Concept, theory and practice of near-natural wetland ecological restoration

With the increasing recognition of the importance of wetlands, the demand for wetland ecological restoration techniques is increasing in China, among which near-natural wetland restoration method has attracted more and more attention. The history of the development of near-natural method was reviewed. The definition of near-natural wetland was put forward, and the main differences between near-natural wetland and constructed wetland were analyzed. The ecological restoration of Zhushanhu wetland in Taihu Lake was used as an example to illustrate the design process, main technical measures and restoration effects of near-natural ecological restoration. In the near-natural ecological restoration of Zhushanhu wetland, measures such as the improvement of hydrological and hydrodynamic conditions, the construction of basement forms, plant restoration, aquatic animal restoration, and biomass and species management were successively implemented. The connectivity and mobility of water bodies were improved, the habitat diversity and suitability were enhanced. The wave style basal morphology was constructed based on five types of basement morphology. According to the principles of suitable habitat, priority of water purification and consideration of landscape, 35 species of indigenous wetland plants from 21 genera were selected, and two plant configuration models were designed and used in Zhushanhu wetland restoration process. Based on the analysis results of Ecopath with Ecosim (EwE) model on the structure of wetland food web, some suggestions were put forward on regulating the harvest of aquatic plants and the population number of shrimps, crabs and fishes. After ecological restoration, the water quality of Zhushanhu wetland was improved from below Class Ⅴ to Class Ⅱ of Environmental Quality Standards for Surface Water (GB 3838-2002), and the diversity of large aquatic plants increased significantly. The ecological restoration effect of Zhushanhu wetland has proved the effectiveness of near-natural ecological restoration methods. In the future, it is necessary to continuously enrich the theory and technology of near-natural ecological restoration in practice and carry out large-scale practical applications.