The impacts of prescribed moorland burning on water colour and dissolved organic carbon: A critical synthesis

Abstract

33Discolouration of natural surface waters due to the humic component of dissolved organic carbon 34 (DOC) is a costly problem for water supply companies. This paper reviews what is known about 35 the impacts of prescribed moorland vegetation burning on water colour. Relevant research has taken 36 place at three scales: laboratory experiments on peat cores, plot scale sampling of soil waters and 37 catchment scale sampling of stream waters. While laboratory studies suggest burning increases 38 colour production, the evidence from catchment and plot studies is contradictory. Plot studies 39 suggest colour production may decrease or remain unchanged following burning although there is 40 evidence for some transient changes. Catchment studies suggest prescribed moorland burning 41 causes stream water colour to increase, although in most cases the evidence is not clear cut since 42 most studies could not clearly disentangle the effects of burning from those of vegetation cover. The 43 differences in findings between plot and catchment studies may be explained by: i) the short-term 44 nature of some studies which do not measure long-term response and recovery times to burning; ii) 45 the lack of colour measurements from shallow soil depths which contribute more to streamflow than 46 soil water from deeper in the peat; and iii) the possibility of hydrological interactions occurring 47

Vegetation burning for game management in the UK uplands is increasing and overlaps spatially with soil carbon and protected areas

“…A growing evidence base highlights negative impacts of burning on deep peat for a range of ecosystem services including drinking water quality (Glaves et al, 2013;White et al, 2007), for example through elevated DOC contents (Clay et al, 2012;Holden et al, 2012). There is also evidence of both negative (Garnett et al, 2000;Worrall et al, 2010) and positive (Clay et al, 2010) impacts of burning on carbon storage and further research is needed on the impacts on overall carbon budgets.…”

At the nexus of fire, water and society

“…Denver spent $23 million USD to remove sediment from a critical water supply reservoir). The primary concern related to peatland burning is the potential to increase the release of DOC, particulate organic matter, suspended sediments, aluminium and iron [33,34,70,71]. The presence of DOC can lead to water discoloration [33,34] and the need for more chlorine to achieve adequate disinfection [72].…”

Calluna vulgaris canopy height and blanket peat CO2 flux: Implications for management

“…As the rotational period shortens the amount of newly 58 burned peat will increase as plots are being burned more regularly and this increase in the surface area 59 of newly burned peat will increase export of DOC. However, it was argued by Holden et al (2012) that it 60 may not necessarily be burning per se that leads to increased DOC, but the removal of vegetation, as 61 bare peat is associated with greater colour production than vegetated peat. A similar argument has also 62 been made with reference to methane fluxes where burning has no apparent impact on methane 63 uptake capacity on regularly burned (10 year cycle) blanket peat heath whereas complete heather 64 removal (without burning) uniformly decreased methanotroph populations (Chen et al 2008).…”