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• 3.0 RESULTS AND DISCUSSION <br />3.1 REGIONAL ECOLOGICAL CHARACTERISTICS <br />The climate of the region is semi-arid, with an average precipitation of <br />18.6 inches per year (Table 11. Precipitation is scattered relatively uniformly <br />throughout the year, with a slight decline in May and June. Average monthly <br />temperatures range from about 26°F in January to 68°F in July, with an average <br />frost-free season of 4-5 months from May to September. <br />There are no permanent streams in the permit area, although the Animas <br />River borders its western edge. Topographic features vary from ridgetops <br />and very steep hillsides to relatively flat old stream surfaces. Substrates <br />vary from bare sandstone and shallow soils over sandstone to deep alluvium <br />left by the Animas River when its bed was a few hundred feet higher than <br />present. The elevation ranges from 6,500 ft to 7,280 ft. <br />Historically, the vegetation of the region has been mapped as pinyon- <br />juniper woodland IKiichler 1966, Shelford 1963). This broad classification <br />reflects the most prominent vegetational feature of the permit area. <br />3.2 VEGETATION TYPE DESCRIPTIONS <br />• The permit area is characterized by two natural vegetation types--a <br />Pinyon-Juniper Woodland and a Mountain Shrubland; old field sites, where <br />oakbrush has been burned and cleared; and cultivated wheat fields. In addition, <br />the Pinyon-Juniper Woodland includes a phase occurring on bare sandstone and <br />extremely shallow soils. This phase of Pinyon-Juniper Woodland, which was <br />sampled separately, is referred to here as Pinyon-Juniper Caprock. <br />3.2.1 Mountain Shrubland <br />The Mountain Shrubland vegetation type occurs primarily on the <br />western exposures of steep slopes, along drainages, and in small scattered <br />patches throughout the area wherever soils are somewhat deeper. Total affected <br />area of the vegetation type is 24.5 acres (Table 21. The dominant species is <br />Gambel oak I~uertcu~ gamGe,liil, which often occurs in large, extremely dense <br />patches with sparse herbaceous understories. Numerous additional species of <br />shrubs are scattered throughout this vegetation type. The Mountain Shrubland <br />vegetation type interphases with Pinyon-Juniper Woodland. <br />Cover <br />Total absolute vegetation cover in the Mountain Shrubland averages <br />78.0 percent. Bare soil is only 4.9 percent, litter cover is 16.3 percent, <br />and rock cover is low at 0.8 percent. Absolute cover by lifeform is as follows: <br />shrubs--65.5 percent, perennial graminoids--5.3 percent, trees--4.6 percent, <br />perennial (orbs--2.3 percent, annual fortis--0.3 percent, and succulents--0.1 <br />percent (Table 3). <br />-8- <br />