Holocene vegetation history with implications of human impact in the Lake Chaohu area, Anhui Province, East China

摘要

Palynological analyses of Holocene deposits located about 2 km to the southwest of the Lake Chaohu, Anhui Province, documented well the local vegetation history, its inferred environment and human impacts for the first time. An evergreen and deciduous mixed broad-leaved forest dominated by Cyclobalanopsis and Quercus existed from ca. 10,500 cal b.p. and became fully developed between ca. 8,250 and 7,550 cal b.p. Notable fluctuations occurred in the main components of the flora indicated by the decline in Cyclobalanopsis and other arboreal plants (AP), and an increase in terrestrial herbs between ca. 7,550 and 3,750 cal b.p., inferring the progressive opening of the forest under considerable human interference, which largely agrees with the archaeological evidence. After ca. 3,750 cal b.p., the broad-leaved forest largely gave way to terrestrial herbs, and never again recovered. Pinus continued to rise alongside the majority of herbs between ca. 3,750 and 2,000 cal b.p., then also declined after ca. 2,000 cal b.p. Human influence on the natural vegetation displayed in the pollen diagram seems to increase greatly up the core. The disappearance of broad-leaved forest indicates significant human impact after ca. 3,750 cal b.p., which is consistent with both the archaeological evidence and historical records. From that time the natural environment in the study area was subjected to long-standing pressure from increasing farming and population.