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4.4 SPECIES COMPOSITION <br />• The Colorado Division of Reclamation, Mining and Safety considers species composition of <br />the revegetated and reclaimed azeas to be an indicator of successful vegetation establishment <br />and a diverse vegetation community. The species composition standazd for final bond release <br />at the Keenesburg Mine was revised in 2005 by Technical Revision 37 to better reflect the <br />number and seasonality of species in the pre-mining and post-mining vegetation <br />communities. The species composition standard now requires that there be at least four <br />perennial species, of which three are warm season grasses and one a cool season grass. No <br />one component of the above four species should comprise greater than 40% relative <br />importance nor less than 3% relative importance. Relative importance will be measured by <br />calculating relative cover of the revegetation species. Vegetation species which may be used <br />in the calculation of species composition may be any plant species not defined as a noxious <br />or prohibited plant species, and may be native or introduced. <br />A comparison of the 2007 species composition data with the revegetation success standazd <br />reveals that the 1998 reseeded or interseeded azeas met the final bond release species <br />composition success standazd this season with three qualifying warm season graminoids and <br />one cool season graminoid. The 1999 reclamation azeas had adequate numbers of perennial <br />species and cool season grasses, but lacked one warm season grass. Interestingly, <br />Calamovilfa longifolia was disqualified in the 1999 reclamation areas as it provided too <br />much relative cover (41.98%). The 2000 reclamation azeas lacked one warm season and one <br />cool season grass species. Three warm season grass species and one cool season grass were <br />lacking in the 2002 reclamation areas. The 2003 reclamation azeas exceeded the number of <br />qualifying cool season grass species (2), but lacked two qualifying warm season grasses. <br />4.5 COMPARISON OF VEGETATION COMMUNITIES: 1994-2007 <br />Direct comparison of the 2007 monitoring data for the areas sampled with that of previous <br />years to evaluate long-term trends in vegetation communities can only be undertaken for a <br />moderate time period (four to eight years), and for only two of the azeas sampled (the 1998 <br />reseeded and interseeded areas and the 1999 reclamation areas). <br />Table 10 presents comparisons of relative cover for encountered plant species within the <br />1998 reseeded and interseeded azeas and the 1999, 2000, 2002, and 2003 reclamation areas <br />for the years 1999-2007. Within the table aze several interesting trends revealing changes in <br />species composition at the reclaimed azeas. These trends are likely attributable to the <br />ambient precipitation regime, vegetation community development, and management of the <br />azeas and adjacent property. <br />4.5.1 1998 Reseeded or Interseeded Areas <br />Quantitative sampling has been undertaken in these areas for the past nine growing seasons. <br />During this time thirty-six species have been encountered. Of the species encountered, five <br />have been present all years, and four additional species have been present in eight of the past <br />nine seasons. The species present in all nine seasons include two native perennial warm <br />season grasses (Bouteloua gracilis and Calamovilfa longifolia), one introduced annual grass <br />Coors Energy Comparry Keenesburg Mine Page 22 <br />2007 Revegetation Monitoring Report <br />