The Spatial-temporal Changes of the Ecosystem Service Value by Land Use and Land Cover Change in Circum-Taihu Lake region

Based on the data of multi-temporal point TM images, by applying the theory of Ecosystem Service Value, the Gravity Center Model, ESDA method and so on, the paper calculates the ecosystem service value in Circum-Taihu Lake region in 1985, 1995, 2000, 2005 and analyzes the characteristics of the gain and loss of the ecosystem service value, their spatial difference changes, the spatial pattern evolution and the temporal-spatial mechanism of the ecosystem service value by land use change in Circum-Taihu Lake region during 20 years. The results are as follows: 1) the ecosystem service value in Circum-Taihu Lake region in recent 20 years has decreased 0.81 billion yuan with yearly decrease of 0.04 billion yuan and the decreasing speed in recent 10 years has slowed down a little. The great decrease in arable land chiefly accounts for the decrease in ecosystem service value; 2) the profits and losses of the ecosystem service value is quite varied in different places, the ecosystem service value in the entire area has been on the decline and that of some local areas has been falling faster and faster; 3) the gravity center of the ecosystem service value in Circum-Taihu Lake region is gradually moving southwestward. The spatial difference of the ecosystem service value in different regions tends to decrease. The decreasing speed in E-W direction is faster than that in S-N direction. The spatial difference changes are chiefly due to the spatial difference changes of arable land and water area; 4) The whole spatial pattern of the ecosystem service value in Circum-Taihu Lake region remains relatively stable; however, it shows the spatial autocorrelation. areas similar in land capita ecosystem service value in Circum-Taihu Lake region tend to cluster, that is, areas with high or low land capita ecosystem service value cluster respectively in space. This trend is becoming stronger with the passage of time. The changes of the spatial pattern of ecosystem service value are mainly driven by the evolution of the spatial pattern of arable land.