1. Resource allocation, including biomass allocation and nutrient allocation between different organs in a plant, reflects the trade-off in partitioning between aboveground and belowground organs and the growth and adaptation strategies of plants in a changing environment. Although varied resource allocation patterns among different organs in different functional groups of terrestrial plants have been found, few studies have focused on freshwater ecosystems.

2. In this study, to clarify biomass and nutrient allocation strategies and their responses to environmental factors, we collected and analysed 2162 samples from 262 aquatic plant communities (including emergent plants, floating-leaved plants and submerged plants) in various aquatic habitats in northeastern China.

3. The results showed that the root/shoot (R/S) ratios of the three aquatic plant life forms were significantly different, and the trend showed that the ratio values for the three plant life forms occurred in the following order: emergent plants > floating-leaved plants > submerged plants. There were obvious scaling relationships between aboveground biomass, N (or P or N:P ratios) and belowground biomass, N (or P or N:P ratios), but their scaling exponents changed among different aquatic plant life forms. The allocation of biomass and nutrients between different organ responses to environmental factors was not consistent for the different life forms of aquatic plants. The partial least squares path model revealed that plant stoichiometric characteristics are important direct drivers of biomass production. Climate conditions, water properties and soil nutrients indirectly affect biomass through effects on plant stoichiometric characteristics.

4. Synthesis: Our study demonstrates that global climate change may affect water properties and soil nutrients, influence plant stoichiometric characteristics and affect aquatic plant growth, further altering aquatic plant community structure and biogeochemical cycles.