Why The Northwest Will Continue To See Large Wildfires
The large Taylor Bridge fire that burned in central Washington is now 100 percent contained. Now, forest scientists say Northwest residents should brace for more such large fires. Munching insects, parasitic plants and global climate change are part of the problem.
Karen Ripley's job with the Washington Department of Natural Resources means she manages forest health. She stands on Blewett Pass, amid large ponderosa pines.
“If you read the journals of the early settlers, if you read the early explorers and pioneers this is really the forest they were most familiar with," Ripley says. "They could drive their wagons through this forest, they could ride a horse at a running speed.”
What she means is this: These ponderosa pines are huge, tall and spaced out. In the settlers’, time this would have happened naturally through forest fires that burned low along the understory and bases of the trees. Also, back then Native Americans regularly set fires to improve their defenses and food sources.
Today, in this particular area it’s been managed to look like those old forests. Large trunks rise up out of low grass. There isn’t much litter on the ground, or many green shrubs that fill the void between grass and tree tops.
“The effect has kind of been to take a very crowded stand and daylight the most historic, largest trees out here," she explains. "Not only has that allowed a nice grass understory to grow, it’s also protected this stand from the potential damage that a fire would cause.”
But not all forests have been managed like this. Up the forest road not even a mile, Ripley gets out of her aging sedan again. It’s thick with trees tight together -– so no tree gets enough water.
The overcrowding also makes it easier for pests to jump or fall from one tree to another. And there’s lots of insect damage. They eat the soft shoots off the branches and under the bark to where the tree transports its food and water.
“These small trees really get hammered from the rain of caterpillars coming down from up above.”
Ripley says all of this adds up to big fires –- like Taylor Bridge.
On an overlook point off of Highway 97 between Liberty and Ellensburg, grasshoppers crackle in the nearby rock. To the west is the edge of the Taylor Bridge Fire. Ripley points to where dense stands have burned to a crisp and where trees further apart appear singed with their green crowns in tack.
“Forest management does make a difference in fire behavior in all but the most extreme cases,” Ripley says.
One hundred years of fire suppression and management for timber harvest has left the landscape altered. She says these fires will only become more common with global climate change which will warm these areas making the forest dryer and more susceptible to pests.
At the same time she says there are limited funds for managing these forests, and cleaning up the combustible understory, small trees and shrubs that are contributing to fires like this month’s Taylor Bridge.
Copyright 2012 Northwest Public Radio