Wetland landscape pattern changes over a period of rapid development (1985-2015) in the ZhouShan Islands of Zhejiang province, China

Landscape dynamics of wetland are critical for understanding coastal ecosystem health and sustainability. The paper characterizes the spatiotemporal dynamics of the wetland landscape in the Zhoushan Islands during 1985-2015 to reveal the spatially explicit influential indicators. Wetland distribution in four periods (1985, 1995, 2005 and 2015) was derived from Landsat Images via artificial visual interpretation and support vector machine. Landscape pattern indices were then used to quantify landscape changes and statistical data was employed to identify the drivers. During 1985-2015, the total area of the Zhoushan Islands had been increased from 1277.15 km2 in 1985 to 1368.12 km2, and the total area of wetlands gradually increased from 123.31 km2 to 195.88 km2. The two-subtype wetlands presented opposite trends: the natural wetland decreased from 68.15 km2 to 62.08 km2 while the artificial wetland increased from 55.16 km2 to 133.80 km2. Since 1995, the area of artificial wetlands has exceeded that of natural wetlands. Moreover, natural wetland gradually became fragmented. The dominant transition of wetland types in the Zhoushan Islands was from natural wetlands to artificial wetlands. Moreover, some other transitions include artificial wetlands transferred to non-wetlands and new reclamation lands from the ocean transferred to construction and aquaculture lands were also identified. The wetland landscape pattern changes were not only affected by natural and socioeconomic factors, but also influenced by urbanization level and reclamation projects. Furthermore, the increasing artificial wetlands also played an important role in protecting the local ecological environment.