Widespread plant species: natives versus aliens in our changing world

Abstract

Estimates of the level of invasion for a region are traditionally based on relative numbers of native and alien species. However, alien species differ dramatically in the size of their invasive ranges. Here we present the first study to quantify the level of invasion for several regions of the world in terms of the most widely distributed plant species (natives vs. aliens). Aliens accounted for 51.3% of the 120 most widely distributed plant species in North America, 43.3% in New South Wales (Australia), 34.2% in Chile, 29.7% in Argentina, and 22.5% in the Republic of South Africa. However, Europe had only 1% of alien species among the most widespread species of the flora. Across regions, alien species relative to native species were either as well-distributed (10 comparisons) or more widely distributed (5 comparisons). These striking patterns highlight the profound contribution that widespread invasive alien plants make to floristic dominance patterns across different regions. Many of the most widespread species are alien plants, and, in particular, Europe and Asia appear as major contributors to the homogenization of the floras in the Americas. We recommend that spatial extent of invasion should be explicitly incorporated in assessments of invasibility, globalization, and risk assessments

Quantifying the invasiveness of species

“…2, y-axis < 0; G = 112.3, 1 d. f., P < 0.001). This includes recent invaders that are still spreading, but also is consistent with the generally accepted view that only a minority of introduced species are able to establish and spread widely (Williamson and Fitter 1996;Jeschke and Strayer 2005;Ricciardi and Kipp 2008;Stohlgren et al 2011;Hulme 2012). The majority of introduced species may simply be intrinsically weak invaders, or extrinsic environmental factors such as biotic resistance, genetic bottlenecks or simply time since introduction could prevent them from becoming invasive.…”

“…To demonstrate the value of the inter-and intra-specific comparisons described above, we analysed occurrence data that has previously been published (Stohlgren et al 2011). These data are simply the occupancy rates of individual plant species in 10 × 10 km cells in Great Britain (Preston et al 2002), 11 × 12 km cells in the Czech Republic (from the CzechFlor database), 0.25-degree cells in the Republic of South Africa (Henderson 1998;Germishuizen and Meyer 2003), across 23 countries in Europe (Winter et al 2008;DAISIE 2009), and 24 bioregional sub-regions in Argentina (Zuloaga and Morrone 1996).…”

“…However, the vast majority of species that are introduced remain rare, with only a fraction becoming widespread and dominating local communities (Williamson and Fitter 1996;Jeschke and Strayer 2005;Ricciardi and Kipp 2008;Stohlgren et al 2011;Hulme 2012). Identifying the ecological and evolutionary factors that determine these disparate outcomes is the focus of a large body of published empirical work (van Kleunen et al 2010a) including a growing number of hypotheses and synthetic frameworks (Catford et al 2009;Blackburn et al 2011;Gurevitch et al 2011;Jeschke et al 2012).…”

The Human Release Hypothesis for biological invasions: human activity as a determinant of the abundance of invasive plant species

“…Presumably, this reflects that biological invasions are aided by human transport and that species establishment is facilitated by human disturbance 7 . Nevertheless, at the global scale, the proportion of widely distributed alien plant species (relative to all species) is far lower in Europe than in North America – despite Europe’s long history of trade and therefore a longer residence time of alien plants 8 . The observation that Europe serves as a global contributor of alien plant species, whereas North America seems to be a better recipient, has sparked the concept of biological resistance, which explains invasion success or failure in relation to the traits of the native flora 9 .…”

East Asian Species in Alien Flora of European Russia

“…Global species exchange supposed human me diated immigration of species from various continents by different pathways (Mack 2003, Carlton & Ruiz 2005, Hul me et al 2008) resulting the biotic homogenization across the globe as one of the consequences (Olden & Poff 2003, Qian & Ricklefs 2006, Stohlgren et al 2011. All parts of the world except Antarctic proved to be providers of aliens, but America, Asia and Europe have served as important do nor areas of alien species to various regions (Prinzing et al 2002, Fridley 2008, Lambdon et al 2008, Morozova et al 2008, Phillips et al 2010, Jiang et al 2011.…”