Synchronizations of tree-ring ¹⁸O time series within and between tree species and provinces in Korea: a case study using dominant tree species in high elevations

The current study was initiated to test the synchronizations of tree-ring delta O-18 (hereafter delta O-18(TR)) time series within and between tree species and provinces, which are about 144 km apart from each other in Korea. For the test, a 50-year delta(18)O(TR)time series (1966-2015) was developed using four trees from each tree species which arePinus densifloraandQuercus mongolicafrom Songnisan National Park andTaxus cuspidata,Pinus koraiensis,Abies koreana, andQuercus mongolicafrom Jirisan National Park. Their synchronizations were evaluated usingt-value, Gleichlaufigkeit (Glk), and Expressed Population Signal (EPS). The meant-values and Glk scores within the tree species ranged 5.2-11.2 (p < 0.05) and 69-83%, and between the tree species ranged 6.1-13.2 (p < 0.05) and 73-81%, respectively. The meant-value and Glk score between the regions were 4.3 (p < 0.05) and 72%, respectively. Furthermore, the EPS showed higher than 0.85, which is the generally accepted threshold value in dendrochronology, except forQ. mongolicaat Songnisan National Park for which the value is 0.83 calculated by only two delta(18)O(TR)time series. Based on the statistical results, we concluded that a delta(18)O(TR)chronology established using more than four trees could serve as a promising reference for dating an undated wood without considering the tree species, as well as for research on climate in the past.