Ecosystem health assessment of the largest lake wetland in the Yellow River basin using an improved vigor-organization-resilience-services model

Abstract

Wuliangsu Lake is the largest lake wetland in the Yellow River basin, it is the Northern Sand Belt of China, which is essential to maintaining ecological security in northern China and the areas downstream. With the increasing environmental problems, the basin has become a sensitive and complex geographical unit, and a better understanding of the level of ecosystem health in the basin is helpful for policymakers in developing measures for ecological restoration and eco-space management. In this study, we proposed an improved VORS model containing ecosystem vigor, organization, resilience and services to assess the ecosystem health in the Wuliangsu Lake Basin in 2000, 2011, and 2022. To improve spatial precision, the study area was partitioned into grids measuring 2 km × 2 km each. The results indicated that: (1) the ecosystem health showed a slight increase trend, which indicated by the increase level grids reached 94 % in 2000–2022 change. (2) The reduction in vegetation cover decreased the ecosystem vigor, which was indicated by the weak level increased from 22 % in 2000 to 73 % in 2022. Ecosystem structure becomes more complex enhanced the ecosystem organization, the value increased from 0.3 to 0.6 in 2000 to 0.6–0.8 in 2022. Ecosystem resilience slightly declined in 2011 and 2022, ecosystem services were relatively stable but were dominated by weak levels. (3) The majority land use type in the study area is farmland, and the ecosystem vigor decreases as the area of grassland decreases to farmland in these 22 years. The ecosystem’s structure was enhanced and the land use structure was progressively brought into balance. Changes in all four parameters of ecosystem health assessment are related to land use, and changes in ecosystem health are likewise related to land use changes. The improved VORS model constructed for the Wuliangsu Lake Basin objectively reflect the basin’s state of ecosystem health, and provide a reference for ecological restoration and basin regional planning.