Arbuscular mycorrhizal fungi regulation of soil carbon fractions in coal mining restoration: Dominance of glomalin-related soil proteins revealed by stable carbon isotopes (δ13C)

Abstract

Arbuscular mycorrhizal fungi (AMF) play a pivotal role in soil carbon cycling by orchestrating the recruitment of microbial communities and establishing hyphal networks. Understanding whether these attributes of AMF are instrumental in restoring soil carbon pools in areas disrupted by coal mining is crucial for forecasting soil organic carbon (SOC) dynamics in post-disturbance restoration sites. This study conducted a year-long, in-situ leaf decomposition experiment (comprising three shrubs: Amorpha fruticose, Caragana, and Sea buckthorn; two treatments: inoculated with AMF and without AMF inoculation) at the mycorrhizal restoration demonstration base in Inner Mongolia's mining area. Utilizing stable isotope technology, we investigated the mycorrhizal regulatory effects on aggregate carbon dynamics during the leaf decomposition process. Our findings showed that the presence of AMF hyphae accelerated carbon transformation within aggregates, resulting in augmented content of mineral-bound carbon (+6.1 %) and δ¹³C abundance (7.1 %) within microaggregates in sea buckthorn plots. Analysis employing random forest and partial least squares regression models corroborated that the regulation of mycorrhizal dynamics on aggregate carbon composition after fresh leaf input was indirectly influenced by GRSP rather than directly by AMF hyphae. In summary, our findings elucidate the evolving patterns of aggregate carbon dynamics following AMF inoculation in coal mining reclamation sites under field conditions. This underscored the efficacy of planting sea buckthorn and inoculating AMF during the vegetation restoration process of open-pit mine reclamation land in Inner Mongolia.