Phytoliths and microcharcoal at Jinluojia archeological site in middle reaches of Yangtze River indicative of paleoclimate and human activity during the last 3000 years

A variety of phytoliths, together with prolific microcharcoal particles, sponge spicules and diatoms were extracted and identified in four cultural layers from an archeological site at Jinluojia, Macheng, Hubei Province, Central China. The warmth (Iw) and aridity (Iph) indices calculated from grass phytoliths reveal warm and wet periods during the West Zhou, early East Zhou, Tang and Song Dynasties whilst cool and dry periods occurred during the late East Zhou, Ming and Qing Dynasties. The paleoclimate conditions reconstructed on the basis of grass phytoliths extracted from archeological sediments are in agreement with those from natural sediments in the Middle Yangtze region. In contrast, the woody phytoliths show a positive correlation with microcharcoal particles, suggesting an anthropogenic contribution to the woody phytoliths from the use of woody plants for fuel during cooking and heating. Two episodes of the enhanced abundance of woody phytoliths and microcharcoal particles were found to occur at East Zhou Dynasty and from Ming and Qing Dynasties to the Present, proposed to be a consequence of the population expansion and/or the frequent wars.