EXMOOR SHALLOW PEAT TOXIC FLORA EXMOOR SHALLOW PEAT Bog asphodel distribution following peatland METHANE EMISSIONS restoration on Exmoor How does restoration age, vegetation and water

depth impact methane (CH4) emissions from § Post-restoration bog asphodel () continues to restored mires within Exmoor National Park? survive but has not spread significantly. his study1 investigated the gaseous Figure 33 A cluster of bog asphodel (Narthecium § Re-establishment of mire vegetation associated with wetter conditions § Bog asphodel contributes up to 20 % forage value in transitional bog ossifragum) flowers on Aclands July 2017. carbon (C) balance of restored habitats. serves as a useful indicator for increased CH4 emissions, which in turn mires in Exmoor National Park indicates that restored mires on Exmoor are returning to a more natural Tusing a restoration age sequence of state. sites (from 6 months to ~7 years post-

og asphodel (Narthecium of transitional blanket bog habitat, § Annual CH4 emissions from restored sites on Exmoor are low, even restoration), as well as unrestored and ossifragum) is a common comprising up to 18 % of forage after ~7 years post-restoration, suggesting that the timeline for mire semi-natural sites. component of blanket bog value (Figure 35). This contribution restoration to a more natural state is likely to exceed 10 years. Increased cover of associated with Bvegetation, seen as patches of bright may continue throughout the season, wetter conditions (e.g., Sphagnum moss) green fleshy leaves growing from and its contribution to habitat crude and higher mean annual water levels patches of rhizomes (underground protein value may even increase in were linked to increased methane (CH ) emissions stems), with conspicuous yellow the autumn. 4 1 and site restoration status (Figure 36 and 37). Higher flowers in early summer (Figure CH fluxes indicate the presence of anaerobic (oxygen 33). The leaves and especially the Figure 35 Bog asphodel (Narthecium 4 ossifragum) forage quality at Aclands deficient) microbial communities where microbial CH4 flowers are readily eaten by grazing generation (methanogenesis) occurs as a biproduct livestock but contain toxins that can and Roosthitchen. Aclands (70 % bog asphodel cover) shows a steady in the breakdown of organic matter. Therefore, CH cause acute photosensitization and 4 15-17 % contribution on 5 measures emissions, and thus methanogenesis, is an indicator that fatal liver and kidney disease in lambs of quality, in both seasons. There was anaerobic conditions are becoming more dominant 2,3 Figure 34 Post-restoration change in and calves . This research aimed to less bog asphodel at Roosthitchen within the peat soil due to increased water saturation. address concerns that restoration (18 - 30 %) and this contributes 5 – spread of bog asphodel (Narthecium 10 % on 5 measures of quality, less in ossifragum) over 18 sites on Exmoor. The Restoration activities on Exmoor seek to increase would increase the occurrence of x represents mean change (4.5±33.8 % 6 autumn than spring. Energy represents water saturation levels within the peat soils, and bog asphodel and consequently metabolisable energy (MJ). to 11 years post-restoration). livestock fatalities. therefore CH4 emissions can be viewed as a sign of restoration success. Figure 37 shows that vegetation The height varies from 10 to data, particularly percentage cover of mire species 40 cm depending on the density associated with wetter habitats, could provide a of the surrounding vegetation and valuable tool for assessing CH4 emissions and site possibly on early season grazing. conditions of restored mires. Growth and flowering rates vary Figure 36 Mean annual water table position and percentage cover of significantly year on year and may Sphagnum moss for study sites ranging from unrestored and newly Semi-natural sites (those with little or no impact from account for the annual variations in restored (yellow) through to semi-natural sites/wet controls (blue). drainage and peat cutting) from this study showed toxicity seen in northern UK and similar properties (i.e. gas emission balance, depth . profiles of dissolved gases and stable C isotope analysis) to natural peat soils elsewhere in Bog asphodel has a life history and . However, the semi-natural sites strategy that enables it to thrive in from this study are likely still in a state of transition, conditions intolerable to many plants also supported by vegetation survey data. Recovering i.e. very wet, acidic and nutrient peat soils can transition through a stage of higher poor soils4. It spreads only slowly CH4 emissions before lowering as the coverage of gas by rhizoidal growth and does not conductive (aerenchymatous) plant species (e.g. cotton rely on seed dispersal for survival. It REFERENCES grasses (Eriophorum spp.)) decreases, and conditions does however persist in the most within the peat soil stabilise. challenging conditions. Analysis of The appendices are available to view at www.exeter.ac.uk/creww/research/casestudies/ its distribution at individual sites and miresproject over 18 restored sites on Exmoor 1. Summerfield RJ. (1974). Narthecium ossifragum(L.)Huds.J. Ecol. 62(1), 325–339. suggests it continues to survive 2. Angell, J., & Ross, T. (2011). Suspected bog asphodel (Narthecium ossifragum) toxicity in cattle REFERENCES following peatland restoration, but in North Wales. Veterinary Record, 169(4). The appendices are available to view has not spread significantly in the 3. Pollock, M. L., Wishart, H., Holland, J. P., Malone, F. E., & Waterhouse, A. (2015). Photosensitisation at www.exeter.ac.uk/creww/research/ short-term (<11 years) (Figure of livestock grazing Narthecium ossifragum: Current knowledge and future directions. casestudies/miresproject 34), as predicted by its life history Veterinary Journal, 206(3), 275–283. 5 1. Mcaleer, A. Carbon dioxide and strategy . 4. Grime, J. P. (1979). Plant strategies and vegetation processes. John Wiley & Sons, Ltd, Chichester, Figure 37 Relationship between annual methane (CH4) flux (g CH4 -2m a-1) methane exchange from restored mires New York, Brisbane, Toronto. and percentage (%) cover of wet mire plant species (e.g. Sphagnum moss) in Exmoor National Park. (University of Bog asphodel leaves and flowers are 5. Hand, AMS. (2020) Does the restoration of shallow marginal peatlands impact on the at sample sites. Flux estimates are based upon scaled monthly or bimonthly Bristol, 2016). a relatively nutritious component distribution and abundance of Bog asphodel? (Unpublished MRes thesis). University of Exeter measurements from June 2013 to June 2014.

34 Mires On The Moors Science and Evidence Report 35