2012-06-20_PERMIT FILE - C2010089 (61)

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and smooth brorie was r 0.997 (P< 0.045) Working a id r = 0.45 (P< 0.71), respectively. the Piceance Basin of western Colorado, Biondini et al. (1986) reported species diversity was inversely correlated with the combined composition crested wheatgrass, pubescent and intermediate wheatgrass. Analysis of our data failed to confirm such a relationship. In our study, the combined cover of intermediate and crested wheatgrass produced a positive coefficient of correlation of r s 0.89 (P< 0.0001). Data presented by Parkin et. al. (1980) also indicates a positive correlation where r 3 0.883 (P< 0.075). Based partially upon studies such as Sindelar (1980) and Biondini et. al. (1986) various a state and federal regulatory agencies west have effectively banned the utilization of crested wheatgrass and smooth brome due to their perceived negative influence on species diversity. It is our opinion the findings of this study do not substantiate such an adverse relationship between these introduced species and overall plant community development as measured by the species diversity indexr �lthisresite. The findings from this study p a findings from 15 year old reclaimed spo i n this region (Parkin et. al. 1980). We our data are supportive of the findings of Terwilliger et. al. (1974) from a similar high elevation ecosystem in western Colorado wherein he reported crested wheatgrass did not appear to suppress the invasion of indigenous native species on several revegetated sites. The species which appeared to correlate best with species diversity was alfalfa. The coefficient of correlation for species diversity and alfalfa composition was determined l equal r = -0.97 (P< 0.007), To verify relationship, we tested the results from previous work in this area (Parkin et. al. 1980). The coefficient of correlation here was calculated at r = -0,995 (P< 0.06). Since previous documentation (DePuit tea and Coenenberg 1980) has shown grazing species diversity and lowers alfalfa lfaallf jow dominance in in reclaimed stands, we suggest diversity attributable to S manage�nent ed sites than be more r to the presence of introduced species or alfalfa. In 1980 and 1981, this operation attempted to gain regulatory approval to graze the area, however, because of the state regulatory interpretation, that reclaimed areas could not be grazed period, until the ninth and tenth year of the liability the area was not grazed. We suspect the reduction of species diversity is due more to the exclusion of grazing than the use of introduced species. This concept is further supported by Parkin et al. (1980) where nontopsoil spoils were dominated in diversity ty un er grazing from 1970 to progressively 980 If this information were being used to apply for bond release at the CYCC operation, the revegetation success stand for the ungrazed mountain shrub community would apply. The production standard for the area would be 886 Kg /ha for production and 64.5 percent cover. The species diversity would be 1.046, with 6 major species accounting for 64 percent of the diversity index total (Energy Fuels Corporation 1979). Based upon our production (Tables 5 and 10) and cover estimates (Tables 3 and 8), topsail is not necessary to achieve either the production or cover standards. The species diversity standard would not be attained even though an extremely diverse mixture of 36 species was planted. It is unlikely the species diversity or species richness standards could be achieved, either with or without substantial depths of topsoil. It is our opinion, based upon nine years of monitoring data, the optimum depth of respread topsoil on regraded spoil on this site for maxim ; forage production, total plant cover, overa 1 species diversity and richness is sra bbeen t10 and 20 cm. This figure parallels reconmendation of Power et. al. (1981) w o recommended 20 cm, Redente and Hargis (1985) and Halverson et. al. (1987) wherein they recommended 15 cm; and Barth (1984) who recommended 14 cm as the optimum depth of respread topsoil for microbial activity. Previous research at this site (Skaptason 1978) has documented no difference in microbial populations between raw spoil, respread topsoil and undisturbed soils Barth's estimate may be overly conservative for this site. Hydrologic research on this site (Striffler and Rhodes, 1981) has shown essentially no difference in erosion between spoil and respread topsoil, but suggests a greater depth of wetting with topsoil. Greater wetting depth might provide some advantage to topsoiiin DePuit (1984) reviewed the literature on see reserves in connection with topsoil depth and concluded most seed reserves were confined to the upper most 5 -7 cm of the profile. With regard to the inoculation of mycorrhizae, Allen soil (1984) suggested respreading 2 cm fresh topsoil onto regraded spoil or poor quality might be more advantageous towards long term reclamation than reapplication of a thick layer of biological inert stored topsoil - these recommendations and findings from our study, and considering the topsoil and spoil quality of this area, we believe there is little justification to reapply more than 10 to 20 cm of topsoil onto regraded spoil. We believe the most notable finding from this evaluation is the response of vegetation characteristics to respread topsoil is extremely dynamitic over time. Since existing regulations require bond release for reclaimed area s nibe obtained from data collected during years based and ten following seeding, it appears, upon our findings and examination of all long