Rotational vegetation burning effects on peatland stream ecosystems.
Rotational vegetation burning in peatlands is undertaken predominantly to increase habitat suitability and food availability for red grouse Lagopus lagopus (Linnaeus). Red grouse shooting contributes to the upland economy and is seen as a traditional leisure activity. However, there is concern that burning can have detrimental effects on peatland terrestrial and freshwater ecosystems. This study examined spatial and seasonal dynamics of stream physicochemistry and benthic macroinvertebrates from peatland sites that are managed via rotational vegetation burning and compared these with intact sites with no recent history of burning. Streams draining burned catchments were characterized by higher fine benthic particulate organic matter (FPOM), suspended sediment concentration (SSC), aluminium, iron and dissolved organic carbon than unburnt intact catchments. Anion concentrations were higher in intact catchments. There were significant differences in benthic macroinvertebrate richness, diversity and dominance, and community composition and functional feeding groups between burned and intact catchments, suggesting that land management had an effect on aquatic ecosystems. Higher SSC and FPOM in burned catchments were associated with lower abundance of some mayflies, stoneflies and caddis-flies and elevated abundance of some Diptera (Chironomidae and Simuliidae) larvae. Synthesis and applications. This study suggests that some aspects of peatland stream ecosystems are altered in catchments with rotational vegetation burning. Currently, there is much emphasis on the effects of rotational burning on peat carbon stores, but this study is the first to document the impacts on stream biota. Agencies with a remit covering upland freshwater ecosystem management might need to consider ways of reducing the extent of rotational vegetation burning to prevent effects on lotic ecosystems, and monitor whether macroinvertebrate assemblages subsequently shift back to a status similar to those in intact peatland streams. Fire occurs commonly on peatlands throughout the world, and our results suggest that trade-offs are needed to satisfy both economic and ecological facets of the combined social-ecological systems in such areas, especially where fire is implemented as a management tool.