The Potential of Using Tree-Ring Data from Jeju Island to Reconstruct Climate in Subtropical Korea and the Western North Pacific

Annual rings from trees have been used to infer past climate variability beyond the observational records. Here, we assess if two conifer species from the humid subtropical island of Jeju, South Korea, can be used as proxies for past regional climate variability and large-scale ocean current variability, such as the Kuroshio Current, over the Western North Pacific. Korean red pine (Pinus densiflora) and Korean fir (Abies koreana) were sampled close to their altitudinal limits of distribution on the southern slopes of the volcano Mt. Halla at 1320 m and 1640 m a.s.l., respectively. Comparison with climate variables from nearby meteorological stations indicated a significant positive association between temperature in January/April and Korean red pine growth, which suggests that the red pine can be used to reconstruct mid-winter/spring temperatures back in time. Positive correlations were also found between the tree-ring growth and October (for Korean fir) and January (for Korean red pine) precipitation. Moreover, pine tree growth showed significant multi-month associations with sea surface temperatures over the Western North Pacific and variability of the Kuroshio Extension. The results suggest that subtropical trees from South Korea can be used as indicators of past climate variability on local to regional scales, and possibly also to infer the past variability of the Kuroshio Current in the Western North Pacific.