The ecosystem of tropical coral islands is relatively isolated, characterized by harsh environmental conditions. It is frequently subjected to climatic stressors such as high temperatures, intense solar radiation, high salinity, and seasonal drought. Moreover, island ecosystems host relatively few species, exhibit simple ecosystem structures, possess weak self-regulating capacity, and are inherently unstable. As a result, artificial vegetation often struggles to persist over the long term and is susceptible to degradation, posing significant challenges to vegetation restoration and the enhancement of ecological functions. Thus, ensuring the stability and health of such ecosystems, and facilitating the establishment of self-sustaining plant communities, have become crucial scientific and technological issue that urgently needs to be addressed in advancing marine ecological civilization and maintaining ecological safety on islands.

Using long-term vegetation monitoring plots established on tropical coral islands in China, South China Botanical Garden, Chinese Academy of Sciences, selected five typical types of artificial vegetation: grassland, windbreak and sand fixation forest, shelterbelt, public green space, and roadside trees. Using native vegetation as an ecological reference, high-throughput sequencing, phospholipid fatty acid (PLFA) profiling, and co-occurrence network were employed to systematically track dynamic changes in soil microbial communities and soil properties during the early stages of vegetation restoration (0‒2 years).

The study revealed that although artificial vegetation significantly improved the soil properties and nutrient availability, key indicators—including soil fertility, microbial biomass, enzyme activity, and biodiversity—remained substantially inferior to those of native vegetation within the first two years of restoration. Marked differences in restoration efficiency were observed among vegetation types: grassland and roadside trees, which received intensive management such as irrigation and fertilization, recovered significantly faster than windbreak and sand fixation forest and shelterbelt.

A key breakthrough of this study is the first demonstration of a “division of labo” among soil microbes during ecological restoration on tropical coral islands. In the initial phase, soil fungi act as “pioneers”: leveraging their tolerance to drought and salinity, they efficiently break down recalcitrant organic matter, facilitate plant colonization, and play a central role in stabilizing microbial network structure. As restoration progresses, bacterial biomass gradually increases and serves as “module hubs” within the co-occurrence network. By driving the cycling of carbon, nitrogen, and phosphorus, bacteria become the “main force” in maintaining long-term ecosystem functioning and stability. Additionally, the study found that soil microbial activity in both artificial vegetation and native forests on tropical coral islands is co-limited by carbon and phosphorus, indicating that nutrient scarcity is a critical bottleneck constraining microbial activity and restoration efficiency.

Based on these findings, tailored optimization strategies were proposed: during initial vegetation establishment, inoculating salt-tolerant fungal agents can accelerate the conversion of recalcitrant carbon, supply nutrients for plant growth, and save critical restoration time. In later stages, easily decomposable carbon sources can be supplemented in small, frequent doses to promote the development of bacterial functional communities. Given the high calcium and low phosphorus content typical of tropical coral island soils, the coordinated application of low-dose phosphate fertilizer is recommended to precisely alleviate carbon‒phosphorus co-limitation and enhance restoration efficiency. Longer-term monitoring was also suggested to be implemented to evaluate the sustainability of different restoration models, further refine ecological restoration techniques for tropical coral islands, and provide a scientific basis for ensuring island ecological security and restoring fragile ecosystems worldwide.
DOI: 10.1007/s42832-025-0370-7