Growing Sphagnum FOREWORD

Growing Sphagnum

FOREWORD

S. Glatzel1 and L. Rochefort2

1University of Vienna, Austria and 2Université Laval, Québec, Canada ______

In many places, especially in Europe, the collection The challenges of growing Sphagnum are of Sphagnum moss and the extraction of low- manifold. The propagation of diaspores is especially humification (fibric) Sphagnum peat from peatlands important because, in many cases, the protected is no longer possible because these materials have status of Sphagnum is an obstacle to finding become too scarce. Moreover, the favoured land uses propagule material in sufficient quantities. Then, for peatlands in both good and degraded condition horticultural and agronomic aspects of producing a nowadays include their protection and restoration for crop are not straightforward (Gaudig et al. 2014, biodiversity conservation as well as rewetting to Pouliot et al. 2015) because we are dealing with a preserve the terrestrial carbon store. In restoring plant that lacks roots and whose leaves respond Sphagnum peatlands for nature conservation and directly to the environment on account of their single- other ecosystem services, an important goal is the layered cell structure. Sphagnum tends to be out- recovery of their natural vegetation. This may not competed by other plants in regions with abundant happen spontaneously for a variety of reasons (e.g. nitrogen supply (Limpens et al. 2011), such as parts Poulin et al. 2005) so that intervention is often of central Europe that are heavily affected by required, especially to establish growing Sphagnum atmospheric nitrogen deposition. Difficult legal (Figure 1) on bare peat surfaces. issues arise and traditional conservationist views are Sphagnum fibre is an indispensable raw material challenged when grassland is converted to ‘cropland’ for numerous valuable products, and demand to produce Sphagnum, and when Red List species are continues to grow worldwide despite the increasing to be harvested. Consequently, research is needed on availability and industry uptake of peat alternatives topics ranging from the biology, propagation and (Caron & Rochefort 2013). For an in-depth cultivation of Sphagnum to irrigation engineering, explanation of what makes Sphagnum so good as a economics and the revision of land tenure law before constituent of horticultural growing media and an a full-scale Sphagnum-based agro-industry can be account of where the market is expanding, see the developed. review by Caron et al. (2015). However, concerned consumers and environmental groups campaign for The ‘Growing Sphagnum’ Special Volume of more sustainable production methods because the Mires and Peat brings together research spanning the material for this application is mostly obtained by whole of the spectrum outlined above, in 13 articles. extraction of so-called ‘white’ or ‘blond’ peat (also Silvan et al. (2017) describe a method tested in marketed as ‘peat moss’ by some suppliers). Finland by which Sphagnum biomass is harvested Undecomposed Sphagnum is used as ‘floral moss’ directly from mires. Early results indicate that there for orchid propagation, as packaging material (e.g. is potential for sustainable operation of the approach for fish and orchids), for specialised products like in a manner that is largely comparable with biodegradable flowerpots, for green walls or roof sustainable forestry management. Another gardening, and as ‘seed’ material for peatland sustainable production approach is proposed by restoration. To meet all of these demands, we need to Gaudig et al. (2017) for Germany, whereby formerly develop new techniques for producing Sphagnum extracted bogs can be converted to the climate- fibre. Considering the fact that Sphagnum moss will friendly land use of Sphagnum farming. During the have lost 90 % of its biomass by the time it eventually first large-scale trial in Europe, they measured a becomes peat (Clymo 1984), Sphagnum fibre is production of 19.5 tonnes per hectare of accumulated obtained more efficiently by harvesting moss than by dry biomass after nine years. peat extraction. Recently, the practice of growing When harvesting Sphagnum from semi-natural or Sphagnum, known as ‘Sphagnum paludiculture’ or natural peatlands, its regrowth needs to be ensured. ‘Sphagnum farming’, has been tested in several Krebs et al. (2018) compare Sphagnum regrowth on locations. Sphagnum farming is defined as the sites in (cool) temperate Germany and warm sustainable production of non-decomposed temperate Georgia, and find no pronounced Sphagnum biomass on a cyclic and renewable basis. difference between these two climatic zones.

Mires and Peat, Volume 20 (2017/18), Article 00, 1–4, http://www.mires-and-peat.net/, ISSN 1819-754X © 2017 International Mire Conservation Group and International Peatland Society. DOI: 10.19189/MaP.2017.OMB.276 1 S. Glatzel & L. Rochefort GROWING SPHAGNUM (FOREWORD)

Figure 1. Some example species of growing Sphagnum moss. Top left: a mixture of Sphagnum balticum (the more-slender species, reddish colour) and Sphagnum papillosum (more robust, ochre colour); top right: Sphagnum fimbriatum - note the insectivorous sundew (Drosera sp.) plant rooted in the moss carpet; bottom left: Sphagnum majus; bottom right: Sphagnum lindbergii. In the two right-hand images, the spherical objects are spore capsules. Photos: Gilles Ayotte.

In relation to optimising Sphagnum growth higher C sequestration efficiency by minimising the conditions on extracted bogs, Guêné-Nanchen et al. area occupied by irrigation ditches. Interestingly, this (2017) question the expected importance of vascular idea has been tested on the other side of the Atlantic plants competing with the developing moss carpet. by Brown et al. (2017), who showed that CO2 uptake When the dominant vascular plant invading the was indeed maximised when the irrigation system Sphagnum farming system has a graminoid form consisted of perforated sub-surface drainage tiles. (e.g. a sedge) it appears that no ‘weed’ control is These authors recommend that, to maximise CO2 needed because the plant produces minimal amounts uptake, the irrigation system design should confine of litter. the range of water table fluctuations to ± 7.5 cm of It is important to assess the greenhouse gas release the seasonal mean. and carbon sequestration potential of Sphagnum From another management viewpoint, the farming as a new land use strategy for peatlands, mechanical harvesting of farmed Sphagnum biomass because the drained and fertilised peatlands that are in a wetland environment is challenging. Kumar used for traditional farming have been identified as (2017) discusses the results of various trials that hotspots of agricultural GHG emissions. Günther et continue through the post-harvest processing of al. (2017) report that establishing a Sphagnum farm Sphagnum material to produce professional growing on bog that was formerly under grassland utilised for media constituents, and concludes that mechanical low-intensity agriculture reduced its GHG emissions, treatments do not impact negatively on the quality of and suggest that the fields could be designed for even the eventual product.

Mires and Peat, Volume 20 (2017/18), Article 00, 1–4, http://www.mires-and-peat.net/, ISSN 1819-754X © 2017 International Mire Conservation Group and International Peatland Society. DOI: 10.19189/MaP.2017.OMB.276 2 S. Glatzel & L. Rochefort GROWING SPHAGNUM (FOREWORD)

When producing Sphagnum biomass, economic REFERENCES aspects are critical. Is Sphagnum farming lucrative? What needs to be done to make it economically viable Brown, C.M., Strack, M. & Price, J.S. (2017) The in different legislative contexts, with and without effects of water management on the CO2 uptake agricultural and environmentally motivated of Sphagnum moss in a reclaimed peatland. Mires subsidies? Wichmann et al. (2017) present a first and Peat, 20(05), 1–15. assessment of the economics of establishing Brust, K., Krebs, M., Wahren, A., Gaudig, G. & commercial Sphagnum cultures on areas belonging to Joosten, H. (2018) The water balance of a different land use categories. Sphagnum farming site in north-west Germany. The collection and propagation of suitable Mires and Peat, 20(10), 1–12. Sphagnum species is a challenging prerequisite when Caporn, S.J.M., Rosenburgh, A.E., Keightley, A.T., setting up sites for cultivation. Due to the widely Hinde, S.L., Riggs, J.L., Buckler, M. & Wright, varying environmental settings of Sphagnum N.A. (2018) Sphagnum restoration on degraded cultivation sites, many different approaches are being blanket and raised bogs in the UK using tested. Hugron & Rochefort (2018) compare the micropropagated source material: a review of regeneration capacity on outdoor experimental plots progress. Mires and Peat, 20(09), 1–17. of cultivated Sphagnum and Sphagnum harvested Caron, J. & Rochefort, L. (2013) Use of peat in from natural peatland. When donor plants are very growing media: State of the art on industrial and rare, Sphagnum propagated from sterile tissue scientific efforts envisioning sustainability. Acta cultures may be a viable alternative. Caporn et al. Horticulturae, 982, 15–22. (2018) describe this ‘micropropagation’ process and Caron, J., Price, J.S. & Rochefort, L. 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Hoshi (2017) compares the growth progress. Mires and Peat, 13(08), 1–11. of Sphagnum capitula established in colonies of Gaudig, G., Krebs, M. & Joosten, H. (2017) different sizes on floating rafts at mountain and urban Sphagnum farming on cut-over bog in NW sites in south-west Japan. Germany: Long-term studies on Sphagnum In their closing contribution, Gaudig et al. (2018) growth. Mires and Peat, 20(04), 1–19. provide a comprehensive review of current Gaudig, G., Krebs, M., Prager, A., Wichmann, S. and knowledge relating to the entire sequence of 30 others (2018) Sphagnum farming from species Sphagnum farming operations, from the selection of selection to the production of growing media: a suitable seed material and the cultivation process to review. Mires and Peat, 20(13), 1–30. post-harvesting applications of Sphagnum biomass in Guêné-Nanchen, M., Pouliot, R., Hugron, S. & horticultural growing media. Rochefort, L. (2017) Effect of repeated mowing to reduce graminoid plant cover on the moss The contents of this Special Volume show that carpet at a Sphagnum farm in North America. some progress towards Sphagnum-based agriculture Mires and Peat, 20(06), 1–12. has been made since 2004, but several questions still Günther, A., Jurasinski, G., Albrecht, K., Gaudig, G., need answers. Ecological considerations that will be Krebs, M. & Glatzel, S. (2017) Greenhouse gas important when producing a crop on peat bog soil balance of an establishing Sphagnum culture on a include the export of dissolved organic carbon (DOC) former bog grassland in Germany. Mires and Peat, and phosphorus (P) to downstream water bodies, as 20(02), 1–16. well as biodiversity. To obtain a complete picture of Hoshi, Y. (2017) Sphagnum growth in floating all economic and ecological aspects, it is important to cultures: Effect of planting design. Mires and conduct life cycle analyses as well as local case Peat, 20(08), 1–10. studies. The results may help to disentangle the Hugron, S. & Rochefort, L. (2018) Sphagnum mosses complex relationships between the multiple facets of cultivated in outdoor nurseries yield efficient Sphagnum biomass production mentioned above, and plant material for peatland restoration. Mires and to balance the inevitable trade-offs. Peat, 20(11), 1–6.

Mires and Peat, Volume 20 (2017/18), Article 00, 1–4, http://www.mires-and-peat.net/, ISSN 1819-754X © 2017 International Mire Conservation Group and International Peatland Society. DOI: 10.19189/MaP.2017.OMB.276 3 S. Glatzel & L. Rochefort GROWING SPHAGNUM (FOREWORD)

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Volume Editors’ contact information:

1Professor Stephan Glatzel, Department of Geography and Regional Research, University of Vienna, Austria. Email: [email protected]

2Professor Line Rochefort, Department of Plant Sciences, Université Laval, Québec, Canada. Email: [email protected]