A Single-Year delta-13C Chronology from Pinus tabulaeformis (Chinese Pine) Tree Rings at Huangling, China

Abstract

Individual rings from 1899-1990 were pooled from four radii of four cross-sections obtained from trees at a forest site near Huangling, north of Xian in north central China. Splits of wood ground to 20-mesh were analyzed independently at both the Xian and Arizona laboratories, using their respective methods for cellulose isolation, combustion and mass-spectrometric analysis. The delta-13C results were highly correlated (r2 = 0.66) and absolute values typically within 0.2-0.3ppm. Inter-tree variability was estimated as 1-1.5 ppm. The Huangling delta-13C curve shows an overall downward trend with year-to-year fluctuations of up to 1.5 ppm superimposed. A subset of delta-13C maxima corresponded with below-normal precipitation and above-normal temperature in May and June, and minima were associated with above-normal precipitation and below-normal temperature in May and June, perhaps signaling early arrival of the East Asian Summer Monsoon. The generally poor climate correlations with all delta-13C values, however, could be a consequence of the fairly mesic environment or of human disturbance. Chronologies of isotopic discrimination (Delta) and Ci/Ca had flat slopes, suggesting the delta-13C trend was driven by global rather than local effects.