Conversion of grassland to abandoned land and afforested land alters soil bacterial and fungal communities on the Loess Plateau

Abstract

On China's Loess Plateau (CLP), shifts in land use are particularly influential in altering soil microbial communities. While one might expect shifts between grassland, forest and arable land to affect soil microbial communities, the specific ensuing responses of bacterial and fungal diversity and composition on the CLP are poorly understood. Soil microbial diversity and composition among the CLP's native grasslands, afforested lands, and ‘abandoned’ arable lands (fallow roughly 10 years in 2020) were determined using high-throughput sequencing of 16S rRNA and ITS genes. A comparison of land use types showed the abandonment of arable land and grassland afforestation to have had a negligible impact on soil bacterial α-diversity but to result in significantly lower soil fungal diversity. Grassland afforestation also increased fungal richness. Both bacterial and fungal β-diversity differed significantly among the land uses. Conversion of grassland to abandoned land significantly altered the relative phylum-level abundance of bacteria (except that of the Acidobacteria), but not that of fungal phyla. Grassland afforestation only influenced the abundance of bacteria and fungi of lower relative abundance (<10 % except Proteobacteria). The quantity of above- and below-ground biomass and soil properties explained most of the variation in soil microbial communities. Having important ecological implications, these findings can inform land management decisions in the study area and similar ecologically-fragile regions.