关键词: 土地利用变化, 景观连通性, 海滨湿地, 盐城

Abstract:

Land use and land cover change have been strongly affecting the function and structure of landscape ecosystem. Landscape pattern aims to build some optimized landscape which could make landscape eco-efficiency maximize and stabilize. Therefore, in this paper, the Yancheng coast is chosen as a study area and the technologies of remote sensing (RS) and geographical information system (GIS) are applied. Meanwhile, the valuation of wetlands landscape ecosystem services are used to analyze the landscape pattern. Based on ecological processes and resistance model, some proposals were put forward to optimize the wetlands landscape pattern. The results show: 1) The land use structure in the coastal zone of Yancheng has undergone significant change from 1987 to 2007. It is demonstrated that the percentage of farmland area ascends from 36.72 to 46.17, and the percentage of artificial wetland area ascends from 9.96 to 18.72,while that of natural wetland area declines from 44.4 to 26.01. 2) With more land use activities, the intensity of human disturbance to land increased from 1987 to 2007. A series of landscape ecological problems were caused by the increase of human disturbance to land, such as landscape shape complexity, low landscape ecological connectivity and more serious fragmentation of natural wetlands landscape. As a result of landscape ecological connectivity, function and the ecological process, such as energy flow in a landscape was declined. Ecological process and functions of wetlands in the coastal area were different in spatial distribution in 2007. The total value of ecosystem services is 77.09 billion yuan/a. The rate of contribution to the reed marsh, Saline seepweed marsh and Spartina alterniflora marsh is the highest, accounting for 86.91% of the total value, and they are mainly distributed between Sheyang Estuary and Doulong Port, and secondly distributed to south of Doulong Port, while the mud flat, paddy field and aquiculture pond is lower. 3) Based on an accumulative cost distance model, the calculation of the cost distance, and identification of the sources, the critical ecological positions, corridors, and sources were designed in the study area, and the landscape pattern optimization further discussed, such as protecting of nature resources, constructing the buffer region, rehabilitating suitable vegetation types to improve connectivity of landscape. 4) Optimization of wetlands landscape pattern improved flow and connectivity of landscape. The critical ecological positions for flow and connectivity of landscape close to the bays of the Old Huanghe River estuary and Dafeng Port was most important, and it was the primary object to be optimized. 5) According to the principles of landscape ecology, the key to optimize the landscape pattern is to strengthen protection of nature sources, and maintain high landscape connectivity in Yancheng coastal zone so as to realize the objectives of sustainable development in land-use and environmental protection.

Key words: land-use change, landscape connectivity, coastal wetlands, Yancheng