Effectiveness of Transplanted Woody Plants in Inhibiting Re-growth of Phragmites australis and Other Herbaceous Plants

Byer, Michael; Ansel, Jessica

As in many National Parks and other public lands, much of the land area at Gateway National Recreation Area is overrun with invasive plants. These plants mostly belong to alien species or genotypes (Westbrooks 1998). These invasives typically grow in near-monocultures, which obliterate native plant communities or prevent them from developing. Originally, the NPS mission to "preserve and protect" was usually interpreted as a "hands off" policy, i.e., we should care for and maintain existing biological communities without intervention or manipulation ( 19 ). If applied to monocultures of invasive species, however, such a policy is counterproductive, for widespread takeover of areas by invasive plants in itself constitutes an alteration of the natural order ( 19 ). It poses a threat to natural communities composed of native species and reduces biodiversity. According to a recent estimate, invasive plants infest 4,600 acres (over 7 square miles) of federal land daily, an area larger than the state of Delaware each year, and in 1996 already occupied about seven million acres of National Park Service land (U.S. Dept. of the Interior 1996). Consequently, natural resource managers of National Parks and other public lands are now generally agreed, these plant invasions should be controlled or counteracted when possible ( 19 ). One way in which this can be accomplished and biodiversity regained, albeit not usually with ease, is by I Gateway National Recreation Area, Division of Natural Resources, 210 New York Avenue, Staten Island NY 10305. 2 Rutgers University, Department of Biology, New Brunswick NJ __ restoring infested areas, replacing the invasive plants with native species ( 19 ). Although it has not been economically feasible to restore invasivedominated areas on a large scale at Gateway, we are attempting to replace the invasive plants in small areas with communities of native plants appropriate to the soil, hydrology, and other environmental conditions prevalent at the site. Since most of the land within the Jamaica Bay District of the park (see map, Fig. 1) is composed of dredge spoil deposited during the early decades of the 20th century ( 19 ), the vegetation of those sites not dominated by invasive plants is successional. In restoring sites, we have tried to circumvent natural succession and create quasi-climax plant communities by planting the climax species directly. In this fashion, we hope to develop vegetation at these sites that, although native and adapted to site conditions, is unique to the park. This will increase biodiversity and provide added interest to park users, thus increasing the value of our natural resources, especially if accompanied by appropriate signage.