Effects of Nitrogen Enrichment, Wildfire, and Harvesting on Forest-Soil Carbon and Nitrogen

Abstract

Northern forest soils represent large reservoirs of C and N that may be altered by ecosystem perturbations. Soils at three paired watershed in Maine were investigated as case studies of experimentally elevated N deposition, wildfire, and whole-tree harvesting. Eight years of experimental (NH₄)₂SO₄ additions at the Bear Brook Watershed in Maine significantly reduced forest-floor C/N ratios from 30.6 to 23.4. Forest-floor C and N pools were lower in the treated watershed (38 Mg C ha^-1, 1612 kg N ha^-1) compared with the reference (75 Mg C ha^-1, 2372 kg N ha^-1). Fifty years after wildfire at Acadia National Park, the burned watershed with hardwood regeneration had significantly lower forest-floor C and N concentrations (208 g C kg^-1 soil, 9.9 g N kg^-1 soil) than the reference watershed dominated by a softwoods (437 g C kg^-1 soil, 12.8 g N kg^-1 soil). Forest-floor C and N pools were lower in the burned watershed (27 Mg C ha^-1, 1323 kg N ha^-1) compared with the reference (71 Mg C ha^-1, 2088 kg N ha^-1). At the Weymouth Point, the harvested watershed regenerated to spruce-fir, the dominant stand type that existed before the harvest, and it had significantly lower forest-floor C concentrations and pools (406 g C kg^-1 soil, 24 Mg C ha^-1) than the reference (442 g C kg^-1 soil, 39 Mg C ha^-1) after 17 yr. All perturbations studied were associ- ated with lower forest-floor C pools.

Citation

Parker, Jennifer L.; Fernandez, Ivan J.; Rustad, Lindsey E.; Norton, Stephen A. 2001. Effects of Nitrogen Enrichment, Wildfire, and Harvesting on Forest-Soil Carbon and Nitrogen. Soil Science Society of America Journal. 65(4): 1248-1255. https://doi.org/10.2136/sssaj2001.6541248x.