Fourth Symposium on Fire and Forest Meteorology

Tuesday, 13 November 2001: 11:10 AM
Measuring Moisture Dynamics to Predict Fire Severity in Longleaf Pine Forests
Julia E. Ruthford, USDA Forest Service, Seattle, WA; and S. A. Ferguson
Poster PDF (375.0 kB)
To understand the combustion limit of biomass fuels in a longleaf pine [Pinus palustris] forest, an experiment was designed to monitor the moisture content of potentially flammable surface materials (litter, duff, and sand) at Eglin Air Force Base in the Florida. While longleaf pine forests are fire dependent ecosystems, a long history of fire suppression has allowed large amounts of pine litter, duff, and woody fuels to accumulate. Reintroducing fire to remove excess fuel without killing the longleaf pine trees requires care to burn under moisture conditions that alternately allow fire to carry while preventing root exposure or stem girdle. The study site was divided into 4 blocks that were burned under wet, moist, dry, and very dry moisture conditions. Throughout the 4-month experiment portable weather stations continuously collected meteorological data, which included continuous moisture measurements from in-situ, time-domain reflectometers. In addition, volumetric moisture samples were collected almost weekly and within an hour before each ignition and pre-burn fuel load and subsequent consumption was measured for each burn. Meteorological variables from the weather stations compared with moisture trends showed the influence of wind, temperature, relative humidity, and precipitation on the drying and wetting rates of the litter and duff. In addition, the magnitude and spatial variability of measured moisture showed significant influence on patterns of consumption and potential longleaf pine mortality.

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