By Evan Bush
Scientists are using cutting-edge research in their efforts to restore Southwest Washington’s Ellsworth Creek Preserve, in hopes of easing the impacts of climate change.
Standing between nearly uniform rows of hemlock trees, scientist Tiara Moore clutched a tiny vial of evidence.
Filled with dirt and no bigger than her pinkie finger, the vial contained traces of hundreds, perhaps even thousands of creatures that had oozed by, crawled past or fluttered into this tiny corner of the Ellsworth Creek Preserve.
The microscopic flecks of DNA — from insects, amoebas and mushrooms — could help tell the story of a forest trying to regrow to its former might.
These forest forensics, part of a fast-growing field called environmental DNA, will tell researchers what’s living here, which, in turn, tells forest managers if what they’re doing is working here.
The soil where Moore dug for DNA was once rooted with old-growth trees common across the coastal Northwest, before decades of clear-cutting stripped them from the land.
Restoring landscapes like these helps take up and store more carbon, part of the solution to reduce the impacts of climate change.
The Nature Conservancy, a nonprofit which owns about 8,000 acres at Ellsworth, hopes Moore’s work can help in pursuit of a longtime Northwest quest: to restore its old-growth forests — rich with biodiversity — and fast.
“These are some of the most carbon-rich systems on Earth,” said David Rolph, director of land conservation for the organization in Washington. “Could we rebuild?”
The conservancy’s theory — backed by years of Northwest forest science — was that thinning and mimicking nature would create a more complex, vibrant forest with a diversity of species, more light for trees and less competition among them for nutrients.
“Any modeling you do will show you get bigger trees faster with thinning,” Rolph said. “You can manipulate and accelerate that complexity.”
The larger the tree, the more carbon can be absorbed and stored, making old-growth forests a boon to mitigating climate change.
By PASSANT RABIE
Bigleaf maple trees in Washington state are on the decline. Researchers are on the hunt for the cause, and climate change is turning into a lead suspect.
Daniel Omdal has driven past the same bigleaf maple tree for decades, often stopping his car to take pictures of its full, expansive crown. In the past few years, however, the tree has started to look more lopsided, with bare branches and patches in its crown with little to no growth.
To Omdal, a forest pathologist, it seemed like an obvious case of an insect infestation. If not, perhaps some kind of disease: a damaging fungus, wilt or a rogue bacterium. Whatever it was, it wasn’t isolated to one tree. The extent of sick bigleaf maples was alarming, and Omdal wasn’t the only one who was worried.
Omdal’s colleagues at the Washington State Department of Natural Resources, where he has worked since 1997, had noticed the same symptoms in many other bigleaf maples. So had many residents of the region, who called the state to report their concerns. The issue had also been occurring nationwide, with reports of sharp declines of urban tree populations in different states, such as the oak tree in Southern California. In Washington, the problem was hard to miss: Bigleafs, also known as Oregon maples, are a staple of the Pacific Northwest landscape.
“These calls became more frequent, I couldn’t so easily dismiss the concerns,” Omdal says. In 2011, he became part of a state-led team investigating the bigleaf die-offs.
The group discovered that about 40 percent of bigleaf maple trees in Washington state are declining, says Jacob Betzen, a graduate student at the University of Washington’s School of Environmental and Forest Sciences, who has been working with the investigative team for the past two years.
The first suspect on their list was Armillaria, a fungus that causes the roots of the tree to rot. But when the team tested hundreds of trees for it, most of their results came back negative. Then, the researchers tested for another fungus called verticillium wilt. Also negative. Often, a few trees would be infected, but it was never widespread enough to be the primary cause of the species’ decline.
Omdal collected soil samples to test in the lab to look for other causes. Every time his team followed a new lead, it didn’t pan out. “We would come to a dead end,” Omdal says.
Patrick Tobin, Betzen’s advisor and a specialist in disturbance ecology, added, “It’s been puzzling, there’s no smoking gun here.”
Then Betzen noticed something curious about the die-offs. They are much more common in developed landscapes and areas that are warmer, drier and closer to roads. That led to a new suspect: climate change. “It seemed probably related to recent weather patterns, it’s getting hotter and drier in Washington in recent years,” Betzen says. The group’s results won’t be published until Betzen concludes his research at the end of the year, but Tobin is confident that the key driver causing bigleaf maple die-offs is, in fact, climate change.