Study On The Change Of Vegetation Coverage And Landscape Pattern In Zhoushan Islands

Vegetation coverage is an important parameter for analyzing the status of vegetation. The research on the changes of vegetation coverage is of important theoretical significance and application value for a study area in terms of analyzing the vegetation change and exploring the impact factors.By means of the methods of remote sensing and GIS, the change of landscape pattern and vegetation coverage in Zhoushan Islands were studied. The distribution of NDVI along islands were calculated and analyzed, and based on the method of dimidiate pixel model and the TM/ETM+ images of 1987 and 2005, the vegetation coverages in Zhoushan islands were estimated. Contrasting the distribution of these two years, the variation laws of the vegetation coverages of the main islands were analyzed. Then, the vegetation coverages were classified, and the distribution pattern of different classes were studied. The area effect and the distance effect influencing on the change of vegetation coverage in Zhoushan Islands were studied relating to the theories of island biogeography and meta-community.Vegetation coverages in Zhoushan Islands declined from 1987 to 2005. Relating to the factors such as island areas and the distances from islands to mainland, the landscape and vegetation pattern of Zhoushan Islands were further studied, showing that due to various factors including the edge effect, the islands with smaller areas tended to have serious fragmentation. The islands with medium distance to the mainlands tended to have most serious fragmentation. With the decrease of the areas of islands, the landscape connection level increased. When the islands become more isolated, the distribution pattern of discrete islands tended to be more balanced, and the patches in smaller islands tended to have evener probability of neighboring to other type of patches in the islands. Whereas, with the increase of the distances of islands to the mainlands, the probability of the patches in islands with higher level of vegetation coverage neighboring to other type of patches in the islands tended to decrease.