Site preparation burning to improve southern Appalachian pine–hardwood stands: aboveground biomass, forest floor mass, and nitrogen and carbon pools

Abstract

On three sites in the southern Appalachians, stands characterized by sparse overstories and dense Kalmialatifolia L. shrub layers were felled in early summer and burned in early fall. Amounts of aboveground vegetation and forest floor mass, nitrogen (N), and carbon (C) were measured before and after treatment by sampling wood, foliage, herbs, grasses, and forest floor (Oi and Oe + Oa layers). Burning decreased woody mass by 48 to 60% across the three sites. The most intense burn reduced mass from 180 to 70 Mg•ha−1, and N and C losses were 300 kg•ha−1 and 52 Mg•ha−1, respectively. Significant losses of mass, N, and C occurred in the Oi layer, but not in the Oe + Oa layer. Foliage, herbs, and grasses were totally consumed by the fires. Total aboveground N losses across sites ranged from 193 to 480 kg•ha−1. These losses may be significant because N availability is low on these sites. Variations in patterns of mass, N, and C consumption were related to differences in amounts, types, size distributions, and moisture contents of fuels.