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福建漳江口滨海湿地稳态结构演替及其驱动因素

Alternative stable states of coastal wetland ecosystems of Zhangjiang Estuary, Fujian, China

  • 摘要: 滨海湿地多稳态是动力、地貌、植被长期互馈耦合的结果,其与生态系统景观结构、生态功能及系统健康可持续发展密切相关,也是滨海湿地生态研究的基础核心问题。围绕滨海湿地多稳态结构演变,本文选取漳江口滨海湿地作为多稳态研究典型靶区,基于多年遥感影像的归一化植被指数(Normalized Difference Vegetation Index,NDVI)“峰态”判定法、信息熵理论等方法,辨识不同时期生态系统稳态特征,分析稳态结构演变的主要驱动因素,并基于稳态面积信息熵变化趋势分析滨海湿地生态系统稳态结构的有序性。结果表明,漳江口滨海湿地从单稳态向多稳态结构转换,稳态结构具有显著的阶段性变化特征;互花米草入侵导致生态系统稳态结构逐步转换并最终形成“红树林-互花米草(Spartina alterniflora)-光滩”多稳态,而滩涂养殖抑制了互花米草扩张,某种意义上维持着系统稳态结构稳定。在自然演替与人类活动共同作用下,生态系统稳态信息熵呈波动熵增趋势,表明漳江口滨海湿地处于自适应调整阶段,生态系统正处于无序发展,稳态结构尚不稳定,后续应密切研判互花米草扩散动态并设计有关生态修复预案,以保障生态系统平稳有序发展。

     

    Abstract: The alternative stable states (ASS) of coastal wetlands is the results of long-term mutual feeding and coupling between dynamics, geomorphology and vegetation, and is closely related to the landscape structures, ecological functions and healthy sustainable development of ecosystem. ASS is also the core problem of coastal wetland ecological research. Focus on the evolution of ASS, this article selected the coastal wetland in Zhangjiang Estuary as the study area. Multi-temporal remote sensing images and the Normalized Difference Vegetation Index (NDVI) "kurtosis" determination, threshold segmentation, information entropy theory were used to identify the characteristics and evolution of ASS and its driving factors in different times, and the orderliness of the ASS of the coastal wetland ecosystem was analyzed based on the changes of information entropy. Results showed the ASS of the coastal wetland in Zhangjiang Estuary have changed from monostable to multistable structure with significant evolution stages. The invasion of Spartina alterniflora led to a gradual transformation of ASS and finally formed the “Mangrove- S. alterniflora-Mudflat” stable states, while the land use of mudflat culture inhibited the expansion of S. alterniflora and in a sense, maintained the stability of ASS. Under the joint actions of natural processes and human activities, the coastal wetland in Zhangjiang Estuary was in the self-adaptive adjustment with an altered increasing of information entropy, indicating the ecosystem was in disordered development. In the future, the expansion of S. alterniflora and corresponding restoration plan should be paid more attention to support stable and orderly development of the coastal wetland ecosystem.

     

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