δ13C, δ18O and deposition rate of tufa in Xiangshui River, SW China: implications for land-cover change caused by climate and human impact during the late Holocene

Abstract

AbstractMeasurements of δ13C and δ18O values of the riverine tufa samples dated by the accelerating mass spectrometry-14C method have been used for discussion of land-cover change in the catchment area of the Xiangshui River, SW China during the late Holocene. The results show that tufa was deposited in this short river only between c. 4280 and c. 110 years BP. Based on the characteristics of δ13C values of the complete tufa profile in the river, three stages of land-cover conditions in the headwater area could be identified. The earliest, Stage I, contained the most extensive vegetation cover with mainly C3 plants, as shown by the lightest δ13C value, whereas the latest, Stage III, had the least land cover, reflected by the heaviest δ13C value. By comparison of speleothem and historical records, it was found that the land cover in Stage I was controlled mainly by climate change, whereas the land-cover changes in the later two stages were most probably related to major human disturbance (land use), especially since the Qin Dynasty and Ming Dynasty, in the headwater area of the river.