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Bezemer T.M.,Netherlands Institute of Ecology | Bezemer T.M.,Wageningen University | Fountain M.T.,East Malling Research | Barea J.M.,CSIC - Experimental Station of El Zaidin | And 17 more authors.
Ecology | Year: 2010

Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and providers of resources to the soil food web, are of vital importance for the composition, structure, and functioning of soil communities. However, whether natural soil food webs that are completely open to immigration and emigration differ underneath individual plants remains unknown. In a biodiversity restoration experiment we first compared the soil nematode communities of 228 individual plants belonging to eight herbaceous species. We included grass, leguminous, and non-leguminous species. Each individual plant grew intermingled with other species, but all plant species had a different nematode community. Moreover, nematode communities were more similar when plant individuals were growing in the same as compared to different plant communities, and these effects were most apparent for the groups of bacterivorous, carnivorous, and omnivorous nematodes. Subsequently, we analyzed the composition, structure, and functioning of the complete soil food webs of 58 individual plants, belonging to two of the plant species, Lotus corniculatus (Fabaceae) and Plantago lanceolata (Plantaginaceae). We isolated and identified more than 150 taxa/groups of soil organisms. The soil community composition and structure of the entire food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon mineralization or food web stability. Hence, the composition and structure of entire soil food webs vary at the scale of individual plants and are strongly influenced by the species identity of the plant. However, the ecosystem functions these food webs provide are determined by the identity of the entire plant community. © 2010 by the Ecological Society of America. Source


Duarte I.M.,Polytechnic Institute of Coimbra | De Almeida M.T.M.,University of Minho | Brown D.J.F.,Central Laboratory of General Ecology | Marques I.,Instituto Gulbenkian Of Ciencia | And 2 more authors.
Nematology | Year: 2010

A survey of virus vector trichodorid nematodes was carried out in the central and northern regions of Portugal. Morphobiometric identification showed the presence of trichodorid species previously reported from Portugal, except for Paratrichodorus porosus, which is reported for the first time in Continental Europe. Small subunit ribosomal DNA (SSU rDNA) sequences of ten different species occurring in Portugal were obtained and a phylogenetic analysis based on their alignment was performed to infer relationships among the different Portuguese trichodorid species and three non-indigenous populations (Nanidorus minor, P. allius and P. teres). The resulting phylogenetic tree is in agreement with the currently accepted classification for Trichodoridae, except for Nanidorus, which clusters together with Trichodorus species, while the genera Paratrichodorus and Trichodorus appear as two distinct groups. A better understanding of the generic groupings in the family Trichodoridae was found. Based on the new molecular analyses we herein accept Nanidorus as a valid genus. © 2010 Brill Academic Publishers. Source


van de Vijver B.,National Botanic Garden of Belgium | Zidarova R.,Central Laboratory of General Ecology | de Haan M.,National Botanic Garden of Belgium
Nova Hedwigia | Year: 2011

During a revision of the genus Luticola on the South Shetland Islands and James Ross Island, four unknown Luticola species were observed. Based on detailed light microscopy and scanning electron microscopy observations, the species are described as new to science: Luticola katkae Van de Vijver & Zidarova sp. nov., Luticola vermeulenii Van de Vijver sp. nov., Luticola adelae Van de Vijver & Zidarova sp. nov. and Luticola raynae Zidarova & Van de Vijver sp. nov. Their morphology and taxonomy is discussed comparing each species with similar Luticola taxa. Notes on their ecology are added. Subsequently, the distribution of all Luticola taxa in the subantarctic and Antarctic regions is investigated resulting in a clear separation of the Subantarctic Region, the Maritime Antarctic Region and the Antarctic Continent. © 2011 J. Cramer in Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany. Source


Terziyski D.,Institute of Fisheries and Aquaculture Plovdiv | Kalchev R.,Bulgarian Academy of Science | Dochin K.,Institute of Fisheries and Aquaculture Plovdiv | Piskov I.,Institute of Fisheries and Aquaculture Plovdiv | And 2 more authors.
Bulgarian Journal of Agricultural Science | Year: 2010

The top-down effect of densities of common carp (Cyprinus carpio L.) and bighead carp (Aristichthys nobilis Rich.) larvae applied in proportions 3:1 and 1:3 on biological fish pond characteristics like plankton primary production, respiration, abundances of bacterio, phyto and zooplankton, chlorophyll etc. was tested. The experiment lasted 4 months (May to September), was repeated in two consecutive years (2007, 2008) included four ponds in year 2007 from two different localities and five ponds in 2008 from one and the same locality. The measured biological variables showed statistically significant differences between means of localities, years and stocking variants. The sources of variations between localities and years have their ground in objective circumstances accompanying the experiment implementation but could not override the top-down effect of fish stocking variants. The variant 1 (3:1 common carp: bighead carp densities) which proved to be more effective was distinguished by higher phytoplankton and lower zooplankton abundances. Its primary production and respiration were also lower than in variant 2 (1:3 densities of common carp: bighead carp). Source


Van De Vijver B.,National Botanic Garden of Belgium | Ector L.,Center De Recherche Public Gabriel Lippmann | De Haan M.,National Botanic Garden of Belgium | Zidarova R.,Central Laboratory of General Ecology
Diatom Research | Year: 2010

The genus Microcostatus was erected in 1998 by Johansen & Sray to accommodate a small number of tiny naviculoid species belonging to the former section Naviculae minusculae, characterized by the presence of the typical microcostae, a series of external transapical costae near the axial area, the possession of a simple raphe system and the lack of a conopeum, typical for the genus Fallacia. During a survey of the Antarctic non-marine diatom flora, two Microcostatus species were found in several localities in the southern Atlantic and Indian Ocean. Comparison with type material and with the sparse literature that exists on the genus Microcostatus, the Antarctic species were identified as Microcostatus naumannii (Hustedt) Lange-Bertalot and M. maceria (Schimanski) Lange-Bertalot. The species showed the typical northern distribution although some older records of M. naumannii were known from the Antarctic Region. The purpose of this study was the morphological characterization of both species using detailed light and scanning electron microscopy observations. Their ecology and worldwide biogeographical distribution was discussed in the view of the debate on the global distribution of microorganisms. Source

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