Talal Asif
Ph.D. student
Department of Phytology
Laval University

Supervised by:

Line Rochefort (Regular member)

Research project description

Development of a method for short-term suppression of peat decomposition through the strengthening of the enzymic latch

Introduction: Peatlands are unique ecosystems where the rate of production exceeds the rate of decomposition, leading to accumulation of organic matter (Moore et al., 2007). Pristine peatlands are water-saturated (strong anoxia) which reduces the microbial activity of the extracellular phenol oxidases allowing the build-up of phenolic compounds in the peat substrate. Phenolic compounds are complex and recalcitrant chemicals suppressing the activities of another set of extracellular enzymes, hydrolases, which are crucial agents in the process of organic matter breakdown and mineralization. The constraints imposed by the phenolic compounds are known as the “Enzymic latch” (Freeman, et al., 2001). However, in drained peatlands where there is an important decrease in the water table level (limited anoxia), it has been shown that the enzymic latch is open (Fenner and Freeman 2011). This allows the process of decomposition to occur unabated with the ultimate release of CO2 and other GHGs. Objectives: The main goal of this study is to develop a method to reduce the decomposition rate along with CO2 and CH4 emissions on drained peatlands through a better understanding of the “Enzymic latch” mechanisms. Study sites: In Eastern Quebec, study sites regroup old abandoned peatlands: Bois-des-Bel (BDB- abandoned since 1980) and Chemin-du-Lac (CDL - abandoned since 1990) and more recently abandoned peatlands: Verbois A (abandoned since 2017) and Verbois B (abandoned since 2013). Bois-des-Bel (BDB) peatland (47° 58′ N, 69° 43′ W) covers 189 ha, of which 11.5 ha were extracted for horticultural peat from 1972 to 1980. The pH of the peatland is 3.5. Chemin-du-Lac peatland (47°45’30’’N, 69°31’23’’W) encompass 3375 ha, it is classified as a ‘domed bog’ (National Wetlands Working Group, 1997), and 900 ha of this peatland have been vacuumed harvested for horticulture means. CDL has a pH of 5.2. Verbois A (47°50’02’’N, 69°26’23’’W) and Verbois B (47°49’41’’N, 69°26’32”W) peatlands cover an approximate area of 6.76 ha and 4.5 ha respectively with a pH of 3.8. Prior to the cessation of peat extraction activities, these peatlands were vacuum extracted by the Premier Tech Horticulture. Material and methods: A small-scale experiment in the lab will be conducted to compare the effect of different lignin products on suppression of peat decomposition. Then, the suitable lignin-based products will be selected (e.g., biochar, lignosulfate, primary and secondary sludges, cranberry leaves) and applied within multiple treatments in the selected experimental units in the post-extracted peatlands. CO2 exchanges will be measured using closed chamber technique. Concentration of CO2 will be measured using a portable infrared gas analyzer (IRGA). Concentration of CH4 will be measured using gas chromatographic technique. Water samples will be collected for phenolic concentration measurements in the laboratory. The activity of hydrolase enzymes will be measured using the protocol by Dunn et al. (2014). For microbial activity, peat samples will be collected and analyzed in collaboration with Dr. Kang’s lab at Yonsei University, South Korea. References: Dunn, C., Jones, T. G., Girard, A., & Freeman, C. (2014). Methodologies for Extracellular Enzyme Assays from Wetland Soils. Wetlands, 34(1), 9-17 Fenner, N.,

Research Site Coordinates

Scientific Communications

Asif, T., Naeem, I., Bu, Z.-J., Mallik, A., Ma, J.-Z., Rochefort, L., 2021. Litter mixing effects on decomposition in a peatland partially drained 30 years ago. <strong>Wetlands Ecology and Management</strong>, 29: 883-895. DOI: <a href="" target="_blank">10.1007/s11273-021-09818-4</a>.

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