Comparative photosynthetic capacity, respiration rates, and nutrient content of micropropagated and wild-sourced Sphagnum

Rapid, effective restoration of degraded peatlands is urgently needed to reduce their current high levels of carbon loss. Re-introduction of Sphagnum moss, along with re-wetting, is key to returning carbon sequestration and retention capabilities to northern degraded bogs. Micropropagated (BeadaMoss(R)) Sphagnum has already been applied in large quantities, and more is planned, for restoration projects in Britain and parts of Europe. Comparison with wild-sourced Sphagnum material is therefore pertinent to demonstrate its safety and suitability for wide-scale application. Six Sphagnum species of micropropagated and wild-sourced origin were studied: S. capillifolium, S. fallax, S. palustre, S. papillosum, S. medium/divinum and S. squarrosum. Micropropagated Sphagnum had significantly higher light-saturated photosynthesis (Pmax) rates, little colour expression, an open habit (shoots separated), higher numbers of chloroplasts, and more numerous, smaller shoot apices (capitula) than wild-sourced Sphagnum. Potentially, greater numbers of chloroplasts in micropropagated Sphagnum facilitate higher photosynthesis rates, driving rapid growth in early-stage plants, particularly in optimum moisture conditions. Pmax rates were associated with lower bulk density (mass/volume) and higher nutrient concentrations in tissues. Micropropagated Sphagnum, grown with additional nutrients, showed no sign of nutrient toxicity or limited P or K, despite a N content approaching 30 mg g-1 (well above the highest literature-reported concentration threshold), indicating its nutrient-demanding early growth stage. Ranking species according to their Pmax and respiration rates (expressed on a dry matter basis) found that S. squarrosum was the highest and S. medium/divinum was the lowest, in both micropropagated and wild-sourced Sphagnum. Micropropagated Sphagnum is similar in form to wild-sourced, can be propagated in large quantities, and due to high photosynthesis rates and absorption of nutrients, is likely to establish well on application to a site where re-wetting has already occurred, therefore making it highly beneficial for restoration of degraded bogs.