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or less depending on the height of grasses and the presence of low growing taxa such as <br />rose or snowberry. Each internal observer should also "zigzag" as the team progresses, <br />occasionally turning to view the area just passed to ensure visual coverage of the entire <br />survey path. Constant communication among crew members precludes double counting <br />or missing of plants located along the margins of observed paths. Results from total <br />enumeration efforts can be compared directly with success criteria without statistical <br />testing. <br />Determination of Seedling Emergence <br />At each emergent density sample point (revegetation monitoring only), five one-square <br />foot quadrats should be blindly tossed to the ground and the number of emergents rooted <br />within the perimeter of each shall be recorded accordingly into one of five classes: <br />perennial grass, perennial forb, shrub, annual grass, or annual forb. Where possible <br />recognizable taxa may be recorded by species. Efforts with 1 - 2 perennial emergents per <br />ft2 are considered to be fair, 2-3 perennial emergents per ft2 are considered to be good, <br />while 3-4 perennial emergents per ft2 are considered very good. Five or more perennial <br />emergents per ft2 are considered to be excellent. <br />Sample Adequacy Determination <br />Sampling within each monitored unit shall be conducted to a minimum of 5, 15 or 20 <br />samples as necessary. Sampling within each unit under consideration for bond release <br />shall start with a minimum of 15 (reference area) or 20 samples (revegetated area) and <br />continue until a statistically adequate sample (if necessary) has been obtained in <br />accordance with Section 4.15.11 (2) (a). From initial sampling efforts, sample means and <br />standard deviations for total non-overlapping vegetation ground cover, production, and <br />woody plant density will be calculated. For bond release applications, the typical <br />procedure is that sampling continues until an adequate sample, nmi., has been collected in <br />accordance with the Cochran formula (below) for determining sample adequacy, whereby <br />the population is estimated to within 10% of the true mean (µ) with 90% confidence. For <br />woody plant density, the estimate is to within 15% of the true mean. <br />When the inequality (nmi„ < n) is true, sampling is deemed adequate; and n,,,in is <br />determined as follows: <br />nmin = (t2 S2) / (d X )2 <br />where: n = the number of actual samples collected (initial size = 15 or 20) <br />t = the value from the one-tailed t distribution for 90% confidence with n-1 <br />degrees of freedom (a value of approximately 1.3); <br />S2 = the variance of the estimate as calculated from the initial samples; <br />d = precision (0.10 for cover and production or 0.15 for woody plant density; <br />4.15-32 Revision Date: 3/14/08 <br />Revision No.: TR-72