Effects of rotational prescribed burning and sheep grazing on moorland plant communities: Results from a 60‐year intervention experiment

Abstract The effect of prescribed burning for conservation management of plant communities is controversial for moorlands growing on peat. These ecosystems provide many services that may be damaged by fire, hence it is important to fully assess its impact on all aspects of ecosystem structure and function experimentally over relatively long time‐scales. This paper describes change in community composition, major plant species, and plant functional types on moorland on peat in upland Britain over 60 years subject to 3 burning treatments after an initial burn in 1954/1955: no further burn and burning at 10‐ and 20‐year intervals (all ± sheep grazing). Data were analysed using multivariate and univariate methods. Vegetation composition and individual species abundance reflected the degree of disturbance. The least disturbed was dominated by Calluna vulgaris and pleurocarpous mosses, whereas the most disturbed treatment (burned every 10 years) had greater Eriophorum vaginatum, Sphagnum spp., acrocarpous mosses, liverworts, and lichens. The 20‐year treatment was intermediate in response disturbance. Repeated burning increased species abundance‐weighted Ellenberg values for moisture, reaction, light through time, and fertility; the exception was the 10‐year rotation for fertility. These confirm that prescribed burning is not deleterious to peat‐forming species (Eriophorum spp. and Sphagnum spp.), indeed these species were found in greater abundance in frequently burned treatments. It also confirms that a no‐burn policy will lead to increasing dominance of C. vulgaris, a flammable, fire‐adapted shrub, which increases summer wildfire risk. These results inform conservation management policy for moorland vegetation growing on peat; for this site, a 20‐year prescribed burning rotation is recommended.