From a boreal bog to an abandoned peatland pasture: the effect of agricultural management and abandonment on the greenhouse gas fluxes, carbon balance and radiative forcing of a boreal bog in western Newfoundland, Canada

• Main Author: Wang, Mei
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2017
• Subjects: Canada; Newfoundland
• Online Access: https://research.library.mun.ca/12948/; https://research.library.mun.ca/12948/1/thesis.pdf

Undisturbed peatlands generally act as a long-term carbon (C) sink and climate cooling. Agriculturally managed peatlands have been identified as hotspots for C and greenhouse gases (GHGs) emissions. However, the increased magnitude of C and GHGs emissions following agriculture management was found to be significantly variable, dependent on the management intensity, peatland initial conditions, cultivation species, time for plant regeneration and fertilization amount. Moreover, the knowledge of how agricultural management and abandonment affects GHGs fluxes is limited by insufficient direct comparisons of GHGs fluxes between undisturbed peatlands and agriculturally managed ones and failure to consider all three GHGs species. To bridge this gap, I conducted a study measuring the landscape-scale carbon dioxide (CO₂) and methane (CH₄) fluxes by eddy covariance and plot-scale N2O fluxes using static chamber technique in a boreal bog and an adjacent abandoned peatland pasture to determine and compare the controls on the temporal patterns of all GHGs fluxes and the effect of agricultural conversion and abandonment on the GHGs fluxes, the C balance and radiative forcing of a boreal bog in western Newfoundland, Canada. This study showed that the gross primary productivity (GPP) and ecosystem respiration (ER) of the abandoned peatland pasture was significantly higher than the counterparts at the bog. The between-site difference in GPP was mainly related to their different vegetation conditions, and the between-site ER difference was linked to different conditions of water table, substrate availability and autotrophic respiration. Overall, the abandoned peatland pasture was a stronger CO₂ sink than the bog. The abandoned peatland pasture was a smaller CH₄ source than the bog. CH₄ flux showed distinct diel and seasonal patterns at the bog but not at the abandoned peatland pasture. Subsurface soil temperature was the main control on CH₄ flux during the growing season but friction velocity became important in the non-growing ...