Variations in ecosystem services in response to paddy expansion in the Sanjiang Plain, Northeast China

The ecosystem of the Sanjiang Plain in China has dramatically changed in the past four decades. This study investigated the history of paddy field expansion in the Sanjiang Plain and discovered the ecosystem service variations in response to paddy expansion. Integrating a series of Landsat images, we obtained the paddy expansion history from 1976 to 2015. Then, we calculated ecosystem service values (ESVs) to estimate the ecosystem service variations caused by paddy expansion in the Sanjiang Plain. The results indicate that the paddy area increased from 404,789-2,598,449 ha during 1976-2015, leading to a decline in the total ecosystem service values by 11288.04 million dollars. The largest decline in ESVs in response to paddy expansion was caused by wetland reclamation (9998.54 million dollars). Apart from agricultural products and gas regulation functions, the ESVs provided by other functions all showed a declining trend. Paddy expansion in the Sanjiang Plain increased agricultural product function at the expense of the decline of other functions. In future management practices, the rational allocation of water resources and paddy distribution are necessary in order to achieve sustainable development of both water resources and agricultural production. Some suggestions including coculture systems, restoring habitats for aquatic species, farm management that fosters biodiversity in paddy fields are provided for future sustainability.