Search results for "Species richnes"
showing 10 items of 427 documents
Species immigration, extinction and turnover of vascular plants in boreal lakes
1999
Dictated by limited resource availability for land acquisition, a central question in conservation biology is the ability of areas of different size to maintain species diversity. The selected reserves should not only be species rich at the moment, but should also maintain species diversity in the long run. We used two sets of data on vascular plant species in boreal lakes collected in 1933/34 and 1996 to test the relationships between lake area and the extinction, immigration and turnover rates of the species. Moreover, we investigated, whether the number of species in 1933/34 or water connection between lakes was related to extinction, immigration and turnover rates of species. We found t…
Conservation of vascular plants in single large and several small mires: species richness, rarity and taxonomic diversity
1998
1. This study on vascular plant species of boreal spruce and pine mires concentrated on two geometrical principles: whether single large or several small (SLOSS) reserves contain more species and whether patch shape should be as nearly circular as possible. 2. SLOSS and patch shape have usually been tested by using species richness. Only a few studies have taken the rarity of species into account, and taxonomic diversity has never been used. In our study, all three of these factors were used. 3. Our results showed that the number of species was not related to the spruce mire size, but it increased in relation to the pine mire size. In contrast, the rarity score increased in relation to the …
Benchmarking plant diversity of Palaearctic grasslands and other open habitats
2021
© 2021 The Authors.
Summer phytoplankton assemblages across trophic gradients in hard-water reservoirs
1998
Summer phytoplankton assemblages are described and characterised according to their prevalence in a series of hard-water reservoirs of eastern Spain that had been classified in trophic categories on OECD criteria. Distribution patterns of phytoplankton species were ordinated statistically by principal components analysis (PCA). The first component was strongly related to trophic gradient and it particularly discriminated the eutrophic and hypertrophic reservoirs. The second component segregated life-forms, so that (1), on the oligo-mesotrophic side, large dinoflagellates were separated from small centric diatoms, unicellular chrysophytes and filamentous ullotrichales and, on the eu-hypertro…
Fossil echinoid (Echinoidea, Echinodermata) diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France).
2013
11 pages; International audience; This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century. This dataset compiles occurrence data (referenced by locality names and geographic coordinates with decimal numbers) of fossil echinoids both collated from the literature published over a century and a half, and completed by data from …
Extrapolation des inventaires de biodiversité incomplets : comment estimer au mieux le nombre d’espèces manquantes et prévoir l’effort additionnel d’…
2016
While approaching or even reaching total completeness remains the idealgoal of any species inventory, incomplete samplings are deemed to become more often the rule, that are significantly more difficult to cope with (such as (micro-) invertebrates, for example).However, once post-operated appropriately, incomplete samplings may provide farmore data than it would seem and it is indeed possible to obtain valuable extra information froma reliable mode of extrapolation of the so-called Species Accumulation Curve.In fact, numerous tools designed for the exploitation of incomplete samplings havealready been proposed in the literature but the concern, with these numerous different tools, isprecise…
Groundwater biodiversity in Europe. In: Freshwater Biology Special Issue, Assessing and Conserving Groundwater Biodiversity (Eds. J. Gibert & D.C. Cu…
2009
International audience
Variations spatiales et temporelles de communautés adventices des cultures annuelles en France
2010
Résumé de thèse; National audience
Loss in microbial diversity affects nitrogen cycling in soil
2013
International audience; Microbial communities have a central role in ecosystem processes by driving the Earth's biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 s…
Gestion territoriale des adventices : effets des propriétés du paysage sur les communautés adventices et sur leur régulation par les carabidae
2015
Landscape-scale management is known to affect pest and biodiversity levels in agroecosystems. Here, we focus on the lanscape drivers of arable weeds, first by reviewing evidence of direct landscape effects on weed species richness and abundance and then by analyzing current knowledge on landscape effects on carabids, which are well-known weed seed predators that contribute to the biological regulation of weeds. Our analysis shows that (i) heterogeneous landscapes usually harbor higher species richness and more diversified communities than simple ones, (ii) total weed and carabid abundances appear seldomly affected by the landscape context of arable fields and (iii) weed seed predation in fi…