Table 4 Using specific PLFAs as biomarkers (see Section 2), we can quantify the relative abundances of specific microbial groups within the soil profiles (Table 4). In both profiles, Fig. 3. Principal component analysis (PCA) of PLFA signatures (mol percentages) from soil samples collected at different depths within the two profiles. The same symbols are used for the different depth increments in the valley and terrace profiles. The valley profile samples are represented by the filled symbols. PC1 explains 42% of the variance in the PLFA data, PC2 explains 12%, the individual scores are unit less. Error bars indicate + 1 SE (N = 3).