The basin along the Yangtze River in Anhui Province is an important ecological protective screen in the Yangtze River Delta Economic Belt, with a large number of wetlands, lakes, and nature reserves in the basin. The effect of the rapid development of regional urbanization on the ecological environment quality has become an important threat source that restricts ecosystem function and biodiversity protection in the basin. Therefore, this study used InVEST model to analyze the spatial and temporal evolution of habitat quality based on remote sensing image data from 1990, 2000, 2010, and 2020 in the basin along the Yangtze River in Anhui Province and revealed the spatial evolution trend of habitat quality degradation by using hot and cold spot analysis methods. The geographical detector model was used to discuss the main driving factors of habitat quality change. The study results showed that a trend of increase and decrease of construction land and paddy land in the basin from 1990 to 2020 was the opposite, that is, the area of construction land increased, and the area of paddy land decreased. Especially, the area of construction land increased from 390.18 km² in 1990 to 1616.34 km² in 2020. The area of increase and decrease of other land types remained around 1% to 2%. During the period from 2000 to 2020, Construction land was mainly transferred in from paddy land, accounting for over 60% of the area transferred in, which indicated the continuous increase of human activity intensity in the study area. From 1990 to 2020, the areas with a significant decline in habitat quality in the basin were mainly concentrated along the Yangtze River and in the northern part of the Chaohu Lake. The area proportion with the lowest grade of habitat quality showed a trend of increasing year by year, that is, the area proportion increased from 4.85% in 1990 to 8.47% in 2020. The hot spots of habitat quality degradation were concentrated in Hefei and its surrounding areas, while the cold spots of the degradation were mainly concentrated in the southern and western mountainous areas. Land use type was the main driving factor affecting habitat quality, and the interaction between land use and per capita GDP was the main driving factor for changes in habitat quality. The study results had important theoretical and practical value for the ecological environment protection and harmonious development of the relationship between humans and nature in the basin along the Yangtze River in Anhui Province.

Coastal wetlands in China provide important stopover sites for migratory shorebird species. The loss of natural wetlands caused by land reclamation over the past few decades poses a major threat to shorebird populations. Although habitat loss at key stopover sites has been shown to lead to reductions in shorebird populations, the effects of habitat loss at specific stopover sites on shorebird populations remain unclear. Here, we used shorebird diversity indices and landscape metrics to elucidate the long-term (19952020) effects of habitat change on shorebird community structure in the Yellow River Delta, which is an important stopover site for shorebirds along the Yellow Sea coast. The results showed that the habitat area, largest patch index, mean patch area, and the aggregation index decreased over 25 years. By contrast, the number of patches and patch density increased over the same period. The richness, Shannon-Wiener index, Pielou index, and Simpson index of the shorebird community increased from 1995 to 2020, while abundance of shorebird declined by 90.14%. Declines in the abundance of species were more pronounced in larger-bodied ones than in smaller-bodied species (T=1.156, df=42, p=0.02). On the other hand, there were no significant differences in the decline in the abundance of threatened species and non-threatened species (T=-0.483, df=42, p=0.632) and coastal specialist species and generalist/inland specialist species (T=-1.197, df=42, p=0.239). The decrease in mean patch area significantly contributed to the reduction in abundance of shorebirds (N=6, p=0.01), and its effects were more pronounced on larger-bodied ones than on smaller-bodied species (T=-2.113, df=42, p=0.04). These results suggest that habitat loss in the Yellow River Delta has contributed to declines in shorebird populations and that larger-bodied ones are more sensitive to habitat change than smaller-bodied species. Existing wetlands are in urgent need of conservation, and further land reclamation in this region should be avoided. In addition, the development of conservation plans for coastal wetlands requires consideration of variation in the responses of different functional groups to habitat change.

Poyang Lake wetland in the middle and lower Yangtze River floodplain provides important wintering sites for migratory waterbirds. Extreme climatic events and human activities have resulted in the degradation and redistribution of habitat over the last few decades. However, the effects of habitat changes on the abundance of waterbirds remain unclear. We used long-term waterbird monitoring data and Landsat remote-sensing data to characterize changes in abundance and the relationship between habitat variation and abundance. A total of 113 waterbird species were recorded in the wintering period between 1999 and 2021, including 23 globally threatened species. Greater White-fronted Goose (Anser albifrons), Swan Goose (Anser cygnoides), Bean Goose (Anser fabalis), and Tundra Swan (Cygnus columbianus) were the dominant species. A total of 46 species with more than 6 annual surveys and average abundance >100 were recorded between 1999 and 2021. For most species, the mean abundance across all sub-lakes was higher in the first year than in the last year, and no obvious changes were observed over the last 20 years. The mean abundances of the vulnerable species Hooded Crane (Grus monacha) and White-naped Crane (Grus vipio) significantly declined between 1999 and 2021. No significant changes in the mean abundance of all foraging groups were observed. The area of water bodies increased, and the area of mudflats decreased. For most species with significant changes in abundance, habitat change did not greatly contribute to variation in mean abundance. The reduction in the area of mudflats greatly contributed to declines in the mean abundance of the gray heron (Ardea cinerea) and gadwall (Anas strepera).