Climbing to a New World
Could old-growth forest canopies hold the secret to keeping biodiversity, and our planet, intact? Botanist Steve Sillett ’89 has been researching up in the trees to find out.
Steve Sillett ’89 has scaled some of the world’s tallest trees—from the giant sequoias of the Sierra Nevada and the redwoods of northern California to the strangler figs of the Costa Rican cloud forest and the mountain ashes of Tasmania. But his tree climbing started right here at Â鶹¹ú²úAV, where he destressed from lab work by ascending the Douglas firs around campus.
Tree climbing became more than a hobby when Steve and a group of friends spent a fall break in the redwoods. There, without equipment, Steve scaled one of the smaller trees and used its branches to jump to another, bigger redwood nearby. He entered its upper layer, referred to in ecology as the canopy, and, up that high, more than 200 feet off the ground, discovered a whole new world. Steve could see the tops of trees all around him, going for miles, and the ocean in the distance. The canopy was home to an ecosystem of its own, with ferns and lichens and berries growing in pockets of soil on the bark. He felt transformed. “Once you get up into the canopy, you can see that the individual trees are doing so much. I mean, imagine erecting a scaffolding in the sky that lasts for a millennium, and it just continually grows and produces surfaces upon which other organisms can flourish,” Steve says. “It’s just an amazing spectacle.” Steve stuffed some of the plants growing on the tree, called epiphytes, into his shirt pocket, and, when he returned to Â鶹¹ú²úAV, showed his findings to his thesis adviser, Prof. Bert Brehm [biology 1962–93]. Bert was horrified to learn Steve had climbed into a redwood’s canopy without ropes and connected him to Oregon State University ecologist Bill Denison, who taught him rudimentary skills in tree climbing. Steve has been climbing trees—safely—ever since.
That venture into the redwood’s canopy would lead to an entire career investigating the unique realm that exists high in the trees. In particular, Steve’s research, which he’s been conducting at California State Polytechnic University, Humboldt (previously Humboldt State University) for the past 30 years, focuses on the biodiversity of old-growth forest canopies. Old-growth forests, safeguarded from logging and other disturbances, have developed over a long period, and, because they’ve remained untouched, contain distinct ecosystems unlike ones seen in younger, unprotected forests. “The old-growth forest is a special place, particularly the canopy—it’s just spellbinding,” Steve says. “There’s a lot of things that go on up there that are kind of missing from the vast majority of our landscapes today because we liquidated all the old growth. So the challenge now is to take the lessons from these ancient trees and try to restore some of these habitat characteristics.”
Steve’s team has been exploring younger forests, too, to compare their characteristics to ancient trees. They’ve found a huge gap between younger and older trees, not only due to age and time, but also because younger trees now have fewer opportunities to develop those complex ecosystems, due to the climate being drier and hotter than ever before. But the team has also found gaps between ancient trees, too—one will have a garden of epiphytes in its crown, and the one directly next to it will be barren. Part of Steve’s research involves figuring out why that inconsistency occurs, even between trees close in age.
Three decades later, Steve is still climbing trees for his research, even though new laser technology makes it possible to map trees from the ground up into their crowns. He says the old methods are still valuable for understanding the intricate world of giant trees and the forests they create—up in the canopy, researchers can figure out the specifics of trees’ leaves, bark, epiphytes, and more. And, as the climate worsens, Steve finds the work more important than ever. He hopes other people take on the task of helping to save our earth just as seriously as he does. “I’m real worried about the fate of the planet and the ability of trees to continue to do what they do,” he says. “I think the important thing is that we each try to make a contribution that could be meaningful . . . let’s focus on the task at hand, which is to keep the biodiversity from collapsing, and to keep the planet habitable.”
Tags: Alumni, Climate, Sustainability, Environmental, Research