In the last ten years, the federal government and rural landowners have spent increasing sums of money thinning spindly trees and removing underbrush. The aim is to reduce risk from wildfire.
A new study by the Forest Service finds that tree stands need to be "intensively" thinned for that strategy to be effective.
Study co-author David Peterson of the Pacific Northwest Research Station in Seattle says a dense tinderbox forest before thinning could have more than a 1,000 trees per acre.
"For those forests that have not experienced fire for several decades, we found that you need to reduce the density of those trees to somewhere between 50 to 100 trees per acre," he says.
Peterson says in their study, the researchers established "scientifically defensible" guidelines for the first time. The Forest Service says the findings mainly apply to the dry forests of the inland Northwest east of the Cascade crest.
The study was published in the Canadian Journal of Forest Research.
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