Does prescribed burning on peat soils influence DOC concentrations in soil and runoff waters? Results from a 10 year chronosequence

SummaryPrescribed burning of moorland, heathland and blanket bog vegetation on peatlands in the UK is a contentious issue. Given the large carbon store in these peatlands, concern has been raised over land management and its effect on the carbon dynamics of peat ecosystems. In particular the spatial and temporal link between burning and concentrations of dissolved organic carbon (DOC) in waters draining these catchments has received particular attention. This study investigates water colour and DOC concentrations in soil pore water and runoff water at the plot-scale over a chronosequence of burn ages. Results from this study show that there is an elevated water colour in the few years immediately following burning but that this is not matched by a rise in DOC concentration. Therefore we propose that burning appears to affect the composition of the DOC rather than the absolute DOC concentration. This study also highlights that in some cases the use of water colour as a proxy for DOC concentration should be treated with caution.

► We examined DOC concentrations from a chronosequence of prescribed burning sites.
► Elevated water colour occurs on the youngest burns.
► However, DOC concentrations are not significantly elevated in recent burns.
► Burning appears to alter the composition of DOC rather than absolute concentration.
► The use of water colour may not always be a good proxy for DOC concentration.