Warming exerts a stronger effect than nitrogen addition on the soil arbuscular mycorrhizal fungal community in a young subtropical Cunninghamia lanceolata plantation

Warming and nitrogen (N) deposition are two important aspects of environmental change influencing plants, microbes, and soil processes. Despite the crucial role of arbuscular mycorrhizal (AM) fungi in terrestrial ecosystems, how warming and N addition interactively affect the AM fungal community remains poorly understood. We conducted a 3-year field experiment to examine the effects of soil warming (+5 ℃) and N (40, 80 kg N ha⁻¹ y⁻¹, as LN and HN, respectively) addition on the soil AM fungal community composition in a 4-year-old Cunninghamia lanceolata plantation. The results indicated that warming, regardless of N addition, significantly decreased AM fungal diversity and altered AM fungal community composition, while N addition alone had only minor effects. More importantly, the changes of soil AM fungal diversity and community composition were greater in the warming plus N addition treatments than in the warming-only treatment, indicating that N addition intensified the effects of warming on the soil AM fungal community. Warming altered the soil AM fungal community composition, with decreases in the abundance of Glomeraceae and increases in the abundances of Ambisporaceae, Acaulosporaceae, Paraglomeraceae and Gigasporaceae. Furthermore, warming and N addition significantly increased root mycorrhizal colonization, with the greatest increase under the warming plus HN treatment. Altogether, our results suggest that warming predominantly altered the soil AM fungal community composition and strengthened the interaction between plants and AM fungi in this subtropical forest, while N addition could intensify the effects of warming on the plant-AM fungi system.