Microbial community responses to tallgrass prairie restoration

Until recently, little was known about the below-ground microbial communities associated with tallgrass prairies, or the responses of those communities to disturbance or ecosystem restoration. In this study a series of tallgrass prairie restorations in Illinois were compared with nearby native prairie remnants or agricultural sites in terms of soil quality indicators and microbial community characteristics. Preliminary work showed that the upper 1 - 5 cm of soil consistently had higher microbial biomass and soil organic matter than deeper soil layers, as well as faster responses to restoration, and the rest of the study focused on this upper soil layer.  Soil organic matter, water holding capacity, organic C, N, and S, C:N, and C_mic:C_tot correlated with restoration age (ranging from 7 to 24 years), while bulk density and nitrate decreased with age. Total microbial biomass (as total phospholipid fatty acids) also increased with restoration age, as did the proportion of PLFA attributed to bacteria.  Poly-beta-hydroxybutyrate (PHB, an indicator of unbalanced bacterial growth), as well as other stress indicators (ratios of iso:anteiso PLFAs and normal saturated:monounsaturated PLFAs) also significantly decreased with restoration age. PLFA profiles of the restoration soils were distinctly different from both native remnant soil and agricultural soil, and a relatively small subset of PLFAs could be used to discriminate between the sites. RDA analysis showed that the measured environmental variables could explain 80% of the PLFA variability. Based on these results, it appears that prairie restoration and maintenance increase both surface soil quality and the health of the soil microbial community, with implications for long-term carbon sequestration.