Impact of raw water characteristics on

More recently, studies from a range of UNC669 and soil types have identified significant relationships between plant functional type (PFT) and the production of DOC and water colour, in both the laboratory (Cleveland et al., 2004 and Wickland et al., 2007) and the field (Pellerin et al., 2010). This relationship is thought to occur because the physical and chemical properties of litter, which vary between PFT, have a strong influence on the rate of decomposition and therefore DOC production (Hobbie et al., 2000). Blanket peatland vegetation communities are comprised of a range of PFT types and consequently vegetation composition is likely to influence the amount of DOC and colour in water draining from blanket peatlands. This hypothesis is supported by laboratory peat manipulation studies (Vestgarden and Austnes, 2009), with bare peat producing more colour when saturated than other cover types while under dry conditions Calluna-dominated cores doubled their colour production (Millar, 2008). A preliminary field study by Armstrong et al. (2012) found that soil water in ditched areas of blanket peatland dominated by Calluna sp. had greater concentrations of DOC than those ditched areas dominated by Sphagnum sp. and sedges. However, an understanding of the extent to which a catchment\'s vegetation composition influences the level of colour and concentration of DOC in stream water is lacking. Although plot and laboratory scale studies are of value in understanding drivers of DOC and water colour production, blanket peatland vegetation is typically highly heterogeneous, and multiple drivers may contribute towards the amount of DOC and water colour observed within stream waters at a catchment scale. Consequently, in order to establish the dominant drivers of DOC and colour in peatland stream waters and to establish an understanding of controls of value to land managers, vegetation must be investigated across multiple catchments.