TREE-RING WIDTH AND STABLE CARBON ISOTOPE COMPOSITION OF JAPANESE CYPRESS IN THE LAKE BIWA AREA, CENTRAL JAPAN, AND THEIR HYDROLOGIC AND CLIMATIC IMPLICATIONS

Chronologies of tree-ring width and stable carbon isotope composition of Japanese cypress were developed to help reconstruct a 300-year record of past hydrologic and climatic environments in the Lake Biwa area, central Japan. Site chronologies were built with 37 trees for ring width and four trees for carbon isotope composition, respectively. Correlation analysis with monthly climatic data revealed that radial growth of the trees is related to temperature in early spring, precipitation (or number of precipitation days) in early summer and precipitation in previous-year summer to autumn. Tree-ring cellulose carbon isotopic composition is correlated most significantly with the number of precipitation days in early summer months. Consequently, a chronology of the number of precipitation days in May was reconstructed by multiple regression analysis with ring-width and carbon-isotope predictors and was validated by comparison with the recent observed record.