Vascular flora and community assemblages of Delhaas Woods, a coastal plain forest in Bucks County, Pennsylvania1

Abstract

The shores of the Delaware River south of the Fall Line in Pennsylvania were once lined with coastal plain forests; however, this forest type is nearly gone from the state due to human activity. One remaining example is Delhaas Woods, a 239-acre coastal plain forest located in Bristol Township, Bucks County. Because of the rarity of this type of habitat in Pennsylvania, a study was developed to characterize the vegetation and community assemblages present at this locality. Site visits were conducted throughout the summer and fall of 2009 resulting in a vascular plant inventory of 373 species, including 297 (80%) native species and 41 (11%) species of concern tracked by the Pennsylvania Natural Heritage Program (PNHP). Oldenlandia uniflora, not previously known to occur in Pennsylvania, and Listera australis, a species new to Bucks County, were recorded. Vegetation transects were conducted using the point-quarter method for tree canopy analysis and the area-plot method for shrub and herbaceous layer analysis, and the resulting data were used to describe and delineate the community assemblages present in Delhaas Woods, two of which, Red Maple-Magnolia Palustrine Forest and Sweetgum-Oak Coastal Plain Forest, are state-ranked rare community types. Preliminary soil investigations were conducted. Locations of PNHP-listed plant species were mapped and management actions were suggested to preserve the integrity and diversity of this unique landscape and biodiversity hotspot.