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• sampling centered on the High Density patches was pursued in these areas. Such cover <br />samples as happened to have fallen in High Shrub Density patches of BRB-2 were noted for <br />descriptive purposes. <br />In BRB-3, quantitative density data from mapped shrub patch areas were gathered from belt <br />transects located and oriented randomly within the individual shrub patches. Fifty samples were <br />located in the "High" density patches. The number of samples per patch were proportionally <br />based on the size of the patch. In the Background shrub density portions of BRB-3 an additional <br />approximately twenty sample points (beyond the thirty sampled in conjunction with cover and/or <br />production) were located and sampled for shrub density. The origin of the sample transect in the <br />High density patches was placed in the center of the patch, unless to have done so would have <br />prevented the belt transect sample area from staying within the patch boundaries. If more than <br />one sample point was placed in a patch, they were evenly (uniformly) spaced in the polygon. The <br />belt transects (i.e. elongate sample plots) were 2 m x 50 m in dimension and randomly oriented <br />from the origin. Within each belt transect, all living trees and full shrubs whose root crowns <br />emerge within the plot boundaries were counted by species. Sample adequacy of collected <br />shrub density data from the BRB-3 High density shrub patch sampling were determined as <br />follows: <br />(st)z <br />nmin = <br />where: <br />(dX)2 <br />nm;n =the number of sample points needed in a given vegetation type to be capable of detecting a <br />15% reduction in the mean with 90% confidence; <br />s =standard deviation (n-1); <br />t = the t statistic (one-tailed; 90% confidence; n-1 degrees of freedom; if n>30, t = 1.282 for <br />purposes of this study); <br />d =acceptable amount of inherent variability to be identified between the sample mean and the <br />true population mean (0.15 for purposes of this analysis); <br />12 <br />