Fig. 4: Clustering distribution and structural network characteristics of China’s formulated restoration standards in different types of coastal ecosystems.

The nodes are standard documents, and the similarity value between every two standards determines the distance of the node pairs. The linkage connecting two nodes indicates that a co-citation was presented between the two standards. The size of nodes reflects the total citation number. The letters within nodes represent the hierarchy of standards: N-national, P-professional, and L-local. These restoration standards were grouped by the spectral clustering method. Documents with more than 30% similarity were clustered into a group with a common theme. The purple, green, yellow, and blue circles represent the design, implementation, monitoring, and management theme, respectively.