What's in Store?: Interactive Effects of Warming, Nutrient- and Carbon-Limitation on Decomposition and Greenhouse Gas Production in Wetlands.

Wetlands store vast amounts of carbon(C) but also release C-based greenhouse gases (CH₄ & CO₂) leaving uncertainty for their function as sinks or sources.  Emissions are known to be temperature sensitive with colder, northern systems being more affected by warming than tropical or subtropical systems.  In this talk, we discuss the results from several warming studies of peat decomposition that help explain the warming response of C-based gas emissions in systems of differing climate, vegetation and nutrient status.  In general, warming increases organic C availability (both quantity and quality) leading to progressively more nutrient limitation at higher temperatures. Microbial C-use efficiency and biomass dictate the response of greenhouse gas production (respiration) with warming rate and organic matter quality as key variables.  Warming effects on enzyme expression and kinetics coincide with changes in microbial stoichiometry and was also highly dependent on warming rate. These findings have implications both for understanding gaseous C production in high temperature tropical and subtropical wetlands, as well as for improved models to predict greenhouse gas emission rates of colder region soils based on present and future temperatures.