Net Primary Production And Biomass Of Peatland Vegetation In Shelburne Vermont PDF Download

Boreal peatlands in the Oil Sands regions of Alberta are subject to vast disturbances and pollution caused by the in situ oil and gas extraction industry. At the same time, peatlands are recognized as enormous carbon (C) storing ecosystems that need protection during times of enhanced greenhouse gas emissions and ongoing anthropogenically-caused global warming. Starting in 2015, the Alberta Government released new regulations that aim at the conservation and protection of peatlands following disturbance by in situ oil and gas infrastructure via the restoration of an "equivalent land capability". The obligatory ecological restoration aims at the reestablishment of primary peatland functions, such as peat accumulation and C sequestration. First trials to restore peatlands following in situ oil sands well pad disturbances started in the early 2000's and until this day little research on the success of the various restoration techniques has been done. The aim of this dissertation is therefore the evaluation of different peatland restoration techniques following in situ oil sands well pad disturbances, via the assessment of the restored peatland's vegetation communities and functions, in particular the peat accumulation potential and return of C sequestration. Three sub-objectives focussed on the development of peatland characteristic plant species, the plant organic matter production and decomposition, the biogeochemistry and carbon sequestration. The study took place seven to 10 years post-restoration. Research sites were two decommissioned in situ oil sands well pads located in the Peace River and Cold Lake Oil Sands regions in northern Alberta. For this study, we selected five restored peatland areas, one unrestored control area of an in situ well pad, and 28 undisturbed reference wetlands. The evaluation of the restoration techniques included the complete removal of the in situ well pad's construction materials (CR), the partial removal of the well pad's mineral fill to 15 cm (PR15) above the water table level (WTL), to 5 cm above the WTL (PR5), and to near the WTL of the adjacent undisturbed fen ecosystem (PR0). Revegetation happened either spontaneously via natural ingress or was managed by active planting of vascular species, in particular Carex aquatilis, Larix laricina, and Salix lutea. Throughout the two-year study period, we measured the abundance, diversity, and richness of emerging plant communities, the net primary productivity (NPP) and litter decay, as well as net ecosystem exchange (NEE) via carbon dioxide (CO2) exchange, and methane (CH4) emissions. Furthermore, we measured environmental factors, such as WTL, soil and water chemistry and nutrient concentrations. In CR, a shallow open water area had formed with mostly spontaneously colonizing floating aquatic species and marsh-like vegetation in the periphery. This type of vegetation was measured to be a C source, where CH4 was released via aerenchyma. Biomass production and peat accumulation was observed marginal, except in a floating brown moss carpet. As a result, CR was observed to have an enhanced global warming potential, due to the positive C balance, where more C was released to the atmosphere than was taken up by the pedosphere. At PR15 and PR5, which were subject to plant species introduction, we found the lowest species diversity and richness among restored peatlands. Too dry conditions, with low WTL below the surface, turned PR5 and PR15 into carbon sources with increased global warming potential, due to the release of CO2 to the atmosphere. High biomass production was neutralized by an equally high decay rate resulting in low peat accumulation potentials. There was a positive relationship between shrub cover and net carbon uptake. We observed PR0, which was spontaneously revegetated by natural migration of diaspores, to develop fen characteristic vegetation with the highest plant species diversity and richness compared to other restored areas. Either dominant bryophyte cover or shrub vegetation helped contribute to the greatest peat accumulation potential compared to the other study areas. The WTL at the surface was a significant factor for returning a C sink function in the same restored area. Results indicate that the benefit of the complete removal of a former in situ oil sands well pad is negligible, and that ecological peatland restoration can be achieved with the partial removal of the mineral fill. Also, hydrological connectivity to undisturbed adjacent fen ecosystems is the most important limiting factor for the development vegetation communities characteristic of peatlands and resume peat accumulation and C uptake. Furthermore, the physical proximity to the respective diaspore bank is believed to facilitate and accelerate spontaneous natural migration of diverse plant species even on a residual mineral soil. Active plant introduction did not prove to have significant effects on diversification and enrichment of peatland characteristic plant communities.