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MRwww.bio-geo.com <br /> <br />Cover will be measured by a point intercept method. From random sample points, a 100 foot <br />tape will be stretched at a bearing of magnetic north (if a bearing causes the tape to cross the <br />study area boundary, then bearings of east, south, or west will be substituted, in that order). At <br />10 foot intervals along the tape beginning at 10 feet, a point frame will be positioned <br />perpendicular to the tape and extended to the left. The point frame consists of a metal bar with <br />tripod legs, positioned parallel to the ground about 1 meter high. A sliding laser light pointer is <br />positioned at each of 10 marked points along the bar spaced 10 cm apart. At each point the <br />observers will record the object that first intersects the downward-pointed laser light (plant <br />species, litter, rock, or bare ground). Ten cover readings at each of 10 intervals along the <br />transect will yield 100 cover readings per transect, which will be tallied and the total number of <br />hits per species or object will be equal to the percent cover estimate for that transect. <br />For cover measurements, sample size will be determined as specified in Section 2.3. Sample <br />adequacy will be calculated periodically in the field during sampling by entering cover data into a <br />field laptop computer. A simple random sampling design will be employed, and samples will be <br />taken in the order of the arbitrary numbers assigned to random points. <br />Definitions <br />Cover. CDRMS regulations allow cover to be defined as either canopy or basal cover of living <br />herbaceous or herbaceous and woody vegetation. For this study we will use canopy cover and <br />utilize absolute cover of desirable perennial herbaceous species. <br />2.3 Statistical Procedures <br />Sample adequacy will be calculated using equation 1. A minimum sample size of 15 will be <br />required. <br />Equation 1 t'?Z <br />where: <br />n. = minimum sample size <br />sr = Sample variance (n-I degrees of freedom) <br />d = Precision (0.10 for cover and production; 0.15 for woody <br />plant density) <br />z = Sample arithmetic mean <br />t = The ((x=.10) t-table value for a 1 tail t-test, n-1 degrees of <br />freedom (infinite degrees of freedom may be used if n>30) <br />n = Sample size <br />Inc. <br />4