Improved spring temperature reconstruction using earlywood blue intensity in southeastern China.

Because instrumental observations are too short to fully represent long‐term natural variability, high‐resolution temperature proxy records are essential to understanding past climate and assessing current climate variability in the context of long‐term patterns. In the subtropics, progress in this field has been hampered by a relative lack of long and truly temperature‐sensitive proxy records. In this study, we provide an assessment of the dendroclimatic potential of blue intensity (BI) and ring‐width (RW) measurements from two hot/humid Pinus massoniana sites in China. Our results show that RW exhibits a significant (p <.05) response to precipitation over a hydrological year (previous November to October) and to temperature over the winter–spring season (January to March). We find the earlywood blue intensity parameter to be the most robust parameter for reconstruction purposes; over the 1916–2015 period, it explains 36% of regional‐scale spring season (March–May) temperature variance. Strong agreements between the current reconstruction and observed temperature over a large area of southeastern China implied that our reconstruction exhibited high reliability and large spatial representation. As expected, our reconstructed temperature data are directly correlated with El Niño–Southern Oscillation. These results suggest that there is great potential to use BI to advance our understanding of temperature variability in regions hot and humid climate regimes. However, more studies are needed to understand (1) which subtropical tree species will be appropriate for use and (2) how to overcome biases from differential staining between sapwood and heartwood. [ABSTRACT FROM AUTHOR]