High AMF diversity benefits ecosystem multifunctionality
Our results confirmed that high AMF diversity enhanced ecosystem
multifunctionality, aligning with our expectations. Previous studies
have already demonstrated the benefits of AMF diversity on ecosystem
primary net productivity (Wagg et al., 2011) and nutrient reserve (Köhl
and van der Heijden, 2016). In our study, the increase of ecosystem
multifunctionality through high AMF diversity was primarily mediated by
improved plant growth, particularly in net photosynthetic rates and
aboveground biomass (Figure 3). Contrary to our expectations, high AMF
diversity had no significant effect on most soil functions, compared to
low AMF diversity (Figure 4, Table 1). This may stem from our use of
sterilized soil, which was only inoculated with AMF without introducing
other fungi or bacteria.
Increasing evidence suggests that the nutrient cycling functions of AMF
are not performed in isolation but require collaboration with other soil
microorganisms (Zhang et al., 2022; Sun et al., 2023; Wang et al.,
2024). For instance, previous results have linked soil functions, such
as organic nitrogen availability (Rozmoš et al., 2022) and soil
N2O emissions (Li et al., 2023b) to the hyphosphere core
microbiome. In our experiment, the absence of soil microbial communities
likely prevented AMF from recruiting distinct microbes into their
hyphosphere, thereby diminishing the contribution of AMF diversity to
soil functions. A global meta-analysis of field experiments highlighted
a positive correlation between ecosystem multifunctionality and AMF
richness (Ma et al., 2021). However, this correlation may not be
directly due to the AMF alone but rather influenced by the hyphosphere
microbiomes.
Thus, we speculate that the high plant productivity in high plant
diversity communities may not be solely due to plant diversity itself. A
study by Wilsey et al. (2023) found that biodiversity in native
plant-dominated communities was significantly positively correlated with
net primary productivity. However, this positive correlation is
eliminated in communities dominated by exotic species, which may be due
to the presence of more pathogenic microorganisms in exotic
plant-dominated communities. This highlights the importance of multiple
trophic levels BEF study. Previous results have shown that multi-trophic
diversity can better explain and predict ecosystem multifunctionality
than single-trophic level diversity (Soliveres et al., 2016; Li et al.,
2024). Li et al. (2024) found that different trophic groups exhibit
varying correlations with ecosystem functions. For example, in
grasslands, AMF diversity showed a significant correlation with
provisioning multifunctionality (including plant productivity and
community stability), rather than with multifunctionality (Li et al.,
2024), which is consistent with our findings.