Individual rings from 1899-1990 were pooled from four radii of four cross-sections obtained from trees at a managed 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 d13C results were highly correlated (r2 = 0.66) and absolute values typically within 0.2-0.3 per mil. Inter-tree variability was estimated as 1-1.5 per mil. The Huangling d13C curve shows an overall downward trend with year-to-year fluctuations of up to 1.5 per mil superimposed. A subset of d13C 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 d13C values, however, could be a consequence of the fairly mesic environment or of human disturbance. Chronologies of isotopic discrimination (D) and Ci/Ca had flat slopes, suggesting the d13C trend was driven by global rather than local effects.
[Radiocarbon Volume 37, Number 2, 1995]