Species-specific effects of plants colonising cutover peatlands on patterns of carbon source utilisation by soil microorganisms

Root exudates and litter are the main sources of inputs of labile carbon into the microbial pool in successional ecosystems. Here we studied whether typical pioneer species (Eriophorum vaginatum, Eriophorum angustifolium and Calluna vulgaris) alter the functional response of the microbial community of a previously cutover peatland. Peat was sampled at three depths (0–5, 20–25 and 40–45cm) from beneath these species and from bare soil areas. MicroResp analysis using ecologically relevant, radiolabelled, carbon sources showed significant separation in community level physiological profiles (CLPP) of soil microorganisms according to peat depth. This effect was also reflected in microbial biomass carbon, which also decreased with increasing depth. Furthermore, distinct differences in CLPP were observed between the three plant species and the bare soil in the absence of an effect on microbial biomass carbon or total soil carbon. The plant species effects were driven by differential utilisation of xylose, glutamic acid, lysine and phenylethylamine. The data suggest that ‘new’ carbon inputs from plants colonising abandoned cutover peatland may support communities of microorganisms that have functionally distinct roles in carbon turnover.