Changes in Carbon and Nutrient Contents in Vegetation, Forest Floor, and Soils in a Mixed Oak Forest 33 Years after Stem Only and Whole-Tree Harvest.

Vegetation, forest floor, and soils were resampled at a mixed oak site in eastern Tennessee that had been subjected to stem only (SOH), whole-tree harvest (WTH), and no harvest (REF) 33 years previously. Soil total C and total N contents increased in both harvest treatments over the first 15 years. Soil and total ecosystem N contents increased during this time by amounts that could not be explained by atmospheric deposition or N fixation. Between years 15 and 30, soil C and N contents decreased in the WTH treatment but not in the SOH treatment. Soil extractable P decreased continuously over time in both harvest treatments. Only part of these decreases could be accounted for by increases in vegetation and detritus. Soil exchangeable and total ecosystem K contents fluctuated over time but none of the soil changes were statistically significant. Soil exchangeable Ca2+ and, to a lesser extent, Mg2+ contents changed considerably over time, reflecting inputs from decomposing logging residues and increments in vegetation and detritus. Vegetation biomass and nutrient contents did not differ between harvest treatments over the first 15 years, but were lower in the WTH treatment at 33 years. Forest floor biomass and nutrient contents did not differ between harvest treatments over the first 15 years, but were greater in the WTH treatment at 33 years. Further monitoring and research is needed to determine the cause(s) of the observed changes in vegetation and forest floor.