Saltmarsh represents a classic model of primary succession, yet the processes underlying its initiation and development, especially in response to human influences, remain poorly understood. We conducted annual vegetation surveys on a newly formed saltmarsh in the South China Sea and compared plant communities across tropical coral salt marshes exposed to varying levels of human influence. We also investigated the environmental factors and human activities shaping community compositions. Pioneer grass species rapidly colonized the site within one year following land reclamation, with a grass-to-shrub transition concurrently with dike construction, indicating a clear trajectory of species establishment and development. Land reclamation and biological invasion facilitated the early establishment of pioneer grasses, initiating primary saltmarsh succession. The accelerated transition to shrub-dominated communities was likely driven by dike construction and the introduction of stress-tolerant shrub species.

Practical implication: Our results highlight the pivotal role of human activities in both initiating and accelerating primary saltmarsh succession. These insights are critical for informing effective restoration and land management strategies in tropical coral saltmarsh ecosystems.

We conducted annual vegetation surveys on a newly formed saltmarsh in the South China Sea and compared plant communities across tropical coral saltmarshes exposed to varying levels of human influence. We classified disturbance levels as high-disturbance (i.e., Yongshu Island), intermediate-disturbance (i.e., Chenhang Island and Guangjin Island), and low-disturbance (i.e., Dong Island).