Greenhouse gas emissions from peatlands under manipulated warming, nitrogen addition, and vegetation composition change: a review and data synthesis

Abstract

Peatlands play an essential role in carbon cycling and global warming. However, the feedback of peatlands to global changes is still unclear. Here, we conducted a data synthesis of 236 observations from 52 field experiments to evaluate the effect of three important global changes (warming, nitrogen addition, and vegetation composition change) on three major greenhouse gas (GHG) fluxes: CO2, CH4, and N2O. The results showed that (i) GHG responses to warming varied among warming methods, between air temperature increase rates, and between warming durations; (ii) GHG responses to N addition varied between peatland types, between N forms, between N concentrations, and between experimental durations; (iii) the response rates of GHGs were associated with local environmental parameters (mean annual precipitation, MAP; and water table level, WTL); (iv) the global warming potential (GWP) considerably increased under these global changes, which indicates that cooling function of peatlands will be weakened. Overall, given these global changes occur simultaneously, the interaction of them on GHG fluxes should not be ignored. Our results highlight that a large number of studies in different locations are needed to comprehensively understand and accurately predict GHG emissions from peatlands.