The Impacts of Deer on the Sunken Forest and Fire Island National Seashore, Fire Island, NY, 1967-1989

Art, Henry

One of the most significant biological events in the recent history of Fire Island has been the dramatic increases in the populations of eastern white-tail deer. Field evidence collected between 1985 and 1989 strongly suggests that the deer are responsible for the general decline in the dominance of the herb layer especially so for herbaceous perennials. While the deer may have little impact on most well established, mature trees, they undoubtedly are having an effect on the regeneration of the Forest by differential browsing of species in the herb and shrub layers. It is probable that the decline of shrub species such as Ilex glabra and Gaylussacia bacata are in large part a result of deer browsing. Clearly deer are not the only biological agent changing the plant populations in the Sunken Forest and other parts of Fire Island. Rabbits have long been present and grey squirrels were also introduced onto the island since 1967 (Art, 1987). It is difficult to separate the impacts of deer from other herbivores or even the successional processes of canopy closure by simply examining permanent plots in the Forest. For this reason, in addition to need for data relevant to the prudent management of the National Seashore's natural resources, a deer exclosure experiment was initiated in summer of 1986. These exclosures and their paired control plots were inventoried annually between 1986 and 1989.