Study looks at ‘imperiled’ trees’ role in the valley ecosystem
By ANN McCREARY
Walking through the Methow Valley a century ago, you would find yourself in the midst of open stands of large ponderosa pine trees that dominated the landscape.
Today, only a fraction of those expansive, park-like ponderosa pine forests remain, and their loss has impacted the plants, animals and people living in the Methow Valley.
In an attempt to inventory the valley’s remaining ponderosa pine ecosystems and preserve what is left, the Pacific Biodiversity Institute (PBI), a Winthrop-based conservation organization, has launched a new study.
Ponderosa pine forests are “the most imperiled ecosystem in the Methow,” according to Peter Morrison, PBI executive director.
“Old-growth ponderosa pine forests occupy only a very small fraction of their historical extent,” he said. “We’re looking at the last fragment of what used to be the dominant landscape. Now we’re down to 10 percent or 5 percent, or perhaps only 1 percent” of former ponderosa pine forests.
“A lot of the valley bottoms that are now converted to agriculture and houses used to be big, old-growth pine, up to 6 feet in diameter,” Morrison said.
Since 2009, PBI has sponsored research in the Methow Valley on the use of large, old ponderosa pines by western gray squirrels, a species listed as threatened in Washington state. Because the squirrels live in old ponderosa pines, they have lost most of their habitat in the Methow Valley.
PBI has trained dozens of “citizen scientists” over the past four years to help locate and observe the squirrels in ponderosa pine stands. Western gray squirrels are significantly larger than other local species, with solid gray backs and a white underside.
“They are also much quieter” than Douglas squirrels, also known as chickaree squirrels because of the sound they make, said George Wooten, a botanist and PBI staff member.
“We’ve mostly concentrated on finding good habitats where squirrel nests appear,” said Wooten. “A nesting squirrel indicates a good habitat. The nest sites are used every year. The squirrels return to them. We call them ‘strongholds’ for gray squirrels.”
The PBI squirrel research indicates most of the western gray squirrel strongholds in the valley are in tributaries of the Methow River south of Twisp, clustered in limited areas where large diameter ponderosa pines are still present.
“Black Canyon has hundreds of nests,” said Wooten. “There are only a handful north and west of Twisp.”
Morrison said some gray squirrels have been found in the middle and lower Chewuch drainage, and some in Mazama. “There are isolated pockets of gray squirrels, but they are not very well connected,” he said. “They used to have a connected habitat.”
Other wildlife affected
Through the gray squirrel study, PBI has become aware of the importance of ponderosa pines to other wildlife, including white-headed woodpeckers, pileated woodpeckers and pygmy nuthatches, Morrison said. He said the squirrel study this year, which runs July-October, will expand to gather more comprehensive information about the ponderosa pine ecosystem and wildlife that are found in these forests.
“We want to look at the bigger picture,” said Wooten. That bigger picture will help researchers understand the relationship of animals to the trees, and the relationship of the trees to the overall ecosystem of the valley.
Agriculture, logging and residential development aren’t the only reasons that the old ponderosa stands have disappeared, Wooten said. Fire suppression has also played a significant role because it has allowed the growth of Douglas fir and other vegetation that not only compete with ponderosa pines but also lead to more devastating fires.
“Whenever you have tightly packed trees … there are a lot of interlocking canopies and ladder fuels,” Wooten said. “Ponderosa pine is a fire-prone ecosystem and it’s pretty well recognized that you can’t maintain a fire-prone ecosystem without fire,”
Ponderosa pines are “fire-tolerant” and mature trees are able to survive periodic fires. But, Wooten said, “in the last two decades we have seen uncharacteristically severe fires.” When fires are suppressed for years and the open pine forests fill in with other trees – primarily Douglas fir – even the fire-tolerant ponderosas can’t survive the conflagrations that result, Wooten said.
Because naturally occurring ponderosa pines stands don’t burn with the intensity of tightly packed forests, and tend to survive wildfires, they offer a more fire-resistant environment, Morrison said.
“If we could restore this old growth ponderosa pine ecosystem, we would make the community more fire-safe and restore wildlife habitat,” Morrison said. “Wildlife needs habitat connectivity. We could restore some of that connectivity.”
Looking at old maps
To assess how much of the historical ponderosa pine habitat is left, researchers from PBI have turned to old maps of forests in the Methow Valley. A survey of forests in 1898 was conducted to prepare for the establishment of the federal forest service, Wooten said. “At that time the forests were seen as a reserve” to provide wood needed for naval ships or other national interests, Wooten said.
An inventory of forests in 1936 mapped large diameter pines for logging purposes. Most of those stands are gone today, “either logged or out-competed by Douglas fir,” Wooten said.
Gathering information about the current condition of ponderosa pine forests will help PBI develop proposals to conserve and restore the stands, Morrison said.
The effort would have “multiple objectives,” he said. “We’re interested in a partnership that would inspire and stimulate more pine restoration … to make the community more fire safe and restore wildlife habitat. We’re not saying we should turn everything back into forests. But there’s a lot that could be done to make it a more enjoyable place for humans and wildlife.”
Because the pine forests grow on federal, state and private lands, conservation and restoration would need to involve a wide range of participants, Morrison said. “First we’re going to see what level of interest there is out there,” he said.
In its ongoing study of gray squirrels and their habitat, PBI invites volunteers to participate in the research. Volunteers receive training in using wildlife cameras, hair-tubes to collect fur samples, GPS and vegetation maps. For information about volunteering contact PBI at firstname.lastname@example.org or call the office at 996-2490.