Coffin timber from southeastern China as a tree-ring archive for paleoclimate research

Abstract

Tree-ring chronologies provide high-resolution climate records, playing a crucial role in the study of paleoclimate and social history. In China, long chronologies are mainly concentrated on the Tibetan Plateau and surroundings, whereas those in southeastern China rarely exceed 200 years. To develop a longer chronology, we collected 315 coffin wood samples buried during the Song (960–1279 CE) to Ming Dynasty (1368–1644 CE) period from five archaeological sites in Changzhou, Jiangsu Province, in the lower Yangtze River basin. Using dendrochronological crossdating, we constructed a 344-year floating tree-ring width chronology spanning the late Tang to the Song Dynasty. Radiocarbon dating further constrained its temporal span to approximately 780 to 1150 CE. The chronology shows a significant positive correlation with solar irradiance, exhibiting notably reduced growth during the Oort solar minimum (∼1021–1060 CE) and intervals of weakened South Asian summer monsoon. We further identified temporal shifts in coffin types and wood selection. Compared with those from the Song dynasty, coffins from the Ming period exhibit a greater number of tree species and a higher proportion of fast-growing, young trees, reflecting the ongoing depletion of primary forests in the lower Yangtze region. Some large coffins relied on timber acquired through long-distance trade, increasing the diversity of wood sources and posing challenges for cross-dating. These findings suggest that coffin assemblages preserve not only climatic signals but also evidence of environmental change and shifting patterns of resource use.