References of "Mahy, Grégory"
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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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See detailSocio-economic survey on invasive plants and ornamental horticulture in Belgium
Halford, Mathieu ULg; Heemers, Leen; Mathys, Catherine et al

Report (2011)

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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

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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 ▲]

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See detailClimatic and Anthropogenic Impacts on African Ecosystems "CLANIMAE" - Final Report
Verschuren, Dirk; Plisnier, Pierre-Denis; Cocquyt, Christine et al

Report (2011)

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See detailPatterns of hybridization and hybrid survival in the invasive alien Fallopia complex (Polygonaceae)
Saad, Layla ULg; Tiébré, Marie-Solange; Hardy, Olivier et al

in Plant Ecology and Evolution (2011), 144(12-18),

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels ... [more ▼]

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels has been experimentally demonstrated. Extensive genetic variation has also been observed among hybrids in the field. However, what makes a certain hybridization event of evolutionary importance is still the subject of speculation considering the invasive potential of hybrid Fallopia. Aims -- The present study examined landscape scale patterns of interspecific hybridization within the alien invasive Fallopia complex, and tested whether cold winter might act as selective agent for hybrid survival. Methods -- Eighty seeds per clone were collected from four taxa (F. japonica, F. sachalinensis, F. aubertii, and F. xbohemica) and sown in greenhouse and outdoor conditions. Ploidy levels of the resulting seedlings were determined by flow cytometry at early stages of seedling growth and compared to those of mature clones present in the same landscapes. Key results -- The four studied taxa were involved in interspecific hybridization patterns. Seedlings resulting from hybridization had a large range of ploidy levels, including aneuploid and euploid progeny, and polyploid levels that were not observed in mature clones. Cold winter had a negative effect on germination success. However, a comparison of ploidy levels of seedlings that survived the cold winter with those grown under greenhouse conditions indicated that cold winter was not a significant selection agent for particular ploidy levels. Conclusions -- Our results stress the importance of interspecific hybridization and polyploidization events in generating invasive hybrids in the alien Fallopia spp complex. Cold winter represents a selection agent for the survival of early stages of progeny but does not explain the discrepancies in ploidy levels between produced seedlings and currently occurring mature clones. [less ▲]

Detailed reference viewed: 78 (14 ULg)
See detailNos plans d’eau n’y échappent pas : les plantes amphibies invasives…
Delbart, Emmanuel ULg; Mahy, Grégory ULg

Article for general public (2011)

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See detailDu coto sur nos coteaux. Une espèce exotique à tenir à loeil!
Piqueray, Julien ULg; Vanderhoeven, Sonia; Halford, Mathieu ULg et al

Article for general public (2011)

Detailed reference viewed: 21 (8 ULg)
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See detailPlantons autrement: Code de conduite sur les plantes invasives (dépliant de vulgarisation)
Halford, Mathieu ULg; Heemers, Leen; Mathys, Catherine et al

Learning material (2011)

Detailed reference viewed: 11 (1 ULg)