Evolution characteristics of hydrological connectivity pattern of marsh wetland in Naoli River Basin

As an important indicator of the structural and functional stability of wetland landscapes, hydrological connectivity plays an important role in maintaining the stability of wetland ecosystems. Large-scale human activities have led to significant changes in the hydrological connectivity pattern of wetlands in Naoli River Basin since 1950s. Combined with the availability of wetland habitat and the spreading capacity of aquatic birds, hydrological connectivity indices of marsh wetlands were calculated in the studied area, and the temporal and spatial changes were analyzed from 1950s to 2015. The results indicate that: (1) the hydrological connectivity index of the marsh wetlands shows a growth trend with increasing distance threshold. All patches of marsh wetlands linked together when the distance threshold reached 35–40 km; (2) the optimal distance of hydrological connectivity is about 10 km for marsh wetlands of whole Naoli River Basin; (3) the total hydrological connectivity of marsh wetlands decreased in the Naoli River Basin from 1950s to 2015. Although the hydrological connectivity index increased after 2005, the fragmentation of the landscape has not been improved. The analysis of the wetland hydrological connectivity can provide a scientific basis for the ecological restoration and protection of the wetland in the Naoli River Basin.