06 mayo 2011

Un estudio muestra que árboles afectados por escarabajos favorecen la propagación de los incendios

visto en newsvine.com

The red needles of a tree killed in a mountain pine beetle attack can ignite up to three times faster than the green needles of a healthy tree, new research into the pine beetle epidemic has found.

The findings by U.S. Forest Service ecologist Matt Jolly are being used by fellow ecologist Russ Parsons to develop a new model that will eventually aid firefighters who battle blazes in the tens of millions of acres from Canada to Colorado where forest canopies have turned from green to red from the beetle outbreak.

The new model incorporates a level of detail and physics that doesn't exist in current models, and it is much more advanced in predicting how a wildfire in a beetle-ravaged region will behave, Parsons said.

"It gives you so much more information about what to expect," he said. "Are these people safe here or should they run away? If we put a crew on the ground here, can they make it to the top of the ridge in ample time?"

Many communities in the Rocky Mountain West have beetle kill forests in some proximity.

And the new research dispels the notion that beetle-killed trees present no greater fire danger than live ones, a theory that had gained traction after a couple of wet, cool summers tamped down fire activity in the region, Jolly said.

On the contrary, beetle-killed trees can hold 10 times less moisture than live trees, Jolly found. That means they not only ignite more quickly than live trees, but they burn more intensely and carry embers farther than live trees, Jolly said.

He found that it takes less heat for wildfires to spread from the ground to the crowns of beetle-killed trees, making a wildfire in a forest with beetle-killed trees potentially much more difficult to contain.

Mountain pine beetles also start losing their moisture before the needles change to that tell-tale red, Jolly said, meaning even a healthy-looking pine tree could pose an increased fire threat to an unsuspecting firefighter.

Jolly took more than 1,000 tree moisture content measurements and conducted hundreds of ignition tests last year in four states, using foliage from trees with red, yellow, orange and green needles.

Jolly and Parsons will present their research Wednesday in Helena at a seminar on wildfires and the mountain pine beetle held by the Montana Department of Natural Resources and Conservation. The seminar will also host researchers from the University of Idaho and British Columbia, where the beetle infestation covers an estimated 43 million acres, which is more than 67,000 square miles.

"I think this is a first step," DNRC director Mary Sexton said of the new research. "I think overall this has been an area where folks are just beginning to have guidance or definite information."

In Montana, beetles are estimated to have attacked about 4 million acres of forest over the past decade. A survey taken last year shows the beetle activity may be declining in some of the most ravaged parts of the state between Helena and Butte.

But that may be because the beetles are simply running out of trees, Sexton said. Meanwhile, beetle activity in the central and northwestern part of the state is still increasing, she said.

South of Montana, the beetle epidemic has spread to about 4 million acres in Colorado and southern Wyoming, according to forestry officials.

Research hasn't been able to keep up with the fast spread of the mountain pine beetle infestation over the past decade, Parsons and Jolly said. Even now, much of the research is dedicated to the long-term ecological effects of the outbreak, something of little use to firefighters, Jolly said.

"They're not concerned with 10 years from now. They're concerned with how a fire is going to behave now," he said.

The new model isn't ready to be used by fire managers in the field, so the old models shouldn't be thrown out yet, Parson said. Only a few people in the Forest Service and collaborating institutions are using the new one, he said.

"Our hope is that this kind of modeling will increasingly become an important part of the decision-making and it will provide the science that feeds into fire management decisions," Parsons said.

0 comentarios realizados :