Inland Wetland Harbors Richer Arbuscular Mycorrhizal Fungal Communities than Mangrove Forests: Insights from an 18S Meta-analysis Study

Wetland ecosystems play important ecological functions but remain the least studied habitats for arbuscular mycorrhizal fungi (AMF) compared to terrestrial ecosystems. Prior studies were often conducted in a small spatial area and focused only on a single wetland type, limiting our understanding of wetland communities in large-scale wetlands. To address this gap, we conducted a meta-analysis of 380 wetland samples from the wetland habitat, targeting the 18S rDNA region, focusing on high-throughput sequencing (HTS) data. In this study, we deliver large-scale dataset syntheses of AMF across multiple wetland types using a standardized pipeline. We categorized wetlands into inland wetlands (freshwater wetland and rice farm) and coastal wetlands (mangrove forest and salt marsh). This meta-analysis study revealed clear differences in AMF richness between inland and coastal wetlands. AMF richness was significantly higher in inland wetlands (freshwater and rice ecosystems) than in coastal wetlands (mangrove and salt marsh), with mangroves showing the lowest richness among all habitats. Habitat explained broader variation, whereas sample type showed a smaller but more consistent effect. Moreover, soil pH showed a positive correlation (R = 0.18, p = 0.00043), while mean annual precipitation (MAP) (R= –0.42, p <2.2 × 10−16) and mean annual temperature (MAT) (R = -0.35, p = 1.1 × 10−12) were negatively correlated with richness. Beta diversity analysis indicated that species turnover was more dominant than nestedness across different wetland types. Overall, AMF communities in wetlands are associated with soil pH and climate (MAP), with differences mainly driven by species turnover. The insight from this study reveals that mangrove wetlands are hosts to unique AMF diversity pools, despite low local richness. Moreover, this this study provides insights into mechanisms that may contribute to ecosystem resilience.