Contrasting community responses of root and soil dwelling fungi to extreme drought in a temperate grassland

Fungal communities inhabiting plant roots and the soil diverge because they are shaped by differences in abiotic environment and plant filtering. Therefore, these two communities will also likely respond differently to climate change. However, such responses are poorly understood, especially for climate extremes with increasing frequency and intensity. Based on a long-term field experiment that simulated two types of extreme drought (chronic/intense) of once-in-20-year occurrence in the temperate grassland, we studied the response of soil and root fungal communities to extreme drought in association with plant communities. The species richness, community composition, and network stability of the root fungi were sensitive to extreme drought and showed legacy effects during recovery; notably, these responses were independent of extreme drought types. The sensitivity of the root community was mainly driven by rare symbiotic and saprotrophic fungal species, with abundant species remaining stable. In contrast, except for species relative abundances, soil fungal communities were resistant to drought. Structural equation modelling revealed that plant communities mediate drought effects on root fungal communities but not soil communities. Our findings highlight the climate sensitivity of root fungal communities and their response asymmetry to soil communities, with potentially profound consequences for ecosystem stability and functionality.