distribution of Study Area vegetation communities, sample collection locations, and reference areas are presented on Map 4B. A summary of the average ground cover based on 2005 data is presented on Table 2.04.10-11 and Figure 2.04.10-3. Similarly, a summary of the relative cover (composition) based on 2005 data is presented on Table 2.04.10-12 and Figure 2.04.10-4. Raw ground cover and production data for the grassland community and reference areas are presented on Tables 2.04.10-13 through 2.04.10-18 with a summary of production data presented on Table 2.04.10-19 and Figure 2.04.10-5. The raw data for grassland woody plant density are presented on Table 2.04.10-20 and Figure 2.04.10-6. The principal parameters for the t-test of the means utilized to validate the grassland reference areas are presented on Table 2.04.10-21. Finally, the raw ground cover data collected as supplementary information for the five non -grassland communities are presented on Tables 2.04.10-22 through 2.04.10-26. Grassland - As indicated on Map 413, the grassland community within the Study Area occupies 16.97 acres and occurs in six locations. The two grassland reference sites are located against the west Study Area boundary (1.23 acres) and on the ridgeline (1.01 acres). A total of 31 species were observed within the grassland community while the lower and upper reference areas exhibited 29 and 42 taxa, respectively. Average ground cover of vegetation within the study area was 69.93% with 0% rock, 21.07% litter, and 9.0% bare ground exposure. Dominant species included: bluegrass (Poa agasizensis), thickspike wheatgrass (Agropyron dasystachyum), Western wheatgrass (Agropyron smithii), tailcup lupine (Lupinus caudatus), slender wheatgrass (Agropyron trachycaulum), groundsmoke (Gayophytum ramosissimum), and mountain big sagebrush (Artemisia tridentata ssp. vaseyana). The number of perennial herbaceous species exhibiting between 3% and 50% relative cover (composition) was determined to be 4 grasses and 1 forb. Current annual herbaceous production within the Study Area's grassland community was determined to be 1,754 pounds per acre with 83% due to perennial grasses and 15% due to perennial forbs. The remaining 2% was due to annual species. Woody plant density based on the total count of plants within a 0.46 -acre macroplot was 509 plants per acre with dominance by mountain big sagebrush and rubber rabbitbrush (Chrysothamnus nauseosus). South Taylor/Lower Wilson — Rule 2, Page 52 Revision Date: 4/7/17 Revision No.: RN -07