Climate and landscape change favouring early rice agriculture and appreciable human impact: Evidence from sediment δ13C in eastern China

Abstract Kuahuqiao site, famous for its early rice cultivation, is taken to be a typical case of how agriculture emerged in a littoral environment in the early Holocene. However, the lack of fire history and local climatic reconstruction has hindered the detailed picture of agricultural origins and development. Here we report new records of TOC, BC, δ 13CTOC, δ 13CBC, and C/N, alongside published pollen and charcoal data. Our δ 13CTOC and C/N confirm the previously-proposed formation of wetlands, which offered favorable landscapes for rice paddy agriculture, prior to the appearance of the Kuahuqiao culture. Based on BC, δ 13CTOC, and δ 13CBC records we suggest a hotter but drier climate that would have benefited rice agriculture by augmenting the distribution of wild rice and C4 herbs. In addition, δ 13CTOC shows a decreased C3/C4 ratio as a signal of human occupation with manipulation of forest for hunting-gathering or/and land clearance for agriculture. Combined δ 13CBC and BC records oppose the proposal of intense fire use in early agriculture and suggest that fire use was constrained to domestic purposes. Flood events which seem to have terminated the Kuahuqiao culture left impressions in TOC, BC, δ 13CTOC, δ 13CBC.