Urban Forestry: Native Species & Climate Change

Sam Heywood, area manager for Davey Resource Group (DRG), talks about urban forestry and answers listener questions about planting native species in urban environments and how climate change is affecting the species we plant. 

In this episode we cover: 

• What is DRG? (0:48)
• Tree inventories (2:01)
• How did Sam start working at Davey? (3:55)
• Why should we have trees in cities? (4:45)
• DRG's impact on urban forestry (7:17)
• Listener questions
  • Ecological benefits of native trees in urban environments (9:08)
  • Tree that provide ecological benefits in urban environments (15:42)
  • How do Davey arborists plan to keep the benefits of urban forestry alive throughout the years? (17:53)
  • Lifespan of urban trees (21:20)
• DRG's work to help cities with their trees (22:35)
• Sam's favorite trees (24:17)

To find your local Davey office, check out our find a local office page to search by zip code.

To learn more about DRG's work with urban forestry, visit our webpage, Urban & Community Foresty Services. 

Connect with Davey Tree on social media:
Twitter: @DaveyTree
Facebook: @DaveyTree
Instagram: @daveytree
YouTube: The Davey Tree Expert Company
LinkedIn: The Davey Tree Expert Company 

Connect with Doug Oster at www.dougoster.com. 

Have topics you'd like us to cover on the podcast? Email us at podcasts@davey.com. We want to hear from you!

Transcript

Doug Oster: Welcome to the Davey Tree Expert Company's podcast, Talking Trees. I'm your host, Doug Oster. Each week, our expert arborists share advice on seasonal tree care, how to make your trees thrive, arborists' favorite trees, and much more. Tune in every Thursday to learn more because here at the Talking Trees podcast, we know trees are the answer.

I'm joined by Sam Heywood. He's an area manager for the Davey Resource Group based in Colorado. Today we're talking all about urban forestry, and we've got a couple questions from another certified arborist who has questions about urban forestry. This is going to be fun. Sam, welcome to the show. Tell me a little bit about what the Davey Resource Group is.

Sam Heywood: Thanks, Doug. Thanks for having me and thanks for having us as I am representing DRG, Davey Resource Group today. Davey Resource Group, and specifically, Davey Resource Group Environmental Consulting, is the consulting specific side of Davey Tree. We focus on tree inventory, strategic planning, development consulting, municipal consulting, anything in that realm. Think the side of Davey Tree that sticks more to our tablet computers and things more than the chainsaws and the operations it takes to do the tree care itself.

Doug: You're based in Colorado, but are you traveling to do this work?

Sam: These days, not so much. I lead our front-range based team here of consultants. In my history with Davey and with DRG, I'm in my 13th year, I spent a majority of that traveling around to municipalities doing tree inventories and consulting around the country, outside of the country as well, up in Canada. Covered a lot of ground in those years.

Doug: If you could just give me an example of a tree inventory. This might be too complicated for us, but if you could simplify it, what does that mean? What are you doing when you go to a city and they say they want you to do a tree inventory?

Sam: Right. In our world, increasingly data-driven, we are armed with those tools, like a tree inventory, to better inform the city and whoever's managing the tree population with that information. In our current methodologies, we have two distinct ways of doing this. One we call traditional, and that would be a boots-on-the-ground inventory where an arborist is going up to each tree, measuring diameter, identifying the species, potentially a condition rating, a primary maintenance, all kinds of different data fields depending on the municipality or developer or property owner there.

We also have our smart tree methodology, which in a nutshell amounts to scanning via a car and potentially using a point cloud to collect data on the tree through a means of technology, and then perhaps verifying via arborist review. In either case, there are paper inventories out there, but 9 times out of 10, this ends up in a GIS software. You're looking at a map similar to Google Maps, and you're seeing the trees as little dots or other symbology there provides which trees need maintenance more quickly or more readily than others and other things like that.

Doug: That's absolutely fascinating. Now, I've talked to probably 100 arborists, and 90% of them have the same reason for what they do: We want to work outside, I wanted to be a forest ranger, I love trees. How about you, Sam? How do you fit into this? Why is this job right for you?

Sam: Yes, definitely that was part of the components. I came onto Davey Research Group doing ground survey work in woodlots and then moved into this municipal work. A lot of time spent outdoors, staying close to the field, sharpening my scientific skills, but applying those in a way that is practical and helps these communities and these other entities.

Doug: Our topic is urban forestry. Let's first talk about the importance of our urban forests. I think it's pretty obvious we want urban forestry. We want more trees in the city. Just tell us why. I think we already know, but we want to hear it from you.

Sam: Yes, we've seen some good reception in recent years to conversations with the public, with policymakers, people outside of the industry viewing trees as assets. Anyone in the industry is thumbs up on that. We know that these things are working for us, just as any other asset in the city would do. Park benches, street lights, anything, roads, these are assets that are growing, that are developing. Having up-to-date data on what these trees are doing for us and how we can better maintain them, that's where urban forestry finds its niche and covers that ground.

Doug: Am I wrong to think that, and this is just what I'm thinking, urban trees, I'm thinking it's got to be some of the toughest varieties that there are, or is it just dependent, as we would in any landscape, right tree for the right place?

Sam: Yes, definitely right tree, right place takes precedence in any of these situations. There are cases in which, despite regionality or where a tree might have been natively located, hey, this is a super salt tolerant tree or something like that, and that is best suited for this urban landscape. This tree's bark is really thick, or some way it's deflecting the sun scalding or things that we see have increased reflectance from surfaces, these are tough trees in tough growing conditions as opposed to the natural landscape.

Doug: There are certainly beautiful varieties out there, and these trees are performing a lot of important jobs in the city, right?

Sam: Absolutely. In addition to beauty, there's things that we might not think of in urban trees, like food forests, providing sources for habitat of the animals and things that are in the urban landscape as well. Beautification, of course, environmental impacts increased due to the amount of gray infrastructure, so concrete and things like that, where these trees are up-taking stormwater, reducing heat island effect, all that good stuff.

Doug: Before we get to the questions, I have to assume this must feel really good to be doing this, to be figuring this out and to be trying to help whatever it is, a site, a city, whatever you're working on, good feeling, right?

Sam: Definitely. I think having the impact on a macro level when it comes to larger projects or larger clients like a municipality. Through our planning, we write plans that are 20-year visionary plans. We do inventories that guide the decisions that are made in the coming years. We have that ability to educate and provide best practices at a pretty high level. Also, when we're on these smaller projects, we're making those more tangible, right, think more of a traditional arborist role where we're looking at a single tree and we're saying, hey, we should preserve this tree because of the importance to the site or to the community around it as well.

Doug: Looking from the outside, for the bigger projects, to me, it seems daunting. [laughs] When you're talking about 20-year project, not only daunting, but a lot of responsibility.

Sam: Yes, for sure. When we write those plans, we're talking with as many different groups that have input, the community, the development, to make sure that those policies and guidance that we're putting forth make the most sense. When it comes to inventory work, you look at that map and you say, well, we're in the northwest corner of the city, and in three years' time, we will make it across the city or we're doing those scans, we'll do the whole thing and we'll come back the next year. It is a large volume of work, but you chip away at it and you finish your block and you're onto the next one. It is a good feeling.

Doug: Yes, it sounds pretty cool. You ready for the questions? They're long.

Sam: Yes, absolutely. Yes.

Doug: All right. We'll go to the explanation and then the question. Here we go. I'm an ISA-certified arborist and landscape designer working at an architecture firm in Atlanta. I do a lot of design work in the urban environment as well as permitting with the city arborist regarding tree preservation and replacement. "I have two questions that I'd be interested in hearing from Davey. In municipalities for cities such as Atlanta, the tree ordinance and requirements makes planting native species a priority.

75% of trees in a planting plan must be native to the Piedmont region of Georgia. He says that he prefers native trees in my designs, but I question the idea that even 50% of the ecological benefits, especially with wildlife and insects, are attained from planting a native species on a busy street surrounded by buildings, cars, and hardscapes. These type of ecological benefits likely need to coexist with ecological environments of the native areas of these trees, not an urban city environment.

I'd be interested in hearing from Davey outside of stormwater mitigation and reduction of urban heat island effect, which can be achieved with non-natives," he points out, "if the actual ecological benefits of specifically native urban tree plantings can be achieved in these environments, either not native to the US or not native to the specific region where plantings are taking place? If so, what tree species have you seen achieve ecological benefits in urban environments and how?" Sam, that was a mouthful. Did you understand all that? Because about halfway through, I'm getting lost. [chuckles]

Sam: There's definitely some pieces we can highlight here and some really compelling trains of thought. I really appreciate the question, for sure.

Doug: Break it down for me a little bit on what you're thinking when you hear all that, because I think from a listener's standpoint, their ears are going to start to glaze over about halfway through that question. What are we looking at here, basically? What do you think the issue is?

Sam: I think one asterisk to provide, or maybe this is actually a benefit to having me take this question, I have not personally worked in the Atlanta market, but I have worked in similar ordinance-heavy municipalities, Austin, Texas, where the cities have these strong tree ordinances that require specific planting plans or perhaps mitigation on private property when tree work is occurring or removals are occurring.

I think the first thing that our listener had here about this requirement of native trees at a percentage level is an interesting thing to point out, where they talk about how this contrasts with the ecological benefits, wildlife and insects. I hear, hey, does a native tree specifically provide habitat for the other native wildlife? Does it still do that once you put it into a tree well in front of an apartment complex or you put it in a parking lot outside of a building that's being built? Outside looking in, again, probably not. I look at it this way. Why does the city of Atlanta ask for 75% of those trees to be native?

It might come from a different source where its perception or its local character or its known ecoregion as those being safe trees. It's hard to have a native tree, I'm sure there are some somewhere, be an invasive tree, or maybe that line shifts over time. A quick answer is, well, native tree, we know it probably does pretty well here. It probably isn't going to cause us a whole bunch of headaches. Let's go with that. I think there's an emphasis on the benefits being put here, but again, there's other things to be considered besides those ecological benefits.

Doug: I think in general, and I don't know how Atlanta made this decision, but in general, over the last 10, 20 years, people have been taught natives are good, so let's put them in. In my case, in my personal landscape, I'm replacing oak trees with natives. I think I'm doing the right thing. I don't have any data telling me that my American hornbeam is going to be a positive, but I want diversity in my forest. It is an interesting question as to why we have to have 75% natives. Again, without any scientific data, to me, that sounds like a great idea. Okay, natives, we know that they live here and that the wildlife relate well with natives.

Sam: Yes, it's certainly entered the public vocabulary of native trees, the importance of native, the lack of invasives. We find that a lot when we do outreach for our planning efforts that there's often an attendee to a public meeting that says, "Well, we're going to put in a native-only planting plan forward. We need to make sure that is occurring."

I think it's often thought as in contrast to greater biodiversity where, and as we talked about a little bit ago, success of a tree, doesn't matter where it's from, but this is a salt-tolerant tree in maybe a northern half of the US environment, or this is a really successful tree in an arid landscape where we know cityscape trees are potentially underwatered, overexposed to heat. Oh, no, it's not native to this, but that's the situation that that tree is going to be living in.

Doug: Certainly, it's going to be different for Atlanta than it is up here in the northeast or out west. You're going to have certainly different choices of species, but also completely different weather conditions. The last part of the question, "What tree species have you seen achieve ecological benefits in urban environments and how, over your time doing this?" Can you answer that question?

Sam: Again, it varies region to region. I think an interesting point on this question, I did do a quick look at what Atlanta puts forth on their code. Not only did I find this specific 75% should be native species language that the listener listed here, I also found some information about removal of invasive species. They did note that in Atlanta, removal of an invasive species still requires the permitting process, I should say. What that sounds like to me is that there is an importance, even if the tree is invasive, that there's benefits that those trees are providing. I think that's maybe the newer way of thinking. We've got this all native all the time, and then this native plus non-native trees.

There are good things that an invasive tree would be doing. At just a very high level, there's a loss of benefits of the removal of a tree despite it being invasive. Depending on where you are in the country, there's trees that are providing ecological benefits, even though they might be on the bad list from the ordinance or anything like that. I liked seeing that in the code. It contrasted to maybe that more traditional thinking of native percentages.

Doug: Let me ask you this, did you answer the question? [laughs]

Sam: Not in a way that was listing a number of species that provide ecological benefits in the urban environment.

Doug: It's not black and white. When I hear you answering that question, there's a lot of thought going in there, and it's not black and white. Are you ready to tackle the second question?

Sam: Sure. Absolutely.

Doug: I hope the listeners are because I have not shortened these. I want the question to be exactly as it was sent. "On a related note, I'm constantly trying to pick, predict the right trees for urban conditions that will not only live now, but will continue to stay alive and hopefully thrive well into the future. We all know that urban trees have shorter lifespans and limited growth potential due to urban stressors, but climate change and shifting hardiness zones will likely accelerate the stress and continue to push species out of their normal hardiness zone if we are only thinking of what survives in the present day.

If we continue to replace urban trees every 15 to 20 years, we are not gaining the many benefits that large canopy trees can provide cities. What have Davey arborists who work in urban areas observed around this subject? How are Davey arborists planning for trees that are resilient now as well as 50 years down the line?"

This sounds like another one that's going to be tough to answer, but let me just throw something out. When I talk to all these arborists, there's concerns about certain types of trees with the change in our climate. Sugar maples would be one. Sugar maple for us in the east here is one of the number one trees. It's a great shade tree, great fall color, but there are worries in 25, 50 years how that sugar maple will do depending on how the climate changes. When you see that question, what are you thinking?

Sam: I like the emphasis on longevity here. I think that's key. The listener is correct that when we look at i-Tree or similar benefit modeling, we see the majority of those benefits realized from our largest trees. Largest trees take the longest time to fully mature or be in those larger size classes. On the timeline of replacing trees every 15 to 20 years, the development and the climate change is outpacing whatever natural amount of establishment or even what nursery propagation could probably accomplish with getting these trees ready for this.

In our work with municipalities and some of the things that I've heard talking to nurseries, it is bringing those climate-ready trees, either stock or saplings, or raising the seeds locally from those higher-numbered hardiness zones, so further south. Here in Colorado, it's maybe New Mexico, things like that. You bring those up. You try and extend the lifespan of what we think of the urban forest as a whole by mixing in those trees. Going back to the first question, those, I guess, could be considered non-native as their present hardiness zones.

There's the gray area in this, again, where we're seeing what is native, what comes up here, how often are these lists updated, who's got purview over these lists? Proactively planting trees that are at those higher-level hardiness zone numbers from south moving up, it's a step in the right direction.

Doug: When the listener says, "15 to 20 years lifespan for an urban tree," is that something that you've experienced or that you've seen or what do you think?

Sam: I think outside of the tree's survival itself, there's the pressure of development and how often do we repave or how often do we repair sidewalks that prune into roots that maybe shorten the lifespan of a tree that would have been okay given urban environment, given urban stressors, if it continued to receive the care or lack of care that it has, it would be okay? That shortened span is exacerbated by development occurring repeatedly on a site and I think importance of tree ordinance and tree protection, things like that. I hope we get more time with our trees than 15 to 20 years, especially those that are larger and can provide those benefits once they've reached those larger size classes.

Doug: Let's finish on a positive note. [laughs]

Sam: Sure.

Doug: Talk about the good work that you're doing, whether it's a smaller project or an entire city, to help them with their trees. We all know more trees is a good thing for us, for breathing, for stormwater, whatever it might be. Trees are a positive. Just talk about the good part about that. From a scientific basis, what you think?

Sam: I think some of the stuff I've been really proud of us recently is review of these ordinances and in partnership with the City and other groups that are interested in what those codes say, bringing them up to industry standards, bringing them up to standards that are reasonable for all the players involved. That's where I find a lot of our work having a positive impact, that whether it's providing specific red lines or we're providing guidance and we say, "Hey, here's ideal, but given the locale we're in, we'll dial that to a particular level."

I think there's a lot of stuff where we can help that interface between all parties involved. Development and commerce are very important, and trees are an asset in that. I think sometimes we get into a position where they're thought as barriers. It all contributes to a more livable community and more economic prosperity for people in our locations.

Doug: Before I let you go, no more science, no more urban tree talk, I want to know from you, tell me one of your favorite trees. [chuckles]

Sam: It's funny. It's going to sound stereotypical, but I really like aspens. If anyone from our local residential commercial offices here in Colorado are listening, I'm sorry for saying that. I know we have tough time at base camp, as it were here, but there is something about going up in the mountains here. That favorite tree predates my time here in Colorado. We've lived here a couple of years now. It's always just been one of my favorites. The fall color, the quaking of the leaves in the wind and things like that, I really can't beat it. Proud to say that quaking aspen, favorite tree.

Doug: Well, Sam, this has really been fascinating, very interesting, and fun. I want to thank you for your time. You and I are going to do a deep dive on this again. I really appreciate the information. I think we can even go deeper. We'll talk again.

Sam: Sounds great.

Doug: Thank you so much.

Sam: Thank you. Appreciate it.

Doug: What did you think? Do you like hearing questions from other listeners? Let us know. There's a couple different ways to reach us. You can send us an email to podcasts@davey.com. That's P-O-D-C-A-S-T-S @ D-A-V-E-Y.com. You can also click the link at the end of our show notes to text us a fan mail message. Your ideas or comments might be on a future podcast. We'd love to hear from you. Now, tune in every Thursday to the Talking Trees podcast. From the Davey Tree Expert Company, I'm your host, Doug Oster. As always, I want you to subscribe to the podcast so you'll never miss a show. As always, we like to remind you on the Talking Trees podcast, "Trees are the answer."

[00:26:10] [END OF AUDIO]