Cycling of organic and inorganic sulphur in a chestnut oak forest

Sulfur (S) cycling in a chestnut oak forest on Walker Branch Watershed, Tennessee, was dominated by geochemical processes involving sulfate. Even though available SO₄^2-was present far in excess of forest nutritional requirements, the ecosystem as a whole accumulated ~60% of incoming SO₄-S. Most (90%) of this accumulation occurred by SO₄^2-adsorption in sesquioxide-rich subsurface soils, with a relatively minor amount accumulating and cycling as SO₄^2-within vegetative components. Organic sulfates are thought to constitute a large proportion of total S in surface soils, also, and to provide a pool of readily mineralized available S within the ecosystem.