Pacific Northwest Research Station

Forest Landscapes and Ecosystems

2008 Science Accomplishments

Sandy River responds well to Marmot Dam removal

The Marmot Dam on the Sandy River in Oregon was breached on October 19, 2007, to improve habitat for salmon and steelhead. Credit: Gordon Grant

Scientists found that an energetic river can efficiently incise and remove very large volumes of unconsolidated stored sediment, even under very modest flows. Most of the channel changes occurred upstream of a bedrock gorge, with only limited changes downstream. The Marmot dam removal clearly demonstrates that under the right set of circumstances, dam removal can be an effective strategy for restoring ecosystem function and connectivity to large rivers, and improving conditions for threatened and endangered species.

The results from this project will guide future dam removals for the next decade. It is also a superb example of meshing an engineering challenge with a scientific opportunity to deliver understanding for future use, all within the framework of a dynamic and open public process.

Partners: Graham Mathews and Associates, Johns Hopkins University, National Center for Earth-Surface Dynamics, National Science Foundation, Oregon State University, Portland General Electric, Stillwater Sciences, University of Oregon, U.S. Geological Survey

To learn more, contact Gordon Grant at ggrant@fs.fed.us.

Small streams are important sites for nitrogen uptake and processing

Nitrogen is an essential element for life, and historically the Pacific Northwest has had a limited supply. Humans have increased the supply through fossil-fuel combustion and fertilizers. Some of this excess is taken up by soils, but much enters aquatic ecosystems where it can be transported far downstream, potentially leading to noxious algal blooms and oxygen-starved estuaries.

Station scientists found that river networks, particularly small streams, can remove and retain some of this excess nitrogen, but their effectiveness is partly determined by surrounding land use. Across a range of land-use types (forest, agriculture, urban), the ability of small streams to process nitrate declined as ambient nitrate concentrations increased.

The results from these short-term studies are being combined with results from 40-year studies of nutrient export in the H.J. Andrews Experimental Forest. These findings provide guidelines for restoring and maintaining ecosystem functions.

Partners: Oregon State University, Lotic Intersite Nutrient Experiment

To learn more, contact Sherri Johnson at sherrijohnson@fs.fed.us.

Changes in stream temperatures are species-specific

Stream temperature is a major influence on aquatic insect emergence, affecting maturation rates, body size, and fecundity. In laboratory experiments, scientists examined the effects of three thermal regimes on emergence timing and adult body size of three species of common stream macroinvertebrates.

For one species in the warmest treatment, scientists observed a shift in timing of emergence of males by 23 days before the females from the same treatment and before individuals of either sex from the other temperatures. A second species showed no change in timing of emergence or size of adults when temperature was elevated, and a third species showed smaller size of adults at higher temperatures.

These findings suggest that subtle changes in thermal regimes, such as those associated with land management or climate change, may have effects on aquatic insect maturation and adult body size that are species-specific. These effects could have repercussions throughout the stream food web.

Partners: Oregon Department of Fish and Wildlife, Oregon Department of Forestry, Oregon State University, Watershed Research Cooperative, Weyerhaeuser Company

To learn more, contact Sherri Johnson at sherrijohnson@fs.fed.us.

Biomass in Oregon Coast Range is lower than in the past

Scientists examined the historical variation in live and dead tree biomass under the historical disturbance regime of the Oregon Coast Range. They found that current amounts of live and dead biomass are much lower than what occurred in this region before the high intensity wildfires of the early settlement period and intensive timber management of the 20th century.

This means these forests could probably sequester more carbon. This assessment provides the basis for understanding carbon management across a mixed-ownership landscape and is the first study to estimate the range of variation in terms of live and dead biomass.

Partners: Oregon State University, South Dakota State University

To learn more, contact Thomas A. Spies at tspies@fs.fed.us.

Peak flow assessment completed for BLM Plan Revisions

Station scientists assessed the science relating to the effects of forest management on peak streamflows in the Pacific Northwest (PNW). The Bureau of Land Management (BLM) used this assessment in their revised management plan for western Oregon. Scientists analyzed several decades of peak flow data from experimental watersheds across the PNW and developed novel relationships to guide forest managers in assessing the risk of peak flow increases and channel responses in different geographic regions within the PNW. The results of this effort were published in general technical report PNW-GTR-760.

Outcome: The Bureau of Land Management has used the assessment in its management plan for western Oregon.

Partner: USDI Bureau of Land Management

To learn more, contact Gordon Grant at ggrant@fs.fed.us.

Featured Publication-In the Blast Zone: Catastrophe and Renewal on Mount St. Helens

The Long-Term Ecological Reflections program brings together nature writers, poets, philosophers, and scientists to reflect on the natural world. One such gathering at Mount St. Helens led to the publication of In the Blast Zone: Catastrophe and Renewal on Mount St. Helens. This anthology of essays and poems addresses ecological, geological, and human dimensions of the 1980 eruption of the volcano. Writers offer their interpretations of the volcanic landscapes- the resilience of life, the changing character of a severely altered landscape, and the value of personal relationships in interdisciplinary inquiry in such a place. Writings from In the Blast Zone are now used in the interpretive program in the National Volcanic Monument, adding a humanities dimension to the interpretive program dominated by geology and ecology lessons.

To learn more, contact Fred Swanson at fswanson@fs.fed.us.

Partners: Oregon State University

More information: Goodrich, C.; Moore, K.D.; Swanson, F.J. 2008. In the Blast Zone: Catastrophe and Renewal on Mount St. Helens. Corvallis, OR: Oregon State University Press. 128 p.