Seagrass restoration at the right time in the right site with right methods can generate persistent carbon benefits in China

Zostera japonica beds have declined substantially along the coast of China, highlighting the need for targeted and effective restoration planning. This study develops a restoration roadmap that supports China’s carbon neutrality goals by addressing three key questions: where restoration should occur, when it should be implemented, and which methods should be used. Field surveys, satellite remote sensing, genetic data, and species distribution modelling were integrated to identify restoration opportunities under current and future climate conditions. The results indicate that northern China, particularly the Bohai Sea region, contains the largest extent of suitable and persistent habitat, whereas several southern populations have experienced substantial bed degradation. A rule-based restoration decision framework combined seagrass bed decline and genetic diversity to recommend region-specific restoration strategies across the species range. The phased framework prioritizes areas suitable under current and 2050s conditions, particularly those projected to remain suitable by the 2100s, while treating areas becoming suitable mainly by the 2100s as long-term adaptive reserves. By the 2100s, approximately 103,371 ha of potential suitable habitat is projected, corresponding to an estimated potential carbon stock of 10.86 Tg C. These findings provide a spatially explicit framework for improving Z. japonica restoration planning and evaluating its potential long-term carbon benefits in China.