Available nutrients affect fungal compositions and functions under land use conversions in alkaline grassland in northeastern China

Abstract

Abstract Purpose: Little is known about the link between the fungal community and soil nutrient availability when land use is converted from abandoned farmland to grassland in the alkaline grasslands of northeastern China. Methods: Therefore, in this study, the diversity, composition, and function of fungi, as well as basic soil properties and inorganic phosphorus fractions, were investigated under land-use conversion from maize cropland to alfalfa (AG), Lyemus chinensis (LG), and restored grasslands (RG). Results: The results showed that the relationships between Olsen-P and the Pi fractions of Ca8-P, Fe-P, Ca2-P, and Ca10-P were close. Significantly elevated available phosphorus (Olsen-P) and available nitrogen (AN) values were found in the 0-10 cm and 10-20 cm soil layers, respectively, in the AG treatment, relative to LG and RG treatments (P < 0.05). The O-P content at 0-10 cm and Al-P content at 10-20 cm in the RG treatment were the highest. The RG treatment increased the Shannon index of fungi and the abundances of Mortierellomycota, Glomeromycota, and Mortierella, while decreasing the abundance of Cladosporium. The RG treatment greatly reduced plant pathogens and enhanced mycorrhizal and ectomycorrhizal growth. Olsen-P and AN were both positively correlated with plant pathogen abundance (P < 0.01). Mycorrhizal fungi had negative effects on Ca8-P, Fe-P, Olsen-P, and AN (P < 0.01). Conclusion: Land-use conversion from maize cropland to restored grassland could reduce the abundance of some plant pathogens and enhance useful fungi by decreasing the availability of P and N.