Spatial and Temporal Heterogeneity of Flooding Characteristics of Floodplain Lake Wetlands and Impact on Wetland Vegetation

Abstract

Flooding characteristics are important ecohydrological indicators of floodplain lake wetlands. They have a critical impact on the growth and distribution patterns of wetland vegetation. The Poyang Lake, which is the largest freshwater lake in China, is a typical floodplain lake wetland. This paper presents a hydrodynamic model of the Poyang Lake, analyzes the spatial and temporal heterogeneity of flooding characteristics (flooding duration and flooding depth), examines the impact of the Poyang Lake Water Conservancy Hub on flooding characteristics, and analyzes the response patterns of wetland vegetation concerning flooding characteristics. The results show that (1) the flooding characteristics of Poyang Lake have significant spatial heterogeneity, and that the lake can be divided into annual flooding area, annual waterless area, and alternating wet and dry area; (2) owing to factors such as climate change and human activities, the flooding characteristics of Poyang Lake have changed significantly since 2003. The average flooding duration is reduced by 15 days and the average flooding depth is decreased by 0.32 m; (3) the water level of Poyang Lake may be raised by the Poyang Lake Water Conservancy Hub in the future, and this may result in a further increase in the flooding duration and flooding depth of Poyang Lake; (4) the response relationship between the distribution area of five types of dominant wetland vegetation and flooding characteristics is consistent with Gaussian curve, and each type of vegetation has optimal flooding duration and depth. The flooding characteristics have a direct significant impact on the vegetation succession in Poyang Lake. The outcomes of the study provide a detailed understanding of the spatial and temporal heterogeneity of flooding characteristics and the drivers of wetland vegetation distribution patterns in floodplain lake wetlands, and they can provide scientific support for the conservation and restoration of floodplain lake wetland ecosystems.

Keywords: lake wetland, flooding duration, flooding depth, wetland vegetation, Poyang Lake