Enzymic involvement in the biogeochemical responses of a Welsh peatland to a rainfall enhancement manipulation

Abstract

 Microbial enzyme activities were followed during a field-based experimental simulation of the effects of higher rainfall in a Welsh peatland. The treatment did not significantly affect the activities of the carbon cycling enzymes, β-glucosidase, esterase or xylosidase. In contrast, the activity of the enzyme sulphatase decreased by 44% (P<0.001) in response to the wetter conditions. The manipulation suggests that should climate change cause conditions to become wetter in peatlands, then (with the exception of sulphatase) current levels of wetness may be sufficient to limit decomposition processes, and thus any further increase in wetness is unlikely to induce a further decrease in decomposition rates. Correlations were found between the esterase activity and both nitrous oxide flux (r=–0.44, P<0.05), and methane release (r=0.53, P<0.01). Likewise, there was a correlation between xylosidase activity and both carbon dioxide emission (r=0.52, P<0.01) and aluminium concentration (r=0.58, P<0.01). All of the enzymes correlated positively with dissolved organic carbon (range r=0.53, P<0.01 sulphatase to r=0.61, P<0.001 glucosidase). Together, the correlations lend support to recent hypotheses suggesting that enzymes exert an influence over wetland biogeochemical properties.