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See detailCarrières & Biodiversité - Les pelouses sèches
Harzé, Mélanie ULg; Boisson, Sylvain ULg; Halford, Mathieu ULg et al

Learning material (2014)

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See detailCarrières & Biodiversité - Les plantes invasives
Halford, Mathieu ULg; Boisson, Sylvain ULg; Harzé, Mélanie ULg et al

Learning material (2014)

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See detailCarrières & Biodiversité - Les plans d'eau
Boisson, Sylvain ULg; Harzé, Mélanie ULg; Halford, Mathieu ULg et al

Learning material (2014)

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See detailCarrières & Biodiversité - Les falaises et éboulis
Seleck, Maxime ULg; Boisson, Sylvain ULg; Harzé, Mélanie ULg et al

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See detailCarrières & Biodiversité - Les arènes minérales
Piqueray, Julien; Boisson, Sylvain ULg; Halford, Mathieu ULg et al

Learning material (2014)

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See detailExtent of intra-population functional variability along a local environmental gradient for four calcareous grasslands species
Harzé, Mélanie ULg; Monty, Arnaud ULg; Mahy, Grégory ULg

Conference (2013, August 19)

In the last few years, an increasing body of evidence has highlighted the role of functional traits as reliable predictors of species resistance to disturbance and response to environmental gradients ... [more ▼]

In the last few years, an increasing body of evidence has highlighted the role of functional traits as reliable predictors of species resistance to disturbance and response to environmental gradients. However, most studies focused on functional comparisons at the interspecific level while intraspecific functional trait variation has received remarkably little attention. As intraspecific traits variability is a necessary condition for species to adapt to environmental changes, studying intraspecific functional traits variation along environmental gradients is a major issue in a context of global change. The aim of our study was to evaluate the extent of intraspecific functional variability of four species along an environmental gradient of water stress at a local scale and to compare species response to the gradient. Calcareous grasslands species are present along a xeric gradient from mesophilous to xerophilous grasslands. Changes of exposure, slope and soil depth lead to differences of water availability for plants along the gradient. We measured the maximum vegetative height (MVH), the specific leaf area (SLA, one side area of a fresh leaf divided by its oven-dry mass) and the leaf dry matter content (LDMC, leaf oven-dry mass divided by its water-saturated fresh mass) on randomly selected individuals along a gradient of xericity on three study sites located in south Belgium. Functional traits were measured on about 60 individuals per site and per species. The soil depth was measured around each individual. The exposure and the slope were measured in order to calculate a heat load index for each individual. The extent of local intraspecific functional variability of our data was compared to data covering the species European range. Results are species dependent but for some study species intraspecific functional variability at local scale is not negligible compared to European data. Species functional responses to the gradient (soil depth and heat load index) showed a decrease in SLA and MVH and an increase in LDMC with increasing xericity for all study species. Response extent was species dependent. Main implications for species resistance to disturbance and climate change adaptation will be discussed. [less ▲]

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See detailEvaluation du succès de restaurations de pelouses calcicoles de la vallée du Viroin : densité en individus et succès reproducteur de deux espèces cibles.
Harzé, Mélanie ULg

Master's dissertation (2010)

Calcareous grasslands are local biodiversity « hotspots ». Unfortunately, these exceptional ecosystems have undergone a drastic fragmentation since the abandonment of traditional agro pastoral practices ... [more ▼]

Calcareous grasslands are local biodiversity « hotspots ». Unfortunately, these exceptional ecosystems have undergone a drastic fragmentation since the abandonment of traditional agro pastoral practices. Consequently, many calcareous grassland species are now in danger. In Belgium, since 1990, many hectares of these habitats have been restored to reassemble remaining fragments of calcareous grasslands. The main goal of this work is to participate at the scientific evaluation of calcareous grasslands restoration which took place in the Viroin valley (Namur, Belgium). To reach this goal, information about global and local densities of 2 grasslands species (Helianthemum nummularium and Sanguisorba minor) have been collected on 6 working zones (2 reference grasslands, 2 restored in 1990 and 2 restored in 2006) situated on 2 different sites. Reproductive success traits have been measured on 120 individual samples of each species. Moreover, individuals’ size parameters and some environmental data (soil depth and vegetation structure) have been collected. Results show that global and local densities are lower on recently restored grasslands for both species studied. On the other hand, older restorations and reference grasslands are not significantly different. With regards to the reproductive success of species, individuals on grasslands restored in 2006 have the best results. They produce more flowers, or inflorescences, and more seeds. Differences observed for individuals’ reproductive success have their more probable cause in vegetation structure. The vegetation in the zones that have been restored more recently is more open as the shrubs and trees layer is lower. [less ▲]

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