UPGMA clustering of soil DGGE fingerprints using the pearson moment-based similarity coefficient. Similarity percentages between Acinetobacter microbial populations using the PCR–DGGE specific system are indicated above. F.M. and F.H. correspond to microcosms F70_MN and F70_HNa while T1, T3, T4, T5, T6, T9 indicate the corresponding sampling time. Samples analysed in duplicate are indicated with the same name.