Andropogonetum Hempsteadi: A Long Island Grassland Vegetation Type

Abstract

The Hempstead Plains, originally an area of about 50 square miles of natural grasslands, are located in Nassau County, Long Island, New York. The vegetation of this region is somewhat suggestive of the prairies of the Central States but there are many differences in floristic composition and structure. There is now not much of the original grassland of the Hempstead Plains left in a virgin condition, most of it having been converted into truck farms or building sites. However, the unbroken sod is easily recognizable. In places where the sod has been broken and the land allowed to lie fallow for several years there is a slow reversion to grassland. Such communities are marked by the addition of certain weed species and other changes in structure which distinguish them as secondary. Otherwise open ground in the virgin grassland is covered with rootstocks of Andropogon scoparius, the dominant, or with crustose and fruticose lichens and mosses.3 This crust, together with the strong root-competition, make it practically impossible for plants not native to the association to establish propagules. The two factors just named may also help account for the almost complete absence of trees. There are ,several shrubs present in the association. Some of them form rather large patches. Trees, when present, usually are stunted and short-lived. The dominants includet Andropogon scoparius,4 Ionactis linariifolius, Carex pennsylvanica, Aster ericoides, and Baptisia tinctoria. There are many other species present in the association but they are not of high density, coverage or presence. At a distance, the grass-form of Andropogon and the hemispheric plants of Baptisia are alone conspicuous (Fig. 1).