BROOKLYN EAGLE:

Dr. Suzanne Simard’s work on trees and their interconnectivity has been pretty monumental. I was wondering if you could speak on the importance of having her here at the Garden’s Gala on Tuesday.

ADRIAN BENEPE:

For background, the reason Dr. Simard is coming here is through kind of a chance encounter. Last fall, a Dutch landscape architect whom I know from prior work reached out and said, “Hey, would you be willing to help my friend Suzanne Simard and her co-author? They are working on a new book about the connections between people and trees, and she wants to come to New York and speak to the people who are responsible for the trees of New York, as well as the people speaking for the trees, advocating for the trees, and enjoying the trees.”

He reached out to me because of my background in the Parks Department, specifically leading the Million Tree Campaign under Mayor Bloomberg, as well as my current work at the Botanic Garden. There was a time when I was overseeing forestry and horticulture for New York City Parks. I know the world of trees in New York City and the people who are doing it, particularly the women who are doing it, because tree science and tree policy in the city are largely led by women, interestingly — almost without exception. Many of them are Yale University-trained forestry experts; there’s a strong connection between tree science in New York City and Yale University. Suzanne Simard is not from Yale. She was trained and did her graduate work in British Columbia, but she wanted to meet people here in the city. So we did three days of moving around the city together. At first, she wanted to see places like the Highline, urban greening projects, Hudson River Park. I took her on a tour, and she also wanted to meet with some of these officials, so I introduced her to the head of forestry for NYC Parks, a woman by the name of Jennifer Greenfeld. I introduced her to the head of the Natural Areas Conservancy, a woman named Sarah Charlop Powers — they both happened to be Yale-trained foresters. Jennifer Greenfeld is in charge of all the trees, horticulture, natural areas, and planning for all those things at the Parks Department. The Natural Areas Conservancy helps care for the natural areas, especially the woodlands of New York City parks.

There were others she met who help care for trees and fighting climate change. But I also said that she had to meet the Mother Trees of New York City, so I took her and her writing partner to Inwood Hill Park, which is home to the tallest trees in New York City. The tallest tree species in the city is the tulip tree, which is a native tree. All the tulip trees in NYC grow in the clove, a valley with steep hills on either side in Inwood Hill Park. It isn’t an exact remnant of pre-colonial time in the city, but it approximates it in terms of native trees. She had this encounter with these 165-foot-tall Tulip Trees, which are as tall as Redwoods on the west coast, and they’re many feet in circumference. She was able to experience truly the Mother Trees of New York City.

I also introduced her to the winners of last year’s Greenest Block in Brooklyn contest. We visited three or four of the winners and met the people of those blocks. That was fun. Each tree growing on a block is just as important as a mature tree growing in a vast national forest in Canada or the United States.

EAGLE:

I was curious about that. I don’t know if this is a question for her or you, but I was wondering, how do the underground root structures look different in a city than in a forest?

BENEPE:

That’s a good question and an open question, too. I’ve been talking to some people, like Sarah Charlop Powers, a great expert in the science of the forest of New York City. She has done groundbreaking research focused on carbon storage and cooling impacts in NYC. They’ve drawn some startling conclusions, one being that the 25% of trees in NYC in woodland forests in parks store 75% of the carbon. In other words, there’s a disproportionately positive impact of old-growth trees over smaller, less mature landscape trees.

And they found a similar conclusion in terms of cooling, that woodlands are cooler than any other kind of park, and native woodlands are cooler still. And they’re cooler by ten, maybe 15 degrees compared to surrounding neighborhoods and five degrees compared to parks like Central Park or Prospect Park. So there are two very important roles that trees play in cities, in terms of fending off climate change, cooling and carbon-storing. Trees won’t solve the climate problem by themselves, but they’re a piece of a puzzle. It’s pretty widely accepted now that planting big trees is a really effective tool in fighting climate change. And that’s a change. For years, while we appreciated big old trees, we didn’t understand their roles in climate change mitigation. We had a sentimental appreciation of big old trees and criminalized the public removal of trees, but now we have documentation of the positive impacts. And they’re now in the middle of researching the stormwater capture of green spaces and woodlands in NYC. That’s the third leg of three climate-related things they’re analyzing. But Sarah tells me that there isn’t any significant research done on mycorrhizal networks in urban spaces to the same degree that Suzanne Simard has done in woodlands and forests. So, I found one article saying that mycorrhizal networks did all these great things, but it seemed to be based more on speculation than actual scientific experiments conducted in cities.

I don’t know of any widely published research — even around the country — about this, and neither does Sarah. Point being this: when I see Suzanne, I’ll say, “Hey, have we got some research ideas for you! Let’s look at the mycorrhizal networks in urban areas or get some other research institution to do it.” As you know, in her book, she talks about the transference of nutrients and water between trees of the same species or even between trees of different species. So, when she was here last time, I had a speculative question for her. I mentioned the BBG’s collection of Pines on what we call Pine Hill. These pines are from the same family and come from at least four continents: North America, South America, Asia, Europe. All trees in the pine family are represented on Pine Hill.

EAGLE:

Back to what you were saying about same-species and inter-species tree communication, I was thinking as I was reading about last summer’s Power of Trees exhibition and the incredible diversity of trees that you guys have around the garden. I’d be curious to know how Dr. Simard’s work has changed how you and other conservation spaces plant and maintain trees, specifically regarding diversity.

BENEPE:

Broadly speaking, her research is groundbreaking. Every Botanic Garden has to think about it as they think about the long-term health of the living museums, which is a very important point. The BBG isn’t a park that happens to have some trees in it; it is a living museum of trees. For the most part, those trees are outdoors, so our collection lives outdoors as utterly dependent on or at the mercy of the elements. If we have a big storm, lots of trees can come down. Our hybrid oak specimen was almost split in half by a storm in 2019 but was stitched back together by arborists at the garden with help from an expert. So winds and storms can destroy our collection. Diseases, too. Currently, we are very concerned about the Beech Leaf Disease, which likely will eliminate our collection of Beech trees from the museum.

We have the problem of natural pests and diseases that are being exacerbated by climate change. As we get warmer winters, we can’t count on pest populations staying down. What happens when pests that don’t tolerate cold from a different country come to the city and are not met with winters that kill them off? We start to worry about trees that have adapted to colder climates or to temperate climates that get below freezing. Entire families of trees are at risk. The same way that Dr. Simard talks about the infestation of beetles in the fir trees in Canada that she believes was climate-related, which then led to lots of dead trees, which then led to the horrific Canadian wildfires.

EAGLE:

Are healthy forests less likely to burn?

BENEPE:

Yes, healthy forests are less likely to burn, but dead forests are incredibly flammable. The Canadian wildfires that came down to the city were prompted by climate change. We at the Botanic Garden are at the mercy of climate change, so we need to figure out what’s gonna happen a hundred years from now. The analogy I often use is that if we were at the Metropolitan Museum of Art and were told our collection would all suffer from heat generated by climate change and would start to melt in fifty to a hundred years, you can bet we’d have a plan for preserving the paintings, changing climate controls to make sure they don’t melt. But we can’t do that outdoors. Very few gardens can. Our living museum is at the mercy of the weather and climate change, which are two different things. You can have a cold and rainy winter and still be subject to climate change.

Extremes are often driven by climate change. So there are lots of things we have to know. If the elk bark beetle is racing around Prospect Park, we need to know how that applies here because our elms are threatened by them. One of our Beech trees is looking very bad right now. So, we need to learn about the potentially helpful impacts of mycorrhizal networks and the fungi connected to those networks, and should we be introducing certain fungi that could help the trees? But we don’t currently have the expertise to do that. We need the help of research partners. We’re currently in the process of doing a strategic plan centered around the question of whether the botanic garden should have scientific research, which we’ve had at certain points in our history.

EAGLE:

You mentioned that your staff was going to have the chance to speak to Dr Simard the day after the gala. Could you speak on the insight or opportunities she might bring to the garden moving forward?

BENEPE:

I think it’s great that we’re at least getting her thoughts. For example, we might ask how best to embark on doing research with a university. What would be the questions we should ask?

Clearly, she is one of the experts on Mycorrhizal networks — their impacts and potentials — so maybe she could help us find some preliminary research protocols. Her general knowledge of trees and tree science could be helpful in getting a sense of our plan for the next hundred years. For example, we would be thinking about how the next generation of trees could have to deal with hotter winter climates. In fifty years, can we have trees more commonly found in South Carolina? One day, will palm trees be growing? We might be forced into that. Having the attention of a scientist and advocate for a healthier planet, someone who has long fought for trees, will be helpful. Our whole garden is created by humans, and every tree is planted here purposefully. 

EAGLE:

Is there anything else you want to say regarding Dr. Simard’s visit?

BENEPE:

I will say that the trustees and staff of Brooklyn Botanic Garden are deeply moved that Dr. Simard agreed to be our honoree. She’s traveling a great distance to get here. She’s spending a lot of time with us and hopefully offers us some advice. But most of all, she understands that the purpose of the gala is to raise money. She said she wasn’t just here to receive an award but to help us keep doing what we do here. She understands that by being our honoree, she is being an ally to the 10,000 different cultivars we have at the garden. She’s a very generous person, and I would say that the person you hear when you read her book is very much who she is. She’s just as genuine, courageous, spiritual, and scientific about trees as she comes off in the book. She is that person. 

EAGLE:

What you were saying earlier about feeling both the sentimental value of trees and the scientific importance of them — she very much embodies that. 

BENEPE:

She understands that for the overall benefit of the planet, you need to understand what’s going on within the trees. She’s first and foremost a scientist, but she’s also a humanist who understands the existential relationship between humans and trees.