The contribution of arbuscular mycorrhizal fungi to ecosystem respiration and methane flux in an ephemeral plants-dominated desert

Arbuscular mycorrhizal fungi (AMF) can significantly influence the soil carbon cycle, however, their impacts on desert soils are still unclear. Here, a field control experiment, using in-growth mesocosms, was conducted to quantitatively assess the contribution of AMF and ephemeral plants to ecosystem respiration (R-e) and methane (CH4) flux in the Gurbantunggut Desert in China, from April to May 2017. Ephemeral plant biomass was significantly increased by AMF infection. R-e was significantly positively correlated with AMF infection rate, whereas CH4 flux was significantly negatively correlated. The contribution of AMF to R-e was up to 24%, comparable to the contribution of non-AMF microbial respiration, which accounted for up to 36%, whereas the respiration of ephemeral plants accounted for 40%. Variation in R-e was most strongly associated with soil organic carbon and soil available potassium concentrations and soil temperature. Non-AMF microorganisms accounted for most of the CH4 flux (up to 85%). In contrast, AMF only accounted for 15% of total CH4 flux. The CH4 flux was significantly influenced by soil NO3--N content, soil moisture, soil temperature and soil NH4+-N content. Overall, AMF significantly influenced R-e and CH4 flux, and also enhanced the growth of ephemeral plants, which have an important role in the carbon cycle in desert ecosystems.