A multiple-proxy stalagmite record reveals historical deforestation in central Shandong, northern China

摘要

Evaluating anthropogenic impacts on regional vegetation changes during historical time is not only important for a better understanding of the Anthropocene but also valuable in improving the vegetation-climate models.In this study,we analyzed stable isotopes(δ^18O,δ^13C)and trace elements(Mg/Ca,Sr/Ca)of a stalagmite from Huangchao Cave in central Shandong,northern China.230Th and AMS14C dating results indicate the stalagmite deposited during 174BC and AD1810,with a hiatus between AD638 and 1102.Broad similarities of theδ^18O and trace elements in the stalagmite suggest they are reliable precipitation indexes.Theδ^13C of the stalagmite,a proxy of vegetation change,was generally consistent with local precipitation and temperature variations on a centennial-scale before the 15th century.It typically varied from–9.6‰to–6.3‰,indicating climate controlled C3 type vegetation during this period.However,a persistent and marked increasing trend in theδ^13C record was observed since the 15th century,resulting inδ^13C values from–7.7‰to–1.6‰in the next four centuries.This unprecedentedδ^13C change caused by vegetation deterioration cannot be explained by climate change but is fairly consistent with the dramatically increasing population and farmland in Shandong.We suggest that the increasing deforestation and reclamation in central Shandong began to affect vegetation in the mountain region of central Shandong since the 15th century and severely destroyed or even cleared the forest during the 16th–18th century.