Temporal dynamics of microbial communities on decomposing leaf litter of 10 plant species in relation to decomposition rate

Few empirical studies have examined how microbial communities on decomposing litters change in relation to litter chemistry or how microbial community composition is related to the rate of decomposition. We examined the relationships among microbial community composition, litter chemistry, and decomposition rates in a common garden experiment of the decomposition of leaf litters of 10 plant species. Microbial community composition, as measured by phospholipid fatty acids (PLFA), and 7 litter chemistry variables (%N, C:N, four carbon fractions, and lignin:N) were examined at 1, 2, and 8 months into decomposition. Both microbial and litter chemistry variables were reduced to a single axis each through nonmetric multidimensional scaling (NMS) to examine the relationship between microbes, litter chemistry, and decomposition rates. Although microbial communities were separated according initial litter chemistry and lability, individual measures of litter chemistry had limited ability to predict microbial community composition during decomposition. Decomposition rate constants were explained by litter chemistry of initial, 1-, 2- and, 8-month old litters (60–72% of the variance), and by microbial community composition at the 8-month collection date (67%). The results suggest that initial litter chemistry determines the rate of decomposition and microbial community composition early in decomposition while the composition of the microbial community plays a more important role in determining decomposition rate later in decomposition.