Trait‐based assembly of arbuscular mycorrhizal fungal communities determines soil carbon formation and retention

Abstract

Fungi are crucial for soil organic carbon (SOC) formation, especially for the more persistent mineral-associated organic C (MAOC) pool. Yet, evidence for this often overlooks arbuscular mycorrhizal fungi (AMF) communities and how their composition and traits impact SOC accumulation.We grew sudangrass with AMF communities representing different traits conserved at the family level: competitors, from the Gigasporaceae family; ruderals, from the Glomeraceae family; or both families combined. We labeled sudangrass with 13 C-CO 2 to assess AMF contributions to SOC, impacts on SOC priming, and fungal biomass persistence in MAOC.Single-family AMF communities decreased total SOC by 13.8%, likely due to fungal priming. Despite net SOC losses, all AMF communities contributed fungal C to soil but only the Glomeraceae community initially contributed to MAOC. After a month of decomposition, both the Glomeraceae and mixed-family communities contributed to MAOC formation. Plant phosphorus uptake, but not hyphal chemistry, was positively related to AMF soil C and MAOC accumulation.Arbuscular mycorrhizal fungi contribution to MAOC is dependent on the specific traits of the AMF community and related to phosphorus uptake. These findings provide insight into how variations in AMF community composition and traits, and thus processes like environmental filtering of AMF, may impact SOC accumulation.

Distinct, direct and climate‐mediated environmental controls on global particulate and mineral‐associated organic carbon storage

“…Several recent studies demonstrate that additional soil physicochemical properties not included in this study, especially exchangeable Ca and Fe‐ and Al‐hydroxides, are better predictors of MAOC storage than % sand alone (King et al., 2023; Kirsten et al., 2021; Rowley et al., 2021). Microbial traits including mycorrhizal type (Craig et al., 2018; Horsch et al., 2023; Keller et al., 2021) and transformation efficiency may be additional modulators of both SOC fraction storage and f MAOC , though the majority of studies on microbial transformations have focused primarily on their effects on microbial‐derived MAOC (e.g., Craig et al., 2022; Ernakovich et al., 2021; Kallenbach et al., 2016; Liang et al., 2019). While satellite‐based NPP data is often used as a proxy for C inputs to the soil (e.g., Chen et al., 2021; Eclesia et al., 2016; He et al., 2023), it may not be as applicable to agricultural systems, where depending on management strategy, plant residues are often removed from the soil.…”

Bridging 20 Years of Soil Organic Matter Frameworks: Empirical Support, Model Representation, and Next Steps

“…There has been limited testing of the importance of hyphal density as of yet, but current evidence suggests hyphal density may be particularly important for stable SOM formation in AM and N-rich systems but may reduce MAOM formation in ECM systems (Hicks Pries et al, 2023;Horsch et al, 2023;Zhu, Zhang, et al, 2022). Whalen et al (2024) comprehensively tested whether a suite of soil fungal traits are linked to SOM formation potential and found that the formation of stable, chemically diverse SOM fractions was promoted by "multifunctional" species with intermediate investment across a group of traits (i.e., CUE, growth rate, turnover rate, and biomass protein and phenol contents), emphasizing the importance of trait synergies.…”

Strain-specific evolution and host-specific regulation of transposable elements in the model plant symbiontRhizophagus irregularis

“…This relationship may have been established since plants first conquered the land 2 , and there is evidence showing that AMF improve plant growth and ecosystem productivity 3 . More recently, it was also reported that these symbionts can retain atmospheric carbon, indicating these play a significant role in the global climate balance 4,5 . Nonetheless, despite their relevance for plant fitness and long-term evolution, AMF show low morphological variability with no apparent plant specificity 6 .…”