Greenhouse Gas Fluxes from Peatland Pools

Abstract:

Peatlands contain around one third of the global soil carbon (C) stock. Understanding the processes in peatland C cycling, and in particular those involved in the release of the greenhouse gases (GHGs) CO₂ and CH₄ to the atmosphere, is a current research priority. Natural open-water pools are a common feature of many peatlands, and previous research suggests pools can be strong sources of atmospheric GHGs, particularly CH₄, and thus have the potential to play an important role in global radiative forcing. The area of open-water in peatlands is rapidly expanding in a warming Arctic (e.g. Walter et al., 2007) while artificially created pools are becoming more commonplace in the recent drive to restore the hydrological functioning of drained peatlands by blocking ditches.

We present the results of >2 years of comprehensive field monitoring from pool complexes in the Flow Country of northern Scotland, the largest expanse (c.4000 km²) of blanket bog in Europe. Concentrations and fluxes of CO₂ and CH₄ are presented from 12 intensively monitored pools and the adjacent terrestrial surface. We examined both natural (n = 6) and artificial (n = 6) pools, which allowed us to quantify how pools created during restoration compare to undisturbed sites. C and hydrology budgets were determined for the study pools and the adjacent terrestrial surface. Dissolved concentrations of GHGs ranged from 0.08−4.68 mg CO₂-C L^-1 and 0.01−731 µg CH₄-C L^-1 in natural pools, and 0.29−10.38 mg CO₂-C L^-1 and 0.04−239 µg CH₄-C L^-1 in artificial pools. GHG fluxes from natural pool surfaces ranged between -2.47−653 mg CH₄ m^-2 d^-1 and -31.7−14.8 g CO₂ m^-2 d^-1. Artificial pool GHG fluxes were -8.19−581 mg CH₄ m^-2 d^-1 and -7.66−34.9 g CO₂ m^-2 d^-1. We provide more accurate GHG budgets for peatlands with natural pool complexes by considering their relative importance at the landscape-scale, and outline the potential effect on GHG fluxes when creating artificial pools during peatland restoration activities.

WALTER, K. M., SMITH, L. C. & CHAPIN, F. S. 2007. Methane bubbling from northern lakes: present and future contributions to the global methane budget. Philosophical Transactions of the Royal Society A, 365, 1657-1676.