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3.0 RESULTS AND DISCUSSION <br /> 3.1 ENVIRONMENTAL CHARACTERISTICS <br /> The climate of th area is arid to semi-arid, with a precipitation <br /> at Palisade of about inches a year. The project area, however, is <br /> somewhat higher in elevation and hence may receive an additional few <br /> inches of precipitatio Iper year. See Table 1. Precipitation at <br /> Palisade is distributeJ somewhat uniformly throughout the year, with a <br /> slight peak during Aug ,st, September, and October. The 1981 growing <br /> season received more jisture than an average year. Likewise, tempera- <br /> tures were considerabl, higher than the average expected. The growing <br /> season is relatively 11 hg, extending from the beginning of April through <br /> the end of October, 20 days. However, the growing season in Coal <br /> Canyon, especially on northeast-facing slopes, may be slightly shorter <br /> because of the higher Ititude and aspect. <br /> The study area oc:urs in a region mapped as pinyon-juniper by <br /> Kuchler (1966) and Shelford (1963) . These mappings accurately depict <br /> the regional climax ve etation types but are not of sufficient detail <br /> to reflect vegetation hanges related to exposure and substrate <br /> variations. <br /> The ephemeral stream draining the canyon supports a very narrow <br /> riparian shrubland veg Cation type with scattered plains cottonwoods <br /> Pvpu.tu,j detto4deJ and i g sagebrush kz-tem1,j<a tA4deata.ta. Sma I I , <br /> isolated areas of a sal ina wildrye grassland & uA 4atinuj vegetation <br /> type occur along the riparian shrubland at the foot of the northeast- <br /> facing slopes. These rtheast-facing slopes are characterized by an <br /> expansive Pinyjon/Junip Woodland NtLu4 eduti4/6unipelzuj ojteojperuna. <br /> Small islands of black sagebrush 4,,ztem1Z*,j4a nova occur dispersed amid the <br /> Pinyon/Juniper Woodland. On the southeast aspect of these same slopes <br /> sma l I linear islands of a Shadsca 1 e Shrub I and Atizlplex con, e zti, o.La <br /> predominate. This sam vegetation is expansive on the upper reaches of <br /> the southwest-facing slopes. The lower elevation of the southwest-facing <br /> slopes are distinguished by a Sagebrush/Cheatgrass Shrubland, the only <br /> vegetation type to be affected by mining activities. Figure 1 illus- <br /> trates the mosaic of vegetation types within the permit area, while <br /> Table 2 identifies the acreage of each of the communities within this <br /> area. <br /> The study area is nderlain by various sedimentary rock strata of <br /> the Mesa Verde group. hese strata are dipping steeply to the northeast . <br /> The northeast-facing slopes, covered by mostly Pinyon/Juniper Woodland <br /> and Black Sagebrush Shr bland vegetation, is underlain by the Mount <br /> Garfield formation sand tones and shales and Sego formation sandstones. <br /> These strata cap the Ma cos shale which form the Book Cliffs (or <br /> Palisades) above the town of Palisade a short distance south of the study <br /> area. The drainage thr ugh Coal Canyon follows more or less along the <br /> contact between the Sego sandstone and the next higher stratum, the <br /> -6- <br />