Is Street Tree Diversity Increasing in New York State, USA?

Diversity in tree populations is viewed as essential for protecting the public investment in urban trees and for preserving the environmental, social, and economic benefits that these trees provide. It is therefore crucial for officials responsible for the management of municipal trees to know the diversity of their municipal tree populations and whether their efforts to increase diversity have been effective or should be modified. We assessed street tree diversity in New York State, USA by analyzing municipal street tree inventory data from two data sets, the first comprised of 75 inventories collated from municipalities, and the second comprised of 32 sets of inventories conducted at multiple points in time. This analysis builds on two previous papers containing similar assessments by analyzing more current data and by calculating diversity index statistics and relative abundance percentages for prevalent street tree species and genera. Findings indicate that there has been substantial progress to increase street tree diversity in New York State. This progress is correlated with reductions in the dominance of Norway maple (Acer platanoides), the state’s most prevalent street tree species (17% of street trees statewide), and in the dominance of maple (Acer), the state’s most prevalent street tree genus (35% of street trees statewide). Work remains to be done to further increase species and genus diversity so as to meet the challenges posed to municipal street tree populations by invasive pests and climate change. Strategies are proposed for accomplishing this.