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The effects of alien invasive species on biodiversity have been described as “immense, insidious and usually irreversible” (IUCN 2000). There is no doubt that invasive species can cause severe economic and ecological damage (Mack et al. 2000). They may soon surpass habitat loss as the main cause of ecological disintegration globally (Vitousek et al. 1997, Chapin et al. 2000) and are probably already the main cause of extinctions in island ecosystems. The breaching of biogeographic boundaries by the widespread, recent human transport of species has caused rapid and radical change in biological communities, including multiple extinctions. To minimise further extinctions and other ecological changes, the most important priority is to reduce the risks of new invasions. After prevention, the next priority is to eradicate existing invasive species, where this is possible. These aims are embodied in the United Nations Convention on Biological Diversity, which states that parties to this convention should “ prevent the introduction of, control or eradicate, those alien species which threaten ecosystems, habitats or species”.

Eradication of Island invasives: practical actions and result achieved at the University of Auckland, 19-23 February, 2001

In September 2003, Hurricane Isabel caused unexpectedly high levels of wind damage to an 80-to 100-year-old forest in the Piedmont of Maryland. The storm had decreased in intensity from landfall by the time it reached the study site—sustained winds were moderate and maximum gusts recorded in the area were only 62.7 mph (28.1 m?s-1). Midsized gaps (up to 1 ha) were created in forest that historically had only small or single-tree gaps. Isabel created the opportunity to determine whether natural disturbance facilitates the spread of exotic invasive plant species. Exotic invasive species populations were sampled in 400 5 x 5 m quadrats in a heavily damaged 1-ha, long-term forest study plot and in 160 5 x 5 m quadrats in 0.4 ha of a nearby, less-damaged forest between mid-October and mid-December 2003. Light levels (quantum flux density of photosynthetically active radiation) in the heavily disturbed Permanent Plot and the Less Damaged control plot were surveyed in October 2003 and 2004. The fall 2004 resurvey for exotic plants has also been completed. Based on a random sample of the fall 2004 exotics data, exotic invasive plant species responded strongly to the increased light levels in patches of forest damaged by Isabel. Collectively, the mean increase in percentage cover of exotic plants was 47.8% in high-light canopy gaps versus only 4.8 % in low-light non-gaps and 4.2% in the less-damaged forest. Several individual exotic species—Polygonum perfoliatum, Polygonum positive responses to higher light levels. The shadeloving caespitosum, and Lonicera japonica had significant biennial, Alliaria petiolata, changed significantly in the opposite direction, decreasing in the high-light areas and increasing in the lowlight areas. The authors are also investigating the interaction of exotic plants with native plants, forest regeneration, and white-tailed deer (Odocoileus virginianus) in damaged areas. Study areas and exclosures for these projects were set up in 2004 and will be resurveyed beginning in 2005.

Le Centre assure l’élaboration de méthodes, le développement de formations, la capitalisation des connaissances et la diffusion de savoir-faire et de bonnes pratiques. Il consacre ainsi son activité à toutes les EEE de faune et de flore, en milieux terrestres, marins et d’eau douce, en métropole comme en outre-mer.

Website for invasive species for France

especes exotiques envahissantes.france uicn guide

Des invasions biologiques aux conséquences multiples: Les espèces exotiques envahissantes (EEE dans la suite de l‘ouvrage) constituent l’une des principales pressions sur la biodiversité à l’échelle mondiale, au même titre que la destruction des habitats naturels, la surexploitation des ressources, les pollutions ou le changement climatique. Les espèces introduites, lorsqu’elles se révèlent envahis¬santes, provoquent des impacts multiples, directs ou indi¬rects, affectant les espèces indigènes, les habitats naturels et les services rendus par les écosystèmes, mais égale¬ment les activités économiques et la santé humaine. Partout dans le monde, à des échelles géographiques et des intensités très variables, les EEE provoquent des altérations du fonctionnement des écosystèmes et causent la régres¬sion d’espèces indigènes. Selon les dernières estimations de la Liste rouge des espèces menacées de l’UICN, elles constituent une menace pour près d’un tiers des espèces terrestres menacées de disparition et sont impliquées dans la moitié des extinctions connues (UICN France, 2015). Sur le plan économique, les conséquences négatives des invasions biologiques peuvent être très importantes (Ket¬tunen et al., 2009). Les impacts qui génèrent des coûts économiques pour divers acteurs ou la société d’une manière générale sont multiples : dépréciation des rende¬ments agricoles, coûts sanitaires, coûts de régulation des invasions de ces espèces sur le terrain, coûts de restaura¬tion des milieux naturels envahis et, de manière plus diffi¬cilement quantifiable, les impacts sur les services rendus par les écosystèmes. Sur le plan sanitaire, de nombreuses espèces introduites constituent de plus une menace pour la faune et la flore ou pour la santé humaine. Elles peuvent être allergènes, pa¬thogènes ou toxiques, ou encore constituer des réservoirs ou des vecteurs de micro-organismes et virus pathogènes.

Retrouvez le site de l’initiative largement mis à jour et notamment une description des enjeux et de l’initiative, les actualités, bases de données et ressources. Vous y trouverez également une page et la base de données spécifiques à la Nouvelle-Calédonie.

Suite à la soutenance de thèse effectuée en juillet 2018 à l’Université de Massey, le manuscrit de Martin Thibault, intitulé « Le bulbul à ventre rouge (Pycnonotus cafer): dynamique d’invasion et impacts écologiques d’un oiseau introduit en Nouvelle Calédonie. Invasive alien species are a major cause of biodiversity loss globally, especially on islands where high species richness and levels of endemism accentuate their impacts. Various international institutions have constructed lists of the most harmful invasive species to help environment managers at both global and local scales to prioritize their efforts. The red-vented bulbul (Pycnonotus cafer) is a passerine bird species considered among the three worst invasive birds on the planet. This species is currently spreading over the tropical archipelago of New Caledonia, one of the 36 world biodiversity hotspots. This dissertation presents the findings of a PhD study conducted in New Caledonia with two objectives: 1) to describe this introduced population, and 2) to evaluate the threats from its dispersal using both existing knowledge and new in-situ and ex-situ data and a variety of analysis techniques. From the literature, I identified three key impacts explaining the species’ status: i) damage to agricultural crops, ii) noxious seed dispersal, and iii) competition with other avifauna. I estimated the local population size (approx. 140,000 individuals), its habitat use (inhabited areas), its density along an urbanization gradient (30-120 ind/km2), and I produced lists of consumed plant and animal species and identified a colour preference in the foraging strategy of the red-vented bulbul. Exploration of each impact category revealed i) substantial losses on fruit production (18% of tomato production), ii) impact on the abundance of nine native bird species that may be driving a spatial reassembly of the community, and iii) a short distance dispersal (77-92 m) that could promote the dispersal of introduced plant species at the expense of endemic species. Finally, through modelling, I estimated the climatic niche of the species at a global scale and identified that most island territories as suitable for the establishment of this invasive bird species. Regardless of whether the red-vented bulbul deserves its status as “world worst” species, quantitative impact assessments in its alien range such as the studies presented here are needed to prevent the dispersal and harmful impacts of this species on human activities and sensitive ecosystems. Implications for management are discussed.

In tropical forests, natural disturbance creates opportunities for species to claim previously utilized space and resources and is considered an important mechanism in the maintenance of species diversity. However, ecologists have long recognized that disturbance also promotes exotic plant invasions. Cyclones cause extensive defoliation, loss of major branches and multiple tree falls, resulting in a significantly more open canopy and increased light and heat levels in the understorey. The widespread and massive disturbance caused by cyclones provides ideal conditions for rapid recruitment and spread of invasive species. The ecological roles of invasive species in rainforest habitats following such a severe disturbance are poorly understood. Severe category 4 Cyclone Larry crossed the North Queensland coast in March 2006 causing massive disturbance to rainforest habitats from Tully to Cairns and west to the Atherton Tablelands. We established 10 plots in an area extensively damaged by this cyclone near El Arish in North Queensland. On each plot nine 2×2 m quadrats were established with three quadrats per plot in each of the following treatments: (i) complete debris removal down to the soil layer, (ii) removal of coarse woody debris only, and (iii) uncleared. We monitored recruitment, growth and mortality of all native and invasive species in the 90 quadrats every 3 months since the cyclone. Here we present the recruitment dynamics of invasive species across the study area in relation to the level of disturbance, the type of quadrat treatment, and the diversity and abundance of the native recruiting flora over the first 12 months post?cyclone. Our results suggest that invasive species will mostly comprise a transient component of the flora in the early stages of the successional response. However, some species may have longer?term effects on the successional trajectory of the rainforest and future forest composition and structure.