Laserfiche WebLink
RULE 4 PERFORMANCE STANDARDS <br />along the margins of observed paths. Results from total enumeration efforts can be compared directly <br />with success criteria without statistical testing. <br />Determination of SeedlinEmergence <br />At each emergent density sample point (revegetation monitoring only), five one -square foot quadrats <br />should be blindly tossed to the ground and the number of emergents rooted within the perimeter of each <br />shall be recorded accordingly into one of five classes: perennial grass, perennial forb, shrub, annual <br />grass, or annual forb. Where possible recognizable taxa may be recorded by species. Efforts with 1 — 2 <br />perennial emergents per ftZ are considered to be fair, 2-3 perennial emergents per ftZ are considered to be <br />good, while 3-4 perennial emergents per ftz are considered very good. Five or more perennial emergents <br />per ftZ 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 samples as <br />necessary. Sampling within each unit under consideration for bond release shall start with a minimum of <br />15 (reference area) or 20 samples (revegetated area) and continue until a statistically adequate sample (if <br />necessary) has been obtained in accordance with Section 4.15.11 (2) (a). From initial sampling efforts, <br />sample means and standard deviations for total non -overlapping vegetation ground cover, production, and <br />woody plant density will be calculated. For bond release applications, the typical procedure is that <br />sampling continues until an adequate sample, nmin, has been collected in accordance with the Cochran <br />formula (below) for determining sample adequacy, whereby the population is estimated to within 10% of <br />the true mean (g) with 90% confidence. For woody plant density, the estimate is to within 15% of the <br />true mean. <br />When the inequality (nmin < n) is true, sampling is deemed adequate; and nmin is determined as follows: <br />Nmin — (t2S2)1(dE)2 <br />where: n = the number of actual samples collected (initial size = 15 or 20) <br />t2 = 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 />x = the mean of the estimate as calculated from the initial samples. <br />If the initial samples do not provide a suitable estimate of the mean (i.e., the inequality is false), additional <br />samples should be collected until the inequality (nmin :5 n) becomes true. However, where sampling is <br />for managerial (monitoring) information, adequacy is not necessary and is calculated for informational <br />purposes only. <br />If reverse -null testing will be utilized to document success, then in accordance with Rule 4.15.11 (2) (c) a <br />minimum of 30 samples must be collected and a demonstration of sample adequacy is not necessary. In <br />this circumstance a two -sample reverse null t-test is mandated along with Satterthwaite approximated <br />degrees of freedom and standard error. However, if an adequate sample can be obtained from the <br />reference area, then a less complex one -sample t-test may be utilized. With the reverse null test, the <br />smaller the variance (given by extra sampling) the better the chances of passing closely matched <br />parameters. <br />Rule 4 Performance Standards 4-71 Revision Date: 1/31/18 <br />Revision No.: TR -119 <br />