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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 detailTesting coexistence of extinction debt and colonization credit in fragmented calcareous grasslands with complex historical dynamics
Piqueray, Julien ULg; Cristofoli, Sara; Bisteau, Emmanuelle et al

in Landscape Ecology (2011), 26

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. However, these ecosystems have suffered from fragmentation and destruction during the last century. We studied the ... [more ▼]

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. However, these ecosystems have suffered from fragmentation and destruction during the last century. We studied the response of calcareous grassland plant diversity to landscape changes in Belgium. Results indicated that high area loss (since 1965) old habitat patches exhibited an extinction debt inverse to low area loss old habitat patches, little depending on the area loss threshold (60%, 70%, 80% or 90%) considered for the distinction between the high and low area loss patches. However, human activities also created new habitat patches in the landscape and therefore provided opportunities for calcareous grassland plant species to colonize new habitats. This also provided opportunities to study species colonization abilities in the context of habitat restoration. We analyzed species richness in new patches compared to old patches in order to detect colonization credit. We detected the presence of a colonization credit in new patches when using high loss old patches (area loss>80%, exhibiting an extinction debt) or all old patches as a reference. However, when the reference was low loss old patches alone (area loss<80%, less likely to exhibit an extinction debt), no colonization credit was detected. In addition, species composition was similar between new patches and old patches. These results are encouraging for restoration programs. However, the results indicated that the presence of an extinction debt in reference habitats could lead to inaccurate conclusions in restoration monitoring. Therefore, extinction debt should be considered when choosing reference habitats to evaluate restoration success. [less ▲]

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See detailPlant species extinction debt in a temperate biodiversity hotspot: community, species and functional traits approaches
Piqueray, Julien ULg; Bisteau, Emmanuelle; Cristofoli, Sara et al

in Biological Conservation (2011), 144

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the ... [more ▼]

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in Southeast Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35% of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscape configuration. It is likely the landscape configuration no longer supports the species habitat requirements. We demonstrated that non-clonal species are most threatened, as well as taxa that cannot persist in degraded habitats and form only sparsely distributed populations. We discussed our results in light of other studies in similar habitats, and the overall implications for habitat conservation. [less ▲]

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See detailExtinction debt and colonization credit: When both phenomena are integrated
Piqueray, Julien ULg; Cristofoli, Sara; Bisteau, Emmanuelle et al

Conference (2010)

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. These ecosystems suffered a high fragmentation process during the last century. Fragmentation can lead to the ... [more ▼]

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. These ecosystems suffered a high fragmentation process during the last century. Fragmentation can lead to the creation of an extinction debt in remaining habitat patches. In our study site, it was shown in a previous study that Fragmented habitat patches (area loss since 1965 >80%) exhibited an extinction debt in comparison to Stable habitat patches (area loss since 1965 <80%). However, human activities also created new habitat patches in the landscape and provided therefore opportunities for calcareous grassland plant species to colonize new sites. They also provide opportunities for studying species colonization abilities in the context of habitat restoration. We analyzed species richness in these new patches in comparison to old patches in order to detect colonization credit. When taking as reference Fragmented patches (that exhibit an extinction debt) or all old patches (Fragmented and Stable), we concluded to the occurrence of a colonization credit in New patches. However, when the reference is Stable patches (the less likely to exhibit an extinction debt) alone, no colonization credit could be detected. Moreover, correspondence analysis revealed that New patches were similar to old patches in term of species composition. These results are encouraging for restoration programs. They also showed that the presence of an extinction debt in reference habitats can lead to mistaken conclusion in restoration monitoring. Extinction debt occurrence should be taken into account in the choice of reference habitats for evaluation of restoration success. [less ▲]

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See detailHistorical landscape structure affects plant species richness in wet heathlands with complex landscape dynamics
Cristofoli, Sara; Monty, Arnaud ULg; Mahy, Grégory ULg

in Landscape & Urban Planning (2010), 98

The spatio-temporal dynamics of wet heathlands from two landscapes in high Ardenne (Belgium), as well as the consequences of such dynamics on plant communities were investigated. Past and present ... [more ▼]

The spatio-temporal dynamics of wet heathlands from two landscapes in high Ardenne (Belgium), as well as the consequences of such dynamics on plant communities were investigated. Past and present destruction and origin of habitat patches have resulted in a complex network of different aged habitat patches. Current specialist and generalist species richness were assessed in 59 patches and analyzed with respect to present and past patch spatial metrics (controlled for habitat quality). Current patch area affected specialist species richness and current patch connectivity influenced both specialist and generalist species richness. Thirteen of the 59 patches were historical patches, i.e. patches that have remained since the 1770s. In these historical patches, including past landscape structure in the analysis explained more of the variability in current species richness than the current landscape structure alone, suggesting the existence of an extinction debt. [less ▲]

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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)

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See detailDette d'extinction dans un hotspot de biodiversité: approches communauté et espèces
Piqueray, Julien ULg; Bisteau, Emmanuelle; Cristofoli, Sara et al

Conference (2009)

Detailed reference viewed: 56 (5 ULg)