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ERO Resources <br />trees. Arnold (1964) and Johnson (1980) reinforce these findings. <br />• Arnold's findings show that western wheatgrass (Aarapvran gmjtij) is <br />affected to a lesser degree than other perennial grasses. Jameson also <br />reports (19701 that juniper roots compete effectively with grasses, such <br />as blue gramagrass (8putal2ua gracilis) and galleta (Hilaria jamenit). On <br />the permit area, the presence but infrequency of both these grasses <br />suggests this and allelochemical effects have reduced the abundance and <br />distribution of these species. Clary and Jameson (1981) report forage <br />increased from 46 to 73% after removal of the overstory. <br />Tueller and Clark (1975) report on the other ecological effects created by <br />juniper. These authors write that individual woodland trees inhibit both <br />light and moisture interception at the surface, suggesting that <br />approximately 40% of the effective rainfall and 80% of the light are <br />intercepted by the canopy. <br />Costello (1944) reports on conditions that are indicative of increasing or <br />decreasing aspects of the sagebrush and juniper woodland communities. <br />• Costello states that declining and unsatisfactory conditions in the <br />sagebrush types are indicated when the important grasses, such as blue <br />gramagrass, western wheatgrass, fescue (Festuca spp.) and needle -and - <br />thread (Stipa comata), survive only under clumps of sagebrush and weedy <br />species become predominant. Young et al. (1979) further state that <br />wildfire or other disturbance that removes the shrub overstory will result <br />in complete invasion by weedy species, particularly cheatgrass. Weedy <br />species listed include aster IMachaeranthera linearis), saniwort (ACSAdLia <br />eantwoodiea), knotweed IEriogon,m corvmbasum) and fleabane daisy (Friyeron <br />spp.). With increasing deterioration, the larger weedy forbs decline. <br />Subsequently sheet and gully erosion also may result in areas of barren <br />ground. <br />The presence of blue gramagrass in woodlands is an indicator of good range <br />conditions, according to Costello. The absence or infrequence of this <br />grass is an indicator of decline. The presence of squirreltail grass <br />(Sitanion hvetrix) in these areas is also an indicator of general decline, <br />II.F-15 <br />