Importance of biological processes in the sulfur budget of a northern hardwood ecosystem

Total S, organic S and sulfate were measured in foliage, litter, roots, soil and solutions at a hardwood site within the Adirondack Mountains of New York. Sulfate as a percentage of total S was similar in foliage and litter (10%), but was greater in roots (30%). Sulfur constituents in the hardwood forest ecosystem were dominated by C-bonded S (60 g m^-2) and ester sulfate (16 g m^-2) which are formed by biological processes. Because sulfur mineralization (1.42 g m^-2 yr^-1) was greater than wet precipitation inputs (0.82 g m^-2 yr^-1), those factors that influence mineralization-immobilization processes are important in evaluating S cycling and sulfate fluxes in this ecosystem. Ester sulfate was formed within the forest floor by the soil biota and was leached to mineral horizons. Annual turnover of this pool was high (25%) within the mineral forest floor. Forest-floor C-bonded S was derived from root and above-ground litter, and substantial amounts were leached to mineral horizons. Calculated storage + outputs (1.64 g m^-2 yr^-1) was much greater than wet inputs (0.82 g m^-2 yr^-1).