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The moss layer transfer technique has been developed to restore the carbon sequestration function and typical vegetation of Sphagnum-dominated peatlands after peat extraction in North America. However, the technique does not lead to successful bryophyte establishment when applied to peatlands with a richer residual fen peat. Therefore, we evaluated an alternative method of active rewetting and passive vegetation establishment using vegetation surveys and carbon dioxide and methane (CH4) flux measurements at a post-extracted fen in southern Manitoba, Canada. After one growing season post-rewetting, wetland vegetation established and the site was a net carbon sink over the growing season. However, high abundance of Carex lasiocarpa 10 years post-treatment led to higher CH4 emissions than the reference ecosystem. Successful establishment of wetland vegetation is attributed to the area being surrounded by undisturbed fens that can provide a local source of plant propagules. Bryophyte expansion was less successful than vascular plants, likely due to episodic flooding and shading from the sedge communities. Therefore, careful management of water levels to just below the peat surface is needed if reference vegetation community recovery is the goal of restoration. Water level management will also play a key role in controlling CH4 emissions to maximize carbon sequestration potential. [ABSTRACT FROM AUTHOR]

Litter decomposition is a key process controlling carbon (C) sequestration in Sphagnum dominated peatlands. Peatland drainage lowers the water table, increases vascular plant richness, and alters species evenness. We hypothesized that abiotic and biotic changes following peatland drainage would greatly accelerate litter decomposition. This hypothesis was tested by a litter decomposition experiment in an undrained and a drained area of a peatland which was partially drained 30 years ago. Litter bags filled with shoots of the peat moss Sphagnum magellanicum and leaves of the dwarf shrub Potentilla fruticosa as single species and species mixtures with three evenness treatments were placed at the surface of the peatland. After 6 months (from August onwards) of decomposition, the single species litter of Potentilla fruticosa, with low initial C/N ratio, decomposed much faster than S. magellanicum litter, with high initial C/N ratio in both undrained and drained areas. Overall, mixed litter produced antagonistic effects (observed values less than expected) on decomposition and C/N ratio. Litter mixtures dominated by S. magellanicum showed lower mass loss than other mixtures. Contrary to our expectation, the undrained area showed higher decomposition than the drained area. Our study suggests that drainage-induced alteration in plant diversity slows down litter decomposition in a short term. However, in drained peatlands, lower C/N ratio of mixed litter may enhance decomposition and reduce C sequestration over time. [ABSTRACT FROM AUTHOR]

In a controlled field experiment, we tested the effect of plant biodiversity on carbon accumulation in a formerly-extracted peatland that was rewetted and re-vegetated. We monitored carbon fluxes in experimental units re-vegetated with different numbers and types of characteristic minerotrophic peatland species, planted in monoculture and mixed treatments. Using measured environmental variables, we modelled the different components of carbon flux (photosynthesis, respiration and methane flux) and simulated the Net Seasonal Carbon Flux for three standard wetness scenarios of each planting treatment. We tested the effect of species and functional group richness, species and functional group identity and species interactions on Net Seasonal Carbon Flux. Our findings did not indicate any significant effect of the richness of species or plant functional groups on carbon accumulation. However, the presence of key species was important; Carex aquatilis, particularly when planted alone, significantly increased carbon accumulation; other graminoid species were not associated with the same effect. Mixed-species treatments did not accumulate more carbon than was expected of the same species when planted in monoculture, providing no evidence for an overall species interaction effect. Our results suggest that in the context of restored minerotrophic peatlands, species identity is more important than species/functional group richness or species-interaction for driving carbon accumulation. [ABSTRACT FROM AUTHOR]

The study central goal was to analyze secondary succession in a degraded peatland: (1) Sphagnum distribution trends and (2) successional patterns. Main study sites were adjacent abandoned pastures, where grazing was carried out in former peatland and where degradation had occurred, hereafter referred as degraded peatland. (1) Degraded peatland was mapped in 2006 (while it was still a pasture, grazed for over 30 years), and throughout the study period in 2013 (2 years post-abandonment) and 2015 (4 years post-abandonment). The baseline assessment of 2006 revealed that Sphagnum spp. were present in 7% of the area, which pointed at the resilience of the peat ecosystem. After the grazing ceased, Sphagnum cover increased to 17% and 39%, in the next 2 and 4 years respectively post animal removal. (2) To gain a general comprehension of flora and vegetation changes along the regenerative sucession, 48 permanent plots were established in the degraded peatland. In two other study sites, a further twenty plots were established, ten plots in a semi-natural peatland area where grazing ceased 30 years ago and ten others in a natural peatland. These were monitored between July 2012 and July 2015 (triannual). After 4 years, the formerly degraded peatland showed considerable recovery with a growth of Sphagnum spp. cover as well as other species like Calluna vulgaris, tending to become more similar to semi-natural and natural peatlands. Grazing cessation induced the regenerative succession that could lead to self-recovery, which, in optimal conditions, could be an alternative to active restoration in Azores. [ABSTRACT FROM AUTHOR]

Aims: Separating the effect of resource competition from allelopathy in plants is challenging and it has never been attempted in closely related co-occurring bryophytes. In peatlands, peat mosses (Sphagnum spp.) show niche differentiation along water table level (WTL) gradient. Our aim was to evaluate whether the hummock species, S. magellanicum would be a winner at low WTL due to its allelopathic advantage and the hollow species, S. angustifolium would win by virtue of its superior competitive ability but not of allelopathy at high WTL due to dilution of its allelochemicals. Methods: We used a nested, field experimental design, with two WTL treatments—low WTL (hummock habitat) and high WTL (hollow habitat)—and three different inter-specific interactions: 1) monoculture; 2) mixed culture without activated charcoal; and 3) mixed culture with activated charcoal added to the neighbor. We measured growth and biochemical traits of the two species and compared the index of relative neighbor effect on each other. Results: We discovered a trade-off between biomass production (competitive outcome) and phenolic content (allelopathy) in these species. At low WTL, allelopathy of the hummock species is the main mechanism to suppress the hollow species, whereas at high WTL, competition is the main driver to suppress the hummock species. Conclusions: Competitive advantage in Sphagnum is mediated by both resource competition and allelopathy of the co-occurring species through niche differentiation along a WTL gradient. Unlike vascular plants, Sphagnum mosses can serve as excellent model organisms in studying allelopathic interaction since they bypass the complexity of plant-soil interactions. [ABSTRACT FROM AUTHOR]

Peatlands are abundant in the boreal region of Canada but little is known about their restoration on oil sands well pads. The goal of this study is to compare the reintroduction of different peatland plant communities and substrate amendments/decompaction in order to rehabilitate peatland vegetation on former in situ well pads constructed in wetlands. One field experiment tested which peatland plant communities (Shrubby Rich Fen, Treed Rich Fen) would best colonize different substrates (sawdust, clay loam, mix sawdust-clay, peat, surface roughness). We found that the moss layer transfer technique (MLTT) facilitated the establishment of peatland communities on residual mineral soil used to construct the pad, when shaved back to an average water level of the surrounding wetland. The choice of peatland plant community is key to the introduction of bryophytes. Peat amendment facilitated the establishment of plants, whereas soil decompaction had no effect. The MLTT is a promising approach to restore fen plants on well pads. We recommend a scale-up experiment for a whole well site to test the validity of MLTT along different pad removal techniques. [ABSTRACT FROM AUTHOR]

Several studies contributed to the development of restoration techniques for open Sphagnum-dominated habitats on peat-extracted bogs. Yet, in exception to some afforestation efforts, connectivity between restored sites and surrounding landscapes has received little attention. The general goal of this study is to ameliorate management of very shallow peat fields (<30 cm) located within the margins of peat-extracted bogs. Firstly, to assist decision making in peatland management, baseline ecological conditions, peat physicochemistry and spontaneous vegetation recolonization were assessed for 18 of these fields. This first study revealed that (1) concentrations of several macro-nutrients are almost one order of magnitude lower for unrestored fields than previously characterized natural lagg habitats of the same region, and (2) there is little spontaneous colonization. In a second study, peat chemistry and soil/air microclimate were evaluated in plantations established on shallow residual peat (a 21-year-old Larix laricina plantation and an 18-year-old Picea mariana plantation) and compared to adjacent unrestored shallow bare-peat fields. This second study showed that afforested peat fields are characterized by (1) a soil enriched in nutrients, notably in N, P, and K, and (2) a more humid and cooler microclimate at the soil/air interface, with less daily humidity and temperature fluctuations. These results indicate that afforestation is an appropriate approach to start an ecological recovery. Yet, the absence of natural recolonization by herbs and mosses in the understory of afforested peat fields suggests that reintroduction of appropriate understory species should also be considered if the goal is to restore a fully functional ecosystem. [ABSTRACT FROM AUTHOR]

Background and Aims: Peatland methane (CH) fluxes may vary between plant types; however, in mixed communities, the specific role of each species is difficult to distinguish. The goal of this study was to determine the individual and interacting effect of moss, graminoid and shrub plant functional types on CH dynamics of experimentally planted plots in a rewetted minerotrophic peatland. Methods: We measured CH flux, pore water CH concentration and CH production and oxidation potential in pure stands of reintroduced Tomenthypnum nitens (Hedw.) Loeske, Carex aquatilis Wahlenb, or Myrica gale L., as well as mixtures of T. nitens + C. aquatilis and T. nitens + M. gale. Methane flux was also measured on bare peat plots. Results: The presence of both the graminoid C. aquatilis and the shrub M. gale resulted in the highest CH production potential in near surface peat (10 cm). The presence of moss ( T. nitens) and C. aquatilis significantly increased CH oxidation potential. Water table position was a significant control on CH flux, but the presence of C. aquatilis maintained higher flux even at dry plots. Plots including C. aquatilis had significantly lower pore water CH concentration at 30 cm depth, likely reflecting CH oxidation and transport. Conclusions: Management of restored sites aiming to reduce CH flux should focus on hydrology, i.e. water table position. The presence of graminoids enhances CH flux, while moss presence may result in lower CH emission. [ABSTRACT FROM AUTHOR]

Ecological gradients have always been a central theme of plant ecology. Yet, very little is known on the bog-lagg-mineral land gradient. Improved knowledge of this gradient is important to the understanding of wetland plant ecology and wetland delineation alike. In this study, the relation between vegetation composition and peat thickness is analysed in 20 raised bogs of eastern Canada using split moving window dissimilarity analysis. Four different transition types are identified: (1) an abrupt transition without an ecotonal community; (2) a narrow transition with a lagg-swamp ecotonal community (most common transition type); (3) a narrow transition with two ecotonal communities (a lagg-fen and a lagg-swamp); and (4) a broad transition with a large wetland adjacent to the bog. Laggs that could be defined as separate habitat (type 1) occured, on average, on peat soil over 30 cm thick (defined as > 30 % dry mass of organic matter), making the lagg an integral part of the peatland complex. Other unique features of the lagg are: (1) a very densely structured habitat where trees, shrubs, herbs and Sphagnum mosses are abundant; (2) soils characterised by relatively high contents of total nitrogen and total phosphorus, but a particularly low N:P ratio (8.7 ± 2.5); and (3) a relatively high water table, which fluctuates substantially (from −33 to +10 cm in site A; from −12 to +10 in site B). [ABSTRACT FROM AUTHOR]

The organic matter accumulation potential of a restored bog was estimated over 2 years as a balance between losses to decomposition and inputs through above-ground net primary productivity (AGNPP) in five micro-habitats of increasing complexity (relating to the moss carpet thickness and the number of vegetation functional groups). Decomposition and accumulation rates variations were hypothesized to lead to higher organic matter accumulation potential in the more complex micro-habitats. In general, for a given litter type, the mass losses and decomposition rates were rather homogeneous between micro-habitats, but, they were correlated to the cover of particular species: Eriophorum vaginatum with slower decomposition rates, and Ledum groendlandicum or Kalmia angustifolia with higher rates. Therefore, the abundance of some peatland species, rather than the habitat complexity itself, was a driver of decomposition rates. While the Sphagnum AGNPP did not compensate for decomposition losses, the organic matter accumulation potential was tipped towards a sink (positive) by the contribution of vascular species to the AGNPP. The organic matter accumulation potentials are much improved by the presence of Sphagnum, but from a restoration perspective, promoting the growth of vascular peatland species might also be a key to achieving a positive balance of organic matter accumulation. [ABSTRACT FROM AUTHOR]

Monitoring is an essential step to assess vegetation trajectories post-restoration and ultimately evaluate success. In this paper, we compare two monitoring methods, the line-point intercept (LPI) and the permanent plot (PP) methods, for evaluating plant recovery of a restored cut-over peatland (8.5 ha), following a 'moss layer transfer technique'. We used the LPI method to estimate covers (from frequency measures) for each plant species using a systematic grid of approximately 5,700 points (every 3 m × 5 m). In parallel, 43 PP (3 m × 8 m) were established and used to evaluate plant covers. The post-restoration recovery of vegetation was assessed against a reference ecosystem encompassing the variation in species cover from natural undisturbed peatlands in the same region. For all plant groups considered, the LPI consistently showed higher cover estimates than the PP method. Discrepancy between the two methods was particularly evident for the Ericaceae group. A complementary sampling method, the line-intercept (LI), showed strong correlations with the visual estimations of Ericaceae covers (akin to PP), suggesting an overestimation from the LPI method. Most life form groups of the restored peatlands are developing a structure similar to the regional reference ecosystem 8 years post-restoration with the herb group being still most dissimilar. Indeed, when analyzing the temporal evolution of the different key peatland plant components, several are within the range of regional abundance values or moving positively towards range of cover abundance of the reference system such as Sphagnum cover, a key peat-accumulating plant group. [ABSTRACT FROM AUTHOR]

Following ecosystem-scale restoration of a post-harvested bog in Eastern Canada, a long term monitoring program was set up. Peat, water and plant chemistry data were collected during 7 years in a restored peatland, an adjoining post-harvested non-restored peatland, and in a neighboring natural peatland to determine the potential of chemistry data for evaluating of restoration success over time. We used a multivariate Principal Response Curves (PRC) approach to study the temporal evolution of peat, water, and plant tissue chemistry. Nitrogen, iron, and sodium were the most responsive elements to restoration in the peat. Water chemistry was still different between natural and restored sections 7 years after restoration, but the difference was not constant over the growing season. The analyses of plant tissue chemistry provided useful information related to fundamental processes (nutrient retention/leaching, plant nutrition). Among other, it highlighted P deficiencies in the non-restored section, and nutrient replenishment in the restored plant tissues. P levels appear to be a good indicator of restoration success and should be used routinely in monitoring studies. Since the three plants species tested in this study displayed different responses to restoration, we also recommend targeting key species or functional groups for monitoring. [ABSTRACT FROM AUTHOR]

Herbivores can shape plant communities, especially in the Arctic. We tested the role of geese for structuring bryophyte communities at fine spatial scales in the arctic tundra by excluding them from 4 × 4 m areas. We surveyed the presence and absence of bryophyte species in quadrats (10 × 10 cm) divided into 25 cells outside and inside these exclosures, after 5 and 11 years of treatment. Species richness per cell (4 cm2) was higher in the presence of geese, especially after 11 years of treatment, while geese had little effect on richness at larger scales (i.e. quadrat and whole exclosure). The slope of the species–area relationship within quadrats was consequently shallower outside exclosures. Our results further suggest that the community outside the exclosures was more variable in space and time than that inside the exclosures. We conclude that goose foraging activity promotes the coexistence of bryophyte species at the centimetre scale. [ABSTRACT FROM AUTHOR]

Modern extraction methods permit peat to be extracted to the minerotrophic layer of ombrotrophic peatlands (bogs). As the environmental conditions of these harvested peatlands are similar to minerotrophic peatlands (fens), such sites should be restored towards a fen system. However, it is not known whether fen species would recolonize such harvested sites on their own. We surveyed vegetation and environmental variables in 28 harvested peatlands with minerotrophic residual peat across Canada and in Minnesota, USA, and compared them to 11 undisturbed fens. Compared to harvested bogs previously studied, the harvested fens sampled in this study revegetated remarkably quickly (50% 70% vegetation cover) when the hydrological conditions were suitable. However, revegetation was less extensive for sites that were still drained (25% vegetation cover). A high water table and a thin layer of residual peat were the most important factors contributing to rapid recolonization rates. Although the harvested fens were rapidly recolonized, species composition was not the same as observed on undisturbed fens. Carex and Sphagnum, dominant in undisturbed fens, generally did not recolonize harvested fens. Thus, whether the goal is to increase species richness or to ensure the return of peat accumulating functions, fen species may have to be actively introduced. [ABSTRACT FROM AUTHOR]

Two controlled experiments were conducted to evaluate the potential for vascular plants to germinate and establish in milled peatlands and to assess whether easily measured plant traits can be used to predict their probable success. Study species included twenty species of perennial herbs, shrubs and trees occurring frequently in undisturbed bogs or abandoned milled bogs in Québec, Canada. First, a glasshouse experiment was performed to test the effect of burial under peat on germination and seedling emergence. Second, a growth chamber experiment was conducted to measure relative growth rate and other growth parameters of seedlings between 1 and 3 weeks of age. In the burial experiment, seedling emergence decreased exponentially with peat depth for most species examined. The slope of the exponential decline varied between species and was strongly correlated to seed mass. Seeds less than 0.1 mg in mass were most sensitive to burial. In the seedling growth experiments, Betula species had the highest absolute and relative growth rates, which may help to explain their prevalence in milled bogs. Relative growth rate (RGR) was not correlated with seed mass, however it was strongly correlated with leaf area ratio (LAR) and especially specific leaf area (SLA) of seedlings, except for species with seed mass less than 0.01 mg. Screening of species for seed mass and SLA should help predict their germination and establishment success or failure in milled peatlands and allow more directed interventions to favour the establishment of desirable species in milled bogs. [ABSTRACT FROM AUTHOR]

Sphagnum dominated peatlands do not rehabilitate well after being cutover (mined) for peat and some action needs to be taken in order to restore these sites within a human generation. Peatland restoration is recent and has seen significant advances in the 1990s. A new approach addressing the North American context has been developed and is presented in this paper. The short-term goal of this approach is to establish a plant cover composed of peat bog species and to restore a water regime characteristic of peatland ecosystems. The long-term objective is to return the cutover areas to functional peat accumulating ecosystems. The approach developed for peatland restoration in North America involves the following steps: 1) field preparation, 2) diaspore collection, 3) diaspore introduction, 4) diaspore protection, and 5) fertilization. Field preparation aims at providing suitable hydrological conditions for diaspores through creation of microtopography and water retention basins, re-shaping cutover fields and blocking ditches. It is site specific because it depends largely on local conditions. The second step is the collection of the top 10 centimetres of the living vegetation in a natural bog as a source of diaspores. It is recommended to use a ratio of surface collected to surface restored between 1: 10 and 1: 15 in order to minimize the impact on natural bogs and to insure rapid plant establishment in less than four years. Diaspores are then spread as a thin layer on the bare peat surfaces to be restored. It has been demonstrated that too scant or too thick a layer decreases plant establishment success. Diaspores are then covered by a straw mulch applied at a rate of 3 000 kg ha-1 which provides improved water availability and temperature conditions. Finally, phosphorus fertilization favours more rapid substrate colonization by vascular plants, which have been shown to help stabilize the bare peat surface and act as nurse plants to the Sphagnum mosses. [ABSTRACT FROM AUTHOR]

Recent literature on peatland restoration indicates as a general goal repairing or rebuilding ecosystems by restoring ecosystem structure, trophic organization, biodiversity, and functions to those characteristic of the type of peatland to which the damaged ecosystem belonged, or at least to an earlier successional stage. Attainment requires provision of an appropriate hydrological regime, manipulating surface topography, improving microclimate, adding appropriate diaspores, manipulating base status where necessary, fertilizing in some cases, excluding inappropriate invaders, adaptively managing through at least one flood/drought cycle to ensure sustainability, and monitoring on a scale of decades. Several matching conditions favoring or opposing restoration are suggested. In the restoration of peatlands, successes have generally been those of short-term repair. Periods of restoration have been much too short to ensure progression to, or even well toward, a fully functional peatland reasonably compatible with the pristine state of similar peatlands elsewhere, although with altered surface patterns. Long-term monitoring of peatland-restoration projects is essential for a better understanding of how to carry out such restoration successfully. Paleoecology is suggested as an underutilized tool in peatland restoration. [ABSTRACT FROM AUTHOR]

In the original publication, the Table 1 was published incorrectly. The correct version of Table 1 is given in this correction. The original article has been corrected. [ABSTRACT FROM AUTHOR]

The article cites a research study on the restoration of sphagnum dominated peatlands. This study has emerged as a new scientific field in the last fifteen years. The need to restore peatlands was partly induced by the wider recognition of wetland values in the landscape and the recent extensive commercial uses of peatlands for horticultural products, cranberry production, energy fuels, etc. In the last few years, several studies focused on identifying the barriers to rapid primary/secondary succession of sphagnum species and trying to restore or measure the return of different ecosystem functions of a peatland.

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]