Effects of peatland management on aquatic carbon concentrations and fluxes

[摘要] Direct land-to-atmosphere carbon exchange has been the primary focus inprevious studies of peatland disturbance and subsequent restoration.However, loss of carbon via the fluvial pathway is a significant term inpeatland carbon budgets and requires consideration to assess the overallimpact of restoration measures. This study aimed to determine the effect ofpeatland land management regime on aquatic carbon concentrations and fluxesin an area within the UK's largest tract of blanket bog, the Flow Country ofnorthern Scotland. Three sub-catchments were selected to represent peatland landmanagement types: non-drained, drained, and restoration (achieved throughdrain blocking and tree removal). Water samples were collected on afortnightly basis from September 2008 to August 2010 at six sampling sites,one located upstream and one downstream within each sub-catchment.Concentrations of dissolved organic carbon (DOC) were significantly lower for the upstream non-drainedsub-catchment compared to the drained sub-catchments, and there wasconsiderable variation in the speciation of aquatic carbon (DOC, particulate organic carbon (POC),CO 2 , and CH 4 ) across the monitoring sites, with dissolved gasconcentrations inversely correlated with catchment area and therebycontributing considerably more to total aquatic carbon in the smallerheadwater catchments. Significantly higher POC concentrations were observedin the restored sub-catchment most affected by tree removal. Aquatic carbonfluxes were highest from the drained catchments and lowest from thenon-drained catchments at 23.5 and 7.9 g C m −2  yr −1 , respectively,with variability between the upstream and downstream sites within eachcatchment being very low. It is clear from both the aquatic carbon concentrationand flux data that drainage has had a profound impact on the hydrologicaland biogeochemical functioning of the peatland. In the restorationcatchment, carbon export varied considerably, from 21.1 g C m −2  yr −1 at the upper site to 10.0 g C m −2  yr −1 at the lowersite, largely due to differences in runoff generation. As a result of thishydrological variability, it is difficult to make definitive conclusionsabout the impact of restoration on carbon fluxes, and further monitoring isneeded to corroborate the longer-term effects.

[学科分类] 大气科学