Episode 8: Seeing the forest and the trees

Today marks the eighth and final episode of season 1 of Remarkable Objects (sob).

Since this podcast is all about the intersection of nature and the urban environment, I wanted to use this last episode to talk about engaging ordinary citizens to create a better urban forest. As much as policies and regulations shape our cities, it’s the human affinity to nature – that essential, foundational connectedness – that explains why we care.

So today, we’re sharing a story about the biggest city in the United States, New York City, and how it recruited thousands of its residents to take a census of the city’s street trees – over half a million in all. Our guest is Jennifer Greenfeld, the Assistant Commissioner of Forestry, Horticulture, and Natural Resources for the New York City Department of Parks and Recreation. Her job is to manage, think about, and plan for nature in New York City.

After the 2016 census was completed, the Parks Department turned all the data they gathered into something shareable: a public-facing interactive, living map. The map shows every single tree along the city’s sidewalks and streets, displaying the species, size, and ecological benefits of each at the click of a mouse. Users can favorite trees, record a care activity (like watering or mulching), and report problems.

It’s a simple idea, but the map does something out of the ordinary: it invites the public to interact with their urban forest in a totally new way.

Listen to the episode in iTunesSoundCloud, or Google Play.

Thanks for listening. And stay in touch!


Leda Marritz | Creative Director, DeepRoot.

TRANSCRIPT: Seeing the forest and the trees
GUEST: Jennifer Greenfeld (New York City Parks Department)


The goal of the census is really twofold. It’s not just about getting the data, but it’s about using the data gathering need that we have for the city to engage people, because we’re in a city, you know? We’re managing these trees for people and around people. And so our management approaches always consider people and consider ways we can engage people in caring for trees, and noticing trees, and advocating for trees, and planting trees. So, even if we could do it with staff, we couldn’t imagine completing a census without volunteers.

I’m Jennifer Greenfeld, and I’m the Assistant Commissioner of Forestry, Horticulture, and Natural Resources, and I work for the New York City Department of Parks and Recreation. The way I describe my job is I think of it as managing, thinking about, planning for, nature in New York City – in all the places you find it.

This is Remarkable Objects, a podcast from DeepRoot about the intersection of nature and the urban environment. I’m Leda Marritz.

This is the last episode of our season, and to close it out, I wanted to talk about engaging ordinary citizens to create a better urban forest. As much as policies and regulations shape our cities, it’s the human affinity to nature – that essential, foundational connectedness – that explains why we care.

So today, we’re sharing a story about the biggest city in the United States, New York City, and how it recruited thousands of its residents to take a census of the city’s street trees – over half a million in all. Over a period of about 18 months, Parks Department employees and over 2,000 citizen volunteers literally took the streets, using surveyor’s wheels to precisely locate every tree, and smartphones to record data about condition and species. They released the results of the census at the end of last year.

New York City has actually conducted two other street tree censuses prior to this one. In the past, the data that was collected was used only by the city. But this time, they turned all this data into something shareable: a public-facing interactive, living map. The map shows every single tree along the city’s sidewalks and streets, displaying the species, size, and ecological benefits of each at the click of a mouse. Users can favorite trees, record a care activity (like watering or mulching), and report problems. It’s a simple idea, but the map does something out of the ordinary: it invites the public to interact with their urban forest in a totally new way.

What type of data was collected in this census, and did that differ from either of the previous two that were done now 10 and 20 years ago?

We collected really some basic information: species, size, condition. We looked at if, sort of the growing condition, if there were things that were kind of, um, inhibiting the trees from growing – whether there were blocks in the tree bed, we looks at tree guards, sort of fencing around trees to see if they were damaging or if they were beneficial to the tree. We looked at all of those in the last census; we actually collected more information in the last census, and we found that we didn’t really use it all, and it was sometimes confusing to volunteers. So we really simplified the types of data that we collected.

But what was really different about this census that we weren’t able to do before is we collected very precise location information about each tree.

Oh really? Why weren’t you able to collect that before?

So in the last census, the way you knew where the tree was that you basically looked at the address of the building in front of you. So you said, “Oh, it’s in front, or it’s on the side, it’s the second tree to the left of this building.” And if you were in front of a lot it had to be, you know, “OK, we’ll take the address of the adjacent building and associate it with that,” so there was definitely a system, there was a very clear protocol, but it was all relative to another stationary object that we could identify.

So of course things are completely different now, you know everybody has GPS on their phones, and you know, digital maps are really ubiquitous. So it seemed like we needed to do a better job of locating these trees.

So what’s really different is we partnered with a group that had actually a very community-driven effort to influence the way we did the census this year. So they’re a group of people who experimented with a system – the group is called Tree Kit – that experimented with a system of using a surveyor’s wheel. So you know, you see these people with basically a wheel with a stick at the end of it, you can walk along and measure distance with this wheel.

So you take this, you know, pretty simple machine, as they would call it, and you walk it down the block. And you start at a very specific spot, and you stop every time you get to a tree, and you record the distance, and then you move on. And this group identified a way of turning that information of these very simple measurements, into a very precise map of where the trees are in space.

Once they solved the issue of how to locate the trees precisely, they needed to find a simple and easy way to collect the data while out on the street. They worked with a second company called Azavea to develop a custom app that could be loaded onto a tablet or phone. This is what volunteers used to record information about each tree as they worked their way down a block.

So as you’re walking with this wheel, we call it, actually, people say you’re “rolling the block,” so as you’re rolling the block you stop, and you enter that distance information into a tablet. And then the information that we collect is about species, size, and condition, into the tablet right there. And then you keep on rolling down the street, and you do the next tree, and the next tree and the next tree, and then at the end of the block you click a button and it gives you a preview of what you just measured, and it’s overlaid over top of a satellite image. So you can right away say, “Oh yeah, that looks good, I did three trees kind of close together at one end of the block, and then there were a couple more further away.” And you get this real-time data fed back to you, and then you click “OK, that’s good,” and then you go on to roll your next block.

So this is interesting, because what you’re saying is that the major innovation for this census wasn’t the incorporation of smartphone GPS systems, it was the use of an inexpensive but highly precise measuring device that’s been around for decades.

Correct. That is true. We used a physical object to create a very precise map. The precision is really important. GPS, they’re usually plus or minus several feet. But that doesn’t work for a tree, because some of the trees are 20 feet apart, 25, 30 feet apart. But where they are in relationship to everything else out there really matters, and if you lose that precision of two or three feet, every single time you have a tree along a block, it adds up quickly.

So, this is much more precise than what you can get in a basic, commercial GPS unit. And we’re not talking about a few thousand trees, we’re talking about 666,134 trees that we measured, and it’s a huge, HUGE job to do all this. And it’s just not practical to use GPS to pinpoint the location of every tree. And this other method was low cost, and simple, volunteers could use it – it was very easy to describe and very easy to implement.

This is over half a million trees we’re talking about. How many citizen volunteers did you work with?

We had over 2,200 volunteers participate in the census, and that’s more than double than we had 10 years ago.

So did most people do a block, or an afternoon? I don’t know whether to visualize these contributions in terms of geography, or time, or what.

Yeah, I mean, it’s incredible. There were some people who just did a few blocks… First of all I’ll say the volunteers collected 30% of the census, so they did a lot. We had a lot of staff do it as well, but they did a significant amount.

We just had an event where we recognized the top five volunteers. There is one woman who did 10,000 trees! I mean, it’s incredible – every weekend, I’m sure. And she did it in multiple boroughs. And then the other of the top five did 7,000 and 5,000 trees, I mean… Some of these people were extremely dedicated. There are some volunteers who worked every single season, who collected data through the winter. We did special winter workshops for volunteers who wanted to do that. There are volunteers who went to all five boroughs and, you know, they’re not all accessible by public transportation, and not everybody has a car in New York City. So, they really had to go out of their comfort zone to explore different neighborhoods.

You talked about training people to ID tree location. But how did you train them to assess tree condition and species?

Yeah, well, we definitely had to train them to do that! But we kept it very simple. We had a really beautiful tree species identification, almost poster-sized, that you could open up and help you narrow down the species based on the shape of the leaf and some other characteristics. There are probably 100 different species on this piece of paper – I’m sort of flipping through as I’m talking to you. And the guide has photos, really just beautiful photos of every single leaf that helps you identify the tree. And we trained them how to use it and how to look for specific characteristics for each of the trees.

The conditions that we established for trees were good, fair, poor, and dead. Very broad categories, and we recognized that they are volunteers who are doing this. So while we establish criteria for each of those broad categories, we, you know, don’t make absolute assumptions that it’s exactly right. So it gives us this great snapshot of how well our trees are doing – and they’re doing very well – but we do have to say, just because a volunteer said it, said a tree was dead, doesn’t mean we’re going to run out and take that tree down. We always would have a professional go out and take another look at it before we act on anything.

What did you find was motivating to volunteers? Why did people choose to contribute to this project?

Um, that is a great question. I wish I had a real answer. I mean, my thought is there’s the volunteers who have been interested in trees for years. They love trees, they were in the last census – actually there are some volunteers who did both censuses, all three. So there’s just this constituency of people who love trees, and they care for them, and they report it when there’s a problem, and they’re just used to being in this community of tree lovers. So there’s folks out there like that.

There are people who are into technology and mapping, and I think this time around we really attracted some of those folks.

People who really care about their neighborhoods. You know, we reached out to a lot of community groups, they may not be focused on trees. It’s their neighborhood that they really care about, and they’re involved with it, so here’s another way of learning about their neighborhood.

I mean we also, you know, last time we didn’t have these volunteer events. So we tried to make it more of a social activity where people are meeting up to volunteer. So I think there’s also a social element of it for the folks who came to all of the events.

Why was it important to turn this volunteer effort into a public map that displayed the collected data?

Well, I guess there are number of reasons.

Over the last 10 years, we’ve really tried to engage the public in caring for trees. We have workshops where we teach them how to care for trees, we go into neighborhoods where we’ve really planted a lot of trees and recruit people, and block associations, to do projects. And one of the things they like to do, and we like them to do, is record the work they did.

So, how do you get them to record? They could send you a list, or they could go to a map and say, “Oh, here’s my tree, and I planted flowers in it this year.” So we tried to give people a map of their trees so they could tell us what they were doing. Like I was explaining, it was based on pretty faulty data, and the volunteers were very frustrated. They said, “I got to my map and my tree wasn’t there, it wasn’t in the right place.” And so this what we called “adopt-a-tree” map was, like, just barely good enough. So we knew that if we were really going to be serious about engaging people, we needed to give them a better platform to work on.

So that was one motivation. And we wanted to be able to tell people about trees and to be able to give back to volunteers who cared, who collected the data. And it sort of helps us in a selfish way because this way, if they give us information back, like “we think this tree needs to be removed or has an issue,” we’re getting the exact tree they’re asking for.

So up until now, someone calls 311 and they’d say, “OK, it’s the tree on the corner of 2nd Avenue and East 34th Street, around the corner from my house…” And this, the operator has to figure out how to, you know, write this down and send it to us. And we go to the corner, and we think we know what they’re talking about, but it’s not always obvious. So this helps us too because we’re getting much better information back from the public.

There has been a strong initial public response to the map – which is a positive start for a project that was designed, in large part, to engage citizens. In the first six weeks after it launched, nearly 2,000 activities were reported (that’s an average of over 300 per week!). Over 1,200 trees were favorited, and 667 people registered as users on the site. In addition, at least 80 requests for care have been submitted through the site’s “report a problem” button.

The map is constantly being updated with new information based on these citizen activities and requests. In fact, the Parks department actually integrated the census data directly into their own management database. They now have a centralized system where census data and tree care activities administered by the Parks department are combined. The map is a way of visualizing and sharing the information that is used to manage New York City’s urban forest every day.

It also seems like a validation of the value of trees and the role of Parks in caring for those trees to have this information be public, and to um, express this value of citizen engagement that is so essential to the project.

Yeah, it absolutely is about citizen engagement too, because trees are… they’re… You know, most people don’t necessarily notice them, right? They might notice that they’re walking on the shady side of the street on a hot summer day, but they’re not necessarily absorbing the fact that that shade is coming from a big, leafy, growing object that’s growing out of the sidewalk. And that somebody is thinking about and caring about that tree every day.

So the more that we can make those connections with the public, the more they’ll support the effort that we put into caring for the urban forest, and the more they’ll help us protect them.

Do you think the map will result in better care for the city’s trees?

I think so. I think the map will help us do a better job at reaching the trees that need care, I think it’ll help us do a better job of communicating what we do to the public, which helps them sort of support and back up what we’re doing. So the map can do all of those things.

Is this part of a larger shift to a culture of analytics and data? Is that the direction that the New York City Parks Department is going?

Yeah, I think so. I mean to me, this is where we are. We’re always going to learn new things as time goes on, technology will change, but to me this is a huge achievement and we need to just make sure that our back end is clean and we can be transparent about the work we do on the front end of the public-facing map.

Do you think data helps change the story about why investing in trees is good for communities and entire cities?

There will always be a tension between trees and the other sort of demands on what I consider real estate, right? So the sidewalk is a piece of real estate; there’s only so much space for it. Do you need to have driveway access? Can’t have a tree there. Do you need fire hydrants? Do you need an ADA-accessible ramp? So there are all these things that compete for space within this very limited real estate. So there’s always going to be that tension.

I think the data can help up move the needle a bit in terms of building more advocacy and awareness for trees and what they provide.

But with an… how do I want to say this? Without an awareness of the benefits… If you don’t go into this sort of negotiation with an awareness of the importance of the tree and what it provides, then you’re not going to get anywhere. So I think this helps us move the baseline a little bit higher. So you’re going into it at least with an awareness, at least with a sense of what the benefits are, and building the advocacy a little bit stronger.

So we do certainly hope we can move the needle on that.

What do you see as the function of trees in a city as huge and as dense as New York?

In New York City we have some beautiful old forests that people aren’t really aware are there, and coexisting with over 8 million people. But then on the other side of the spectrum is this street tree, which is kind of that gateway drug to nature, right? It’s the first thing they see when they walk outside their building… and it should ideally lead them to the park, and to the forest.

I don’t know exactly how to express it, but they’re working in the background all the time, and I’m just hopeful that this effort can help make those connections to all kinds of nature in New York City, not just trees, but starting with that street tree.

According to the 2016 census, there are 12.5% more trees in the city than there were when they were last counted. And there’s still room for a lot more. Jennifer said there are more than 200,000 planting spaces that are currently empty where trees could go. To play around with the map for yourself, check out the link in the description for this episode.

Remarkable Objects is produced and edited by me, Leda Marritz. You can find us online at remarkableobjects.com, and on Twitter (@RemarkableShow). This podcast is a production of DeepRoot Green Infrastructure. DeepRoot provides landscape solutions and technical support services to promote mature tree growth and sustainable stormwater management in the built environment. Find out more at deeproot.com.

That’s it for season one of Remarkable Objects. Thank you SO MUCH to everyone who listened, shared episodes, rated or reviewed the show, and otherwise showed us support. This has been an incredibly fun and interesting project, and we are so appreciative of everyone who helped make it happen. We’re not sure yet when we’ll be back with more, so if you want to stay informed follow DeepRoot’s @rethinktrees Twitter handle. Again, thank you for everything!


Broke for Free, “Golden Hour”
Blue Dot Sessions, “Rafter,” “Discovery Harbor”


  1. Remarkable indeed. I have no idea of where else I can find such leading edge, progressive, beneficial perspectives on our urban forests as this series and the resources of the DeepRoot site as well. Thanks!

  2. That living map idea is amazing! It’s such a great idea to have the city residents come together to map all the trees and monitor their activity or the activity of others toward them. It really is important to make city councils aware of the importance of trees. Congrats to NYC for the 12% increase in the tree population.

  3. It’s a good idea, the trees make a significant difference to climate as well. I generally work around inner city areas, however I live on top of a mountain range in rainforest area. The difference in climate is around 5-20 degrees cooler, so getting home in the afternoon is a nice way to relax.

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