Planting native plants outside of New York City’s natural ecosystems cannot contribute to the biodiversity of those ecosystems, and is therefore not required by this manual. Indeed, outside of the Forever Wild and natural areas identified in the next chapter, emphasis will be placed on increasing the proportion of native plants used in Park plantings.
We can seek to restore or increase ecosystem health and attempt to restore and expand ecosystems on their edges, but there is no scientific proof that planting out into the built city will benefit adjoining ecosystems. However, it does not mean that native species cannot serve an important role in infrastructure improvements.
Role of native species
A good example is the current experiment between Columbia University and Parks to establish green roof plantings utilizing regionally native plant species. Two regional ecosystems, Hempstead Plains and Rocky Summit ecosystems, were chosen for this experiment because they closely mimicked the conditions encountered on rooftops — hot, well drained, and drought-prone.
The project is not seeking to create extensions of Hempstead Plains and Rocky Summit ecosystems onto the roofs of New York City; it is impossible to successfully transplant the totality of these ecosystems in all their biological complexity. Rather, the project sought to exploit existing knowledge of these species as they function in their natural ecosystems to create beauty and ecosystem services on rooftops.
Parks will continue to increase its use of native species in ornamental plantings designs and in right-of-way areas as appropriate. Native species have evolved to local environmental and edaphic conditions, and many have utilitarian and aesthetic qualities that can be of service to those responsible for designing and maintaining the public landscape as well as to individual property owners who seek to enhance their own backyards or street tree pits.
Parks is fortunate to have at its disposal a facility dedicated to the propagation and production of the flora of New York City‟s native ecosystems – Parks Greenbelt Native Plant Center. This facility exists primarily in support of efforts to conserve, manage and restore the City‟s ecosystems.
Furthermore, it produces plants only from locally sourced, genetically rich plant populations, which contributes significantly to maintaining the genetic integrity of New York City‟s surviving ecosystems- a critical factor in maintaining biodiversity. Over the twenty years of its existence, GNPC has learned to grow roughly two thirds of the species still to be found in New York City‟s ecosystems.