Fuels consumption and nitrogen loss following prescribed fire: a comparison of prescription types in the Southern appalachiansThis article is part of a larger document. View the larger document here.
Prescribed burning is frequently used as a tool for restoration of plant communities, wildlife habitat improvement, and site preparation. We compared and contrasted the effects of four burning prescriptions on forest floor and fine fuels consumption, and nitrogen loss. The burning treatments included dry (DU) and mesic (MU) understory burns, stand replacement (SR) burning, and fell and burn (FB) site preparation. On all sites, forest floor was sampled before and immediately after burning. It was separated into woody fuels (< 7.5 cm in diameter), the Oi layer (litter), and the Oa + Oe layer (fermentation plus humus), and dry weight and nitrogen content of each component was determined. Tiles with heat-sensitive chalk and paint were used to estimate flame intensity at 30 cm above the forest floor. Mean peak flame temperatures ranged from 700 ºC for the FB treatment to 169 ºC for the MU burn. Except in the FB treatment, which had a substantial amount of woody mass on the forest floor as a result of felling overstory trees and shrubs, the majority of pre-burn mass and nitrogen was contained in the humus layer. Following burning, mass loss ranged from 88 Mg ha-1 (90 percent wood, 10 percent litter, < 5 percent humus) on the FB treatment to 5 Mg ha-1 (5 percent wood, 55 percent litter, 40 percent humus) on the MU burns. Nitrogen losses followed similar patterns – 292 kg ha-1 (70 percent from wood, 28 percent litter, < 5 percent humus) on the FB to 30 kg ha-1 (65 percent from wood, 35 percent litter, < 5 percent humus) on the SR site. High-intensity ground fires may result in greater losses of site nutrients, and this may have negative short- and long-term consequences.