Sensitivity of Arctic Permafrost Carbon in Mackenzie River Basin Peatlands: An Incubation Experiment to Observe the Priming Effect

Abstract

The goal of this laboratory incubation experiment was to better understand the potential for priming effects to occur and alter carbon balance in carbon-rich peatland permafrost soils within the Mackenzie River Basin, Canada along a north-south transect. Geographical effects on soil processes can potentially be seen in the specific responses and vulnerabilities of these soils across latitude. Temperature, precipitation, and permafrost SOM quality are some examples of ecosystem characteristics that are in part determined by location; all influence microbial activity driving carbon cycling processes (Treat et al., 2014). Assuming that characteristics of organic matter affect the magnitude of the priming effect, expected differences in carbon quality between the northern and southern sites may exhibit different potential for the priming effect. Hartley et al. (2010) found that low nutrient availability, especially nitrogen, produces the most pronounced priming effect when labile compounds were added to the soil. Regions with poor nutrient availability will exhibit more of a priming effect due to microbial mining for necessary nutrients to support new microbial growth (Hartley et al., 2010; Kuzyakov et al., 2000; Kuzyakov, 2010). Assuming the microbial communities are similar in structure between the permafrost peatland sites used in this experiment, microbial decomposition will not be controlled by community composition, but instead by limiting factors specific to the soil ecosystem of each site. The geographic factors directing priming potentials of permafrost soils in the Mackenzie River Basin will consist of site specific variations caused by latitudinal effects.