Landscape ecological risk assessment of chongming dongtan wetland in shanghai from 1990 to 2020

Landscape ecological risk assessment can assess the stability, vulnerability, and anti-interference ability of the ecosystem based on the characteristics, structure, and function of the landscape in order to determine the degree and distribution of landscape ecological risk. In recent years, due to human activities and global climate change, the area and ecological quality of the Chongming Dongtan wetland have been decreasing. As an important wintering habitat and transit point on the 'East Asia-Australia migration line', the population and habitat security of wintering migratory birds are also threatened. Therefore, the landscape index method was used to assess the ecological risk of the Chongming Dongtan wetland. Based on transfer analysis and spatial autocorrelation analysis, the spatial and temporal changes of landscape ecological risk were revealed. The findings are as follows: (1) Natural landscapes such as mudflats, grasslands, and waters have been declining, while artificial landscapes such as cultivated land, construction land, and woodland have been gradually expanding, indicating a shift from natural to artificial landscapes. (2) Overall, the landscape ecological risk is showing an increasing trend. Wetlands have moved from being dominated by the lowest and medium ecological risks to being evenly distributed by all ecological risk classes. Notably, there has been a rapid increase in landscape ecological risk in 2000. The highest-risk areas have expanded by 9346.95 hm2, gradually encroaching from the buffer zone into the reclamation area and the nature reserve. Conversely, the lowest ecological risk areas have decreased by 7091.82 hm2, primarily concentrated in nature reserves. (3) The aggregation of landscape ecological risks continues to decrease, indicating a reduced likelihood of dramatic changes in ecological risks.