Response of Methane Fluxes to Temperature in Wetland Ecosystems: Consistent?

Abstract:

A recent publication suggests that there is a consistent temperature dependency of methane fluxes across ecosystems and scales. Strong correlations between methane flux and ecosystem temperature have been reported in numerous studies over the last three decades. However, while the correlation is high, even when combining data for many different ecosystems and scales, it does necessarily follow that the relationship in each ecosystem or at each scale are the same. A robust measure for ‘consistency’ would be to show that the parameters among the flux-temperature relationship parameters (i.e. slope and intercept) for each ecosystem and scale are not statistical different for different. Examining the statistical parameters of this relationship across numerous wetlands (one ecosystem type) show there is little consistency – the form of the function is universal but the application of the function is not. For example, across many northern peatland, while the slope of the relationship between flux and temperature are somewhat similar the intercepts are very different. These differences have been attributed to structural differences in the ecosystems – i.e. plant communities, and environmental conditions such as moisture content and nutrient availability. Peatlands that are being influenced by climate change, particularly those associated with thawing permafrost, the slope of the functional relationship between methane and temperature changes as the plant community structure and ecosystem productivity change. Also the time scales over which methane emission and ecosystem production correlate vary depending on the plant communities involved. The distinction between a generalized association between methane and temperature and a consistent function that could be used across ecosystems and scale is important for the simulation of methane emissions.