A research team led by Prof. Xie Yonghong from the Institute of Subtropical Agriculture, Chinese Academy of Sciences, has provided new insights into the competitive mechanisms shaping aquatic plant communities in eutrophic shallow-water ecosystems.

Their recently study, published in Freshwater Biology，reveals that competition between floating-leaved and submerged plants, as well as among submerged species, is jointly regulated by environmental conditions and plant functional traits.

As a critical role in maintaining ecosystem stability, aquatic vegetation, is central to the restoration of eutrophic lakes. However, the competitive dynamics underlying community assembly—particularly between different plant life forms and among submerged species—remain insufficiently understood. Understanding how key environmental drivers such as nutrient availability and light interact with plant growth strategies is essential for designing effective restoration practices.

To address this challenge, the research team conducted two controlled experiments under eutrophic conditions. The first experiment examined competition between floating-leaved plants and submerged macrophytes with contrasting growth forms. The floating-leaved species Nymphoides peltata was grown with three typical submerged plants: the basal rosette-type Vallisneria natans, the erect-type Myriophyllum spicatum, and the canopy-forming Myriophyllum verticillatum. A mesocosm experiment was established with three floating-leaved plant densities and three nutrient levels.

Results showed that the competitive suppression exerted by floating-leaved plants was both density-dependent and species-specific. Medium and high densities of N. peltata significantly reduced the biomass and chlorophyll content of all submerged species. However, the negative effects on plant morphology were much stronger for V. natans and M. verticillatum than for M. spicatum. While higher nutrient levels partially mitigated competition at moderate floating-leaved density, they also enhanced the dominance of erect and canopy-forming submerged plants, indicating that eutrophication may favor floating-leaved plants and drive submerged communities toward a few tolerant species.

The second experiment focused on competition between submerged plants by comparing V. natans and M. spicatum under varying nutrient and light conditions using a replacement-series design. The study found that interactions between light and nutrients were decisive in determining competitive outcomes. M. spicatum dominated under high-light and high-nutrient conditions through rapid biomass accumulation, whereas V. natans performed better under low-light and low-nutrient environments by adopting a more conservative growth strategy. Differences in morphological plasticity further contributed to shifts in competitive advantage along environmental gradients.

“Our results show that competitive outcomes among aquatic plants are highly context-dependent,” said Prof. Li Feng, the corresponding author of the study. “Environmental factors such as nutrients, light availability, and floating-leaved plant cover interact strongly with plant growth forms and adaptive strategies. Recognizing these interactions is crucial for developing more precise and sustainable vegetation restoration approaches in eutrophic lakes.”

Contacted: Feng Li

E-mail: Lifeng@isa.ac.cn

Changes in plant nutrient content and relative competitiveness index under different treatments (Image by Chuanxin Chao and Weicheng Yu)