Impacts of human activities on ecosystems during the past 1300 years in Pingnan area of Fujian Province, China
Résumé
A high-resolution pollen record obtained from Pingnan County, Fujian province in China, provides new insights into the nature of ecosystem changes and the relative importance of human disturbances during the last 1300 years. Pollen and stable carbon isotope data indicate that prior to about 800 cal BP the study area was covered by a natural forest, dominated by evergreen broad-leaved trees (Castanopsis and Quercus). This primeval vegetation was then progressively replaced by the secondary vegetation after ∼800 cal BP. Increases of Gramineae pollen since ∼800 cal BP and a sharp rise in Pinus pollen after ∼450 cal BP clearly express the expansion of human impacts, reflecting the expansion of farming and the succession of a now-widespread Pinus massoniana after alteration of the primeval vegetation. Taxonomic diversity analysis also shows that the floristic diversity is higher during the period of human disturbances than in the earlier part of the record, a phenomenon that has been observed in temperate pollen records where human activities increased.