Sphagnum Restoration on Degraded Blanket and Raised Bogs in the UK Using Micropropagated Source Material: a Review of Progress
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Sphagnum restoration on degraded blanket and raised bogs in the UK using micropropagated source material: a review of progress S.J.M Caporn1, A.E. Rosenburgh1,2, A.T. Keightley1, S.L. Hinde1,3, J.L. Riggs1, M. Buckler4 and N.A. Wright5 1School of Science and the Environment, Manchester Metropolitan University, UK 2Department of Biosciences, Durham University, UK 3National Trust, Dark Peak Estate, Hope, Derbyshire, UK 4Moors for the Future Partnership, Moorland Centre, Fieldhead, Hope Valley, Derbyshire, UK 5Micropropagation Services (EM) Ltd., East Leake, Leicestershire, UK ___________________________________________________________________________________________ SUMMARY There is a growing demand for a supply of Sphagnum to re-introduce to degraded peatlands. However, available supplies of Sphagnum of the desired species are often limited. We describe the propagation of Sphagnum from vegetative material in sterile tissue culture and the introduction of juvenile mosses into the field. Sphagnum produced in the laboratory in three different forms (beads, gel and plugs) was introduced to different peatland surfaces on upland degraded blanket bog and lowland cut-over peatland in northern England. On degraded blanket bog, the establishment of mixed-species Sphagnum plugs was typically 99 % while the survival of beads was much lower, ranging from little above zero on bare eroding peat to a maximum of 12 % on stabilised peat surfaces. On lowland cut-over peatland, all trials took place on peat with an expanding cover of Eriophorum angustifolium and tested Sphagnum gel as well as beads and plugs. This work showed that survival and establishment of plugs was high (99 %) and greater than for beads. Sphagnum gel reached a cover of 95 % in two years. The vegetative micropropagation of Sphagnum offers an effective source of Sphagnum for re-introduction to degraded peatlands. KEY WORDS: BeadaMoss®, bog restoration, peatland, Sphagnum micropropagation _______________________________________________________________________________________ INTRODUCTION Rochefort 2017). Evidence from these trials typically reveals requirements for maintenance of a high water Sphagnum delivers the form and function of raised table and some form of protection against and blanket bogs, and its widespread dominance desiccation, e.g. straw mulch or nurse plants, to provides a suite of peatland ecosystem services facilitate successful Sphagnum establishment (Lindsay 2010, Rydin & Jeglum 2013). Degraded (Quinty & Rochefort 2003, Groeneveld et al. 2007). sites, where the Sphagnum cover has been lost due to Similar requirements are likely for the restoration of human interventions such as harvesting, peat Sphagnum cover on blanket bog which has been extraction, drainage, overgrazing, fire and air degraded through the action of various causes pollution are slow to recover without further human including overgrazing, accidental fire and air action (Quinty & Rochefort 2003). The return of pollution (Anderson et al. 2009). However, in the Sphagnum moss, by natural recovery or managed re- case of blanket bog, there are fewer published reports introduction, is an essential factor for repair of of successful Sphagnum application (Hinde et al. degraded ombrotrophic peatlands (Van Breemen 2010). It is also less certain whether there is an 1995, Rochefort 2000). The majority of published obligate requirement for a steady, high water table research on Sphagnum restoration has been because blanket bog occurs in areas of high conducted on lowland raised bogs following precipitation and cloud cover (Rydin & Jeglum 2013) commercial peat extraction, forestry plantation and so that moisture arriving from above may agriculture (e.g. Sliva & Pfadenhauer 1999, compensate for a poor supply of water from below. Rochefort et al. 2003, Haapalehto et al. 2011). Repair An early example of restoration of Sphagnum to of lowland cut-over peatland to Sphagnum- upland blanket bog in the UK was reported by dominated bog communities has been achieved after Ferguson & Lee (1983) who transplanted Sphagnum considerable human intervention at numerous into the degraded bog surface of the English southern locations in different parts of the world (Glatzel & Pennines in 1979. Their efforts met with only limited Mires and Peat, Volume 20 (2017/18), Article 09, 1–17, http://www.mires-and-peat.net/, ISSN 1819-754X © 2018 International Mire Conservation Group and International Peatland Society, DOI: 10.19189/MaP.2017.OMB.306 1 S.J.M. Caporn et al. SPHAGNUM RESTORATION USING MICROPROPAGATED SOURCE MATERIAL success initially (attributed to the high levels of (Leicestershire, United Kingdom). Full details of air pollution at the time); but better results were culture methods are not presented since this is recorded from the original transplants after 25 years commercially sensitive information. For each (Caporn et al. 2006), indicating good potential for species, 5–10 capitula were collected (with successful Sphagnum restoration into these upland permission) from one population (within an area of blanket bogs. 1 m2), causing very little damage to the donor The recent successful methods of Sphagnum Sphagnum colonies. The culture procedure started introduction to peatlands, whether for the purpose of with single fresh Sphagnum capitula which were restoration of damaged or degraded peatbog surfaces surface-sterilised and transferred to agar-based (Quinty & Rochefort 2003) or for Sphagnum culture medium under aseptic conditions using farming, as demonstrated in Canada (Pouliot et al. standard tissue culture methods (Murashige & Skoog 2015) and Germany (Gaudig et al. 2017) require a 1962). Cultures were raised at 20 ºC under moderate large supply of moss propagules (also known as lighting (50 µmol m-2 s-1 photosynthetically active diaspores) to be removed from a donor site and radiation (PAR), i.e. λ = 400–700 nm) provided by transported to the recipient location. In some parts of cool white fluorescent lamps. After approximately the world, particularly western Europe, there are ten weeks, when plants were around 20 mm in length, insufficient donor sites to provide the required they were sub-divided (capitula produce several new quantity of moss, since most of the Sphagnum-rich shoots) and transferred to fresh culture medium at locations are in conservation areas and many of these temperature 18 °C and irradiance 100 µmol m-2 s-1 are regulated under the EU Habitats Directive PAR. After a further nine weeks, Sphagnum plants (92/43/EEC). Even where Sphagnum can be legally were prepared for transfer to outdoor or greenhouse sourced without significant harm to donor sites, there growing-on conditions through the production of are potential problems of accidental transfer of pest either Sphagnum liquid gel (BeadaGel™), Sphagnum species and pathogens such as heather beetle plugs (BeadaHumok™) or solid gel beads (Lochmaea suturalis) (Scandrett & Gimingham (BeadaMoss®) (Figure 1). In this article, these 1991) and bulgy eye (Cryptosporidium baileyi) products are often referred to as Sphagnum gel, (Baines et al. 2014), as well as Sphagnum diseases Sphagnum plugs and Sphagnum beads, respectively. such as the parasitic fungus Lyophyllum palustre The Sphagnum gel is a suspension of whole plants of (Limpens et al. 2003). Furthermore, the length 5–25 mm in flowing hydro-colloidal consequences of deliberately transferring Sphagnum gelatinous medium. In contrast, the Sphagnum beads provenances from one region to another are not are composed of numerous (typically ten) smaller understood. Sphagnum plantlets/fragments, following cutting to Here, we report the production and field approximately 5 mm length, embedded in a more application of an alternative source of Sphagnum solid form of the same gel material. Both beads and material using standard tissue culture propagation gel were normally transferred to field locations methods, which addresses some of the challenges and within ten days of preparation. The Sphagnum plugs constraints outlined above. Starting with as little as a were produced by applying micropropagated single capitulum from a known provenance, Sphagnum gel to cylindrical peat blocks (36 mm Sphagnum is cultured under laboratory conditions to diameter × 60 mm height) and growing on in a produce a variety of propagule products in large glasshouse under natural daylight at a range of volumes, each adapted for application to peatland in temperatures depending on seasonal climate different conditions. Since 2008 we have conducted (minimum 10 ºC, maximum 35 ºC), misting with numerous independent trials involving application of rainwater to keep the moss surface moist. Typically, propagated Sphagnum to both cut-over lowland Sphagnum plugs were transferred to the field within raised bog and degraded upland blanket bog. This 4–6 months. The application rate of Sphagnum fresh article reviews a representative selection of these biomass was lowest for beads (8.8 g m-2), trials to demonstrate the success, pitfalls and future intermediate for gel (330 g m-2) and highest for plugs potential of this approach. (around 650 g m-2). In the research reported here, the Sphagnum beads were single-species except in Trial D, but the METHODS Sphagnum gel and plugs contained a mixture of the following eleven species (with proportions): Propagation and culture of Sphagnum S. capillifolium (Ehrh.) Hedw. (ssp. capillifolium) All trials used micropropagated Sphagnum 8–15 %, S. cuspidatum Ehrh. ex Hoffm. 8–15 %, produced by Micropropagation Services