Assessment of impact on coastal wetland of Xiamen Bay and response of landscape pattern from human disturbance from 1989 to 2010

Selecting two key periods after the establishment of Xiamen Special Economic Zone as monitoring periods based on the remote sensing images from 1989 to 2010,we established a database containing wetland and non-wet-land landscapes in Xiamen Bay in 3 periods. With approaches of landscape ecology and geostatistics,human disturbance was analyzed and its dynamic model was set up to assess the influence of human disturbance on the coastal wetland and its dynamic changes in the past 22 years. Besides,the response process of landscape pattern was analyzed. The results presented that the coastal wetland of Xiamen Bay was continuously degenerating. The area of the natural wetland decreased from 275. 82 km2in 1989 to 238. 60 km2in 2010. The area of non-wetland rose from 590. 61 km2in 1989 to 637. 09 km2in 2010. In the different stages of urbanization,the coastal wetland had experienced transitions mainly from the process of constructed wetlands to the non-wetland. The degree of disturbance and its dynamic model efficiently characterized the spatial responding relations between urban spatial expansion and human disturbance. The influence of human disturbance was expanding in scale and intensity,and showed a tendency extending from the land to the sea. In the first period,the west coastline had been an important area of Xiamen urban spatial development,and the wetland resource was the important goals occupied by urbanization and sea farming. In the second period,the high value area of human disturbing variation had shifted from the west to the east of Xiamen Bay along the coastline formed a new disturbance zone. The mid-high value area of human disturbing variation had spread to the whole area studied. The coastal wetland resource space had been further squeezed. The high value area of dynamic change of disturbance degree showed the most significant degeneration of coastal wetland, where it could be the key area of wetland protection and ecological restoration in the future. The integration of edge density,plaque density and the degree of separation can efficiently reflect the responding relationship between landscape pattern information and human disturbance. The landscape pattern in the area studied tended to be complex, showing increasing degree of landscape heterogeneity and landscape fragmentation. Non-wetland landscape gradually dominated and the dominant landscape control of coastal wetland was weakened. Human disturbance has become the main driver in evolution of landscape pattern for the wetlands in coastal Xiamen Bay.