Abstract
Global nitrogen eutrophication, which is disrupting the intimate plant–arbuscular mycorrhizal fungi (AMF) symbiosis, can alter the diversity and physiological functions of soil AMF greatly. However, shifts of beta diversity and the intrinsic patterns of AMF community dissimilarities in response to nitrogen addition remain unclear. Based on a 7-year nitrogen addition experiment in a Qinghai–Tibet Plateau alpine meadow, we detected the changes in soil AMF alpha diversity (richness and genus abundance) and the community composition beta diversity by partitioning the two components of Simpson and nestedness dissimilarities along (turnover) and within (variation) nitrogen addition treatments, and fitted with environmental factor dissimilarities. We found that nitrogen addition decreased AMF richness by decreasing the most dominant AMF genus of Glomus but increasing the abundance of the rare genera. The turnover of the AMF community overall beta diversity along the nitrogen addition gradients was induced by the increased nestedness dissimilarity, while the variation within treatments was explained by both increased Simpson and nestedness dissimilarities, which was significantly correlated with soil pH. Our study found both Simpson and nestedness dissimilarities worked on the AMF community dissimilarity after nitrogen addition and the significant variation within the same treatment, which would be important in the future for predicting global AMF or microbial diversity changes in response to nitrogen eutrophication.
Highlights
Arbuscular mycorrhizal fungi, which belong to the phylum Glomeromycota, are widely distributed in soil and plant roots (Smith and Read, 2008; Davison et al, 2015)
The turnover of the AMF community β-bray (ER 3.54 × 1035; deviance explained (De) 45.15) and the β-sor (ER 6.95 × 109; De 15.77) dissimilarities both significantly increased with nitrogen addition, FIGURE 4 | Principal coordinate analysis (PCoA) by PERMANOVA showing the association of soil AMF community dissimilarities along and within nitrogen addition treatments
We found that AMF richness decreased and the relative abundance of different AMF genera was altered differently after nitrogen addition
Summary
Arbuscular mycorrhizal fungi, which belong to the phylum Glomeromycota, are widely distributed in soil and plant roots (Smith and Read, 2008; Davison et al, 2015). Nitrogen Addition and AMF dependence of plants (Treseder, 2004; Liu et al, 2012), which could result in a decrease in AMF alpha diversity in soil. A meta-analysis showed a negative but nonsignificant relationship between the AMF richness and nitrogen addition (Han et al, 2020), which may be due to variation among different ecosystems, treatment forms, rates, soil properties (EgertonWarburton et al, 2007; Camenzind et al, 2014; Zheng et al, 2014), and/or the abundance shift of specific AMF taxons with specific functions. Identifying the changes in alpha diversity and taxon abundance of AMF species in soil under long-term nitrogen addition is meaningful but not useful for discovering the functional properties and their role in the ecosystem process
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