December-March temperature reconstruction from tree-ring earlywood width in southeastern China during the period of 1871-2016.

Extremely cold temperatures are a significant threat to agriculture and transportation in winter in southeastern China. However, due to the shortness of instrumental records and the scarcity of long-term temperature reconstructions, more high-quality temperature reconstructions are still needed to fully examine their spatial-temporal variability over the past several centuries. In this study, we built an earlywood width (EWW) chronology, a latewood width (LWW) chronology, and a tree-ring width (TRW) chronology using tree-ring samples of Pinus taiwanensis Hayata from the western Tianmu Mountains and the Xianyu Mountains in southeastern China. The tree growth-climate relationships were analyzed, and we found the strongest correlation between December and March mean temperature and the EWW chronology. The December-March mean temperature history was then reconstructed over the period of 1871-2016 using a linear regression model, which is the first EWW-based temperature reconstruction in southeastern China. With a higher explained variance (47.0%) than that (31.7%) of a previous reconstruction using a TRW chronology, the quality of the model has largely improved. This reconstruction was also comparable with other nearby records, further demonstrating the reliability of our new model. Furthermore, our reconstruction exhibits a significantly negative relationship with the East Asian winter monsoon index (EAWMI) since the 1920s, which may be attributed to the obviously enhanced EAWMI thereafter.