生态系统多稳态研究进展

在多稳态的生态系统中,外力可能导致生态系统状态突然之间发生不可逆转的转变,从而达到一个新的平衡状态。但目前对多稳态理论的系统研究很少,如何使用预警信号来预测生态系统的状态转变依旧是个难题。通过多稳态理论的梳理提出了一个更加综合的多稳态定义,并以放牧模型为例,系统总结了多稳态理论的相关概念,将多稳态理论应用在生态系统演替和扰沌理论的解释中;通过对生态系统稳态转换预警信号的原理、优缺点和应用条件的分析,对不同尺度下多稳态的研究方法进行了归纳;最后提出了目前多稳态领域的研究问题和未来的研究重点。结果表明：（1）将时间和空间预警信号结合在一起,并量化正确预警信号的概率,对错误预警信号的比例进行加权,可能会提供更准确的稳态转换的预报。（2）定量观测试验适用于小尺度的研究,而较大尺度的研究则采用简化的模型来模拟研究,选择正确的尺度极有可能改变预警信号的可靠性。（3）结合多稳态理论研究生态系统临界转换和反馈控制机制,并将基于性状的特征指标和进化动力学纳入其中,是生态系统修复实践的重要研究方向。（4）将多稳态相关理论和生态保护管理政策的实践相结合,是多稳态理论未来应用的前景。本研究为多稳态理论和实践的深入研究提供科学支撑。

Review of alternative stable states theory in ecosystem

In an alternative stable state (ASS) ecosystem, tipping points lead to abrupt and possibly irreversible shifts between alternative ecosystem states. However, there are only a few systematic studies on the ASS theory at present, and how to use a variety of early warning signals to predict the regime shift in the ecosystem at different scales is still a difficult problem. Besides, critical transitions are difficult to predict because the state of the system usually shows little change before the transition. In this review, firstly, a more integrated definition of ASS has been put forward through reorganizing of ASS theory from different previous literatures. Alternative stable states are defined:under the same external force or internal force driving, the structure, material composition and energy flow of the ecosystem will change into two or more different stable states, which are maintained by negative feedback loops. Then, the relevant concepts of ASS theory were systematically summarized by the model of the grazing animals on pasture land. Furthermore, ASS theory has been originally applied to interpret succession and panarchy theory in the ecosystem. Secondly, the principles, advantages, disadvantages, as well as application conditions of the early warning signal of regime shift in an ecosystem were analyzed, and the research methods of ASS theory at different ecological scales were summarized. The mathematical reason for critical slowing down leads to an increase in the autocorrelation and variance of the fluctuations in a stochastically forced system approaching a tipping point is illustrated by the autoregression model. Finally, the current research problems in the field of ASS and the focus of future research were put forward. The review results show that:(1) combining different early warning signals could provide a more accurate prediction of the tipping point by quantifying the probability of correct early warning signals and weighting the proportion of wrong early warning signals. (2) The quantitative experimental observation experiment is suitable for small-scale research, while larger-scale research usually uses a simplified model to simulate the results. Moreover, choosing the correct scale is very likely to improve the reliability of the early warning signal in predicting the regime shift. (3) The application of ASS theory would be important for ecosystem restoration by studying the critical transition and feedback control mechanism combining the trait-based characteristic indicators and evolutionary dynamics. (4) Applying ASS theory into the practice of ecological protection and management policy is very promising. This study provides scientific support for the further research of ASS theory and practice.