2013-04-19_REPORT - C2009087 (7)

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Total average vegetation cover for first -hits was 47.2 percent. Allowable first -hit herbaceous cover was 28.3 percent. Cover by standing dead, litter, bare soil and rock averaged 3.3, 42.7, 6.7 and 0.1 percent respectively. Average species density was 31.9 species per 100 sq. m. PRODUCTION (Table A -8) Total herbaceous production in 2012 was 456.8 pounds per acre. Native perennial cool season grasses and native perennial forbs were the biggest producers, contributing 269.4 and 123.1 pounds per acre, respectively. Three other lifeforms were present with less than 61 pounds per acre. DISCUSSION Climatic Conditions The year preceding 2011 sampling was characterized by a very wet fall and winter (precipitation in December of 2010 totaled a record 2.98 inches), continuing in early spring with a very wet April and May (Figure C -7b). June 2011 precipitation was below average with a return to above average precipitation in July 2011. The abundant cold- season precipitation created above average snowpack levels for the region. These wet months combined with a wet summer left precipitation total for the 12 months preceding sampling well above average (Figure C -8b). In general, 2011 was the wettest and coolest observed in the last 26 years. In contrast, the winter and spring preceding 2012 sampling was very dry, with precipitation at well below average (Figure C -7b). March, April, May and June of 2012 also had below average precipitation. As a result, precipitation for the 12 months preceding sampling was the second lowest in the last 26 years, with 2002 being the lowest (Figure C -8b). The first six months of 2012 were also the warmest in the last 26 years (Figure C -11). Sample Adequacy Calculations Sample adequacy of total first -hit vegetation cover was achieved in each of the reference areas as well as BRB PSCM -2 in 2012 (see below and Table C -4). In 2012, sample adequacy based on allowable herbaceous cover was also achieved in BRB PSCM -2 as well as the Sagebrush Reference Area. However, sample adequacy based on allowable herbaceous cover was not reached in the Mountain Brush Reference Area. Thus the alternative of using the upper 90% probability value of the mean was exercised.' In other words, after having established a reliable estimate of population variance having taken 18 samples in 2012, the maximum possible values of the mean (with 90% confidence) was taken to ' The concept of using the upper 90% limit for Mtn Brush Ref. cover was presented to CDRMS vegetation staff in a meeting in Denver, 3/12/12. A subsequent e-mail (4/2/12) from Jason Musick of CDRMS indicated that they could find nothing in the permit language that would preclude its use. 14