Soil microbial community structure and diversity in a turfgrass chronosequence: Land-use change versus turfgrass management

Abstract

A diverse soil microbial community is an important measure of sustainable land use. Turfgrasses are usually managed as a monostand, which may result in reduced soil microbial diversity. However, there is little information on the structure and diversity of soil microorganisms in managed turfgrass systems. We examined the soil microbial community in a turfgrass chronosequence (i.e., 1, 6, 23 and 95 years), established from native pines, to address (1) the degree to which microbial diversity is achieved and maintained in turfgrass soils and (2) the relative importance of turfgrass management versus land-use change (i.e., native pines to turfgrass) in structuring the soil microbial community. Soil microbial communities were fingerprinted using phospholipid fatty acid (PLFA) composition, and also by the pattern of sole C source utilization (i.e., community-level physiological profiles, CLPP). The relative diversities of soil microbial communities as a function of land use and turfgrass ages were compared using the Shannon index. Multivariate analysis was used to detail variations in soil microbial communities. Despite the differences in land use and turfgrass age, microbial biodiversity was generally similar for the various soils, with the exception that diversity was lower in soils taken from 5 to 15 cm depth of the two youngest turfgrass systems. This reduction was correlated with low soil C, and suggests that soil organic matter (OM) is a primary determinant of microbial community diversity. Both CLPP- and PLFA-based principal component analyses (PCA) revealed distinct groupings of soil microbial communities based on land use but not on turfgrass age. There was a preferential use of phenolic compounds and carboxylic acids by the microbial community in native pine soils, whereas carbohydrates were the preferred C source for microbial communities in turfgrass soils. This difference in catabolic function was mirrored by a compositional change of phospholipid fatty acids. Cluster analysis of community structure indicated that microbial communities in older turfgrass systems (23 and 95 years old) diverged from younger systems (1 and 6 years old), implying some effect of management on composition and structure of the soil microbial community. Our study concludes that a diverse soil microbial community was achieved and maintained in turfgrass systems, and that shifts in soil microbial community structure were attributed primarily to the change of land use rather than the length of turfgrass management.