Philip Larkin started a poem that way, but it’s good advice for the Forest Service, too. We’ve long known that fire plays an important role in maintaining forests, prairies and other natural ecosystems.

A new set of studies show that thinning forests without burning makes subsequent fires more dangerous:

Thinning forests without also burning accumulated brush and deadwood may increase forest fire damage rather than reduce it, researchers at the Forest Service reported in two recent studies.

The findings cast doubt on how effective some of the thinning done under President Bush?s Healthy Forests Initiative will be at preventing fires if the forests are not also burned.

Fires feed on the layer of duff that builds up on forest floors, and thinning makes it easier for oxygen to get to a fire. Regular burning reduces the levels of duff, so that the fires are less intense. That means they kill fewer trees and are easier to control in populated areas.

Federal policy since 2003 has pushed thinning of forests as the major tool of forest management, and de-emphasized prescribed fires. It was claimed that regular thinning could control fire frequency and intensity, but it appears that the “healthy forests” plan is probably making them less healthy.