MS. DIANE REHMThanks for joining us. I'm Diane Rehm. What does a tree mean for a city? Author Jill Jonnes says more than you probably realize. It's good for our personal health and it's really good for the health of our planet. In her new book "Urban Forests," Jonnes explores the natural history of trees in America and looks at what cities today are learning about the value of trees in the modern urban environment. Jill Jonnes joins me in the studio to talk about urban forests.

MS. DIANE REHMAnd throughout the hour, I'm sure many of you will want to join us, 800-433-8850. Send your email to drshow@wamu.org. Follow us on Facebook or Twitter. Jill, it's good to see you again.

MS. JILL JONNESWell, Diane, it's great to be here in the city of trees, which -- so Washington D.C. has been famous for its trees, really since the mid, late 19th century.

REHMYou know, one of the things I left out in that introduction is what trees do for our mental, emotional health. I mean, when I see the trees here in Washington, you're so right, I mean, it just gives me a lift. I feel I can breathe more easily. I can enjoy the changing colors and here we are in October about to see that change and in spring, you've got the blossoming with this very, very pale, pale green. So for me, there is as much mental as physical health involved in trees.

JONNESYes. And that's not at all your imagination. I mean, one of the things that's been so interesting in working on this book is that we've had two urban tree movements in America. Not surprising, the first one happened as people began to move into cities. They were used to living in...

REHMExactly.

JONNES...environments with trees.

REHMRight.

JONNESAnd Washington actually was very -- the city was very specifically situated in a very beautiful forest with the expectation that a lot of those trees would be saved and therefore make it a -- not only a lovely place to live, but healthful. Before air conditioning, before modern medicine, trees were viewed as a very important aspect of public health because they kept the temperatures down. They absorbed the dust and they were viewed as somehow mitigating my asthmas, which contributed to things like malaria.

JONNESSo there are a lot of very famous early tree lovers, Thomas Jefferson was one of them. And when he came into the White House, he was infuriated because all around him in Washington, very mature trees were being rustled and cut down.

REHMRustled.

JONNESRustled meaning that people were stealing trees off of public land. They had all these trees that were there with the expectation that they would remain there as part of the general environment.

REHMHow did they do that? How did they actually take these trees and -- I mean, they had to uproot these trees.

JONNESWell, no. There's nothing like an ax. You know, Paul Bunyan. So you know, people just axed down large trees and you did in artful way and cut them up and that was a cord of wood. Many cords of wood.

REHMI see. You're not saying that they took them to transplant them.

JONNESOh, no.

REHMYou're saying they took them for their wood value.

JONNESYes.

REHMWell, the thing I worry about most here in the Washington, and certainly I don't know about other parts of the country, are the diseases that are affecting certain trees. You might talk about those.

JONNESYes. Well, so imported disease, pests and funguses and so forth, I mean, that's been going on for a long time. The first tree that disappeared was the American chestnut. The American chestnut blight got identified in 1904 in New York and it's a southeast tree, but it was really a giant of the forest, but also in cities. Cities, parks and woodlands were filled with huge, towering American chestnut trees. And it was a very jolly thing in the autumn. Everyone would go chestnuting.

JONNESThey would skip school and skip work. And then, all of a sudden, this blight appeared and it came from China, probably on some kind of nursery stock and it just ripped through, in two, three years, a chestnut tree would be -- I mean, 200-year-old chestnut trees just dead. And to this day, the blight is with us and it pretty wiped out the American chestnut by the 1930s.

JONNESSo it's not like these things happen overnight, but they move very steadily from state to state. So that was the first blight. And as I say, there's been a lot of work by the American Chestnut Foundation, but there's still -- you cannot grow a mature chestnut tree in America to this day.

REHMWhat about the oak tree?

JONNESAt the moment, I've heard rumors that bad things are happening with oaks out in California, but here in the east, we're fine. The really next major calamitous tree pest really was the Dutch elm disease. Again, came from China, wiped out the elms in Europe around the time of World War I. And it's called Dutch elm disease because the Dutch figured out what the fungus was and it's carried by bark beetles.

JONNESWe immediately put a quarantine on importation of anything live elms. However, we didn't put a quarantine on any kind of elm wood. And in the very late '20s, we began to get this elm wood veneer in the United States and the beetles and the fungus arrived with that. And so, in the '30s, everyone looked around and realized that this veneer had been shipped all over the country. Yeah. And I mean, I was talking about the enthusiasm as people moved into cities and we industrialized and wanting trees.

JONNESThe urban tree of choice, the iconic, beloved tree was the American elm. And so most American cities, by the '20s, actually have beautiful cathedral of shade canopies. And so when Dutch elm disease arrived, I mean, it was a whole other story than the chestnut blight for cities. And it started on the east coast in the '30s and it worked its way steadily west. It reached California in the 1960s and '70s. Now, unlike the chestnut blight, which wiped out everything, Dutch elm disease did not wipe out all American elms by any stretch of the imagination.

JONNESI mean, once I could recognize an American elm, and it's not that difficult, but I didn't know that much about trees before I started working on this book, there are still a lot of American elms left, big mature ones. And but many cities, 60, 70 percent of the tree canopy were these phenomenal mature elms.

REHMWhat about the maple tree, which is so common certainly here in Washington, but all over the country?

JONNESWell, I'm glad to say that maples are thriving and doing very well. And these days, there's a lot of emphasis on trying to plant native species because we've learned that they're wonderful for the environment and that birds and bees and insects need things to eat and so when you plant a native tree, you are nurturing lots of caterpillars and bugs and critters, which birds eat. So all's well with the maple. I should say that these days, having learned some lessons from monocultures of American elms, you try not in any city to overplant any one species.

JONNESSo what you find is you'll have cities that already have a lot of maple trees and so they won't be planting a lot of those because they've got really a good supply of them.

REHMHa. Interesting. You know, I certainly when my husband and I had a home with many trees around, we began to notice on our street these large caterpillar nests and one does wonder about the damage that those can do. They look like huge balls of cotton and they begin to grow larger and larger. I assume that those are, indeed, harmful to trees.

JONNESYes. Well, you know, trees, nature, it's a never-ending battle with everyone trying to win their fight. And I mean, actually trees themselves, every tree is kind of its own unique story of how it survives and tries to put out as many leaves and get more sunlight than the other tree. And so, yes. We would like to have trees that can nurture nature, but nature is engaged in its own ongoing battles.

REHMAnd what about global change? How is that affecting trees around not only the country, but the world?

JONNESSo one thing that's happening is apparently trees grow faster as there's more carbon dioxide that they're absorbing. But essentially as the world weather changes, people who are in charge of trees are trying to account for that. So as the world warms, as it gets drier, you try and plant trees that can survive that.

REHMJill Jonnes, her new book is titled "Urban Forests: A Natural History of Trees and the People in the American Cityscape."

REHMWelcome back. Jill Jonnes is with me. She's the author of a new book titled "Urban Forests: A Natural History of Trees and People in the American Cityscape." Her previous books include "Eiffel's Tower," "Conquering Gotham" and several others. Here's a comment from our website, which says, urban tree cover reduces the heat island effect through shade and transpiration and thus mitigates the effects of extreme heat. In addition, urban trees lessen the impact of local air pollutants. The number of trees won't be enough to offset the carbon dioxide produced, but it's still a small but important part of the solution.

JONNESYes, so one of the wonderful things that came out of the loss of elms was the realization by U.S. Forest Service scientists that many of the reasons that trees had been planted in the 19th century no longer existed. We have air conditioning, we have modern medicine. So how do you persuade city managers and bean counters that trees are not just an expensive, semi-necessary ornament?

JONNESAnd so a Forest Service scientist named Rowan Roundtree (sp?) decided it was going to be his life mission to train and pursue science -- train scientists and pursue science that would really be able to quantify the benefits of urban trees and translate them into dollar figures. So there were two really important scientists that carried this mission forth, Greg MacPherson (sp?) and David Nowak. (sp?) So this has been going on for almost 30 years now, and it really began to have significant consequences.

JONNESYou now had data that actually enabled you to know, you know, what the structure and function of your urban forest was. And I'll give you two quick examples of how that played out. One is here in D.C. There was a big story on the front page of the papers in 1999 about how D.C.'s urban tree canopy had declined from 50 percent to 35 percent. Philanthropist Betty Brown Casey saw that, and she wanted to endow a tree advocacy group, which is Casey Trees.

JONNESAnd so right there that figure motivated her to start a tree advocacy group. They in turn in 2002 did a tree inventory that showed that the city had 90,000 street trees, 30,000 empty pits, and that launched Casey Trees with a -- you know, with a whole set of data. They knew, you know, what kind of trees they had, what shape they were in. And today Washington has, as a result of not only Casey Trees but a really rejuvenated and topnotch forestry division here, there are 135,000 street trees. So you've had this big, huge improvement in this, in the tree canopy.

JONNESEqually impressive is what happened in New York City. So Greg McPherson went there, he did all this work, and in April of 2007, they were able to report to New York that the energy saving of New York City street trees, they have about 600,000 of them, was $28 million or $47 per tree. Each street tree absorbed 1.73 pounds of air pollutants, and they reduced storm water runoff by almost 900 million gallons. So a typical street tree was intercepting 1,400 gallons in storm water, and this was worth $61.

JONNESNow we all know that Michael Bloomberg, who was then mayor, is a very data-driven guy. He saw this data, he quadrupled the Forest Service budget there -- not the Forest Service, the forestry division, and he launched Million Trees NYC. So a typical city is doing well if it plants 10,000 trees a year. New York City has been -- they planted a million trees in not 10 years but eight. It was absolutely phenomenal, and it was all driven by data and knowledge and strategy.

JONNESAnd so, you know, I don't think most of us think of New York as a place where we're looking to for trees and for inspiration about trees and leadership, but there it is.

REHMThere it is absolutely. You will be interested in this email from Noelle, who says my grandfather was Joyce Kilmer.

JONNESOh my goodness.

REHMA number of people I know, she goes on to say, have said that "Trees" was the only poem they could remember.

JONNESSo Joyce Kilmer, turns out, was, in his day, a very famous poet. He was married. He had five children, and he wrote "Trees," and I think it was somewhat well-known. He went to fight in World War I, and he died, he was killed. And when he returned, there was -- this was the biggest war that America had participated in since the Civil War, and so the question was how to memorialize all these American military dead.

JONNESAnd there was launched, through American Forestry Association, known today as American Forests, and still here and very active and a great force for good here in D.C., I mean, they're just a force for good, but they're located here. So there was launched this incredible memorial tree planting all over the country to honor the World War I dead, and "Trees" by Joyce Kilmer was one of the absolute constant aspects of that.

REHMI think I can recite the first line. I think that I shall never see a poem as lovely as a tree.

JONNESCorrect, yes, and that poem was memorized, with the whole rest of it, by schoolchildren for Arbor Day from -- for years, for decades.

REHMStill in my head after all these years. Tell me about Arbor Day.

JONNESSo Arbor Day was dreamed up by J. Sterling Morton, who was out in Nebraska, and he was from Michigan. He was used to living around trees. And he got out to Nebraska, and he just looked around, and there were not enough trees for him. So in 1872 he launched this idea that you would have a holiday devoted to tree planting, and he felt this was a very American holiday because it looked to the future.

JONNESAnd Arbor Day didn't -- you know, I mean, a few other nearby states picked this up, but in 1882 the American Forestry Congress had its first meeting in Cincinnati, and they were really focused on the fact that we were clear cutting American forests. But the school superintendent in Cincinnati, a man named John Peasley, decided that he was really going to just absolutely go all out on Arbor but as a schoolchildren's tree-planting festival.

JONNESAnd he turned out 7,000 schoolchildren in this incredibly orchestrated event in Eden Park, and they planted up all different kind of groves that were very specialized. So there were authors' groves, and one of them was a presidential grove, which goes on to this day, and every president since that time has been able to choose the tree that they would like planted in their honor.

REHMHow lovely, really great idea. All right, let's open the phones. We've got lots of callers waiting. First to Madeline in Manistee, Michigan. You're on the air.

MADELINEThank you, Diane. I live in the middle of the Manistee National Forest. We have a 10-acre lot. And we're losing a lot of trees, well, the branches are all dying, and I haven't been able to find out why. But we've lost most -- almost 100 percent of the ash to the green ash borer. Beech trees have a fungus, and they're dying, mostly dead out in the area, including Traverse City. Birch trees have a borer, since 1950s we were fighting that.

MADELINEThe chestnuts you already mentioned, and Dutch elm disease, fruit trees all have those tent worms, and hemlocks are dying out in our area, and I'm not sure why. Oak has a gypsy moth and an oak fungus, and the pine root borer is killing pine trees. So what do you plant?

JONNESWell, I am not an arborist, and I would say that would be a question you'd have to put to your local forestry division. I do want to say that in response to just this proliferation of pests and diseases, a group of scientists have put together a legislative push called Tree Smart Trade. And of course like everything, it has a website, and they're actively working, actually with the Congress, to try and pass this.

JONNESAnd it's -- the two things that I would say are most important is it would end all use of wooden pallets, which is the way the Asian longhorn beetle got here and the emerald ash borer.

REHMAnd how are these wooden pallets used?

JONNESWell, they're what everything gets shipped within all these tens of millions of cargo containers. And the other thing is it would end the importation of any kind of live nursery stock. So people would say, oh, you can't ship without pallets. Well actually IKEA has, which I think is a huge global trading entity, has ended all its use of pallets and only ships with paper.

JONNESSo, I mean, it's actually really a big win-win because it's obviously a lot cheaper to ship something in paper, which is light, than to ship it in a pallet. So yes there's God knows how many wooden pallets out there that would no longer be used, and I'm sure there's a wooden pallet lobby, but we are in the middle of the biggest tree extinction or extirpation that we've had since the chestnut, and that is the emerald ash borer.

JONNESSo it's in 28 states, it hasn't crossed the Rockies. Full expectation that it will. One thing I should say to everyone who has a beloved ash tree, you can get it injected and save it. There have been cities that have gone this route because they, don't ask me why, but after they lost all their American elm trees, they then proceeded to plant monocultures of ash trees, and there are just horrifying photos of cities in -- out in the Midwest where before they realized they could treat trees, I mean, it always will take a few years to figure out, well, okay, so is there something we can put in a tree to save it, but just basically clear cutting in entire blocks and neighborhoods.

JONNESSo as I go out and talk about my book, I'm also talking about Tree Smart Trade because we live in a global world.

REHMOf course. Here is Steve in, pardon me, Detroit, Michigan. I gather you're an arborist, Steve.

STEVEYeah, I'm am arborist. I'm also on the board of directors of Releaf Michigan, a community tree-planting organization that replaces these trees as we lose them. I just mentioned -- the person who called in before had mentioned a bunch of diseases going on in Northern Michigan and then in Michigan in general. I just wanted to point out a lot of these diseases, as your guest had already said, was exotic pests, exotic insects brought in from Asia. The emerald ash borer epidemic started in Michigan, in Detroit, Michigan, and that was brought on -- brought in on shipping containers from China that released that bug, and now it's moved away across the whole Midwest and East Coast.

STEVEWe do have an Asian longhorn beetle that is attacking and killing maple trees in Chicago and New York.

REHMWow.

JONNESActually, I would like to just interrupt and say Chicago defeated the Asian longhorn beetle, thank you Mayor Daley. He went all out.

REHMReally?

JONNESYes.

REHMInteresting. Well, that's an update and a good one. And you're listening to the Diane Rehm Show. Now to Millsboro, Delaware. Hi Sandy, you're on the air.

SANDYHi Diane, how are you?

REHMGood.

SANDYI just returned from Jackson Hole, where I go every year, I've been going for 30 years, and all the devastation that you're talking about pales compared to what's happening in Colorado and Wyoming with the pine bark beetle. The estimate at this point is that by 2020, there will be no pine trees left in the Tetons or Yellowstone, and Colorado has already lost almost 15 percent of their trees.

REHMWow.

SANDYAnd it's a devastation because you talk about oxygen and CO2. There's no way for this to happen unless the scientists come up with something. Right now unfortunately the only two ways that it can be stopped is, A, by fire, which is very important because it's the only way the pinecones release their seeds, and the trees regenerate, or by 40-degree-below weather for three or four days, which is not going to happen. Does your guest have any feeling about what's going on with this or what can be done, or is anything being done?

JONNESWell, my book is called "Urban Forests," and honestly I really stick to that. I am not an arborist, as I say, I am not a forester, and again this is really climate change at work. I think people are very agreed on that. And what can you do? Again, I think you need to have a change of policies, looking to the future, and I'm assuming that these areas will have to be replanted with trees that can take warmer weather, less water and are known not to be susceptible to these particular beetles.

JONNESAnd they probably need to be, if possible, planted with a greater variety of trees. I mean, it's really tragic to see this kind of loss and the -- looking at the ash tree, which very much is an urban tree but is also very present in the forests, the prediction is that by the time the emerald ash borer is done, we will have lost eight billion trees.

REHMOh my.

JONNESYeah, the number of trees that are in a city, for instance, are really pretty mindboggling. One thing I want to -- I really want to be sure that we talk about here because such new science, and I think it's really the sort of the future of the way people think about trees. So I mentioned New York City and all of these what we would call ecosystem services, storm water, bringing down energy costs. But most people don't really care that much about that honestly.

JONNESI mean, you don't walk out your door and look at a tree and think I'm so glad it's saving money on our storm water bills. No, what people really understand intuitively and why, if you can live anywhere you want, you live surrounded by trees, I mean, all of this new technology and ways of intervening with the world or understanding the world really have changed what we know about trees and how we think about them.

REHMJill Jonnes and her new book titled, "Urban Forests: A Natural History of Trees and People in the American Cityscape." Short break here. We'll be right back.

REHMAnd welcome back. Lots of people have been talking about the trees out in Indianapolis, where a huge property has been sold with 300-year-old trees on it, and they're all slated to be cut down.

JONNESOh, horrible.

REHMAnd the question is how do you put a price, a value on those trees so that those who are against cutting them down can make their case more forcefully?

JONNESSo this is the beauty of what is known as i-Tree. And that is the software that enables you to make use of all this incredible forest service science. So there is a -- it's a free public domain software. If they can get in touch with some arborists, they would be able to help them. You -- i-Tree stands for Inventory of Tree Resources, Economic and Environmental. And by going and doing some measurements on those trees they will be able to figure out how much storm water those trees absorbed. How much they cool things down.

JONNESBut that's actually, as I was saying before, probably not the most compelling aspect of this. They can definitely make a dollar figure of the incredible importance of these trees, economically. But there's this whole public health aspect of trees that's been emerging in recent years, which is really about how important and essential trees are to our well-being…

REHMExactly.

JONNES…as humans. And so for instance, there's a forest service economist and researcher out in Portland. And he got really interested in this issue. And his name is Jeffrey Donovan. And again, all these big data sets make possible this amazing new science. And this work that he did actually has also been replicated in California, in Spain and in France. And he was looking at birth outcomes. So you have addresses for women who are pregnant.

JONNESYou can look at, you know, tree canopy maps. And then you can figure out where the trees are. You then look at the birth outcomes and what he found is that you could, controlling for all other things, show that women who have, you know, proximity to trees, have higher birth weight babies. And his response to this was the results suggests that natural environment may affect pregnancy outcomes and should be evaluated in future research.

REHMHow fascinating.

JONNESSo big disaster with losing all the ash trees. And Donovan thinks, gee, this is a great research opportunity. We'll flip this on its head and see what happens in all of these states where you're losing hundreds of millions of ash trees. And this is, you know, documented. And you have a lot of big data sets for these counties in these states. And what he was able to, you know, learn from that was that in 15 states, the (unintelligible) was associated with an additional 6,113 deaths related to illness of the lower respiratory system and 15,000 cardiovascular related deaths. And what he found was that there was a bigger effect in wealthier counties because of course there are more trees there.

REHMMore trees in wealthier counties.

JONNESRight. So Donovan has taken to saying, trees quite literally can mean -- be a matter of life and death for people.

REHMIndeed, indeed. But if you've got a private developer who has purchased a parcel of land, how much voice can the community bring against cutting down all these trees? I mean, some are gonna say, well, you get more taxes from the sale of this land, the cutting down, the construction, the rentals or the sale of properties. I mean, that's where the rubber hits the road, literally, that you've got to simply impress upon legislators the importance of trees.

JONNESYes. And you're very lucky here in the District of Columbia, because Casey Trees has really made it its business to advocate for exactly this issue. And they've actually just strengthened the tree removal laws. So if you are a private property owner in the -- in D.C. and you have a tree above a certain size, you cannot just willy-nilly take that tree down. I mean, yes, if you can show that it's diseased and a danger you have all right to take it down.

JONNESIf you just are taking it down for your own purposes, then you have to pay basically a fee for that right. Because you are removing something important from the overall urban forest. And the urban forest is collectively providing all kinds of eco-service benefits and also health benefits to the whole community.

REHMExactly. All right. To Jennifer in Cleveland, Ohio. Thanks for joining us.

JENNIFERYes, hello. Thank you for taking my call.

REHMSure.

JENNIFERYes, I'm the city forester for the city of Cleveland in Ohio. And we've got about 120,000 street trees that we maintain and manage here in Cleveland. And there's just one thing that Ms. Jonnes said that I just was hoping that I could clarify or perhaps ask her to qualify the statement about treating ash trees. That's a -- I just wanted to kind of point out, especially here in Cleveland, not all ash trees are candidates for treatment. And so if a private owner or even a municipality does have an ash tree population, I strongly suggest having them contact and ISA-certified arborist to find out. Have the ash tree evaluated and assessed and see if it is a candidate for treatment.

JONNESYes.

JENNIFER'Cause certainly we don't want to put chemicals out there that are unnecessary and we certainly don't want to, in our industry, put our reputations on the line promising something that can't be delivered.

JONNESYes, and thank you so much. That really is excellently stated. The fact is that at a certain point if an ash tree is badly infested, that's it. It's done. But…

REHMWell, and we have an email from James, who says a tree expert from the city parks department came to our civic club and told us by the time the average citizen can see a tree is in trouble, it's too late. If you have trees you love, you should have an arborist look at them yearly. Jennifer, I would presume you'd agree with that.

JENNIFERAbsolutely. And it's important also that they have the ISA credential, which stands for the International Society of Arboriculture.

JONNESYes.

JENNIFERSo yeah.

JONNESSo I just do want people to realize that if they have a beloved ash tree, and the emerald ash borer is in their state or is gonna be coming to their state, that they do -- that they should be aware that they can save their tree if they take steps in time.

REHMAll right. Let's go to Liz in Takoma Park, Md. You're on the air.

LIZHi. The reason I'm calling -- and this addressed to the author obviously -- is I went forestry school at the University of Washington. And the -- this is your moment to sell the book as a history of urban trees and forests. I'm kind of wondering if -- it's reading like a science, economic-type text to me. And I was wondering if you…

JONNESNo. There's a lot of love for trees.

LIZYeah, I'm wondering if you address, you know, like the Ellises or the Olmsteads or the various, you know, the evolution of urban trees and how designers…

JONNESYes, they're all there.

LIZBecause that's not what I'm getting out of that.

JONNESOkay. Well, then let me fix that. Because, no, the book is full of these wonderful characters. John Davey, who invented arboriculture, and whose company, The Davey Tree Expert Company, to this day is around and is very much a force in urban forestry. And actually helps host, essentially the I-Tree software. Charles Sprague Sargent who started the Arnold Arboretum, which, again, is around to this day and is a, you know, very important source of being able to just look at the whole history of trees.

JONNESYeah, I'm really pushing the science and what we've learned because I want people to understand that our appreciation of trees in cities today, in order to have these things funded and for people to really appreciate what trees do, I just want people to be aware of I-Tree and this science. Because I think it really changes the way people think about trees. However, I'm with you. I don't personally need to know those things because I can look at a tree, in the same way that Diane was talking about at the beginning. Trees are just esthetically beautiful and that is really, in the end, what most people are responding to.

REHMYou write about David Fairchild. Tell us about him.

JONNESSo David Fairchild is really one of my favorite characters in this book. He was a plant pathologist who worked for the USDA and became a great explorer. And eventually had this wonderful title, tree -- no, not. Plant Explorer-in-Chief at the USDA. And he…

REHMPlant Explorer-in-Chief. I like that title.

JONNESYes. And he himself went all over the world learning about what was available in practical ways in other countries. And was responsible for bringing to the United States, all kinds of fruits and vegetables and trees. And he dispatched various -- very famous explorers, including a man named Frank Meyer, the Meyer Lemon. And he -- and David Fairchild was married to the daughter of Alexander Graham Bell.

JONNESAnd I think for many people in America, the thing that they would feel bonded to David Fairchild over is the Japanese ornamental cherry. So you just have to remember that once upon a time there were no such trees in America because they were all in Japan. And a woman named Eliza Scidmore went and fell in love with them in 1885. And she basically spent 23 years trying to persuade Washington bureaucrats that they should plant cherry trees.

JONNESAnd it was when she allied herself with David Fairchild, who was just a man who swooned over these cherry trees and filled his estate, which is what is now the top of Connecticut Avenue, with 25 different kinds of cherry trees. And he would go out very early in the morning and study them and take photos of them with the dew on them. So he just loved cherry trees. And when he and Eliza Scidmore got together and connected with Nellie Taft, the first lady of the time, she instructed the bureaucrats that they should start planting cherry trees.

JONNESAnd they -- the bureaucrat responded, well, I have put American elms there. And Nellie Taft said, remove them. Anyway, the story of the cherry trees is very famous in Washington. But the more important thing that Fairchild did, working with Charles Sprague Sargent at the Arnold Arboretum was to get those trees and their seeds and so forth out to the commercial nurseries. And I think it would be widely agreed that there is nothing people love more than those ornamental Japanese cherry trees.

REHMYou're listening to "The Diane Rehm Show." And finally, to Rochester, N.Y. Hi, Jason, you're on the air.

JASONHi, there. I wanted to bring up the idea of how important it is to plant both native and non-native species. We're seeing a lot of local, regional and state efforts to plant native species on streets and private areas, etcetera. And we don't really live in a native world anymore. And so I think beyond -- you've got to -- we've got to push the curve here beyond just monoculture. Let's get past monoculture. But then we've got into, you know, really extreme diversity. Because we don't live, you know, we live in a global world. So we have to plant that can survive lots of different things. And I think one of the big things that's hurting diversity is the local pushes for, you know, native -- specing out native trees for replanting.

JONNESYes. Well, I think that that's -- I'm right with you there. I personally happen to love gingko trees for a variety of reasons. One, it's the oldest known living continuous plant. You can see fossils. It existed before the dinosaurs. It's in a class by itself as a tree. They're very recognizable to people because of their fan-shaped leaves. And in the autumn, what is more beautiful than the gold of gingko tree? They also are the only tree that has moving sperm that fertilizes the fruit.

JONNESSo you get the fruit of the gingko tree, and thanks again to the amazing world we live in, you can go on YouTube and watch this photographed or videoed and see it. In the old days, you had to patiently wait and hope you'd see it looking through a microscope. So the great thing about gingko trees, is they've outlived pretty much everything that would ever bother them.

REHMWhy are they so resistant?

JONNESWell, they've outlived their predators, pretty much. I mean, they are an extraordinary tree. As urban trees, unfortunately they're sort of expensive because they've very slow growing. The faster growing a tree is the cheaper it is. And I do want to give the good news that the American elm is back. So the irony in, you know, especially in the Midwest, so they lost their elms. That was just a tragedy.

JONNESThey replanted with American ash in many places. Now, they're losing their ash. And of course, they're trying not to plant up with monocultures. And again, variety is everything here. But you can plant the American elm now. And on my street where I live, where we lost all our elms, we have a big variety of trees, but among them are these new American elms. And they grow like weeds and they're beautiful.

REHMOne caller we didn't have time to get on the air, from Durham, N.C., says he and his wife moved from Oklahoma to North Carolina. And the difference in how urban trees are handled is astounding. Which leads me to the final point about how there needs to be a national appreciation of the importance of trees, rather than some regions take good care, others do not bother. And therefore you get these various blights.

JONNESYeah, so, I mean, really, I wrote this book because I wanted people who are very intuitively aware of trees and who love them just innately to understand where we are today and the possibilities.

REHMFinal email from Chuck. "One thing I notice more now is the sound of trees and how trees affect a soundscape. I've come to appreciate white noise in the city." Lovely comment. Jill Jonnes, she's the author of a new book titled, "Urban Forests." Thanks so much for being here.

JONNESThank you. And I should say as I sit in this studio, I look out and see the beautiful tree canopy of Washington, D.C.

REHMIsn't that wonderful. Thanks all for listening. I'm Diane Rehm.