The Wind River alder strip revisited: Lessons for post-fire management on recent and future western Washington and Oregon fires

Abstract

A forester set up a large-scale, 1600-m fire-break trial with red alder (Alnus rubra Bong.) inter-planted between Douglas-fir (Pseudotsuga menziesii Mirb Franco), after the extensive 1927 Yacolt Burn in the Columbia Gorge. This now 90-year-old trial demonstrates dramatic effects of alder on soils and growth of Douglas-fir; it also provides a timely lesson for foresters deciding what to do after recent similar fires in western Oregon and Washington. We used 2015 airborne lidar to re-examine the trial effects. Douglas-fir trees in stands mixed with alder (Strip) continue to grow taller than those in adjacent pure stands (Controls), even though almost all alder died out 30–40 years ago. Site index in Strip stand continues to increase relative to Controls, now averaging 30–40 % higher than Controls. Basal area ha−1 is 2.1, and stem biomass is 2.8 times higher in Strip than Control stands. Implications and future studies are discussed. Before planting wall-to-wall Douglas-fir, foresters responding to new fires in this region might contemplate alder interplanting and crop rotation for their likely positive effect on future revenue, wildlife, and carbon sequestration rates and storage above and belowground.