New Search
Review Draft Eastern Gateway Wetland Restoration Site -- Annual Report <br /> communities. We were also interested in determining the minimum amount of ` <br /> sampling effort necessary to achieve a reasonable level of statistical confidence <br /> in describing existing conditions, and for tracking changes in future years. <br /> Methods: <br /> With these monitoring goals in mind, we considered different vegetation <br /> measurement techniques. We settled on a point- intercept method to measure <br /> cover of the following categories: native species, non - native species, and <br /> Deschampsia cespitosa. We used a nested frequency technique to assess species <br /> diversity and composition in the overall plant community. We did not use the <br /> most commonly used method of measuring vegetation, ocular estimates of <br /> cover, because of problems with lack of precision, lack of repeatability from one <br /> observed to the next, and the large amount of time necessary to estimate cover <br /> for numerous plots with high species diversity. <br /> We began with pilot sampling to gather initial cover data which were then <br /> analyzed in the field, using a laptop computer, to determine the sample size <br /> needed to attain a reasonable level of statistical precision (see Appendix 1). We <br /> determined that use of 15 transects per sample area (a 25m x 45m "macroplot ") <br /> would provide us with a reasonable ability to detect change in vegetative cover <br /> from year to year. For frequency sampling, we utilized the same macroplot <br /> location and dimensions, placing 60 quadrats per macroplot. In all, we <br /> established 3 permanent macroplots, each representing a different point along <br /> the hydrological gradient present on the site. Macroplot #1 was an area of <br /> "typical" Deschampsia cespitosa prairie, #2 was somewhat wetter and an area <br /> representing the emergent meadow and vernal pool communities, and #3 was a <br /> Deschampsia community somewhat elevated with respect to the water table than <br /> macroplot #1. <br /> Results: <br /> A. Cover Sampling: <br /> The purpose of the cover sampling was to assess the relative dominance of <br /> native species vs. non - native species, and also to document changes in the <br /> amount of bare ground and document the establishment of Deschampsia <br /> cespitosa. • <br /> The results of the cover sampling are listed in Table _ , and average cover for <br /> the individual categories is graphed in Figure _ . (NOTE: do we want graphs <br /> as well as tables ?) Overall vegetation cover, averaged over the three <br /> macroplots, was 46.4 %, with a 95% confidence interval of +/- 5.4 percentage <br /> points. These totals varied from a low of 36.1% in Macroplot #2 to a maximum <br /> of 63.7% in Macroplot #3. Though the criterion of 80% over has not been met <br /> Page 9 <br />