Greg McPherson, Center for Urban Forest Research
K So what I’ll ask you to do Greg is just to say your full name and your institutional affiliation to get us started and then we’ll just go ahead and jump right in.
G Alright. My name is Greg McPherson and I’m Director of the Center for Urban Forest Research, that’s affiliated with the USDA Forest Service Pacific Southwest Research Station. And we’re located in Davis, California.
K Okay. Thank you very much and again thank you for agreeing on rather short notice to take us on here. So the first question is sort of a warm up question. The question is, can you describe an incident in your life that first inspired you to become engaged in community greening and community forestry?
G Yeah I think, I grew up in a small town in Michigan in between Detroit and Lansing called Hollow Michigan, and when I was a little boy many of the streets in that community like throughout the Midwest were graced with some very beautiful American elm trees. And I remember you know playing under that arching kid and in the shade and protection from the elements and the beauty associated with those mature trees. And one day some people came by and they attached these vials with rubber tubes to the trees. And I realized that those trees were beginning to suffer, to die back and that they were trying to save those trees and improve their health. And after a while they actually went in and started cutting the roots, you know tunneling between the trees and it was all kind of for naught because one by one those large American elms died. And they came down and all of a sudden the street that I lived on was totally transformed into this very open space. And a treeless environment. And it just made it really struck me as a tremendous loss and I really didn’t like it in that exposed and open type of environment that created and even though some replacement trees were planted, it really totally changed my play environment. So that just you know at the time I didn’t really have any idea I’d be studying urban forestry and become a researcher but I think that I know that struck me in kind of very visceral way.
K And so perhaps then was inspiration at the outset.
G Yeah I think it might have been.
K How do you, a little follow on question with that. What was it that you thought you would miss when you saw that all happening? Besides seeing the canopy disappear and be replaced by whatever eight, ten foot saplings basically, how did it make you feel as a kid?
G Well you know we just really I mean Michigan does have a pretty you know warm and humid summer at least for a weeks in August. And it can get pretty hot. So we certainly, I enjoyed having the shade and having the protection and the kind of like the roof that that canopy provided really for the entire, not just the street but the front yards and so it was a kind of a filtered shade and you know clean air. And just kind of a protective type of feeling. A womb like feeling that those trees created. And although you know they weren’t trees that I could climb in, you know because they it’s so high up that they begin to branch, they just they had kind of an indescribable effect and their loss was noticed.
K Right. Okay then well our second question which is related. If you fast forward to today when you think about, if you think about this with most of the people that we’ve talked to say huh, I haven’t stopped to really think about that in a while. What motivates you to do community greening, urban forestry kinds of research now?
G Well I think I’m motivated by you know the desire to make a difference and you know I hope that the research that I’m doing can be used to create a greener, healthier environment for people. And you know what we do is quantified in the benefits of the costs of trees. We hope that that will stimulate investment in urban forests and their managements. And by attaching monetary value to all of the services that urban forests provide, we hope to increase appreciation of their value and greater investment in trees. And I guess I look around and you know I see the investment that’s been made in the infrastructure of our cities and our highways and streets and roads and our sewer system and our water systems and you know in our schools and our hospitals and healthcare, but I don’t see that same investment, that same concern about you know the natural environment, the green environment in our cities. And it’s, while we’ve done a lot to engineer our communities to facilitate us getting around in our vehicles, we haven’t really shown the same concern for creating an environment that puts us in contact with nature and that really maximizes all of the ecosystem services that trees and greenery can provide.
K Right. That’s great. Actually those are nice quotable nuggets. Thank you very much. And that actually leads us to our third question. Based on some of those ecological or environmental services and your role in research around that, what is your most important finding for greening advocates and for policy makers in a sense?
G Well I’d say the most important finding is that the benefits of trees in most cases far outweigh the costs. And we’ve studied the, probably 15 different cities around the country and actually and outside the United States as well from Lisbon, Portugal, New York City, San Francisco, to smaller cities like Fort Collins in Minneapolis, Charleston and Charlotte and Glendale, Arizona and Santa Monica, California. And we’ve found that when you add up all the benefits that trees provide, whether it be energy savings, air quality improvement, reduced storm water runoff, carbon sequestration, increased property values, improved aesthetics and then you subtract all of the costs associated with managing trees, not just planting and pruning and removing dead trees, but costs associated with say returning sidewalks that the roots of trees heave up and money spent on resolving trip and fall cases because these sidewalks you know cause people to hurt themselves. And money spent in cleaning up after storms where trees have fallen down and blocked streets. And all those other costs. The benefits will be two to three times greater than the costs. So I think the most important finding is that for every dollar spent on managing and caring for trees, residents of cities received two to three dollars or as much as four dollars back in return. So trees pay for themselves. They put money in our pocketbooks really. Because of all of the services that they provide. Although no one has paid a tree to provide these services, they are working 24 hours a day, seven days a week to protect us from the elements, to clean the air we breathe and clean our water, to nurture us psychologically, spiritually and improve our quality of life. And I think that sometimes we don’t value trees because we don’t pay for these services. But and as a result you know we undervalue these services. So I think our most important finding is that you can attach a value to these services and that in most cases trees pay for themselves.
K Okay. So then based on that answer, which I appreciate very much, how do you feel the results of that work and those findings can be used to advocate for community greening by those advocates I mentioned earlier or even you know friendly policy makers? How do we use those results to advocate?
G Well I think we use those results by, I think you know every community has urban forest resource. And so I think that the research and the tools we provided for example I Tree, which is an urban forest assessment and evaluation computer program, or suite of computer programs, can be used by any community, every community to fairly rapidly determine what the resource is, what the street and park tree resource is for example in their community. And the value of services that those trees are providing on an annual basis. And also what’s needed in terms of management for those trees. How many trees are dead and should be taken down? How many vacant planting sites are there that need trees? How many trees need to be pruned to improve their health or treated for pests or disease? So it provides us a way to kind of go out there and rapidly sample you know tree volunteers to identify trees and sample trees and then we can use that information in our community to identify what are the key things we need to focus on to improve the health of our community forests? What are the value of the services they provide? And how do we move forward to address the issues that are most relevant in our community? Whether it be a need for new planting, the need to protect and care for our old mature trees that may be reaching the end of their life span. The need to you know enhance and rehabilitate areas of the city that don’t have trees. So I think that we can use the research that we’ve developed to advocate for resources because we can show the value of trees and use those resources to better understand the trees in our community, what their needs are, what their value is and how we should act in our community to improve the health and to increase the canopy cover of our cities.
K And do you think the answer changes if I say thinking just about the policy community now, not about the advocates, how do the results of your research influence policy or how can they be used to influence policy? Just targeting those policy makers.
G Well I think that in the past trees have been viewed as kind of an amenity, as a luxury, as a nicety, as an attractive kind of part of the landscape. But their functional, functionality has never really been fully appreciated. And so now I think that air quality regulators, strong water management regulators, people involved in the issues of global climate change are beginning to see that the urban forest can play a role in improving our air, in improving the quality of our water, and improving the, and protecting our climate. And you know that’s really a result of us being able to quantify the benefits that trees provide in terms of ozone uptake and you know kilograms per tree per year. Or energy savings in terms of kilowatts of air conditioning that we don’t have to have. And then the pounds of carbon dioxide that are no longer emitted from you know coal burning power plant because we don’t need that air conditioning because we have a tree on the west side of our home that is cooling the structure. So I think yeah so does that…?
K Yeah that’s good for the policy makers especially. So the question then is, and this follows on nicely, we’re actually moving through these questions well. Given all of that background and the research that you’re doing and the implications of that research for advocacy or for policy makers, what in your opinion are the important questions in research approaches for future community greening, urban forestry research? Where should we be headed as a research community?
G Wow. Well that’s a tough one. There’s a lot we don’t know and certainly you know I think one of the things that we’re working on that we’re trying to do a better job of is using some of the new technologies in terms of remote sensing to determine you know what, how the canopy cover of communities has changed over time as communities grow outward and forests on the edges of our cities are subsumed in urban development, trees are lost but then development occurs new trees are planted in an urban forest. So we can look historically and see how canopy cover has changed. We can use these new high resolution satellite images to identify what the existing canopy cover is and what the potential for tree planting is throughout the community. And then predict you know what the future benefits will be of different levels of tree planting and different types of trees and different areas of the city. So I think that’s kind of an exciting area of investigation and then there’s the whole human dimension in terms of you know what are the obstacles to increasing canopy cover related to people’s attitudes and perceptions about trees. And what are the barriers to tree planting in terms of people’s willingness to plant and care for trees? What are the combinations of incentives that can be used to overcome some of those barriers? So how do we, how do we create a market for trees in our community and then what, you know then there’s a lot of issues in terms of you know what are the benefits of trees. Different types of situations where we have high levels of air pollution and you know what are the appropriate environments underground, the types of soils that, and engineered soils that are required to allow a tree to grow and thrive. But maybe also functioning to filter pollutant runoff and viaduct and how to fight over remediation in terms of cleaning the runoff and reducing the amount of runoff that goes into rivers and streams and oceans. So there’s kind of a lot of issues related to tree selection and you know engineering trees and soils in a way that will provide you know a variety of benefits while sustaining a healthy tree over a long period of time.
K I’m sure you’re familiar with Nina Basick, a colleague of ours.
G Yes, she’s done some great work in that area. Peter Trowbridge and her are certainly leaders in those areas.
K Well the, amazing time is flying by. We’re at the million dollar question, this is the last question.
G Okay.
K So I’ll give you the setup for the question. The United Nations identified through their own deliberation, four factors as indicators of sustainability in cities. And those factors were, one was just and peaceful, number two was resilient, number three was ecologically efficient, and number four was economically viable. You don’t have to remember all those. So the UN decided those are the indicators of sustainability in cities. Given that, in what ways do you feel that urban community greening, urban community forestry, contributes to the four criteria for sustainable cities or more broadly, to sustainable cities?