Our Changing Forests: An 88-Year Time Lapse

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Intense forest fires have been raging across the western United States this summer. So far this year, nearly 43,000 wildfires have torched almost 7 million acres of land. As NPR Science correspondent Christopher Joyce and photographer David Gilkey report from Arizona and New Mexico this week, the forests of the American Southwest have become so overgrown that they're essentially tinderboxes just waiting for a spark.

Intense forest fires have been raging across the western United States this summer. So far this year, nearly 43,000 wildfires have torched almost 7 million acres of land.

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As NPR Science correspondent Christopher Joyce and photographer David Gilkey report from Arizona and New Mexico this week, the forests of the American Southwest have become so overgrown that they're essentially tinderboxes just waiting for a spark.

This "tree epidemic" stems from Forest Service policy dating back to the early 1900s of aggressively fighting all forest fires. But regular, small fires clean out dead wood, grasses and low brush — and if fires are quashed, the forest just grows into fuel. And that's why we see more of these mega-conflagrations today.

In trying to tell the story of our changing forests, we turned to the U.S. Forest Service for some historical context. Buried in the back of General Technical Report No. 23 was the pay dirt: a stack of 13 series of photos, more than 88-years in the making.

The photographs document the life of the Bitterroot National Forest in west-central Montana, from 1909 to 1997, though the project is still ongoing. Every 10 to 15 years, photographers return to the same 13 spots in the forest.

Bitterroot is a managed forest — meaning that foresters periodically trim, cut and thin the land — and the photo series is meant to show how dynamic the forest is with management, says Michael Harrington, a research forester with the Missoula Fire Science Lab. Through the nine-image sets, we can see trees grow and thicken, the effects of selective logging and also how quickly the forest land rebounds.

Article continues with photos at NPR Topics: Environment

Dry forest image via Shutterstock