2012-03-09_REPORT - C1981019 (9)

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Given the value of data collected in 2005, Cedar Creek determined that a second tier of 0.1 -acre plots both within and exterior to the fenced enclosure was warranted to significantly improve the statistical power of the effort. The second tier of plots was established some distance from the first tier (Map 4) to provide additional representation of the overall area. This brought the total evaluated area to approximately 2.0 acres (two 0.1 acre plots within each long -axis treatment area both within and external to the fenced enclosure) for a total of 20 plots. In 2009, biennial sampling was initiated, effectively separating the sampling regime into an alternating pattern for plots 1 -5 and plots 6 -10. Data were collected from plots 1 -5 inside and outside the fence in 2009 and then data were collected from plots 6 -10 inside and outside the fence in 2010. After a thorough review of historical data (2006- 2011), it was determined that these populations are still in the process of stabilizing as there is still a high level of variability within, between, and across treatments. It also appears that the physical proximity of the fence to plots 1 -5 is having some modest effect on the treatment results thereby introducing additional variability. Data from 2006 -2011 (not 2005) were used for this analysis because there was a consistent methodology employed over this period and there was a larger data set available due to the ten additional plots added in 2006. The means of the dependent variables of woody plant density, shrub cover, and herbaceous cover from 2006 -2011 for each plot were compared against each replicate plot for each treatment both inside and outside the fence; i.e. plot 1 vs. plot 6, plot 2 vs. plot 7, etc., using a paired student's t test. This analysis demonstrated that there was at least one treatment pairing that showed a statistically significant difference between plots that were close to the fence versus plots further away from the fence. It is hypothesized that the difference in plot performance can be attributed to improved growing conditions for plants in the immediate vicinity of the fence due to captured blowing snow and plant litter. Due to differences in treatment performance with proximity to the fence, the sampling regime was changed from an alternating schedule where plots 1 -5 would be sampled in odd numbered years and plots 6 -10 sampled in even numbered years to a sampling regime in which plots 6 -10 will be sampled every year with the addition of plots 1 -5 every third year. This pattern should continue until it appears that the shrub population has reached equilibrium and inferences about population dynamics can be made with greater confidence than currently exists. This means that in 2011, plots 6 -10 inside and outside the fence were sampled and in 2012, 2015, etc. all plots will be sampled. The change in sampling regime is an effort to try and reduce costs to Colowyo while maintaining study viability and the collection of usable data for monitoring shrub population dynamics, and most importantly, to validate or refute TR -72 revegetation success criteria based on sound scientific and statistical evidence. Cedar Creek Associates, Inc. B - 2 Colowyo Mine 2011 Revegetation Monitoring Report