CORVALLIS - Efforts to recover threatened coastal coho salmon, if they're to be effective, need to focus less on forest management and more on the impact of land uses along the lower reaches of rivers, researchers said today at Oregon State University.
Some of the state's scarcest habitat - the oak savanna that historically comprised the Willamette Valley foothills - is not protected by law. Old-growth forests are also less abundant than they've been historically, although they should increase in the future. However, there's a looming shortage of diverse young forests - where seedlings intermingle with fallen logs, standing dead snags, and shrubs - that provide specialized habitat for certain animals and plants.
These and other findings were presented today at an OSU conference on Oregon's forest sustainability. Scientists from OSU and the Pacific Northwest Research Station of the Forest Service discussed forest conditions today and what's likely to change in the next 100 years.
They unveiled results of studies on timber supply, forest habitat for fish and wildlife, the state of forest soils and water, contributions of forests to carbon in the world's atmosphere, and community benefits from forests.
Coho salmon habitat depends heavily on the landscape through which the rivers flow, said Forest Service fisheries biologist Gordon Reeves. In his studies of the Tillamook and Nestucca rivers, Reeves found that the land with the best potential coho habitat lies mostly along lower rivers, which were among the earliest to be settled by European-Americans and have undergone profound changes in plant life, water tables, and other key habitat qualities.
"If we're going to be successful at sustaining coho numbers, we need to focus lower in the watershed," said Reeves. "Land use in the valleys may be of much greater consequence to coho recovery than timber management in the higher elevations."
According to Forest Service ecologist Janet Ohmann, settlement and development of the Willamette Valley foothills has greatly reduced the quantity of grassy, oak-dotted prairie that once dominated the lower-elevation landscape. These oak savanna ecosystems are important habitat for rare prairie grasses, flowers, and insects, yet they are not protected by law.
"Forest types are unevenly protected across the landscape by both land-use laws and management policies," said Ohmann.
Old-growth forests in the Coast Range have declined from a rate of 25-75 percent over the past several thousand years to less than 5 percent today, said Forest Service ecologist Tom Spies. But because of a shift in priority from timber harvest to preservation and restoration, the federal forests are expected to have more old growth in the future than today.
However, there's a looming gap in diverse, young, early-successional conifer forest, the type of forest that once came in naturally after forest fires.
These young forests, up to 10 years old, have a diversity of forest structures - fallen logs and dead snags - and a diversity of plant life. They are important habitat for the western bluebird and other birds that prefer open areas, as well as some shrub species. Today, because of intense timber management on private lands, young forests don't get the chance to develop much diversity.
"The federal lands are growing old trees," said Spies, "and private landowners usually want to get the seedlings growing as fast as possible by eliminating competitors."
Projections of the distribution of Oregon's population growth show significant growth in the Portland-Salem corridor, but a large majority of Oregon's coastal forests should stay intact, according to a 100-year projection of how population growth will affect Coast Range land cover. Forested area will decline by a little more than 15 percent, says K. Norman Johnson, a policy analyst with OSU's College of Forestry, from 3.3 million acres today to about 2.85 million acres in 2095. Most of the loss will occur in forest fringing the Willamette Valley as land is developed for urban use and suburban residences.
"But the bulk of our Coast Range forest will remain," Johnson said. 'The greatest unknown is the degree to which we will see a sprinkling of homes in the remaining wildland forests, and how that in turn will affect commercial forestry in the Coast Range."
Other key findings presented at the conference:
- Coastal Oregon has great intermingling of owners, and patterns of forest structure are strongly linked to ownership and historical land use. Protecting biodiversity in the Coast Range will require a conversation among a diversity of players.
- A large proportion of Oregon's timber, about 75 percent, is harvested from forest industry lands. Harvest from state-owned and non-industrial private lands makes up most of the difference. Federal lands are supplying almost no timber.
- Current trends point to a shortage of maturing forests, 100-200 years old, that will occur several decades in the future. Trees on private forest lands are usually harvested before they reach 100, and as the maturing forests on federal lands reach old-growth age, there will be fewer younger trees to replace them. Maturing forests provide good-quality habitat for fish.