Urban Heat Effect Drives Faster Tree Growth, Study Says

In a new study, researchers say native red oak seedlings planted in New York City grew far faster than in cooler rural settings. After planting seedlings in two city locations, including Central Park, and in separate locations in the Hudson River Valley and the foothills of the Catskill Mountains, researchers from Columbia University’s Lamont-Doherty Earth Observatory found that the city trees produced eight times more biomass than those planted in the country. According to their study, published in the journal Tree Physiology, the city trees were exposed to maximum daily temperatures 4 degrees F warmer than the country trees, and minimum averages more than 8 degrees F warmer, driven largely by the well-known “urban heat island” effect. The warm city nights, in particular, allowed the seedlings to perform more of the chemical reactions needed for photosynthesis. The seedlings were planted in the spring and, after caring for all the trees with fertilizer and weekly watering, biomass was measured the following autumn.