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3.0 VEGETATION 3.1 Local Ecology The project Site is charncterized by extensive, flat-lying river terraces approximately 200 feet above the current level 16,080 feet) of the Roaring Fork River; by a portion of the existing river floodplain; by river islands; end by a river terrace intermediate in elevation 16,100 feetl between the oldest end highest terrace and The current floodplain. Steep slopes occur between terraces and the floodplain and on the 7,200 foot elevation mountain adjoining the project site to the southwest. Elevations at the project site range from a high of 6,560 near The Crystal River Ranch buildings to a low of 6,080 along the river. The mean annual temperature for the Brea (Glenwood Springs, Colorado) was 47.6oF in 1978. Winters are cold and the ground generally is snow Covered. The growing season is short, perhaps ranging from 60 to 120 days. Precipitation is estimated to range from 14 to 18 inches. Glenwood Springs, et a lower elevation (5,823 feet) receives a yearly overage of 16.53 inches of precipitation. Moisture generally occurs in the spring months. The project site is in the Pinyon-Juniper Woodland biome as described by Shelford (19631 and as mapped by Kuchler (19751 and the U.S. Forest Service 11967). However, topographic variability combined with soil differences and moisture gradients have produced numerous distinct plant communities at the project site. The native vegetation types of the project site have been altered by farming and ranching activities. The sagebrush vegetation type on river terraces has been plowed and seeded to hay grasses and fortis and is watered by en intricate system of irrigation ditches. The vegetation cover, composi- tion, and production of the surrounding native vegetation communities has been greatly altered by the intensive grazing of livestock for perhaps as much as 100 years. Species sensitive to grazing have disappeared and been replaced by numerous undesirable species. Total vegetation cover has decreased resulting in a drastic reduction in community production. i A Pinyon-Juniper Woodland liaalu+.~ edul.~~-'froupe~trz.~ ~copu,Conwal occurs on Steep, rocky, and shallow soils on the mountain to the southwest of the project site, in gulleys of river terraces, and on the Slopes between river terraces. Prior to farming a Big Sagebrush Shrubland vegetation type iA~#emi~ia Lcidon- }nln) dominated the deep soils of the river terraces. Today, big sagebrush is restricted to colluvial soil areas et The base of the mountainous slopes and to portions of the river terraces not being farmed. A Rubber Rabbitbrush Shrubland vegetation type (Ch~ao#harrwt~ rtattieonu.~l occurs in a linear Strip along the Sweet Jessup irrigation canal. A smell native grass meadow occurs on that portion of the current river floodplain cleared of woody riparian vegetation. Riparian vegetation is restricted to slopes surrounding the river and to stream islands. A portion of the project site has ranch • -7-