Response of Topsoil Fungal Community Structure to Soil Improvement Measures in Degraded Forest of Red Soil Region

Abstract

Soil fungal community structure and diversity are highly sensitive to variations in the external environment, as well as soil improvement measures. In order to clarify the effects of soil improvement measures on topsoil fertility or quality, a field experiment was conducted in eroded forest of a red soil region. Organic fertilizer, biochar, and lime+microbial fertilizer were added to the topsoil, respectively. After four years, the chemistry properties and nutrients in the topsoil were measured, and the diversity and composition of fungi were analyzed. The results showed that the additions of organic fertilizer, biochar, and lime+microbial fertilizer reduced fungal richness in topsoil, compared to that with no fertilizer addition (CK). Among them, lime+microbial fertilizer had the most negative effect on fungal richness. The three soil improvement measures also affected the diversity of topsoil fungi, but the impacts were not significant. The dominant fungal phyla in the topsoil were Ascomycota (31.29%-46.55%) and Basidiomycota (30.07%-70.71%), and the dominant fungal genera were Amphinema and Archaeorhizomyces. The effects of soil improvement measures on fungal community structure in the topsoil were different; organic fertilizer increased the relative abundance of Ascomycetes and Archaeopteroides, and biochar enhanced the relative abundance of Basidiomycetes and Archaeopteroides, whereas lime+microbial fertilizer improved the relative abundance of Basidiomycetes and Archaeopteroides. Fungal diversity and community structure in the topsoil was affected by edaphic factors, and fungal richness was regulated by pH value, whereas fungal community structure was influenced by pH, total nitrogen, and organic carbon. This study provides scientific guidance for soil improvement and ecological restoration below the canopy in eroded forests of red soil regions.