Survey of Plants in Van Cortlandt Park Turns up Surprises

Jack Henning as he surveys the plant life of Van Cortlandt Park. Photo by Sophia Tewa.

When Jack Henning is not teaching biology at Lehman, he can be found in the swamps and woodlands of nearby Van Cortlandt Park, conducting an exhaustive survey of its entire flora that has uncovered numerous surprises, from the impact of pollution and acid rain to the slow return of a wetland drained years ago by Robert Moses to build new highways.

Among his principal findings are:

The park has 1,065 species of plants, more than twice the number previously counted, which makes it home to more species of plants than Central Park.

  • At least half of the listings are non-native plants, and among the native plants, a surprising number have not been previously recorded in this area. Some are considered rare, unusual, and threatened for New York State.
  • Acid rain and pollution have led to high levels of lead in the soil of certain areas, which have caused some native species, such as the entire Orchid family, to virtually disappear from the park except for one invasive European species.
  • Some of the rarer species have probably either lost their natural pollinator or become reproductively isolated from other populations due to the surrounding apartment buildings and residential neighborhoods.
  • A wetland, previously part of a swampy bird sanctuary drained by Park Commissioner Robert Moses in the 1950s, is slowing returning inside Croton Woods at the northeastern end. The wetland was drained to facilitate the building of three multilane highways through the park. In the past few decades, as the Parks Department has struggled to keep up with maintenance costs throughout the city’s many parklands, the drainage canals placed by Moses in that area have silted in, and the swamp has returned.

Consisting of more than 1,000 acres, Van Cortlandt is the city’s fourth largest park and borders the communities of Riverdale, Kingsbridge, Norwood, and Woodlawn, as well as the city of Yonkers. Earlier surveys, conducted by the New York City Department of Parks & Recreation in 1988 and 2008 and by Penn State University Professor Robert Loeb in 1983, were more dedicated to documenting the woody canopy layer of Van Cortlandt than its underlying herbaceous layer. Henning conducted this latest survey year-round for four years in a row and also included the planted flower beds found throughout the park.

Overall, he says, the results demonstrate the need for conservation in city settings. “Given that most humans now reside in city regions,” he explains, “better understanding of urban ecology is of dire importance. We cannot afford to ignore any of the plants around us, native or not, since humans cannot exist without land plants. Van Cortlandt Park is a valuable example of this, since few people are acknowledging the diversity that can exist in a highly disturbed environment like a city setting.”

This spring, Henning’s work was recognized by the New York Flora Association (NYFA), which promotes plant conservation in the State. He earned the group’s “Best Botanically Oriented Poster” award for his presentation at its annual Northeast Natural History Conference. “What I think surprised the NYFA is that I had found such richness in a city setting,” Henning says. “This richness is potentially good since it may make the environment more resilient to future disturbance.”

Henning, who will use the data in his forthcoming doctoral dissertation, has spent over thirty-five years working with plants. His career took him to England, where he trained at the Royal Botanic Gardens-Kew in 1983, and to the University of Cape Town, South Africa in 2002, where he earned his second master’s degree, in systematics and biodiversity science. In pursuing his doctoral thesis at CUNY’s Graduate Center, he hesitated between several worldwide projects in South Africa and Peru, among others, but finally decided on a local project using Lehman as his home campus, hoping to shed light on the complexity of Van Cortlandt Park’s urban ecology. In 2008, he was chosen as Lehman’s Adjunct Teacher of the Year.