In a field experiment we have examined the effect of long-term grassland management regimes (viz., intensive versits extensive) and dominant plant species (viz., Arrhenatherum elatius, Holcus lanatus and Dactylis glomerata) on soil organic carbon (SOC) build up, soil microbial communities using biomarker phospholipid fatty acids (PLFA), and the relationship between SOC and PLFAs of major groups of microorganisms (viz., bacteria, fungi, and actinomycetes). The results have revealed that changes in SOC were not significantly affected by the intensity of management or by the plant species composition or by their interaction. The amount of PLFA of each microbial group was affected weakly by management regime and plant species, but the canonical variance analysis (CVA), based on individual PLFA values, demonstrated significant (P < 0.05) effects of management regime and plant species on the composition of microbial community. Positive and significant (P < 0.01) relationships were observed between PLFA of bacteria (R-2 = 0.47), fungi (R-2 = 0.33), actinomycetes (R-2 = 0.71) and total microbial PLFA (R-2 = 0.53) and SOC content. (C) 2007 Elsevier Ltd. All rights reserved.