Plastic response of resource allocation strategy and functional traits of an endemic submerged macrophyte (Ottelia acuminata) in the Erhai Lake.

Submerged macrophytes play a crucial role in lake ecosystems, and their survival is dependent upon their ability to cope with variable environmental stress. Therefore, studying the plastic response of submerged macrophytes' resource allocation and functional traits to the environment may provide insights helpful for ecological restoration practices. In September 2021, a field survey was conducted in the Erhai Lake, where samples of Ottelia acuminata, and functional traits and biomass allocation in relation to water depth were measured. The study found that O. acuminata exhibited large intraspecific variations to adapt to environmental stress, and the average intraspecific variation was 55.86%. In the current environment, this study suggested that the optimal growth depth for O. acuminata is moderate water depth (1-2 m). The results of allometric growth analysis showed that the resource allocation of O. acuminata responded to the water depth with the synergistic effect of leaf area and shoot height. In shallow water, the resource allocation of O. acuminata was mainly used for leaf area growth, while in deep water, the increase of shoot height was mainly used to cope with stress. This research will provide us useful information for the ecological restoration and protection of this endemic and endangered submerged macrophyte.