Major Storms and New York City Trees: An Analysis of Damage and Tree Characteristics

Coastal cities such as New York face the challenge of preparing for life with stronger and more frequent storms. With this in mind, the city of New York has steered its use of data toward better preparing for the next big storm. City officials challenged the Capstone team to investigate the damage done to street trees, a subset of all trees found on public land, during major weather events. The city wanted to know which trees are more vulnerable than others to better focus its resources during the critical hours before and after a major storm.

The project examines large amounts of public data and draws from the insight of practitioners knowledgeable about which sizes and types of trees might better withstand major storms. Three sets of data are used as inputs. First is information from the city’s service-request and -complaint center — its 311 system. The data covers requests, specific to tree service, spanning four years and seven major storms, starting with a series of strong winds in 2009 and ending with Superstorm Sandy. It excludes one of those seven storms — tornadoes in the boroughs of Brooklyn and Queens in late 2010 — given its unusually localized impact. Second is data from the New York City Department of Parks and Recreation (Parks Department) regarding actual work done over the same period. Third is data from the city’s tree census.

The team found that the city’s two most populous tree species show the most vulnerability during major storms. The analysis clearly showed that Norway maples are more vulnerable than other species during major storms and provides preliminary signs that the London plane tree could also be more vulnerable. Regarding size, the same can be said for larger trees. The team saw inconclusive evidence regarding other species and sizes. Regarding geographic distribution, the western border ZIP codes of Staten Island and the northern and eastern ZIP codes of Queens experienced the greatest damage during major storms.

The team recommends that Parks take a more structured approach in future analysis of storm damage. It suggests, most specifically, the use of storm windows similar in structure to the ones designed by the capstone team. Failing to use a standardized method results in arbitrary distinctions between storm- and non-storm-related work and the loss of critical information.

The team recommends the city take steps to further analyze the relationships between tree characteristics — size and species — and storm damage. In particular, it suggests further study of the interactions between size and species. The team further recommends the city consider assigning unique identifiers to each tree. The city’s tree census already provides an abundance of data, and public analysts could do more if the city were to record which specific trees crews attended to when completing work orders.