Soil pH and divalent cations after clear-cutting on a Japanese cypress plantation

Although Chamaecyparis obtusa reduces soil pH and cation levels, limited information is available regarding their alterations after clear-cutting. We examined the soil pH and base cations on the upslopes and downslopes of individual trees and stumps of C. obtusa at two distances (0.5 m and 1.0 m) and three depths (0-5, 5-10, and 10-30 cm) in intact- and cut-tree plots. The soil pH was higher in the cut-tree plot than in the intact-tree plot, indicating the recovery of soil pH after clear-cutting. The recovery was more evident in the surface soils (0-5 cm) of downslope areas (0.5 m) than in other soil depths, which implies that the recovery of soil pH was caused by the lack of H+ supply from stumps after clear-cutting. The results of H+ (in H2O: water-soluble and KCl: exchangeable) suggested a lack of soluble H+ in the cut-tree plot. Soil Ca2+ and Mg2+ levels in the surface soil (0-5 cm) were 1.86-fold and 1.93-fold higher in the cut-tree plot than in the intact-tree plot, respectively, implying that the recovery of divalent cations after clear-cutting was caused by a reduction in cation loss through cation exchange with H+ derived from the stemflow. Collectively, soil pH and divalent cations were recovered after clear-cutting because the stemflow had ceased.