A first approximation of the historical and extant vascular flora of New York City: Implications for native plant species conservation1

Journal of the Torrey Botanical Society, Jul-Sep 2004 by DeCandido, Robert, Muir, Adrianna A, Gargiullo, Margaret B

DcCANDIDO, R. (Department of Biology, The City College of the City University of New York, New York, NY 10031), A. A. MUIR (Graduate Group in Ecology, 2148 Wickson Hall, University of California, Davis, CA 95616), and M. B. GARGIULLO (City of New York Department of Parks and Recreation, Natural Resources Group, 1234 Fifth Avenue, New York, NY 10029). A first approximation of the historical and extant vascular flora of New York City: Implications for native plant species conservation. J. Torrey Bot. Soc. 131: 243-251. 2004.-This historical and extant vascular flora of greater New York City is a literature review supplemented with field work and examination of herbarium specimens held in New York State. For the historical and modern periods combined, 2177 species in 779 genera and 161 families were found in New York City. The City retains 57.4% of its native plant species diversity with 779 extant native species compared to 1357 ever recorded. Extirpations have disproportionately affected native vs. non-native species. Staten Island (Richmond County) has the greatest diversity of the five boroughs with 154 families and 1633 species known from both the historical and modern time periods combined, as well as the greatest number of extant species (921), and the greatest number of native extant species (621). However it has lost approximately 35% of its native flora in the last 70 years. Brooklyn (Kings County) has the lowest diversity of any borough with 695 native and alien species known from both the historical and modern periods combined. Manhattan (New York County) and Brooklyn have lost more than 75% of their native species. Queens County has lost the greatest number of native species (585). In New York City since the mid-19th century, 46.4% of all native herbaceous species have been extirpated, while 22.9% of native woody plants have been lost. In the last 70 years, extirpations have continued even in natural areas protected in parks. Strategies are recommended for preserving New York City's significant native plant species diversity.

Key words: New York City, native species, historical flora, extant flora, diversity, extirpation.

Urban areas present opportunities to study changes in plant species diversity. There can be a history of species collected at particular sites documented with herbarium specimens, published papers, field trip accounts, personal notebooks, and lists that may extend back to the early 19th century. In New York City, remaining natural areas are easily accessible and can be surveyed frequently, facilitating comparison between time periods. From a broader perspective, the study of urban environments is important because most people in North and South America, Europe, and Australia now live in cities. The urban environment is overlooked by many ecologists, yet encountered by most people on a daily basis (McDonnell and Pickett 1990). By 2025 it is expected that almost two thirds of the world's people will live in urban areas (World Resources Institute 1996). Throughout the world, many conservation areas and nature reserves are becoming isolated habitat fragments as land around them is developed. Understanding the effects of rapid development and urbanization upon plant species diversity will help biologists decide which kinds of species and habitats to watch carefully in the coming years, as development and urban sprawl affects an increasing number of natural areas throughout the world (Thompson 1994).

New York City (40°(47' N, 73°(58' W), is located between the Atlantic coast, Long Island Sound and Hudson River estuary in the southern most part of New York State (Figure 1), and encompasses diverse geologic and geographic areas. As a result, numerous ecosystem types and high numbers of native plant species occur in an area that is relatively small compared to the rest of New York State. Overall, 60.3% of the native plant species ever recorded in the state have been collected in New York City.

The formal study of the flora of New York City began with John Torrey and his catalogue of plants found in the vicinity of New York (Torrey 1819). Beginning in the 1880s with the creation of the New York (Bronx) Botanical Garden, a significant effort was made under the aegis of the Torrey Botanical Club to collect plant species from the metropolitan area (Rusby 1906a, 1906b). Early botanists and naturalists who collected plant specimens in New York City and environs included Nathaniel Lord Britton on Staten Island (1875-1930, see Britton 1877, 1880; New York Botanical Garden 2003); William T. Davis on Staten Island (1870-1935, see Davis 1892a, 1892b, 1895, 1902, 1917, 1918); E.P. Bicknell in the Bronx (1875-1901, see Bicknell 1898, Griscom 1926); Harry Ahles in the Bronx (1946-1950, see Ahles 1947, 1948, 1951; Tippo 1982); and Sam Yeaton in Queens (1925-1988, see Yeaton 1988).

Historically many plant species throughout New York City, were found or collected from locales that were not parkland at the time; these areas have since been developed (see Griscom 1926, Sefferien 1932, Kieran 1959). In the Bronx and Manhattan, most of the parks with the largest natural areas were established in the 19th century, while in Brooklyn, Queens and Staten Island, most parks were established in the 20"' century (Table 1). Significant portions of many natural areas of parks in the boroughs outside of Manhattan were converted into landfills from the 1930's through the 1970's (Caro 1974, Pons 1987). Development, although on a smaller scale, continues to the present. Today, the City of New York Department of Parks and Recreation owns and maintains approximately 11,332.0 hectares of parkland, yet only those parks listed in Table 1 have significant tracts of natural areas. The Federal Government owns approximately 3,645.0 hectares in Brooklyn, Queens and Staten Island as part of the Gateway National Recreation Area. Other agencies own smaller parcels of parkland: the New York State Department of Environmental Conservation owns 177.4 hectares throughout the city and New York State Parks owns 41.0 hectares of natural area on Staten Island. Overall, 17% (14,175.0 hectares) of New York City (83,365.2 hectares) is designated as parkland. However, only about 25% of this parkland (3543.8 hectares) can be considered "natural area," specifically set aside to protect and maintain the flora and fauna found therein.