Increasing elevation of fire in the Sierra Nevada and implications for forest change
Authors:Schwartz, Mark W.Butt, NathalieDolanc, Christopher R.Holguin, AndrewMoritz, Max A.North, Malcolm P.Safford, Hugh D.Stephenson, Nathan L.Thorne, James H.van Mantgem, Phillip J.
Source:ECOSPHERE
Volume:6
Published:2015
Document Type:Article
Abstract:Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we find that the upper elevation extent of those fires has also been increasing. Factors such as fire season climate and fuel build up are recognized potential drivers of changes in fire regimes. Patterns of warming climate and increasing stand density are consistent with both the direction and magnitude of increasing elevation of wildfire. Reduction in high elevation wildfire suppression and increasing ignition frequencies may also contribute to the observed pattern. Historical biases in fire reporting are recognized, but not likely to explain the observed patterns. The four plausible mechanistic hypotheses (changes in fire management, climate, fuels, ignitions) are not mutually exclusive, and likely have synergistic interactions that may explain the observed changes. Irrespective of mechanism, the observed pattern of increasing occurrence of fire in these subalpine forests may have significant impacts on their resilience to changing climatic conditions.
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Reprint Address:Schwartz, MW (corresponding author), Univ Calif Davis, Dept Environm Sci & Policy, Davis, CA 95616 USA.
Addresses:[Schwartz, Mark W.; Dolanc, Christopher R.; Holguin, Andrew; Safford, Hugh D.; Thorne, James H.] Univ Calif Davis, Dept Environm Sci & Policy, Davis, CA 95616 USA. [Schwartz, Mark W.] Univ Calif Davis, John Muir Inst Environm, Davis, CA 95616 USA. [Butt, Nathalie] Univ Queensland, Sch Biol Sci, St Lucia, Qld 4072, Australia. [Dolanc, Christopher R.] Mercyhurst Univ, Dept Biol, Erie, PA 16546 USA. [Moritz, Max A.] Univ Calif Berkeley, Dept Environm Sci Policy & Management, Berkeley, CA 94720 USA. [North, Malcolm P.] US Forest Serv, Pacific Southwest Res Stn, Davis, CA 95618 USA. [Safford, Hugh D.] US Forest Serv, USDA, Pacific Southwest Reg, Vallejo, CA 94592 USA. [Stephenson, Nathan L.] US Geol Survey, Western Ecol Res Ctr, Three Rivers, CA 93271 USA. [van Mantgem, Phillip J.] US Geol Survey, Western Ecol Res Ctr, Redwood Field Stn, Arcata, CA 95521 USA.
E-mail Addresses:mwschwartz@ucdavis.edu