Abstract
The promotion of over-utilization of forest biomass, especially the removal of logging residues, including the nutrient-rich foliage, at whole-tree harvesting, might influence the nutrient status of forest soils and sustainability of site productivity. To determine the short-term impact of logging residues on forest soils, we conducted thinning with and without logging residue removal (whole-tree harvesting (WTH) and stem-only harvesting (SOH), respectively). Subsequently, we investigated the changes in the dynamics of cations (Ca, Mg, and K) in the soils by using an ion-exchange resin at the WTH and SOH plots of Japanese cedar (Cryptomeria japonica) forests in northern Japan. We observed rapid decomposition of logging residues in the O horizon in SOH plot. Further, we found that K ions moved from the O horizon to the surface soil at the early stage of decomposition in the SOH plot, whereas a minor difference in the movement of Ca and Mg ions was noted at the 0- and 50-cm soil depths between the plots. Furthermore, there was no significant difference in the amounts of exchangeable cations at the surface soil (0―5-cm depth) between both the plots. Therefore, the difference of the dynamics between Ca and Mg, and K from O horizon to the surface soil was attributed to the difference in the chemical forms. In addition, the balance of exchangeable cations between the input at the 0 cm soil depth and output at the 50 cm soil depth in both the plots revealed less leaching of these cations from the 50 cm soil depth.
