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The provision of critical ecosystem services like carbon sequestration by peatlands has been degraded around the globe. Peatland restoration represents an opportunity to tackle the twin global emergencies of climate breakdown and biodiversity decline. Nonetheless, restoration success relies on a sound understanding of recovery trajectories associated with different restoration techniques. Focusing on temperate/boreal Sphagnum‐dominated peatlands, we used a quantitative meta‐analysis of 28 studies representing 275 sites in 11 countries to test for effects of peatland status (intact, restored, and degraded), varying restoration interventions and time since restoration on vegetation as a key indicator of peatland condition and functioning. Enhanced restoration (such as active revegetation) resulted in recovery to predisturbance levels within 30–35 years for Sphagnum mosses, and 20–25 years for many other peatland specialist species, and was the only restoration approach where positive outcomes were seen across all vegetation response variables. The use of standard restoration techniques, such as rewetting, was projected to result in cover of Sphagnum mosses and peatland specialist plants reaching that of intact sites within 45–55 years post‐restoration. Passive restoration (cessation of the degrading activity with no active restoration) generally elicited limited recovery of keystone peatland vegetation (Sphagnum spp.) even after multiple decades. A lack of standardization in monitoring severely constrains the analysis of peatland restoration outcomes. Increased funding for monitoring and reporting outcomes, and improved monitoring consistency, could greatly enhance our understanding of peatland restoration ecology and improve practice. [ABSTRACT FROM AUTHOR]

During more than five centuries of human colonization, 50% of original peatlands in Azores have been destroyed or degraded, mainly due to pasture use, resulting in landscape changes and a loss of ecosystem biodiversity and services. This study aims to identify the most effective measures in the recovery and to detect initial responses (2 years). These are the first restoration experiments, carried out in a background of complete absence of strategies adapted for Azores pastured peatlands. In a post‐pastured peatland, 24 experiments were implemented, repeated in more degraded (northern) and more natural (southern) areas. The experiments were combinations of restoration measures, with the introduction of Juniperus brevifolia, Calluna vulgaris, and Sphagnum palustre and the use of management techniques to control herbaceous cover (alien‐rich herbaceous cover competing with Sphagnum or peatland natural shrubs): intensive and extensive grazing and grass cutting. Principal response curves and redundancy analyses were used to assess changes in the flora and the physicochemical parameters. Globally there was an increase in Sphagnum cover and a decrease in herbaceous species. This was accompanied by an increase in organic matter and a decrease in nitrogen. In more natural parcels (large artificially divided areas where different experiments were implemented), the most positive tendencies were associated with the combination of J. brevifolia planting and grass cutting. In more degraded areas, treatments had a lower impact, as the results tended to be similar to the control, pointing to an important natural regenerative succession dynamic that overlapped the response to the implemented treatments. [ABSTRACT FROM AUTHOR]

A low rate of establishment in brown mosses is generally observed following large-scale restoration of fens. As brown mosses are important components in peat accumulation in fens, their low recovery rate has been a concern in the past decade. It was suggested that the restoration method used for bogs, the Moss Layer Transfer Technique (MLTT) should be adapted for fen restoration by identifying factors limiting the establishment and recovery of brown mosses. In this study, we evaluated the regeneration potential of four common brown mosses, Aulacomnium palustre, Campylium stellatum, Scorpidium cossonii and Tomentypnum nitens, according to three factors that can have an impact during restoration: 1) distance of the fragment below the moss apex, 2) mechanical fragmentation of mosses, and 3) enhanced nutrient availability, and this, in growth chambers (within Petri dishes) and field experiments. Under controlled conditions, similar results were obtained for all four brown mosses studied: the severe fragmentation of mosses most drastically improved their regeneration potential. Phosphate fertilization, even at the lowest dose, increased moss regeneration, and brown mosses showed higher recovery in the first 3 cm below the apex. Liming only improved the regeneration of C. stellatum. However, unclear, and even contradicting results were obtained when treatments were applied in the field, where an overall very low establishment of brown mosses was observed in response to the rather prevailing adverse environmental conditions (e.g., erosion, frost heaving, low water table level). The direct application of some of our results into an adapted version of MLTT might be challenging, as it may require a certain level of meticulosity that large-scale mechanical fen restoration cannot provide. [ABSTRACT FROM AUTHOR]

Restoration of degraded peatland ecosystems (by rewetting) is undertaken to bring back key ecosystem services. However, the restoration process can have a range of ecohydrological effects, due to the associated physical and biogeochemical disturbance. In the case of northern peatlands drained by large and deep ditches, the rewetting effects are relatively unknown. The raised bog Grande plée Bleue (1,500 ha) is one of the largest pristine bogs in the St‐Lawrence lowlands in North America; however, it contained an old (>60 years), 750 m long, 3.5 m deep, and 8 m wide ditch. Rewetting of the area affected by the ditch was carried out by the construction of six dams at 40 cm elevation intervals and felling of all trees (with diameter at breast height >10 cm) within 30 m. Water table was restored to levels similar to intact bog reference sites, only at elevation differences up to 17 cm from the nearest lower dam, while rewetting did not affect pore‐water chemistry. Five to 6 years post‐rewetting, the cover of both pioneer mosses, and late successional mosses (Sphagnum) had not changed significantly compared with pre‐rewetting. This may have been due to the presence of dense shrub cover. For more effective ecohydrological restoration, dams should be spaced at smaller elevation intervals (e.g., every 20 cm of elevation or less), to allow recovery of water table along the entire length of the ditch, and vegetation introduction using the moss layer transfer technique may accelerate Sphagnum recruitment, especially in the few first metres from the ditch. [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]

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]

Our study found that a water level close to the surface and a seedbed composed of bare peat or a Sphagnum carpet favored the germination of vascular species associated with pools in peatlands. A greenhouse experiment was conducted to study the impact of seedbed and water level on the germination and growth of 7 plant species associated with pools: Carex limosa L, C magellanica Lam. ssp. irrigua (Wahlenb.) Hultén, C. oligosperma Michx., C pauciflora Lightf., and Rhynchospora alba (L.) Vahl from the Cyperaceae family as well as Drosera intermedia Hayne (Droseraceae) and Scheuchzeria palustris L. (Scheuchzeriaceae). The 3 seedbeds tested were 1) bare peat; 2) a carpet of Sphagnum cuspidatum Ehrh. ex Hoffm. and 5. faiiax (Klinggr.) Klinggr. (Sphagnaceae); and 3) a carpet of Cladopodieila fiuitans (Nees) H. Buch (Cephalaziaceae), common bryophytes along pool edges. Seedbeds were combined with 2 water levels (0 and 10 cm below the soil surface) in a complete factorial block design. Germination periods were generally longer when seeds were submitted to drier conditions and placed on C. fiuitans carpets. Conditions favoring biomass production were more variable among species. These results will facilitate the identification of the best ecological conditions for successful establishment of pool edge species in the context of restoration projects, thereby increasing biodiversity and ecological value of restored peatlands. [ABSTRACT FROM AUTHOR]

Since the early 1990s, restoration techniques have been developed for milled and cutover peatlands in eastern Canada. These techniques are based on the active reintroduction of peatland plant diaspores, blocking drain- age, and the use of straw mulch to improve surface conditions. This study examines the effectiveness of using shallow (20 cm deep) basins of various widths to improve the success of current peatland restoration techniques. It comprises three different experiments, each spanning three or four growing seasons and combining both small-scale manual and large-scale mechanized plant reintroductions. Cover data recorded in two of the experiments were regressed against a series of environmental factors to determine how Sphagnum establishment success was related to abiotic variables such as moisture, water ponding, surface roughness, and mulch cover. Results of these experiments demonstrate that shallow basins were generally effective at promoting Sphagnum establishment and that this effect extends beyond the positive impact that basins have on hydrological conditions. Basins of various widths were equally successful. Soil-moisture content (linear positive effect) and duration and severity of flooding events (quadratic effect) were shown to be determinant of plant recovery. Other factors such as the density of straw cover (positive effect) and surface roughness (negative effect) were also instrumental in explaining local variation in Sphagnum cover. Plant cover after three and four growing seasons averaged 20-25% in mechanical reintroductions and 40-60% in manual reintroductions, demonstrating the overall effectiveness of the restoration techniques used. [ABSTRACT FROM AUTHOR]

A partially peat-extracted coastal bog contaminated by seawater was barren and required revegetation as a wetland. Peat fields were rectangular in shape, cambered in cross-section profile, and separated by drainage ditches. Common to all peat fields were symmetrical patterns in micro-topography with slopes between differences in elevation. Saline non-waterlogged slopes of ∼5% occurred as a symmetrical pair on each side of the crest of the cambered profile, at one end of each peat field. Three rows were laid across this slope (Top, Middle, and Bottom rows) and transplanted with naturally-growing plant species with their sand substrate, in three experiments, and grown for a year. In the Spartina pectinata experiment, bare root stem sections were also planted. Another experiment was conducted to determine changes in the characteristics of a volume of sand when incubated in saline peat fields. We found the salinity of peat increased with moisture downslope, and pH decreased with increase in salinity. S. pectinata grew best when planted with its sand substrate compared with bare root stem section, and when planted in Bottom rows. Juncus balticus had excellent growth in all rows. Unexpectedly, Festuca rubra that was inconspicuous beneath the J. balticus canopy in the natural donor site grew densely within the J. balticus sods. Agrostis stolonifera grew well but seemed to show intolerance to the surrounding acidic peat by curling up its stolons. The pH of the incubated sand volume was much higher than the surrounding peat. These studies suggest that recognition of plant niches and pH manipulation are important in the revegetation of disturbed Sphagnum peatlands that are found abundantly in the northern hemisphere. Results are also relevant to the reclamation of other disturbed lands. [ABSTRACT FROM AUTHOR]