Rapid urbanization negatively affects landscape, ecological connectivity, and biodiversity of wetland ecosystems worldwide, and the specific effect mechanisms need to be deeply explored. In the present study, we aimed to determine if and how rapid urbanization has affected the biodiversity and ecosystems of wetlands in Kunshan, which has ranked first among China's top 100 counties and cities in comprehensive strength for 20 years. We conducted field investigations in 11 towns of Kunshan, where we determined different water parameters and biodiversity indices in the wetlands of urban, middle, and natural regions as well as several urbanization indices. The results indicated an upward trend for the biodiversity indices, including density, biomass, species number, Shannon diversity, and Margalef richness of the aquatic plants and macrobenthos from the urban to middle to natural regions. Furthermore, the results indicated a downward trend for the water parameters, including salinity, total dissolved solids, pH, total phosphorus content, ammonia nitrogen content, and permanganate index from the urban to middle to natural regions. Overall, the biodiversity indices of aquatic organisms were negatively correlated with water parameters and urbanization indices, including population density, gross domestic product, number of industrial enterprises above the designated size, industrial energy consumption, and building construction area. Thus, the results demonstrate that rapid urbanization leads to habitat destruction and biodiversity reduction in aquatic plants and macrobenthos. This study provides scientific implications for management and restoration of urban wetlands during rapid urbanization, including water pollution control, ecological shoreline protection, ecological connectivity optimization, aquatic plants, and macrobenthos restoration.

Improving the zonal management of the ecosystem service (ES) supply-demand balance requires a thorough understanding of its spatiotemporal variability and the nonlinear characteristics of the driving mechanisms. Coordinated social-ecological development at the regional level depends on this understanding. Consequently, we delineated bundles of the ES supply-demand relationship within the Harbin-Changchun urban agglomeration, examined interactions between ES supply and demand across these bundles, and investigated the mechanisms by which social-ecological drivers shape the spatial pattern of this relationship over an extended time series. The findings show that deficit areas for the 5 ESs are concentrated in construction zones and have expanded annually; synergies outweigh trade-offs among the 5 bundles, and the trade-off relationship intensifies markedly over time. Social drivers dominate bundles 1 (key synergetic bundle), 2 (carbon fixation-water yield-crop production synergetic bundle), and 5 (carbon fixation-crop production-habitat quality synergetic bundle), whereas ecological drivers prevail in bundles 3 (water yield bundle) and 4 (ecological transition bundle). The ES supply-demand relationship is increasingly strained by social disturbances over time. A normalized value near 0.5 emerges as a recurrent threshold at which the effects of several metrics such as digital elevation model, average precipitation, and normalized difference vegetation index shift over a 20-year period. Implementing precise optimization and rational planning for bundle-level ecological management benefits sustainable development and human well-being.

Integrating ecosystem services (ESs) into ecological security patterns (ESPs) provides a comprehensive framework for recognizing critical conservation areas and enhancing regional ecological security. However, previous studies are predominantly based on ES supply, while often not fully considering the supply-demand balance and its dynamic trends. This study proposed a comprehensive framework including comprehensive supply-demand ratio (CSDR), CSDR trend, total supply trend, and trade-off to revise ecological source recognition. Subsequently, ecological resistance surfaces were revised using land use and nighttime light data. Finally, corridors and strategic nodes were further recognized according to circuit theory to establish a comprehensive ESP. Selecting Three Gorges Reservoir Area as a research case, the results show that the ecological sources (18,232.59 km²) are predominantly situated in the eastern regions and parts of the southern bank of the Yangtze River with high supply and low ecological risks and trade-off levels. The low value of the resistance surfaces is distributed consistently with ecological sources, and the high value of the resistance surfaces is distributed near the cities with high population density and demand. Two hundred sixty-six key ecological corridors and 195 pinch points connected the regions into an organic whole and barrier points, with an area of 285.96 km² overlapping with the potential corridors. These findings offer guidance for regional planning and sustainable development.

Terricolous mosses and epilithic mosses are often used to indicate atmospheric nitrogen (N) deposition, while terricolous mosses also absorb N from soils. How to use N isotopes (δ¹⁵N) of terricolous mosses to trace the levels and sources of atmospheric N deposition accurately is an urgent problem to resolve. Based on the N contents (N_moss) and isotopes (δ¹⁵N_moss) of terricolous and epilithic mosses collected in Mount Qilian in 2022, we established a bottom-up method to calculate local atmospheric N deposition levels and source contributions. No significant difference was found in N_moss between soils and bare rocks, whil terricolous mosses had significantly higher δ¹⁵N_moss than epilithic mosses. Thus, the effects of soil N sources on δ¹⁵N_moss of terricolous mosses should be excluded before they are used to tuace emission surrces of atmospheric N deposition. The flux of total inorganic N deposition in Mount Qilian was 15.0 ± 2.3 kg N ha⁻¹ year⁻¹, with nitrate-N deposition being dominant. According to analyses of emission sources, it was volatilization-related ammonia (61.9% ± 19.8%; mainly from fertilizer application and wastes) rather than combustion-related ammonia (38.1% ± 19.8%) that dominated atmospheric ammonium-N deposition. It was fossil fuel N oxides (51.5% ± 19.6%; mainly from oil and coal combustion) rather than non-fossil fuel N oxides (48.5% ± 19.6%; mainly from biomass burning and microbial N cycles) that dominated nitrate-N deposition in this region. The Mount Qilian region holds an important position as a crucial ecological barrier in western China. Therefore, it is important to reduce reactive N emissions based on the above source apportionments to protect the fragile ecosystems of Mount Qilian.