Environmental effects of drainage, drain-blocking and prescribed vegetation burning in UK upland peatlands

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Peatlands are important ecosystems for carbon (C) storage, provision of water resources and biodiversity. UK blanket peats represent 10—15% of those found worldwide. While many peatlands continue to be managed through artificial drainage and vegetation burning, it has long been recognized that local habitats and ecological diversity are strongly influenced by these practices. This paper reviews the hydrological, physicochemical and ecological effects of three widespread UK peatland management practices, namely artificial drainage, drain-blocking and rotational heather burning. Drainage and burning of peat often lead to altered runoff regimes, oxidation of organic matter, changes to C, nitrogen (N) and phosphorus (P) cycling, and increased metal and suspended sediment concentrations in streams relative to intact peatlands. Although artificial drainage is now rarely implemented on UK upland peats, a great number of historical drains remain, thus drain-blocking is increasingly being applied to restore many peatlands. In contrast, recent increases in the intensity and extent of rotational heather burning may result in further changes to peatland ecosystems. Relatively little is known about the environmental effects of rotational heather burning compared with drainage and drain-blocking management, and for all three of these management techniques there is scarce information on river ecosystem response. We hypothesize some likely effects of basin-scale drainage, drain-blocking and heather burning on stream ecosystems and illustrate these with a schematic model. Such a holistic consideration of peatland river basins is particularly timely with respect to the implementation of the EU Water Framework Directive.