Annual carbon balance of a peatland 10 yr following restoration

[摘要] Undisturbed peatlands represent long-term net sinks of carbon; however, peatextraction converts these systems into large and persistent sources ofgreenhouse gases. Although rewetting and restoration following peatextraction have taken place over the last several decades, very few studieshave investigated the longer term impact of this restoration on peatlandcarbon balance. We determined the annual carbon balance of a formerhorticulturally-extracted peatland restored 10 yr prior to the study andcompared these values to the carbon balance measured at neighboringunrestored and natural sites. Carbon dioxide (CO₂) and methane(CH₄) fluxes were measured using the chamber technique biweekly duringthe growing season from May to October 2010 and three times over the winterperiod. Dissolved organic carbon (DOC) export was measured from remnantditches in the unrestored and restored sites. During the growing season therestored site had greater uptake of CO₂ than the natural site whenphoton flux density was greater than 1000 μmol m⁻² s⁻¹,while the unrestored site remained a source of CO₂. Ecosystemrespiration was similar between natural and restored sites, which were bothsignificantly lower than the unrestored site. Methane flux remained low atthe restored site except from open water pools, created as part ofrestoration, and remnant ditches. Export of DOC during the growing seasonwas 5.0 and 28.8 g m⁻² from the restored and unrestored sites,respectively. Due to dry conditions during the study year all sites acted asnet carbon sources with annual balance of the natural, restored andunrestored sites of 250.7, 148.0 and 546.6 g C m⁻², respectively.Although hydrological conditions and vegetation community at the restoredsite remained intermediate between natural and unrestored conditions,peatland restoration resulted in a large reduction in annual carbon lossfrom the system resulting in a carbon balance more similar to a naturalpeatland.

[学科分类] 地球化学与岩石