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Research article2013Peer reviewedOpen access

Simulation of six years of carbon fluxes for a sedge-dominated oligotrophic minerogenic peatland in Northern Sweden using the McGill Wetland Model (MWM)

Wu, Jianghua; Roulet, Nigel T.; Sagerfors, Jörgen; Nilsson, Mats

Abstract

Northern peatlands store similar to 30% of the global soil carbon, despite covering only 3% of the land. To understand the carbon balance of these systems and predict their response to changes in climate, robust and reliable models are needed. The McGill Wetland Model (MWM), originally developed to simulate the carbon dynamics of ombrotrophic bogs, was modified to simulate the CO2 biogeochemistry of sedge-dominated oligotrophic minerogenic peatlands, a prominent peatland type in boreal and subarctic landscapes. Three modifications were implemented: (1) a function to describe the impact of soil moisture on the optimal gross primary production, (2) a scheme to partition the peat profile into oxic and anoxic compartments based on the effective root depth as a function of daily sedge net primary production, and (3) a function to describe the fen moss water dynamics. The modified MWM was evaluated using eddy-covariance net ecosystem production (NEP) from Degero Stormyr in northern Sweden. The root mean square error for daily NEP was similar to 0.46g C m(-2) d(-1), and the index of agreement was 84%. This model adequately captures the magnitude and direction of the CO2 fluxes and simulates the seasonal and inter-annual variability reasonably well (r(2)>0.8). Sensitivity analysis confirms that specifically water table depth (WTD) and moss water content are key biogeochemical hydrology processes for the carbon biogeochemistry of a sedge-dominated oligotrophic minerogenic peatland. An increase of WTD by 15cm or air temperature by 3 degrees C could decrease NEP by up to 200% and make the peatland become a source of CO2.

Keywords

Oligotrophic minerogenic peatland; ecosystem modeling; carbon cycling; peatland; NEP; climate change; hydrology

Published in

Journal of Geophysical Research: Biogeosciences
2013, Volume: 118, number: 2, pages: 795-807
Publisher: AMER GEOPHYSICAL UNION