Global climate change and human activities have significantly impacted lake ecosystems at an accelerating rate in recent decades, but the differences between the responses of lake ecosystems to these two stressors remain unclear. Thus an improved understanding of the long-term influences of climatic and anthropogenic disturbances is necessary for the management of lake ecosystems. In order to address these issues, a sedimentary record was obtained from Lake Yilong in Yunnan Province in southwestern China, where the climate and natural environment are dominated by the Indian Summer Monsoon and there is a long history of human occupation and intensive human activity. The chronology is based on AMS 14C dates from 13 samples of plant macrofossils and charcoal, which show that the record spans the last ~12,000 yr. Geochemical indices were used to reconstruct hydro-climatic variations and lake ecosystem responses. The results indicate that a cold and humid climate prevailed from the late Pleistocene to the beginning of the Holocene, which was interrupted by an abrupt decrease in precipitation during 9.7–8.7 ka (1 ka = 1000 cal yr BP, corresponding to the 9.3 ka event). A persistent drying trend occurred during the middle and late Holocene, and there was an increase in the intensity of human activity during the past 1500 years. A comparison of the effects of a natural climatic event and human disturbance reveals contrasting lake ecosystem responses. The lake ecosystem was resilient to the 9.3 ka event and subsequently recovered; however, long-term human activity in the watershed, including deforestation and cultivation, reduced the stability of the lake ecosystem and positive feedback effects were strengthened, leading to the deviation of the system far from its previous stable state. It is concluded that, compared to climate change, human activities have had a much more serious impact on lake ecosystem. © 2021 Elsevier B.V.
Bibliographical noteFunding Information:
This research was supported by the National Natural Science Foundation of China (Grant Nos. 41991251 and 41807442 ), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No. 2019QZKK0601 ) and the United States National Natural Science Foundation (Grant Nos. 1648634 and 1648772 ). We thank Dr. Daniel J. Bain and Miss Yao Zhang for help in the field.
© 2021 Elsevier B.V.
- Abrupt climatic event
- Ecosystem response
- Human impacts
- Indian Summer Monsoon
- Lake Yilong
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PubMed: MeSH publication types
- Journal Article