The most complete global overview of invasive species in natural areas
2004; Wiley; Volume: 10; Issue: 5-6 Linguagem: Inglês
10.1111/j.1366-9516.2004.00128.x
ISSN1472-4642
Autores Tópico(s)Biological Control of Invasive Species
ResumoDiversity and DistributionsVolume 10, Issue 5-6 p. 505-506 Open Access The most complete global overview of invasive species in natural areas Petr Pyšek, Petr Pyšek Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Pruhonice, Czech RepublicSearch for more papers by this author Petr Pyšek, Petr Pyšek Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Pruhonice, Czech RepublicSearch for more papers by this author First published: 06 September 2004 https://doi.org/10.1111/j.1366-9516.2004.00128.xCitations: 9AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Weber, E. ( 2003 ) Invasive plant species of the world. A reference guide to environmental weeds . CABI Publishing, Wallingford , vii + 548 pp , glossary. Hard cover: Price 75.00 GBP. ISBN 0-85199-695-7 . Every time I met Ewald Weber over the last few years, he said he was working on 'the book'. Only when I saw it published could I understand why it took so long — the amount of information he has synthesized is breathtaking. The book is, by far, the most complete overview of invasive plant species globally and, even better, the information is amazingly well organized. The introduction is pragmatically brief, outlining basic principles of the invasion biology of plants, commenting on practical aspects such as impact and control strategies, and explaining the scope of the book and its organization. Useful references to important web sites and important general papers are not missing either. In some cases, Weber's approach to terminology differs from mine (e.g. that a plant can become invasive within its native range), but this is a relatively minor issue. The core of the book comprises species accounts in alphabetical order, each given a single page with most important synonyms, information on life form, commercial use (i.e. planting purpose), invaded habitats, brief description and succinct paragraph on ecology in both native and introduced geographical range, and reference numbers that relate to a list at the end of the book. Last, but not least, is information on the geographical distribution of species. The way the information is organized here is simply superb. The world is divided into nine regions (Fig. 1), each divided into subregions (32 in total); most of them are within political boundaries, hence clearly circumscribed. This approach made it possible to delimit each species' distribution in each subregion as to whether it is native, naturalized outside natural areas (termed 'introduced'), or invasive in natural areas. Figure 1Open in figure viewerPowerPoint Proportion of species in the total pool of naturalized alien species (= numbers on top of bars) that are recorded as invading natural and seminatural areas. Islands are indicated by hatched bars. An important issue that needs comment is the species coverage, since the terminology differs from that recently suggested in the literature (Richardson et al., 2000; Pyšek et al., 2004). First, Weber follows the definition of the World Conservation Union (IUCN) in considering invasive species as only those that become '… established in natural or seminatural ecosystems or habitats, is an agent of change, and threatens native biological diversity' (McNeely, 2001). Invasive species in agroecosystems are explicitly excluded. Translated to the above mentioned terminology, this is an overview of invasive plant species in natural habitats. This must be borne in mind when interpreting what the data in the book tell us. Secondly, it appears that despite the author repeatedly stating that the species included represent a sample, and Hal Mooney in the introductory note pointing out that Ewald no doubt struggled over which species to include, the overview seems pretty complete to me. Although some important invaders of natural areas are not covered (e.g., Ageratum conyzoides, Agrostis avenacea, Duranta repens, Melinis repens, Opuntia vulgaris, Pseudotsuga menziesii, Senna siamea, S. spectabilis, Spartium junceum, Tridax procumbens) and the mistake that Cronk & Fuller (2001) made by including Swietenia macrophylla is repeated (see Rejmánek, 2002), the sample of species in Weber's book is highly representative. To my mind, the 448 species that are invasive in natural areas in at least one region in the world (this holds for 190 of them, indicating that the screening was very careful indeed) provide a solid insight into the structure of the current pool of invasive plants. It is definitely much better than its predecessor, the overview by Cronk & Fuller (2001), which was much more selective in species coverage (see Rejmánek, 2002). In addition, for included species, the treatment is complete — the account on geographical distribution not only tells you where it is invasive but also lists the regions where it is what Weber calls 'introduced', meaning 'not invasive in natural areas, or solely a weed of agroecosystems, or status as being invasive or not is unknown'. This more or less corresponds to naturalized (sensuRichardson et al., 2000; Pyšek et al., 2004). Having this information on the status of species makes it possible to calculate proportions of naturalized species that became invasive in natural areas. Such a calculation is justified by the fact that most of the latter species have gone through a stage of invading disturbed habitats. It is difficult to resist making some summary statistics and simple analyses with such a data set on your desk. As mentioned previously, I consider the sample of species presented in the book to be representative, so I will not worry for now whether there should have been more or less than the 448 species listed here. Considering life forms, 24.4% of species included are shrubs, 19.2% trees, 16.7% perennial herbs and 10.7% perennial grasses. That almost half of the taxa are woody plants reflects how dangerous this group of plants is in terms of plant invasions. Only 19.2% of the species have no (obvious) commercial use, and may be therefore assumed to have been introduced unintentionally. Of the others, those introduced for ornamental purposes (57.2%) and for erosion control and soil improvement (13.2%) prevail. Not surprisingly, notoriously invasive genera (Acacia nine species, Pinus eight, Solanum seven, Rubus six) and families (Poaceae 74, Fabaceae 49, Asteraceae 20) are most represented. More interestingly, the data reveal that widely naturalized species are not the same as those that are most frequently invasive in natural areas. The set of species occurring in the greatest number of regions according to the former criterion (Datura stramonium 23, Bidens pilosa 20, Chenopodium album 20, Xanthium strumarium 19, Paspalum distichum 17) is completely different from what we get if the latter measure is applied (Lantana camara 12, Leucaena leucocephala 11, Ulex europaeus 9, Fallopia japonica 8, Ailanthus altissima 7, Psidium cattleianum 7, Eichnornia crassipes 7, Hedychium gardnerianum 7, Carpobrotus edulis 7, n = 32). Does the latter list remind you the top 10 of world's invaders? The detailed geographical coverage provides an insight into the global distribution of species invading in natural areas (Fig. 1). By introducing the proportion of all aliens that are classified as invasive in particular regions, it appears that Pacific islands do not harbour a very high number of species but a large proportion of them are invasive. The situation is even worse for Australasia and North America — so many species and almost 60% are invasive in natural areas. At the other end of the spectrum, managers in Asia, South America and Atlantic Islands will be happy to hear that the ratio is low, and only up to 20 species are recorded as invasive (compared to 198 and 174 in Australasia and North America, respectively). The book ends with a list of synonyms. If you do not find your species in alphabetical order, the list tells you under which name it is included, and from now on, if you are not sure where a species invades, it will not be necessary to search in primary sources — now you have Weber's book. The price is hefty (75 Pounds), but to my mind it is worth the investment — this is the book that needs to be on your shelf. Hal Mooney called it 'a monumental effort' and I cannot but agree. He also termed it 'an early warning'. Pretty insistent warning, given the extent of invasion of natural areas worldwide documented in this book. Let's hope it's early enough! REFERENCES Cronk, Q.C.B. & Fuller, J.L. (2001) Plant invaders: the threat to natural ecosystems, 2nd edn. Earthscan Publishing, London. Google Scholar McNeely, J.A. (2001) The great reshuffling: human dimensions of invasive alien species. IUCN, Gland. Google Scholar Pyšek, P., Richardson, D.M., Rejmánek, M., Webster, G., Williamson, M. & Kirschner, J. (2004) Alien plants in checklists and floras: towards better communication between taxonomists and ecologists. Taxon, 53, 131– 143. Wiley Online LibraryWeb of Science®Google Scholar Rejmánek, M. (2002) Plant invaders: the threat to natural ecosystems by Quentin C.B. Cronk and Janice L. Fuller. Environmental Conservation, 29, 266– 267. Google Scholar Richardson, D.M., Pyšek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C.J. (2000) Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions, 6, 93– 107. Wiley Online LibraryWeb of Science®Google Scholar Citing Literature Volume10, Issue5-6September 2004Pages 505-506 FiguresReferencesRelatedInformation
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