Effects of climate on the tree ring density and weight of Betula ermanii in a cool temperate forest in central Japan

Key Message The tree ring weight of Betula ermanii was primarily controlled by the ring width, but not by its ring density. The climate responses of them were clarified by dendrochronological analysis. Abstract Global warming scenarios have made the understanding of carbon sequestration changes in the stems of forest trees important. However, there is a lack of understanding about climate change’s effects on the wood density of hardwood, which is a crucial indicator of wood biomass. Therefore, we investigated the effects of climatic factors on the ring density and ring weight of B . ermanii, a dominant tree species in cool temperate regions and subalpine regions of Japan. We calculated the annual ring weight growth by multiplying the ring width and density. We developed the residual chronologies of the ring density and weight and performed a correlation analysis between the chronologies and the climate data. We deduced that the ring density was independent of the ring width for individual cores. The ring weight chronology showed a positive correlation with the ring width but not with ring density. The ring density decreased due to higher temperature, long sunshine duration, and less precipitation from mid-July to early October in the previous year. Conversely, those from mid-June to mid-August increased the ring density in the current year. The previous year’s high nighttime temperature in autumn and dry conditions during the current year’s summer decreased the ring weight, similar to the climate responses of ring width. Therefore, we concluded that ring weight was not controlled by ring density, but majorly regulated by ring width. Conclusively, this study’s results can evaluate the impact of climate change on the carbon sequestration potential of the stem of B. ermanii .