References of "Mahy, Grégory"
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See detailTyranny of Trees in Global Climate Change Mitigation
Veldman, Joseph W.; Overbeck, Gerhard; Negreiros, Daniel et al

in Science (in press)

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See detailToward and old-growth concept for grasslands, savannas, and woodlands
Veldman, Joseph W; Buisson, Elise; Durigan, Giselda et al

in Frontiers in Ecology and the Environment (in press)

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See detailResponse of plant functional traits during the restoration of calcareous grasslands from forest stands
Piqueray, Julien; Ferroni, Lucia; Delescaille, Louis-Marie et al

in Ecological Indicators (2015)

In this survey, we studied the response of plant functional traits to calcareous grassland restoration in the Calestienne region, Southern Belgium (restoration protocol: forest clear-cutting followed by ... [more ▼]

In this survey, we studied the response of plant functional traits to calcareous grassland restoration in the Calestienne region, Southern Belgium (restoration protocol: forest clear-cutting followed by grazing at all sites). We considered traits related to dispersal, establishment, and persistence that integrate the main challenges of plants to re-establish and survive in restored areas. Functional traits were compiled from databases and compared among (i) pre-restoration and young restoration forests; (ii) restoration areas of different ages; and (iii) old restorations and reference grasslands. The following questions were addressed: (i) What is the early response (2-4 years) in terms of plant functional trait following one restorative clear-cut event? (ii) What plants functional trait responses occur from restorative management (i.e. sheep and goat grazing)? (iii) Which differences still persist between the oldest restored parcels (10-15 years), and the historical reference grasslands? Forest clear-cuts induced several changes among functional traits, including decreased mean seed mass and certain vegetative traits (i.e. decreased phanerophytes, branching species; and increased short lifespan species i.e. annuals and biennials). During restorative management, clonal, epizoochorous and autumn germinating species were favored. Despite numerous other changes during this phase, many differences remained compared to reference grasslands. In particular, geophytes, mycorrhizal and evergreen species abundance were not approaching reference grassland values. The observed pattern helped to draw inferences on the possible mechanisms operating under vegetation recovery following restorative forest clear-cut and subsequent management were identified and described in this study. Results indicated grazing was an important factor, which increased epizoochorous species, and autumn germinating taxa that filled niches in vegetation opened by summer grazing animals. Finally, differences between old restoration and reference grasslands emphasized that management should focus on reduction in soil fertility, and geophyte rhizomatous grasses. Long-term monitoring is vital to assess if management plans are effective in the complete restoration of species functional trait assemblages. [less ▲]

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See detailEtude de la flore spontanée de la carrière de Loën pour de futures restaurations - Résultats
Pitz, Carline ULg; Mahy, Grégory ULg; Monty, Arnaud ULg et al

Conference given outside the academic context (2014)

Ce projet a pour objectif de caractériser la flore recolonisant spontanément les zones xériques non exploitées récemment de la carrière de Loën, du point de vue de la diversité spécifique et de la ... [more ▼]

Ce projet a pour objectif de caractériser la flore recolonisant spontanément les zones xériques non exploitées récemment de la carrière de Loën, du point de vue de la diversité spécifique et de la fonctionnalité écologique. Les communautés végétales ont été caractérisées au sein du site de Loën (diversité alpha) et d’un ensemble d’autres carrières représentatives de la diversité des contextes géographiques des carrières calcaires en Région Wallonne (diversité béta). L’étude a montré que, sur des laps de temps de plusieurs décennies, un processus de succession écologique s’est mis en place au sein du site de Loën, mais que cette succession ne tend pas vers une formation typique de pelouse sèche. Les explications peuvent être d’une part, que la disponibilité et l’apport de graines de pelouses sèches avoisinantes est insuffisant, et d’autre part, que le contexte abiotique pourrait être plus favorable à d’autres types de végétations herbacées. Cette étude illustre que des expériences de semis seraient souhaitable afin de définir les objectifs de restauration de la carrière de Loën et des carrières qui se trouvent dans des situations comparables. [less ▲]

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See detailThe Eurogypsum list of biodiversity indicators: a tool to increase biodiversity capacity in the gypsum industry.
Pitz, Carline ULg; Mahy, Grégory ULg

Conference given outside the academic context (2014)

The resulting framework contains eleven indicators which are the most acceptable set of indicators for all the stakeholders. It answers to European legislation and strategies for biodiversity. It is ... [more ▼]

The resulting framework contains eleven indicators which are the most acceptable set of indicators for all the stakeholders. It answers to European legislation and strategies for biodiversity. It is intended to improve sustainability in the quarries and to help managing biodiversity, to allow setting up of appropriate reporting systems. The aim is to maintain the biodiversity status of the gypsum quarries. It is a flexible framework adaptable given the local context of each gypsum quarry in order to prove if a No Net Loss has been reached at a quarry’s scale. [less ▲]

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See detailGreen roofs and facades : toward food and biodiversity functions
Mahy, Grégory ULg; Jijakli, Haissam ULg

Scientific conference (2014, November 12)

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See detailDisentangling the sources of phenotypic variation in Ambrosia artemisiifolia L.: the role of seed traits
Ortmans, William ULg; Monty, Arnaud ULg; Mahy, Grégory ULg

Poster (2014, November 03)

When invading new environments, a plant invader may express new phenotypes as a result of different ecological and genetic processes. It includes phenotypic plasticity, local adaptation, environmental ... [more ▼]

When invading new environments, a plant invader may express new phenotypes as a result of different ecological and genetic processes. It includes phenotypic plasticity, local adaptation, environmental maternal effects, and genetic drift. The quantification of each of these factors is crucial in the study of biological invasions. Ambrosia artemisiifolia L. invasion success is strongly linked to seed characteristics (dispersal by human activities, long-lived soil seed bank, etc.). Known as an opportunist and a colonizer, the species is often limited by the competition from other plants. In the early stages of development, the seedlings can be quickly outcompeted and a rapid growth is therefore a major advantage. First, this study aims to analyze the seed traits variation, and to detect an impact of these traits on the early development of the seedling (environmental maternal effect). Second, we aimed to quantify the respective role of phenotypic plasticity, environmental maternal effect, local adaptation and genetic drift on seedlings phenotype. Variability of seeds from 3 geographical zones (Belgium – Centre of France – South of France) was assessed. We measured the seed variation in mass, length, width, circularity, and pigmentation. Seeds were disposed in growth chamber under two temperature treatments. After two months, we compared seedling phenotypic variation in germination time, height, aboveground biomass, belowground biomass, early competitive performance, and the final leaf area. We found a high variability of seed traits. Seeds were varying significantly among zones, populations, and parents, with more than 30% of the variation attributable to the mother plant identity. The main sources of seedling phenotypic variation appeared to be phenotypic plasticity and environmental maternal effect. No genetic differentiation was detected in this study. Seed mass was positively correlated to seedling biomass, early competitive performance, and the final leaf area. The relevance of traits reflecting environmental maternal effect is discussed. Phenotypic plasticity and seed characteristics appear to play a major role in the invasion success. [less ▲]

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See detailVegetative Regeneration Capacities of Five Ornamental Plant Invaders After Shredding
Monty, Arnaud ULg; Eugène, Marie; Mahy, Grégory ULg

in Environmental Management (2014)

Vegetation management often involves shredding to dispose of cut plant material or to destroy the vegetation itself. In the case of invasive plants, this can represent an environmental risk if the ... [more ▼]

Vegetation management often involves shredding to dispose of cut plant material or to destroy the vegetation itself. In the case of invasive plants, this can represent an environmental risk if the shredded material exhibits vegetative regeneration capacities. We tested the effect of shredding on aboveground and below-ground vegetative material of five ornamental widespread invaders in Western Europe that are likely to be managed by cutting and shredding techniques: Buddleja davidii (butterfly bush, Scrophulariaceae), Fallopia japonica (Japanese knotweed, Polygonaceae), Spiraea x billardii He´rincq (Billard’s bridewort, Rosaceae), Solidago gigantea (giant goldenrod, Asteraceae), and Rhus typhina L. (staghorn sumac, Anacardiaceae). We looked at signs of vegetative regeneration and biomass production, and analyzed the data with respect to the season of plant cutting (spring vs summer), the type of plant material (aboveground vs below-ground), and the shredding treatment (shredded vs control). All species were capable of vegetative regeneration, especially the belowground material. We found differences among species, but the regeneration potential was generally still present after shredding despite a reduction of growth rates. Although it should not be excluded in all cases (e.g., destruction of giant goldenrod and staghorn sumac aboveground material), the use of a shredder to destroy woody alien plant material cannot be considered as a general management option without significant environmental risk. [less ▲]

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See detailEtude de la flore spontanée de la carrière de Loën pour de futures restaurations - Rapport final
Pitz, Carline ULg; Mahy, Grégory ULg; Monty, Arnaud ULg et al

Report (2014)

Ce projet a pour objectif de caractériser la flore recolonisant spontanément les zones xériques non exploitées récemment de la carrière de Loën, du point de vue de la diversité spécifique et de la ... [more ▼]

Ce projet a pour objectif de caractériser la flore recolonisant spontanément les zones xériques non exploitées récemment de la carrière de Loën, du point de vue de la diversité spécifique et de la fonctionnalité écologique. Les communautés végétales ont été caractérisées au sein du site de Loën (diversité alpha) et d’un ensemble d’autres carrières représentatives de la diversité des contextes géographiques des carrières calcaires en Région Wallonne (diversité béta). L’étude a montré que, sur des laps de temps de plusieurs décennies, un processus de succession écologique s’est mis en place au sein du site de Loën, mais que cette succession ne tend pas vers une formation typique de pelouse sèche. Les explications peuvent être d’une part, que la disponibilité et l’apport de graines de pelouses sèches avoisinantes est insuffisant, et d’autre part, que le contexte abiotique pourrait être plus favorable à d’autres types de végétations herbacées. Cette étude illustre que des expériences de semis seraient souhaitable afin de définir les objectifs de restauration de la carrière de Loën et des carrières qui se trouvent dans des situations comparables. [less ▲]

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See detailRestoration of threatened metallophyte populations in Katanga (D.R. Congo): lessons learnt.
Le Stradic, Soizig ULg; Seleck, Maxime ULg; Le Brun, Julie et al

Conference (2014, August 05)

One of the current major challenges consists in integrating economic activities with environmental integrity and social concerns. One of the world’s largest concentrations of copper and cobalt deposits is ... [more ▼]

One of the current major challenges consists in integrating economic activities with environmental integrity and social concerns. One of the world’s largest concentrations of copper and cobalt deposits is located in Katanga (Democratic Republic of Congo) and represents an important source of income for the country. Unique communities and several endemic species are hosted on copper outcrops and are threatened by the extension of mining activities in the area. In theory, translocation or transplantation of structuring and/or endemic species is a suitable substitute to spontaneous succession and a good mean to rescue and conserve the more threatened species. Here we present briefly the global framework developed with a mining company in order to conserve and restore the biodiversity of Cu-Co communities, including, among others, translocation and transplantation of highly threatened species. We recorded low survival of translocated individuals. An alternative was then to produce seedlings of endemic and/or structuring species under nursery conditions for their later transplantation in degraded areas or for conservation purposes. However, the diversity of plant forms and life-forms found in such tropical area limited the production of many species. We highlighted that poor understanding of many of these tropical plants often hampered their regeneration and their use in restoration program. As already noticed, transplantation results are not always reported, especially in case of failure, while such results appear as even more important than successes and have to be presented. [less ▲]

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See detailTopsoil and community translocation as a mean to restore metallophyte communities of katangan copper hills (D.R. Congo)
Seleck, Maxime ULg; Le Stradic, Soizig ULg; Lebrun, Julie et al

Conference (2014, August 04)

One of the current major challenges consists in integrating economic activities with environmental integrity. One of the world’s largest concentrations of copper and cobalt deposits is located in Katanga ... [more ▼]

One of the current major challenges consists in integrating economic activities with environmental integrity. One of the world’s largest concentrations of copper and cobalt deposits is located in Katanga (Democratic Republic of Congo) and represents an important source of income for the country. Unique communities and several endemic species are hosted on copper outcrops and are threatened by the extension of mining activities in the area. In theory, translocation or transplantation of structuring and/or endemic species is a suitable substitute to spontaneous succession and a good mean to rescue and conserve the more threatened species. Here we present the global framework developed with a mining company in order to conserve and restore the biodiversity of Cu-Co communities, including, translocation and transplantation of highly threatened species. We recorded low survival of translocated individuals. An alternative was then to produce seedlings of native species under nursery conditions for their later transplantation in degraded areas or for conservation purposes. However, we highlighted that the diversity of plant forms found in such tropical area limited the production of many species and poor understanding of many of these tropical plants often hampered their regeneration and their use in restoration. Transplantation results are not always reported, especially in case of failure, while such results appear as even more important than successes and have to be presented. [less ▲]

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See detailIntraspecific variation of copper tolerance of four endemic plant species from the katangan Copperbelt (D. R. Congo)
Boisson, Sylvain ULg; garin, olivier; Seleck, Maxime ULg et al

Conference (2014, August 04)

Harsh ecosystems are at the origin of speciation processes in plant communities. In metalliferous areas, plants develop physiological adaptations to tolerate metal excesses which lead to high species and ... [more ▼]

Harsh ecosystems are at the origin of speciation processes in plant communities. In metalliferous areas, plants develop physiological adaptations to tolerate metal excesses which lead to high species and population diversity. South of the Katanga province (D.R. Congo), plant communities occur on soils with one of the world’s largest concentrations of copper and cobalt. More than 600 species including 54 endemics are distributed along a copper gradient (up to 10 000 mg kg-1 available Cu) and the populations are isolated on more than 100 copper hills scattered in miombo forest. In order to improve restoration strategies of threatened species, we aimed to identify intraspecific copper tolerance of 4 endemic plant species from katangan copper outcrops: Crotalaria cobalticola, Diplolophium marthozianum, Gladiolus ledoctei and Triumfetta welwitschii. Seeds were collected in 3 different populations in the katangan Copperbelt and sown according three soil contamination modalities: control (no addition of Cu), 100 mg kg-1 and 1000 mg kg-1 of Cu concentration using hydrated copper (II) sulfate. For each combination (species x populations x soils), we had 10 repetitions. For each population, sample of 5 seeds was weighed before seedling in pot in November 2013. One individual by pot was kept for measures. Height (cm), number of leaves, number of flowers and number of fruits were measured once a week during one rainy season. For all species, no significant difference of copper tolerance appeared between populations. In contrast, populations had distinct germination rate and growth rate, especially for T. welwitshii and D. marthozianum. C. cobalticola grew significantly better in highly contaminated soil than other soils. G. ledoctei did not show any significant difference between populations and soil treatments. [less ▲]

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See detailDeveloping a common Key Performance Indicators framework for biodiversity management in gypsum quarries throughout Europe for Eurogypsum
Pitz, Carline ULg; Mahy, Grégory ULg; Marlet, Christine

Conference (2014, August)

This study aimed to establish a common Key Performance Indicators (KPIs) framework to report biodiversity for the Gypsum Industry at the European level. An original approach of participatory process has ... [more ▼]

This study aimed to establish a common Key Performance Indicators (KPIs) framework to report biodiversity for the Gypsum Industry at the European level. An original approach of participatory process has been developed in order to integrate the different opinions and to reach a consensus framework between different stakeholders’ groups: Eurogypsum stakeholders, European and local authorities, universities and consulting offices, European and local associations for the conservation of nature and stakeholders from the mining sector. The strategy is based on five main steps: (i) To build a stakeholders’ network; (ii) ) To build a framework proposal to be submitted to stakeholders by selecting a maximum set of indicators based on the literature and reaching an agreement on indicators with Eurogypsum (Focus Group); (iii) Reaching a consensus framework with all the stakeholders and evaluating feasibility by a Delphi Policy survey, by the analysis of the Environmental Impact Assessments of the Gypsum Industry and by visiting three quarries; (iv) Final validation with Eurogypsum; (v) Creating indicators’ Factsheets and a Eurogyspum report to the destination of the public. The resulting framework contains eleven indicators which are the most acceptable set of indicators for all the stakeholders. It answers to European legislation and strategies for biodiversity. It is intended to improve sustainability in the quarries and to help managing biodiversity, to allow setting up of appropriate reporting systems. It is a flexible framework adaptable given the local context of each gypsum quarry in order to prove if a No Net Loss has been reached at a quarry’s scale. [less ▲]

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See detailNo performance reduction at the present northern edge of Ambrosia artemisiifolia L. invasion range
Ortmans, William ULg; Chauvel, Bruno; Monty, Arnaud ULg et al

Conference (2014, May 05)

Plant populations at range edges may exhibit reduction of performances and fitness. In the case of biological invasions, such a reduction could be associated with a slowing down of the spread and explain ... [more ▼]

Plant populations at range edges may exhibit reduction of performances and fitness. In the case of biological invasions, such a reduction could be associated with a slowing down of the spread and explain the non-naturalization of a species outside its present invasion range. Common ragweed (Ambrosia artemisiifolia L.) is an ideal model to investigate such processes, since it is invasive in France but not naturalized in northern countries, such as Belgium and the Netherlands. In this study, we test if the performances of ragweed populations vary among different invasion zones. Three populations were selected in each of four invasion zones in Western Europe: 1) French invasion area; 2) northern and 3) southern invasion edges; and 4) outside the invasion area (Belgium and Netherlands). Field performances (growth, reproduction, stress resistance) were recorded on 25 plants per population. Furthermore, the competition by the native flora was assessed around each plant. Generalized Linear Models were used to compare performance among invasion zones and populations, with competition as covariate. Regressions were also performed to assess the influence of climatic data on population performances. No evidence of decreasing performances was found at the edges of the invasion area, neither outside of it, suggesting that the invasion front has the potential to keep going northwards. Competition by native flora had a significant impact on stress resistance, but did not decrease reproduction or growth. These results are discussed in the light of other ongoing experiments in Belgium. [less ▲]

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See detailAlien plant species along watercourses in the Natura 2000 network
Monty, Arnaud ULg; Aimont, Hélène; Mahy, Grégory ULg

Conference (2014, May)

Natura 2000 is the centerpiece of EU nature and biodiversity policy. It is a European wide network of nature protection areas aiming at assuring the long-term survival of Europe's most valuable and ... [more ▼]

Natura 2000 is the centerpiece of EU nature and biodiversity policy. It is a European wide network of nature protection areas aiming at assuring the long-term survival of Europe's most valuable and threatened species and habitats. However, alien plants do not stop their spread at the border of protection areas and invasive plants are reported to threaten aquatic and riparian ecosystems. Our study aimed at assessing the plant invasion threat along watercourses within the Natura 2000 in Southern Belgium. A stratified random sampling, based on the natural region and the size of the watershed, was conducted. 187 sections of watercourses bank were visited between May and September 2013. For all recorded alien species, data were collected about local abundance, competitive impacts, regeneration potential and ecological conditions. 51 alien species were observed. Some were widespread (e.g. Impatiens glandulifera, with 17 % of linear banks invaded) whereas others were either rare or considered emergent alien species. Emergent species, showing low occurrence but high impact index, are appropriate target species for early detection programs and preventive management actions. Analyses showed that typical riparian species’ occurrence increased with the size of the watershed, indicating propagule pressure within protected areas through hydrochory. No link could be established between the presence of disturbance(s) and alien species in the considered N2000 sites. [less ▲]

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See detailEtude de la flore spontanée de la carrière de Loën pour de futures restaurations
Pitz, Carline ULg; Mahy, Grégory ULg; Monty, Arnaud ULg et al

Conference given outside the academic context (2014)

This project aims to characterize the flora that spontaneously recolonize non recently exploited areas in one group quarry (Loën) from the point of view of species diversity and ecological functionality ... [more ▼]

This project aims to characterize the flora that spontaneously recolonize non recently exploited areas in one group quarry (Loën) from the point of view of species diversity and ecological functionality. Plant communities will be compared with observed plant communities characterized in longest abandoned quarries in the same regions (same pool of potential species) and known plant communities of the dry grassland habitats reference. The project will establish the potential for restoration of dry grasslands in the study site and established for the quarry studied the basic principles of future restoration plans. [less ▲]

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See detailVariation des traits fonctionnels le long d’un gradient de cuivre et cobalt : contribution du remplacement d’espèces et de la variabilité intraspécifique
Delhaye, Guillaume; Violle, Cyril; Seleck, Maxime ULg et al

Conference (2014, April)

Les collines cuprocobaltifères du Katanga sont des lieux privilégiés pour étudier la variation des traits fonctionnels le long de gradients de stress métallique. Nous avons étudié la variation de six ... [more ▼]

Les collines cuprocobaltifères du Katanga sont des lieux privilégiés pour étudier la variation des traits fonctionnels le long de gradients de stress métallique. Nous avons étudié la variation de six traits à l’échelle des espèces et de la communauté le long d’un gradient de cuivre et cobalt. D’autres paramètres tels que la concentration en phosphore et l’humidité du sol covarient positivement avec la teneur en métal du sol. Les contributions relatives du remplacement d’espèces et de la variabilité intraspécifique à la variabilité totale des traits dans les communautés ont été déterminées. A l’échelle de la communauté, la hauteur et la surface foliaire diminuent alors que les valeurs des quatre autres traits augmentent le long du gradient. Les espèces montrent des réponses variées, généralement non significatives. Pour tous les traits, le remplacement d’espèce est le moteur principal de la variation au sein des communautés. La concentration en métal du sol implique des réponses variées sur les différents traits et les différentes espèces. Nous montrons que la concentration croissante en métal privilégie le remplacement d’espèce par rapport à la variation intraspécifique et que les espèces répondent par différentes stratégies de tolérance à la concentration en métal du le sol. La variation des traits à l’échelle des communautés est essentiellement le reflet d’un changement dans les abondances des différentes formes de vie. Les espèces à xylopodes sont dominantes sur sol pauvre en métal alors que les annuelles sont dominantes sur sol très enrichi. [less ▲]

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See detailLa carte blanche : Enjeux de la Politique agricole commune en Wallonie : une volonté de découpler nature et agriculture ?
Jacquemart, Anne-Laure; Dendoncker, Nicolas; Dufrêne, Marc ULg et al

Article for general public (2014)

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