An Attempt of Combining Oak and Pine Trees to Enhance Monsoonal Precipitation Reconstruction in the East Qinling Mountains

Short-term meteorological observations often limit our understanding of regional climate change over historical periods. Dendroclimatology provides an effective means for overcoming this limitation by extending the climate record. In China, most tree-ring studies focus on coniferous species. But this study innovatively combines both Liaodong oak and Chinese pine trees to establish a new synthesis chronology in the East Qinling Mountains. The new synthesis chronology showed a significantly high correlation with observed April–June precipitation (r = 0.747, n = 41, p < 0.001), while the individual chronology of oak or pine trees failed to meet the threshold for quantitative climate reconstruction (R² > 40%). Using this synthesis chronology, we reconstructed a 163-year precipitation series that offers a robust spatiotemporal representation of the marginal East Asian Summer Monsoon (EASM) region through spatial correlation analysis and comparison with surrounding hydroclimate reconstructions. The several extreme drought periods (1871–1881, 1917–1931, and 1957–1973) and extreme wet periods (1888–1899, 1906–1916, and 1985–1995) were detected from the reconstruction. Additionally, it showed significant synchronisation with the EASM indices (p < 0.02) at interannual time scales, while PDO and AMO influenced precipitation variability at multidecadal scales. These findings demonstrate that combined broad-leaved and coniferous tree-ring chronologies can effectively capture large-scale atmospheric circulations.