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Prescribed burning of vegetation is a land management approach that can be used to prevent or reduce the risk of wildfires yet burns can escape and be an ignition source for wildfires. In Scotland, muirburn is a form of prescribed burning used to encourage new growth of heather for grouse and livestock. Future regulation aims to mitigate potential negative impacts of muirburn on biodiversity, peat carbon stocks and wildfire risk. In this study, we assessed the spatial co-occurrence of muirburn and wildfires across Scotland. Evidence of muirburn was quantified using high-resolution aerial imagery from 2018 and wildfire occurrence was a composite of satellite and aerial detection covering 2015 to 2020. Fires were mapped on to dominant vegetation habitat types (acid grasslands, heather grasslands, heather heathlands, and peatbogs) and peat soil. Overall, 96 % of the total wildfire area occurred outside moorlands managed by muirburn, with wildfires covering 1.1 % of total moorland area. Heather grasslands, peatbogs and habitats on peat soils had a greater proportional area of wildfires than other moorland habitats and habitats on non-peat soils. In contrast, heather heathlands with non-peat soils had a greater proportional area of muirburn. We suggest the limited co-occurrence of muirburn and wildfires, may be due to fuel load reduction following muirburns, but may arise due to wildfire prevention strategies on estates and/or lower occurrence of recreational caused wildfires. In addition to muirburn regulation, our findings emphasise the need for policy, management, awareness and education outside of muirburn areas to reduce the risk of wildfires. • Mapped muirburn (prescribed burning) and wildfire area across Scottish moorlands • Overall, 96 % wildfire area occurs outside of moorland managed by muirburn • Between 2015 and 2020 wildfires covered 1.1 % of the moorland land area • Moorland vegetation and soil types differed in proneness to muirburn and wildfire [ABSTRACT FROM AUTHOR]

Burning for habitat management is globally widespread. Burning over carbon-rich soils is a global environmental concern due to the potential contribution to climate change. In the UK, upland heath and blanket bog, so-called 'moorland', often overlies carbon-rich soils, and has internationally important conservation value, but is burned as management for gamebird shooting and to a lesser extent for livestock grazing. There is little detailed information on the spatial extent or temporal trends in burning across the UK. This hinders formulation of policies for sustainable management, given that the practice is potentially detrimental for soil carbon storage, water quality and habitat condition. Using remotely sensed data, we mapped burning for gamebird management across c45 000 km 2 of the UK. Burning occurred across 8551 1-km squares, a third of the burned squares in Scotland and England were on peat ≥ 0.5 m in depth, and the proportion of moorland burned within squares peaked at peat depths of 1–2 m. Burning was detected within 55% of Special Areas of Conservation and 63% of Special Protection Areas that were assessed, and the proportion of moorland burned was significantly higher inside sites than on comparable squares outside protected areas. The annual numbers of burns increased from 2001 to 2011 irrespective of peat depth. The spatial overlap of burning with peat and protected areas and the increasing number of burns require urgent attention, for the development of policies for sustainable management and reversal of damage to ecosystem services in the UK uplands. [ABSTRACT FROM AUTHOR]

Highlights: [•] Moorland vegetation on peat is subject to both prescribed burning and wildfire. [•] Propagule banks were measured at two moorlands to assess regeneration potential. [•] Deep litter accumulated seeds and prevented transfer to underlying peat. [•] Long-rotation burns favoured Calluna vulgaris and Sphagnum propagule frequency. [•] We advise burning at two rotations; short for conserving diversity in vegetation and long for conserving propagule banks. [ABSTRACT FROM AUTHOR]

Abstract: European lowland heaths have declined by up to 80% due to land use change and lack of management. There has been considerable research into the restoration of this threatened habitat. However, long-term outcomes of restoration are poorly understood, especially in situations where past agricultural land use imposes severe constraints on community re-assembly. In 1989 a large-scale experiment was established to examine the effectiveness of five treatments to restore heathland on formerly productive grassland: (i) natural regeneration; (ii) herbicide application to facilitate regeneration; (iii) cultivation and application of seed-rich heathland vegetation; (iv) soil removal and incorporation of heathland topsoil; and (v) heathland translocation. After 17years the pH of the unamended agricultural soil remained significantly higher than that of the adjacent heathland. All treatments showed different trajectories of vegetation change in the long-term. Natural colonisation by heathland species was slow due to seed limitation, resulting in formation of an acid grassland community. Heathland community assembly was not facilitated by destruction of the initial grassland with herbicide. Incorporation of topsoil had an intermediate effect on pH reduction. This may explain the subsequent failure of the plant community to assemble in the anticipated proportions, and the dominance of leguminous scrub species (Ulex spp.). Turf translocation was effective in reducing pH to the required range and restoring the heathland community in the long-term. However, this technique should only be considered as a means of ‘rescue’ when habitat destruction is otherwise unavoidable. The only practical and sustainable means of increasing heathland extent on former farmland is the application of seed-bearing vegetation cut as part of routine management. However, this technique needs refining in order to establish the full range of characteristic heathland species. [Copyright &y& Elsevier]

Plant communities in the low-alpine zone are exposed to relatively high levels of nitrogen (N) deposition compared to surrounding lowland areas and this has the potential to alter community composition and ecosystem function. N content and nitrogen: phosphorus (P) ratio of plant tissues have been used as bio-monitors of N deposition impacts in sub-alpine systems but their suitability in alpine habitats is unknown. We investigated spatial variation in N content and N:P in Calluna vulgaris and Racomitrium lanuginosum in low-alpine heathlands across Scotland and related this to nitrogen deposition, climate and soil chemistry. N content in C. vulgaris and R. lanuginosum were not well predicted by N deposition estimates and it appears that altitude and climate also have strong influences on plant chemistry which must be accounted for before using these parameters as bio-indicators of deposition. N:P ratios in C. vulgaris suggested that most sites are currently co-limited by N and P or P limited. The degree of P limitation was strongly related to P content of the soil and hence to underlying rock type. We suggest that this high degree of co-limitation may be the result of accumulated long term N deposition in mountain regions. Vegetation on soils with low P content and strong P limitation on growth is least likely to sequester N inputs in additional biomass production and so may be the most vulnerable to N saturation and breakthrough of N into surface waters. [Copyright &y& Elsevier]

Abstract: Heathlands are endangered by both atmospheric nutrient deposition and natural succession. High-intensity management measures are considered necessary, as low-intensity measures (e.g. mowing, prescribed burning) are not able to compensate for atmospheric nutrient loads. Choppering (i.e. the near-complete removal of the O-layer) has several advantages over sod-cutting, including less waste material, faster vegetation recovery and lower costs. This raises the question addressed in this study as to the extent to which choppering and sod-cutting affect nutrient budgets in dry heathlands. We compared the quantities of N, Ca, K, Mg, and P removed by choppering and sod-cutting in the Lueneburg Heath (NW Germany). Nutrient balances were calculated by analysing atmospheric inputs, elevated leaching rates following management, and output due to the removal of above-ground biomass and humus horizons. Nutrient loss was particularly high after removal of O- and A-horizons. In contrast, increased leaching after management was of minor importance for nutrient budgets. Although considerably more nutrients were removed by sod-cutting than by choppering (e.g. N: 1712/1008kgha−1), nutrient output by choppering was still sufficient to compensate for 60.7 years of net N-input. Choppering was able to remove more N per volume unit than sod-cutting due to higher N-contents in the organic layer than in the A-horizon. For this reason, choppering is more economical than sod-cutting and, thus, should be considered the preferable method at sites not dominated by Molinia caerulea. A combination of high-intensity measures with prescribed burning would appear to be suitable as this would ensure more selective removal of N. [Copyright &y& Elsevier]

Abstract: A change in the vegetation of UK moorland from Calluna vulgaris-dominated heath to Molinia caerulea- or Nardus stricta-dominated grassland is frequently deemed undesirable on economic and biodiversity grounds. Moorland vegetation restoration is an increasingly practiced management option. However there has been little research on the effectiveness of such management for aiding the restoration of other aspects of moorland biodiversity such as associated insect populations. We sampled Hemiptera and Lepidoptera assemblages from restored, degraded and C. vulgaris-dominated (target) moorland at eight restoration sites in England and Scotland. Vegetation assemblages and additional environmental variables were sampled at the same locations. Vegetation restoration aided the reassembly of moorland insects to a variable extent. Hemiptera restoration success was greatest at mechanically restored sites dominated by C. vulgaris. In addition to treatment, latitude best explained variation in the Hemiptera assemblage. A range of plant species, all either dwarf shrubs or graminoids, acted as further determinants. Lepidoptera restoration success was correlated most closely with the success of restoring the full diversity of the vegetation assemblage and was highest at sites restored by grazing control. The results demonstrate that vegetation restoration brings wider biodiversity benefits and that the form these take may depend on the restoration method used and consequent characteristics of the resultant vegetation assemblage. [Copyright &y& Elsevier]

Abstract: We investigated ways of optimising the establishment of Calluna vulgaris-dominated heathland vegetation following removal of pines from afforested heathland using a randomised block experiment. Removal of the litter layer, or both the litter and humic layers, resulted in a higher initial establishment rate of C. vulgaris compared to in the control plots. The effect of adding heathland clippings suggested that the rate of establishment of C. vulgaris was limited by seed availability in plots from which both the litter and humic layers had been removed, but not in those from which just the litter layer had been removed. Removal of both the litter and humic layers did, though, result in a long-term reduction in the depth of the humic layer, a lower loss-on-ignition and lower level of nitrate and total nitrogen compared to in the control plots. The optimal method for establishing heathland vegetation at a site will depend on: (1) whether there is a viable seedbank of C. vulgaris and other desirable heathland species present; (2) the importance of quickly establishing a high cover of desirable heathland species; (3) the likely long-term effects of soil nitrogen levels on the maintenance of C. vulgaris dominance; (4) the practicality of removing and disposing of the litter and humus layers. [Copyright &y& Elsevier]

In the Mediterranean region, cycles of controlled burning combined with continuous grazing appear to have been an effective tool for maintaining isolated Calluna vulgaris heathlands in the form in which they occur in many places in the Atlantic region. Changes in land use and management of the mosaic of extensively exploited heathland and associated grassland over recent decades, such as bringing land into cultivation followed by its abandonment and the prohibition of fires has resulted in a process of transformation into new shrub communities with lower biodiversity. In the Mediterranean region, these changes are similar to those described in the Atlantic area, but encroachment occurs faster and could lead ultimately to afforestation by Mediterranean woodland.In a study area of 300 ha of heathland in the Spanish Mediterranean basin (specifically, in the Montseny Natural Park and Biosphere Reserve), comparison of present and former vegetation showed that shrub cover increased from 15% in 1967 to 32% in 2000. Broom (Cytisus scoparius) was the main invasive species in abandoned crop fields, whereas Mediterranean holm oak forest (Quercus ilex) increased by 18%. The surface area of fernlands doubled and C. vulgaris heathlands decreased from 35% to just 9% during the same period. Intermixed grasslands also decreased moderately and progressively from 4% to 3%.It seems probable that cycles of fires are more important in terms of shrub control and biodiversity conservation than continuous grazing alone, even at a high rate of stocking (four small ruminants per hectare per year). This encroachment process throws into relief the role that isolated habitats can play as a monitor of land use changes. [Copyright &y& Elsevier]

We compared the effectiveness of topsoil removal and deep ploughing of an agriculturally improved grass field at creating suitable soil conditions for establishment of heathland vegetation. We then carried out a randomised replicated experiment involving combinations of topsoil removal, addition of heathland clippings and addition of Pteridium aquilinum litter and Pinus mulch to determine their effects on soil conditions and heathland establishment. The topsoil treatment had significantly lower concentrations of extractable P in its upper soil compared to the control plots. Both the topsoil removal and deep ploughing treatments had significantly higher pH in their upper soil compared to the control plots. Heathland vegetation established on all plots involving topsoil removal and addition of heathland clippings (with or without addition of P. aquilinum or Pinus mulch), despite soil pH in these plots being higher (5.9–6.8) than that generally recognised as being necessary for establishment of heathland vegetation. [Copyright &y& Elsevier]

A field experiment was carried out to investigate the impact of four different management treatments on the response of Calluna-dominated heathland to nitrogen additions of 0 or 30 kg ha-1 yr-1 at a lowland heath in Surrey, England. Post-management Calluna regeneration, growth and canopy development were significantly affected by both the form of management and by nitrogen addition. The effect of nitrogen on shoot growth was lower, in absolute terms, in those plots which had undergone more intensive management treatments. Seedling establishment was higher in plots which received a simulated accidental burn treatment, reflecting the greater proportion of bare ground and the high degree of physical disturbance associated with this treatment. Invasion by Deschampsia seedlings was increased by nitrogen addition, particularly in simulated accidental burn plots. In the long term, the need to maintain a low nutrient environment to favour Calluna dominance, particularly in the face of elevated nitrogen deposition, favours the use of managements which result in the export of a significant proportion of the organic nitrogen stores. However, further study is required to ensure that initial enhancement of seedling invasion by grass and other species, associated with these more intense managements, does not outweigh the long term benefits of associated nutrient removal. [Copyright &y& Elsevier]

Molinia encroachment is considered a major threat to moorland and heathland conservation in Europe, and there is a need to develop management strategies to control Molinia and restore Calluna moorland. Here we combined weed control and restoration treatments into an integrated land management strategy (ILMS) to provide a more sympathetic approach than previous prescriptions. We applied the following treatments in factorial combination to a Molinia-dominated moorland in the Yorkshire Dales: grazing (ESA prescription level versus no grazing), cutting (0, 1, 2 and 3 cuts), ±application of a graminicide and ±Calluna brash addition. The response of the vegetation was assessed for four years. These data were analyzed using a combination of univariate and multivariate analysis of variance based on constrained ordinations but combined with bivariate standard deviational ellipses. This combined approach was extremely useful in identifying trends in this complex dataset.The only treatment that had consistent effects in the univariate analysis of variance was cutting, where there was increased bare ground, reduced vegetation height, increased species diversity and reduced Molinia cover. Cutting three times had the greatest effect, maintaining a reduced Molinia cover over four years. The multivariate analysis showed that there were important community level interactions. Grazing generally produced vegetation which had a greater moorland species complement. Where grazing was restricted the vegetation had a greater component of Molinia and other acid grassland species. The most effective treatment was the grazed plots, cut thrice, which maintained a low Molinia cover for longest and had less variation in moorland species in the fourth year. Graminicide and brash application had marginal effects on species composition, but the best plots were those given herbicide alone, or in combination with brash addition.These results contrast with other studies, where non-selective herbicide treatment and Calluna addition were required to obtain Molinia control and Calluna regeneration. However, great variation has been found between sites, and managers should be prepared to tailor ILMS for their own site. This is likely to require a knowledge of the initial floristic composition, seed banks and experimentation. [Copyright &y& Elsevier]

Upland heather moors are high priority biotopes for conservation in Britain, but are under threat from a number of sources. One such threat is a change from a vegetation dominated by dwarf shrubs, mainly Calluna vulgaris, to a grassland dominated by Molinia caerulea. Restoration of a dwarf shrub community has proved problematic with studies showing that herbicide use may be necessary to control Molinia. Previously the non-selective herbicide, glyphosate, has been recommended, but this herbicide may damage Calluna and other moorland species severely. Here, we tested a range of selective herbicides (graminicides) for use in an herbicide-based conservation strategy under field conditions. Two selective herbicides, propaquizafop and quizalofop-ethyl, gave a short-term check to Molinia and another, cycloxydim, provided a reduction for at least 1 year, but this effect disappeared after 3 years. Damage to Calluna was less than that caused by glyphosate, and the selective herbicides had little effect on other moorland species present. Our findings suggest that selective herbicides have a potential role in reducing Molinia during moorland restoration, although follow-up applications, and appropriate moorland management, will also be needed. [Copyright &y& Elsevier]

The dwarf shrub heather Calluna vulgaris is an important component of the UK landscape, with value for amenity, nature conservation and animal production. A model, called “HeathMod”, is described, which investigates the impact of grazing on upland heather. It combines an empirical model of production with a simple process-based model of grazing impacts. Validation from short-term studies in the literature indicated that the model predicts grazing impacts well, although more studies of grazing impacts are required to confirm the model’s accuracy. Analysis of the model allowed derivation of a simple general formula for predicting sustainable levels of grazing, given knowledge of local site productivity. Predicted levels of sustainable grazing were lower than previous estimates, mainly because the model predicts the long-term impacts of sustained grazing. Application of the model is most appropriate in areas where heather is in mixed-age stands, because there is inadequate information available to model interactions between grazing and degeneration in even-aged stands of heather. [Copyright &y& Elsevier]