Forests' dying trees sparking concern in West

Pine and fir trees are dying at double the rate of 1955 in the Western United States, victims of rising temperatures, more frequent droughts and a bark beetle infestation.

The phenomenon is sparking concerns about the ability of temperate forests to withstand global warming, U.S. Geological Survey researcher Phillip van Mantgem said. All species in the region, including hemlocks, pines and firs, face the added risk of fire from temperatures that have risen as much as 0.9 of a degree Fahrenheit a decade since the 1970s.

Should temperate forests become sparser as trees continue to die early, timber prices will rise and water, habitat and carbon-dioxide storage problems may occur. Societies should look more closely at how to live with the changing forest, including restricting housing construction near fire-prone woods, University of Colorado geography professor Thomas Veblen said.

"We have to start thinking outside the box as a society to adapt to the changes that are under way," said Veblen, a specialist in forest ecology who along with van Mantgem helped co-write a paper published in Friday's journal Science.

The researchers looked at possible causes for the trees dying earlier than past years, including rising density within forests, pollution and climate change. As the region warmed since the '70s, they discovered a corresponding increase in trees dying early.

In Colorado, temperatures have risen in sub-Alpine regions up to 10,000 feet high, which have suffered through a drought for more than a decade, Veblen said. In addition, beetles, which benefit from warmer temperatures, have killed more than 90 percent of the lodge pole pines in northern Colorado, the researchers said.

As the risk to forests rises, demand for wood, paper and cardboard is growing in a "practically linear" relationship with population expansion, said Geneva-based Pictet & Cie, which operates a timber fund.