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Auteur Johan Van Valkenburg |
Documents disponibles écrits par cet auteur (7)
trié(s) par (Pertinence décroissant(e), Titre croissant(e)) Affiner la rechercheNaturalised Hakea. What species are we actually talking about in Europe ? / Johan Van Valkenburg in Botany letters, vol. 171, n°3 (Année 2024)
Titre : Naturalised Hakea. What species are we actually talking about in Europe ? Auteurs : Johan Van Valkenburg, Auteur ; J. Beyer, Auteur ; P. Champion, Auteur ; Julie Coetzee, Auteur ; Katia Diadema, Auteur ; S. Kritzinger-Klopper, Auteur ; E. Marchante, Auteur ; L. Piet, Auteur ; David M. Richardson, Auteur ; Ines Schönberger, Auteur Article en page(s) : pp. 357-370 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Hakea
[Thèmes] Flore vasculaire (phanérogames et cryptogames vasculaires)Mots-clés : espèce exotique envahissante Résumé : "Hakea sericea Schrad. & J.C.Wendl. (Proteaceae) is a shrub or small tree native to south-eastern Australia. The species has been introduced to other countries; it has naturalised and become invasive in France, New Zealand, Portugal, and South Africa. During the review process of the Pest Risk Analysis for the European and Mediterranean Plant Protection Organization (EPPO) on Hakea sericea in 2017, the actual identity of the plant causing major negative biodiversity impact in Portugal was questioned. Flowering material from Portugal and additional collections from South Africa and New Zealand were collected in order to clarify the taxonomical status. To make the survey on the proper identity of the Hakea plants invasive in Portugal more concise, all Hakea species encountered in Portugal, France, South Africa and New Zealand were included. For morphological distinction of the species the length of the pistil and fruit characters were used. For molecular analysis Illumina sequencing in combination with de novo assembly and extraction of loci was used. Results show that invasive populations of Hakea in Portugal belong to H. decurrens R.Br a species that, although very similar and sometimes considered synonymous with H. sericea, can be distinguished both morphologically and on the basis of cpDNA. Both species occur in France and in New Zealand, while only H. sericea occurs in South Africa. Both species are invasive and seem to have similar impacts on biodiversity in invaded ranges. The morphologically similar species H. gibbosa (J.White) Cav. occurs in both New Zealand and South Africa. By adopting the H. sericea sensu lato concept for inclusion of the species on the List of Union Concern pursuant of Regulation (EU) No 1143/2014, a potential legislative controversy can be prevented." (source : auteurs) Type de publication : périodique Référence biblio : Van Valkenburg J., Beyer J., Champion P., Coetzee J., Diadema K., Kritzinger-Klopper S., Marchante E., Piet L., Richardson D., Schönberger I., 2024 - Naturalised Hakea. What species are we actually talking about in Europe ? Botany letters, 171 (3) : 357-370. ID PMB : 72723 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=72723
in Botany letters > vol. 171, n°3 (Année 2024) . - pp. 357-370[article]Exemplaires(1)
Cote Localisation Disponibilité P0177-6 Brest Disponible
Titre : Monographs on invasive plants in Europe: Ageratina adenophora (Spreng.) R. M. King & H. Rob Auteurs : Guillaume Fried, Auteur ; Arunava Datta, Auteur ; Giuseppe Brundu, Auteur ; Daniel Chapman, Auteur ; Swen Follak, Auteur ; Danièle Frohlich, Auteur ; David M. Richardson, Auteur ; Johan Van Valkenburg, Auteur ; Rob Tanner, Auteur Article en page(s) : pp. 414-439 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Ageratina adenophora (Spreng.) R.M.King & H.Rob.
[ZG] EuropeMots-clés : espèce végétale invasive Résumé : "Ageratina adenophora (Spreng.) R.M. King & H. Rob. (Crofton wéed) is a triploid, apomictic perennial herb or sub-shrub native to Mexico that is highly invasive in many parts of. the world. This species thrives in diverse habitats, from wet forest margins to dry slopes and disturbed urban areas. Initially introduced globally as an ornamental plant, it has now naturalized across many continents, including Europe, Asia, Africa, Oceania, and the Americas, often displacing native flora and altering ecosystems. Its introduction to Europe dates back to the 19th century, with naturalization first recorded on the French Riviera. Ageratina adenophora is now established in several southern European countries (Portugal, Spain, France, Italy, Croatia, Greece) and across the Macaronesian islands. It spreads via wind- and water-dispersed seeds and can also propagate vegetatively, particularly along riparian systems and disturbed sites. Despite its prolific reproduction and adaptability, its expansion in Europe has so far remained moderate, possibly due to climatic limitations and unsuitable habitats. Ecologically, A. adenophora exhibits remarkable phenotypic plasticity and physiological adaptations that enable it to survive a range of abiotic stresses including cold, drought, and variable light levels. The species benefits from mutualisms with soil microbes and displays enhanced nitrogen-use efficiency in introduced ranges. Although initially valued for ornamental and medicinal purposes, A. adenophora is now widely recognized as a harmful invader. It invades both natural and semi-natural habitats and has demonstrated a capacity to alter soil chemistry, suppress native vegetation through competition and allelopathy, and host diverse pathogens and endophytes. Ageratina adenophora negatively impacts biodiversity, ecosystem functioning, and agriculture by forming dense, monospecific stands and disrupting native communities. Its presence in biodiversity hotspots and protected areas—such as Himalaya, South Africa, and the Canary Islands—poses significant conservation challenges. Control efforts, including the use of biological agents such as Procecidochares utifis Stone 1947, have yielded mixed results. The most effective method for small areas is to physically remove A. adenophora before it sets seed. This can be done by hand-pulling or cutting. Given the continued spread and resilience of this species there is an urgent need for coordinated management strategies and increased awareness, especially in the face of climate change which may further facilitate its expansion in Europe and beyond." (source : auteurs) Type de publication : périodique Référence biblio : Fried G., Datta A., Brundu G., Chapman D., Follak S., Frohlich D., Richardson D., Van Valkenburg J., Tanner R., 2025 - Monographs on invasive plants in Europe: Ageratina adenophora (Spreng.) R. M. King & H. Rob. Botany letters, 172 (4) : 414-439. ID PMB : 73356 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=73356
in Botany letters > vol. 172, n°4 (Année 2025) . - pp. 414-439[article]Exemplaires(1)
Cote Localisation Disponibilité P0177-6 Brest Disponible Landoltia punctata (G. Mey.) D.H. Les & D.J. Crawford (dotted duckweed), a new record for The Netherlands / Johan Van Valkenburg in Gorteria, vol. 33 (Années 2007-2008)
Titre : Landoltia punctata (G. Mey.) D.H. Les & D.J. Crawford (dotted duckweed), a new record for The Netherlands Type de document : texte imprimé Auteurs : Johan Van Valkenburg, Auteur ; Roelf Pot, Auteur Année de publication : 2008 Article en page(s) : pp. 41-49 Langues : Néerlandais (nla) Catégories : [ZG] Pays-Bas Mots-clés : Landoltia punctata illustration description Résumé : "Landoltia punctata, native to Australia and SE Asia, was first recorded in The Netherlands in 2007. The species can be recognized by the narrowly egg-shaped to slightly kidney-shaped fronds, with one or three curved nerves. The ventral side if often purplish-red, especially at the margin. The fronds have more than one, but always relatively few roots. The species was often encountered as contamination in water tanks at garden centres and pet shops selling aquarium plants. It is very plausible that Landoltia punctata has been introduced as a contamination with aquarium plants from South-East Asia. In Europe the number of recent records is low and some were only temporary. It is not very likely that the species will be a nuisance to water management in The Netherlands. Its ecology hardly differs from other indigenous duckweed species and the risk of replacement of a native species is very low." (source : auteurs) Type de publication : périodique Référence biblio : van Valkenburg J., Pot R., 2008 - Landoltia punctata (G. Mey.) D.H. Les & D.J. Crawford (dotted duckweed), a new record for The Netherlands. Gorteria, 33 : 41-49. ID PMB : 69812 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=69812
in Gorteria > vol. 33 (Années 2007-2008) . - pp. 41-49[article]Exemplaires(0)
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Titre : Monographs on invasive plants in Europe N° 5 : Ambrosia trifida L. Type de document : texte imprimé Auteurs : Bruno Chauvel, Auteur ; Guillaume Fried, Auteur ; Swen Follak, Auteur ; Daniel Chapman, Auteur ; Yuliana Kulakova, Auteur ; Thomas Le Bourgeois, Auteur ; Dragana Marisavljevic, Auteur ; Arnaud Monty, Auteur ; Jean-Pierre Rossi, Auteur ; Uwe Starfinger, Auteur ; Rob Tanner, Auteur ; Xavier Tassus, Auteur ; Johan Van Valkenburg, Auteur ; Emilie Regnier, Auteur Année de publication : 2021 Article en page(s) : pp. 167-190 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Ambrosia trifida L.
[ZG] EuropeMots-clés : plante invasive Résumé : "Ambrosia trifida L. (giant ragweed, Asteraceae) is native to the North American continent and was introduced into Europe and Asia at the end of the 19th century. In its native range, this tall annual species is common in riparian and ruderal habitats and is also a major weed in annual cropping systems. For nearly a century, A. trifida has also been of great concern in the U.5. for its highly allergenic pollen, necessitating targeted control measures to reduce its impact on human populations.
Based on the distribution of A. trifida in North America and in its introduced range, riparian systems in the rest of the world may be particularly at risk to invasion, with potential negative consequences for their biodiversity. Currently, A. trifida has invaded Asia more widely than Europe, Iikely due to the more favourable local conditions in Asia. Throughout its introduced range, A. trifida is host to a Iimited number of invertebrates and pathogens and only a few biological agents are available for its control. The main impacts of A. trifida at a globallevel are on crop yield and human health, resulting in significant socio-economic impacts. The success of A. trifida invasion in areas in which it has been introduced is still undear, but dimate change may increase dimate suitability, increasing the potential for A. trifida to spread. While effective management in cultivated fields seems potentially possible, the development and control of A. trifida in natural riparian habitats is of great concern due to the difficulty of management in these areas." (source : auteurs)Type de publication : périodique Référence biblio : Chauvel B., Fried G., Follak S., Chapman D., Kulakova Y., Le Bourgeois T., Marisavljevic D., Monty A., Rossi J.-P., Starfinger U., Tanner R., Tassus X., van Valkenburg J., Regnier E., 2022 - Monographs on invasive plants in Europe N° 5 : Ambrosia trifida L. Botany letters, 169 (2) : 167-190. ID PMB : 70319 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=70319
in Botany letters > vol. 168, n°2 (Année 2021) . - pp. 167-190[article]Exemplaires(1)
Cote Localisation Disponibilité P0177-6 Brest Disponible 
Titre : Myriophyllum rubricaule sp. nov., a M. aquaticum look-alike only known in cultivation Type de document : texte imprimé Auteurs : Johan Van Valkenburg, Auteur ; Leni Duister, Auteur ; Edu Boer, Auteur ; Tom M. Raaymaker, Auteur Année de publication : 2022 Article en page(s) : 15 p. Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Myriophyllum
[Espèces (in biblio)] Myriophyllum aquaticum
[Thèmes] TaxonomieMots-clés : espèce végétale invasive plante horticole Résumé : "A confusingly labeled water-milfoil of obscure status, known only in cultivation, is here formally described as a new species, Myriophyllum rubricaule Valk. & Duist. sp. nov. This species has fully replaced M. aquaticum in the horticultural trade in Europe since the addition of M. aquaticum to the list of invasive alien species of Union concern (EU regulation no. 1143/2014) in 2016. This manuscript provides a morphological description of M. rubricaule sp. nov., and its distinction from M. aquaticum is further supported by molecular data (chloroplast and nuclear loci)." (source : auteurs) Type de publication : périodique Référence biblio : van Valkenburg J., Duister L., Boer E., Raaymaker T., 2022 - Myriophyllum rubricaule sp. nov., a M. aquaticum look-alike only known in cultivation. European Journal of Taxonomy, 2022 : 15 p. ID PMB : 70999 En ligne : https://sciencepress.mnhn.fr/fr/periodiques/european-journal-taxonomy/828/1 Format de la ressource électronique : document Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=70999
in European Journal of Taxonomy > Année 2022 (Année 2022) . - 15 p.[article]Exemplaires(0)
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