Evaluation of ecological reconstruction effectiveness of landscape lakes based on Ecopath model

To evaluate the effectiveness of freshwater-based ecological restoration measures employed in a landscape lake in the Southwest region of China and explore potential human interventions to enhance the restoration outcomes, a study was conducted using ecological survey data collected three years after the lake restoration project. As per the essence of the survey findings, an Ecopath model was constructed for the landscape lake, enabling an analysis of the variations in water quality, the newly formed structure of the food web, the flow of energy among trophic levels, and the maturation and stability of the ecosystem after the transformation. The Ecopath model encompassed a total of 16 functional groups, including piscivorous fish, carp, crucian carp, silver carp, bream, herbivorous fish, zooplankton, phytoplankton, and submerged aquatic plants, covering the entire energy flow process within this ecosystem. The results indicated a P index of 0.546 for the landscape lake Ecopath model, demonstrating a substantial level of reliability. The trophic levels within the lake ecosystem ranged from 1 to 3.092, with an overall energy transfer efficiency of 1.648%, which was considered relatively low. The ratio of net primary production to total respiration (TPP/TR) was 1.946, the connectivity index (CI) was 0.280, the system omnivory index (SOI) was 0.052, and Finn's cycling index (FCI) and Finn's mean path length (FML) were 5.079% and 2.383, respectively. These figures showed a preliminary recovery of the food chain within the landscape lake compared to its pre-restoration state. By integrating the comprehensive analysis of the ecosystem connectivity model, it was revealed that the landscape lake exhibited characteristics of a relatively unstable, less connected food web, with limited resilience to external disturbances, suggesting an immature ecological system in its developmental stage. Therefore, future human intervention and regulation are still required for the freshwater-based ecosystem construction model to reach its full potential.