2． Northeast Institute of Geography and Agricultural Ecology，Chinese Academy of Sciences，Changchun 130102，China

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．