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grasses, and one cool season grass. Forb presence and numbers within the reference azea <br />aze directly related to precipitation amounts. <br />• During this growing season, the five core species comprised 85.7 percent of the total <br />relative cover of all species in the reference azea. Of these species, the perennial <br />graminoid warm season species increased slightly to significantly in relative cover this <br />season, while the perennial cool season grass decreased slightly, and the woody shrub <br />relative cover decreased. This observation appeazs to confum the relationship between <br />precipitation and species representation. The native warm season perennial graminoids <br />appeaz to increase in relative cover under lower precipitation or adverse conditions while <br />the cool season graminoids decrease (note the exception below). <br />Responses of the dominant species within the reference area have been vaned. <br />Andropogon hallii has maintained a constant significant presence within the reference area <br />since 1994, though the cover of this species does not appeaz directly correlated with <br />precipitation. Bouteloua gracilis cover in the reference area appears inversely related to <br />precipitation amount, with the greatest relative cover coming during dry yeazs (note the <br />366% increase from 2001). This may be related to a competitive effect originating with <br />the small size of this species, wherein Bouteloua thrives when cover of lazger species is <br />reduced during dry yeazs. Calamovilfa longifolia, though a warm season grass, shows <br />greater relative cover during average and wet yeazs in the reference azea. To achieve full <br />growth, Calamovilfa appeazs to require more moisture and a longer overall favorable <br />growing season. Stipa viridula, though a cool season grass, responds in the opposite <br />rnazmer of Calamovilfa, with highest relative cover values during normal and dry years. <br />• Artemisia f:lifolia continues to maintain a relatively constant presence in the reference <br />azea as shown by the relative cover values. This species appears lazgely relatively <br />unaffected by precipitation, likely due to its woody habit. <br />1995 Reclamation Areas <br />The 1995 reclamation azeas have been sampled quantitatively for the last five growing <br />seasons. A total of thirty-four species have been encountered in vegetation sampling since <br />1998. Of those species, eight were present in each year of the sampling. These species <br />included five perennial cool season grasses, two perennial warm season grasses, and one <br />annual cool season grass. <br />No one species has shown consistent yeazly increases in relative cover over the period of <br />sampling. However, several perennial species show stable contributions during the last <br />five growing seasons, including Agropyron cristatum, Agropyron dasystachyum, <br />Agropyron smithti, Bouteloua gracilis, Calamovilfa longifolia, and Oryzopsis <br />hymenoides. <br />The cool season granvnoids Agropyron dasystachyum, Bromus marginatus, and <br />Oryzopsis hymenoides decreased in relative cover this season, while Agropyron cristatum <br />and Agropyron smithii increased. Bouteloua gracilis increased in relative cover the first <br />Coors Energy Comparry Page i9 <br />2002 RevegetaUon Monitoring Report <br />