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• measured on all shrubs in the shrub density sample quadrats. Input to the <br />regression equation was average height. Crown diameter was inferred from <br />cover and density data. The average cover of each individual shrub species <br />was calculated as the total cover in cm2 per ha divided by the number of stems <br />per ha for that species. The square root of that value was taken to be a <br />reasonable estimate of crown diameter in cm, which was then input to the crown <br />diameter regression equation. The regression equations yield estimates c:f <br />oven dry grams of production per individual. Estimates of shrub production <br />in the vegetation types were made by converting grams to pounds and multi- <br />plying by the number of stems of that species per acre. The resulting produc- <br />tion estimates are therefore expressed in pounds per acre. <br />It should be noted that WRD is well aware that researchers elsewhere <br />have v!orked on estimating shrub production and have developed far more complex <br />methods of statistical treatment. However, time and money constraints in this <br />case did not allow such an elaborate program. The estimates we have made are, <br />we believe, accurate enough to satisfy the needs of CMLRD for these data. <br />2.7 WOODY PLANT DENSITY AND HEIGHT SAMPLING <br />A quadrat system was usetl for sampling woody plant density. A rectangular <br />quadrat (belt-transectl 1 m by 50 m was used for shrubs, while a rectangular <br />quadrat 5 m by 50 m was used for trees lexcept in the Mountain Shrubland vege- <br />• Cation typel. The quadrats were oriented along the cover sampling transect. <br />In the Mountain Shrubland vegetation type, all trees were counted in the <br />affected and reference areas. Tree density was calculated by dividing the <br />total number of trees in the affected and reference areas by their correspond- <br />ing acreages. <br />Shrub heights were taken for each shrub encountered in the quadrats. <br />Average heights are reported for each species. Percent of total shrubs less <br />than 1 foot in height is also reported. <br />2.8 SAMPLE ADEQUACY <br />Sample adequacies for cover, production, and density were calculated <br />separately for the affected and reference areas in each vegetation type. The <br />sample adequacy formula is as follows: <br />__ tz5z <br />nmin IdRI' <br />where nmin = minimum sample size <br />t = t value for 2-tailed test (80% confidence, n-1 degrees of freedom) <br />s = sample standard deviation (n-1) <br />• d = desired detectable change in the mean 110%l <br />x = sample mean <br />-4- <br />