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Frequent Prescribed Burning as a Long-term Practice in Longleaf Pine Forests Does Not Affect Detrital Chemical Composition

Coates, T. Adam, Chow, Alex T., Hagan, Donald L., Wang, G. Geoff, Bridges, William C., Dozier, James H.
Journal of environmental quality 2017 v.46 no.5 pp. 1020-1027
Pinus palustris, benzene, chemical composition, coniferous forests, detritus, ecosystems, forest soils, fuels, fuels (fire ecology), gas chromatography-mass spectrometry, organic horizons, phenol, polycyclic aromatic hydrocarbons, prescribed burning, pyrolysis gas chromatography, stakeholders, wildlife, South Carolina
The O horizon, or detrital layer, of forest soils is linked to long-term forest productivity and health. Fuel reduction techniques, such as prescribed fire, can alter the thickness and composition of this essential ecosystem component. Developing an understanding of the changes in the chemical composition of forest detritus due to prescribed fire is essential for forest managers and stakeholders seeking sustainable, resilient, and productive ecosystems. In this study, we evaluated fuel quantity, fuel structure, and detrital chemical composition in longleaf pine (Pinus palustris Miller) forests that have been frequently burned for the last 40 yr at the Tom Yawkey Wildlife Center in Georgetown, SC. Our results suggest that frequent prescribed fire reduces forest fuel quantity (p < 0.01) and vertical structure (p = 0.01). Using pyrolysis–gas chromatography/mass spectrometry as a molecular technique to analyze detrital chemical composition, including aromatic compounds and polycyclic aromatic hydrocarbons, we found that the chemical composition of forest detritus was nearly uniform for both unburned and burned detritus. Our burning activities varied in the short term, consisting of annual dormant, annual growing, and biennial dormant season burns. Seasonal distinctions were present for fuel quantity and vertical fuel structure, but these differences were not noted for the benzene/phenol ratio. These results are significant as more managers consider burning existing longleaf stands while determining effective management practices for longleaf stands yet to be established. Managers of such stands can be confident that frequent, low-intensity, low-severity prescribed burns in longleaf pine forests do little to affect the long-term chemical composition of forest detritus.