Carbon fluxes in forested bog margins along a human impact gradient: Could vegetation structure be used as an indicator of peat carbon emissions?

Bog ecosystems are sensitive to anthropogenic disturbance, including drainage and air pollution. Carbon (C) balance measurements to determine the effect of disturbance on bog functioning are laborious; therefore reliable proxies for C fluxes that could facilitate upscaling from single studies to a larger scale would be valuable. We measured peat CO2 emissions (R s), CH4 efflux and vegetation characteristics in four bog areas that formed a gradient from pristine to severely disturbed peatlands, affected by drainage, peat mining, alkaline air pollution and underground oil-shale mining. We expected that sites experiencing higher human impact (i.e., the vegetation was more distinct from that of a natural bog) would have higher R s and lower CH4 emissions, but differences in peat C emissions between the most disturbed and pristine sites were not significant. Growing period median R s ranged from 0.5 to 2.2 g C m−2 day−1 for our plots; methane emissions, measured from July to December were an order of magnitude lower, ranging from −5.9 to 126.7 mg C m−2 day−1. R s and CH4 emissions were primarily determined by water table depth, as was tree stand productivity. Therefore, stand structural parameters could potentially be good indicators of soil C emissions from poorly drained forested bogs.