A simple experiment to see how trees are affected by growing in an urban environment has had surprising results, showing that they can grow up to eight times faster due to the urban heat island effect. For the Cornell University study, researchers planted red oak trees in New York City’s Central Park and places further upstate to measure the urban influence on the biology of the trees. Their dramatic results were not just in the overall growth, but the amount of foliage and carbon and nitrogen capture, as well.
New York has a bump in average maximum temperatures of 2.6 Celsius, and at night, the city is a full 4.6 C warmer than the nearby Catskill Mountains. The effect is called the urban heat island for the capacity of buildings and pavement to absorb solar radiation and hold it much more efficently than a vegetated landscape. The research follows a 2003 study in Nature which observed accelerated growth of poplar trees, but added better controls to account for other aspects of the urban environment like atmosphere composition where they grew trees in a lab. The results are that the red oaks in Central Park accumulated eight times the bio-mass in the same period as those grown in rural environments, and the further away from the city the slower the trees grew. We can only imagine what Terreform One will want to build now with this information.
The urban trees also have ten times the foliage and a much shallower root system. Nitrogen concentration in the city trees was 25 percent higher than the rural ones, and the city trees captured three times the amount of carbon. Basically the urban trees’ respiratory system is much more active in the warmer environment with the very positive effect of absorbing pollutants. How this translates to global warming is a whole different issue, but the study is very promising in the value of creating urban forests. Basically you get a lot more bang for your buck planting a tree in the city than in the country — more captured carbon and pollutants and a much larger tree to sit underneath to contemplate what they really meant by “the big apple.”
Via New York Times
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