Spatial grain size effects of landscape metrics in different gradients of coastal areas

As an essential object of regional development and utilization, the coastal area was affected by the increasing human activities, resulting in a profound impact on the coastal landscape. However, how landscape metrics respond to increasing spatial grain size in coastal areas remains unclear. Therefore, four gradients are divided according to the distance from the coastline, and 16 landscape metrics are introduced in this study. The spatial grain size effects of multiple landscape metrics in different gradients of coastal areas were analyzed using the methods of change trend analysis, variation coefficient, and Fragstats model. It was revealed that apart from the diversity metrics, the responses of the density metrics, area and edge metrics, shape metrics, and distribution metrics to increasing grain size were highlighted in coastal areas. There were significant differences in spatial grain size effects of landscape metrics in different gradients of coastal areas. The sensitivity of most landscape metrics to increasing grain size in gradient I the (region near the coastline) was evidently higher than that of other gradients (regions far away from the coastline). Furthermore, the composition, proportion, and distribution of landscapes in different gradients of coastal areas under the influence of human activities are crucial factors influencing the grain size effects of landscape metrics.