2008-03-13_REPORT - C1981019 (2)

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2.4 Summary by Area • 2.4.1 East Pit Tables 4 and 5 exhibit the average cover and composition of vegetation found on the six East Pit • rowing seasons) has progressed well toward meeting bond Unit EP036 (7 2007 d i l t g . n ua e units eva release criteria with the exception of woody. plant density. Perennials cover (49.6%) and production 7 pounds per acre) easily pass comparisons with the reference areas. Similarly, the present 178 (1 . , diversity of perennial grasses (5) meets the standard of 3 perennial gr sses. With regard to perennial forbs, EP036 (1) meets the standard of 1 perennial forb with between 3% and 50% relative cover. Woody plant density in EP036 is slightly low at 694 woody plants per acre (in comparison to the present standard of 90% of 1,000 woody stems per acre). See Appendix AA 'Section 6.3 for a discussion on options and recommendations with regard to woody plant density. Although annual bromes currently represent an average of 15.3% cover, any pockets or patches of this invasive weed should be monitored to gauge if they are expanding or shrinking. If monitoring reveals expansion, use of the herbicide Plateau is recommended. i Units EP039, EP040, EP041, and EP044 are exhibiting mixed results after four growing seasons. Annual bromes exhibit strong populations in all of the units occupying an average of 44.6% of the vegetative composition. However, perennial grasses and forbs are still present throughout these units. It is recommended that EP039, EP041 and EP044 be sprayed with the herbicide Plateau to help control the annual bromes and release the perennials. Spot reseeding may tie necessary in isolated patches without remnant populations of perennial vegetation. Woody plant ~~density in units EP039, EP040, EP041, and EP044 are also very low at 0, 8, 3, and 0 woody plants per acre, respectively (in comparison to the present standard of 90% of 1,000 woody stems per acre). See~Appendix AA -Section 6.3 fora • discussion on options and recommendations with regard to woody plant density. Unit EP046 was seeded in 2005 and therefore, was undergoing only its second growing season in 2007. Annual brome populations exhibit a stronghold in this unit with; 36% of vegetative composition. • However, perennial grasses, forbs, and shrubs are still present throughout this unit with an average • cover of 23.8%. Woody plant density in unit EP046 is very low with 43.2 woody plants per acre. • Monitoring this unit in 2009 will be informative and will indicate progress toward meeting bond release • criteria. i .r • Rio Tinto Energy America/Colowyo Mine Page 28 i Revegetation Monitoring - 2007 i ~1 U