2015 Street Tree Census Report
One City | Five Boroughs | 666,134 Trees

TreesCount! 2015 is the third citizen participatory inventory of street trees in New York City. Every ten years, NYC Parks has worked with volunteers to record the location, size, species, and condition of all public curbside trees. Volunteer street tree inventories promote increased awareness of the importance of the urban forest and support municipal urban forest management. New York City’s prior street tree inventories in 1995 and 2005 led to advances in customer service, funding for routine street tree pruning, the quantification of the ecological and economic benefits of trees, and a major urban greening campaign called MillionTreesNYC.

From May 2015 to October 2016, over 2,200 citizen mappers spent almost 12,000 hours using high tech mapping tools with survey wheels, tape measures, and tree identification keys to create a spatially accurate digital inventory of NYC’s street trees. The simple and intuitive mapping method was designed by a local non-profit, TreeKIT. The mapping technique leveraged a municipal geospatial dataset of curb edges to solve urban locational accuracy issues. The data collection method was integrated by the software company Azavea into a web application featuring online training modules, event management and community engagement tools to provide a seamless volunteer experience. The TreesCount! user experience was designed to scale for thousands of non-technical volunteers to collect standardized and consistent data with minimal training. To inspire public engagement, the web app featured real-time inventory metrics for individuals as well as partner community groups, and a progress map on the status of the data collection campaign. Powered by the public, TreesCount!2015 demonstrated that citizen science can support the collection of high quality spatial data for municipal urban forest management and ongoing citizen engagement.

Data collectors recorded eleven variables on each tree which included biological, structural, and infrastructural information. To learn more about each variable collected in the census, click here.

TreesCount! 2015 was the third decadal street tree census, and largest citizen science initiative in NYC Parks’ history. The 2015 census attracted 2,241 active volunteers, more than doubling involvement from the 2005 census; with the largest increases in participation seen in Brooklyn and the Bronx. The results of the census show that there are 666,134 trees planted along NYC’s streets, of which volunteers mapped and surveyed 225,595 (34%).

One of the recruitment strategies employed by NYC Parks in 2015 was to leverage existing relationships and build new ones with partner groups to reach individual volunteers. This strategy resulted in the involvement of 64 community groups who collectively mapped over 15% of block edges in the city. These groups ranged in size from large groups like the Prospect Park Alliance and the Lower East Side Ecology Center, to smaller groups like the Sunset Park Block Association and the Jackson Heights Beautification Project. The ten community groups with the most participants are noted in figure below:

NYC Parks also worked with US Forest Service social scientists at the NYC Urban Field station to survey volunteer census participants. Just over 27% of volunteers responded to the survey. The survey indicated that volunteers were students, retirees, tourists, taxi drivers, artists, and engineers, among many other backgrounds. For many respondents, volunteering provided them with a link to nature, taught them a new skill, or gave them a chance to explore their neighborhood and their city. Additionally, 59.6% of the volunteers that responded to the survey had never volunteered with NYC Parks before, and 46.9% had never worked with trees. We also learned from the survey that at least 11 participants in 2015 also volunteered in the first census in 1995.

NYC Parks also studied the quality of the data collected by different categories of census participants. The emphasis of the volunteer training was for participants to feel comfortable using their training and survey resources to make their best educated guess. Volunteers were also reminded that NYC Parks had a data quality process in place to identify spatial inaccuracies. In addition to volunteers, NYC Parks also hired and trained data collection staff in order to complete the census. To learn more about the data quality assurance process, and how volunteer-collected data compared to data collected by dedicated NYC Parks staff, check out this report.

Click here to read more about volunteer training events, which took place throughout the course of the census.
Check out what motivated volunteers to count trees.

Did You Know?

  • The top five individual volunteers mapped a combined 35,995 trees, or 5.4% of all the street trees in NYC.
  • Volunteers walked 3,615 miles, equivalent to walking from New York City across the Atlantic Ocean to Madrid.
  • Volunteers donated approximately 11,123 hours to TreesCount! 2015, saving the city about $100,112 in tax dollars.
  • While more than two-thirds of volunteers resided in NYC, they also hailed from Long Island, Westchester and 15 different states across the U.S.
  • Volunteers mapped trees almost as accurately as dedicated Parks staff (96% accurate).
  • 70% of volunteers who completed the volunteer survey said they felt more like a part of their neighborhood.
  • There were 12 volunteers who traveled to all five boroughs to map trees.
  • Williamsburg, Brooklyn was the one neighborhood in NYC that attracted volunteer mappers from all five boroughs. See this on a map!
  • NYC Parks acquired 890 survey wheels for the census.

Volunteer Testimonials

The 2015 Street Tree Census showcases technological advances across several dimensions, emblematic of a forward-thinking, transparent and community-oriented Parks department. The most notable differences from past efforts involved the baseline geospatial data, methods for mapping trees, and techniques for mobilizing volunteers and tracking progress. We also used technology to check the data for accuracy after it was collected. And the final deliverable of the census— the web map giving the data back to the public and updated daily for education, stewardship, and general awareness—is the enduring product of this high-tech vision for urban forestry in NYC. We also shared all of our datasets—from 1995, 2005 and 2015—with the public through the NYC OpenData portal so that anybody can analyze and learn about changes in the street tree population over time. Together, these technologies facilitated an enormous citizen science engagement project, a spatially precise street tree map, a living web application for public engagement in the urban forest, and a comprehensive dataset for anybody to download.

NYC Parks contracted with a software company, Azavea, to develop a responsive web application for digitized data collection and project collaboration. The code for this application is available as open-source software on GitHub. The elements of the web application, designed for use on (name types of devices), are as follows:

  • Data collection and mapping methodology. Over 90% of the census data was collected using a mobile device. The neighborhood-based participatory mapping and data collection methodology combined site surveying methods and geospatial technology to derive the location of street trees with a high degree of accuracy. The user-centric mapping method was designed by a local non-profit, TreeKIT, and integrated into a mobile-first web application created by Azavea. The mapping methodology itself solves several problems related to the accurate mapping of street features in urban environments where GPS doesn’t provide sufficient locational accuracy and is designed to scale for a wide variety and large number of non-technical users to collect standardized and consistent data with minimal training. The application, called TreeCorder, allows users to walk city blocks, recording the locations of trees and distances from the curb-line. Tree data was collected along blockedges, which were most often the strip of sidewalk between two intersections, on one side of the street. TreeKIT’s geometry constructor places each tree along each block face from the GIS base layer, at the distances the user specified in the TreeCorder.

  • Mobile Reservation System. In order to collect tree data, participants first had to reserve blockedges via the TreeCorder. The participant would sign in to the app and navigate to a map of all of the blockedges in the city. The map showed which blockedges were available for data collection, and which had already been collected. Users tapped each available blockedge they wanted to map, and the application added the blockedges to their queues. Once blockedges were reserved, they were shown as “unavailable” on the citywide map to prevent duplicate data collection. Community groups had a two tiered reservation system, by which swaths of blockedges were reserved for collection only by those associated with the group. In order for a participant to access these community group’s blockedges, the group leader had to grant access to the user to make reservations in that group’s zone. The majority of participants went through the two-tiered system, though independent mappers were able to reserve and map blockedges anywhere in the city.

  • Integrated collaboration platform. In addition to supporting the mapping methodology the TreesCount! Web application also supported community engagement and communication through online training, event registration and management, block edge reservation system, and live street tree count metrics and progress map. The platform supported individual volunteers as well as local organizations who committed to recruiting volunteers and hosting events to map specific sections of the City.

          Click the screen on the TreeCorder to see more!

Our hard-working street trees are in constant service to the people of New York City. They absorb gaseous air pollutants, provide cooling summer shade, and offer pastoral natural beauty amid the concrete jungle. By surveying street trees, we can collect baseline data on the state of a population in order to track changes in this population in the future.

Check out how far we've come