Micro-propagated Sphagnum introduction to a degraded lowland bog: photosynthesis, growth and gaseous carbon fluxes

Keightley, A. T. (2020) Micro-propagated Sphagnum introduction to a degraded lowland bog: photosynthesis, growth and gaseous carbon fluxes. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Degraded peatlands are significant sources of carbon greenhouse gases, and their recovery can make significant contributions to UK climate change mitigation responsibilities, as well as deliver biodiversity benefits to BAP priority habitats. Sphagnum mosses are key species for northern peatland formation, and re-introduction is seen as an essential factor in successful restoration, but natural sources are scarce and protected. Micropropagated Sphagnum moss products (BeadaMoss®) have been developed to provide the Sphagnum necessary for new acrotelm development, peatbog recovery and hence carbon greenhouse gas (CGHG) sequestration following degradation. However, the properties and performance of BeadaMoss® Sphagnum, now being produced on an industrial scale, have not been scientifically assessed. This study made a detailed investigation of the performance of BeadaMoss® Sphagnum and its potential for growth and CGHG sequestration under laboratory and field conditions. In the laboratory (Chapter 2), maximum photosynthesis (Pmax) rates, and the ratio of Pmax to respiration, of BeadaMoss® Sphagnum were higher than those of wild-sourced Sphagnum. There were positive relationships between Pmax and macronutrients levels, and BeadaMoss® Sphagnum Nitrogen content reached 30 mg g-1 with no signs of toxicity. There were few anatomical or morphological differences, but generally more chloroplasts were recorded in BeadaMoss® than wild-sourced Sphagnum. Productivity of 11 species of BeadaGel™ (strands of developing BeadaMoss® Sphagnum in a hydrocolloidal gel, applied to a substrate) as both individual species and in a commercial mix, were studied in indoor and outdoor conditions (Chapter 3). The Sphagnum developed many growth points and grew rapidly in indoor conditions especially, and species traits developed as expected, particularly outdoors. Some suggestions are made for further increasing productivity in the commercial mix. Ecosystem CGHG flux was measured using closed chambers at plot scale on a degraded lowland bog undergoing restoration with and without application of BeadaGel™ Sphagnum to areas of both mature and immature Eriophorum angustifolium (Chapter 4). iii Studies were conducted over two-years of contrasting weather patterns (September 2016 to August 2018). In year 1 there was a mean net CGHG uptake of -264.39 ± 368.95 g CO2e m-2 yr-1 (all vegetated monitoring points, assuming equal distribution), with progression from CGHG emission from bare peat to increasing CGHG uptake as vegetation matured. In year 2, gross photosynthesis reduced significantly during a summer drought but there was still a mean net CGHG uptake of -99.01 ± 339.59 g CO2e m-2 yr-1 , demonstrating some resilience to climate change scenarios in this early-stage restoration site, particularly with Sphagnum application. CGHG emission from bare peat (341.10 ± 75.47 g CO2e m-2 yr-1 ) showed the magnitude of avoided losses. Sphagnum introduction reduced E. angustifolium density within mature vegetation, and increased both E. angustifolium density and CGHG uptake within immature vegetation. Methane flux contributed significantly to CGHG emission but was not closely related to water table depth. A study of physical and chemical peat characteristics (Chapter 5) showed that the site had legacy effects from long-term degradation, reducing capacity for hydrological stability and resilience to anticipated climate changes, particularly more regular episodes of drought. In summary, BeadaMoss® materials showed potentially rapid proliferation, essential for surface moisture retention in the early stages of restoration and for promoting acrotelm development, and hence application is likely to deliver good outcomes for degraded lowland bog recovery and CGHG uptake.