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Understanding the controls on carbon dioxide (CO2) exchange within saline boreal fens, appropriate natural analogs for landscape reclamation in areas affected by salinization in the Athabasca Oil Sands Region, can provide insights into the biogeochemical and carbon sink functioning of constructed wetlands under saline conditions. Hence, this study aims to assess net ecosystem exchange (NEE), ecosystem respiration (R), and gross ecosystem productivity (GEP) of peatland and open-water areas within a saline boreal fen near Fort McMurray (Alberta, Canada) to determine environmental controls on CO2 fluxes using community-scale CO2 measurements along a salinity gradient. Strong positive correlations between NEE, GEP, leaf area index within peatland, and between GEP and vegetation density within open-water areas (ponds) were observed, demonstrating the importance of vegetation properties for carbon uptake. Strong negative correlations were found between NEE, GEP, R and water table depth and electrical conductivity within peatland. In contrast, GEP and R were positively correlated with phosphate concentrations in ponds, and electrical conductivity had no effect on CO2 fluxes within ponds. In peatlands, links between CO2 exchange and environmental factors were influenced by microtopography, and complex relationships between NEE, GEP, R and environmental variables were observed within depressions. [ABSTRACT FROM AUTHOR]

An understanding of the main controls on carbon accumulation in naturally saline peatlands can be useful for furthering peatland reclamation in the Athabasca Oil Sands Region where salinization complicates construction of sustainable peatland ecosystems. As such, the long-term apparent rate of carbon accumulation (LARCA) within a naturally saline fen situated near Fort McMurray, Alberta was studied using two peat cores. Changes in LARCA in less saline part of the fen coincide with water table fluctuations and seem not to be affected by low salinity (soil EC <5 mS cm−1). The highest LARCA values were associated with wet conditions; however, prolonged inundations coupled with high salinity (soil EC >10 mS cm−1) appear to have had a negative effect on LARCA. In the more saline part, salinity seem to have a notable effect on LARCA - hydrology links. Mean LARCA of the site (19.7 g−2 yr.−1) is lower than in western continental fens. The northern less saline part of the fen (soil EC <5 mS cm−1) has LARCA of 29.67 g−2 yr.−1 that is close to LARCA in continental fens, but LARCA in the southern part (soil EC >10 mS cm−1) is considerably lower (9.79 g−2 yr.−1). [ABSTRACT FROM AUTHOR]

Reports that after 30 years of abandonment, a block-cut peatland near Cacouna, Quebec, Canada, has naturally regenerated Sphagnum mosses on < 10% of its area, typical for these disturbed systems. How distinct hydrologic conditions were observed where Sphagnum has successfully recolonized, providing a basis for establishing thresholds that can be targeted by peatland restoration managers.

Early attempts at peatland restoration have been aimed mostly at rewetting the peat, which alone has proven inadequate to ensure good regeneration of Sphagnum mosses. Sphagnum mosses can be actively reintroduced by scattering Sphagnum fragments (diaspores) on bare peat surfaces and by sheltering them against desiccation. The present study aims at refining the restoration techniques to reintroduce Sphagnum where the surface conditions of cutover peatlands are too harsh for natural Sphagnum establishment. The objective is to increase local moisture conditions of the peat by reprofiling the surface to invert the camber created during drainage operations. Sphagnum diaspores were spread in the concavity. Reprofiling fields increased Sphagnum establishment compared to control sites. The addition of two plastic sheets on the edge of the field reduced evaporation and directed precipitation towards the middle of the field. When they were combined with reprofiling, there was a further increase in the establishment success of Sphagnum. [ABSTRACT FROM AUTHOR]

Exploitation of peatlands results in the degradation of hydrophysical conditions suitable for the re-establishment of peat-forming vegetation, notably Sphagnum mosses. Regeneration of peat-forming mosses necessitates a high and stable water table. The objective of this studywas to evaluate the performance of open water reservoirs constructedto improve the hydrologic conditions required for growth of Sphagnum. A section of abandoned peatland, where former drainage ditches havebeen blocked, was treated by excavating reservoir ditches at 3-, 5-,and 8-m intervals to increase the local water storage. The colonization of Sphagnum fuscum and S. angustifolium diaspores scattered on the experimental baulks between the reservoir ditches was measured. Results indicate that water storage increased at the experimental site. The water table was higher and more stable, with an average maximum depth of 0.46 m at the rewetted site compared to 0.55 m at the controlsite. The volumetric moisture content of the surface peat was improved by rewetting, showing an average of 62% compared to 55% at the control site. Negative soil water tension at the -0.1 m depth was ameliorated at the experimental sites and nearly eliminated where 5-m experimental ditch-reservoir spacing was employed. Sphagnum establishment was successful on all experimental baulks, showing a higher percentage cover where soil moisture was more readily available. [ABSTRACT FROM AUTHOR]