Growth and Community Composition of Submerged Macrophytes in Lake Taihu (China): Assessment of Changes in Response to Sediment Characteristics

The aim of this study was to investigate variation in biomass allocation and community composition of submerged macrophytes to elucidate the effect of sediment depth on the growth and species diversity of submerged macrophytes. Field investigations were conducted in 36 sampling sites located across Lake Taihu, China; six plant species were found and communities were dominated by Potamogeton malaianus and Vallisneria natans. The results showed that the plant–sediment distribution relationship was supported by a biological trait (biomass index) and a strong predictive power of sediment depth to plant biomass, and the occurrence selectivity of submerged macrophytes toward relatively firm bottoms could be demonstrated along the eastern shore. Root and stem biomass were strongly positively correlated to sediment depth over a range from 0.1 to 0.25 m (p < 0.01), and approximately 0.25 m could be regarded as an upper limit for depth effect on the growth of submerged macrophytes. The results also demonstrated that species varied in their responses to sediment conditions, which influenced the community composition of submerged macrophytes. The observed pattern suggests the effect of sediment on growth and community composition is an important aspect restricting the restoration of submerged macrophytes.