Urban and suburban trees can provide a wide range of societal benefits such as decreased building energy usage, increased property values, improved human health, and aesthetic beauty. Many municipalities in the New York City metropolitan area are pursuing greening initiatives to maintain and increase these positive ecosystem services for their citizens. Unfortunately, these greening initiatives face difficult challenges, which include an increasing frequency of severe storm events due to climate change, loss of tree and forest cover due to land development, and possibly increasingly negative attitudes towards urban trees as a result of tree-fall damage during major storms. These problems are compounded by a lack resources to monitor and respond to changes in tree canopy over time. To help address these challenges, I will present 1) a method for analyzing tree canopy and land use change over time that is potentially suitable for use by citizen scientists, 2) estimates of tree canopy change across a 180 km urban-to-rural gradient from New York City to eastern Long Island, 3) insights into the major drivers of tree canopy loss across this gradient from 2001 – 2016, and 4) an analysis of the relationship between protective tree ordinances and patterns of canopy change.
Results/Conclusions
We found strong evidence that tree canopy loss far exceeded rates of replacement across our urban-to-rural gradient. When evaluated on an absolute basis, canopy losses were greatest in less-densely-populated portions of the gradient, where new development accounted for a large proportion of net canopy loss. However, when rates of loss were normalized based on 2001 tree cover, the opposite was often true: older, high-density suburban areas often had greater proportional tree canopy loss than exurban and rural areas. Municipalities with strong tree ordinances did not appear to have significantly lower rates of tree canopy loss than neighboring areas. These results suggest that high rates of urban canopy loss are not isolated to fast-developing exurban areas. Furthermore, the presence of strong tree ordinances, alone, are not enough to prevent rapid declines in urban forest area, given high rates of non-development-related tree loss and comparatively low recruitment of new trees into the urban forest.