AMF diversity provides stable benefits for plant growth
Although the positive effects of high AMF diversity on multifunctionality are no longer significant under multiple GCFs, its contribution to plant aboveground biomass has become more pronounced. Several studies suggest that the benefits of AMF diversity become more pronounced when host plants are subjected to multiple stressors (Crossay et al., 2019; Gosling et al., 2016; Tang et al., 2023). This aligns with our findings regarding aboveground biomass, where under single GCF conditions, plants in the high AMF diversity treatment exhibited 8.36% greater aboveground biomass than those in the low diversity treatment. Remarkably, this difference increased to 31.60% under multiple GCFs condition (Figure 3b). The differential performance may be related to the selection preferences of host plants in varying environmental contexts. AMF selection is influenced by both the environment and the host plant itself. Under single GCF conditions, plants tend to favor specific AMF taxa that are better equipped to mitigate environmental stress and enhance carbon resources acquisition (Tang et al., 2023; Vályi et al., 2016). Although multiple GCFs intensified competition among AMF, they also strengthened the host plants’ selection for AMF species, allowing high AMF diversity still exert a positive effect on plant performance under multiple GCFs.
High AMF diversity consistently enhanced plant net photosynthetic rate and aboveground biomass under all GCF scenarios, exceeding both the average effect of individual AMF inoculations and, in most cases, the effect of the single most effective AMF (Figure 3). This illustrates the complementarity among AMF species when inoculated as a mixture. These findings contrast with previous meta-analysis indicating that multi-species AMF inoculation does not significantly enhance plant performance compared to single-species inoculation under single GCF (Tang et al., 2023). However, it has been shown that multi-family AMF assemblages can boost plant performance indicating that it is not the number of AMF species that enhances plant performance, but rather the phylogenetic diversity within the AMF community (Gosling et al., 2016; Tang et al., 2023). Thus, the functional complementarity among different AMF families could become increasingly crucial when multiple GCFs occur simultaneously (Gosling et al., 2016; Horsch et al., 2023; Tang et al., 2023).