Abstract: Aims The symbiosis between plants and arbuscular mycorrhizal fungi (AMF) constitutes a critical nutrient transfer network in terrestrial ecosystems, playing an essential role in sustaining ecosystem functions. However, AMF community composition and its ecological mechanism underlying their functional responses to global change remains poorly understood. Methods By integrating a multi-year precipitation increase field experiment in a semi-arid grassland on the Loess Plateau with MiSeq sequencing, we measured plant biomass, root traits, and AMF community composition, and explored the effect of precipitation increase on plant resource acquisition strategies. Important findings Our results showed that precipitation increase altered plant community composition, favoring subshrubs and forbs over grasses. Compared to grass, subshrub and forb often have thicker and shorter roots, which may enhance the colonization potential of AMF. MiSeq sequencing revealed that precipitation increase significantly altered the AMF community composition, increasing the relative abundance of Gigasporaceae and Paraglomeraceae, while reducing the relative abundance of Glomeraceae. Furthermore, precipitation increase enhanced the complexity of AMF community network. In conclusion, our findings demonstrate that precipitation increase regulates plant water and nutrient acquisition pathway via altering plant functional group growth, root traits, and AMF community composition. These results indicate that precipitation increase may have profound effects on nutrient cycling in grassland ecosystems via regulating the plant and AMF interaction network.

Key words: precipitation increase, arbuscular mycorrhizal fungi, resource acquisition