Evaluating landscape ecological sensitivity of an estuarine island based on landscape pattern across temporal and spatial scales

Evaluating landscape ecological sensitivity in estuarine areas is important for providing reference for landscape optimization and ecological conservation, however, the comprehensive characteristics of the landscape ecological sensitivity, including the changes under various disturbances, the spatiotemporal heterogeneities, and the multiple scale effects, have received insufficient attention. A model to evaluate estuarine landscape ecological sensitivity was established based on landscape pattern across temporal and spatial scales. Two new indices, namely, landscape ecological condition index (LECI) and landscape ecological sensitivity index (LESI), were proposed using remote sensing and geographic information system methods. Chongming Island, a typical and important estuarine area in China, was selected as the study area to demonstrate the model. Evaluation factors were integrated following the landscape pattern; different years and periods in the last 30 years were used to reflect the temporal scales; and spatial scales of 100 m, 200 m, 400 m, and 800 m, which refer to the evaluation unit size, were adopted to validate the spatial scale effect and seek the optimal scale to apply the model. Results indicated that the LECI initially slightly decreased and then increased from 1988 to 2017, and the LESI continuously increased along the periods. The two indices exhibited distinct spatiotemporal heterogeneities, which were driven by different development goals and strategies of the island in different periods. Along the scales from 100m to 800 m, the LECI and LESI in the entire study area gradually decreased; they tended to be homogenizing, and the details were lost in the spatial distributions. The 200m scale balanced all the demands of accuracy, spatial heterogeneity, and appropriate data volume, and was the optimal spatial scale to apply the model. The application of the model in Chongming Island verified its effectiveness to represent the comprehensive characteristics of the estuarine landscape ecological sensitivity, and the model can be widely used in different estuarine areas because of its high applicability.