The Truth About Trees

Did you always know your book was going to be called Seeing Trees? It’s a beautiful title.

It was about showing people multiple perspectives on how trees in the city have been understood. At the same time, I wanted to show how people have quite literally seen trees. In the late nineteenth century, early urban foresters were advised to use an optical device called the dendroscope, which would allow them to cut tree crowns into a symmetrical shape and to apply that shape to multiple trees. Even though it’s not clear whether the device was ever actually used as such in urban environments — it would have been labor intensive — there are many references to and recommendations for its use. The book is about looking at this individual, living object, but it also tries to put it into context.

When you’re super stressed about other things and you walk in the city, you don’t really look at the trees, you don’t even look at the plants around you. There was an article in the early 2000s on what some scientists called “plant blindness,” which they found especially in children. Basically, an alienation from nature; but they also found that kids couldn’t recognize a single species anymore.

Yes! I made a Tree Museum to celebrate the centennial of the Grand Concourse in the Bronx in 2009. I visited a school on the edge of Joyce Kilmer Park, and there were two gorgeous Amur cork trees and lots of evergreens right outside the school. But one of the teachers was just seeing “tree” everywhere. I said, “go look around and you’ll see they’re kind of different.” We met up a week later, and he was like, “Oh, you were right, they’re all different!”

“A tree is a tree.”

That just blew my mind. I grew up in rural Ireland, where there was a very cyclical, simple connection between what you had on your dinner plate and where it came from and where the compost would go.

And what got you into art and trees?

I came to New York City on a Fulbright scholarship specifically to look at nature and our relationship with it in the city. It only took a few months before I started to internally feel… “Concrete jungle!” I was in the East Village and realized that my only contact with living things that weren’t humans was with street trees. I started making very simple drawings, mapping my walks using the street trees. I recognized later that they were like love letters, the trees were communicating.

Were you making those drawings on the basis of your imagination, or what you had seen?

A friend gave me a present of a little field guide to New York City trees, because everyone associates me with trees and plants! I’ve used the same book since. They have little silhouettes that show the trees, to help ID.

My work’s not just about trees. It’s also about language between and beyond humans, and the problems we have with language. The Tree Alphabet project came out of my thinking about that. Words like “nature,” “green”: What do they even mean? I don’t think we know anymore. Words lose their meaning, we confuse the word for the thing.

Ten years after making those first tree drawings, I understood that I can actually use them to write with. The trees are “characters.” I sat down with a piece of paper: A, Apple; B, Beech. The whole project is very simple.

So many things about your Tree Alphabet and the tree font remind me of the struggles around actual street tree planting. Trees have to be planted at a certain distance from one another and from nearby buildings, from utility lines. The space needed depends on the species, but also on the environmental conditions, and, of course, on the desired effect. I could imagine that in working on the tree font, you may have had to think a lot about the right spacing for each tree. It’s the same in tree planting!

Exactly. How do you translate trees from the “wild” to the city street? It was always apparent to me that the font speaks to, or for, city trees rather than natural planting in the wild. When creating a font you have to think a lot about the scale, spacing and kerning; it’s like cultivating and pruning.

In your Tree Alphabet, some tree species are small, some are wide, others tall or narrow. In contrast, in your tree font, every tree is the same height or size even if the forms are different and they need different amounts of space. To a certain extent you had to standardize the symbols. It was the same when trees were begun to be planted systematically along city streets. They had to be forced into shape to have a desired effect, to fit into available spaces, but also to create space.

Robert MacFarlane, the British writer, shares a word every day on Twitter. When he posted about crown shyness, with a photograph illustrating how trees tend to leave enough space so all the branches can get sunlight, like they’re shy, it really resonated with people. So that was in my mind: how much should the trees touch each other?

So I opened up the conversation to people on Twitter and shared an image with three options: the trees touching, trees with a little space, and trees with more space. Most people liked the middle one, where the trees have a little space to breathe.

There are the needs of each species and there is the question of how near trees can stand to buildings. And also, what should the space be between individual trees? The space in the ground counts as much as the space in the air. In the late 19th and early 20th centuries street tree experts were already very concerned about the contestation of space.

I love your Berlin stories. There’s a real sense of grappling for space. After World War II, trees were painted to mark the border between East and West. When they weren’t able to prune street trees, they blocked sunlight, so people were in the dark.

Even today, you find many of the same complaints about trees. In early 20th-century New York City, seeds clinging to the clothing of passersby was a very big concern. Or caterpillars falling down on people who were sitting on benches. Washington D.C. has a huge number of ginkgo trees lining the streets. The ginkgo is very resilient in urban environments, and people like the glowing yellow color of its leaves in autumn. But female ginkgo trees produce seeds which, when they fall onto the ground and especially when they get squashed, smell really awful. Since the 1940s, Washington’s urban foresters have used chemicals to prevent female trees from producing fruit. Some years ago, they began injecting them underneath the bark to prevent the trees from flowering and developing seeds. Of course, this can also go wrong, because they can miss the environmental and physiological conditions that are necessary for the growth regulators to have the desired effect – they can miss the cycle. You can draw these parallels between human bodies and trees. So, I think in 2008, they missed the cycle and had seeds nevertheless. That caused a huge disaster.

Nevertheless, they persisted! When I was working on the Tree Museum, some kids told me how awful trees are. They wanted to chop them all down because they couldn’t see their friends from their windows or from the park; trees block the view, they get in the way when they’re playing football. Trees are bad, that’s what the kids thought.

Even after the Second World War, people were making arguments for getting rid of trees in the city, because they were obstructing vehicular traffic. At a time when cities were being built for and adapted to motor and private automobile traffic, when basically everything was about speed and development, many argued against trees in the city.

In your book there’s an incredible photo of a street with no trees, and it says, “a typical New York street.” To me that doesn’t look typical, it’s terrifying. I physically respond to the image. There’s something so wrong with it.

At certain moments before-and-after images showing streets without trees and then with trees were published to illustrate the positive visual and psychological effect trees could have. Photo collages were also made for this purpose. But many business owners did not want street trees because they thought they would obstruct street signage, advertisements, and window displays.

In the book, I sensed a constant shift between the positive economic aspects of trees, and the rich fat cats saying, “We don’t want them because they block,” as you say, “the signage.”

Social scientists have undertaken studies and have come to the conclusion that actually street trees do enhance commerce.

You don’t have shop owners or store owners anymore saying, “No trees”?

Probably there will always be business owners who do not want trees in front of their stores. But research in certain contexts has clearly shown that it’s beneficial.

What interests me is the evaluation or even monetization of the intrinsic or immaterial benefits, if you will, of the trees. Already in the 19th century scientists were trying to rationalize and measure subjective feelings around trees: What is it like to stand in the shade of a tree, how much can a tree cool the air through the gas exchange that occurs in its leaves? Today trees in many contexts are first and foremost considered providers of “ecosystem services.” But although we now have incredibly sophisticated systems to measure trees’ climatological functions, we still don’t really know how to account for their social and cultural values. These are just too difficult to measure and monitor.

One of the things I always noticed when I visited New York City was that there were some treeless streets, and that it’s incredibly difficult to maintain street trees on some of these streets because they get so little light and have so little space. Take Fifth Avenue, for example, in its downtown and midtown sections it is treeless until you come to the Rockefeller Center.

And then all the other problems as well…

So little space for the roots, and so much traffic.

Even though the model tree city in the US is actually Washington D.C., New York City became a model beginning in the 1930s, ‘40s, in the sense that many cities in the U.S. began to inquire about how New York was maintaining its trees. Basically they were saying, “Well, if they can do it, we should certainly be able to do it!”

Did foresters in different cities exchange tree species lists with each other?

This would probably be difficult to do given the varying environmental conditions. But in the 1970s some German tree experts did indeed suggest that exchanging tree lists between different climate and vegetation zones could help cities to tackle planting urban heat islands, for example. Climate change is also causing increasing changes in the selection of species for our cities today. Many countries and cities are testing species and new cultivars that have not been planted in cities before.

How did you select the species for your New York City Tree Alphabet?

It was important that the trees be part of the city’s official planting lists, current and future, so that we can use the Alphabet as a planting guide. Every tree has a story. We spent months sharing the tree list back and forth. Xanthoxylum came when I was out visiting one of the Parks stewardship teams. When I told them that I still didn’t have a tree for “X” one of them said, “Oh, Xanthoxylum, the toothache tree!” It’s also called “tingle tongue” and was used by the Lenape to help with toothaches because chewing on the leaves or bark creates a tingling, or numbing effect.

For a long time American Beech was “A” because Ash trees can’t be planted anymore. The Emerald ash borer beetle has decimated hundreds of millions of trees in North America. But when I visited Edward Toth at the Native Plant Center on Staten Island he said: ““A” has to be Ash!” The plan is that eventually, at some point in the future, we’ll be able to plant Ash trees again.

The city’s planting lists are changing with the climate, so the alphabet includes non-natives and species that are going to be planted in the future. I kept calling them “new species” but they’re not new, just new to here. It’s political, so I had to be careful in how it’s worded — some people get alarmed if they hear about “non-natives” being planted. But, basically, the Tree Alphabet creates an accessible way to think about climate change and how the city is adapting.

Because of climate change, those who for a long time were arguing against non-native species have changed their minds; botanical cosmopolitanism is becoming more accepted. But these are old and recurring conflicts. Andrew Jackson Downing, a famous nineteenth-century landscape gardener, first promoted the ailanthus, the tree of heaven in New York City. All of a sudden around the 1850s he became very skeptical and then condemned the ailanthus, arguing that it’s a foreigner on native soil. His prose is very discriminatory and racist. The shift in his assessment can only be understood against the background of the nativist and anti-immigrant sentiment of the Know-Nothing movement.

Planting trees is political. Years ago I worked a lot with weeds. I always loved weeds, they’re basically just something that’s growing in the wrong place. But who’s to say it’s wrong?

The ailanthus was considered a weed.

Right. There was an ailanthus at the southern end of the Grand Concourse, and I had to fight to include in the Tree Museum. The Parks Department said, “It’s not a real tree, you shouldn’t include it.” But it was gorgeous. A big, beautiful tree growing right out of a house. They couldn’t remove it because it would’ve cost tens of thousands to take away. For me it was important because it’s there, and you can’t pretend that it’s not there.

One of the reasons why there seems to be this age-old, human affection for trees is that they’re truthful. In your book About Trees you have a lovely essay on the witness tree, and also the cores of the trees. Trees can’t lie. Obviously, you can manipulate them. I show in Seeing Trees how street trees are the results of techno-scientific progress, they’re manipulated. But because of their greater permanence than human lifetimes, trees also are these truthful living beings that everybody can relate to. Especially in today’s times, trees appear to be something that people can hold on to.

Trees can’t lie. I love that! And the time factor, too. Trees can live for so long.

One of the things that I find interesting is the relationship between private and public. Who plants the trees? In New York City, street tree planting was always a private-public partnership. The Department of Parks and Recreation sometimes had more to say than at other times, but it has at most times been dependent on private support of some kind. Whereas in Berlin, it’s the city who takes care, and it doesn’t want the public to mess with the street trees. In the last decades public funding has no longer been sufficient, so it has recently also been seeking private sponsorship for new street tree planting. But the only thing that the Berlin city government will call upon the citizens to take care of is watering street trees in the summer. No more than that. They’re afraid that citizens will do some bad pruning.

So they don’t have citizen pruners the way we do here?

No, they don’t. The citizen pruners initiative is very interesting because it also encourages the connection to nature, which we’re losing. Perhaps it is a bit easier for people in Berlin to access public green space because the city is not as dense and large as New York.

What form will the NYC Tree Alphabet take, or what are you currently envisioning?

The first phase of tree planting with the NYC Tree Alphabet will happen in April, hopefully. We’ll select the messages, or love letters, from submissions people send us. Bram Gunther, co-Director of the NYC Urban Field Station and my mentor while artist in residence, realized that we should probably first do some test plantings in large parks or forested areas. That way we’ll have time and space to invite groups of people join us and we can see how different planting options might work best. Then we can move to street trees later when we know what we’re doing.