This project was funded by the Joint Fire Science Program under Project JFSP 14‐1‐01‐2. Additional funds were provided by Microsoft Azure for Research and Portland State University's Ed and Olive Bushby Scholarship Fund. This work was also supported by the U.S. Department of Agriculture Forest Service National Fire Plan. We acknowledge the U.S. Department of Agriculture Forest Service, Southern Research Station, and the Center for Forest Disturbance Science, Athens, Georgia, for their support. We thank Andres Holz, Jeffrey Gerwing, and Max Nielsen‐Pincus for valuable input and members of the Blue Mountain Forest Partnership and the Harney Country Restoration Collaborative as well as the Blue Mountain Ranger District of the USDA Forest Service, Oregon Department of Forestry, and the Bureau of Land Management for data and consultation. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Appendix S1: Table S6) for producing and making available their model output. We also thank two anonymous reviewers whose comments substantially improved this manuscript. The authors declare no conflicts of interest.
Forests -- Climatic factors, Climatic changes
Climate warming in the western United States is causing changes to the wildfire regime in mixed-conifer forests. Rising temperatures, longer fire seasons, increased drought, as well as fire suppression and changes in land use, have led to greater and more severe wildfire activity, all contributing to altered forest composition over the past century. To understand future interactions among climate, wildfire, and vegetation in a fire-prone landscape in the southern Blue Mountains of central Oregon, we used a spatially explicit forest landscape model, LANDIS-II, to simulate forest and fire dynamics under current management practices and two projected climate scenarios. The results suggest that wildfires will become more frequent, more extensive, and more severe under projected climate than contemporary climate. Furthermore, projected climate change generated a 20% increase in the number of extreme fire years (years with at least 40,000 ha burned). This caused large shifts in tree species composition, characterized by a decline in the sub-alpine species (Abies lasiocarpa, Picea engelmannii, Pinus albicaulis) and increases in lowerelevation species (Pinus ponderosa, Abies grandis), resulting in forest homogenization across the elevational gradient. This modeling study suggests that climate-driven increases in fire activity and severity will make high-elevation species vulnerable to decline and will reduce landscape heterogeneity. These results underscore the need for forest managers to actively consider climate change, altered fire regimes, and projected declines in sub-alpine species in their long-term management plans.
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Cassell, B. A., Scheller, R. M., Lucash, M. S., Hurteau, M. D., & Loudermilk, E. L. (2019). Widespread severe wildfires under climate change lead to increased forest homogeneity in dry mixed‐conifer forests. Ecosphere, 10(11), e02934.