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05-19-1997 13:12 612 625 5212 UM FOREST RESOURCES P.02/09 <br />Compoiition md itnicture of the vegetstlon of Medina 26 woodi. A report for Spring HIU <br />Golf Qub, by Lee E. Frelich. May 19,1997. <br />Methodi <br />Scanpling. A stratified random sampling strategy was used. The ‘bigwoodi’ forest area was <br />divided into 6 units prior to visiting the Kte in the field. The distribution of wetlands and other <br />non-bigwoods vegetation types, and topography suggested the logical division into 6 units. A <br />total of 30 plots were placed throughout the bigwoods area, and the number of plots in each of <br />the 6 units was proportional to its area. <br />Nested fixed radius plots were used in which an outer circle delimited the area within which all <br />trees were sampled, and a nested inner circle delimited the area within which seedlings, shrubs and <br />herbs were sampled. Initial experimentation in the field suggested that a fix^ radius of 7 meters <br />would be large enough to obtain an adequate number of trees for analysis, without taking a lot of <br />redundant dau. All trees >1.4 meters in height were tallied, and diameter was measured for all <br />those Uees >3.0 cm dbh. Additional data recorded for each tree included species, crown class <br />(overstoiy, receiving direct sunli^t firom above, or understoiy, not receiving direct sunlight firom <br />above), and quality of the tree (scale of 1-5; 1-perfect forest grown form and free from defect to <br />5=formerly open grown tree vwth many low branch stubs and rotten trunk). At this time of year it <br />is difficult to separate sugar maple from black maple, and therefore these two taxonomic units <br />were merged into sugar maple. A total of 4618 square meters of land area were sampled among <br />the 30 tree plots, approximately 3.9% of the total bigwoods area. <br />The nested plots were 2 m in radius. All species of tree seedlings, shrubs, and herbs were taUied <br />and assigned to abundance classes (1-5,6-10,11-20,21-50 and >50 individuals present). <br />Approximately 0.3% of the total bigwoods area was included in this analysis. Addition^ species <br />that occurred in the bigwoods, but not on the plots, were also noted so that a total species list <br />could be constructed. <br />Data analysis. Diameter-frequency distributions for all trees, all trees >10 cm dbh, overstory <br />trees, and understory trees allow interpretation of the structure of the forest. <br />To examine species composition, the number of live stems and proportion in each species, and the <br />live basal area of each species was calculated for all 30 plots combined. Experimentation with the <br />data showed that proportion of live basal area in each species was the most informative, and so <br />that was calculated separately for each of the 6 sampling units. <br />For tree seedlings, shrubs, and herbs, the frequency was calculated as the proportion of the 30 <br />plots on which each species occurred. The mean number of herbaceous species among the 30 <br />plots (area-12.6 square meters) was also calculated.