The Lives of Dead Trees

Forest ecologist Mark Harmon has been exhaustively examining dead logs for 40 years, and he's found a complex world few people see

- BY STEPHEN ORNES PHOTOGRAPHS BY CHRIS GUNN

MARK HARMON CROUCHES LOW next to log number 219: a moss-covered western hemlock tree trunk, five meters long, lying dead on the ground in the lush green woods.

It's marked by a thin aluminum tag. The forest ecologist leans in close, his unruly white beard nearly brushing against the decomposing cylinder. Dark, flaky patches on the dull, reddish-brown wood closer to the ground show where fungi have infiltrated the cellulose within. Farther down the trunk, multicolored fungal conks protrude like hard shelves barely big enough for a mouse. A shiny black beetle scurries along the ground, then out of sight under the log. Harmon presses gently on 219 with three fingertips. It's so spongy that he is reluctant to roll back a chunk of it to reveal what lies underneath. “Oh, I don’t want to destroy it,” he says slowly. “It’s all falling apart.”

Harmon, a longtime faculty member at Oregon State University, has been watching number 219, and more than 500 other logs nearby, decay for 40 years. He has trekked to this site in the H. J. Andrews Experimental Forest, a watershed nestled in Oregon’s western Cascade Mountains, at least 100 times. He drives more than two hours on paved and gravel roads from his home in Corvallis, Ore., then hikes in half a mile through the undergrowth, carrying tape measures, scales, saws and a computer to chronicle the relentless changes. His goal: establish an exhaustive baseline dataset that any scientist could use to test hypotheses about tree decomposition or to compare patterns of decomposition in the Pacific Northwest with those in other regions.