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• where x, = mean cover or production for the affected area xz = mean cover or production for The reference area t = a t-statistic value, which varies depending on desired level of confidence and sampling size 5~ = the variance of cover or production for the affected area 5= = the variance of cover or production for the reference area n, = sample size in the effected area n, = sample size in the reference area When ~x, - xz~ is less than or equal to the other calculated value, the affected area and reference area are considered comparable for the pur- pose of evaluating reclamation success. 2.4 Reference Aree Sampling Design All sample sites were located by a random process. The southwestern • corner of the reference area served as the intersection of an x and y coor- dinate system. Positive coordinates were produced by a random number generator. The exact sample point was then pacetl off by the field ecologist. 2.5 Measurements 2.5.1 Collection end Analysis of Cover Data Cover was estimated using a point-intercept method along randomly located and oriented transacts (Mueller-Dombois and Ellenberg 19741. Twenty points were sampled along the 50 meter length trensect. Paired points were sampled at each 5 meter interval of the trensect. Eacn paired point was 0.75 meter from the trensect end perpendicular to the trensect. The siting device was mounted on en adjustable tripod to facili- tate vertical orientation and point stabilization. Fine cross hairs were used in The siting device to provide optimum point definition. AT each sample point, the siting device was first directed vertically upward, then vertically downward and the first hit recorded. If woody vegetation (tree antl/or shrubl was intercepted a second or third hit was taken until either herbaceous vegetation or rock, litter, or soil was hit. Vegetation hits were recorded by species. Only first hits were used in calculating percent COVer. • -3-