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Invasive species science has focused heavily on the invasive agent. However, management to protect native species also requires a proactive approach focused on resident communities and the features affecting their vulnerability to invasion impacts. Vulnerability is likely the result of factors acting across spatial scales, from local to regional, and it is the combined effects of these factors that will determine the magnitude of vulnerability. Here, we introduce an analytical framework that quantifies the scale‐dependent impact of biological invasions on native richness from the shape of the native species–area relationship (SAR). We leveraged newly available, biogeographically extensive vegetation data from the U.S. National Ecological Observatory Network to assess plant community vulnerability to invasion impact as a function of factors acting across scales. We analyzed more than 1000 SARs widely distributed across the USA along environmental gradients and under different levels of non‐native plant cover. Decreases in native richness were consistently associated with non‐native species cover, but native richness was compromised only at relatively high levels of non‐native cover. After accounting for variation in baseline ecosystem diversity, net primary productivity, and human modification, ecoregions that were colder and wetter were most vulnerable to losses of native plant species at the local level, while warmer and wetter areas were most susceptible at the landscape level. We also document how the combined effects of cross‐scale factors result in a heterogeneous spatial pattern of vulnerability. This pattern could not be predicted by analyses at any single scale, underscoring the importance of accounting for factors acting across scales. Simultaneously assessing differences in vulnerability between distinct plant communities at local, landscape, and regional scales provided outputs that can be used to inform policy and management aimed at reducing vulnerability to the impact of plant invasions. [ABSTRACT FROM AUTHOR]

Invasive alien species (IAS) are currently considered as one of the major causes of global environmental change. To manage the IAS, it is crucial to identify the different environmental and associated anthropogenic drivers that contribute to invasion of alien species in non-native regions. Although multiple drivers of invasion have been identified at a global scale, the relative roles of these are known to vary considerably at regional scales. Here, we investigate the role of key environmental and anthropogenic drivers in determining the diversity and distribution of selected invasive alien plant species in Kashmir Himalaya. We generated an extensive distribution dataset of these species through field sampling across the region and supplemented it with novel herbarium records. We also extracted data on the relevant environmental (climatic, soil and topographic) and anthropogenic drivers for the study region. The random forest model was employed to quantify the relative contribution of these drivers to determine the two common diversity metrics (species richness and abundance) of selected invasive alien plants. We found that soil water content followed by distance to city, the maximum air temperature, soil pH, soil temperature and human population density exerted the greatest influence on species richness of the invasive plants. Species abundance was significantly influenced by the maximum air temperature followed by soil temperature, distance to city, slope, soil pH and human population density. Overall, our findings help in disentangling the individual and interactive roles of multiple drivers of plant invasions, with wide-ranging implications for management in this Himalayan region and similar landscapes elsewhere. • Invasive alien species are one of major causes of global environmental change. • Environmental and anthropogenic drivers of invasive plants in the Himalaya studied. • Soil water content and distance to city had greatest influence on species richness. • Maximum air temperature had greatest influence on invasive species abundance. • Our study disentangles individual and interactive roles of multiple drivers in plant invasions. [ABSTRACT FROM AUTHOR]

Alien invasive plants pose a threat to global biodiversity and the cost of control continues to rise. Early detection and prediction of potential risk areas are essential to minimize ecological and socio-economic costs. In this study, the Maxent model was used to predict current and future climatic conditions to estimate the potential global distribution of the invasive plant Xanthium italicum. The model consists of 366 occurrence records (10 repeats, 75% for calibration and 25% for verification) and 10 climate prediction variables. According to the model forecast, the distribution of X. italicum was expected to shrink in future climate scenarios with human intervention, which may be mainly caused by the rise in global average annual temperature. The ROC curve showed that the AUC values of the training set and the test set are 0.965 and 0.906, respectively, indicating that the prediction result of this model was excellent. The contribution rates of annual mean temperature, monthly mean diurnal temperature range, standard deviation of temperature seasonal change and annual average precipitation to the geographical distribution of X. italicum were 65.3%, 11.2%, 9.0%, and 7.7%, respectively, and the total contribution rate was 93.2%. These four variables are the dominant environmental factors affecting the potential distribution of X. italicum, and the influence of temperature is greater than that of precipitation. Through our study on the potential distribution prediction of X. italicum under the future climatic conditions, it has contribution for all countries to strengthen its monitoring, prevention and control, including early warning. [ABSTRACT FROM AUTHOR]

Latitudinal patterns of biodiversity have long been a central topic in ecology and evolutionary biology. However, while most previous studies have focused on native species, little effort has been devoted to latitudinal patterns of plant invasions (with a few exceptions based on data from sparse locations). Using the most up‐to‐date worldwide native and alien plant distribution data from 801 regions (including islands), we compared invasion levels (i.e. alien richness/total richness) in the Northern and Southern Hemispheres and across continental regions and islands around the globe. Results from quantile regressions using B‐splines to model nonlinearity showed (1) declining richness with increasing latitude, although the highest alien richness occurs at around 40 degrees in both hemispheres, (2) decreasing invasion levels towards higher latitudes on islands but a unimodal pattern in invasion level in continental regions in each hemisphere, (3) significantly higher invasion levels on islands than in continental regions and (4) a greater variability in invasion levels on islands at low latitudes than on high‐latitude islands. In continental regions, only the mid‐latitudes had high variability with both low and high invasion levels. Our findings identified latitudes with invasion hotspots where management is urgently needed, and latitudes with many areas of low invasions but high conservation potential where prevention of future invasions should be the priority. [ABSTRACT FROM AUTHOR]

Predicting plant distributions under climate change is constrained by our limited understanding of potential rapid adaptive evolution. In an experimental evolution study with the invasive common ragweed (Ambrosia artemisiifolia L.) we subjected replicated populations of the same initial genetic composition to simulated climate warming. Pooled DNA sequencing of parental and offspring populations showed that warming populations experienced greater genetic divergence from their parents, than control populations. In a common environment, offspring from warming populations showed more convergent phenotypes in seven out of nine plant traits, with later flowering and larger biomass, than plants from control populations. For both traits, we also found a significantly higher ratio of phenotypic to genetic differentiation across generations for warming than for control populations, indicating stronger response to selection under warming conditions. As a measure for evolutionary rate, the phenotypic and sequence divergence between generations were assessed using the Haldane metric. Our approach combining comparisons between generations (allochronic) and between treatments (synchronic) in an experimental evolutionary field study, and linking population genomic data with phenotyping analyses provided a powerful test to detect rapid responses to selection. Our findings demonstrate that ragweed populations can rapidly evolve in response to climate change within a single generation. Short‐term evolutionary responses to climate change may aggravate the impact of some plant invaders in the future and should be considered when making predictions about future distributions and impacts of plant invaders. [ABSTRACT FROM AUTHOR]

The impacts of alien plants on native richness are usually assessed at small spatial scales and in locations where the alien is at high abundance. But this raises two questions: to what extent do impacts occur where alien species are at low abundance, and do local impacts translate to effects at the landscape scale?In an analysis of 47 widespread alien plant species occurring across a 1,000 km2 landscape, we examined the relationship between their local abundance and native plant species richness in 594 grassland plots. We first defined the critical abundance at which these focal alien species were associated with a decline in native α‐richness (plot‐scale species numbers), and then assessed how this local decline was translated into declines in native species γ‐richness (landscape‐scale species numbers).After controlling for sampling biases and environmental gradients that might lead to spurious relationships, we found that eight out of 47 focal alien species were associated with a significant decline in native α‐richness as their local abundance increased. Most of these significant declines started at low to intermediate classes of abundance. For these eight species, declines in native γ‐richness were, on average, an order of magnitude (32.0 vs. 2.2 species) greater than those found for native α‐richness, mostly due to spatial homogenization of native communities. The magnitude of the decrease at the landscape scale was best explained by the number of plots where an alien species was found above its critical abundance.Synthesis. Even at low abundance, alien plants may impact native plant richness at both local and landscape scales. Local impacts may result in much greater declines in native richness at larger spatial scales. Quantifying impact at the landscape scale requires consideration of not only the prevalence of an alien plant, but also its critical abundance and its effect on native community homogenization. This suggests that management approaches targeting only those locations dominated by alien plants might not mitigate impacts effectively. Our integrated approach will improve the ranking of alien species risks at a spatial scale appropriate for prioritizing management and designing conservation policies. [ABSTRACT FROM AUTHOR]

Changes in fashions and economic imperatives underlying plant introductions have a profound influence on the movement of species around the world. Using bamboo introductions into South Africa as a case-study, we explore these issues by assessing historical trends through a literature review and determining current human perceptions based on a questionnaire distributed via social media. We identify five main phases of introduction and distribution of bamboos in South Africa associated with: (1) the intra-African migration of people; (2) the arrival of Europeans; (3) growth of the agricultural and forestry sectors; (4) small-scale domestic use by landowners; and (5) the rise of the "green economy." Our narrative is built around 27 alien bamboo species (taxa mentioned in the literature that could be linked to currently accepted nomenclature). Bamboos were among the first plants introduced to South Africa by European settlers, and they are still used and valued by many landowners, although on a small-scale. Bamboos now create conflicts of interest because they are both valued and perceived to be weeds (the latter particularly by people who do not utilise them). [ABSTRACT FROM AUTHOR]

In the current context of ongoing global change, the understanding of how the niches of invasive species may change between different geographical areas or time periods is extremely important for the early detection and control of future invasions. We evaluated the effect of climate and non-climate variables and the sensitivity to various spatial resolutions (i.e. 1 and 20 km) on niche changes during the invasion of Taraxacum officinale and Ulex europaeus in South America. We estimated niche changes using a combination of principal components analyses ( PCA) and reciprocal Ecological Niche Modelling ( rENM). We further investigated future invasion dynamics under a severe warming scenario for 2050 to unravel the role of niche shifts in the future potential distribution of the species. We observed a clear niche expansion for both species in South America towards higher temperature, precipitation and radiation relative to their native ranges. In contrast, the set of environmental conditions only occupied in the native ranges (i.e. niche unfilling) were less relevant. The magnitude of the niche shifts did not depend on the resolution of the variables. Models calibrated with occurrences from native range predicted large suitable areas in South America (outside of the Andes range) where T. officinale and U. europaeus are currently absent. Additionally, both species could increase their potential distributions by 2050, mostly in the southern part of the continent. In addition, the niche unfilling suggests high potential to invade additional regions in the future, which is extremely relevant considering the current impact of these species in the Southern Hemisphere. These findings confirm that invasive species can occupy new niches that are not predictable from knowledge based only on climate variables or information from the native range. [ABSTRACT FROM AUTHOR]

Establishment and spread of organisms after long-distance dispersal often involve changes to the mating systems. Here, we tested for increased compatibility under a mate limitation scenario after long-distance dispersal of the tristylous Oxalis pes-caprae , a South African geophyte invasive in regions with Mediterranean climate. We investigated variation in the expression of the trimorphic incompatibility system in plants from 16 native populations covering the entire distribution range in South Africa, and 18 invasive populations from the western Mediterranean basin by performing controlled hand-pollinations. After legitimate pollinations, native plants had higher fruit and seed set than invasives, while after illegitimate pollinations (self- and intramorph pollinations), invasives were more successful than natives. We detected morph-specific differences in the weakening of the incompatibility system and within-population variability in the expression of the incompatibility reactions for invasive plants. Additionally, the offspring obtained after illegitimate pollinations was able to germinate, survive and flower under glasshouse conditions. Our results provide experimental evidence for differences in the expression of the incompatibility system between native and invasive populations of O. pes-caprae after introduction and under strong compatible mate’s limitation. The weakening in the incompatibility system reported here for the L- and M-morphs might possibly constitute an additional strategy for reproductive assurance in the invaded range of the Mediterranean basin. [ABSTRACT FROM AUTHOR]

In order to prevent emerging infective diseases (EIDs), which increasingly threaten trees of agro-forest and urban ecosystems, a thorough understanding of the factors causing them is necessary. In this paper we reviewed the current knowledge about the changes in the interplay between environment (with its components climate and human activity), pathogens and host plants that drive fungal EIDs of forest trees. We described seven groups of drivers that may be involved individually or together, at once or successively, in the emergence of an infective disease, and we illustrated them by examples. In the past century plant EIDs mostly resulted from the introduction of alien pathogens to new geographic areas as a consequence of international trade (i). However, other factors also played an important role, as for instance climate change (ii), which acts as a strong evolutionary force potentially enhancing the fitness or driving the expansion of the distribution range of pathogens, and/or weakening host plants i.e. predisposing them to infection. Global trade made geographically isolated pathogens spread beyond their natural range and hybridize with related species. Hybridization (iii) between previously isolated fungal pathogens has driven the emergence of new organisms with different and/or wider host range than the parental species. In some cases EIDs were caused by a hypervirulent strain of a known pathogen or by a completely new species, whose origin is still unclear (iv), which might be due to the development of novel traits or the acquisition of virulence from other species through horizontal gene transfer (HGT). The sudden appearance of unforeseen diseases may be driven by cryptic disease agents, i.e. microorganisms indistinguishable from known species except for unapparent traits involved in pathogenesis, by pathogens with an extended latency period, or by endophytes capable of turning into pathogens after environment changes (v). New associations between introduced insect vectors and native tree pathogens (vi), or vice versa, may result into more efficient transmission and extended host- or geographic range of pathogens. The global use of intensively managed forest plantations (vii) of non-native trees or of a small number of clones of the same species over huge areas has increased the attacks by pathogens, which were accidentally introduced and/or adapted to new hosts. While the idea of totally preventing new EIDs appears unrealistic, it may be possible to reduce their occurrence, and the related damages and costs, by managing the drivers of disease emergence. [ABSTRACT FROM AUTHOR]

The effectiveness of invasion depends on the interacting environmental factors and biology of the invader. The effects of these interactions are contingent on their contexts and difficult to predict. Among the most successful plant invaders in Europe are the goldenrods ( Solidago and Euthamia genera). We assessed the roles of ecological niche differentiation and historical contingency on their distribution in Silesia (Central Europe, studied area approximately 32,000 km). The distributions of the two most common species ( S. gigantea and S. altissima) were clumped, and the species dominated different areas. The distribution was unrelated to ecological niche differences but originates rather from the history of invasion and subsequent density-dependent spread; the species that was first introduced occupied available habitats and prevented the establishment of other species. Solidago canadensis was distributed randomly throughout the entire region and did not differ from S. altissima in its ecology. Euthamia graminifolia differed from the other goldenrods in habitat preferences and environmental requirements. Its distribution was strongly spatially structured, clumping around initial infestation sites. The extents of the differences resulting from ecological niche differentiation and the limitation of long-range dispersal are unclear. We argue that the under-representation of E. graminifolia in abandoned fields originates from the inhibition of establishment in habitats already occupied by other goldenrods. The results underline that the effect of historical contingency can be more prominent than ecological niche differentiation on invasive species distribution and invasion effectiveness. [ABSTRACT FROM AUTHOR]

Information on the pattern and rate of spread for invasive wood- and phloem-feeding insects, including the emerald ash borer (EAB) ( Agrilus planipennis Fairmaire), is relatively limited, largely because of the difficulty of detecting subcortical insects at low densities. From 2008 to 2011, grids of girdled and subsequently debarked ash ( Fraxinus spp.) detection trees were established across a >390 km 2 area encompassing two recently established EAB infestations in Michigan as part of the SLow Ash Mortality (SLAM) Pilot Project. Ash distribution and abundance were inventoried across the project area which included public and private forestland, a state park, and street trees in a small municipality. Spread rates of EAB from 2008 to 2011, based on larval presence in girdled detection trees, were estimated to be 1.2–1.7 km yr −1 in the larger, presumably older, infestation and 0.4–0.7 km yr −1 in the smaller infestation; suggesting a slower spread rate during the initial stages of population establishment. From 2009 to 2011, a total of 587 ash trees in the project area were trunk-injected with a highly effective, systemic emamectin benzoate insecticide. Potential effects of girdled ash trees and the systemic insecticide treatment on EAB spread were evaluated using a simulation model and a simple descriptive model of observed spread. Not surprisingly, density of trees treated with the insecticide was too low to exert a detectable effect on EAB spread. However, while the density of girdled trees was also relatively low, model results indicated a reduced spread of EAB out of areas containing girdled trees. [ABSTRACT FROM AUTHOR]

1. Phenotypic variation plays an important role in successful plant invasions. The spread of invasive species over large geographic ranges may be facilitated if plants can match their phenotype to local abiotic conditions. Spartina alterniflora, native to the United States, was introduced into China in 1979 and has spread over 19? of latitude along the eastern coast of China. 2. We studied patterns in vegetative growth and sexual reproduction of S. alterniflora at 22 sites at 11 geographic locations over a latitudinal gradient of ~2000 km from Tanggu (39.05°N, high latitude) to Leizhou (20.90°N, low latitude) in China. We further evaluated the basis of phenotypic differences by growing plants from across the range in a common garden for 2 growing seasons. 3. We found distinct latitudinal clines in plant height, shoot density and sexual reproduction across latitude. Some traits exhibited linear relationships with latitude; others exhibited hump-shaped relationships. We identified correlations between plant traits and abiotic conditions such as mean annual temperature, growing degree days, tidal range and soil nitrogen content. However, geographic variation in all but one trait disappeared in the common garden, indicating that variation largely due to phenotypic plasticity. Only a slight tendency for latitudinal variation in seed set persisted for 2 years in the common garden, suggesting that plants may be evolving genetic clines for this trait. 4. Synthesis. The rapid spread of Spartina alterniflora (S. alterniflora) in China has probably been facilitated by phenotypic plasticity in growth and reproductive traits. We found little evidence for the evolution of genetic clines in China, even though these exist for some traits in the native range. The considerable variation among clones, within provenances, that persisted in the common garden suggests a potential for the evolution of geographic clines in the future. Low fecundity of low-latitude S. alterniflora populations in China might result in a slower spread at low latitudes, but S. alterniflora is likely to continue to spread rapidly at high latitudes in China and into the Korean peninsula. [ABSTRACT FROM AUTHOR]

Aim Most studies on invasibility consider the characteristics of the habitats colonized. However, the success of the establishment of exotic species can be conditioned by the characteristics of the donor communities. In this study, we analyse the extent to which the distribution of exotic herbaceous species in Chile is conditioned either by the climatic characteristics of the recipient area or by the environmental features of the source areas on the Iberian Peninsula. Location Chile and the Iberian Peninsula (Portugal and Spain). Methods For Chile, we characterized the exotic species according to their current Chilean distribution and their region of origin. For the Iberian Peninsula, we compiled the floristic composition of 11,702 relevés. We classified each relevé according to key habitat characteristics (bioclimate, soil nutrient status and type of community associated with human activities) and calculated the percentage of species in common with Chile in different climatic regions therein. Results Over half of Chile's exotic species exhibited a geographic distribution related to the climate of the recipient area. The main donor communities were those associated with ruderal and arable land habitats, although their importance depended upon the climate in the recipient area. Correspondence was observed between the climatic characteristics of the communities in the source area and those of the recipient areas. Main conclusions The results highlight the influence of the characteristics of habitats in the source area on the successful establishment of exotic species in Chile. The relationships between source and recipient area are scale dependent, climate constituting the main driver at broad scale. Within each climatic region, the communities associated with habitats presenting greater anthropic influence act as the main donors. Both features indicate the existence of filters that select species pre-adapted to the climatic and habitat conditions in the recipient area. [ABSTRACT FROM AUTHOR]

In contrast to biological invasions, translocations of individuals within a species range are understudied, due to difficulties in systematically detecting them. This results in limited knowledge about the corresponding processes and uncertainties regarding the status of extant populations. European larch, a forest tree whose fragmented native distribution is restricted to the Alps and to other Central European mountains, has been massively planted for at least 300 years. Here we focus on the genetic characterization of translocations having taken place within its native range. Microsatellite variation at 13 nuclear loci and sequence data of two mitochondrial DNA fragments were analyzed on the basis of a comprehensive range-wide population sample. Two complementary methods ( and ) were used to infer translocation events based on nuclear data whereas mitochondrial data were used for validation of these inferences. Using , we found translocation events in a majority of populations. Additional cases of translocation and many instances of admixture were identified using , thanks to the clear-cut ancestral genetic structure detected in this species. In particular, a strong divide between Alpine and Central European populations, also apparent at mitochondrial markers, helped uncover details on translocation events and related processes. Translocations and associated admixture events were found to be heterogeneously distributed across the species range, with a particularly high frequency in Central Europe. Furthermore, translocations frequently involved multiple geographic sources, some of which were over-represented. Our study illustrates the importance of range-wide investigations for tracing translocations back to their origins and for revealing some of their consequences. It provides some first clues for developing suitable conservation and management strategies. [ABSTRACT FROM AUTHOR]

Aim A key aspect of effective invasive plant management is a clear understanding of natal ranges. In the balloon vine genus, Cardiospermum, uncertain native biogeographic ranges are hampering ongoing biological control efforts against invasive taxa in southern Africa. With the objective of minimizing non-target impacts, which are a major concern for conservation, we combine phylogenetic analyses with known native range distributions of selected Cardiospermum species to resolve unknown natal ranges for globally widespread balloon vines which occur in southern Africa. Location Argentina, Australia, Brazil, Fiji, Hawaii, Mayotte, Namibia, South Africa, Tanzania, Tahiti and Uganda. Methods Phylogenetic relationships and dispersal histories of known invasive and native populations of Cardiospermum species ( C. corindum, C. grandiflorum, C. halicacabum and C. pechuelii) were inferred from network and phylogeny reconstructions for two plastid genes ( rpl32 and trnL-F) to closely investigate relationships within and among balloon vine species. The timing of putative transoceanic dispersal events was determined from a dated nDNA (internal transcribed spacer, ITS) phylogeny using a relaxed molecular clock and a previously identified root age for the group. Results Both phylogenies (cp DNA and nDNA) and the haplotype network (cp DNA only) indicated no clear genetic structure for Cardiospermum halicacabum world-wide, that is incongruence between geography and evolutionary relatedness. Similarly, we found no global geographic structure in C. grandiflorum, with the exception of Hawaiian and Ugandan accessions which formed a distinct monophyletic clade. In contrast, deep divergence was identified for C. corindum between southern Africa and native South American populations, both within the haplotype network and phylogenetic trees (dated at 5.9-15.1 Ma). More surprising, however, was the observed close phylogenetic relationship between the true African balloon vine species, C. pechuelii and African C. corindum, with the former rendering C. corindum paraphyletic, supporting the native status of the latter in southern Africa. Main conclusions We conclude that C. halicacabum is likely non-native in southern Africa, while both C. corindum and C. pechuelii are native to southern Africa. We confirm the invasive status of C. grandiflorum in southern Africa and Australia but suggest that its status (native or invasive) be reviewed in other regions outside South America. We recommend that already-identified biological control agents with potential non-target impacts on C. corindum and C. pechuelii not be released against invasive Cardiospermum taxa in southern Africa and careful monitoring of such impacts for agents that have already been released prior to this study. [ABSTRACT FROM AUTHOR]

Aim Anderson & Stebbins (1954, Evolution, 8, 378-388) posited that human activities promote species hybridizations by creating opportunities for hybridization and new habitats for hybrids to persist through disturbances (i.e. the 'disturbance hypothesis'). While the first part of this hypothesis appears to be well supported, the second part has not been corroborated with empirical evidence, probably because of the lack of appropriate data. In this study, I (1) document the richness and distribution of hybrid plants in the United States; (2) examine the relationships between hybrids of different origins and between hybrid plants and native or exotic plants; and (3) examine possible mechanisms for these relationships and test the disturbance hypothesis. Location The United States. Methods The richness and distribution of plant hybrids was examined at the county level according to origin, that is, formed between native-native species ( N × N), native-exotic species ( N × E) and exotic-exotic species ( E × E), using data from the Biota of North America Program. Results The three hybrid types ( N × N, N × E and E × E) were positively related to each other and showed stronger positive relationship with exotic richness than with native richness. They also exhibited similar spatial patterns, with richness hotspots concentrated in the north-east United States and Great Lakes region. However, the richness of hybrids of exotic origin ( E × E and N × E) was not related to county area, as often observed for native species; instead, it showed strong positive relationships with human population density. Thus, the overall patterns of hybrid richness and distribution support the 'disturbance hypothesis'. Main conclusions The results are generally consistent with the disturbance hypothesis. The relationship between the number of hybrids of exotic origin and overall exotic richness provided stronger evidence for human-induced than for naturally caused hybridization, although other possible explanations may also exist. [ABSTRACT FROM AUTHOR]

Aim Invasive alien species are a threat to biodiversity and can harm resident plants, animals, humans and infrastructure. To reduce deleterious effects, effective management planning for invasive plants is required. Currently, the effectiveness of management is primarily optimized locally through eradication of individual populations. By contrast, spatial prioritization of control activities at the landscape level has received less attention, despite its potential to improve management planning in complex landscapes, especially under budget constraints. Location North-eastern Switzerland, Europe. Methods We used a dynamic simulation model to evaluate the effectiveness of spatially designed management planning for controlling the expansion of three invasive alien plants ( IAPs; Heracleum mantegazzianum, Impatiens glandulifera and Reynoutria japonica) across a heterogeneous landscape in North-eastern Switzerland. The model predicted the spread of IAPs from their current distribution under constraints of 361 control options differing in local intensity, frequency, duration, area and spatial prioritization of eradication measures. Results Our results demonstrate that IAP-control actions under a restricted budget are more effective if control actions are spatially prioritized. Most effective spatial treatments generally prioritized small populations in the case of the annual species and large populations in the case of the perennial species. Further, applying intensive control at early stages generally increased effectiveness of control. Main conclusions For IAP-management planning, our findings suggest that control should be applied early when IAPs start spreading, to maximize success or minimize costs. Further, spatial prioritization schemes are particularly useful under limited financial means for IAP-management. Finally, our modelling approach may serve as a proof of concept to evaluate the effectiveness of control actions of various IAPs in complex landscapes. [ABSTRACT FROM AUTHOR]

Albania, whose territory comprises many types of habitats and is characterized by a rich biological diversity, is particularly vulnerable to the threats posed by alien invasive species. The spread of invasive alien species is creating complex and far-reaching challenges that threaten both the natural biological riches of the earth and the well-being of our people. While the problem is global, the nature and severity of the impacts on society, economic life, health, and natural heritage are distributed unevenly across nations and regions. Some aspects of the global invasive alien species (IAS) problem require solutions tailored to the specific values, needs, and priorities of nations while others call for consolidated action by the larger world community. Preventing the international movement of invasive alien species and coordinating a timely and effective response to invasions requires cooperation and collaboration among governments, economic sectors, non-governmental organizations, and international treaty organizations. Many features have been attributed to invasive species and invaded ecosystems, but none are universal and invasive species tend to have a suite of traits rather than all of themThe large numbers of alien organisms introduced into Albania do not generally endanger the biodiversity on a large scale. [ABSTRACT FROM AUTHOR]

Aim Use of local-scale non-native plant species ( NNS) distribution models has the potential to decrease survey effort and improve population prioritization for management. We developed and evaluated data collection methods and minimum sampling requirements to inform local-scale models of NNS distribution. We also evaluated overall model predictive performance for 16 species at two sites and determined how classes of variables contributed to model performance and suggest invasion drivers. Location Wyoming and Idaho, USA Methods A simulation study was used to test the efficiency of different sampling methods to predict imposed species distributions. Empirical distribution models of species occurrence data from two environmentally disparate sites were cross-validated at increasing sample sizes, and the asymptotic maximum predictive performance and relative contribution of classes of variables were determined for 16 NNS. Results Transect sampling was the most efficient method for maximizing model performance after accounting for logistics. Minimum sample sizes to reach model maximum predictive performance were similar for the simulation (< 0.5% of study area) and empirical studies (mean of 0.13% using transects). Maximum predictive performance tended to be greater at the site with steeper environmental gradients, and topo-climatic/biotic variables were most important to model improvement. Main conclusions Local-scale SDMs can be useful to NNS managers. Using transect methodology, enough data can be collected (ca. 0.13% of the management area) to fit models within logistical/budgetary constraints. These models are most predictive for well-established species as opposed to new invaders and in areas with steeper environmental gradients. Finally, topo-climatic/biotic predictors are the most important variables for predicting more established species, but disturbance and dispersal limitation should be considered and quantified to ensure variables associated with dominant processes are included in the SDM. [ABSTRACT FROM AUTHOR]

Spatial distribution of alien trees was studied on Pre-Delta National Park (PNPD-Entre Ríos, Argentina), by distance sampling techniques. Potential distribution was modelled by Kriging interpolation technique. Generated maps were overlapped with PNPD zonification map and environmental units map. We recorded forest structural data, tree phenology and tree control management actions, in order to characterize the processes of invasion. We obtained maps of potential distribution of Melia azedrach, Broussonetia papyrifera, Ligustrum lucidum, Brachychiton populneus, Fraxinus sp. and Morus alba L. The latter was the dominant species in all studied sectors (cliffs, islands and highlands). As for the management actions carried out with trees of the PNPD, about 50% of the specimens of M. alba subjected to mechanical control (banding technique) showed regrowth, indicating its high survival capacity. [ABSTRACT FROM AUTHOR]

In California prairies, native perennial grasses have been almost entirely replaced by Eurasian winter-annual grasses. Landscape-scale descriptions of perennial versus annual grass distribution are lacking. To quantify perennial persistence in California grasslands, 50 randomly selected grassland meadows were sampled within three latitudinal belts of central California, from the Pacific coast inland to the Central Valley. Native perennial grasses were present at all but four of the sampling sites, although usually at low density. Proximity to the Pacific coast was positively correlated to perennial grass cover at all latitudes. Annual degree days above 18 °C and increasing slope were significantly negatively correlated to perennial grass dominance, and average warm season precipitation was significantly positively correlated to perennial dominance. Cover of non-native annual grasses was significantly lower in prairies <2 km from the coast than in all other sites. Non-native perennial grasses were occasionally important grassland community components at sites near the coast, but relatively uncommon inland. These results suggest that environmental conditions near the California coast tend to increase the success of perennial grasses, including exotic perennials. Intensity and duration of seasonal water stress likely play a central role in determining perennial grass distribution in California. [ABSTRACT FROM AUTHOR]

Abstract: Species distribution modeling is playing an increasingly prominent role in ecology and global change biology, owing to its potential to predict species range shifts, biodiversity losses, and biological invasion risks for future climates. Such models are now well-established as important tools for biological conservation. However, the lack of high-resolution data for future climate scenarios has seriously limited their application, particularly because of the scale gap between general circulation models (GCMs) and species distribution models (SDMs). A recently introduced change-factor downscaling technique provides a convenient way to build high-resolution datasets from GCM projections. Here, we present a high-resolution (10’×10’) global bioclimatic dataset (BioPlant) for plant species distribution. The 15 bioclimatic variables we select are considered those most eco-physiologically relevant. They can be easily calculated from climatic variables common to all GCM projections. In addition to the traditional classes of variables regarding temperature and precipitation, the BioPlant dataset emphasizes the interactions between temperature and precipitation, particularly within plant growing seasons. A preliminary visual analysis shows that variations among GCMs are more significant on a species range scale than on a global scale. Thus, the formerly advocated ensemble modeling method should be applied not only to different SDMs, but also to various GCMs. Statistic analysis suggests that divergent behavior among GCM variations for temperature class variables and classes of precipitation variables requires special attention. Our dataset may provide a common platform for ensemble modeling, and can serve as an example to develop higher-resolution regional datasets. [Copyright &y& Elsevier]

Abstract: We present the first detailed survey of a population of Acacia paradoxa DC. (syn. Acacia armata R.Br.), Kangaroo Thorn, in South Africa. The species is listed under the Conservation of Agricultural Resources Act as a category 1 invasive plant and, until 2008, was being managed as part of Working for Water''s general alien clearing operations. Acacia paradoxa is currently restricted to a small population (~11,350 plants over ~295 ha) on the northern slopes of Devil''s Peak, Table Mountain National Park in the Western Cape. Its distribution is highly clumped, and at a local scale it has formed thick stands of up to 20 plants m−2. Using a bioclimatic model we predict that it has a large potential distribution in South Africa, especially along the southern coast. We confirmed the categorisation of A. paradoxa as a potential landscape transformer that requires immediate control by conducting a formal risk assessment using the Australian Weed Risk Assessment system. However, the population appears to be spreading slowly, and, while there is a significant seed-bank in some places (~1000 seeds m−2), this is largely restricted to below the canopy of existing plants. Therefore, the population has not and likely will not rapidly spread in area, and so containment is feasible. Dedicated and thorough annual follow ups are required because plants can produce seeds when they are 1 year old and standard clearing operations have missed flowering plants. [Copyright &y& Elsevier]

Aim Given that urban landscapes often act as a point of entry for many non-native species and urban development continues to increase as the human population rapidly expands, an understanding of the interaction between urbanization and non-native plant species is important both in the control of potentially invasive species and in the conservation of native biodiversity. We investigated the spatial and temporal relationship between urban land cover and the distribution of non-native species in Britain using two floristic data sets collected at two different time periods: 1987–88 and 2003–04. Location UK. Methods Using floristic data collected by the Botanical Society of the British Isles in 1987–88 (Monitoring Scheme) and 2003–04 (Local Change) in conjunction with habitat data obtained from the Land Cover Map of the UK, we conducted multiple regression analyses both within and between years on both groups of species (natives, neophytes and archaeophytes) and individual species. Results Neophytes (alien species introduced after 1500) were very strongly associated with urban land cover in both time periods and do not appear to be spreading out of urban habitats into the wider countryside. Archaeophytes (alien species introduced before 1500), however, showed a strong association with urban habitats in the earlier 1988 data set but no longer showed this association in the 2004 data set. Analysis at the individual species level showed that a large percentage of alien plant species, particularly archaeophytes, were not strongly associated with urban land cover or were negatively associated with such habitats. Main conclusions Our results suggest that there has been a reduction in the urban association of archaeophytes that is likely to have resulted from the recovery of archaeophytes associated with non-urban (especially arable) habitats, following their decline in mid-20th century, rather than from the movement of aliens into the wider countryside from urban habitats. [ABSTRACT FROM AUTHOR]

Aim Recent studies using vegetation plots have demonstrated that habitat type is a good predictor of the level of plant invasion, expressed as the proportion of alien to all species. At local scale, habitat types explain the level of invasion much better than alien propagule pressure. Moreover, it has been shown that patterns of habitat invasion are consistent among European regions with contrasting climates, biogeography, history and socioeconomic background. Here we use these findings as a basis for mapping the level of plant invasion in Europe. Location European Union and some adjacent countries. Methods We used 52,480 vegetation plots from Catalonia (NE Spain), Czech Republic and Great Britain to quantify the levels of invasion by neophytes (alien plant species introduced afterad 1500) in 33 habitat types. Then we estimated the proportion of each of these habitat types in CORINE land-cover classes and calculated the level of invasion for each class. We projected the levels of invasion on the CORINE land-cover map of Europe, extrapolating Catalonian data to the Mediterranean bioregion, Czech data to the Continental bioregion, British data to the British Isles and combined Czech–British data to the Atlantic and Boreal bioregions. Results The highest levels of invasion were predicted for agricultural, urban and industrial land-cover classes, low levels for natural and semi-natural grasslands and most woodlands, and the lowest levels for sclerophyllous vegetation, heathlands and peatlands. The resulting map of the level of invasion reflected the distribution of these land-cover classes across Europe. Main conclusions High level of invasion is predicted in lowland areas of the temperate zone of western and central Europe and low level in the boreal zone and mountain regions across the continent. Low level of invasion is also predicted in the Mediterranean region except its coastline, river corridors and areas with irrigated agricultural land. [ABSTRACT FROM AUTHOR]

For a species rapidly expanding its geographic range, such as during biological invasion, most alleles in the introduced range will have their evolutionary origins in the native range. Yet, the way in which historical processes occurring over evolutionary time in the native range contribute to the diversity sampled during contemporary invasion is largely unknown. We used chloroplast DNA (cpDNA) gene genealogies and coalescent methods to study two congeneric plants, Silene latifolia and S. vulgaris. We examined how phylogenetic diversity was shaped by demographic growth and historical range expansions in the native European range, and how this history affected the diversity sampled during their recent invasion of North America. Genealogies from both species depart from neutrality, likely as a result of demographic expansion in the ancestral range, the timing of which corresponds to shortly after each species originated. However, the species differ in the spatial distribution of cpDNA lineages across the native range. Silene latifolia shows a highly significant phylogeographic structure that most likely reflects different avenues of the postglacial expansion into northern Europe from Mediterranean refugia. By contrast, cpDNA lineages in S. vulgaris have been widely scattered across Europe during, or since, the most recent post-glacial expansion. These different evolutionary histories resulted in dramatic differences in how phylogenetic diversity was sampled during invasion of North America. In S. latifolia, relatively few, discrete invasion events from a structured native range resulted in a rather severe genetic bottleneck, but also opportunities for admixture among previously isolated lineages. In S. vulgaris, lack of genetic structure was accompanied by more representative sampling of phylogenetic diversity during invasion, and reduced potential for admixture. Our results provide clear insights into how historical processes may feed forward to influence the phylogenetic diversity of species invading new geographic ranges. [ABSTRACT FROM AUTHOR]

Aim This paper reviews the main geographical determinants of naturalization in plants. Location Global. Methods Comparative studies of large data sets of alien floras are the main source of information on global patterns of naturalization. Results Temperate mainland regions are more invaded than tropical mainland regions but there seems to be no difference in invasibility of temperate and tropical islands. Islands are more invaded than the mainland. The number of naturalized species in temperate regions decreases with latitude and their geographical ranges increase with latitude. The number of naturalized species on islands increases with temperature. Naturalized species contribute to floristic homogenization, but the phenomenon is scale-dependent. Main conclusions Some robust patterns are evident from currently available data, but further research is needed on several aspects to advance our understanding of the biogeography of naturalization of alien plants. For example, measures of propagule pressure are needed to determine the invasibility of communities/ecosystems/regions. The patterns discussed in this paper are derived largely from numbers and proportions of naturalized species, and little is known about the proportion of introduced species that become naturalized. Further insights on naturalization rates, i.e. the proportion of aliens that successfully naturalize within regions, and on geographical and other determinants of its variation would provide us with better understanding of the invasion process. Comparative studies, and resulting generalizations, are almost exclusively based on numbers of species, but alien species differ in their impact on native biodiversity and ecosystem processes. [ABSTRACT FROM AUTHOR]

Biological invasion by alien invasive species is now recognized as one of the major threats to native species and ecosystems. Parthenium weed ( Parthenium hysterophorus L.), an alien invasive weed species, is spreading throughout Pakistan. Worldwide, it has been designated as one of the most troublesome weed species. The adverse effects of this weed on human beings, livestock, crop production, and biodiversity are well-documented. As a result of a lack of information on its spread in Pakistan since its invasion, a phytosociological survey, with special reference to parthenium weed, was carried out in Islamabad from August–October 2002. Six main sectors of Islamabad were selected for sampling. The phytosociological survey of these sectors of Islamabad revealed a total of 30 weed species to be associated with P. hysterophorus. The survey also showed a high relative frequency, relative density, and importance value of P. hysterophorus in general; however, the percentage relative frequency of the weed in these sectors ranged from 10.6–30.3%. This survey revealed that P. hysterophorus had an appreciable degree of sociability with Senna occidentalis (L.) Link, Malvastrum coromandelianum (L.) Garcke and Lantana camara (L.). The data on the association of L. camara with P. hysterophorus suggests that a transition phase of competition or succession is in progress between these two alien species. The population of many common medicinal plants growing in the wastelands of Islamabad might be rapidly declining because of the aggressive colonization by P. hysterophorus. The ever-increasing infestation of this weed in urban areas also poses a serious threat to the health of the inhabitants of Islamabad. [ABSTRACT FROM AUTHOR]

We studied variability in the abundance of small individuals of an invasive mussel (Musculista senhousia) across the depth distribution of a native marine angiosperm, eelgrass (Zostera marina). Adult mussels and eelgrass have a disjunct local distribution, each limiting the other in complex ways. To assess whether eelgrass also influenced the distribution of juvenile mussels, we sampled inside and outside eelgrass beds in one site in Mission Bay and two in San Diego Bay, California, USA. We sampled mussels in size classes 0.26-0.50 mm, 0.5 1-1.00 mm, 1.10-2.00 mm and> 2.00 mm from September 1997 to April 1999. We also monitored gonad development in larger mussels and in situ growth of mussels ... 2 mm tagged with the chemical marker calcein. Spatial and temporal variations in mussel abundances were high but seasonal patterns were roughly similar at San Diego Bay sites; very few mussels were found in Mission Bay. Mussels with full gonads were found year-round in San Diego Bay, as were mussels in the smallest size class (with a large peak in fall and a smaller secondary one in spring), suggesting that many of the smallest mussels represent recruitment. The observation that most, although not all, tagged mussels increased in size provides further support for recruitment. Some of the highest numbers of mussels in the smallest size class were found inside eelgrass beds, indicating that eelgrass does not restrict and may actually enhance the distribution of very small mussels. The disjunct distribution of adult mussels and eelgrass thus is apparently established primarily postrecruitment. M. senhousia is capable of year-round repro- duction, recruitment and growth, and thus is poised to preempt space from eelgrass following any disturbance that results in eelgrass declines, such as habitat fragmentation, eutrophication, or disease. [ABSTRACT FROM AUTHOR]

Plant invasions have been attracting increasing attention from ecologists because of their worldwide environmental impacts and huge economic costs. Research on the characteristics of the recipient regions is essential for understanding the process of plant invasion. However, few previous studies on invasibility of habitats include social factors, although human activities are critical in the process of plant invasion. China is a vast country with high plant species diversity and a long history of introduction of exotic plant species and is particularly vulnerable to invasive plant species. Alien plant species are widespread in the country. Therefore, the study of invasive plants in China is urgent in practice and theoretically important for developing invasion ecology. For the present study, 126 species were selected to represent the major invasive plant species in China. We then collected data on their species richness in 31 provincial administrative units of China and performed Spearman rank correlations between species richness and possible natural and socio-economic factors. We found that socio-economic factors, such as human density and GDP, correlated positively with the species richness of invasive plants in China. In conjunction with the natural and socio-economic correlations in the study of regional distribution pattern of the major invasive plants, we discussed the factors influencing the regional distribution pattern of the major invasive plants in China. We suggest that native plant species richness was mainly determined by the natural conditions of the regions, while invasive species richness was influenced by natural conditions and human disturbance together. [ABSTRACT FROM AUTHOR]

Ocean warming associated with global climate change renders marine ecosystems susceptible to biological invasions. Here, we used species distribution models to project habitat suitability for eight invasive ascidians under present-day and future climate scenarios. Distance to shore and maximum sea surface temperature were identified as the most important variables affecting species distributions. Results showed that eight ascidians might respond differently to future climate change. Alarmingly, currently colonized areas are much smaller than predicted, suggesting ascidians may expand their invasive ranges. Areas such as Americas, Europe and Western Pacific have high risks of receiving new invasions. In contrast, African coasts, excluding the Mediterranean side, are not prone to new invasions, likely due to the high sea surface temperature there. Our results highlight the importance of climate change impacts on future invasions and the need for accurate modelling of invasion risks, which can be used as guides to develop management strategies. • We mapped current and future potential distributions of 8 invasive ascidians. • Distance to shore and max sea surface temperature were crucial variables. • The majority of invaders have occupied a small portion of their potential habitats. • Four species will have substantial increase in potential ranges as time progresses. [ABSTRACT FROM AUTHOR]

The global database of invasive trees and shrubs (Richardson & Rejmánek, 2011; Diversity Distrib. 17, 788-809) has been updated, resulting in a total of 751 species (434 trees and 317 shrubs) from 90 families. Ten originally listed species were deleted (synonyms, inconclusive identification, etc.) and 139 additional invasive species (86 trees and 53 shrubs) are now included in the database. For many species, new records on their adventive distributions are added. The updated database also includes the native ranges for all listed species. [ABSTRACT FROM AUTHOR]