References of "Mahy, Grégory"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailIdentité et écologie des espèces forestières commerciales d'Afrique Centrale: le cas de Milicia spp.
Daïnou, Kasso ULg; Doucet, Jean-Louis ULg; Sinsin, Brice et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16

Le terme iroko regroupe les deux espèces du genre africain Milicia et désigne le bois qui en est dérivé. Malgré une importance économique reconnue depuis plus de deux siècles et une diminution sensible ... [more ▼]

Le terme iroko regroupe les deux espèces du genre africain Milicia et désigne le bois qui en est dérivé. Malgré une importance économique reconnue depuis plus de deux siècles et une diminution sensible des densités de population du fait de l'exploitation, les connaissances scientifiques utiles à la gestion durable de l'iroko font défaut, particulièrement en Afrique Centrale. L'existence même d'une spéciation au sein du genre Milicia mérite d'être revérifiée: les caractères utilisés pour séparer les deux taxons M. excelsa (Welw.) C.C. Berg et M. regia (A. Chev.) C.C. Berg sont peu consistants et une révision de ces traits distinctifs permettrait de réétudier le niveau de vulnérabilité des populations de Milicia spp., et donc de revoir les stratégies de gestion de ce groupe taxonomique. M. regia n'a fait l'objet que de rares études écologiques tandis que M. excelsa, plus largement distribuée, a retenu l'attention scientifique en Afrique de l'Ouest, dans une certaine mesure. Dans tous les cas, les traits d'histoire de vie conditionnant la diversité génétique et le taux de régénération naturelle méritent d'être identifiés ou mieux décrits. En particulier, les connaissances existantes sur les populations reproductrices, les facteurs régulant la floraison, les patrons de fructification et de dispersion des diaspores, ainsi que d'autres caractères qui amènent à décrire l'iroko comme un arbre pionnier (besoins en lumière, dormance des graines) devraient être mieux documentés. Enfin, la dynamique même des populations naturelles de juvéniles devra également être mieux caractérisée. En l'absence de données fines en écologie, la durabilité de nombreuses ressources ligneuses commerciales est tributaire d'actions sylvicoles, lesquelles peuvent être coûteuses et ne pas être garanties sur le long terme. [less ▲]

Detailed reference viewed: 105 (23 ULg)
Full Text
See detailBiodiversity action plans: Kabwelunono [1] and Shimbidi. Proposal: long version
Seleck, Maxime ULg; Lebrun, Julie ULg; Ilunga wa Ilunga, Edouard et al

Report (2011)

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
See detailSoil-plants relations diversity in extreme ecosystems and implications for restoration: the case of the cupriferous vegetation, in Katanga, D.R. Congo
Seleck, Maxime ULg; Lebrun, Julie ULg; Piqueray, Julien ULg et al

Conference (2011, June 13)

Katangan copper and cobalt hills in the D. R. Congo are isolated ecosystems on highly toxics substrates (>10.000 ppm Cu, with strongly marked gradients). As a result, those outcrops host singular vegetal ... [more ▼]

Katangan copper and cobalt hills in the D. R. Congo are isolated ecosystems on highly toxics substrates (>10.000 ppm Cu, with strongly marked gradients). As a result, those outcrops host singular vegetal communities – with a diversity of specialized metallophytes species – related to soil metals content. Recent resumption of mining activities in the area threatens those ecosystems. To allow the restoration of those communities a fine understanding of the relationship maintained with the edaphic factors is required, as well as a characterization of the intra and inter sites variation. Three outcrops have been studied on the basis of a systematic grid, following the a priori trace elements gradient. In 1m² quadrats, a composite soil sample (0-15 cm depth) was taken and the cover (%) of each species of vascular plants was recorded. Soils were analyzed for pH, C, N, and bioavailables Cu, Co, Zn, Mn, Fe, K, Mg, Ca and P. The cluster analysis and Canonical Correspondence Analysis show that different sites present different soil conditions and vegetation. Concentrations in Cu are an important explicative factor of the flora’s variation but gradients in others edaphic parameters (pH, Mg, Mn, K, Ca) appear to be essential. However, parameters explaining the diversity of communities vary from one site to another indicating a great diversity of those ecosystems and the need to develop restoration strategies relevant for each site. [less ▲]

Detailed reference viewed: 24 (11 ULg)
Peer Reviewed
See detailImpact of population history on Viola calaminaria conservation, an endemic species of calamine sites
Bizoux, Jean-Philippe ULg; Mahy, Grégory ULg

Conference (2011, June)

The zinc violet, Viola calaminaria is a threatened species, endemic to calamine sites in Belgium and West Germany. Since the end of 19th century, the V. calaminaria habitat network have exhibited a huge ... [more ▼]

The zinc violet, Viola calaminaria is a threatened species, endemic to calamine sites in Belgium and West Germany. Since the end of 19th century, the V. calaminaria habitat network have exhibited a huge dynamics, with creation of new habitats resulting from industrial pollution and destruction of habitats by urbanisation and site remediation. In the present study, we analysed the effect of population history (recent/ancient population) on genetic diversity, fitness and reproductive success in order to discuss conservation strategies for the species. Recently founded populations exhibited similar level of genetic diversity (Hs) as ancient populations but showed a lower genetic differentiation among population (Fst). No indication of strong founder effects in recently established populations was detected. Plant fitness (seed set and germination percentage) was higher in recent populations while other reproductive traits (vegetative density, flower density, fructification percentage) did not differ according to population history. Results suggest that the creation of habitats through human activities can provide new opportunities for conservation of this species. In increasingly disturbed environments, this indicates that, at least for some species, conservation strategies should not focus solely on traditional and natural habitats but also consider the potential benefits offered by modified landscapes. [less ▲]

Detailed reference viewed: 25 (5 ULg)
Peer Reviewed
See detailSoil seed bank of calamine sites in Belgium: what could be learned for original metallophytes communities restoration?
Bizoux, Jean-Philippe ULg; Mahy, Grégory ULg

Conference (2011, June)

Metalliferous sites often host rare, ecologically endemic taxa adapted to high levels of heavy metals in soils. In Belgium, these sites correspond to Calamine sites. They are often considered as waste ... [more ▼]

Metalliferous sites often host rare, ecologically endemic taxa adapted to high levels of heavy metals in soils. In Belgium, these sites correspond to Calamine sites. They are often considered as waste ground dangerous for human health and public authorities are inclined to promote site remediation by fertilization, ground supply or removal, building ... In the present study, we analysed the seed bank of two ancient calamine sites in order to precise strategies for restoration of calamine original communities by top soil removal and perturbation. Composite soil samples were taken in 5 facies in two sites corresponding to different association. Cores were divided in three layers: litter, 0-5 cm, 5-10 cm. The total number of taxa was 24 taxa at Theux and 15 at Schmalgraf. The most abundant species (68%) are Agrostis capillaries and Viola calaminaria. Seed bank composition appeared different between facies except for three species. The seed bank was dominated by pseudo metallophytes species in Schmalgraf and by metallophytes or other species in Theux. The majority of the species didn’t present significant difference of number of seed between the three layers, except seven species (A. capillaries, V. calaminaria, Silene vulgaris, Minuertia verna, ...) with significant lower number of seed in the layer 5-10 cm. Our result showed that soil seed bank composition refl ect well vegetation communities of the two sites. In addition, because pseudo-metallophyte species as Agrostis capillaries dominated seed bank when they were present in the vegetation, soil removal must be used with parsimony to restore original communities. [less ▲]

Detailed reference viewed: 61 (6 ULg)
Full Text
Peer Reviewed
See detailDynamics of black-grass populations depending on the sowing time of winter wheat
Vandersteen, Joëlle; Jaunard, Delphine ULg; Mahy, Grégory ULg et al

in Communications in Agricultural and Applied Biological Sciences (2011, May 24), 76(3), 485-490

Currently, economic, agronomic and environmental concerns, lead to reduce use of herbicides. This reduction can be help by cultural measures like delay of the sowing date. Four sowing dates of winter ... [more ▼]

Currently, economic, agronomic and environmental concerns, lead to reduce use of herbicides. This reduction can be help by cultural measures like delay of the sowing date. Four sowing dates of winter wheat from 15th of October to 26th of November were tested. Dynamic of black-grass populations and their reproduction rate were assessed as well as dynamic of winter wheat for each date. Delay of sowing could significantly reduce reproduction rate of blac-grass. It was shwn that the emergence rate (pl/m²), but also number of ears per plant and number of seeds per ear of black-grass decreased significantly with the sowing date. This reproduction of seeds productioin already is from sixty per cent of a delay of two weeks sowing. [less ▲]

Detailed reference viewed: 53 (13 ULg)
Full Text
See detailSocio-economic survey on invasive plants and ornamental horticulture in Belgium
Halford, Mathieu ULg; Heemers, Leen; Mathys, Catherine et al

Report (2011)

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailRelation between Cobalt Fractionation and its Accumulation in Metallophytes from South of Central Africa
Faucon, Michel-Pierre; Colinet, Gilles ULg; Jitaru, P et al

in Mineralogical Magazine (2011), 75(3), 832

Detailed reference viewed: 14 (2 ULg)
Full Text
Peer Reviewed
See detailConservation of an endemic metallophyte species: effect of population history and vegetative density on the reproductive success of Viola calaminaria
Bizoux, Jean-Philippe ULg; cristofoli, sara; Piqueray, Julien ULg et al

in Journal for Nature Conservation (2011), 19

Demographic studies that monitor population dynamics are an essential component in establishing conservation strategies. The conventional view that human disturbance results in negative effects to species ... [more ▼]

Demographic studies that monitor population dynamics are an essential component in establishing conservation strategies. The conventional view that human disturbance results in negative effects to species and habitats is countered by the fact that some anthropogenic activities result in the origin of new habitat opportunities for species. Faced with an increase in European restoration programs, studies that assess the variability in traits conferring reproductive success among populations is particularly relevant to rare species conservation and further improves our knowledge to achieve restoration success. In the present study, we evaluated reproductive success variation (flower density, percent fructification and seed set) in Viola calaminaria, a rare endemic metallophyte, in relationship to population origins (ancestral or recent habitat), plant density and habitat structure. Results indicated that seed set varied significantly among ancestral and recently established populations, with recent populations exhibiting increased seed set (P < 0.05). Habitat structure did not influence species reproductive success. A positive significant correlation was detected between vegetative and flower density (P < 0.001). Results suggested that population origin (ancestral or recent) and local vegetative density was more important than habitat structure on reproductive success in V. calaminaria. In addition, we demonstrated that V. calaminaria populations distributed in habitats recently created by anthropogenic activity exhibited similar or higher reproductive success than populations from ancestral sites. These results are noteworthy as they show that anthropogenic activities can create new favourable habitats for some rare species. [less ▲]

Detailed reference viewed: 59 (20 ULg)
Full Text
See detailClimatic and Anthropogenic Impacts on African Ecosystems "CLANIMAE" - Final Report
Verschuren, Dirk; Plisnier, Pierre-Denis; Cocquyt, Christine et al

Report (2011)

Detailed reference viewed: 21 (0 ULg)