The soil microbial community of turf: linear and nonlinear changes of taxa and N-cycle gene abundances over a century long turf development

Abstract

Turf, consisting of closely-spaced grasses and the subtending soil, is a unique ecosystem subject to intense management. Yet, soil organic matter accumulates quickly and reaches equilibrium after 20 to 50 years. Resource availability is an important driver of species richness and theoretically their relationship is expected to be unimodal. In this work, we examined the effects of turf development (i.e. 1, 15, 20, and 109 year-old chronosequence) on microbial taxon richness, community composition, and abundances of genes putatively involved in N cycling through 16S rRNA gene and ITS region amplicon sequencing. Microbial alpha-diversity remained relatively stable although soil organic C and N increased up to 3 folds over a century long turf development. However, both bacterial and fungal community compositions changed substantially from those in the previous land use, pine stands and along turf development. Youngest turf was closer to the oldest turf than to middle-aged ones, specifically for bacterial community. Microbial changes to resource availability were also taxonomically specific. The relative abundance of Proteobacteria was independent of resource availability; Nitrospirae increased monotonically, and Bacteroidetes, Actinobacteria, and Glomeromycota varied curvilinearly. However, abundances of most taxa from the phylum to OTU level and N-cycle genes varied nonlinearly with turf development.

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