College of Earth and Environmental Sciences, MOE Key Laboratory of Western China's Environmental Systems, Lanzhou University, Lanzhou 730000, China.
College of Earth and Environmental Sciences, MOE Key Laboratory of Western China's Environmental Systems, Lanzhou University, Lanzhou 730000, China.
Sci Total Environ. 2021 Aug 20;783:146922. doi: 10.1016/j.scitotenv.2021.146922. Epub 2021 Apr 17.
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 C 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.
全球气候变化和人类活动在近几十年以加速的速度显著影响了湖泊生态系统，但湖泊生态系统对这两种胁迫的响应差异尚不清楚。因此，需要更好地了解气候和人为干扰的长期影响，以管理湖泊生态系统。为了解决这些问题，在中国西南部云南省的宜良湖获得了一份沉积记录，该地区的气候和自然环境主要受印度夏季风的影响，且人类居住和人类活动密集的历史悠久。该年代学基于来自 13 个植物大化石和木炭样本的 AMS C 年代测定，表明该记录跨越了最近约 12000 年。地球化学指标被用来重建水-气候变化和湖泊生态系统响应。结果表明，从更新世晚期到全新世早期，气候寒冷潮湿，但在 9.7-8.7ka（1ka=1000 年 cal BP，对应于 9.3ka 事件）期间，降水突然减少，气候出现了一个短暂的中断。中全新世和晚全新世期间一直持续干旱趋势，在过去 1500 年里，人类活动的强度增加。比较自然气候事件和人类干扰的影响揭示了截然不同的湖泊生态系统响应。湖泊生态系统对 9.3ka 事件具有弹性，并随后恢复；然而，流域内的长期人类活动，包括森林砍伐和耕作，降低了湖泊生态系统的稳定性，并加强了正反馈效应，导致系统偏离其先前的稳定状态。因此得出结论，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。
