Effects of experimental warming, precipitation increase and their interaction on AM fungal community in an alpine grassland of the Qinghai-Tibetan Plateau

Arbuscular mycorrhizal (AM) fungi coexist with most of terrestrial plants and participate in multiple ecosystem processes. Here we address AM fungal responses to experimental warming and a manipulation of precipitation as well as the interactions in the Qinghai-Tibetan Plateau, a hot spot region of climate change, and its associations with plant and soil characteristics. A complete randomized block experiment with warming (+2 degrees C, using open top chambers) and precipitation increase (elevated by 20%) artificially was conducted on the alpine steppe. Two years later, AM fungal community diversity and composition in the soil were analyzed with high throughput sequencing. Results showed that AM fungal community in soil was unaffected by experimental warming, precipitation increase and their interaction, including alpha-diversity and community composition and only the relative abundance of a few species changed. Most species had little connections according to the network analysis and only a few species had dense connections with others, which accorded with the characteristics of scale-free network. Besides, over 70% correlations were positive. The richness of AM fungal community was negatively correlated with sedges biomass. Besides, the relative abundance of Gigasporaceae showed a positive correlation with sedge biomass which decreased under warming treatment and soil water content, and the relative abundance of Paraglomeraceae was negatively correlated with legume biomass that increased under precipitation increase and the interaction treatment. This study demonstrated the stability of AM fungi community under short-term climate changes. Besides, correlations between AM fungal abundance at the family level and plant functional group biomass proved the connectivity of above-ground and below-ground ecosystems.