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    Author(s): Y.S. Valachovic; C.A. Lee; H. Scanlon; J.M. Varner; R. Glebocki; B.D. Graham; D.M. Rizzo
    Date: 2011
    Source: Forest Ecology and Management 261(11): 1973-1986
    Publication Series: Scientific Journal (JRNL)
    PDF: Download Publication  (7.95 MB)


    We compared stand structure and fuel loading in northwestern California forests invaded by Phytophthora ramorum, the cause of sudden oak death, to assess whether the continued presence of this pathogen alters surface fuel loading and potential fire behavior in ways that may encumber future firefighting response. To attempt to account for these kinds of changes over a longer term than P. ramorum has been present in California, we supplemented sampling of pathogen-killed stands with those killed by herbicides. Although fuel loadings were greater in diseased than in undiseased stands, great variability was observed and the differences did not rise to the level of significance. Fuel loading observed in herbicide-treated stands was significantly greater than that in control stands (P < 0.001); total weight of downed woody debris (1-, 10-, 100-, and 1000-h fuel loadings) approximately doubled with the herbicide treatment ((image) ) over the control condition ((image) ). The increasing trends in herbicided and diseased plots resembled each other, suggesting that fuel loadings in diseased plots will continue to increase relative to the controls over a longer time horizon than observed. Fuel models based on the observed surface fuel accumulations in herbicide-treated and diseased plots predict that for some early-to-mid-phase (2–8 years) herbicide-treated forests, and for late-phase (8 years plus) diseased forests, rates of spread, flame lengths, and fireline intensities could increase significantly over the baseline, challenging effective firefighter response. These results, together with the “background” surface fuels observed in the control stands, highlight the need for fuels treatments and effective disease management strategies in infested stands and as sudden oak death expands throughout a broader region.


    • Surface fuels in sudden oak death (SOD)-affected stands increase over long time periods (8–12 years).
    • The increase in surface fuel loadings resembles that caused by herbicide treatments.
    • Herbicide-caused surface fuel increases are fast and transient, unlike SOD-caused increases.
    • SOD-caused increases in surface fuels may challenge future firefighter response in NW California.

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    Valachovic, Y.S.; Lee, C.A.; Scanlon, H.; Varner, J.M.; Glebocki, R.; Graham, B.D.; Rizzo, D.M. 2011. Sudden oak death-caused changes to surface fuel loading and potential fire behavior in Douglas-fir-tanoak forests. Forest Ecology and Management 261(11): 1973-1986


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    wildland fire, disease, fuel models, fire suppression, herbicide

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