Managed Wildfire Effects on Forest Resilience and Water in the Sierra Nevada
- 1.3k Downloads
Fire suppression in many dry forest types has left a legacy of dense, homogeneous forests. Such landscapes have high water demands and fuel loads, and when burned can result in catastrophically large fires. These characteristics are undesirable in the face of projected warming and drying in the western US. Alternative forest and fire treatments based on managed wildfire—a regime in which fires are allowed to burn naturally and only suppressed under defined management conditions—offer a potential strategy to ameliorate the effects of fire suppression. Understanding the long-term effects of this strategy on vegetation, water, and forest resilience is increasingly important as the use of managed wildfire becomes more widely accepted. The Illilouette Creek Basin in Yosemite National Park has experienced 40 years of managed wildfire, reducing forest cover by 22%, and increasing meadow areas by 200% and shrublands by 24%. Statistical upscaling of 3300 soil moisture observations made since 2013 suggests that large increases in wetness occurred in sites where fire caused transitions from forests to dense meadows. The runoff ratio (ratio of annual runoff to precipitation) from the basin appears to be increasing or stable since 1973, compared to declines in runoff ratio for nearby, unburned watersheds. Managed wildfire appears to increase landscape heterogeneity, and likely improves resilience to disturbances, such as fire and drought, although more detailed analysis of fire effects on basin-scale hydrology is needed.
Keywordsforest structure montane hydrology mixed conifer meadow wildfire resilience soil moisture fire ecology wildland fire use
The authors specially thank Kate Wilkin for her field expertise, and all of this project’s field crew members and volunteers: Miguel Naranjo, Andy Wong, Perth Silvers, Jeremy Balch, Seth Bergeson, Amanda Atkinson, Tom Bruton, Diane Taylor, Madeleine Jensen, Isabel Schroeter, Katy Abbott, Bryce King, Zubair Dar, Katherine Eve, Sally McConchie, Karen Klonsky, and Yves Boisramé. The vegetation maps were created by GIS technicians Julia Cavalli, Miguel Naranjo, and Melissa Ferriter, with guidance from Professor Maggi Kelly. We thank Jan van Wagtendonk and John Battles for discussions related to this project. Thanks to financial support from Joint Fire Science Grant # 14-1-06-22, Sigma Xi Grants in Aid of Research, the UC Berkeley SMART program, Hellman Fellows Program, and the UC Berkeley Philomathia Graduate Fellowship in Environmental Sciences. The authors thank Yosemite National Park for permitting us to conduct research in wilderness areas.
- Allen CD, Macalady AK, Chenchouni H, Bachelet D, McDowell N, Vennetier M, Kitzberger T, Rigling A, Breshears DD, Hogg ET et al. 2010. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest ecology and management 259(4):660–84.CrossRefGoogle Scholar
- Californian Department of Water Resources (2008) Managing an uncertain future: Climate change adaptation strategies for California’s water. Technical report Californian Department of Water Resources.Google Scholar
- Campbell Scientific (2015) HS2. http://www.campbellsci.com/hs2.
- Coleman, TW, Heath, Z, Cluck, D, Flowers, R, Hanavan, R, Graves, G. 2015. Multiregional accuracy assessment of aerial detection survey data. Technical report USDA Forest Service, Forest Health and Protection, available from http://foresthealth.fs.usda.gov/portal.
- Collins, B, Skinner, C. 2014. Fire and Fuels in Science synthesis to promote resilience of social- economic systems in the Sierra Nevada and southern Cascade range. General Technical Report PSW-GTR-247. Technical report United States Forest Service.Google Scholar
- Dettinger, MD, Anderson, ML. 2015. Storage in California’s reservoirs and snowpack in this time of drought. San Francisco Estuary and Watershed Science 13(2).Google Scholar
- Goulden, M, Anderson, R, Bales, R, Kelly, A, Meadows, M, Winston, G. 2012. Evapotranspiration along an elevation gradient in California’s Sierra Nevada. Journal of Geophysical Research: Biogeosciences 117(G3).Google Scholar
- Gunderson, LH. 2000. Ecological resilience–in theory and application. Annual Review of Ecology and Systematics 425–439.Google Scholar
- LANDFIRE. 2012a. Biophysical setting layer, LANDFIRE 1.3.0. LANDFIRE. 2012b. Existing vegetation type layer, LANDFIRE 1.3.0.Google Scholar
- Liaw, A, Wiener, M. 2015. Breiman and Cutler’s random forests for classification and regression. R Package RandomForest.Google Scholar
- McGarigal, K, Cushman, S, Ene, E. 2012. FRAGSTATS v4: Spatial pattern analysis program for categorical and continuous maps. computer software program produced by the authors at the University of Massachusetts, amherst. http://www.umass.edu/landeco/research/fragstats/fragstats.html.
- Milledge DG, Warburton J, Lane SN, Stevens CJ. 2013. Testing the influence of topography and material properties on catchment-scale soil moisture patterns using remotely sensed vegetation patterns in a humid temperate catchment, northern Britain. Hydrological Processes 27(8):1223–37.CrossRefGoogle Scholar
- Moore J. 2015. Aerial detection survey - April 15th-17th, 2015. Forest Service: Technical report United States Department of Agriculture.Google Scholar
- Neary D, Ryan KC, DeBano LF. 2005. Wildland fire in ecosystems: Effects of fire on soil and water. Forest Service: Technical report United States Department of Agriculture.Google Scholar
- Oregon State University. 2004. PRISM Climate Group. http://prism.oregonstate.edu.
- Royce, EB, Barbour, MG. 2001. Mediterranean climate effects. i. conifer water use across a Sierra Nevada ecotone. American Journal of Botany 88(5): 911–918.Google Scholar
- Soulard, CE. 2015. Sierra Nevada ecoregion summary. http://landcovertrends.usgs.gov/west/eco5Report.html.
- Stephens SL, Moghaddas JJ, Edminster C, Fiedler CE, Haase S, Harrington M, Keeley JE, Knapp EE, McIver JD, Metlen K et al. 2009. Fire treatment effects on vegetation structure, fuels, and potential fire severity in western US forests. Ecological Applications 19(2):305–20.CrossRefPubMedGoogle Scholar
- Thode, A. 2005. Quantifying the fire regime attributes of severity and spatial complexity using field and imagery data. PhD thesis Davis, CA: University of California.Google Scholar
- University of Montana. 2015. Wilderness.net. http://www.wilderness.net/index.cfm?fuse=NWPS&sec=geography.
- USDA Farm Service Agency. 2015. NAIP imagery. http://www.fsa.usda.gov/programs-and- services/aerial-photography/imagery-programs/naip-imagery/index.
- USDA-FS. 2011. Region five ecological restoration: Leadership intent. March 2011. U.S. Forest Service, Pacific Southwest Region.Google Scholar
- USGS. 2015. The national map: 3D elevation program (3DEP) http://nationalmap.gov/3DEP/index.html.
- van Wagtendonk, JW. 2007. The history and evolution of wildland fire use. Fire Ecology 3: 3–17. Weiss, A. 2001. Topographic position and landforms analysis. In Poster presentation, ESRI User Conference, San Diego, CA pages 200–200.Google Scholar