| 摘要: |
| 伴随湖泊营养负荷的增加、湖泊水生植被衰亡、藻类增长，湖泊会由草型稳态向藻型稳态转变，一旦稳态发生转变，将很难再逆转，严重影响湖泊生态系统功能和服务价值。从湖泊草藻长期演变的视角，开展突变点识别，辨析湖泊稳态转换过程，有助于早期预判湖泊生态灾变风险，为湖泊生态保护、修复和综合治理提供决策支持。本研究以梁子湖为例，通过遥感解译的长时序草藻数据集，结合文献搜集的长期水环境关键因子数据，分析水环境变化并识别水生植被覆盖度的突变点，解析湖泊稳态转换过程。结果表明，34年来，梁子湖生态系统发生显著变化：在1990—2016年间，湖泊水质逐渐恶化，水环境因子发生显著变化，透明度在2010年发生突变，高锰酸盐指数（CODMn）和总氮（TN）浓度在2011年发生突变，总磷（TP）浓度在2016年发生突变；湖泊发生稳态转换的关键时间为2016年，水生植被覆盖度发生突变，沉水植被大幅减少，湖泊草型生态系统崩溃；在2017—2023年间，湖泊水生植被衰亡，并在2022—2023年连续暴发藻华，湖泊已转变为藻型生态系统。综合各因子的突变时期，可将梁子湖从草型到藻型生态系统转换分成四个阶段：以沉水植被为主导的草型稳态—湖泊营养负荷显著增加—水生植被突变（稳态转换）—以浮游藻类为主的藻型稳态。本研究方法和结果，可为梁子湖生态修复与治理决策提供理论支撑，同时也为长江中下游的其他浅水湖泊生态风险早期预警、修复与治理提供了方法支撑与科学参考。 |
| 关键词: 梁子湖 稳态转换 草藻演变 湖泊生态系统 |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Analysis of regime shift process based on macrophyte- phytoplankton changes: A case study of Lake Liangzi |
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Xu Ying1, Luo Juhua1, Zhai Jinlong1, Mao Zhigang1, Duan Hongtao1, Meng Di2, He Bo2, Lu Lu2
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1.Key Laboratory of Lake and Watershed Science for Water Security,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences;2.Institute of Dianchi Plateau Laes
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| Abstract: |
| Lakes undergo a transition from a macrophyte-dominated state to a phytoplankton-dominated state, accompanied by an increase in lake nutrient loads, a decline of aquatic vegetation (AV), and the proliferation of algae. Once the regime shift occurs, it is difficult to reverse, seriously affecting the ecological functions and service values of the lake ecosystem. Identifying tipping points and analyzing the process of lake regime shifts can help predict potential ecological risks, providing decision support for lake ecological protection, restoration, and integrated management. In this study, we take Lake Liangzi as an example to analyze water environmental changes and identify the tipping points of AV, and to deconstruct the process of lake state shifts. We constructed a long-term dataset of AV and algal bloom (AB) data, interpreted from remote sensing and combined with long-term data series of key water environmental factors, in order to conduct a thorough analysis. Over the past 34 years, the ecosystem of Lake Liangzi has undergone significant changes. The lake water quality gradually deteriorated between 1990 and 2016. Transparency experienced a mutation in 2010, while the permanganate index (CODMn) and total nitrogen (TN) concentrations mutated in 2011, and total phosphorus (TP) concentration shifted in 2016. The critical year for the lake"s state shift occurred in 2016, with a mutation in AV coverage, especially in submerged aquatic vegetation (SAV), indicating the collapse of the AV-dominated state. Between 2017 and 2023, the AV dramatically declined in Lake Liangzi, and there were consecutive AB outbreaks in 2022-2023, suggesting that the lake has transitioned to a phytoplankton-dominated ecosystem. Integrating the mutation periods of various factors, the regime shifts in Lake Liangzi can be divided into four stages: (1) the macrophyte-dominated state; (2) significant increase of nutrient loading; (3) degradation of AV; (4) phytoplankton-dominated state. Our approach and findings can provide theoretical support for ecological restoration and management decisions of Lake Liangzi. They also offer scientific reference for the early warning, restoration, and management of other shallow lakes in the middle and lower reaches of the Yangtze River. |
| Key words: Lake Liangzi regime shift evaluation of macrophyte-algae community lake ecosystem |
