Plant communities and Flora of Robins Island (Long Island), New York

The Coastal Lowland Ecozone of New York State has been greatly dissected and altered from its natural state. Robins Island represents one of the few undeveloped and relatively intact ecosystems remaining in this ecozone; it offers a unique opportunity to study the region's natural processes. The plant communities of Robins Island were inventoried using a combination of belt transects and quadrats. A total of 12 natural, non-lacustrine plant communities ranging in size from 0.1 to 108 hectares were identified on Robins Island: three forest, two shrubland, two grassland, three palustrine, and two sparsely vegetated communities. The Bayberry-Phragmites community contained a combination of xeric (e.g., Myrica pensylvanica) and hydric (e.g., Phragmites australis) species that have not been reported in other natural circumstances. The island's other communities were similar to descriptions of other regional plant communities, although Robins Island's communities were relatively depauperate. Based upon a detrended correspondence analysis, variability among each community's transects ranged from high to low; this variability was associated with the random sampling design, inherent heterogeneity, physiographic characteristics, and edge effects. The island's flora consisted of 215 species of vascular plants representing 151 genera and 60 families; seven species were rare or endangered in New York State and 30% of the flora was non-native and naturalized. The flora showed a greater similarity to neighboring Shelter Island (Sorensen's similarity index [SSI] = 55%) than to the adjacent north and south forks of eastern Long Island (SSI = 36 and 38%).