Using stand replacement fires to restore southern Appalachian pine–hardwood ecosystems: effects on mass, carbon, and nutrient pools

Abstract

Pine–hardwood ecosystems in the southern Appalachians are in serious decline due to fire exclusion and insect infestations. Fire has been advanced as a tool to restore these ecosystems, yet there are few studies evaluating overall ecosystem effects. Our objectives were to evaluate the effects of stand restoration burning on forest floor nitrogen (N) and carbon (C) pools, and soil and stream chemistry. We measured changes in forest floor (coarse woody debris, small wood, litter, and humus) mass, N, and C; changes in soil chemistry (calcium (Ca), potassium (K), magnesium (Mg), cation exchange capacity (CEC), pH, C, and N); and changes in stream nitrate (NO 3). Results showed that significant reductions in mass, N, and C occurred only for litter and small wood on the ridge, where N losses were 52.9 kg ha −1 for litter and small wood combined. No significant effects were observed on the mid- or lower slope of the treatment watershed. Losses on the ridge are considerably lower than losses which occur with alternative burning treatments used in the region, such as the fell and burn treatment. Soil and stream chemistry showed no response to burning. Spatial heterogeneity in fire intensity (combustion temperatures ranged from <52–>800°C) and severity associated with stand replacement burning results in a mosaic of fire effects and considerably less consumption and subsequent nutrient losses.