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Understanding the responses of non‐native plants to climate change while accounting for biotic interactions is key to predicting and mitigating future invasion risks. Non‐native invasive plants may benefit from or decline in the face of climate change, relative to native competitors. Non‐native plants might also suffer less than native plants from natural enemies such as herbivores, which could give non‐natives a competitive advantage. However, we lack an understanding of how non‐native plants will compete with native plants in a warming climate, while accounting for the effects of herbivore pressure. To test the potential interactions between warming, herbivore pressure and competition, we set up a common‐garden experiment in Trondheim, Norway, using five non‐native plants growing either alone or in competition with a native plant community. These plants were subjected to herbivore exclusion and artificial warming treatments, using open‐top chambers. We found that under warming, three non‐native species had greater biomass and all five species were taller than when grown without warming. Competition with native species reduced the biomass of three non‐native species and herbivore exclusion resulted in taller plants for three non‐native species. Native community biomass was not affected by either warming or herbivore exclusion. Furthermore, the native community was not affected by competition with any non‐native plant except Centaurea montana, which resulted in lower native community biomass, suggesting that C. montana is likely to be the most detrimental of these non‐native species to native communities. Competition with natives reduced the positive effects of warming on biomass for only one species, Alchemilla mollis. Our study strongly suggests that a warming climate may benefit invasive plants more than native plants, but for some species these effects will be mediated by biotic interactions in idiosyncratic ways, depending on the identity of both native and non‐native species. This will present a challenge to predicting plant invasion success under climate change while accounting for biotic interactions. [ABSTRACT FROM AUTHOR]

In response to non‐native plant invasions, many governments have established noxious weed lists to control and eradicate introduced invasive plants. However, invasive agronomic species are often unregulated, and the extent of their invasion across habitat types has never been determined.Using vegetation surveys across 222 plots, we investigated the contribution of agronomic versus noxious non‐native species to the levels of invasion across seven habitat types in central Canada.Although agronomic non‐native species, such as Poa pratensis and Bromus inermis, only made up 21.3% of the non‐native species pool, they accounted for 43.6% of non‐native plant species frequency and 74.4% of relative non‐native plant cover. They were also disproportionately overrepresented compared with noxious non‐native species across all habitat types, except saline marshes.The overabundance of agronomic non‐native plants in central Canada is likely the legacy of cultivar breeding, intentional seeding of introduced forage species and a lack of incentive for the use of native species.Synthesis and applications: Decelerating the invasion by agronomic non‐native plants will require approaches beyond noxious weed lists and initiatives in research, policy and education. These tools can include incentives to use native seed material, for example, in reclamation and forage and turf production, to reduce propagule pressure from invasive agronomic non‐native plants. [ABSTRACT FROM AUTHOR]

The Andes mountain range in South America has a high level of endemism and is a major source of ecosystem services. The Andes is increasingly threatened by anthropogenic disturbances that have allowed the establishment of non-native plants, mainly in the lower elevation areas. However, synergies between climate change and anthropogenic pressure are promoting the spread of non-native plants to higher elevation areas. In this article, we evaluate and identify the main non-native plants invading Andean ecosystems, and assess their taxonomic families, growth forms and distribution patterns. Based on a systematic literature review, we identified the importance of climatic and anthropogenic factors as drivers of non-native species establishment in Andean ecosystems and the main impacts of non-native plants in the Andes. We then identified research gaps across each biogeographic region in the Andes. Finally, we highlight key elements to better tackle the problem of non-native plant invasions in Andean ecosystems, including the need for a systematic monitoring of invasion patterns and spread (e.g. MIREN protocol) and a common policy agenda across international borders for the prevention and management of non-native plants in this highly vulnerable region. [ABSTRACT FROM AUTHOR]

Introduced plants can have long-lasting and irreversible effects on the communities and ecosystems they invade. A critical step towards understanding the legacy of plant introductions is the characterisation of changes in the invaded plant communities and how these changes are related to biogeochemical modifications. Here, we addressed this issue by comparing the impacts of two large invasive herbs, Gunnera tinctoria and Impatiens glandulifera, on the compositional, functional, and phylogenetic structure of the standing vegetation (above-ground communities) and the soil seed bank (below-ground communities). The introduction of both invasive species was associated with a significant decrease in above-ground species richness, with subsequent changes in the functional diversity and phylogenetic dispersion of the vegetation. Yet, these invaders differed in their long-term impacts and the reversibility of any modifications they caused. While G. tinctoria invasions resulted in phylogenetically clustered communities (both above and below-ground) that were clearly distinct from uninvaded ones, seed bank communities invaded by I. glandulifera were indistinguishable from uninvaded ones, despite major compositional changes above-ground. Further, we found alterations in nutrient cycling associated with G. tinctoria invasions that could facilitate its local persistence and exacerbate any negative effects on native diversity. Our findings suggest a high susceptibility of pre-invasion above-ground communities to colonisation by distantly related herbs. However, the seed banks showed a degree of resilience against both invaders, with no major differences in species richness. Ultimately, differences in the impacts of these large invasive herbs suggest that dominance in the vegetation and a large stature are poor predictors of long-term plant community changes, including regeneration potential from seed, which are associated with plant introductions. [ABSTRACT FROM AUTHOR]

Although relatively infrequent, invasions by non-native plants at high latitudes are increasingly recognized as an emerging problem. Churchill, MB, Canada is unusual as over 100 non-native species have been found in human-disturbed areas, making it an outlier amongst subarctic habitats. Although these non-native species have persisted almost exclusively within town, some occur in isolated locations throughout the local road network. Most of these non-native species have been observed in areas with a history of soil movement (e.g., for construction or road repairs), suggesting that they have been moved within the soil, likely either germinating from seeds or growing clonally from root and rhizome fragments. Using a greenhouse experiment, we found evidence that soils from human-disturbed sites can contain a substantial non-native seed bank. In particular, we grew a significantly higher number of non-native seedlings from translocated soils compared with uninvaded soils. These germinated non-native species are native to Europe but have widely invaded temperate regions. This study provides the first direct evidence that movement of seed-contaminated soil is a significant source of local non-native species spread. Future warming in Arctic regions may increase seed production of these species, leading to increased spread and persistence via contaminated soil. [ABSTRACT FROM AUTHOR]

We aimed to explore how the invasion of the alien plant Solanum elaeagnifolium affects soil microbial and nematode communities in Mediterranean pines (Pinus brutia) and maquis (Quercus coccifera). In each habitat, we studied soil communities from the undisturbed core of both formations and from their disturbed peripheral areas that were either invaded or not by S. elaeagnifolium. Most studied variables were affected by habitat type, while the effect of S. elaeagnifolium was different in each habitat. Compared to maquis, the soil in pines had higher silt content and lower sand content and higher water content and organic content, supporting a much larger microbial biomass (PLFA) and an abundance of microbivorous nematodes. The invasion of S. elaeagnifolium in pines had a negative effect on organic content and microbial biomass, which was reflected in most bacterivorous and fungivorous nematode genera. Herbivores were not affected. In contrast, in maquis, organic content and microbial biomass responded positively to invasion, raising the few genera of enrichment opportunists and the Enrichment Index. Most microbivores were not affected, while herbivores, mostly Paratylenchus, increased. The plants colonizing the peripheral areas in maquis probably offered a qualitative food source to microbes and root herbivores, which in pines was not sufficient to affect the much larger microbial biomass. [ABSTRACT FROM AUTHOR]

Many invasion hypotheses propose biotic interactions as the main mechanism to explain non‐native species' success. Despite the evidence that the strength of biotic interactions varies with abiotic context, it remains unclear whether the importance of the different mechanisms proposed to explain invasion predictably varies with the abiotic context and whether this variation is consistent across different growth forms.We reviewed studies at a global scale to evaluate whether evapotranspiration, latitude, precipitation and temperature influence the importance of disturbance, enemy release, facilitation, and novel weapons mechanisms to explain non‐native plant invasions. In total, we calculated 171 effect sizes for ~300 non‐native plant species covering a wide range of environmental conditions and growth forms.Environmental context and plant growth form influenced the role played by each invasion mechanism. The importance of disturbance in facilitating invasion exhibited a quadratic relationship with latitude and temperature, and decreased with increasing precipitation. In mixed communities and trees, disturbance was mediated by either evapotranspiration, latitude, precipitation or temperature. Enemy release exhibited a quadratic relationship with evapotranspiration, latitude and precipitation, and it was positively related to temperature. The importance of enemy release was also contingent on growth form and was highly context‐dependent. Enemy release responses for grasses, and trees were modulated by either evapotranspiration, latitude, precipitation or temperature. The importance of facilitation decreased with increasing temperature. In forbs, facilitation decreased with evapotranspiration and temperature. The importance of novel weapons was more strongly confirmed for studies conducted at lower evapotranspiration, precipitation and higher latitudes, and exhibited a quadratic relationship with temperature.Synthesis. Our results show that environmental conditions not only filter non‐native species depending on physiological tolerances but may also influence the importance of invasion mechanisms. [ABSTRACT FROM AUTHOR]

We continue the inventory of alien vascular plants of Kyrgyzstan, with emphasis on the time and pathways of introduction of the species and their current status in the territory. Each taxon is discussed in the context of plant invasions in Central Asia. This work is a further development of the preliminary checklist of alien plants of Kyrgyzstan, which was compiled for the Global Register of Introduced and Invasive Species in 2018. [ABSTRACT FROM AUTHOR]

Aim: Biological invasion has become one of the most important environmental concerns in many countries, with considerable time, money and effort being spent in the prevention and eradication of invasive species. Since mineral ores tend to harbour seeds from the local plants, our aim was to study the non‐native plants collected in Chinese ports to understand the influence of global ore trade on biological invasion. Location: China. Methods: We surveyed 75 ore heaps across six types of ore in 22 Chinese port cities from 2010 to 2016 and collected 737 voucher specimens of non‐native plants, out of which 709 specimens were traced to the country of origin. Using the software Maxent, we evaluated the risk of invasion from these non‐native plants based on the global ore trade flow, traced their route and predicted the regions in China most vulnerable to invasion by these plants. Results: Of the 407 non‐native plant species identified, most were from India, followed by Malaysia, Swaziland, Mexico, and Iran. Taxonomically, there were representations from 49 families, notably Fabaceae, Poaceae, Asteraceae and Solanaceae. The non‐native plant species were represented by varying number of species, from a single specimen to 179. Analysis of the invasion risk indicated that the entire coast of China was at high risk. Furthermore, two major potential introduction pathways were also identified, namely the Yangtze drainage basin and the land from the Gulf of Tonkin to Sichuan Basin. Main conclusion: An important pathway for the invasion of non‐native plants is the inadvertent transportation of seeds through global ore trade networks. Based on this study, we suggest greater monitoring and cooperation in the international ore trade for better management, and creating public awareness of the dangers of non‐native species to help minimize the risk of transporting non‐native plants by the global ore trade network. [ABSTRACT FROM AUTHOR]

Ecosystem property and function can be considerably altered by changes in agricultural land use. Despite the expansion of abandoned fields in temperate humid areas worldwide, little is known about how ecosystem C stock and its partitioning change with secondary succession, especially under the invasion of non-native, fast-growing plants. Using a paired-plot approach, we investigated how plant community type (native vs. non-native, the latter represented by Solidago altissima) influences temporal changes in ecosystem C pools in abandoned paddy fields. Thirty-seven plots of control (paddy) and abandoned (2–37 years of succession) pair having similar soil types under the humid temperate climate of Japan were selected for this study. We detected a net loss of ecosystem C in the first 15.2 years, followed by a gradual C gain. Apparent maximal C gain (up to 10 Mg C ha−1) was observed approximately 30 years after abandonment, based on a smooth spline model. The initial C loss was largely attributed to decomposition in mineral-associated soil C, owing presumably to the rapid decay of the C accumulated under temporally anaerobic paddy. While no detectable difference was found in the ecosystem C stock between plots dominated by S. altissima and native plants, the S. altissima-dominated plots showed significantly lower litter C stock. We therefore conclude that, despite the rapid growth and high aboveground biomass of S. altissima, its invasion did not increase ecosystem C storage in the studied region; these findings highlight the absence of ecological benefits associated with S. altissima invasion. [ABSTRACT FROM AUTHOR]

The number and rate of non‐native plant invasions in forests have been steadily increasing over the last century with profound consequences for the composition, structure and functioning of these ecosystems. While multiple regional, landscape and local environmental factors are known to drive the spread of non‐native invasive plant species (NNIPS) into forests, such factors have rarely been analysed within a unified analytical framework allowing for the assessment of their relative importance, possible non‐linear behaviour and interactions. Obtaining such knowledge would improve the understanding and allow prediction of forest plant invasions and help prioritize actions for effective NNIPS control and mitigation.We used boosted regression trees and Bayesian non‐linear regression to analyse forest inventory data spanning 14 northern US states in combination with data on climate, land use and disturbance. Within each framework, we assessed the magnitude, direction and functional form of the effects of 18 regional to local environmental factors and their interactions on the probability of presence and richness of NNIPS in the forest understory, while controlling for sampling intensity, data collection time and spatial autocorrelation.The studied drivers together captured nearly 50% of the variation in NNIPS occurrence and richness and were sufficient to obtain sensible predictions. Most drivers exhibited monotonic non‐linear individual effects and several drivers showed non‐additive combined effects. Temperature and landscape openness were the two major determinants of NNIPS presence and richness, but their effects were to a different degree moderated by elevation, climatic and topographic wetness, and stand age. Stand age was a more important predictor of NNIPS invasion than stand productivity. Deer density tended to be positively associated with NNIPS, whereas gypsy moth outbreaks possibly have increased resistance to plant invasions.Synthesis and applications. To optimize non‐native invasive plant species (NNIPS) control efforts in forests, it is important to explicitly account for the functional form and interactions among the factors operating across spatial and temporal scales. Increasing the average stand age at the landscape and regional levels is essential for buffering against further invasions. Recurrent canopy disturbance likely slowed down NNIPS invasion previously, yet whether this holds under higher propagule pressure remains unknown. [ABSTRACT FROM AUTHOR]

Question: Do invasions by alien plant species with contrasting trait profiles (Arctotheca calendula, Carpobrotus spp., Conyza bonariensis and Opuntia dillenii) change the functional and phylogenetic structure of coastal plant communities? Location: Atlantic coastal habitats in Huelva (Spain). Methods: We identified species diversity and composition in 220 paired (invaded and non‐invaded) plots along the coast (440 plots in total). We measured nine functional traits for every native and invader species, namely, specific leaf area (SLA), specific root length (SRL), leaf and root dry mass content (LDMC and RDMC) and carbon isotope fraction (δ13C). We calculated, at the plot scale, community means (CMs) for each trait, functional richness, Faith's phylogenetic diversity and functional and phylogenetic mean pairwise dissimilarities. Results: Three out the four species showed rather extreme trait values compared to the native flora with greater impact on invaded communities. In plots invaded by A. calendula the values of the native communities of SLA and SRL increased, while LDMC, RDMC and δ13C decreased showing CMs more similar to its functional profile. Besides, these plots showed lower functional and phylogenetic diversity in the native component of the community. In plots invaded by Carpobrotus spp. and O. dillenii the CMs values for LDMC and δ13C increased, but have little effect on the functional and phylogenetic structure of the native communities, while no differences were observed for the communities invaded by C. bonariensis (the most functionally similar to the native species). Conclusions: Our study highlights that inferring community assembly rules from the exploration of functional and phylogenetic differences between invaded and non‐invaded plots is not straightforward. By considering invaders with different functional profiles, we have shown that species with different mechanisms of invasion have contrasting impacts on the community. Consequently, the effect of plant invaders differs depending on their functional distinction from the recipient community, rather than their phylogenetic origin. [ABSTRACT FROM AUTHOR]

Biological invasion poses a major threat to biodiversity and conservation efforts in protected areas. The Greater Shennongjia Area (GSA) is one of China's 16 key areas for biodiversity, as stated in the China National Biodiversity Conservation Strategy and Action Plan. However, the local authorities lack appropriate data on the extent and impact of exotic species in protected areas, as well as lack the capacity and motivation to properly plan for exotic species strategy and action plan to support both prevention, control as well as management of exotic plants in their jurisdiction. In addition, while most previous studies have focused on exotic species in protected areas, little effort has been devoted to specifying which environmental factors contribute to the difference between protected and non-protected areas. Here, we explored the current distribution pattern of the richness and abundance of exotic species in relation to environmental variables within the GSA. In total, we found 84 exotic plant species, of which 41 exotic species within the protected areas, in 64 genera and 27 families, predominately from Asteraceae, Fabaceae, and Poaceae. The generalized linear mixed models (GLMMs) revealed that the protection status and the distance to human settlements were the most important predictors of exotic plant richness and abundance in the GSA. Our results showed that the average exotic plant richness and coverage in the protected areas were 22% and 31% lower than outside the protected areas, respectively. Such differences were probably the result of anthropogenic activities (e.g., proximity to human settlements and the proportion of cropland). Although protected areas provide an important barrier against plant invasions, invasion may be a tricky issue for protected area management in the future. The Alliance of Protected areas in Western Hubei and Eastern Chongqing will need to further consider stringent control and management strategies for the entry of exotic species into protected areas to effectively maintain the continuity and integrity of the GSA's biodiversity and ecosystems. Our results provided guidance and support to enhance the capacity of scientific and effective management and sustainable development of the Shennongjia World Natural Heritage Site and other protected areas. • 41 exotic plants, 68.3% of which are invasive inside the protected areas in the GSA. • Protected areas are lower on the richness and abundance of exotic plants. • The less anthropogenic pressures in protected areas, the less exotic plants invasion. • Exotic plants are threatening the OUV of Shennongjia World Natural Heritage Site. • The Alliance of Protected Areas should proactively defend against exotic species. [ABSTRACT FROM AUTHOR]

India has numerous invasive alien plant species (IAPSs), which seriously impact biodiversity, ecosystem services, and economic development. The availability of reliable occurrence records of IAPSs is of great importance for their successful management, prediction of distribution across time and space, and other research and development efforts. Global databases of occurrence data, like the Global Biodiversity Information Facility (GBIF), are often not exhaustive, especially for India, and poorly represent the actual distribution of IAPSs in the country. Our objective in creating this data set was threefold: (1) to compile occurrence data for the invasive and naturalized alien plant species of India, (2) to collect spatial and temporal information associated with occurrence records, and (3) to share the data in an accessible format so every record is traceable to its sources and allow users to submit data to increase the resolution of the data set. To achieve these objectives, we extracted data from 3137 literature records and 357 herbarium sheets. For each occurrence record, we curated information for 20 variables, which were arranged in a table with the Darwin Core (DwC) terms as column names. All data were subjected to technical validation before being included in the database. A total of 12,347 occurrence records were obtained for 362 species (195 invasive aliens and 167 naturalized aliens). The number of collected occurrence records was much higher for the invasive aliens (73.7%) than for the naturalized alien species (26.3%). Our data set will supplement the GBIF data by 60.39%, and occurrence records will be added for 64 invasive and naturalized alien plant species. The data set, as a part of the larger database of the Indian Alien Flora Information (ILORA) database, is made available without any restrictions on use as long as this data paper is properly cited. We have also made provisions for users to submit occurrence‐related data following a data standard. The users are encouraged to cite the original reference when using a specific data record. The data set is expected to assist a wide range of stakeholders involved in India's scientific research, policy formulation, and decision‐making related to IAPSs. [ABSTRACT FROM AUTHOR]

Questions Many studies report a decrease of native species richness in communities after plant invasion by exotic taxa, but the implications of species losses on community functional structure and ecosystem processes have been less explored. The questions addressed are: (1) what are the impacts of invasive plant taxa on the functional structure of the recipient community; and (2) are there links between such functional structure and ecosystem properties representing key ecosystem processes? Location Costal habitats of Mallorca and Menorca, Balearic Islands, Spain. Methods In paired invaded and non-invaded plots, species frequencies and ecosystem properties related to biogeochemical cycles (soil C and N content, soil moisture and decomposition rate) were assessed. For every native species we obtained values of several functional traits (plant height, woodiness, N fixation and evergreenness). Then we calculated indices of community functional structure (community-weighted means for each trait; functional diversity: richness, evenness, divergence and dispersion; and functional redundancy) and compared them between paired invaded and non-invaded plots. The relationship with ecosystem properties was assessed using GLM. Results The spectra of trait distribution changed in the invaded assemblages towards a higher frequency of woodiness and evergreenness. Invaded communities showed decreased species richness, and lower functional richness, divergence, dispersion and redundancy. In contrast, ecosystem properties were scarcely sensitive to invasion. Functional redundancy was negatively related to soil N of invaded plots and soil moisture in the dry season, which suggests higher depletion of soil resources when several species share the same combination of trait values. Conclusions Carpobrotus invasion led to a functional homogenization within communities, which probably reduces their resilience. The functional structure of the community was more responsive to invasion than the ecosystem properties. The weak relationship between functional indices and ecosystem properties suggests that they may respond to invasion at different rates. [ABSTRACT FROM AUTHOR]

A definitive list of invasive species traits remains elusive, perhaps due to inconsistent ways of identifying invasive species. Invasive species are typically identified using one or more of four demographic criteria (local abundance, geographic range, environmental range, spread rate), referred to here as the demographic dimensions of invasiveness., In 112 studies comparing invasive and non-invasive plant traits, all 15 combinations of the four demographic dimensions were used to identify invasive species; 22% of studies identified invasive species solely by high abundance, while 25% ignored abundance., We used demographic data of 340 alien herbs classified as invasive or non-invasive in Victoria, Australia, to test whether the demographic dimensions are independent and which dimensions influence invasive species listing in practice., Species' abundances, spread rates and range sizes were independent. Relative abundance best explained the invasiveness classification. However, invasive and non-invasive species each spanned the full range of each demographic dimension, indicating that no dimension clearly separates invasive from non-invasive species., Graminoids with longer minimum residence times were more frequently classified as invasive, as were forbs occurring near edges of native vegetation fragments., Synthesis. Conflating multiple forms of invasiveness, by not distinguishing invasive species that are identified using different demographic criteria, may obscure traits possessed by particular subsets of invasive species. Traits promoting high abundance likely differ from those enabling fast spread and broad ranges. Examining traits linked with the four demographic dimensions of invasiveness will highlight species at risk of becoming dominant, spreading quickly or occupying large ranges. [ABSTRACT FROM AUTHOR]

Montane regions worldwide have experienced relatively low plant invasion rates, a trend attributed to increased climatic severity, low rates of disturbance, and reduced propagule pressure relative to lowlands. Manipulative experiments at elevations above the invasive range of non-native species can clarify the relative contributions of these mechanisms to montane invasion resistance, yet such experiments are rare. Furthermore, global climate change and land use changes are expected to cause decreases in snowpack and increases in disturbance by fire and forest thinning in montane forests. We examined the importance of these factors in limiting montane invasions using a field transplant experiment above the invasive range of two non-native lowland shrubs, Scotch broom ( Cytisus scoparius) and Spanish broom ( Spartium junceum), in the rain-snow transition zone of the Sierra Nevada of California. We tested the effects of canopy closure, prescribed fire, and winter snow depth on demographic transitions of each species. Establishment of both species was most likely at intermediate levels of canopy disturbance, but at this intermediate canopy level, snow depth had negative effects on winter survival of seedlings. We used matrix population models to show that an 86% reduction in winter snowfall would cause a 2.8-fold increase in population growth rates in Scotch broom and a 3.5-fold increase in Spanish broom. Fall prescribed fire increased germination rates, but decreased overall population growth rates by reducing plant survival. However, at longer fire return intervals, population recovery between fires is likely to keep growth rates high, especially under low snowpack conditions. Many treatment combinations had positive growth rates despite being above the current invasive range, indicating that propagule pressure, disturbance, and climate can all strongly affect plant invasions in montane regions. We conclude that projected reductions in winter snowpack and increases in forest disturbance are likely to increase the risk of invasion from lower elevations. [ABSTRACT FROM AUTHOR]

Landscape pattern might be an important determinant of non-native plant invasions because it encompasses components influencing the availability of non-native plant propagules and disturbance regimes. We aimed at exploring the relative role of patch and landscape characteristics, compared to those of habitat type and regional human influence on non-native plant species richness. For this purpose, we identified all non-native plant species in 295 patches of four coastal habitat types across three administrative regions in NE Spain differing in the degree of human influence. For each patch, we calculated several variables reflecting habitat patch geometry (size and shape), landscape composition (distribution of land-cover categories) and landscape configuration (arrangement of patches). The last two groups of variables were calculated at five different spatial extents. Landscape composition was by far the most important group of variables associated with non-native species richness. Natural areas close to diverse and urban landscapes had a high number of non-native species while surrounding agricultural areas could buffer this effect. Regional human influence was also strongly associated with non-native species richness while habitat type was the least important factor. Differences in sensitivity of landscape variables across spatial extents proved relevant, with 100 m being the most influential extent for most variables. These results suggest that landscape characteristics should be considered for performing explicit spatial risk analyses of plant invasions. Consequently, the management of invaded habitats should focus not only at the stand scale but also at the highly influential neighbouring landscape. Prior to incorporate landscape characteristics into management decisions, sensitivity analyses should be taken into account to avoid inconsistent variables. [ABSTRACT FROM AUTHOR]

Non-native plant invasions can lead to staggering ecological and economic costs. Thus, land managers are concerned about vectors of seed and propagule introduction onto public lands. Because horses are one of several potential vectors of non-native seed dispersal, we summarize and interpret existing literature and identify potential impacts of horse use on non-native plant spread in natural areas. Several studies indicate non-native seeds can germinate after digestion by horses. In addition to their ability to carry viable non-native seeds in their feces, the literature indicates horses can trample native vegetation, cause soil disturbance, and increase soil nitrogen availability in some habitats. The combination of disturbance, which is known to increase invasibility, and introduction of seeds in horse feces could promote non-native plant invasions in wildlands. However, in situ studies have not demonstrated direct causal links between horses and plant invasions. More research is required to determine where, and to what extent, establishment and spread of non-natives occurs in situ as a direct result of disturbances and seed introduction by horses. Guidelines or regulations regarding horse use already exist in some recreational areas. Where none exist, we recommend development of best management practices, such as weed education programs for equestrians, use of Certified Weed Free Feed, and placement of manure bunkers at horse camps and trailheads. [ABSTRACT FROM AUTHOR]

Invasive plants are typically managed using top-down control techniques that focus on the removal of the target organism. Bottom-up control limits the resources available to the undesired species by manipulating disturbance, competition, and successional processes, and thus may prevent reinvasion. Tamarisk species ( Tamarix sp.) have invaded riparian areas throughout western North America, resulting in expansive control efforts. A companion study has shown that a native competitor, Box elder ( Acer negundo), is capable of outcompeting and killing established Tamarisk through light interception in canyons of Dinosaur National Monument (DNM), Colorado. The goal of this study was to determine the feasibility of using Box elder as a bottom-up control agent by (1) determining the distributional overlap of the two species in DNM; (2) determining if Tamarisk facilitates Box elder establishment; and (3) analyzing Box elder seedling survival across a range of physical gradients. The distribution of Tamarisk and Box elder overlapped considerably throughout the study area. Box elder seedlings were planted under Tamarisk canopies or areas with the canopy removed. Survival was significantly higher under Tamarisk canopies, indicating that Tamarisk facilitates Box elder seedling survival. Box elder seedling survival was tested across soil texture, litter depth, groundwater depth, and shade intensities indicative of conditions found in the canyons of DNM, and survival was high for all treatments. The manipulation of competitive and successional processes through the promotion of Box elder and other native tree establishment is suggested as a means of bottom-up Tamarisk control to complement traditional control techniques. [ABSTRACT FROM AUTHOR]

Fire management practices affect alien plant invasions in diverse ways. I considered the impact of six fire management practices on alien invasions: fire suppression, forest fuel reduction, prescription burning in crown-fire ecosystems, fuel breaks, targeting of noxious aliens, and postfire rehabilitation. Most western United States forests have had fire successfully excluded for unnaturally long periods of time, and this appears to have favored the exclusion of alien plant species. Forest fuel reduction programs have the potential for greatly enhancing forest vulnerability to alien invasions. In part this is due to the focus on reestablishing pre-Euro-American fire regimes on a landscape that differs from pre-Euro-American landscapes in the abundance of aggressive non-native species. We may be forced to choose between restoring “natural” fire regimes or altering fire regimes to favor communities of native species. Intensive grazing in many western forests may exacerbate the alien problem after fire and temporally decoupling grazing and fire restoration may reduce the alien threat. Many shrubland ecosystems such as the Intermountain West sagebrush steppe or California chaparral have a natural, high-intensity crown fire regime that is less amenable to forest restoration tactics. Historical use of prescribed fire for type conversion of shrublands to more useful grazing lands has played some role in the massive annual grass invasion that threatens these shrublands. Fuel breaks pose a special invasive plant risk because they promote alien invasion along corridors into wildland areas. Use of prescription burning to eliminate noxious aliens has had questionable success, particularly when applied to disturbance-dependent annuals, and success is most likely when coupled with ecosystem restoration that alters the competitive balance between aliens and natives. Artificial seeding of alien species as a form of postfire stabilization appears to cause more problems than it solves and may even enhance alien invasion. [ABSTRACT FROM AUTHOR]

This paper identifies the historical precedents and recent advances in descriptive and analytical aspects of invasive plant ecology. The paper takes a global perspective that focuses primarily on natural and semi-natural systems. The dynamics of plant invasions depend on the unique combination of species and recipient environments in light of short-lived, but highly influential, stochastic events. Spreading from the original point of establishment can be virtually instantaneous or follow a prolonged timelag. Range extension proceeds according to a variety of patterns dependent on the interplay between dispersal modes and landscape characteristics. The impacts of plant invasions are all-encompassing: biodiversity loss, economic impacts and aesthetic impacts occasioned by the loss of traditional cultural or natural landscapes. From the conservation perspective, costs are incalculable, but undoubtedly high. The impacts of invasive plants on natural ecosystems occur across all levels of biotic organization and, in the worst case, result in global extinctions and modification of fundamental ecosystem properties that make restoration practically impossible. Plant invasions occur across all habitat types and have spawned complementary theories, which are briefly presented within particular contexts. [ABSTRACT FROM AUTHOR]

This dataset provides the Global Naturalized Alien Flora (GloNAF) database, version 1.2. GloNAF represents a data compendium on the occurrence and identity of naturalized alien vascular plant taxa across geographic regions (e.g. countries, states, provinces, districts, islands) around the globe. The dataset includes 13,939 taxa and covers 1,029 regions (including 381 islands). The dataset is based on 210 data sources. For each taxon‐by‐region combination, we provide information on whether the taxon is considered to be naturalized in the specific region (i.e. has established self‐sustaining populations in the wild). Non‐native taxa are marked as "alien", when it is not clear whether they are naturalized. To facilitate alignment with other plant databases, we provide for each taxon the name as given in the original data source and the standardized taxon and family names used by The Plant List Version 1.1 (http://www.theplantlist.org/). We provide an ESRI shapefile including polygons for each region and information on whether it is an island or a mainland region, the country and the Taxonomic Databases Working Group (TDWG) regions it is part of (TDWG levels 1–4). We also provide several variables that can be used to filter the data according to quality and completeness of alien taxon lists, which vary among the combinations of regions and data sources. A previous version of the GloNAF dataset (version 1.1) has already been used in several studies on, for example, historical spatial flows of taxa between continents and geographical patterns and determinants of naturalization across different taxonomic groups. We intend the updated and expanded GloNAF version presented here to be a global resource useful for studying plant invasions and changes in biodiversity from regional to global scales. We release these data into the public domain under a Creative Commons Zero license waiver (https://creativecommons.org/share-your-work/public-domain/cc0/). When you use the data in your publication, we request that you cite this data paper. If GloNAF is a major part of the data analyzed in your study, you should consider inviting the GloNAF core team (see Metadata S1: Originators in the Overall project description) as collaborators. If you plan to use the GloNAF dataset, we encourage you to contact the GloNAF core team to check whether there have been recent updates of the dataset, and whether similar analyses are already ongoing. [ABSTRACT FROM AUTHOR]