Personne : Rochefort, Line
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Université Laval. Département de phytologie
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- PublicationAccès libreReintroduction of salt marsh vegetation and phosphorus fertilisation improve plant colonisation on seawater-contaminated cutover bogs(International Mire Conservation Group, 2016-01-01) Hogue-Hugron, Sandrine; Emond, Catherine; Rochefort, Line; Lapointe, LineCoastal bogs that are used for peat extraction are prone to contamination by seawater during storm events. Once contaminated, they remain mostly bare because of the combination of high salinity, low pH, high water table and low nutrient availability. The goal of this research was to investigate how plant colonisation at salt-contaminated bogs can be accelerated, in order to prevent erosion and fluvial export of the peat. At two seawater-contaminated bogs, we tested the application of rock phosphate and dolomitic lime in combination with five plant introduction treatments&58; transplantation of Carex paleacea&59; transplantation of Spartina pectinata&59; transfer of salt marsh diaspores in July&59; transfer of salt marsh diaspores in August&59; and no treatment (control). The effects of different doses of lime on the growth of C. paleacea and S. pectinata were also investigated in a greenhouse experiment. In the field, phosphorus fertilisation improved plant growth. Transplantation of C. paleacea resulted in the highest plant colonisation, whereas salt marsh diaspore transfer led to the highest species diversity. Lime applications did not improve plant establishment in either the field or the greenhouse. To promote revegetation of seawater-contaminated cutover bogs, adding P is an asset, Carex paleacea is a good species to transplant, and the transfer of salt marsh diaspores improves plant diversity.
- PublicationAccès libreCombining indicator species and key environmental and management factors to predict restoration success of degraded ecosystems(Elsevier Science Ireland, 2014-11-01) Rochefort, Line; Poulin, Monique; González, Eduardo; Boudreau, StéphanieWhen evaluating the success or failure of ecological restoration projects, practitioners need to verify success within the first few years of the monitoring process to apply corrective measures if necessary or to reclaim environmental down payment where required. This could be achieved with ecological indicators, if they can be easily and routinely measured and are representative of the complexity of the restored ecosystems. We used peatlands restored after horticultural peat extraction in eastern Canada to test a methodological approach that predicts restoration success early after restoration implementation. The goal of restoration of these extracted peatlands is to re-establish a moss carpet typically dominated by Sphagnum mosses, the main peat-accumulating plant group in these northern ecosystems. Vegetation in a total of 152 plots in 41 peatlands restored after peat extraction activities and distributed across a span of 600 km was monitored every 2 years since the third year after restoration. The plots were clustered in three restoration outcome categories: Sphagnum-dominated, bare peat-dominated and Polytrichum-dominated, according to their characteristic vegetation composition at the time of the latest survey for each plot (4–11 years since restoration). Second, vegetation composition in the same plots from the earliest survey, 3 years since restoration, and key environmental and management variables such as summer temperature, effectiveness of ditch blockage, season of restoration works and delay in P fertilization were analyzed using linear discriminant analysis (LDA) to obtain the combination of parameters that best discriminated between the restoration outcome categories. LDA correctly classified 71% of the plots of a calibration database (for which 75% of the sectors were used) and 75% of a validation database (for which 25% of the sectors were used) into the three categories. The obtained LDA models can be used to allocate new plots to one of the restoration outcome categories by providing a series of linear equations (classification functions) that are computed from the combination of ecological indicators. One additional and recently restored peatland was used to illustrate application of these equations of the LDA model to predict future restoration outcome and subsequently adapt management strategies. Such a LDA model provides an unequivocal (i.e., one new plot assigned to one and only one restoration outcome category) prediction of success based on multiple but simple, easily recognizable indicators and spares managers the complex task of interpreting many individual predictors for establishing a clear diagnosis
- PublicationAccès libreCan indicator species predict restoration outcomes early in the monitoring process? A case study with peatlands(Elsevier Science Ireland, 2013-09-01) Hogue-Hugron, Sandrine; Rochefort, Line; Boudreau, Stéphane; Poulin, Monique; González, EduardoSuccess in ecological restoration is rarely assessed rigorously due to insufficient planning for post-restoration monitoring programs, limited funding and, especially, lack of scientifically validated evaluation criteria and protocols. In this article, we propose the use of the Indicator Value Index technique (IndVal), which statistically determines the association of species to one or several particular site types, to obtain indicators of success at the early stages of the recovery process in restoration projects. Peat bogs harvested by vacuum-milling, subsequently restored by a moss-transfer technique and regularly monitored for ~10 years were used as a model system to test this approach. We first identified 34 restored sectors of ~10 ha from 4 to 11 years old in twelve eastern-Canadian bogs. These sectors were then classified according to their degree of success in recovering a typical sphagnum moss carpet (restoration goal). Then, we retrospectively reviewed vegetation communities recorded at the third year after restoration to identify indicator species of different categories of restoration success, using the IndVal methodology. By identifying early indicator species, our method provides a tool that guides intervention soon after restoration if a site is not on a desired successional trajectory. Typical bog species, namely the bryophytes S. rubellum and Mylia anomala and the tree Picea mariana, were indicative of successful restoration; while bare peat, lichens and one species of ericaceous shrubs (Empetrum nigrum), which cope better under drier conditions, indicated sites where restoration failed. A surprising finding was that the moss Polytrichum strictum, which is known to facilitate the colonization of sphagnum in disturbed peatlands, is an early indicator of unsuccessful restoration. This finding made us question the nursing role of P. strictum at a cover threshold above ca. 30%, when P. strictum could be outcompeting sphagnum and become dominant. We conclude that the IndVal method is an effective tool to identify early indicators of restoration success when combined with a thoughtful examination of species frequency and cover within each site type.
- PublicationAccès libreIs rewetting enough to recover Sphagnum and associated peat-accumulating species in traditionally exploited bogs?(Kluwer Academic, 2014-02-01) Rochefort, Line; Henstra, S. W.; Poulin, Monique; González, Eduardo; Bradfield, GaryWhen restoring ecosystems, the simple removal of stresses causing degradation may seem preferable over other more costly and time consuming approaches. However, some restoration techniques can be implemented at reasonable cost and with increased efficiency in certain cases. We examined the successional trajectories of vegetation within abandoned block-cut peatlands in a major peat-producing region of Eastern Canada to evaluate whether the use of rewetting as a restoration technique can assist in the recovery of a typical bog plant community dominated by Sphagnum compared to spontaneous recolonization alone. We surveyed a total of 55 trenches in 6 peatlands twice, ~25 and ~35 years after the cessation of peat extraction. Canonical ordinations evidenced a generalized process of afforestation during the decade studied, partially driven by agricultural drainage in the surrounding landscape. Plant communities were dominated by ericaceous shrubs that hampered the spontaneous recovery of a Sphagnum-dominated system typical of bogs in the short and medium-term. Three of the six peatlands surveyed were partially restored by blocking drainage ditches. There, we surveyed plant composition in rewetted (28) and non-rewetted (26) trenches and observed that rewetting mitigated the increase in tree dominance, decreased the dominance by ericaceous shrubs, and favored the spread of non-vascular species with a wet habitat preference (notably Sphagnum species from the Cuspidata section). We conclude that the use of low intervention restoration techniques in block-cut bogs, such as the blockage of former drainage ditches, can re-orient undesired vegetation trajectories driven by spontaneous recolonization alone.
- PublicationAccès libreTrajectories of plant recovery in block-cut peatlands 35 years after peat extraction(Landsc. Archit. Decis. Support Syst. PhD Sch. Szent István Univ., 2013) Rochefort, Line; Poulin, Monique; González, EduardoThe initial question of any ecological restoration project should be whether the degraded ecosystem may recover spontaneously in a reasonable time period or active intervention is needed. We examined the successional trajectories of vegetation within peatlands exploited by the traditional blockcut technique in Eastern Canada, with the final purpose of identifying sites which need human intervention to ensure the return of a typical Sphagnum-dominated bog community that accumulates C. Ordinations showed that the development of vegetation was different between three block-cut peatland regions. Peatlands of one of the regions were initially colonized by tall, dense ericaceous shrubs. There, communities tended to become increasingly dominated by trees and understories were closing over time, therefore not being on a trajectory toward the recovery of a Sphagnum-dominated system that accumulates peat in the future. Intervention is therefore recommended, for example by blocking still active drainage ditches. In the peatlands of the other two regions, Sphagnum had a high initial cover and remained dominant ten years later. However, species typically found in hummocks gained relative importance vs. those associated to hollows. More time is needed to decide whether these sites could be left unmanaged as they have remained after their abandonment 35 years ago.
- PublicationAccès libreCloudberry cultivation in cutover peatland : improved growth on less decomposed peat.(Agricultural Institute of Canada, 2015-05-01) Rochefort, Line; Lapointe, Line; Bussières, JulieLa culture de la chicouté est sérieusement évaluée comme une option de réhabilitation des tourbières après récolte de la tourbe à des fins horticoles. Outre le gain en termes de valeur écologique et économique de ces sites, la culture de la chicouté pourrait augmenter le rendement en fruits et faciliter la récolte des fruits par rapport à la récolte en tourbières naturelles. Des études antérieures ont montré une croissance initiale lente qui a été provisoirement attribuée aux caractéristiques du substrat. Des expériences sur le terrain et en serres ont donc été mises en place pour mieux caractériser l'effet de différents substrats combinée aux techniques de restauration, sur la croissance des clones mâles et femelles. La chicouté a présenté une meilleure croissance en tourbe fibrique moins décomposée (H1–H3) qu'en tourbe mésique plus décomposée. La restauration devrait donc précéder la mise en culture de la chicouté de quelques années, afin de planter les rhizomes dans la couche de tourbe fibrique nouvellement accumulée. Les clones mâles produisent des feuilles plus grandes et plus de ramets par rhizome que les clones femelles en conditions communes de croissance. Les différences observées entre les sexes sont donc d'ordre génétique plutôt qu'environnemental. De plus, nous avons observé que les clones semblent particulièrement sensibles à la présence d'aluminium. En conclusion, le niveau de décomposition de la tourbe apparaît comme un des facteurs déterminant le succès de plantations de chicouté.