WASHINGTON — Can a plague of beetles change the weather?

That's one question researchers hope to answer in a four-year research program in Western forests that are being infested by pine mountain beetles, leading to the deaths of great swathes of trees.

Vegetation affects local weather by absorbing or reflecting sunlight and releasing chemicals and moisture. Changes can influence such things as rainfall, temperatures and smog.

Scientists from the National Center for Atmospheric Research in Boulder, Colo., have launched an effort to study the interaction between the surface and the atmosphere in a region extending from southern Wyoming to Northern New Mexico using aircraft, ground-based instruments and computer models.

"Forests help control the atmosphere, and there's a big difference between the impacts of a living forest and a dead forest," NCAR scientist Alex Guenther, a principal investigator on the project, said in a statement.

"With a dead forest, we may get different rainfall patterns, for example," he added.

Tiny particles from plants can form the nucleus for raindrops. Plants also emit chemicals that can help form smog. Living forests soak up carbon dioxide, while dead ones release it, potentially contributing to warming.

Indeed, preliminary computer modeling suggests that beetle kills of large forest areas can lead to temporary temperature increases of 2 to 4 degrees Fahrenheit, the researchers said.

The project is known as BEACHON, for Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen.

It is funded by the National Science Foundation and participating organizations include Colorado College, Colorado State University, Cornell University, Texas A&M University, and the universities of Colorado, Idaho, Minnesota, New Hampshire and Washington as well as the U.S. Forest Service, the Environmental Protection Agency and universities in Austria, France and Japan.

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www.tiimes.ucar.edu/beachon