WIND RIVER EXPERIMENTAL FOREST — Suspended from the arm of a construction crane in a bright yellow gondola, to which we are securely attached with climbing harnesses, we rise swiftly from the ground, leaving the dark, moist forest floor behind.
“‘We’re down here in a nice, cool, verdant fore
st,” says Ken Bible, a University of Washington forester and site director at the Wind River Canopy Crane, who is serving as our tour guide. “As we ascend, the environment will change. You’ll see the change almost immediately. And everyone gets a window seat.”
The seven in our group are the last voyagers to ascend by gondola 250 feet into the treetops at the Wind River Experimental Forest north of Carson, in the Gifford Pinchot National Forest.
The Wind River Canopy Crane fell silent May 27, after 16 years of ferrying scientists into the forest canopy. There, they had unprecedented access to a 500-year-old forest and the ability to maneuver from tree to tree within a 560-foot circle.
Forest managers cite the cost of operating and maintaining the crane and declining interest in canopy research as reasons for shutting down the crane.
A rare view
Our first stop, about 30 feet up, was in the mid-canopy, where the forest opens and light pours in. Here you can see the shapes of the firs, cedars and hemlocks and the “gappiness” of the spaces that separate them, a term coined here at the Wind River facility. These gaps in the stand create flyways for birds and flying squirrels.
Farther up, we “trolleyed” past a very tall grand fir. Bible pointed out the seed cones and pollen cones dangling from the tips of the branches, signaling new growth.
Next stop: The canopy, where we looked down on a forest inhabited mainly by spiders and mites and the occasional raptor in search of prey. Familiar trees look different up here. From above, the western hemlock, which grows to a height of 165 feet, looks like an open green parasol. Douglas fir needles grow in brushy, spruce-like clumps. Western red cedars have looping, graceful branches loaded with cones.
The canopy world is a dry world — scientists call it “desiccated.” Water from the roots must travel more than 200 feet to reach the crowns of the conifers. Mistletoe has colonized many trees, forcing them to grow new tops. A tall Douglas fir thrusts a black spire into the sky. Dead at the top, alive below, it was a partially killed by standing water from an ephemeral stream.
The gray-green lichen known as “old man’s beard” droops from the limbs of the Douglas firs.
“The tree doesn’t get anything from it, but the lichen gains structure,” Bible says. “The lichen gets a free ride.”
Bible and the scores of other scientists who have worked in the canopy have come to know these trees very well. Each of the 2,000 trees in the experimental forest plot has a number. About 300 of them were reachable via the crane.
Before the crane, biologists and other researchers had to use climbing equipment to scale the tall conifers. Once there, they couldn’t move from tree to tree. That spirit of adventure survives; one student from The Evergreen State College recently tied himself to a tree for days to study which lichens birds use to build their nests.
Managed jointly by the Forest Service Research Lab, the Gifford Pinchot forest and the University of Washington, the crane has enabled biologists to study bats and birds and flying squirrels, and to learn more about how old-growth trees store carbon, circulate water and waste, and resist pests and disease.
Research under way at Wind River since 1999 has allowed scientists to gather the world’s longest continuously collected set of data on carbon flow from a forest. That data indicates that this particular forest is a slight carbon sink: It takes up more carbon when trees put on new growth in spring and summer than it releases through decay.
It’s in balance, Bible says; its nutrients and growth patterns are “locked in.”
University of Washington forest ecologist Jerry Franklin, who led the effort in the 1990s to win funding for the $1 million project, says work at the crane confirmed what he and other scientists had suspected as early as the 1980s: that old-growth Douglas fir forests weren’t emitting more carbon than they were absorbing — making them an important tool for reducing greenhouse gases.
Old-growth trees don’t stop growing, but in trees that have survived 500 years, most of the foliage growth occurs at mid-canopy, not at the top. These survivors can repair themselves when attacked by mistletoe and other parasites. Some have been heavily infested for 100 years yet remain vigorous.
But how these giants circulate water was until recently a mystery.
Conifers 200 feet tall take up water slowly. Imagine drinking through a very long straw. “The higher up we go, the harder it is to transport water,” Bible says. That’s why needles grow more slowly near the top. At that height, he said, “it takes a lot of force to draw the water up.”
Forest Service research ecologist Rick Meinzer studied how very tall trees get the water they need to survive centuries of environmental extremes. He discovered that during annual cycles of summer drought, trees rely on internal water storage to stabilize the supply of water to foliage high in the canopy, and depend on their deep roots to bring water close to the surface to feed shallow roots that might otherwise die every summer.
From the gondola, a few dead brown snags punctuate the green canopy. They’re an important part of the ecosystem, too.
“A lot of the bird diversity is in these hard snags,” Bible said. For birds like the nuthatch, a dead snag is a banquet of insects.
Though the threatened northern spotted owl inhabits old-growth forests, this patch north of Carson and east of the Yacolt Burn, set aside for research, is not large enough to sustain a mating owl pair. “The spotted owls don’t make it for very long,” Bible says. “There’s not enough food for them.”
Even after 16 years, there are moments of transcendence. Bible remembers going up into the canopy at night with other scientists to measure respiration in the absence of photosynthesis. Fog rolled in, and the tips of trees on the surrounding ridgetops poked through the mist. It felt like being on a mountaintop.
On hot summer days, at the very top of the canopy, ballooning spiders “float on the air, like boats on a lake,” he said.
He also recalls the day he and some colleagues spotted hairstreak butterflies in the canopy. The small brown butterfly lays its eggs in mistletoe clumps in the tops of hemlocks.
“All of a sudden, the hairstreaks came swarming,” he said. “It’s called hilltopping. We were very surprised they could lay eggs at this exposed elevation.”
Researchers and students using the crane have generated more than 250 scientific publications.
One of the last projects underway at the crane was a study of lichens designed to measure concentrations of heavy metals in a transect stretching from the Wind River forest all the way to Portland.
So why close the canopy crane down?
“The crane has taught us a lot,” Bible said, “but we’re probably at a point where there’s not a lot more it can teach. It probably has outlived its usefulness.”
The decision came only after three years of reassessing, Bible said. The partners looked at trends in research funding and research proposals. They looked at the cost of maintaining the crane and paying a full-time crane operator.
“The direction of research is toward studies that are regional and continental and global in scope,” Bible said. “Carbon dynamics and climate change are at the top of the list.”
And with climate change, there’s increasing interest in the incidence of wildfires and the spread of insects and other pests.
The tower, fitted with sophisticated equipment including an optical camera, a sonic anemometer that measures air flow, and an infrared gas analyzer, will remain. This equipment will transmit data allowing researchers to track carbon dioxide in the ambient air and alerting them to precisely when the forest begins to green up in spring.
Two major research projects are gearing up to study the forest at ground level. A study sponsored by the Smithsonian Institution Global Earth Observatories will use detailed data collected by monitoring 14,000 separate trees and shrubs at Wind River to learn more about changes in tree development.
And recently, the site was chosen as the Pacific Northwest core site for the National Ecological Observatory Network, known as NEON, a major new initiative of the National Science Foundation.
The crane has obvious value as an educational tool, but the Forest Service has no money for that, Bible said.
“And frankly, this crane is getting old,” he said. “This past year, we’ve had four stoppages.”
Mark Creighton, who has operated the crane from day one, is sorry to see it go. He’ll be returning to city work, operating construction cranes on high-rise buildings.
Worldwide, only a few canopy cranes continue to operate, he said, back on the ground after his last trip into the treetops. The one at Wind River “is the biggest one, and the only one in a conifer forest. And they’re going to shut it down for nickels and dimes.”
“It’s not about maintenance,” he said. “The crane runs perfectly. And it’s not about diminishing interest. It’s a lack of research dollars.”
In his 16 years at Wind River, “I’ve had people tell me this is the best experience they ever had,” Creighton said. “But no one will ever get to do this again.”
“We’ve given that experience to thousands of people,” Bible noted.
He’s been into the canopy hundreds of times. It’s not that he’s tired of it, he said.
“The thing I will miss is taking people up for the very first time and seeing the wonder in their eyes.”