Urban forests and their ecosystem services | Dr David Nowak (2015)

Urban forests and their ecosystem services | Dr David Nowak (2015)

well it's great to be around good morning it's actually a very good discussion I was interested and hopefully I can tie this all together and move forward because what we do is a lot people alluded to i-tree we build computer simulation systems to understand what urban forests do but the question is I think we want to wrap this up is is not what is where do you want to be you envisioned Dublin or wherever you are 50 years from now the question is how are you going to get there you are where you are you can look back at the past is there anything to see the past in this and Kristy alluded to engineering the question is what I want to go through today is and speakers before us to talked about this about the environmental services how do the trees provide that you can use green at the structure urban force whatever you want to call it to re-engineer cities the question is if you understand what they do you can do a better job and how they do it but also the questions before that is step one and Gerald you're getting to this is what do you have you have to have a starting point to say here's what we have today here's what it does if that discussion going the collaboration of understanding what the resources and then begin the discussions about where do you want to be in the future by understanding how the system works so what you have on this the street color maps can be very important so everybody said this from the beginning – so on the same page – from the perspective that we take the urban forest is everything all the green in the structure all the trees within the city it's not just one component we want to look at the whole city system from the public trees to the private trees and look at everything together this is from tinny gaming these numbers for the Greater Dublin area using i-tree canopy I think you did like 1,500 points you have about 19% tree covering the Greater Dublin you said about 10% with in Dublin itself that's your starting point you have a certain amount of thing said about 38% impervious cover then you have grass space that's that's your structure today the question is how are you going to change that and redesign it if you want to improve that by understanding what you have in into the future so that's your starting point so it's a management journey your starting point is what you have today and you want to envision where you want to be into the future that's what whole we can guide this than this process to to get this discussion going the key here is structure is critical and that's what we just talked about jail do you have that map of tree cover which locates the trees that I tree canopy only says the total amount it doesn't say where it is you're putting the trees where they are structure is what you have how many trees how many what are the species what's the health of the trees where they located those are the physical elements of the environment you have to start with that and you're already getting to that those that structure provides various services and a lot of the speakers before me have talked about these various service and I'll talk a little bit more in depth about them and that service has value to society so if you want to optimize value for the future society if the step back and say how am I going to change the structure that's what this is all about and get that dialogue in a collaboration going to how are we going to change the way we do business today to change the structure for a better tomorrow which will then enhance values and increase health for everybody it's all about leaf area it's not about the number of trees and your data show this of London Planetree the reason blown and plain Teresa quite has the most carbon and as does the greatest on the service is that the biggest ones out there and they have to be healthy trees dead trees have no leaves the question is how you distribute this leaf area because that's the functional part of the tree that does most of the services big trees do a lot more than small trees because they have a lot more leaves and they produce a lot more services tied to that you also have water you have to have water for these trees at the walk that the trees shut down into a drought period you lose the capacity of that gas exchange so it's all about engineering elements these are biological elements that change the environment because they're doing certain services to that and to basically understand the physics of this you're going to change the environment with that I'm going to give you my top ten Kristi talk about various ones Johan talked about various ponds I'm gonna go through my top ten and services of why we should have trees in cities in terms of the improving human health and environmental quality in cities so I ask you to think about what your top ten are cuz sometimes you come up with better ones than I do and these are mine in sequence number ten oxygen production every schoolchild knows that they're taught the trees produce oxygen I put this one on here because I throws out there's head absolutely no value driven Society and it's counterintuitive we all have to breathe trees produce a lot of oxygen for every basically the gas exchange but trees take in carbon through carbon dioxide they give off oxygen so a growing tree sequester's carbon gives off oxygen a decaying tree consumes oxygen and gives off carbon dioxide through decomposition it's in that balanced system but a healthy forest it's growing sprucing a lot of oxygen why don't trees there why don't trees have any value that they produced enough oxygen offset I think we've calculated the United States Officer the oxygen consumption of two-thirds of the US population the trees and cities crusing millions of tons of oxygen it's worth noting you have to put in perspective where you're at so we have about 67 million tons of oxygen being produced the answer lies to to various factors most of the atmosphere is oxygen around 21% is oxygen lack of production of more oxygen into this means nothing where no one's going to suffocate if all the plants in the world die we'll have other problems but we're not going to die suffocation is not the immediate problem also 90 over 90% of the world's oxygen production comes from oceans so I think what we need to do I pack throw this one out here it's might number 10 once we either shift the argument to where trees really have the impact where it's really important for human health oxygen production is not important for human health but there aren't many attributes in yohan mentioned a few of them that affect human health we need to get on to those affecting oxygen in the atmosphere is not the importance affecting a sliver there which is the trace gases carbon dioxide particulate matter things like that ozone is word trees don't have a very big important because they're gonna have a very small marginal change in a small fraction as a big impact on human health a small change and the big factor doesn't do that much number nine products and jobs this has to do with a couple things fruit and nut production if you want to feed we were asked to do when we asked to do eye tree to the food natural but Food and Agriculture Organization of the UN they didn't they were worried about third world countries and said they don't care about pollution removal they don't care about human health it well directly about that they want to know about food people have to eat they wanted a how much foods being produced from the forest not how much gas is being removed by the force so it's all in your perspective of worry about food production as part of this process but also at the end when the forest is removed we have a lot of biomass what do you do with the trees trees are not there forever they grow and they die and at the end at the end of the lifespan what do you do with all that biomass often what we do the United States which it's a waste wood product how do you get rid of it we chip it up and give it by the side of the roadside in other ways I mean it cost money to manage the air force why not return that like we do in forest production reproduce timber there's a lot of biomass we estimate we have 1.3 billion tons of dry weight biomass in our country which it produces about 26 million tons of waste each year which then is a cost to get rid of why not convert that into a benefit stream back to the city and either sell it back use it for ethanol food fuel production pallets wood pellets use it as a lot of our problems we burn fossil fuels why not reburn that wood back into the system reducing our energy consumption because Gerald's told that's live how much co2 comes out of cities that have using fossil fuels use some natural regeneration so we need to think about the whole city system of the forestry trees coming in and trees going out just potentially a lot of wood it's potentially out of nutrients so what do we do when the trees drop their leaves well we do in the United States we rake them up put them put them in bags whatever and get rid of off the site now what are we do in the springtime they call Chemlawn to come in and fertilize because we've don't have any nutrients those tons of nutrients in the leaves themselves they're just being pushed off site so then when you have man-made chemicals to bring it back into renew tract with more nutrients back to the site so we need to think about the cycle of this there's time involved with this trees grow and die and all these chemicals and mass are being moved around maybe we can do this more efficiently and not have to spend so much and get more money back into the system number eight noise reduction do Teresa actually reduce noise make the soil is actually better at doing noise to get the soil down into the Duff layer that mulch on the ground good at reducing trees more mask noise deflect noise and and and visually change noise so noise is often psychological if I do not see the source of the noise I perceive less sound even though I'm here in the same amount of sign if I put a visual blockage between me and the roadway psychologically it sounds quieter to me because I don't see the road so trees but by masking the roadways has a psychological change too they tend to deflect noises they can absorb some of they kind of deflect it so it changes direction they also mask noise because there's a psychology behind sound wind rustling through trees is a pleasant sound that people hear so they like that birds chirping in the trees there's a psychology of this sound so noise is important because cities tend to be noise we generate a lot of sounds through various attributes but thinking about how we designed to visually block silent sound or how we can mask sounds become important one of the most interesting things to me is after I think Hurricane Hugo went through or I think it was North Carolina I asked us asked someone after Dex they lost a lot of force to standard said what was the most important thing that changed in your environment and they said sound which I didn't expect that at all I expect it to be some visual thing and I said no there's sounds that I heard that I've never heard before freeways there were miles and miles away of traffic that I'd never heard before that was buffered by the forest that existed it was lost in that period so the change of it and the acoustic environment is very important in terms of trees we do not know the value of what that is it's very tough to model that that there is a whole psychology behind us but if you understand that but by understanding how sound works and how people's brains perceive sound you can make better designs number seven wildlife habitat this is one I think is one of the most tangible benefits that people can see they like wildlife they associated with wildlife we don't know the value there's a huge industry of about feeding wildlife I feed birds in my backyard people like to enhance wildlife habitat and there's much to this we're starting to do more into this but it's very locally specific because it has to do with force and the local wildlife habitats that you have again we don't know the value to this number six this will get more into the these last six or more to engineering and changing the environment reductions in UV radiation we're talking here about is increases with a thinning of the high level ozone layer due to cook floor o´clock chlorofluorocarbons that thinning of the ozone layer so particularly in Australia and southern hemispheres in springtime that whole opens up you get more of this shortwave radiation coming in leaves the skin cancer cataracts that's why you have the Sun protectant factors you might have a big as much of a problem here in Ireland but in southern United States we have to put the suntan lotion on to protect from skin cancer things like this but trees do the same things they act like a sun protection factor tree leaves absorb 95% of ultraviolet radiation all right so if you're standing and this has to do again design if you're trying to protect certain populations that are exposed to sunlight particularly where we think about is designing school yards where children might be out playing is try to shade them another question my answer is one yes but our city don't give the answer if you were in my lecture yesterday but if you're standing think about this if you take a lawn chair and you're in the middle of a field and you sit in the shadow of a tree on a sunny day and truly absorb 95% of ultraviolet radiation what percent radiation reduction do you think you're getting by sitting in the shadow of that tree any guesses on that it's actually only about 50% so the question is why this is understanding again the physics of the system and if you're going to design why if trees are absorbing 96 per 95 percent of ultraviolet radiation if I'm sitting in the shadow of a tree on a sunny day am I not getting a hundred percent reduction in UV radiation you have to do with what you're seeing here the blue sky you'll be reflecting off of various particles in the atmosphere so it's not all coming from the direct beam of the Sun it's coming from blue sky so you want to design if you're protecting for human health you want to design not only blocking the Sun but blocking the sky because half of it's coming from the sky view this gets it's again about designing elements and the reason I tell you this if you understand how it works and you take the maps that you're producing and looking at the human populations of who's being exposed you might design differently in a schoolyard then you would along the right Parian zone or maybe certain area so how you design this for understanding what the forest is doing this is the blocking of light but not other blocking the Sun but also having to block the sky view so get that back scattering we do not know the value of that actually we're building out a UV radiation program right now and I agree to look at this and try to look at exposure to human populations relative to tree canopy number five greenhouse gas production it has to do with climate change the gerald chosen owners on this from dublin pretty much the the general rule here is this is one of the easiest services to to measure from a forest in terms of sequestration is that half of the dry weight of a tree comes from carbon from the atmosphere so if you would see a tree getting bigger it is taking carbon out of the atmosphere because it's converted to carbon dioxide in the atmosphere into the biomass of that tree all the other ones some of these elements are very difficult to model or to understand this one i can directly measure it's right there I can see it the trees gotten bigger I've sequestered carbon and you could show you so that with the London plain tree now the problem with this as compared to other services yes oh I forgot your numbers for what you had for Dublin but I mean our numbers are we're talking millions of tons of wood stored and as the trees grow each year they sequester more carbon they take in the carbon dioxide give off oxygen and store that carbon of the wood so as the trees get bigger they're taking out more carbon on an annual basis which is your you were showing that summertime effect from the flux towers is trees are taking in their car during summertime which is offsetting some of the auto emissions the question on this if you think about this from a times perspective though city of Dublin you have all this carbon stored in the city what happens when that tree dies where does the carbon go I was alluding to that partly with the products so what do we do at least in our country what do we do we take that tree down now it's it's it's removed from the system we run it through the chip or chip it all up now what are we doing accelerating the release of the carbon that this tree took 50 to 100 years to store and or we burn it which is okay if we burn it for fuel because then we're offsetting fossil fuel use but if we just burn it all the carbon that this tree is taken out of the atmosphere most of the carbon that this tree is taken out of the atmosphere over the last 50 hundred years is given back to the out to the atmosphere so how do you solve that trees are basically carbon cycle errs they take carbon and whether the same way our body systems propose their carbon when we die the carbon goes back trees are doing the same thing so how do you how can you solve that one is you can see here on this room you can store some of it in wood products which then will still delay the removal of the carbon back the atmosphere the other option which we'll talk about little bit laters take the carbon and burn for energy use if you update the carbon you lose that carbon eventually utilize that carbon as a resource to offset the problem which is the carbon emissions in the first place coming from the burning of oil and things like this again the point of this is we need to think larger scale and more systematically it's not all about trees just storing carbon it's about the time series of what happened from the past carbon what's going to happen to the future carbon number four water quality improvement news includes also flooding within that and people have talked about this the basic process here is probably to fold in some ways you have leaves out there when it rains the leaves go on to the water for a little bit and then the water runs off and it goes into the soils for the most part under heavy rain events trees have very relatively small impact you take a fire hose to a tree and run the water on it most that water's going to blow right through that canopy but in the light rain events trees have a significant impact and most great events are light rain events they intercept that water and prevent the water from going into the soil system to is in the heavy rain events the trees slow down the rate which the water is hitting the ground therefore allowing the soils beneath the tree to in fulfilling the water to infiltrate into the soils so the problem that we have with flooding and the problem we have with water quality is the water is not getting into the soils it's creating runoff on the surfaces and taking the pollutants that are on the surfaces and running them to the stream so we had two problems in urban areas one is we put the impervious surfaces down which we have to have buildings and roads which do not allow water to infiltrate into the soils trees are not really going to solve that problem because we're gonna need that infrastructure if you plant trees over impervious surfaces though you can help reduce some of that runoff or allow more time for city let's say street sweepers to come in and clean that surface before that those pollutants will wash off into this into these stream systems impervious surfaces are the main culprit behind the water issue so that we have in cities trees will help a little bit but if I had one choice of what to pick if I could take up 1% and break up 1% of impervious cover or plant 1% additional tree cover I would break up the impervious surfaces if it is no brainer trees will have an impact but the relative difference between impervious surfaces versus trees on water is about a 10 to 12 to 1 ratio which means for every 1% impervious cover that you add to an area you'd have to add about 10 to 12 percent canopy cover to offset the impact of that 1% impervious because the impervious what's happening if you seal that soil you're not allowing that water to get into the soil so where does it have to go we usually pipe it to get it off the system so then it flushes it into the stream rather rapidly the problem with water quality and water flow issues is trying it we're not getting enough water into the soil system we're gonna have more and more issues with climate change going on where the rain intensities are going to change where we we're seeing this in the States already the we're getting more precipitation but it's not so much the total it's the duration when it comes in it's more of these heavy rain events my house flooded for the first time ever like three years ago just because we had such an intense rain I'm on top of a hill and I had water running into my basement door because it couldn't saturated soil couldn't take it up fast enough so you want to get that water into the soils and the more we put in pervious surfaces down but less we're getting the water into the soils and the mold of pushing it to the streams at a faster rate so trees do have an impact they also take up nutrients and they also dry out the soil so when they're evaporating water it creates it removes the water from the soil into the atmosphere which creates more airspace for the next rain event the soils are not saturated as much to allow that water to percolate in so that you think about it trees are just basically pumps of water they take in carbon give off oxygen and they pump out water constantly and are drawing out the soils which is important attribute when we get to some of the other benefits and this is one of them here air quality improvement again it's all about the leaves you have two attributes that are going on when the stoll mates on the leaves the little holes in the bottom leaves open up to allow water to evaporate out at the same time if you think about it if you take it then the stoma mates open there's more pollution outside the leaf than inside the leaf and inside the leaf there's a lot of water so basically you're creating a concentration gradient you may have ozone at high concentration outside the leaf it diffuses inside the leaf and then has taken up inside the leaf services so we have these basically filters millions of leaves out there that are constantly exchanging gases as they're that's why you need water to get that keep the snow mates open the pollutants are moving the gaseous pollutants are moving into the leaves and are being removed for the most part they are not harmful actually sulfur and nitrogen can act as a fertilizer sulfur dioxide and nitrogen dioxide actually help the trees grow ozone will damage the leaf carbon monoxides not taken up that much so we have a constant source of pollution be removed if you think about it during the daytime when it's not raining in the rain removing it who else who what else is taking up air pollution besides the trees it's you and me we're gonna need to breathe it in or they're gonna breathe in it the more they're breathing it in the less you're gonna be breathing in it for particles it's a little bit different with fine particulate matter PM 2.5 took a matter less than 2.5 microns or the small dust those are the ones that stay retained in the atmosphere a long period of time they don't settle out very well and they go deep into our lung system this is really tiny particles they can't be captured on the surfaces of the leaves so conifers are very good because they offer year-round protection or evergreen trees offer year round protection surface textures such as hairy leaves sticky leaves the more the particles get and stick to the surface the better off you're going to have does the particle stay on the surface forever the answer's no the ultimate resting place for particles is going to be the soil two ways leaves drop during this in the fall in the winter time any particles are on the leaves then move to the soil but more importantly when it rains the rain washes the particles off the leaves and moves them to the soil most of the particles are water soluble and they dissolve some are not and these are the ones of the problems heavy metals pieces of lead cadmium zinc do not dissolve in water and some poly aromatic hydrocarbon are not dissolved and they move to the soil system so what's happening there this is a little bit different than gases is particles if they don't dissolve are not being removed from the system trees are removing them from the air and transferring them to the soil and if you think about it environmentally done you've got another issue and this is happening in cities in Europe it's already being shown in the United States around the base of trees we're getting high concentrations of these pollutants that the trees are taking out because they're very effective or removing the air or the particles from the air and then dropping into the soil so now you've got a soil problem the particles knock on a piece of lead is not removed from the system it's just transferred from the air to the soil so now if you're going to do urban agriculture or try to go probably things with the soils you have to consider that the pollutants in those chits change position for some of the particles but they are fairly effective at removing pollution trees they're over dogs in English 30 76 centimeters in diameter versus less than trees less than 7 centimeters in diameter remove about 70 times more pollution than large tree moves about 70 times more pollution in a small tree because the leaf area is 70 times greater more capacity to capture the particles more capacity to capture the gases those big trees are a lot less of you're seeing right there for the London plane trees do a lot more than small trees we have to make me us 7 100,000 tons of pollution air moving in but in basically we've been done if you if you remove pollution from the atmosphere you have a certain boundary layer height from the atmosphere which then changes the concentration if treat the tree removal reduces the concentration of the pollution in the atmosphere it affects human health particularly for a particulate matter and ozone did improves reduces the number of deaths cases of asthma respiratory symptoms the ideas we're living in this space what we have to breathe the more we can clean the air the better off we'd have in terms of relating to human health you own already mention this to that one slightly need to consider there are times when the trees might actually increase concentrations in this case it could create a tunneling effect the pollution is trapped more within this it's not allowing a pollutions to disperse it's trapped in that area so if you're walking along that roadside even though the force is reducing pollution overall at local spots it might be increasing the concentrations this is the question if you want to make many make bicycle trails and keep the cars off this would be a great site to walk through and live there weren't the cars the problem is the emission source is right at the same spot where you breathe those automobile tailpipes and we have to understand where it's coming from and who's breathing that pollutant in number to socio-economic and aesthetics people like trees a lot of people a little bit earlier question of tourism stimulating business people will will stay around areas longer and shop more in areas that are more aesthetically pleasing if they like the environment people's patterns of cortisol and stress reductions our bodies we react to seeing vegetation this is huge and as Yolanda was saying there's a lot more research going into this about bodies react our people's reactions to seeing the vegetation but it also has to do with design of Commerce in many ways if you make environments if you want to bring jobs in or tourism in or people to shop making the environment more aesthetically pleasing will bring the people and they'll stay longer number one and again is is from Anna probably in American perspectives and I said this yesterday people audience said well we don't care about cooler our temperatures anywhere but temperature is key in city systems and the questions that you show this too on heat islands when you warm the environment which we do because we burn fossil fuels because we put in pervious surfaces down this has a huge impact on energy use and on human health and the more we can cool the environment down the better off we will be we did a model run with the US EPA and art from our side trying to look at the effects of trees on air quality but to looked at pollution removal and everything else and we also had to tie into this air temperatures because if I reduced temperatures I reduce the emissions from cities and the one thing our the EPA then you care about pollution removal the most I mean they did a little bit the one thing the engineers really stuck to was the temperature reduction by changing temperatures of cities from one to two degrees had huge implications for ozone production and emissions of pollutions they said of anything they wanted to do a fake-out is the one to one degree temperature reduction in cities that's a massive change in air quality because it affects so many other things that are associated with temperatures even the trees are associated as temperatures change the trees react differently so this graphic shows basically as temperature goes up we tend to have more ozone being produced because the more emissions the photochemistry changes the boundary layer conditions change so it ties back into that again power demand is associated with temperatures particularly in our country as pollute as temperatures go up we tend to burn more fuels to reduce energy so in addition to temperature reductions we also have energy conservation and this goes both ways both winter and summer time and you have to be careful particularly here in Ireland probably saying with the United States is and again you had the slide of shade if shade going on which if you shade a building in the summertime it's a good thing it cools the building dock if you shade a building in the wintertime heating costs go up so yes be careful on shade you have the temperature effect which is predominantly a summertime effect which is good but then you also have blocking of winter winds again you were talking about the one who's talking about the the more the wind speeds generate through the city the more we have to heat our buildings because the air infiltrating into the building so how do we design cities with vegetation in the wintertime to block the winds and summertime to shade the buildings but you have to be careful in the wintertime not to shade the buildings this is important people think when it's came up yesterday's that trees out of leaf it won't be an issue but it is somewhat of an issue trees and leaf the deciduous tree and leaf will block anywhere between seventy to ninety percent of the light going through which is great in the summertime so then in the wintertime it drops their leaves that tree is still probably blocking between thirty to forty percent of that radiation hitting that building so a tree out of leaf on the south side your buildings actually increasing your energy is even though you're seeing more of the sky view it's blocking a lot of that radiation that would have hit the building to warm it up so we have to be careful about designs in the wintertime again if we reduce energy you so we design smartly where we place our trees we reduce energy use to reduce the emissions from power plants then affect air quality so it ripples back in it's all a system approach we estimate seven two point eight billion dollar saved in our country but in addition that another 2.2 billion of health effects because if I reduce energy use I don't emit co2 I don't even particles from the power plants it all ties back into that to their secondary effects and these are the emissions that are going from our country so particulate matter methane nitrogen oxides sulfur VOCs they're all given off by our power plants which then feeds back into human health these are numbers from our country the bottom line which is probably comparable to you have over here you're talking about $1,900 per hectare of tree cover just for those few things that we can look at is energy is pollution removal carbon and avoided emissions but if you look at it I had 10 on my list Johan and Christie showed many others regulatory services and others that aren't even on this lesson we're already stuck we're starting at a base point of $1,900 per hectare of tree cover per year of services being provided by the forest which is going to go higher if we could quantify UV radiation if we could quantify the water better if we had quantify the aesthetics which we can't put values on them yet so that's your base point of what the value of that force is coming back so just lastly to talk briefly about high tree and then I'll finish that that's it for me but I appreciate being here having discussions last few days I tree is a free public domain tool we're releasing a version for the UK November we are working on a European version but it's going to take it's at least a year or two it has to do with data differences the model will function here in Ireland the problem is your data systems and we look to your pollution data it's not formatted the same as ours so that the reformat the data to load it into the system but the concept behind this is basically I talked about earlier structure function value the hope is people in Dublin or Island or wherever you're going to be will measure something about a tree with those measurements into the system and we can quantify back the ecosystem services provided by the trees and provide the values it has been used worldwide over 60,000 users in various countries it's just more difficult to work outside now the United Kingdom Canada the United States or Australia where we have versions that automatically work there are suite of tools some of them to look at – you can assess canopy cover you can assess your trees Street trees any area if you just measure trees can go into this we have a hydrologic model that can look at water flows encourage you to look at the website site tree tools org and you can try the tools out these are the benefits on the top of the ones that we're already quantifying the ones in the green down to the bottom like such as cooler air temperatures UV radiation wildlife and things like that we're already working on now they're just not out yet this models been in development for over 20 years and it's going to keep the in development we have a new forecast model to it which we think is real cool is coming out in November if you have data for Dublin so say tinnies 10,000 trees you can load them in there and then do projections forward of what the services will provide over a certain number of years you decide you can grow the trees and kill them off it's up to you but it'll show future events again there's tinny's numbers Guinness and Gerald haggis so you have about 10,000 trees just in that city centre you're talking about that provide services to people that's six percent tree cover so this is a series of tools if you want to look at what the forest is worth you can use those tools how much canopy cover you can use canopy trees to plant to remove what we're trying to do the concept behind this model in the original development is if I can only if I could ask answer try and answer one question if I could only plant one tree in the city in Dublin what would I plant and where would I plant it and now also when what I plant it if you take in a time series and that's what we're trying to answer and that question becomes in the context of what do you care about in Dublin so what the plant and where to plant it depends on what problems you have and where you exist so if I'm worried about air quality I might plant over here and do this species don't worry about water it might be over here so the models trying to be open-source spaces that allow you to make do we don't know what your problem is in Dublin or in London or anywhere we know the problems are universally consistent it just might vary at different levels so the answer the question Pollan will ask you what let's look at your data here's what you have here's where you're going to be what do you want to have and they're trying to build an optimization routine that says I've given the data you have and given that you really are concerned about air quality of water we will recommend species it will recommend locations and then we're going to be recommending when to plant and that's the idea of trying to future out you have what you have today get the discussions going about where do you want to be 30 50 years from now and start making the smart decisions and climate change is going to mess this up in some ways this trees your planting today might not be the same trees you're gonna be planting 50 years from now if the climates are going to change so it's a system that's evolving so we need to keep up and you need to keep maintaining datasets so I I think you're doing a great job as you do the tree cover mapping which dining to collect data on the trees this gives you the discussion point where you can have more intelligent discussions about the future so that's all I have but I encourage you to facilitate this

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4 thoughts on “Urban forests and their ecosystem services | Dr David Nowak (2015)

  1. Yes, if you cut down all the trees, in four years there will still be same amount of Oxygen! Because of Emerald Ash Borer…here in Cook county Chicago, we just lost 13 million trees that produced most cover of green, to borers within a biblical six years. I have documented this urban forest disaster. Learn more about Ash tree/EAB event by checking out my Scottie Ash Seed blog

  2. if you're concerned about "pollution " I hope you're interested in seeing an end to the weather modification which criss crosses our skies into grids all around the world. Dumping millions of nano particles utility foglets on the soil in every living thing.
    But it works out so well for UN's Agenda, Sustainable Development, it helps to pull the wool over the sheep's eyes with Mr. UN Maurice Strong giving "climate change" a real foot to stand on, such is the scam and isn't it a perfect little scam for the one world government at that, dementia and Alzheimer's slow kill is a lucrative kill..

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