After devastating wildfires, watersheds surprisingly thick with fish and amphibians In the aftermath of Oregon’s historically severe wildfires in 2020, a study of Cascade Range watersheds found that stream vertebrates are doing surprisingly well, highlighted by flourishing fish populations. Led by Oregon State University postdoctoral researcher Allison Swartz, the research examined 30 watersheds in moist conifer forests on the western slope of the Cascades over three years following the Riverside, Beachie Creek and Holiday Farm megafires. Unlike many previous studies that focused mainly on salmon and trout, this research emphasized larger streams hosting non-salmonid fishes such as dace, sculpin and lamprey, as well as salamanders, frogs and crayfish. The watersheds, spanning federal, state and private lands, experienced varying burn severity and post-fire management, including salvage logging and replanting. “Understanding the fire ecology of freshwater ecosystems is critical to our learning to coexist with fire in ways that are socially and ecologically just,” said co-author Meg Krawchuk, an associate professor in the OSU College of Forestry. Researchers found that overall vertebrate, fish and trout densities were higher in streams draining more severely burned watersheds compared to less burned or unburned areas. While sculpin, amphibian and crayfish densities were largely unaffected by burn severity, areas with more intensive salvage RESEARCH UPDATES logging showed lower frog densities and higher numbers of young trout. The findings highlight the importance of maintaining physical habitat and food availability after fire and contribute to understanding how freshwater ecosystems can coexist with increasingly frequent and intense wildfires. Collaborators included Oregon State University, the National Council for Stream Improvement, Inc., the U.S. Forest Service’s Pacific Northwest Research Station and the U.S. Environmental Protection Agency. Read more: beav.es/SjL Wildfire risk making timberland less valuable and long harvest rotations less feasible Rising wildfire risk in the Pacific Northwest, combined with volatile timber prices, could reduce forestland values by as much as 50% and push plantation owners to harvest Douglas-fir trees decades earlier than planned, according to new Oregon State University research. Associate Professor Mindy Crandall, Assistant Professor Andres Susaeta, and doctoral student Hsu Kyaw modeled how increasing fire risk influences forest management decisions. Their analysis shows that under worst-case wildfire scenarios, harvesting at 24 years becomes economically optimal, compared with 65 years in the absence of fire risk. “Basically, under high wildfire risk that rises with stand age, every year you wait to harvest you’re rolling the dice,” said Crandall. However, earlier harvesting reduces long-term revenue, carbon storage and wood quality. 12 COLLEGE OF FORESTRY
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