$\mathrm{CO}_2$ Fluxes from Peat in Boreal Mires under Varying Temperature and Moisture Conditions

Jouko Silvola, Jukka Alm, Urpo Ahlholm, Hannu Nykanen and Pertti J. Martikainen
Journal of Ecology
Vol. 84, No. 2 (Apr., 1996), pp. 219-228
DOI: 10.2307/2261357
Stable URL: http://www.jstor.org/stable/2261357
Page Count: 10

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Abstract

1 $CO_2$ emissions in boreal peatlands were measured during two seasons on various mire site types representing different nutrient statuses and water tables. In order to examine the long term effects of water table draw-down on the $CO_2$ fluxes, the sites also included 25-50-year-old drainages. 2 On virgin sites the lowest $CO_2$ fluxes were measured at ombrotrophic sites dominated by Sphagnum fuscum (78-127 mg $CO_2 m^{-2} h^{-1}$ at 12 $^\deg C$, 60-200 g $CO_2$-C $m^{-2}$ year $^{-1}$) and the highest $CO_2$ fluxes were at ombrotrophic sites with abundant understorey vegetation (183-259 mg $CO_2 m^{-2} h^{-1}$ at 12 $^\deg C$, 290-340 g $CO_2$-C $m^{-2}$ year $^{-1}$). 3 Lowering of the water table by 1 cm increased $CO_2$ fluxes by an average of 7.1 mg $CO_2 m^{-2} h^{-1}$ at 12 $^\deg C$ and 9.5 g $CO_2$-C $m^{-2}$ year$^{-1}$. In some cases the effect of ditches on the water table, and correspondingly on $CO_2$ fluxes, was small. However, effective draining caused $\approx 100\tt\%$ increase in $CO_2$ fluxes. Drainages had higher $CO_2$ fluxes compared with virgin subsites at the same temperature and water table. 4 The effect of temperature on $CO_2$ fluxes depended on the water table, the average $Q_{10}$ value being 2.9 with water tables of 0-20 cm and 2.0 with water tables below 20 cm. 5 $CO_2$ fluxes are compared with primary production figures, and peat carbon stores and the carbon balance in changing climate are discussed.

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