Sphagnum mosses cultivated in outdoor nurseries yield efficient plant material for peatland restoration S. Hugron and L. Rochefort Peatland Ecology Research Group (PERG), Centre for Northern Studies (CEN), Université Laval, Québec, Canada _______________________________________________________________________________________ SUMMARY Sphagnum mosses are often reintroduced for peatland restoration or needed for the initiation of cultivation basins for Sphagnum farming. Finding Sphagnum dominated peatland where plant collection is permitted can be challenging and hampers peatland restoration in some regions. Theoretically, starting from small initial collections in natural areas, Sphagnum could be multiplied at Sphagnum cultivation sites and then be used as donor plant material for restoration. However, it is uncertain whether cultivated Sphagnum possesses the same regeneration capacity as moss fragments originating from natural peatlands. In this study we compared the establishment of Sphagnum mosses and peatland plant diversity on experimental plots that were revegetated with cultivated Sphagnum and Sphagnum originating from natural peatland. We found that reintroducing cultivated Sphagnum carpets of thickness > 5 cm and carpets collected from natural peatlands resulted in the same Sphagnum establishment. The cover of vascular plants and the diversity of peatland plants were similar in plots restored using cultivated Sphagnum and plots that were revegetated with plant material collected from natural peatland. If the cultivated plant material is to be used for restoration purposes, the donor site for initiating the Sphagnum cultivation site should contain a high peatland plant diversity. KEY WORDS: diaspores, donor site, paludiculture, seeding plant material, Sphagnum farming _______________________________________________________________________________________ INTRODUCTION field is variable (ranging from almost no survival to 99 %) depending on the form of micropropagated In the past 25 years, there has been a growing amount propagule used and the site conditions (Caporn et al. of research concerning bog restoration (Chimner et 2018). Another avenue is to cultivate Sphagnum al. 2017) and Sphagnum cultivation, also called outdoors in Sphagnum cultivation sites (Gaudig et al. Sphagnum farming (Gaudig et al. 2018). This 2014, Pouliot et al. 2015, Gaudig et al. 2017, Hoshi increasing interest in the reintroduction of Sphagnum 2017, Gaudig et al. 2018). Given the initial mosses translates into an increasing demand for availability of Sphagnum fragments to establish Sphagnum donor plant material. In countries like cultivation, outdoor Sphagnum farming is possible Canada, where peatlands are widespread and and has the potential to rapidly increase the abundant, collecting mosses from a natural peatland Sphagnum biomass, especially if water inputs and (donor site) is generally permitted. After plant outputs are controlled (Pouliot et al. 2015, Gaudig et collection, the Sphagnum remaining at donor sites is al. 2017). In Germany, cultivated Sphagnum has been expected to recover within ten years (Guêné- used as the donor plant material for setting up new Nanchen et al. 2018). However, in countries where cultivation basins and expanding the cultivation area peatlands are scarce and where Sphagnum species are of a Sphagnum farming site with optimised rare or legally protected, finding a donor site is more hydrology (Greta Gaudig, personal communication). challenging depending on the protection status To date, however, outdoor cultivated Sphagnum has (Caporn et al. 2018). never been rigorously tested as a donor plant material To cope with shortage of donor propagules, one for restoration purposes. The goal of the study research avenue is to micropropagate Sphagnum reported here was to answer the following questions: tissues in the laboratory (details of the method not 1) Does cultivated plant material possess the same disclosed; Caporn et al. 2018) or by axenic in vitro regeneration potential as material collected from a cultivation (Beike et al. 2015). This type of natural peatland? cultivation technique requires only very small quantities of source material and rapidly produces 2) At what stage is cultivated plant material ready to propagules that are free of potential diseases and be harvested? other plant diaspores. Establishment success in the 3) Does the use of cultivated plant material reduce Mires and Peat, Volume 20 (2017/18), Article 11, 1–6, http://www.mires-and-peat.net/, ISSN 1819-754X © 2018 International Mire Conservation Group and International Peatland Society, DOI: 10.19189/MaP.2018.OMB.358 1 S. Hugron & L. Rochefort SPHAGNUM FROM OUTDOOR NURSERIES FOR PEATLAND RESTORATION plant diversity in the restored sites, compared to the maximum thickness of moss carpet collected the use of donor plant material collected from a from the cultivation basins (about 13 cm in B8; natural peatland? Table 1). An area defined by a 0.5 m2 quadrat was 2 We expected cultivated plant material to possess the harvested for each EU (6 m ), resulting in an same regeneration potential as plant material introduction ratio of 1:12, as recommended to collected from a natural peatland, as soon as the practitioners for restoration (Quinty & Rochefort cultivated Sphagnum carpet reached the same 2003). The plant material was spread evenly across thickness as the layer of material collected from the the EU by hand, covered with wheat straw -1 natural peatland (~ 10 cm); and that the diversity of (3000 kg ha ), then anchored to the ground with a net. plots revegetated with cultivated plant material would be similar to that of plots revegetated with Monitoring Sphagnum carpets collected from a natural peatland. Establishment of the vegetation was evaluated three growing seasons after reintroduction of the plant material. Cover of non-vascular plants was evaluated METHODS in ten systematically distributed quadrats (25 × 25 cm) per EU, while cover of vascular plants was evaluated Study site in two (1 × 1 m) quadrats. All plant species were The experiment was carried out on a vacuum- identified to the lowest taxonomic level possible and extracted peatland in eastern Canada (New cover (%) was recorded. Brunswick; 47° 49' N, 64° 38' W). This region is subject to the Atlantic maritime climate, which is Statistical analyses relatively cool and humid. During the three years of One-way ANOVAs were performed to evaluate the the experiment, average air temperature was 5.1 °C effect of donor material origin on plant and average annual precipitation was 1298 mm establishment. The variables analysed were: mean (Environment Canada 2018). The experimental plots cover per EU of Sphagnum and vascular plants, and (= experimental units) were located on a rewetted plant α-diversity (total number of species). The portion of the peatland that was adjacent to a restored MIXED procedure of the SAS software package sector. The residual peat was ~ 45 cm deep with a von (SAS Statistical System Software, v. 9.4, SAS Post humification of H5, pH 3.3 and electrical Institute Inc., Cary, NC, USA) was used. conductivity 113 µS cm-1. Water table depth was not Homogeneity and normality of variances was monitored during the experiment, but repeated ensured by modelling the variance with the GROUP observations prior to implementation of the statement of the REPEATED function and degrees of experiment had shown that the hydrology of the freedom were adjusted accordingly. If significant experimental site was representative for sites that are differences were found between reintroduced plant used for peatland restoration after peat extraction. material origins (alpha = 0.01), a Dunnett test was performed to compare plant material originating from Experimental design the cultivation basin with that from the natural site The experiment was set up in a complete randomised (considered as a control). block design (to minimise the effect of a gentle slope across the experimental site), replicated six times. The area of each experimental unit (EU) was 6 m2 RESULTS and there were 36 EUs in total. Donor plant material, composed of Sphagnum mosses along with seeds and After three growing seasons, the establishment of rhizomes of other peatland plants, was harvested plant material originating from the older cultivation from six different donor sectors within the same basins B6 and B8 was similar to the establishment of peatland complex. Five of the donor sectors were plant material collected from the natural portion of cultivation basins of different ages (see Table 1 for the peatland. The moss carpet in these two cultivation characteristics of the cultivated donor material and basins exhibited characteristics that were close to Pouliot et al. (2015) for a detailed description of the those of moss carpets in natural peatlands (i.e. cultivation basins), while the sixth was an thickness ≥ 5 cm and completely covered by undisturbed portion of the peatland (NAT; Table 1). Sphagnum capitula; Table 1). On the other hand, the Donor vegetation (including vascular plants and true establishment of plant material originating from the mosses) was harvested by hand down to the residual younger basins B2, B3 and B4 was 4–12 times lower peat surface in the Sphagnum cultivation basins or, in than for plant material collected from natural the natural peatland, to a thickness corresponding to peatland (F = 81.5; p < 0.0001; Figure 1). The moss Mires and Peat, Volume 20 (2017/18), Article 11, 1–6, http://www.mires-and-peat.net/,