Looking at old growth from new angles; from treetops to roots, aging woods still hold plenty or surprises for researchers

National Wildlife, Dec-Jan, 1997 by Kathie Durbin

From treetops to roots, aging woods still hold plenty of surprises for researchers

On a drizzly morning last April, scientists Jim Lewis, Bob McKane and Peter Beedlow head for a laboratory unlike any other in North America. They walk through a forest of 500-year-old conifers to a giant construction crane. They don harnesses fitted with carabiners, haul sophisticated electronic gear aboard the crane's gondola and attach themselves to rings on the gondola's inner walls.

Traveling from forest floor to forest ceiling is a smooth, fast trip--an elevation gain of 220 feet in two minutes. The researchers can see nearby Cascade peaks, clear-cuts, tree plantations and the Wind River flowing through a corridor of budding alders. From up here, it's easy to see where old growth ends and the bright, even-topped younger forest begins. Old-man's beard, a pale-yellow epiphyte, hangs from venerable Douglas firs, hemlocks and cedars. Broken crowns of live trees punctuate the green canopy with splashes of orange heartwood. Stark gray fingers of dead snags point skyward. Silviculturists call the canopy's exposed branches "sun foliage" because they get more light, wind and extremes of temperature. That affects how they grow--their "bunchiness."

Swaying gently, the open-air elevator rises past the tips of old-growth Douglas firs and enters a world of sky and clouds. It is silent up here where most of the forest's essential processes occur--where the sun's energy is captured and the cycling of water from soil to atmosphere is regulated.

Below is a rolling, uneven forestscape of widely spaced conifers, with clear views of melting snowbanks on the ground. "What strikes me is how uncanopylike the canopy is," says Beedlow, a U.S. Environmental Protection Agency (EPA) ecologist. "When you walk around on the forest floor, you don't get the same sense of its roughness." Scientists have even invented a word--"gappiness"--to describe the uneven treetop topography.

Changing attitudes: Such observations are signs of a new era in forest science, which today is teaching us how much more there is to a tree than sawtimber, how much more there is to a forest than trees. As recently as the 1970s, research in the Northwest's forests was preoccupied with finding efficient ways to cut down old trees and replace them with young plantations. Now, managers are understanding that a century of overcutting, fire suppression and livestock grazing has left many forests in deteriorating condition and many wildlife species in decline.

As part of that growing awareness, the Clinton administration is pushing to implement ecosystem management in the Pacific Northwest, the Interior Columbia Basin, California's Sierra Nevada and Alaska's Tongass National Forest. "Increasingly, we are studying large-scale integrated issues about the management of land--issues that have not only a biological but a socioeconomic component," says Thomas J. Mills, director of the U.S. Forest Service's Pacific Northwest Research Station.

Such approaches may have their pitfalls. Resource specialist Rick Brown of the National Wildlife Federation worries that some specific wildlife species may fall through the cracks. "Ecosystem-level approaches are essential, but when you have a landscape that has been hammered, and so many species are at risk, you have to look at their individual needs," he says. Still, forest science overall is moving far beyond its old goals, and it is yielding a treasure trove of findings, some of which may have direct implications for forest management.

Because ecosystem management asks land managers to design timber sales that emulate nature, researchers are taking a closer look at natural disturbances such as floods and fires. For instance, fish biologists, hydrologists and geologists collaborated on recent studies of Pacific Northwest floods. In one case, Forest Service researchers Fred Swanson and Gordon Grant compared the effects on one forest of two floods, in 1964 and 1996. They found that although the 1964 flood was less severe, it triggered more landslides, reshaped more river channels and dumped more silt into streambeds.

The reason may be related to a halt in logging at the study site. Just prior to the 1964 flood, the site had experienced 15 years of logging and road construction. "But leading up to 1996," says Swanson, "we'd had virtually no road construction and no logging."

A 1995 study of the fire history of three Oregon coastal watersheds by Forest Service fish biologist Gordon Reeves and colleagues found that before aggressive fire suppression began, wildfires in the region typically altered forest composition across entire watersheds. In contrast, fire is virtually unknown in the wet Alaska rain forest, where the main sources of natural disturbance are landslides and windstorms that topple small stands of trees.

One conclusion to be drawn, according to Mills, is that maybe logging in the Northwest should take place intensively, one watershed at a time. In Alaska, conversely, researchers are now studying the ecological effects of logging that creates smaller openings in the forest.