Rapid change of vegetation cover in the Huanghe (Yellow River) mouth wetland and its biogeomorphological feedbacks

Abstract

Vegetation plays a crucial role in the evolutionary process of coastal wetlands through its biogeomorphological feedbacks, and has become a hot topic of worldwide concern in the context of global climate change. However, as one of the youngest wetlands, the impact of vegetation expansion on the evolution of the Huanghe mouth wetland is currently unknown. In this study, we investigated the spatial and temporal variation of the vegetation cover in the Huanghe mouth wetland over the past twenty years and quantitatively examined its biogeomorphological feedbacks on the river mouth evolution. The results showed that the vegetation cover of the Huanghe mouth wetland has expanded rapidly since 2012 due to the invasion of the exotic species Spartina alterniflora. Its biogeomorphological feedbacks controlled the spatial distribution of surface sediments in the Huanghe mouth wetland and also altered the sediment budget in subaqueous and subaerial deltas. The land-building efficiency of the Huanghe sediment jumped to 101.76 km2/Gt, more than four times that of the pre-invasion period. Compared with other coastal wetlands in the world, the unique feature of high suspended sediment concentration (SSC) makes the Huanghe mouth wetland with high accretion rate under the influence of vegetation. The present study reveals the rapid changes of the vegetation cover and its biogeomorphological feedbacks in the Huanghe mouth wetland, and highlights that the vegetation plays a more critical role in the morphological evolution of the highly turbid river mouth.