Reconstruction of Regeneration Process Using Selective Cutting Practice in a Chamaecyparis obtusa Forest with an Undergrowth Lacking Dwarf Bamboo by Tree-ring Analysis

The natural regeneration processes of a Chamaecyparis obtusa forest using selective cutting were reconstructed by tree-ring analysis, and the effects of disturbance on the regeneration were examined. This research was conducted at the Akasawa Experimental Forest, Kiso district, central Japan, in a stand lacking dwarf bamboo in the undergrowth. About 30 years after a selective cutting conducted in 1984-1986, the height distribution of regenerating C. obtusa individuals consisted of two groups, a larger group with heights of 2-3 m or more, and a smaller group. Tree-ring analysis revealed that the former corresponded to the advanced population recruited before the cutting and the latter to the newly recruited population emerging after the cutting. The growth of the advanced population was vigorous from 1945 to 1960, but then declined greatly. Growth increased after the cutting, and again after an undergrowth removal conducted in 1997. These findings suggest that there was a canopy opening event around 1940 that improved light conditions and caused the recruitment of the advanced population. Subsequent inferior light conditions reduced sapling growth and survival, but the selective cutting prevented their ultimate extinction and allowed for a return to vigorous growth. The advanced population will eventually play the leading role in the next generation forest, and the newly recruited population will function as prospective successors in the future. Repeated disturbances at several-decade intervals that improve light conditions are likely to contribute to the success of natural regeneration practice. © 2023 Nihon Ringakkai. All rights reserved.