Potential enzyme activities of polyphenol oxidase (A) expressed as mg g−1 3 h−1 and peroxidase (B) expressed as mg g−1 h−1 for tested subtropical wetland soils (i.e., YT, XZ, and XX) sampled on 16 December 2010 under experimental warming. Error bars are +1 standard deviation. Asterisks represent significant Student's t test differences between warmed and control samples (*, P < 0.05; **, P < 0.01).