Kenton Rogers

Thanks to KaarbonTech for having us. My job this morning is to set the scene around tree benefits on the highway. For those of you who don't know me, I co-founded Treeconomics, a social enterprise business based in Exeter with around eight of us there. A lot of the work we do is with those managing trees, looking at tree benefits and helping to enable sustainable tree escapes. We've been going for around 10 years. At that time, we did the pilot project in Torbay, which was the first time in the UK that trees were looked at not just as liabilities. Quite often trees are managed in the context of hazard and risk, which is important, but what's missing is the benefit side of the equation. This was the first time a whole urban forest was looked at as assets rather than liabilities. Since then, in 2010, we worked on around 30 city projects, most of which have been collaborative. We've done a lot of work with some people in the room, especially Kieran at Forest Research, which we'll mention later. We did a tree inventory in Hyde Park and other London parks. Recently, we worked with a tree nursery to get carbon performance certificates so that when you purchase a tree, you get one of these certificates, similar to what you find in a fridge or washing machine, to help inform choices around putting in trees that will last longer, store more carbon, and provide more benefits over time. The reason we're doing this is because urban forests are an overlooked and undervalued resource, at a time when we need them more because they make better places to live. Globally, over 50% of the population live in urban centres, expected to increase to 70% by 2050. In the UK, we're already at 90% living in denser urban environments. Because trees are overlooked and undervalued, we're losing them at an alarming rate. The USDA Forest Service estimates 36 million trees are lost every year in America due to development, vandalism, poor management, and old age. To put that into context, there are 8 million trees in London's urban forest. Added to that, 67% of urban forests in the UK have no proactive management. Many public trees aren't even inventoried. Trees provide benefits, and there's a common international classification for ecosystem services with around 100 benefits listed. Around 20 relate to urban trees and woodlands. Of those 20, we can quantify and gauge the effect of about 10, like how many grams of pollution they're filtering and how much they lower the urban heat effect. Of those, we can value about five. These 20 are listed here. If you scan the QR code, you can have a copy. Out of those 100, 20 are relevant to urban trees, like increasing restaurant patronage by 15% on weekends and 7% during the week, improving concentration in school children and office workers, reducing stress, and providing conductivity. Of those 20, we can value about five, and I'll concentrate on those that relate to highways, like restored water attenuation, pollution removal, and shading. Trees are very good at capturing particulates and pollution on their leaf surfaces and bark. Shrubs are also very good because they capture pollutants at low levels. Mixing trees with shrubs further increases that effect. Across London, we estimated 14% of road transport emissions can be filtered by the urban forest, a service worth around 150 million pounds every year. We can value that using the UK social damage costs. Here, we can see the pollution breakdown month by month and pollutant by pollutant, and also tree species by tree species. Cooling effects can be measured but not quite valued yet. There are examples from Pristina in Kosovo and Malmo in Sweden. Trees lower temperatures, improving thermal comfort and are important for pavements and roads. Roads soften with surface temperatures around 50°C. Even though we don't experience those summer temperatures in the UK, roads absorb a lot of heat, and when air temperatures are in the high twenties or 30 degrees, roads soften, causing pavement fatigue and heave and rotting. Trees can prolong the life of asphalt. This research has been done on that. You need tree canopies for that effect. Noise reduction is another benefit. Trees reduce noise. Older studies in the seventies used twigs and branches in a wind tunnel, but recent studies from 2014 show that a shelterbelt 15m wide can have a considerable effect, although 30m is optimal. You need to mix the trees up a bit for the most benefit. To manage and plan for trees, you need randomness of size and species for different textures to capture noise, and a build up of soil organic matter. You need the trees there to provide that effect. If the trees aren't growing, they won't provide any benefit. This is an example from my area, a wasted opportunity. The guard meant to protect the tree is now why it needs removing, as it's grown around it, compromising its structural integrity. Strimming rain trees is another issue. Overzealous mowing and strimming occurs across the UK. The cambium layer just under the bark is the life of the tree, where nutrients and water are transported. It's easy to avoid, but expensive. It's crazy that money is spent planting trees, and then someone is paid to kill them. In Torbay, trees are put in with three stakes and mulch, providing a visual and physical barrier to mowers and strimming, allowing the tree to thrive. In Peterborough, they put all the trees in before building infrastructure. They have a footpath, a row of trees, tall bog meadow grass, the road, a row of trees, a cycle path, a row of trees, another footpath, a row of trees, and a hedge. Planning like this can avoid future ghettos. It comes down to measuring the true benefits and ensuring that value can be put across in cost benefit analysis, and ensuring we get bigger canopy trees. Bigger canopies filter more pollution, hold more rainwater, store more carbon, and have a greater photosynthetic area. We did work with Green Blue Urban on this, looking at a concept model from Jeremy Barrel. If you're replacing trees every 20 years, you'll never realize any tree benefits. You're spending money to replace dead trees. Tree benefits really start increasing after 20 or 30 years. Jeremy Barrel's trees were London plane trees 200 years old, which is remarkable. The oldest London plane tree in the UK, planted in 1647, still has extension growth. If given space, it has a much bigger effect than we thought. I want to briefly touch on the work we do with i-Tree. I-Tree is a free, open-source, peer-reviewed model that provides information on tree benefits. In the US, it's had about $20 million of investment. In 2010, we tested it with Kieran and his team, who provided data into the model. It uses weather, meteorological, and geographical data combined with your inventory data or data that CarbonTech can collect. It provides information on tree benefits, like air quality, pollution removal, and carbon storage, and they're also doing work with human health and well-being. Data doesn't mean action. It needs interpreting. There are over 100 reports within i-Tree, looking at urban forest food, UV factors, and oxygen production. You don't want to see everything, so you need to provide useful results to manage your trees. Here's an example from our work with Highways England. You can look at air pollution removal and tree health. You can pick up patterns. Ash shows that many ash trees aren't healthy, and ash dieback is a recent issue. This data can be incorporated into management briefings. When you have information on all your trees, you can look at ash trees and how many will be lost. In this instance, it's around 14 million to replace all those ash trees. You need to replace them all because their soft estate is a collection of trees. This graph shows a projection of ash dieback effects within the i-Tree ECO model. You can add different diseases, storm events, and mortality rates, and planting. It shows a decline, but not as bad as expected. There's also information on the ecosystem services provided by those ash trees. I'll quickly show you the i-Tree design tool. This data can be used for planting and removing trees. Together with Highways England, we developed the design tool for their designers when planning a new slip road or roundabout. You'll be taking out trees and natural areas, like grass, soils, and hedges. You'll plant new trees, but will they replace the benefits? You can choose different tree species on the map, and on the left, it will tell you when the trees you've planted will replace the benefits. In some instances, you haven't planted enough trees, so you need to choose new species or increase the number. Here's another example of the tree tags we did. Even when ordering trees, you can make better decisions around which trees to put back, which ones will store more carbon, and provide growth above and below ground to provide adequate canopy cover. That's a quick overview of tree benefits and trees on the highways. Thank you for your time. I've put up information and research from this presentation. Thank you, and I look forward to the rest of the day. Thank you again for all of them