REP31644 - Laserfiche WebLink

Home Browse Search

~• Preliminary sampling indicated that approximately 13 transects were needed to obtain statistigl sample adequacy. Calculations of minimum sample size ruing the 13 transect sample indicated that sample adequary was actually reached after 3 samples (x = 56, s' = 53.06). Thus, the sample data was determined to be statistically representative of the reclaimed mine site and vegetative cover sampling was discontinued. Site vegetative cover has substatially increased over the values obtained during the 1985 vegetation survey. The minimum cover value of 4a percent is more than double the highest 1985 value of 20 percent and the maximum cover value (67 percent) is more than three times the 1985 maximum cover estimate. Although, overall cover is visibly improving, there are some areas where the vegetative cover consisu mostly of noxious species such as Lactucn serriola. This condition appears relatively unchanged from 1985 observations. Herbaceous Production Total herbaceous production for the site was approximately 550 pounds per acre. Plano clipped in the production quadrate were separated into five groups, based on life form (annual grass, perennial grass, biennial (orb, and perennial (orb) and origin (native and introduced). Perennial native grass accounted for the greatest production with approximately 280 pounds per acre. Perennial introduced grass produced almost as much as the perennial native grass, 200 pounds per acre. Together, these two groups accounted for almost 86 percent of the annual herbaceous production on the site. The remaining yield was produced by perennial introduced Corbs (70 pounds per acre), biennial introduced Corbs (9 pounds per acre), and biennial native (orbs (less than 1 pound per acre). Production by species is shown in Figure 1. Preliminary sampling indicated that a relatively large sample size (n = 112) was required to meet statistical sample adequacy. However, satisfying that objective was unfeasible due to time constrainu. In addition, published sample number guidelines suggest that attaining such a sample size is unrealistic (OSM 1985). Thirty-seven production quadrats were completed in the available field time. Adequacy tesu using date from these 37 quadrau indicated that approximately 65 quadrau were needed to meet statistical sample adequacy requiremenu. The conclusion drawn Crom these [esu was that production was too variable to meet statistical adequacy tesu in a realistic number of samples and more time is needed for production to equalize across the revegetated area. Woody Plant Density Mean shrub density was approximately 20 stems per aae. This density is considerably less than [he revegetation success criterion of at least 500 stems per aae (Sun Coal Company 1986). Of the six shrub species seeded on the site, only two species, Purshia rridentata and Aunus virginianus were detected. Three additional species were observed on the site but not detected in sampling quadrau: Chrysothamm~us nauseosus, Antelanchier alnifolin, and Rosn woodru. In addition, one species (Artemisia tridenrara) that was not part of [he seed mixtures applied to the site was observed growing on site. Scattered clumps of transplanted Aunus virginianus were observed but not detected during sampling. Most of the clumps appeared to be marginally alive. Species Diversity Approximately 30 plant species were identified during the 1988 revegetation monitoring survey. Table 2 lisu recorded species and indicates which were not detected on transecu or in quadrau bu[ were observed on the site. Although a[tempts were made to iden[ify all species occurring on revegetated area, some species may have been missed due to the time of year and desiccated nature of many planu.