Vegetation and climate changes in the Changjiang (Yangtze River) Delta, China, during the past 13,000 years inferred from pollen records

Abstract

A high-resolution pollen record from 2 boreholes from the Changjiang (Yangtze River) delta shows a series of well-defined changes in vegetation and climate over the last 13,000 yr . In latest Pleistocene to early Holocene time (12,900– 10,300 cal yr BP), pollen dominated by the xerophytic herb Artemisia and common conifers indicate coniferous forest and grasslands and a cool, dry climates, possibly represented by the Younger Dryas. From 10,300 to 9000 cal yr BP, a warm, wet climate fostered the development of mixed broadleaved evergreen–deciduous forests to grow on the grasslands and surrounding hills and uplands. From 9000 to 7600 cal yr BP, the dominance of conifers and the reduction in broadleaved evergreen trees pollen suggest cool, dry conditions. The mid-Holocene “hypsithermal” (7600– 4800 cal yr BP) is represented by a large expansion of subtropical evergreen–deciduous broadleaved forests. Between 4800 and 1300 cal yr BP, which corresponds to a Neoglacial period elsewhere, conifers are dominant, along with common herbs, whereas the area with broadleaved evergreen trees shrink under the cool, dry conditions. The first occurrence of Fagopyrum pollen at 4500 cal yr BP suggests human influence. The significant change in arboreal and herbaceous pollen after 1300 cal yr BP reflects widespread intensive human influence.