State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Yellow River Estuary Wetland Ecosystem Observation and Research Station, Ministry of Education, Dongying 257200, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China; Yellow River Estuary Wetland Ecosystem Observation and Research Station, Ministry of Education, Dongying 257200, China.
Sci Total Environ. 2021 Jul 1;776:146495. doi: 10.1016/j.scitotenv.2021.146495. Epub 2021 Mar 17.
The mechanisms of biogeomorphic feedbacks and its influencing factors have been extensively studied for pioneer species colonization in tidal environment. However, biogeomorphic impacts of alien species over the entire invasion process coupled with hydro-geomorphologic processes and ecoengineering traits still lack sufficient understanding to forecast salt marsh succession. In this study, we developed a bio-hydrogeomorphic model to account for the tidal platform evolution and vegetation distribution under Spartina alterniflora invasion in the Yellow River Delta, China. Our field observation and modelling results revealed that salt marsh transformed from a stabilized to a self-organized system due to the significant geomorphic-biological feedback under Spartina alterniflora invasion. Tidal channels took shape differently along the elevation gradient of the intertidal platform. Patch-scale feedbacks promoted the channel initiation in the low-elevated zone during early colonization phase. While landscape-scale feedbacks dominated channel incision in the middle to high platform during the mature phase. Specifically, the channel initiation in the middle-elevated ecotone could be attributed to the change from homogenous sheet flow to concentrated channel flow along the marsh edge, which was determined by tidal prism and discrepancy in organism traits. Hence, our study showed that scale-dependent feedback and gaps in ecoengineering capacity of organism determined the morphological variation in the invasive ecosystem. This would provide the insights into biogeomorphic impacts of invasive species and scientific conservation for native ecosystems.
生物地貌反馈机制及其影响因素已在潮滩生境先锋种定殖方面得到广泛研究。然而，外来物种在整个入侵过程中的生物地貌影响，以及水-地貌过程和生态工程特性，仍然缺乏足够的认识，难以预测盐沼演替。本研究建立了一个生物-水-地貌模型，用以描述中国黄河三角洲互花米草入侵下的潮滩平台演变和植被分布。我们的野外观测和模型结果表明，由于互花米草入侵下显著的地貌-生物反馈，盐沼从稳定系统转变为自组织系统。潮汐通道在潮间带平台的海拔梯度上呈现不同的形态。在早期定殖阶段，斑块尺度的反馈促进了低海拔区域的通道起始。而在成熟阶段，中高平台的地貌尺度反馈主导了通道的侵蚀。具体来说，中海拔生态交错带的通道起始可归因于沿沼泽边缘从均匀片状流到集中的通道流的变化，这是由潮汐棱柱和生物特征差异决定的。因此，本研究表明，尺度依赖的反馈和生物生态工程能力的差距决定了入侵生态系统的形态变化。这将为了解入侵物种的生物地貌影响以及保护本地生态系统提供科学依据。
