The lush, dense, quality of rainforests instantly make one think of how beautiful and efficient they are at making fresh air (and thus suck up carbon). As a result of the obvious wonderfulness of rainforests we’ve done a lot of work to try to protect rainforests from destruction. We need to the same in our cities. In London, researchers used LIDAR technology to better understand how much carbon urban trees soak up. Trees in urban centres love to absorb that carbon! The proximity to carbon sources like automobiles make urban trees really effective at air-cleaning so much that they are comparable to rainforests.
Thank your local tree for making your air cleaner!
The UCL team used publicly available airborne lidar data collected by the UK Environment Agency, in conjunction with their ground measurements, to estimate biomass of all the 85,000 trees across Camden. These lidar measurements help to quantify the differences between urban and non-urban trees, allowing scientists to come up with a formula predicting the difference in size-to-mass ratio, and thus measuring the mass of urban trees more accurately.
The findings show that Camden has a median carbon density of around 50 tonnes of carbon per hectare (t/ha), rising to 380 t/ha in spots such as Hampstead Heath and Highgate Cemetery – that’s equivalent to values seen in temperate and tropical rainforests. Camden also has a high carbon density, compared to other cities in Europe and elsewhere. For example, Barcelona and Berlin have mean carbon densities of 7.3 and 11.2 t/ha respectively; major cities in the US have values of 7.7 t/ha and in China the equivalent figure is 21.3 t/ha.
Treepedia is a new tool from MIT that uses Google street view to evaluate what the coverage of trees are in specific areas. It lets you know what your neighbourhood is like and doesn’t just bias cities with big inaccessible parks. This means that cities (and people!) can use this tool to find where trees are most badly needed from the perspective of a pedestrian. Trees are more than just pollution-fighters, they make cities prettier and friendlier.
“Street greenery is a really important part of the urban environment,” says Xiaojiang Li, a postdoctoral fellow at MIT who helped develop Treepedia’s Green View Index, a measure of the tree coverage in a city overall and in any area within the city that a user wants to examine.
Trees provide shade for pedestrians in the summer and help to lower urban temperatures, Mr. Li says. They also help prevent water runoff during heavy rain and clean the air.
The MIT team used the Google photos instead of satellite imagery to “really measure how much greenery people might see” as they move around a city’s streets, Mr. Li says. Treepedia’s Green View Index doesn’t take city parks into account for that same reason.
Cleaning the air and keeping areas cool are what trees do best. A new study has looked into how best to use trees from a purely utilitarian standpoint. Essentially they drilled down to what trees do best and where they can thrive. The researchers cataloged the best places to plant trees based on factors like removing particulate matter from the air and where they can have the greatest impact on local temperatures. As a result their research outlines the most efficient use of money when deciding where to plant more trees.
As always, the best time to plant a tree is today.
There is one catch, though: The tree-planting campaign has to be well-targeted. And that gets a bit complex.
Trees only improve air quality in their immediate vicinity, about 100 feet or so. That means cities need to figure out which neighborhoods benefit most from new trees (typically the densest areas, but also areas around hospitals and schools). They also have to plant species that are most effective at trapping pollution (typically those with large leaves).
Officials also need to account for things like wind patterns and tree spacing and figure out whether they’ll be able to maintain their trees. Plus, if water is scarce, they’ll want to consider drought-tolerant varieties. And they may want to steer clear of trees that increase pollen and allergies.
TreeCanada has planted around 80 million trees! They do this because trees make the world a better, healthier place for everybody. They also plant trees to rejuvenate school yards (ones that got paved over at some point) and to bring back areas damaged by industrial uses to their . This past month they launched an interactive map of their plantings.
The map displays a satellite image of Canada with interactive buttons that allow you to explore its tree planting initiatives. By clicking on an icon, visitors can learn about the location and number of trees planted, as well as the program and sponsor associated with that project. Below the map, further details are available, including the species of the trees planted and the environmental benefit expected. The map is currently populated with trees planted in 2013, however, over time the map will grow to include planting sites from past and present years.
“At Tree Canada, we believe that investing in trees will benefit both human and environmental health,” Mr. Rosen said. “Trees help communities by providing shade, absorbing excess water, producing oxygen and providing habitat for wildlife. As our many sponsors can attest to, when you invest in trees, you invest in a legacy that will benefit communities for decades to come.”
One of Canada’s largest banks has announced that their economic research has concluded that in Toronto alone the tree canopy is worth $7 Billion (CAD). The non-monetary value of trees is obvious to most people and usually that’s enough to justify keeping trees around. However, there are people who only think in monetary terms and to those people we can now use the results of economic research to prove the greatness of trees.
If Toronto’s trees are worth $7 Billion, just imagine what the total value of trees are around the world!
It’s also well known that trees help manage temperature, both by blocking cold winds in winter, but also keeping the city cool in summer. Alexander said the net cooling effect on the city of a young, healthy tree is equivalent to 10 room-sized air conditioners, running 20 hours a day.
“On their own, these effects might seem small, but over the long term, these benefits make a significant contribution to environmental well-being,” Alexander said.
Beyond mitigating the need to belch out any more air pollution to cool the city, trees also provide an important role in storing pollutants already out there. The total amount of carbon currently stored in Toronto’s urban forest is estimated at 1.1 million tonnes — roughly the amount emitted by 700,000 cars a year.