Allometric equations for estimating aboveground biomass (AGB) from easily measured plant attributes are unavailable for most species common to mid-continental boreal peatlands, where shrubs comprise a large component of the vegetation community. Our study develops allometric equations for three dominant genera found in boreal fens: Alnus spp. (alder), Salix spp. (willow) and Betula pumila (bog birch). Two different types of local equations were developed: (1) individual equations based on genus/phylogeny, and (2) a general equation that pooled all individuals regardless of genera. The general equation had a R2 = 0.97 (n = 82), and was not significantly different (p > 0.05) than any of the phylogenetic equations. This indicated that a single generalized equation is sufficient in estimating AGB for all three genera occurring in our study area. A closer look at the performance of the general equation revealed that smaller stems were predicted less accurately than larger stems because of the higher variability of leafy biomass found in small individuals. Previously published equations developed in other ecoregions did not perform as well as our local equations.
Northern peatlands store globally significant amounts of soil carbon that could be released to the atmosphere under drier conditions induced by climate change. We measured forest floor respiration (RFF) at hummocks and hollows in a treed boreal bog in Alberta, Canada and partitioned the flux into aboveground forest floor autotrophic, belowground forest floor autotrophic, belowground tree respiration, and heterotrophic respiration using a series of clipping and trenching experiments. These fluxes were compared to those measured at sites within the same bog where water‐table (WT) was drawn down for 2 and 12 years. Experimental WT drawdown significantly increased RFF with greater increases at hummocks than hollows. Greater RFF was largely driven by increased autotrophic respiration driven by increased growth of trees and shrubs in response to drier conditions; heterotrophic respiration accounted for a declining proportion of RFF with time since drainage. Heterotrophic respiration was increased at hollows, suggesting that soil carbon may be lost from these sites in response to climate change induced drying. Overall, although WT drawdown increased RFF, the substantial contribution of autotrophic respiration to RFF suggests that peat carbon stocks are unlikely to be rapidly destabilized by drying conditions.
In this study, our goal was to adapt the moss layer transfer technique (MLTT), first developed to restore degraded Sphagnum‐dominated peatland explicitly with a bryophyte layer, to a former in‐situ oil sands well‐pad constructed with nearby mineral fill in northwestern Alberta, Canada. Mineral fill was either completely removed or partially removed with residual fill buried under excavated and decompacted peat, followed by the transfer of donor moss collected from nearby linear features with different plant communities in peatlands. Three years after MLTT, peatland vegetation covers 63% of the site. Carex spp. dominate with 36% coverage, followed by mosses at 12%, including 3% Sphagnum spp. and 8% fen mosses, and shrubs at 8%. Different substrate adjustment treatments and types of donor moss had negligible impact on vegetation development although areas without MLTT remained devoid of mosses and had the lowest peatland species cover. Instead, surface elevation, moisture conditions, and substrate chemistry played important roles in shaping the vegetation communities. The prompt introduction and establishment of peatland donor species through MLTT was crucial to the overall re‐establishment of peatland vegetation. This is the first full pad scale study to prove that a flat, moist peat surface created by the removal and/or burial of mineral fill can support peatland vegetation development, particularly ground layer bryophytes. Overall, the reclaimed well‐pad appears to be on trajectory toward becoming a functional peatland and our approaches should be considered and tested in future well‐pad reclamation trials.
Many peatlands on the North American Western Boreal Plain have been disturbed by industry, including through the construction of thousands of oil well pads. The introduction of fen mosses onto residual mineral well pads following their partial removal has been proposed as a novel technique to restore these sites. However, it has remained unclear whether this would support the requisite hydrological conditions for fen moss establishment. To assess this, a field study of hydrological function at a partially removed pad undergoing restoration near Slave Lake, Alberta, Canada was undertaken. Specifically, the hydrophysical properties of the residual fill and adjacent peatland (including hydraulic conductivity, bulk density, and porosity) were characterized, and related to subsurface flow and water table regulation within the partially removed pad and adjacent peatland. The results demonstrate that flow through the peatland was disrupted by the low saturated hydraulic conductivity of the residual fill (1.15 × 10-5 m s-1) and the compacted underlying peat (4.91 × 10-6 m s-1), resulting in preferential flow around the pad. On the residual pad, hydrological connectivity with the adjacent peatland resulted in a well-regulated, near-surface water table across nearly half of its surface area. However, limitations on subsurface flow through the pad footprint resulted in variable hydrological dynamics across much of its interior. These findings suggest that partially removed well pads have the potential to support requisite hydrological conditions for fen moss establishment, but further development of the technique should be undertaken to improve subsurface hydrological connectivity with adjacent peatlands.