| Coastal wetland is the important environmental resources, with important ecological functions and social values, which is one of the richest bio-diversity on the earth. Beach is one of the most important natural resources in coastal zone, is also considered as important part of coastal wetland. In recent years, with the development of social economy and the urgent demand for land, the landscape pattern of coastal wetland has changed enormously under the disturbance of human reclamation activities, which presents that natural wetland was converted to artificial wetland. To investigate the impact of reclamation on the landscape pattern of coastal wetlands in Yancheng, northern Jiangsu of China, RS, GIS and FRAGSTATS technologies were applied to analyze the remote sensing data from 1973 to 2013 as basic information resource. Changes of landscape between reclaimed and unreclaimed zones in the national nature reserve of Yancheng, were compared and analyzed from Chuandong Port to Xinyang Port. Haifeng, Haibei and Jinfeng reclamation were selected from reclamation zones, and then landscape pattern changes of each reclamation in the same stage of reclamation were also compared and analyzed. It is of great theoretic and practical significance to the rational use of costal wetland resource, wetland function preservation, ecological and social development.Tideland reclamation led to the change of original landscape pattern directly in reclaimed zones, which was accompanied by the activity of reclamation. With Haifeng, Haibei and Jinfeng reclamation, for example, the changes of each reclamation were not completely consistent in different stage of reclamation. The main conclusions are as follows:(1)The natural landscape was progressively transformed into artificial landscape in Haifeng, Haibei and Jinfeng reclamation; The patch shape tended to be more simple or regular in Haifeng, Haibei, while more complex and natural in Jinfeng. Meanwhile, the changes of fragmentation were distinctive form each other that, the tend of each reclamation were "up-down-up", " down-up-down" and "up-down". (2) By contrasting landscape changes in different stage of reclamation with each reclamation, before reclamation, the differences between changes of landscape area and patch shape were neglectable, but were significant in the landscape fragmentation, due to the location away from the sea of specific reclamation influenced the vegetation distribution or diffusion. Landscape pattern changes were similar among Haifeng, Haibei and Jinfeng during the period of land reclamation, and that of each site maintained the condition at the end of reclamation, except in the presence of a new round of human disturbance.The core region of Yancheng national nature reserve area, which is strong protected by government, has been the natural unreclamation zone. Consequently, comparing the changes of landscape pattern between unreclamation zone and reclamation zones can directly showed the effects of reclamation to the changes of landscape pattern in the coastal wetland. The results indicated that:(1) In unreclamation zone, the natural landscape remained the dominant position in landscape structure with 84.6 percent in 2013.The wetland of Pragmites communis and Spartina spp. increased by 4 770.6 hm2 and 4 202.8 hm2 respectively, while the wetland of Saueda spp. decreased by 2 656.7 hm2. In reclamation zones, the massive original natural landscape types were converted to the artificial landscape types from 1984 to 2013, and artificial landscape held dominant position in landscape structure after 2000. The natural vegetation area continuously decreased except Spartina spp., while aquaculture pond area increased rapidly with 60.5 percent in 2013. (2) In unreclamation zone, the fragmentation remained low level (from 0.27 to 0.28) after 1995 because of the expansion of Pragmites communis and Spartina spp. patches, and the patch shape trended to be complex or irregular, while landscape diversity increased by 0.19 from 1984 to 2013. On the contrary, in reclamation zones, the degree of fragmentation significantly increased by 0.27, and the patch shape trended to be simple or regular, while landscape diversity decreased by 0.26 from 1984 to 2013, because of the rising dominance of Aquacultural ponds. (3) Landscape type centroids movement in unreclamation zone had the characteristics of continuity and clearly direction, as the main driving mechanism of landscape pattern was natural factors. Conversely, landscape type centroids movement in reclamation zones had the characteristics of disorder, variedly and intricately with the intervention of human activities. |
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