Ground-level ozone pollution(O3) and climate change have become key global problems threatening the environment and sustainable development of urban forests. At present, various studies have assessed the O3 impacts on trees; however, it is difficult to accurately evaluate the complex ecological effects caused by multiple factors on the natural urban environment. In this paper, the interactions between O3 and carbon dioxide(CO2), drought, nitrogen deposition, and warming, as well as the effects of the physiology, biochemistry, and growth of urban trees in China were reviewed. Elevated CO2 could alleviate the negative effects of elevated O3 on the photosynthetic metabolism, antioxidant system, and growth of trees. There is a complex interaction between O3 and drought, which may synergistically aggravate, alleviate, or have no effect on trees. However, there was no correlation between O3 and N deposition, only a significant interaction between elevated temperatures and O3, which slowed down the adverse effects of O3 on tree growth and photosynthesis. Finally, suggestions are put forward to manage and sustainable develop urban forests in China under future climate change and air pollution.
Keywords: combined stresses; drought; elevated carbon dioxide; ground-level ozone pollution; nitrogen deposition; urban forests.