Temperature signals in tree-ring width and divergent growth of Korean pine response to recent climate warming in northeast Asia

Six Korean pine (Pinus koraiensis) tree-ring chronologies were developed in northeast Asia. Growth trends in recent decades were compared and main factors limiting growth were identified within each site. The spatio-temporal stability of climate-growth relationships were also tested for important climate variables. Results showed that temperature played a key role in controlling Korean pine growth, while recent growth showed strong geographic patterns. Tree growth in recent decades at two south and high altitude sites increased with temperature, remained constant for two low-altitude sites at its central distribution, and decreased for two moderately altitude sites at its distribution north margin. Tree-ring principle of the ecological amplitude was proved again, i.e., trees growing near the margin of its natural range has higher climate sensitivity. Drought stress due to temperature increases appeared to be a primary reason for Korean pine growth decline, whereas varying degrees of drought stress were distinctly dependent on site conditions. Variation of climate-growth relationships over time for different sites was consistent with their recent growth. Two average chronologies for six sites revealed a decreased (Heihe, Mudanjiang, and Liangshui) or inverse (Dunhua, WPS, and Wuying) growth response to rapid warming since 1980, which was possibly related to unique site conditions and various large-scale climate impacts. In addition, our results indicated that modeling possible reactions of forest to global warming or reconstructing past climate need to consider diverse spatiotemporal variations of climate-growth relationships of Korean pine in northeast Asia.