Effects of pine beetle outbreak might not be as bad as predicted, experts say

By CHRISTINE PETERSON Star-Tribune staff writer

Predictions were dramatic. Streams would rise. Nutrients would be lost. Fire would ravage the red forests in ways we could only imagine.

The mountain pine beetle epidemic was severe, the worst in North America’s recorded history. It crept through mountainsides in the West and left behind a scar of red and gray trees.

As the epidemic nears its end in some areas like the Medicine Bow National Forest, some scientists are discovering their predictions may have been backward. Stream flow has not increased, and nutrients are still in the ground.

“The big trees died, but there are still residual trees left,” said Brent Ewers, a botanist at theUniversity of Wyoming and one of the scientists on the study. “These forests are more resilient to the outbreak than we thought.”

Ewers and fellow researcher Paul Brooks, a hydrology professor at the University of Arizona, presented their information recently at the fall meeting of the American Geophysical Union in San Francisco.

The researchers started studying the Medicine Bow and Roosevelt national forests in 2008 with experts from across the western U.S. They wanted to know how much stream flow would increase and how much carbon and nitrogen would flood down the mountains.

Snow falling in healthy forests collects on needles and evaporates. What falls on the ground is often used by trees before it reaches groundwater or streams, Brooks said. The rest flows into our rivers, lakes and reservoirs amounting to the bulk of the West’s water supply.

Most people believed that without trees drinking water and tree needles cradling snow to be evaporated, more water would flow down into streams, he said.

They also thought carbon and nitrogen, chemicals released from trees after they die, would pollute the water. Both chemicals in large quantities can become toxic and could have required pricey solutions at water treatment plants, Brooks said.

An increase in water and chemicals can be effects after small fires or isolated logging projects. What some scientists didn’t realize was the sheer extent of the pine beetle damage. Instead of localized fires or logging, pine beetles swept through entire mountain ranges, burrowing in large trees, laying larvae and spreading their deadly fungus.

Snow then fell in large open areas, evaporating and blowing away the same as if it had fallen on fresh pine needles. New plants and trees on the ground flourished without the big, older trees, drinking the excess water, Brooks said.

Remaining trees and plants are absorbing nitrogen, causing the forest to actually grow faster than before, Ewers said...more

I don't understand.  We were told global warming had caused the huge beetle infestation.  Global warming is bad. But then there's mother nature, who is more resilient than all the researchers and envirocrats combined.