Prescribed burning, atmospheric pollution and grazing effects on peatland vegetation composition.
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.