Methane dynamics of recolonized cutover minerotrophic peatland: Implications for restoration

In North America, mulching of vacuum-harvested sites combined with blocking of the drainage system is widely used for peatland restoration to accelerate Sphagnum establishment. However, peat extraction in fen peatlands or exposure of deeper minerotrophic peat layers results in soil chemistry that is less suitable for re-establishment of Sphagnum moss. In this situation, restoration of plant species characteristic of minerotrophic peatlands is desirable to return the site to a carbon accumulating system. In these cases, it may be worthwhile to maintain spontaneously revegetating species as part of restoration if they provide desirable ecosystem functions. We studied the role of six spontaneously recolonizing vegetation communities for methane (CH4) emissions and pore water CH4 concentration for two growing seasons (2008 and 2009) at an abandoned minerotrophic peatland in southeastern Quebec. We then compared the results with bare peat and adjacent natural fen vegetation. Communities dominated by Eriophorum vaginatum, Carex aquatilis and Typha latifolia had CH4 flux an order of magnitude greater than other cutover vegetation types and natural sites. In contrast, Scirpus atrocinctus and Equisetum arvense had CH4 emission rates lower than natural hollow vegetation. We found seasonal average water table and vegetation volume had significant correlation with CH4 flux. Water table and soil temperature were significantly correlated with CH4 flux at plots where the water table was near or above the surface. Pore water CH4 concentration suggests that CH4 is being produced at the cutover peatland and that low measured fluxes likely result from substantial oxidation of CH4 in the unsaturated zone. Understanding ecosystem functions of spontaneously recolonizing species on cutover fens can be used to help make decisions about the inclusion of these communities for future restoration measures.