A Novel Approach to Assess the Degradability of Soil Organic Matter in Wetlands
The northern cold region wetlands are impacted by the increased air and soil temperatures which affects the soil biogeochemical processes and accelerates soil organic matter (SOM) degradation. Enhanced SOM degradation converts wetlands from carbon sinks to sources. Therefore, understanding the biogeochemical processes underlying SOM degradation is critical for informing management strategies that can limit wetland carbon losses. The response of SOM degradation to changing environmental conditions depends on the intrinsic degradability of the SOM, where hydrolysis is a crucial first step by which soil microbes convert the macromolecular SOM into monomers readily available for microbial consumption. We used Isothermal microcalorimetry (calorimeter) technique to assess the potential degradability of SOM by measuring heat flows exhibited at 25oC, induced by adding hydrolytic enzymes (glucosidase and glucosaminidase) to soil samples collected from a bog, fen, swamp, marsh, and riparian wetlands across Ontario, Canada. Our calorimeter experiment results and total energy allocated for hydrolysis of SOM decomposition showed that the riparian wetland soils exhibited the highest total heat with glucosidase and glucosaminidase (1.56 ± 0.63 and 2.18 ± 0.03 J g-1 soil), followed by fen (-0.23 ± 0.15 and -3.36 ± 0.06 J g-1 soil), marsh (-3.2 ± 0.07 and -0.20 ± 0.02 J g-1), swamp (-0.08 ± 0.06 and -0.59 ± 0.19 J g-1 soil) and bog (-0.50 ± 0.03 and -0.46 ± 0.03 J g-1 soil, respectively). In this presentation, the calorimeter will be showcased as a novel experimental approach to investigate SOM degradation in different wetland types under variable environmental conditions.