南流江河口桐花树生物动力地貌过程研究

桐花树作为红树林种群的先锋植物，其发育扩展和立地潮滩地貌变化的耦合过程是红树林生物动力地貌及生态修复研究关注的核心内容之一。本文基于2005?2019年高分辨率遥感影像、2019年10月至2020年10月的桐花树潮滩逐月沉沙量及其种群样方统计等资料，分析桐花树在南流江河口潮滩的变化特征及其与桐花树种群扩张的耦合机制。结果表明:(1)南流江河口堤外潮滩是桐花树种群的主要立地区，成年、幼年及胚胎桐花树呈带状依次出现在高潮滩、中潮滩及平均海平面附近。以平均海平面为基面，南流江河口高程为0.07 m的潮滩为桐花树一年生幼苗生长极限位置；(2)南流江河口桐花树自西北向东南快速向海扩张的格局与潮滩向海淤积前展维持一致，潮滩滩位升高成为宜林滩地是桐花树向海扩张的基础；(3)桐花树种群的消浪作用减缓水动力强度，促进泥沙在潮滩沉积，由此加速潮滩发育；低潮滩淤涨为中潮滩、高潮滩，为桐花树种群扩张提供立地条件，促进种群发育扩张。

Research on bio-morphodynamic processes of Aegiceras corniculatum in the Nanliu River Estuary

Aegiceras corniculatum is one of the pioneering mangroves. The coupling process involving A. corniculatum development and tidal flat geomorphological evolution is one of the core contents of mangrove bio-morphodynamic and ecological restoration research. Based on high-resolution remote sensing images between 2005?2019, monthly sediment and A. corniculatum population samples from October 2019 to October 2020, the variation characteristics of A. corniculatum distributed over the tidal flat of the Nanliu River Estuary were analyzed. Meanwhile, the coupling mechanism between the morphological changes of tidal flat erosion/accretion and the population expansion of A. corniculatum was discerned. The main results can be shown as follows: (1) it is found that the main grown area of A. corniculatum is the outer sides of the levees of Nanliu River Estuary. The distribution of the adult, youth and embryos of A. corniculatum presented bandy features along the high tidal flat, middle tidal flat and the area near mean sea level, respectively. Furtherly, tidal flat elevation of 0.07 m above the mean sea level is the growth limit of annual seedling. (2) A. corniculatum of the Nanliu River Estuarine flat expanded rapidly from northwest to southeast, which is in coincidence with development tendency of tidal flat. Tidal flat height is elevated with possibility for mangrove habitation, which should be necessary for A. corniculatum promoted seaward progradation. (3) A. corniculatum that induced wave attenuation can mitigate hydrodynamics forcing with benefit to tidal flat sedimentation, which can furtherly have tidal flat accreted seaward. Moreover, the low tidal flat can be elevated into the middle-high tidal flat by silting, which provides growth and development conditions for A. corniculatum.