Contrasting ecosystem responses to climatic events and human activity revealed by a sedimentary record from Lake Yilong, southwestern China
Contrasting ecosystem responses to climatic events and human activity revealed by a sedimentary record from Lake Yilong, southwestern China
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中国西南部仪龙湖的沉积记录揭示了生态系统对气候事件和人类活动的反应对比
DOI：
10.1016/j.scitotenv.2021.146922
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发表时间：
2021
影响因子：
9.8
通讯作者：
Zhou Aifeng
中科院分区：
文献类型：
--
作者：
Yuan Zijie;Wu Duo;Niu Lili;Ma Xuyi;Li Youmo;Hillman Aubrey L.;Abbott Mark B.;Zhou Aifeng
近几十年来，全球气候变化和人类活动对湖泊生态系统产生了显著的加速影响，但湖泊生态系统对这两种压力的响应差异尚不清楚。因此，更好地了解气候和人为干扰的长期影响对于湖泊生态系统的管理是必要的。为了解决这些问题，在位于中国西南部的云南省仪陇湖获得了沉积记录，那里的气候和自然环境以印度夏季风为主，人类占领历史悠久，人类活动强烈。该年表基于13个植物大型化石和木炭样品的AMS14C测年，表明这一记录跨越了过去的12000年。利用地化指数重建水文气候变化和湖泊生态系统响应。结果表明，晚更新世至全新世初气候以冷湿为主，9.7~8.7ka(1ka=1000calyrBP，对应9.3ka事件)降水骤减中断。全新世中晚期出现了持续的干旱化趋势，近1500年来人类活动强度有所增加。通过比较自然气候事件和人为干扰的影响，可以看出湖泊生态系统的反应截然不同。湖泊生态系统对9.3ka事件有一定的恢复能力，但流域内人类的长期活动，包括砍伐森林和耕作，降低了湖泊生态系统的稳定性，加强了正反馈作用，导致系统偏离了以前的稳定状态。与气候变化相比，人类活动对湖泊生态系统的影响要严重得多。
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 AMS14C 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.