Introduction Of Invasive Plants Research Articles

Galápagos tortoise stable isotope ecology and the 1850s Floreana Island Chelonoidis niger niger extinction

A consequence of over 400 years of human exploitation of Galápagos tortoises (Chelonoidis niger ssp.) is the extinction of several subspecies and the decimation of others. As humans captured, killed, and/or removed tortoises for food, oil, museums, and zoos, they also colonized the archipelago resulting in the introduction of invasive plants, animals, and manipulated landscapes for farming, ranching, and infrastructure. Given current conservation and revitalization efforts for tortoises and their habitats, here we investigate nineteenth and twentieth century Galápagos tortoise dietary ecology using museum and archaeological specimens coupled with analysis of carbon (δ13Ccollagen and δ13Capatite), nitrogen (δ15N), hydrogen (δD) and oxygen (δ18Oapatite) stable isotopes and radiocarbon dating. We identify that Galápagos tortoise diets vary between and within islands over time, and that long-term anthropogenic impacts influenced change in tortoise stable isotope ecology by using 57 individual tortoises from 10 different subspecies collected between 1833 and 1967—a 134-year period. On lower elevation islands, which are often hotter and drier, tortoises tend to consume more C4 vegetation (cacti and grasses). Our research suggests human exploitation of tortoises and anthropogenic impacts on vegetation contributed to the extinction of the Floreana Island tortoise (C. n. niger) in the 1850s.

We don't know what we're missing: Evidence of a vastly undersampled invasive plant pool.

Invasive plants are a prominent threat to ecosystems and economies worldwide. Knowing the identity of invasive plants is critical for preventing their introduction and spread. Yet several lines of evidence, including spatial and taxonomic biases in reporting and the ongoing emergence of new invasives, suggest that we are missing basic information about the identity of invasive plants. Using a database of invasive plants reported in the peer-reviewed literature between 1959 and 2020, we examined trends in the accumulation of new invasive plants over time and estimated the size of the current pool of invasive plants both continentally and globally. The number of new invasive plants continues to increase exponentially over time, showing no sign of saturation, even in the best studied regions. Moreover, a sample-size based rarefaction-extrapolation curve of reported taxa suggests that what is documented in the current literature (3008 taxa) only captures 64% of the likely number of invasive plants globally (4721 taxa ± 132 SE). These estimates varied continentally; less than half of invasive plant taxa have likely been identified in Oceania and Central and South Americas. Studies that included multiple invasive plants (e.g., floristic studies) were much more efficient at adding new taxa to our global understanding of what is invasive (identifying 4.2 times more new taxa than single-taxon studies). With more potential invaders arriving every day, this analysis highlights a critical gap in our knowledge of the current invasive plant pool. Expanding invasion science to better encompass understudied geographic areas and increasing the numbers of floristic surveys would greatly improve our ability to accurately and efficiently identify what taxa are invasive. Preventing invasive plant introductions is incumbent upon knowing the identity of invasive plants. Thus, large knowledge gaps remain in invasion ecology that hinder efforts to proactively prevent and manage invasive plants.

Mislabelling may explain why some prohibited invasive aquatic plants are still being sold in Belgium

In Belgium, a voluntary code of conduct intended to prevent introduction of invasive plants through the horticultural trade has been implemented since 2009. European Regulation 1143/2014 that imposes legal bans on a number of plant taxa entered into force in 2015. However, studies regarding the presence of invasive plants in the Belgian horticultural trade remained scarce. In 2016–2017 and in 2020, we surveyed a total of 11 garden centres specialized in water gardening and compiled a list of 285 aquatic plant taxa that were being traded. In 2020, four Belgian Consensus List species and one Communication List species were still offered for sale. Also, three species of Union Concern were still being sold in 2020. The plants of the Belgian Lists that were still being sold in 2020 and all except one of the European Union List plants were mislabelled, either because of misidentification or because a taxonomic synonym was used. Mislabelling may explain why some prohibited plants were still in trade. Therefore, retailers and plant producers should be encouraged to correctly identify the plants that are being traded. Our study illustrates that regular surveys are essential to assess the effectiveness of voluntary codes of conduct and legal trade bans.

Performance of Danaini larvae is affected by both exotic host plants and abiotic conditions.

The consequences of the introduction of invasive plants for the diet of herbivorous insects have been little explored in nature where, potentially, abiotic and biotic factors operate. In this study, we examined the larval performance of two Neotropical Danaini butterflies when using either a native or an exotic Apocynaceae species as host plant in both field and laboratory experiments. Hosts greatly differ in their amount of latex exudation and other physicochemical traits, as well as in the amount of evolutionary time they have interacted with herbivores. First, herbivore performance on the hosts was investigated under laboratory conditions. Larvae of both Danaini species took more time to develop on the exotic host; larval survivorship did not vary between hosts. Second, first instar survivorship on both hosts was evaluated in two field sites, one site per host. To do so, in both sites half of the larvae were bagged (protected against both abiotic and biotic factors) while the remainder were nonbagged (exposed). The interaction between larval exposure with the use of the exotic host reduced larval survival. We concluded that the combined effects of host plant traits and abiotic factors reduced survival of herbivores in field conditions. Therefore, the performance of herbivores when using hosts of different origins should be considered together with the multiple ecological factors found in natural environments, as these factors can modify the result of plant–herbivore interactions.

Color of Pan Trap Influences Sampling of Bees in Livestock Pasture Ecosystem.

Simple SummaryPollination is important for fertilization, setting fruits, seed development and the continuation of the life cycle of plants that eventually provide food for humans, livestock and wildlife. Agronomic practices, use of pesticides, lack of diverse flowering plant species, introduction of invasive plants, loss of habitat, climate change and disease have all led to the decline of important pollinator species. Decline of insect pollinators has increased the importance of accurately monitoring pollinator diversity and abundance over time. Sampling techniques using different color traps are used to sample bees and other insects, but their utility and effectiveness in different ecosystems still need to be determined. In this study, we examined four different colors of pan traps (blue, green, yellow, and purple) for their utility in sampling bees in a livestock pasture ecosystem consisting of native forage species. We analyzed the relative abundance, richness, similarity, and community assemblage patterns associated with aforementioned colors. We found that the blue color traps were the most attractive to bees and were effective for sampling bees in a livestock pasture ecosystem. Purple color traps were the second most effective, followed by yellow and green color traps.The decline in insect pollinators has increased the importance of accurately monitoring pollinator diversity and abundance over time. Sampling techniques include the use of passive insect traps such as pan traps, yet there is still discussion over their utility and effectiveness in different ecosystems. The objective was to examine four different colors of pan traps (blue, green, yellow, and purple) for their utility in sampling bees in native forages rotationally grazed by sheep and to compare the relative abundance, richness, similarity, and community assemblage patterns among the four trap colors. Most bees were from the Halictidae family (89%). The most abundant species were Lasioglossum imitatum (42.2%), Augochlorella aurata (8.3%), L. subviridatum (6.8), Agapostemon texanus (6.4), and L. birkmani (4.1%). Blue color traps exhibited the highest rates of bee capture and species accumulation. Purple and yellow colored traps were moderately effective in capturing bees, while the green color pan traps were least effective. Similarly, observed and extrapolated species richness was highest in blue trap, followed by purple, yellow, and green. Notably, the blue trap captured the highest number of unique species, followed by purple, yellow and green traps. Considering the total number of insects collected (including bees and other insects), yellow and green traps captured a significantly higher number of insects than other colored traps. The light reflectance from blue, purple, green and yellow pan traps had peaks at ~450, 400, 550, and 600 nm, respectively. Since different insects respond to different light intensities, wavelengths, and reflectivity, these results could be used to guide future trapping protocols targeting certain insect groups in livestock pasture and similar ecosystems.

People's Knowledge and Risk Perceptions of Invasive Plants in Metro Vancouver, British Columbia, Canada.

Effective management of invasive plants conserves biodiversity values, reduces economic costs, and minimizes negative impacts on human health. Fostering people's awareness of invasive plants is one of the most cost-effective approaches in preventing the spread and introduction of invasive plants. Therefore, this study aims to understand (1) people's knowledge and risk perceptions, (2) associations between risk perceptions and demographics, and (3) people's willingness to support current management strategies in the Metro Vancouver region, British Columbia, Canada. An online survey was carried out and received 356 responses across the region. We found that people's knowledge and risk perceptions of invasive plants were ecologically oriented. Older respondents perceived higher risks of invasive plants. Among respondents of the same age, annual income higher than $50,000 was associated with higher levels of risk perception. Respondents who had professional and/or recreational group memberships perceived higher economic risks. Respondents highly supported activities that they could take part in directly, such as community invasive pulls and native species planting. Overall, our findings aid managers in allocating appropriate funding or tailoring outreach efforts to different aspects of invasive plants as well as groups/communities where people's knowledge and risk perceptions of invasive plants are low.

ANALISIS KEBIJAKAN PENYEDIAAN LAHAN BAGI PEMBANGUNAN DENGAN KEWAJIBAN PENANGGULANGAN DAN PENCEGAHAN DINAMIKA TUMBUHAN INVASIF DI INDONESIA

Life on land as one of the goals of sustainable development is an important aspect to be realized. Terrestrial ecosystems become a space for human life to carry out their daily activities. However, the high activity of trade, tourism, and development risk of degradation of terrestrial ecosystems is increasing. The introduction of invasive plants as a result of its aspects currently ranks second as the cause of loss of organism species under the main cause of land conversion. This study aims to analyze development policies in terms of handling invasive plants in Indonesia. The study was conducted with literature reviews and desk study through a review of laws, government regulations, presidential decrees, and ministerial regulations. Based on the results, it is known that basically, Indonesia does not yet have policies that regulate in detail and detail about invasive alien plants, existing policies only regulate the management and protection of biodiversity. There are 9 documents relating to biodiversity conservation, but no one of these policy documents has touched on clearly and in detail about protecting ecosystems from the threat of invasive alien species. Policies need to be established regarding principle licenses, location permits, business licenses, and trade access permit to suppress and minimize the spread of invasive plants. The thing that needs to be emphasized is the clarity of the policy (legislation) because only through this strategic steps can be done on a clear and strong legal basis.

Metal Contamination Hotspots in the Everglades

Left: shell casings at a site in the Everglades. Top right: Megan Bruce operating an atomic absorption flame emission spectrophotometer. Bottom right: J. Matt Hoch and Bruce collecting samples at a site in the Everglades. The Everglades ecosystem of South Florida may appear to be a wild, untouched landscape. However, there is a long history of human impacts—from attempts to drain the river of grass in the 1920s to pollution from agricultural and urban development and the introduction of invasive plants and animals. Currently, there are large-scale efforts to restore water flow and habitat in this unique ecosystem, but human impacts—both small and large—are still apparent. J. Matthew Hoch, Associate Professor in the Department of Marine and Environmental Sciences at Nova Southeastern University, conducts research in the Everglades. He says that during outings with a field course, the group noticed areas that are illegally used for firearm target practice. These unregulated illegal shooting ranges are littered with bullet casings and other trash. Hoch and his students wondered if these shooting ranges were contaminated with metal—from the soil and water to the plants and animals—and Hoch and co-author Megan Bruce decided to investigate further. The results of this initial survey were recently published in the Journal of Environmental Quality (https://doi.org/10.2134/jeq2018.08.0319). In 2017, Hoch and colleagues took survey samples at sites in the Everglades ecosystem. They sampled water, sediment, plants, and invertebrates and tested for lead, copper, and aluminum. Samples were collected at two unregulated shooting sites, three reference sites in the Everglades that did not show evidence of ammunition accumulation, and at a regulated shooting range. The samples revealed that the unregulated shooting areas are contaminated by copper and lead. The levels of lead and copper in the sediment at the unregulated sites were greater than the reference sites and similar to the levels found at the regulated shooting range. Lead levels in plants were also greater at the unregulated sites compared with the reference sites. Additionally, the average lead levels in grass shrimp at target sites was 416.1 µg/g compared with levels averaging 18.9 µg/g at the reference sites. This initial work documents the contamination associated with these unregulated target practice areas and leads to new questions. Hoch and his lab recently obtained grant funding to purchase new equipment that will enable them to do more in-depth analyses. He would like to do a more detailed sampling of plants and animals to test for bioaccumulation of lead and copper in the food chain that may originate at these sites. Understanding how these metals move through the ecosystem is important considering the Everglades ecosystem is critical habitat for many threatened and endangered species, including the Florida panther, American crocodile, wood stork, and snail kite. The problems with illegal firearm use go beyond contamination as these areas can pose a risk to other people using public lands who are unaware of the existence or exact location of these illicit shooting ranges. For example, Hoch described how during this study, a fisherman was accidentally killed by target shooters at one of the study sites. In the western U.S., target shooters have also started wildfires on public land, resulting in damage to structures and costly firefighting efforts. View the Journal of Environmental Quality article, “Metal Contamination Hotspots at Unregulated Firearm Target Shooting Sites in the Everglades” at: https://doi.org/10.2134/jeq2018.08.0319. It will likely take a combination of efforts, including education and increased law enforcement, to reduce illegal target practice on public land in the Everglades and on other sites across the U.S. Increasing law enforcement presence can be expensive, but it is probably the most effective strategy. After the shooting accident mentioned earlier, Hoch says a law enforcement agent was stationed near the target shooting site. This resulted in a decrease in target shooting at the site and suggests that increased law enforcement presence can reduce these activities on public land.

Changes in vegetation cover on the Younghusband Peninsula transgressive dunefields (Australia) 1949–2017

AbstractStudies have shown that the impact of climate change, human and animal actions on coastal vegetation can turn stabilized dunes into active mobile dunes and vice versa. Yet, the driving factors that trigger vegetation changes in coastal dunes are still not fully understood. In the transgressive dunefields of the Younghusband Peninsula (south‐east coast of South Australia) historical aerial photographs show an increase in vegetation cover over the last ~70 years. This study attempts to identify the causes of the changes in vegetation cover (1949 to 2017) observed in a typical section of the coastal dune systems of the Peninsula. Vegetation cover was first estimated for various years using the available historical aerial photography (long‐term changes – 1949 to 2017) and recent satellite imagery (short‐term annual changes – 2010 to 2017) for the area, and then results were discussed against the observed changes in climatic variables and rabbit density, factors that could have played a role in this transformation. Results of long‐term changes show that the vegetation cover has increased significantly from 1949 to 2017, from less than 7% vegetation cover to almost 40%, increasing dune stabilization and forming parabolic dune systems. Periods with the largest growth in vegetation cover (1952‐1956 and 2009‐2013) coincide with a significant decline in rabbit numbers. Rabbit density was found to be the primary factor linked to the rapid vegetation growth and stabilization of the dunefield, for both decadal long‐term (last 68 years) and annual short‐term changes (last 8 years). Other factors such as changes in rainfall, aeolian sediment transport, land use practices, and the introduction of invasive plants have apparently played a limited to negligible role in this stabilization process. © 2018 John Wiley & Sons, Ltd.

Woody plant invasions into the Upper Volga natural communities

The questions of woody invasive plant introductions into natural communities of the Upper Volga region are considered. It is established that, of 798 alien species of the region, 119 (14.9%) are woody plants, 27 tree and shrub species successfully naturalized and intruded into natural communities of various degrees of disturbance, and 7 species are included in the Black Book of Central Part of European Russia. The majority of invasive woody plants are species of Northern American origin. Examples of invasive woody species introduced into plant communities of the region, including the specially protected natural territories, are given.

Effecting compliance with invasive species regulations through outreach and education of live plant retailers

Movement of organisms through the horticultural trade explains the majority of nonindigenous aquatic invasive plant introductions. Prevention is the most promising approach to reducing the spread of nonindigenous species, but key vectors persist. To better understand the risk posed by trade in aquatic plants, we surveyed all known aquatic plant retail locations in Wisconsin and quantified the prevalence of nonindigenous species in retail stock. We conducted an educational program that utilized in-person educational visits and mailed informational packets to inform vendors of existing regulations, increase accuracy of species identification, and create awareness of best management practices. We compared the change in prevalence of regulated nonindigenous species in trade following education. Educational visits and mailed informational packets were both associated with a decrease in the number of nonindigenous species available for sale. However, in-person education increased vendor compliance more than a single informational mailing. We observed an initial noncompliance rate of 51 % but even after education, 27 % of stores remained noncompliant. Our results suggest that education can improve compliance with invasive species regulations, but additional steps may be necessary to further reduce the rate of noncompliance.

Do native and invasive labels affect consumer willingness to pay for plants? Evidence from experimental auctions

AbstractOrnamental plant sales have been identified as an important vector for the introduction of invasive plants. Increased concerns about the economic and ecological costs of invasive plants have spawned interest in identifying strategies to curtail introductions. One possible strategy is labeling plants based on whether they are invasive or native. The primary purpose of this paper was to explore how labeling plants based on invasive and native attributes might affect consumer demand. To accomplish this objective, a second price auction was used to elicit the willingness to pay (WTP) for plants with and without labels. On average, we found a $0.35 premium for plants labeled as noninvasive and native and a $1.01 to $1.66 discount for plants labeled as invasive. The size of these premiums and discounts differed in relation to various demographic, attitudinal, and preference‐related factors. Overall, our results suggest that labeling plants as invasive or native could be a viable strategy for reducing the introduction of invasive plants.

A Conceptual Framework for Preventing the Spatial Dispersal of Invasive Plants

Invasive plant species have adversely affected rangelands throughout the world and continue to invade previously uninfested lands at an alarming rate. Previous efforts have focused on eradication and control; however, recent efforts have recognized that preventing invasive plant species from infesting new areas is more cost-effective and efficient than trying to restore the system after it is infested. One of the major components of prevention is limiting the introduction of the invasive plant to uninfested areas. Guidelines to limit the introduction of invasive plants into new areas are usually general and not developed to address differences in dispersal vectors among invasive plants. To limit the dispersal of invasive plants, land managers need a framework that assists them in identifying major spatial dispersal vectors and management strategies based on those vectors. We propose an initial conceptual framework that integrates the ecology of invasive plant dispersal with prevention management. The framework identifies major potential vectors by incorporating invasive plant seed adaptations for dispersal through space and infestation locations relative to vector pathways. The framework then proposes management strategies designed to limit dispersal by those specific vectors. The framework ALSo identifies areas where research could improve the effectiveness of dispersal-prevention strategies by providing additional management tools.

Preventing horticultural introductions of invasive plants: potential efficacy of voluntary initiatives

Although prevention is the most cost- effective way to avoid the enormous expenses associated with plant invasions, invasive plants continue to be imported as trade commodities for horticultural use. With very little government regulation of horticultural imports of invasive plants, efforts have turned toward fostering volun- tary initiatives to encourage self-regulation by the horticulture trade. Our study takes the first step toward evaluating the potential success of these voluntary initiatives. We conducted a survey of nursery professionals to gauge their perceptions of invasive species, the role of the horticulture trade in invasive plant introductions, and their participa- tion—potential and actual—in preventive mea- sures outlined in the St Louis Voluntary Codes of Conduct for nursery professionals. We found nurs- ery professionals to be highly aware of invasive plants and to accept responsibility as a trade for horticultural introductions. Although only 7% of respondents had heard of the St Louis Voluntary Codes of Conduct, the majority (57%) reported having participated in at least two of seven preventive measures, and most (78%) reported willingness to engage in the majority of preventive measures. We found that several factors signifi- cantly predict increased participation in preventive measures, particularly awareness of invasive plants and involvement in trade associations. We also identified incentives and obstacles to participating in preventive behaviors, including ''concern for the environment'' and ''lack of information,'' respec- tively. Our results suggest that participation in voluntary initiatives will improve through increased outreach, and we provide specific recommenda- tions for improving participation in voluntary programs in the horticulture trade.

Predicting invasions by woody species in a temperate zone: a test of three risk assessment schemes in the Czech Republic (Central Europe)

ABSTRACTTo assess the validity of previously developed risk assessment schemes in the conditions of Central Europe, we tested (1) Australian weed risk assessment scheme (WRA; Pheloung et al. 1999); (2) WRA with additional analysis by Daehler et al. (2004); and (3) decision tree scheme of Reichard and Hamilton (1997) developed in North America, on a data set of 180 alien woody species commonly planted in the Czech Republic. This list included 17 invasive species, 9 naturalized but non‐invasive, 31 casual aliens, and 123 species not reported to escape from cultivation. The WRA model with additional analysis provided best results, rejecting 100% of invasive species, accepting 83.8% of non‐invasive, and recommending further 13.0% for additional analysis. Overall accuracy of the WRA model with additional analysis was 85.5%, higher than that of the basic WRA scheme (67.9%) and the Reichard–Hamilton model (61.6%). Only the Reichard–Hamilton scheme accepted some invaders. The probability that an accepted species will become an invader was zero for both WRA models and 3.2% for the Reichard–Hamilton model. The probability that a rejected species would have been an invader was 77.3% for both WRA models and 24.0% for the Reichard–Hamilton model. It is concluded that the WRA model, especially with additional analysis, appears to be a promising template for building a widely applicable system for screening out invasive plant introductions.

Natural and land-use history of the Northwest mountain ecoregions (USA) in relation to patterns of plant invasions

Although the Northwest currently has the least proportion of non-native invasive plant species relative to other regions of North America, invasions continue to increase into the mountainous areas of the region. Landscape structure, such as the variation found along the complex gradients of the Northwest mountain ecoregions, affects the expansion of invasive plant species and the invasibility of plant communities. Also, the history of land use and current use patterns affect the expansion of invasive plants, and many of the deteriorated environments in the region's mountains may invite and stabilize plant invasions. We examined the patterns of invasive plant diversity in Northwest mountain ecoregions, as derived from literature sources, to analyze which factors influence plant invasions. Our analysis found altered riparian systems and disturbed forests to be especially vulnerable to plant invasion. Conversely, alpine and wilderness areas are still relatively unaffected by invasive plants. Both riparian and alpine communities, while making up a relatively small area across Northwest mountain ecoregions, have significant ecological importance and deserve special protection from invasive plant introductions. Human settlement at low elevations and intense land use of upland forests will likely continue to enhance invasive plant introductions into Northwest mountain ecosystems. Knowledge of the relationships between biological and environmental factors, disturbance, and human land use will be critical for future management strategies that proactively locate, prevent, or contain plant invasions in the mountains of the Northwest.

The late Quaternary extinction and future resurrection of birds on Pacific islands

People have lived on tropical Pacific islands over the past 30,000 years (Bismarcks, Solomons) or 3000 to 1000 years (the rest of Oceania). Their activities have led to the loss of many thousands of populations and as many as 2000 species of birds that probably otherwise would exist today. This extinction event is documented by avian fossils from archaeological (cultural) and paleontological (noncultural) sites from nearly 70 islands in 19 island groups. Extinction of birds in Oceania rivals the late Pleistocene loss of large mammals in North America as the best substantiated rapid extinction episode in the vertebrate fossil record. Some avian extinctions in Oceania occurred within a century or less after human arrival, while others required millennia or even tens of millennia. Any of these time frames is rapid in an evolutionary or geochronological sense. Inter-island differences in the speed and extent of extinction can be explained by variation in abiotic (A), biotic (B), and cultural (C) factors. Levels of extinction on large, near islands can be comparable to those on small, remote islands when C factors (such as high human population density and introduction of invasive plants and animals) override A factors (such as large land area or little isolation) or B factors (such as rich indigenous floras and faunas). An innovative, proactive conservation strategy is needed not only to prevent further extinctions of birds in Oceania, but also to restart evolution of some of the lineages that have suffered the most loss, such as flightless rails. This strategy should focus on islands with ABC traits that retard rather than enhance extinction.

Horticulture as a Pathway of Invasive Plant Introductions in the United States

Abstract There must have been plenty of them about, growing up quietly and inoffensively, with nobody taking any particular notice of them…. And so the one in our garden continued its growth peacefully, as did thousands like it in neglected spots all over the world…. It was some little time later that the first one picked up its roots and walked. John Wyndham, The Day of the Triffids

Predicting Invasive Plants: Prospects for a General Screening System Based on Current Regional Models

Screening systems for predicting invasive plants have been independently developed for the non-indigenous floras of North America, the South African fynbos, and Australia. To evaluate the performance of these screening systems outside the regions for which they were developed, we tested them for the non-indigenous flora of the Hawaiian Islands. When known invasive plant species in the Hawaiian Islands were evaluated using the North American and Australian systems, 82% and 93% of the species were predicted to be invasive, respectively, and the remainder were classified as requiring further study. The South African fynbos system correctly predicted only 60% of the invasive species in the Hawaiian Islands. All three screening systems correctly classified a majority of the non-invaders as non-invasive. The Australian system has several advantages over the other systems, including the highest level of correct identification of invaders (>90%), ability to evaluate non-woody plants, and ability to evaluate a species even when the answers to some questions are unknown. Nevertheless, with the Australian system, a large fraction of species known not to be invasive were recommended for further study before importing, so there remains room for improvement in identifying non-invasive species. Based on our results for the Hawaiian Islands and a previous evaluation in New Zealand, the Australian system appears to be a promising template for building a globally applicable system for screening out invasive plant introductions.