The Spatiotemporal Evolution Analysis of Ecosystem Pattern in Wenchuan (Magnitude 8.0) Earthquake Disaster Area, China

The ecological system is the basis of human survival and global environmental protection. In the process of development, countries will pay close attention to the changing state of the ecosystem. Taking the ecosystem pattern as the research object, a three-layer analysis method was proposed. The transfer matrix and landscape index were used as the first layer to analyze the basic changes. Grey correlation, range-coupling coordination and relative priority were used as the second layer to analyze the reasons of the change. The interval-entropy weight, TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution), was used as the third layer to evaluate the quality of the change. The ten counties in the worst-hit areas of the Wenchuan earthquake were analyzed from different angles, with county region, intensity zone and ecosystem as the objects, and the following results were obtained: (1) Taking Mianzhu City as an example, from 2000 to 2010 and 2018, the conversion ratio of forest, grassland and farmland is 54.24, 59.19, 17.21, 20.06, 37.39 and 52.86%, which were distributed in the north, central and southern parts, respectively. (2) Taking the ninth intensity zone as an example, the forest landscape fragmentation increased, disturbance decreased, and species diversity increased. There is a high influence and restriction relationship between ecosystem and landscape pattern in the total landscape area change. Additionally, the relationship between them tends to develop in a benign way. As of 2018, it is in the change state of moderate imbalance-ecosystem lag. (3) Taking the county ecosystem change as an example, urban type is the best in the counties of ecosystem change, of which Shifang is the best and Pingwu is the worst. The results show that this method can effectively compare and analyze the changes in the multi-regional ecosystem pattern, which has the characteristics of universality and can also be applied to the research of ecosystem pattern change in special regions.