Study says urban trees are more resilient than rural trees

Trees in urban areas are actually thriving better than those in rural areas, Matt Simon reports for Grist. Trees in urban cities are vulnerable to vandalism, pests and diseases, and the heat island effect — the phenomenon of cities being warmer than rural areas at night because concrete traps heat. But a new study led by ecologist Zhengfei Guo at the University of Hong Kong shows they are more resilient to stresses like extreme heat than their country counterparts.

The study shows that urban trees lose less green vegetation, recover faster from losses and experience longer growing seasons. Researchers said this may be because urban trees are better tended to, or because there are surprising advantages to how cities are structured. They add that urban areas are harsher in terms of pollution and air quality, but crews in cities consistently tend to intentional green spaces and advocate for ways that residents can keep them healthy.

Cities tend to funnel water into sewers as quickly as possible to prevent flooding and pooling on top of concrete. When rainwater cascades, the only place it can collect, if not on concrete, is in green spaces. For hydrated plants, high heat due to the heat island effect can provide extended growing seasons, although such heat is harmful to human health.

“Urban vegetation is often pampered compared to what’s growing wild in the countryside,” Simon writes. “This is an advantage in the long term, but doubly so during relentless droughts and increasingly miserable heat waves. While rural trees desiccate, their compatriots in cities are regularly attended to.”

Jin Wu, coauthor of the study, said that even though urban trees are resilient to extreme environments now, they won’t always be. Cities are already taking steps to stock up on native seed species and saplings that fare well in heat in other parts of the world, and cities like Los Angeles are reimagining their water systems.