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Understanding fire impacts on peatland vegetation can inform management to support function and prevent degradation of these important ecosystems. However, time since burn, interval between burns and number of past burns all have the potential to modify impacts. Grazing regime may also affect vegetation directly or via an interaction with burning. We used new, comprehensive survey data from a hillslope-scale field experiment initiated in 1954 to investigate the effects of burning and grazing treatments on Sphagnum. Historical data were consulted to aid interpretation of the results. The unburned reference and the most frequently burned (10-year rotation) treatments had greater Sphagnum abundance and hummock height than intermediate treatments (20-year rotation and no-burn since 1954). Abundance of the most common individual species (S. capillifolium, S. subnitens and S. papillosum) followed similar patterns. Light grazing had no impact on Sphagnum-related variables, nor did it interact with the burning treatments.These results suggest that in some cases fire has a negative impact on Sphagnum, and this can persist for several decades. However, fire return interval and other factors such as atmospheric pollution may alter effects, and in some cases Sphagnum abundance may recover. Fire severity and site specific conditions may also influence effects, so we advise consideration of these factors, and caution when using fire as a management tool on peatlands where Sphagnum is considered desirable. [ABSTRACT FROM AUTHOR]

Abstract: Peatlands are valued for ecosystem services including carbon storage, water provision and biodiversity. However, there are concerns about the impacts of land management and pollution on peatland vegetation and function. We investigated how prescribed vegetation burning, atmospheric pollution and grazing are related to vegetation communities and cover of four key taxa (Sphagnum spp., Calluna vulgaris, Eriophorum vaginatum and Campylopus introflexus) using two datasets from a total of 2,013 plots across 95 peatland sites in the UK. Non‐metric multidimensional scaling and permutational multivariate analysis of variance showed differences in vegetation community composition between burned and unburned plots at regional and national scales. Analysis showed that burned sites had less Sphagnum and greater C. vulgaris cover on a national scale. On a regional scale, plots burned between 2 and 10 years ago had greater cover of invasive moss C. introflexus and less E. vaginatum than unburned sites. Livestock presence was associated with less Sphagnum and C. vulgaris, while atmospheric pollution was associated with less Sphagnum, but greater C. introflexus cover, and appeared to have more impact on burned sites. Synthesis and applications. Burning, grazing and atmospheric pollution are associated with peatland vegetation composition and cover of key species, including Sphagnum. We suggest that, to promote cover of peat‐forming species, peatlands should not be routinely burned or heavily grazed. Current or historical atmospheric pollution may hinder peat‐forming species, particularly on burned sites. [ABSTRACT FROM AUTHOR]