Abstract: The expansion of road networks has resulted in the fragmentation of wetland landscapes, decreased connectivity and increased ecological risks, presenting a big challenge to wetland conservation and sustainable development in the ecologically fragile regions of the Qinghai-Tibet Plateau. Quantitative assessment of the impacts of roads on landscape patterns and ecological risks, as well as their spatial heterogeneity, is crucial to comprehending the effects of roads on wetlands. We investigated the quantitative relationships between the impacts of roads on the structure of different wetland landscapes and the associated ecological risks, along with their spatial-temporal variations from 1990 to 2020 in the Yangtze River Source Area within the Sanjiangyuan National Park on the Qinghai-Tibet Plateau. Data were analyzed with scenario analysis, spatial association, and geographically weighted regression. The results showed that: (1) Road expansion enlarged the differences of landscape structure of different wetland types. The most significant effects were observed in the patch density and landscape shape index of riparian wetlands, and the connectivity of salt marshes, while the impact on lakes was minimal. (2) Over the past three decades, road network density increased more rapidly in the southeast, mainly characterized by low-density growth centered around villages. The areas of wetland landscapes at high, relatively high, and moderate ecological risk levels showed a stepwise declining trend, with high-risk zones being concentrated in salt marshes, glacial wetlands, and the confluence of riverine and marshy wetlands. (3) Throughout the study period, the area primarily witnessed an increase in clusters of high road density and low ecological risk. These clusters were concentrated in areas with lower-grade roads, indicating that the addition of lower-grade roads did not significantly affect the ecological risk to wetland landscapes. Conversely, areas with high ecological risk and high road density were predominantly concentrated along the G109 highway. Wetland landscapes adjacent to higher-grade roads faced higher ecological risk. Moreover, in the central salt marsh and riparian wetland zones, road density exhibited a positive correlation with wetland landscape ecological risk, suggesting that the construction of higher-grade roads would enhance ecological risk to wetland landscapes. Our findings provide a scientific foundation to guide wetland conservation and road construction in the ecologically fragile regions of the Qinghai-Tibet Plateau.

Key words: wetland landscape, road network, ecological risk, spatial heterogeneity, Qinghai-Tibet Plateau