New York City parks serve over 8.6 million residents in the five boroughs. Promoting city parks has been a major component of city’s strategic plans for decades. A multitude of projects had been carried out to introduce and increase plants across the urban landscapes. Yet it is not known: (1) how plant species and composition change spatially and temporally, (2) how plants interact with residents with uneven distributions of social equality and management practices. Here we performed a spatiotemporal analysis on plant diversity and community composition based on the NYC Entitation database that was constructed spatially from field surveys in 57 parks during 1985-2015. Both aerial photograph interpretation and field reconnaissance were used to conduct the surveys. We delineated four neighborhood zones within 250, 500, 1000 and 2000 m from park borders to calculate population density (No. m-2), residential area (m2), median family income ($), and percent below poverty. Spatial connections between these social measures and plants are quantified to test a hypothesis on neighborhood inequality in terms of species assets (e.g., native vs exotic species) reflected from social measures and management practices.
Results/Conclusions
A total of 528 plant species, including 304 native (57.6%), 162 exotic (30.7%), and 62 unidentified (11.7%) species, were recorded in 57 parks during 1985-2015. Species diversity appeared positively correlated with park size (p<0.001) and increased in the past three decades. Wealthier neighborhoods seemed to have disproportionally lower number of exotic species per unit land area than the landscape averages. There were four parks (Van Cortlandt Park, Riverdale Park, Givans Creek Woods and Hart Island Park) that were surveyed twice (1988-1990, 2007-2015). Hart Island Park had no management practice due to its unique function as a common cemetery, resulted in a significant increase of exotic species from 50% to 88% during the two periods. The other three parks had significant increase of species diversity during the same periods (equivalent for both native and exotic species), partially due to active management and restoration projects. Some exotic woody vines expanded widely in Van Cortlandt Park (e.g. Celastrus orbiculata from 10.0% to 11.3% and Ampelopsis brevipedunculata from 2.5% to 5.2%) in the past 22 years, while others did not (e.g. Lonicera japonica from 1.9% to 0.7%). Exotic tree Acer platanoides did not expand (from 18.5% to 13.8%), neither did its native congener Acer rubrum (7.9% to 6.1%) in Cortlandt Park over the years.