Sulfur, carbon, and nitrogen relationships in forest soils across the northern Great Lakes States as affected by atmospheric deposition and vegetation

The 169 forested plots across Minnesota, Wisconsin and Michigan were geographically stratified into 5 zones, with wet sulfate deposition increasing from 156 (zone 1) to 380 (zone 5) equiv..ha^-1.yr^-1. Total S concentrations, adjusted for N levels, indicated higher concentrations in E than in W zones in both the upper mineral soil (c. 0.0152 and 0.0133% S, respectively) and forest floor (c. 0.124 and 0.113% S, respectively), ie forest soil S levels reflect geographic gradients in atmospheric sulfate deposition. Total C and N concentrations and C:N and C:S ratios were affected by vegetation type. Jack pine Pinus banksiana and red pine P. resinosa mineral soil had lower concentrations of C and N compared with balsam fir Abies balsamea, maple Acer spp and aspen Populus tremuloides. Forest floor C and N showed no clear pattern. -Authors