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• calculations that produced these results are given in Appendix <br />3.6.9. <br />3.6.2.2.3 Density <br />Shrub density was calculated for the sagebrush community by MRC in <br />1981 using the point-centered quarter method. Woody species with <br />a stem diameter greater than one-inch were counted during the MRC <br />field studies in 1981 while all shrubs were counted by Cook and <br />Greystone in 1982 and 1983 respectively. The reason for MRC <br />counting only the larger shrubs is that this is what was specified <br />by the State at the time and the smaller shrubs have a very low <br />probability of survival being susceptible to grazing and drought <br />and, therefore, to seasonal fluctuations. This is illustrated by <br />the fact that the density figures resulting from all three studies <br />are very similar. A density of 6819.3 shrubs/acre was calculated <br />by MRC. This compares with a density of 6639.1 shrubs/acre (14.92 <br />shrubs/9 sq.m) as determined by hook in 1982 and 6908.3 shrubs/acre <br />• calculated by Greystone Development Consultants in 1983. All of <br />these estimates, determined by three different methods, are very <br />similar (within 9~ of each other). An average shrub density for <br />the sagebrush community is 6788.9 shrubs/acre. It is proposed, <br />however, that the reclamation standard not include a parameter for <br />shrub density. Shrubs would be allowed to invade through secondary <br />succession, but bond release would be dependent on meeting the <br />cover and production standards. <br />3.6.2.2.4 Sample Adequacy <br />A statistically adequate sample was collected for cover and <br />production on both the previously proposed disposal area and <br />reference area in 1983. An adequate density sample was collected <br />for the sagebrush community in 1981. The following formulae were <br />used to determine adequacy: <br /> <br />NCEC - Coal Ridge #1 3-69 ABC/1145/900301 <br />