Air pollution may not deplete forests but could affect their diversity

Science : Although ground-level ozone has long been recognized as dangerous for human health, its effect on plant life has not been as clear. Now Manuel Lerdau of the University of Virginia in Charlottesville and colleagues have used computer modeling to assess the impact of ozone on forests. The researchers focused on the vulnerability of several key tree species native to the southeastern US. Lerdau’s team ran two computer simulations of forest growth over a period of 500 years, one with no exposure to atmospheric ozone and the other with an ozone level of about 80 parts per billion, the current air quality standard set by the US Environmental Protection Agency. Although the total tree mass remained about the same in both simulations, the ozone-exposed forest ended up with fewer species. The researchers conclude that forests exposed to air pollution should maintain their ability to absorb carbon dioxide. But less diverse plant populations, such as croplands, may prove more vulnerable.