References of "Mahy, Grégory"
     in
Bookmark and Share    
See detailPlant species extinction debt in a biodiversity hotspot: community and species approaches
Piqueray, Julien ULg; Bisteau, Emmanuelle; Cristofoli, Sara et al

Conference (2009, April)

Detailed reference viewed: 9 (1 ULg)
See detailEnvironmental Controls on the Distribution of Aquatic Macrophytes in Ugandan Crater-lakes
Lebrun, Julie ULg; Mahy, Grégory ULg

Poster (2009, March 27)

This research is part of an integrated paleoecological project which aims at coupling reconstructions of past vegetation and water-quality changes with climate variability. Crater-lakes from East Africa ... [more ▼]

This research is part of an integrated paleoecological project which aims at coupling reconstructions of past vegetation and water-quality changes with climate variability. Crater-lakes from East Africa are favourable to the conservation of proxy indicators such as plant macrofossils used to reconstruct the lake ecosystem. The study of modern macrophytic communities related to present environmental parameters was the first step of this research. Phytosociologic and environmental data were collected in 36 crater-lakes in South-western Uganda. Species abundance and habitat conditions were described in 216 relevés arranged along transects from the lakeshore to the depth limit of aquatic plant development. A cluster analysis identified 8 macrophytes communities and their indicator species were highlighted. Combining two levels of analysis (lake or relevé) with different kind of ordinations (CA and CCA), main parameters explaining community variability were conductivity, pH, Human Impact index, vegetation zonation and productivity (Chlorophyll-a and total nitrogen). Multiple species response curves to environmental parameters were performed to assess the ecological amplitude at the individual level and select species with a good proxy-indicator value. These results give some trends about the ecology of macrophytes communities and the ecological significations of macrofossils. [less ▲]

Detailed reference viewed: 52 (1 ULg)
Full Text
Peer Reviewed
See detailAn explicit test for the contribution of environmental maternal effects to rapid clinal differentiation in an invasive plant
Monty, Arnaud ULg; Lebeau, Julie; Meerts, Pierre et al

in Journal of Evolutionary Biology (2009), 22(5), 917-926

Population differentiation of alien invasive plants within their non-native range has received increasingly more attention. Common gardens are typically used to assess the levels of genotypic ... [more ▼]

Population differentiation of alien invasive plants within their non-native range has received increasingly more attention. Common gardens are typically used to assess the levels of genotypic differentiation among populations. However, in such experiments, environmental maternal effects can influence phenotypic variation among individuals if seed sources are collected from field populations under variable environmental regimes. In the present study, we investigated the causes of an altitudinal cline in an invasive plant. Seeds were collected from Senecio inaequidens (Asteraceae) populations along an altitudinal gradient in southern France. In addition, seeds from the same populations were generated by intra-population crossings in a climatic chamber. The two seed lots were grown in a common garden in Central Belgium to identify any evidence of environmentally induced maternal effects and/or an altitudinal cline in a suite of life-history traits. Results failed to detect any environmental maternal effects. However, an altitudinal cline in plant height and above-ground biomass was found to be independent of the maternal environment. [less ▲]

Detailed reference viewed: 41 (10 ULg)
Full Text
Peer Reviewed
See detailClinal differentiation during invasion: Senecio inaequidens (Asteraceae) along altitudinal gradients in Europe
Monty, Arnaud ULg; Mahy, Grégory ULg

in Oecologia (2009), 159(2), 305-315

The dynamics of plant population differentiation may be integral in predicting aspects of introduced species invasion. In the present study, we tested the hypothesis that European populations of Senecio ... [more ▼]

The dynamics of plant population differentiation may be integral in predicting aspects of introduced species invasion. In the present study, we tested the hypothesis that European populations of Senecio inaequidens (Asteraceae), an invasive species with South African origins, differentiated during migration from two independent introduction sites into divergent altitudinal and climatic zones. We carried out 2 years of common garden experiments with eight populations sampled from Belgian and ten populations from French altitudinal transects. The Belgian transect followed a temperature and precipitation gradient. A temperature and summer drought gradient characterized the French transect. We evaluated differentiation and clinal variation in plants germinated from field-collected seed using the following traits: days to germination, days to flowering, height at maturity, final plant height and aboveground biomass. Results showed that S. inaequidens populations differentiated in growth traits during invasion. During the 1st year of sampling, the results indicated clinal variation for growth traits along both the Belgium and French altitudinal transects. Data from the 2nd year of study demonstrated that with increasing altitude, a reduction in three growth traits, including plant height at maturity, final plant height and aboveground biomass, was detected along the French transect, but no longer along the Belgian one. Phenological traits did not exhibit a clear clinal variation along altitudinal transects. The possible evolutionary causes for the observed differentiation are discussed. [less ▲]

Detailed reference viewed: 73 (15 ULg)
Full Text
See detailMéthodes de gestion des principales plantes invasives en zones humides - 3 ème partie
pieret, Nora; Delbart, Emmanuel ULg; Vanderhoeven, SONIA ULg et al

in Silva Belgica (2009)

Detailed reference viewed: 45 (6 ULg)
Full Text
See detailHOW TO MAKE NATURA 2000 WORK PROPERLY? : SOCIO-ECONOMIC, LEGAL AND ECOLOGICAL MANAGEMENT : "SELNAT"
Grogna, Valérie; Mahy, Marie; Meuris, Steve et al

Report (2009)

This report includes results obtained from the SELNAT research project, conducted between February 2006 and January 2008, under the auspices of the Belgian Science Policy. The principal subject of this ... [more ▼]

This report includes results obtained from the SELNAT research project, conducted between February 2006 and January 2008, under the auspices of the Belgian Science Policy. The principal subject of this project is the implementation of Natura 2000. The Natura 2000 network of protected areas, made up of sites designated under the Community Birds (BD) and Habitats Directives (HD), is a key pillar of action for the conservation of biodiversity (European Commission, 2008). It is central to achieve the commitment to reverse the decline of biodiversity in the European Union by the year 2010 made at the European Council meeting in Gothenburg in June 2001. It aims at sustainable conservation of habitats and species of community importance, taking into account (i) economic, social and cultural requirements and (ii) regional and local circumstances. Central to the Directives is the creation of a Europe-wide ecological network of protected sites – the Natura 2000 Network – which is destined to conserve over a thousand rare, threatened and endemic species and some 220 Natural habitats listed in their annexes. Around 24,000 sites have been included in the Network so far. (European Commission, 2008) Now that the network set-up is nearing completion, there is a need to increase the focus on the active management of the sites so as to ensure long-term conservation and the achievement of the economic and social objectives of the network (CEE, 2004.) This in turn also raises the question of finding the appropriate management strategy, instruments and sufficient financing (at all levels). The principal question for Member States is how to manage Natura 2000 sites to reach the (juridical fixed) ecological targets in the most cost-efficient way, taking into account economic and social objectives and constraints. Ecologists and nature organisations often start from an techno-ecocentric paradigm: ‘How to conserve and manage species and habitats?’, in order to tackle the question mentioned above. The paradigm starts from the opinion that ‘diversity of species and habitats’ is important as such (while this is believed to be important for several reasons). This approach has been criticised lately for being based on a too narrow set of values. It has not provided enough opportunities for combining nature conservation with other forms of land use such as agriculture, forestry or tourism. In several countries this led to difficulties as regards the co-operation of local stakeholders (Jongman & Kristiansen, 1998). On the other hand, the current biodiversity crisis is a direct result of the way in which society has chosen to interact with its Natural environment. If the causes of the problem are social, it stands to reason that the policies striving to solve the problem will need to be based on a solid understanding of social structures and processes, if they are to have any effect. In this research project we tried to study the management of Natura 2000 sites from a ‘sustainability’ paradigm, instead of from the ecocentric paradigm. The central research question is therefore formulated as ‘How to manage Natura 2000 properly, to contribute to a (local) sustainable society?’ With this research we hope to give decision-makers new insights on the economic, social, and environmental consequences of Natura 2000 management and to guide them in the development of more adequate and sustainable policies for the management of Natura 2000-sites. In the first chapter the general objectives and approach of this project are described. The second chapter gives an overview of some of the current bottlenecks for nature conservation and Natura 2000. The results of the research on the elaboration of strategies for Natura 2000 sites are summarizes in chapter tree. Conclusions and recommendations are presented in the last chapter. More information on the research is documented in the different appendixes. During the research, we benefited from contacts with many persons, and more especially in the scope of a Users’ Committee. Besides the representatives of the Belgian Science Policy, we would like to thank all members of the Users’ Committee, among which those who supported us and/or participated in one or several of the meetings, [less ▲]

Detailed reference viewed: 75 (1 ULg)
Full Text
See detailMéthodes de gestion des principales plantes invasives en zones humides - 2 ème partie
Pieret, Nora; Delbart, Emmanuel ULg; Vanderhoeven, SONIA ULg et al

in Silva Belgica (2009)

Detailed reference viewed: 45 (8 ULg)
Full Text
Peer Reviewed
See detailMay rare metallophytes benefit from disturbed soils following mining activities ? The case of the Crepidorhopalon tenuis in Katanga (D.R. COngo)
Faucon, Michel Pierre; Parmentier, Ingrid; Collinet, Gilles et al

in Restoration Ecology (2009), 19

Detailed reference viewed: 163 (43 ULg)
Full Text
See detailL'inventaire des sites de grand intérêt biologique en Région wallonne.
Bisteau, Emmanuelle; Baugnée, Jean-Yves; Dufrêne, Marc ULg et al

in Forêt Wallonne (2009), 103

Detailed reference viewed: 45 (6 ULg)
See detailAppui à la création d’un diplôme d’études approfondies en biologie végétale et environnement à l’Université de Lubumbashi et remédiation multiscalaire des sols contaminés.
Ngongo Luhembwe, M; Bogaert, Jan ULg; Colinet, Gilles ULg et al

in Dahdouh-Guebas, F (Ed.) Proceedings of the Symposium on African Botany in Brussels (2009)

Detailed reference viewed: 19 (6 ULg)
Full Text
Peer Reviewed
See detailSpatial genetic structure in Milicia excelsa (Moraceae) indicates extensive gene dispersal in a low-density wind-pollinated tropical tree
Bizoux, Jean-Philippe ULg; Daïnou, Kasso ULg; Bourland, Nils ULg et al

in Molecular Ecology (2009), 18

In this study, we analysed spatial genetic structure (SGS) patterns and estimated dispersal distances in Milicia excelsa (Welw.) C.C. Berg (Moraceae), a threatened windpollinated dioecious African tree ... [more ▼]

In this study, we analysed spatial genetic structure (SGS) patterns and estimated dispersal distances in Milicia excelsa (Welw.) C.C. Berg (Moraceae), a threatened windpollinated dioecious African tree, with typically low density ( 10 adults ⁄km2). Eight microsatellite markers were used to type 287 individuals in four Cameroonian populations characterized by different habitats and tree densities. Differentiation among populations was very low. Two populations in more open habitat did not display any correlation between genetic relatedness and spatial distance between individuals, whereas significant SGS was detected in two populations situated under continuous forest cover. SGS was weak with a maximum Sp-statistic of 0.006, a value in the lower quartile of SGS estimates for trees in the literature. Using a stepwise approach with Bayesian clustering methods, we demonstrated that SGS resulted from isolation by distance and not colonization by different gene pools. Indirect estimates of gene dispersal distances ranged from rg = 1 to 7.1 km, one order of magnitude higher than most estimates found in the literature for tropical tree species. This result can largely be explained by life-history traits of the species. Milicia excelsa exhibits a potentially wideranging wind-mediated pollen dispersal mechanism as well as very efficient seed dispersal mediated by large frugivorous bats. Estimations of gene flow suggested no major risk of inbreeding because of reduction in population density by exploitation. Different strategy of seed collection may be required for reforestation programmes among populations with different extent of SGS. [less ▲]

Detailed reference viewed: 117 (20 ULg)
Full Text
See detailFiches descriptives des principales espèces de plantes invasives: Azolla filiculoides
Pieret, Nora; Delbart, Emmanuel ULg; Mahy, Grégory ULg

Learning material (2009)

Detailed reference viewed: 11 (1 ULg)
Full Text
See detailFiches descriptives des principales espèces de plantes invasives: Ludwigia spp.
Pieret, Nora; Delbart, Emmanuel ULg; Mahy, Grégory ULg

Learning material (2009)

Detailed reference viewed: 49 (1 ULg)
Full Text
See detailFiches descriptives des principales espèces de plantes invasives: Lagarosiphon major
Pieret, Nora; Delbart, Emmanuel ULg; Mahy, Grégory ULg

Learning material (2009)

Detailed reference viewed: 30 (3 ULg)
Full Text
See detailFiches descriptives des principales espèces de plantes invasives: Crassula helmsii
Pieret, Nora; Delbart, Emmanuel ULg; Mahy, Grégory ULg

Learning material (2009)

Detailed reference viewed: 23 (2 ULg)
Full Text
See detailFiches descriptives des principales espèces de plantes invasives: Egeria densa
Pieret, Nora; Delbart, Emmanuel ULg; Mahy, Grégory ULg

Learning material (2009)

Detailed reference viewed: 28 (2 ULg)