title: Response of Sierra Nevada forests to projected climate-wildfire interactions.
abstract: Climate influences forests directly and indirectly through disturbance. The interaction of climate change and increasing area burned has the potential to alter forest composition and community assembly. However, the overall forest response is likely to be influenced by species-specific responses to environmental change and the scale of change in overstory species cover. In this study, we sought to quantify how projected changes in climate and large wildfire size would alter forest communities and carbon (C) dynamics, irrespective of competition from nontree species and potential changes in other fire regimes, across the Sierra Nevada, USA. We used a species-specific, spatially explicit forest landscape model (LANDIS-II) to evaluate forest response to climate-wildfire interactions under historical (baseline) climate and climate projections from three climate models (GFDL, CCSM3, and CNRM) forced by a medium-high emission scenario (A2) in combination with corresponding climate-specific large wildfire projections. By late century, we found modest changes in the spatial distribution of dominant species by biomass relative to baseline, but extensive changes in recruitment distribution. Although forest recruitment declined across much of the Sierra, we found that projected climate and wildfire favored the recruitment of more drought-tolerant species over less drought-tolerant species relative to baseline, and this change was greatest at mid-elevations. We also found that projected climate and wildfire decreased tree species richness across a large proportion of the study area and transitioned more area to a C source, which reduced landscape-level C sequestration potential. Our study, although a conservative estimate, suggests that by late century, forest community distributions may not change as intact units as predicted by biome-based modeling, but are likely to trend toward simplified community composition as communities gradually disaggregate and the least tolerant species are no longer able to establish. The potential exists for substantial community composition change and forest simplification beyond this century.
authors: Intercollege Graduate Degree Program in Ecology and Department of Ecosystem Science and Management, The Pennsylvania State University, 228 Forest Resources Building, University Park, PA, 16802, USA.
authors: Shuang
authors: S
authors: Liang
authors: Department of Biology, University of New Mexico, MSC03 2020, Albuquerque, NM, 87131, USA.
authors: Matthew D
authors: 0000-0001-8457-8974
authors: MD
authors: Hurteau
authors: Sierra Nevada Research Institute, University of California, 5200 N. Lake Road, Merced, CA, 95343, USA.
authors: Anthony LeRoy
authors: AL
authors: Westerling
mesh_terms: D002980:Climate; D057231:Climate Change; D005390:Fires; D065928:Forests; D009505:Nevada; D014197:Trees
keywords: LANDIS-II; Sierra Nevada; carbon; climate change; forest community change; wildfire