DENDROCLIMATOLOGICAL STUDIES OF PICEA LIKIANGENSIS AND TSUGA DUMOSA IN LIJIANG, CHINA
Expansion of climate proxy records over space is needed for improving our knowledge of past climate variability. Here we report on a 112-year tree-ring chronology of Picea likiangensis (Franch.) E.Pritz. and a 165- year tree-ring chronology of Tsuga dumosa (D.Don) Eichler for the Lijiang area, northwestern Yunnan, China. Mean correlation coefficients of tree-ring width series among individual trees are 0.48 for P. likiangensis and 0.45 for T. dumosa, indicating a growth response to common environmental variability. Analysis of climate-growth relationships shows that the radial growth of P. likiangensis is mainly negatively correlated with temperature from December of the prior growth year to May of the growth year, and that of T. dumosa is mainly positively correlated with precipitation of January and May in the growth year. We further found that the chronology of T. dumosa can be used to reconstruct the May-June Palmer Drought Severity Index. The reconstruction shows that major wet periods occurred in the 1860s, 1910s and 1940s, and drought periods in 1892–1905, 1914–1924 and 1928–1938. The moisture condition of the late 20th century is characterized by a near-normal state from the 1950s to the 1970s and an increasing trend from 1982 to 2003.