Aboveground biomass and nutrient accumulation 20 years after clear-cutting a southern Appalachian watershed

Abstract

In 1975, we initiated a long-term interdisciplinary study of forest watershed ecosystem response to clear-cutting and cable logging in watershed 7 at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of North Carolina. This paper describes [Formula: see text]20 years of change in species composition, aboveground biomass, leaf area index (LAI), and nutrient pools in the 59-ha mixed hardwood forest of watershed 7 following commercial clear-cutting in winter 1977. We measured woody species in 24 permanently marked plots before cutting in 1974 and during subsequent years (1977–1997). By 1997 ([Formula: see text]20 years after cutting), aboveground biomass was 81.7, 96.9, and 85.4 Mg·ha–1in the cove hardwood; mesic, mixed-oak; and dry, mixed-oak communities, respectively. Leaf biomass and LAI accumulated relatively faster than total aboveground biomass in all three communities. By 1984, only 7–8 years after cutting, leaf biomass and LAI were nearly equal to the amount estimated for the precut forest. In 1997, nitrogen accumulation was 36, 44, and 61% and phosphorus accumulation was 48, 66, and 59% in the cove-hardwoods; mesic, mixed-oak; and dry, mixed-oak communities of the corresponding precut communities, respectively. Potassium, calcium, and magnesium accumulations were less than either nitrogen or phosphorus accumulation.