Vegetative inventory & classification of Martha's Vineyard's coastal pond cove wetlands

Tofte-Dorr, Leah
Rick Van de Poll
Department of Environmental Studies
A vegetative inventory of Martha's Vineyard coastal pond coves was conducted during the summer of 1997 in an effort to identify vegetative community types and to aid in their mapping. This study collected base line data about the vegetative composition of these coves and compared the vegetative communities to regional community alliance descriptions developed by The Nature Conservancy (TNC). The wetlands were stratified according to physiognomic class and sampled with releve plots. Plot size was determined by stratum: 10m squared for forested wetlands, 5m squared for shrublands, and 1m squared for herbaceous or non-vascular plants. Within each plot the percent areal cover for each species was estimated to the nearest five percent. A total of fifty-one releve plots were taken in eleven separate coves. Within these plots on hundred and two plant species were identified. The data collected was entered into a database and exported for multivariate analysis in Twinspan. The output from this analysis was interpreted and divided into groups or plots belonging to the same community type. The plot groups were then compared to TNC alliance descriptions. Field observations were used to determine alliances fro all fifty-one plots. The Twinspan groupings differed from field identification alliance assignments in ten out of the fifty one plots. These differences arose from strata information not taken into consideration in the Twinspan analysis. Discussions of these differences can be found in the results section. This report details the methodology used as well as the results found. Included are summaries of the documented alliances found, species lists of all plots, relative frequencies of alliances found in this study, Twinspan output and interpretation, as well as observations of relevant field information.

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