Responses of diversity and community composition of mixed-root-associated fungi to nitrogen and phosphorus addition: a multi-time sampling study

Many studies have examined the effects of fertilization on soil- or pure root-inhabiting fungi, but the impacts of nitrogen (N) and phosphorus (P) addition on the compositive (mixed) root-associated fungi (RAF) in forest soils remain largely unclear. In this study, we investigated how RAF communities respond to N and P inputs in a subtropical montane forest using a multiple sampling strategy. Our results showed that sampling time had a significant effect on total fungal operational taxonomic unit (OTU) richness, while the N addition had significant impacts on symbiotrophic rather than saprotrophic fungal OTU richness. RAF community composition was more strongly influenced by P- and non-P treatments regardless of sampling time, indicating that fungal communities were mainly determined by P addition. Additionally, we found that fungal diversity and community composition were influenced by season-related soil variables, which may be due to direct control of fungal activities and indirect effects on soil properties under fertilization. Together, our findings highlight the importance of considering temporal variation in RAF responses to fertilization for a more comprehensive understanding of fungal community dynamics.