Cryptomeria japonica is distributed on the Pacific Ocean side and reproduces only by seedling; however, C. japonica var. radicans is distributed on the Japan Sea side and reproduces by both seedling and layering. Until now, there has been no report that C. japonica on the Pacific Ocean side regenerates by layering. In this study, the regeneration system of C. japonica in a national forest of Miyagi Prefecture Ishinomaki City was investigated using DNA analysis. C. japonica growing in the study plot was divided into seven genets and 40 single ramets, clearly suggesting that C. japonica at this site regenerates not only by seedling, but also by layering. The strong winds and low temperature appear to be key factors in layering reproduction at this site.

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