To understand the activities of the salmon, researchers applied topographically derived stream-layering techniques and a formula created by Burnett in 2007 for estimating the "intrinsic potential" of each stream to provide rearing habitats for Coho salmon.
They found that valleys downstream of landslides are narrower than would be expected, which suggested that valley constriction had subverted valley widening. Deep-seated landslides, the authors noted, caused wide valley segments to occur higher in the channel network than would otherwise be expected. Off-channel streams perched in mountain drainages, they said, increase habitat diversity and lead to a greater abundance of salmonid productivity.
"This study establishes how a valley sets its width," Roering said. "More importantly, the anomalies that make valleys look different are primarily controlled by big landslides in the Oregon Coast Range. Big events occurring thousands of years ago have had a long-running, persistent impact on the valley floor. So even if landslides sound scary or deadly, they've been active out there for long periods of time, and they make great habitat for salmon over the long term."
The findings provide fundamental insights on the geological and ecological controls on salmon habitat, May said. "I do believe the results will have broad applications for endangered species conservation and management," she added.
"Dr. Roering's explanation of how destructive natural forces can create fertile habitat answers some long-lingering questions about the geomorphology of our region," said Kimberly Andrews Espy, UO vice president for research and innovation, and dean of the graduate school. "This research helps us appreciate the richness and diversity of our state by furthering our understanding o
|Contact: Jim Barlow|
University of Oregon