Year Published: 2017
Description: Interest in PNW forests is shifting from a focus on old-growth forests alone to include the ecological value and processes of early-seral communities. However, focusing on the alpha and omega states of a linear successional model does not account for the suite of conditions derived from mixed-severity fire common in many forests. There has also been a continued interest in salvage logging as fire extent continues to increase in these forests. Therefore, examining the effects of mixed-severity fire and salvage logging on forest structure, the generator of early-seral and other vegetation communities, and tree regeneration communities has become critical. To do so, we sampled forest structure (1000 m2 circular plots), understory vegetation (100 m2 plots) and tree regeneration (100 m2 plots) at 216 co-located plots stratified across unburned, low, moderate, high-severity and salvaged logged conditions 10 and 22-years post-fire on the west slope of Oregon’s Cascade Mountains. We quantified the probability of mortality by tree species and cumulative effects of individual tree mortality on forest structure across the fire severity gradient and following salvage logging. We then investigated understory vegetation response to these post-fire and management conditions, as well as variability in tree regeneration. Our results presented in this report suggest mixed-severity fire is functionally important to Pseudotsuga forests of the PNW as it increases structural and compositional diversity in both the near and long-term. Despite increasing fire extent across much of the western U.S. and concerns regarding the resilience of many forests, our study highlights the benefits contemporary fires have on many ecological processes and supports the expansion of beneficial fire across these landscapes as society shifts towards learning to live with fire.