Do heat waves affect urban trees more than rural trees?

A recent study describes how trees in New York City, Boston, and Baltimore, Maryland are more negatively affected by heat waves and drought than trees of the same species in nearby rural forests. Urban trees in all three cities experienced more negative impacts from heat waves and drought than rural trees. In addition, the growth rate and carbon storage capacity of urban trees are significantly reduced during extreme weather conditions. The growth of oak trees, but not red maple trees, in urban sites in Boston and New York City was more adversely affected by heat stress than their rural counterparts. But no such urban-rural difference in growth was observed for oak trees in Maryland. Harsh urban environments, characterized by hot, dry conditions and high pollution levels, increase the vulnerability of urban trees to climate stress. As cities grapple with the effects of climate change, this study provides important insights into how the health of urban trees and the ecological services they provide may be at risk.