Characterizing the spatial pattern of marshlands in the Sanjiang Plain, Northeast China

Over the past three decades, the marshlands in Northeast China's Sanjiang Plain have undergone dramatic loss and fragmentation. This study has analyzed the loss area and pattern of these marshlands for the period 1982-2010 using remote sensing data. The marshlands area decreased 786.69 × 103 ha until 2010. The landscape pattern changes of the marshlands and other land use types were analyzed spatiotemporally for the years of 1982, 2000 and 2010. Results showed that during the period from 1982 to 2010, the gravity center of marshlands migrated 0.2170° southward, then again 0.0848° eastward, moving it a total of 25002.59 m. Spatial distribution of the marshlands continually migrated southeastward which was influenced by the landscape characteristics, such as the location of the marshlands in the watershed, geomorphology, and anthropogenic/natural causes, such as the intensity of agricultural development, population and climatic change. The southern and northern marshlands loss rates were very different between 1982-2000 and 2000-2010. The reclamation intensity of cultivated regions in central parts inclined to north of the Sanjiang Plain had been strengthened again, and the reclamation ratio changed from less than 0.5 to nearly 0.8 even to 1 when comparing 1982-2000 with 2000-2010. Increasing air temperature would otherwise have enhanced grain yields and stimulated marshlands conversion into croplands.