Mortality, scarring, and growth in an oak woodland following prescribed fire and commercial thinning in the Ozark Highlands
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Forest Ecology and Management
Oak-dominated (Quercus Spp.) woodlands are commonly thinned and burned in the Ozark Highlands to prevent canopy closure and regenerate desired species, despite a lack of information regarding tree mortality, scarring, and growth in residual stands. Our study compared stand- and tree-level responses after two prescribed burns across four treatments: control, burn, thin, and thin + burn. Results showed that two prescribed fires led to 19% greater cumulative mortality than in unburned stands. In the burn treatment, 19.3% of residual live overstory trees were scarred, compared to 32.4% of trees in the thin + burn treatment. Analysis of scar area revealed that thinning before burning significantly increased the surface area (cm2) of fire scars. In general, trees in the red oak group (Erythrobalanus spp.) had the greatest percentage of scarred trees, followed by the white oak group (Leucobalanus spp.), hickories (Carya spp.), and shortleaf pines (Pinus echinata Mill.). Our data indicate that two fires did not significantly decrease the radial growth of white oaks, except in stands which were thinned prior to prescribed burns. Average percent change in ring-widths (mm) suggest a 1.9% growth decrease in control, 1.4% decrease in burn, 84% increase in thin, and a 35% increase in thin + burn. Covariates such as age, slope, surrounding basal area, canopy openness, and fire scars were analyzed, but tree diameter was the only significant predictor of growth response. Overall, results suggest that effects of prescribed burning are more pronounced in thinned stands as a function of increased fuel loads and fire intensity, causing greater mortality, fire scarring, and reductions in potential growth than fire or thinning alone. This study highlights important tradeoffs between prescribed fire and thinning in oak dominated ecosystems, especially where fire related damages are in potential conflict with other stand objectives.
Kinkead, C.S.; Stambaugh, M.C.; Kabrick, J.M. 2017. Mortality, scarring, and growth in an oak woodland following prescribed fire and commercial thinning in the Ozark Highlands. Forest Ecology and Management. 403: 12-26. https://doi.org/10.1016/j.foreco.2017.07.028.