Long-term effects of commercial sawlog harvest on soil cation concentrations

There is increasing concern about the effects of nutrient removal associated with various forest harvesting practices on long-term site productivity. We measured exchangeable soil cation concentration responses to a commercial clearcut sawlog harvest in mixed hardwoods on a 59-ha watershed in the southern Appalachians. Soils were sampled 17 months prior to, and periodically for 17 years after, harvest. Concentrations of Ca, Mg, and K, increased significantly in the 0-10-cm soil layer for 3 years following harvest compared to pre-treatment levels. Concentrations of Mg and K were still significantly above pre-treatment levels 17-20 years following harvest. Calcium concentrations did not change significantly at the 10-30 cm depth, but both Mg and K showed significantly higher concentrations in some post-treatment years. Soils in the adjacent reference watershed showed no significant changes in soil cation concentrations over the same 17-year period. Results indicate that sawlog harvest using cable-yarding techniques on these sites does not adversely impact soil cation concentrations. (C) 1997 Elsevier Science B.V.