景观系统突变的级联效应研究

Abrupt shift exists in a wide range of ecological, environmental and social systems. When abrupt shift takes place, it could produce profound impacts on human well-being. Trigger mechanisms and early-warning signals of abrupt shift are difficult to reveal because of complex system interactions. Landscapes, as complex hierarchical systems, can manifest abrupt shift in terms of compostion, structure and fucntion. The abrupt shift that occurs on some specific state variables characterizing landscape pattern is possibly transferred within and between the landscape systems, ultimately influencing landscape processes and functions. This phenomenon can be termed as cascading effect of abrupt shift in landscape systems. Targeting the representative landscapes in the Yangtze Delta, the present research project aims to detect the abrupt shift in the state variables of landscape pattern using the "3S" technology, spatial analysis and time series analysis approaches. Also, the landscape-level process that materials are trasport from land to water in response to the abrupt shift of pattern variables is to be studied through in-situ investigations of the aquatic ecosystems. By coupling the dynamic processes of different state variables, we attempts to reveal the transfer path and mode of abrupt shift within/between landscape systems, as well as the spatial heterogeneity and scaling effect. We seek to identify the early-warning signals of abrupt shifts in landscape systems, elucidate the mechanisms of generating and transfering abrupt shift, and develop a cascading model of abrupt shift. We hope these studies could help to deepen understandings on landscape evolution and provide decision support for landscape management and optimal configuration of land use.

突变现象普遍存在于生态、环境和社会系统中，并对人类福祉产生深远影响。由于系统相互作用的复杂性，突变的触发机制和预警信号成为研究难点。景观作为复杂等级系统，其组成、结构和功能都可能表现突变特征；特定景观格局参量发生的突变可能在景观系统内和不同景观系统间发生作用传递，并最终影响到景观过程和功能，可称之为景观系统突变的级联效应。本项目以长江三角洲内典型景观为对象，利用3S技术、空间分析和时序分析等方法检测景观格局状态参量的突变现象，并通过对水生态系统的定位观测，研究陆源物质向水体的运移输入过程对格局参量突变的响应；在此基础上对不同状态参量的变化过程进行耦合分析，旨在揭示突变在景观系统内/间的作用传递路径、传递方式及其空间异质性和尺度效应，寻找景观系统突变的预警信号，阐明突变发生和传递的动力学机制，建立景观系统突变级联反应模型，以期深入理解景观演化规律，为景观管理和土地利用优化配置提供决策支持。

突变现象普遍存在于生态、环境和社会系统中，并对人类福祉产生深远影响。景观作为复杂等级系统也可能表现突变特征，但关于景观系统突变的理解尚非常有限。本项目以植被景观、城市化景观等多种景观系统为对象，利用3S技术、格局分析以及过程模型等方法检测景观系统中的突变现象，旨在揭示景观系统突变的表现形式及其空间异质性和尺度效应，阐明突变发生和传递的动力学机制。研究发现植被垂直结构的多众数特征可以作为植被景观系统多稳态与突变的新证据，为景观系统多稳态的探测和机理研究提供了新的线索；发现寒带系统的多稳态为“草原—寒带森林—疏林地—冻原”，修正了近期PNAS论文的结果，对于预测全球变化的生态响应具有重要意义；发现了生物个体间的小尺度正反馈作用可以成为整个植被景观系统多稳态与系统突变的一般性机制，表明植被景观突变的发生可能在局部的微生境尺度上级联放大到整个景观水平；提出了全面反映图灵格局、不规则格局的植被格局特征的机制，为退化植被的修复实践提供了重要参考；利用基于拓扑的城市增长模式识别方法揭示了增长模式周期性节律以及城市景观结构突变的规律，并定量揭示了影响城市增长模式的景观驱动机制，为实现城市的精明增长提供了重要的理论支持；发现了局部尺度景观格局特征对宏观生物地理尺度上物种多样性格局的显著影响，为经典生物多样性地理格局理论提供了新的关注点。本项目研究成果对于理解景观系统非线性动态机理具有重要理论价值，特别是在植被景观多稳态和突变机制、城市景观相变的刻画等方面获得了创新性的研究成果。