Recorded Webinar: NYC TreesCount! 2015

Coordinating a street tree census in the biggest city in the United States is exciting and challenging. Jacqueline Lu, the Director of Data Analytics at NYC Parks, discusses how NYC Parks developed and conducted TreesCount! 2015. Deborah Boyer from Azavea describes the software used to gather the data and how digital tools can assist with large-scale urban forestry data collection. We received a lot of great questions during the webinar and have compiled answers to some of the most common questions below. 

Is the TreesCount! 2015 software available for other municipalities?

TreesCount! is an open source project and the code is freely available at Software development experience will be needed to set up the code, and the mapping process relies on the existence of a file of street block edges for your city or town. For groups without the technical capacity or budget to set up the code, OpenTreeMap may be another solution. OpenTreeMap is a cloud-based platform for helping groups map trees, track stewardship activities, and engage the community around caring for the urban forest. Although it does not include the event management features available in TreesCount!, it does support volunteer mapping as a citizen science initiative.

Why did NYC Parks conduct a volunteer-led tree inventory? Was TreesCount! more expensive than hiring an independent contractor?

NYC Parks’ goal was not simply to collect tree inventory data. From the project’s inception, they also focused on encouraging citizens to engage with the urban forest through the census. If the goal was to get data only, it likely would have been more cost effective to hire contractors to use satellite imagery to plot trees or complete an on-the-ground tree survey. NYC Parks’ focus on citizen engagement was central to the design and functioning of the software Azavea created for them.

Azavea team members volunteering with NYC TreesCount! 20145. Azavea team members volunteering with NYC TreesCount! 2015.

Are ecosystem benefits incorporated into the data?

The TreesCount! software does not calculate ecosystem benefits. After the 2005 census, NYC Parks’ ran the gathered inventory data through the U.S. Forest Service’s iTree Streets (formerly STRATUM) and they plan to complete a similar process with the 2015 data. The software platform for TreesCount! was focused on supporting Parks’ staff, individual volunteers, and partner organizations in their effort to inventory trees. The data was collected so that little manipulation is required for upload into iTree Streets and other analysis tools.

Were there areas that volunteers could not survey due to concerns about personal safety or data quality?

Before sending volunteers into the field, NYC Parks identified block edges where they thought there may be access issues or that would be challenging for volunteers to survey. Challenges included but were not limited to the location of the street, the direction of the street, and the existence of trees in a median. These areas were set aside for volunteers with advanced training or NYC Parks staff. There were also instances where expert surveyors visited a site and determined that the area was too dangerous to survey (example: trees located on a narrow median on a multi-lane street). The project excluded private streets, which fall outside the Parks’ jurisdiction.

How did NYC Parks encourage safety while mapping?

NYC Parks’ encouraged volunteers to map in pairs and groups, and all volunteers wore bright green vests designating them as a volunteer surveyor. Mapping events were often co-sponsored by partner organizations familiar with the area and were generally accessible via public transit.   

How did NYC Parks’ deal with naturally occurring or self-seeding trees?

TreesCount! 2015 was explicitly focused on mapping planted street trees located along street block edges. The surveying methodology worked well for single trees along streets and was not as well suited for gathering data on groups of trees that may appear due to natural regeneration.  

One of the thousands of blocks volunteers inventoried during TreesCount! 2015.

One of the thousands of blocks volunteers inventoried during TreesCount! 2015.

What does the NYC Parks define as a sign of stewardship?

A sign of stewardship is defined as evidence that a tree received tending or maintenance by someone. This can include tree guards, signs of proper pruning, flowers planted in the tree bed, and mulching. These categories of stewardship were taken from a study NYC Parks completed in 2006 on the effect of stewardship on tree growth and mortality. The study concluded that visible more signs of stewardship for a tree often resulted in greater longevity for that tree, especially when the tree was younger or newly planted.

How were volunteers trained?

Before mapping, all volunteers completed an online training and then received field training from NYC Parks staff or a partner organization. Training materials can be viewed online at

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