Non-native Invasive Plant Species Research Articles

Multi-Year Monitoring of Asclepias syriaca L. Spread in the Deliblato Sands Protected Reserve in Serbia

The invasion of non-native plant species has a detrimental effect on native biodiversity. In a seven-year research project, we investigated the occurrence of the invasive species Asclepias syriaca L.in the Deliblato Sands protected area, located at a south-eastern part of the Pannonian Plain, and identified the factors that contribute significantly to its colonisation. The distribution of this invasive species was monitored on more than 300 km of the accessory, bordering and selected internal roads. A. syriaca occurs within the protected area but is much more widespread on accessory and bordering roads. The number of locations of A. syriaca increased every year of the study, even within the protected area, indicating a further spread of this species. A. syriaca is much more abundant on the north-eastern edge than in the south-west. The reason for this is most likely the much larger area of abandoned agricultural land in the north-east. Roads used for public transport are the main entry points for the further spread of A. syriaca. In contrast, recreational trail use does not enhance the spread in the Deliblato Sands natural reserve. This study can be used to further analyse the ecological dynamics of A. syriaca and to develop timely strategies by which to prevent or slow down its spread.

Determining spatial units for modeling regional nonnative invasive plant species spread in the southern US forestlands: using the state of Alabama as an example

Determining spatial units for modeling regional nonnative invasive plant species spread in the southern US forestlands: using the state of Alabama as an example

Collating existing evidence on cumulative impacts of invasive plant species in riparian ecosystems of British Columbia, Canada: a systematic map protocol

BackgroundGlobally, the structure and functioning of foreshore and riparian ecosystems are being dramatically impacted by non-native invasive plant species. Invasive species can outcompete and replace native species, modify geochemical and hydraulic cycles, alter trophic processes, and change the composition and structure of communities above and below ground. However, these impacts are often investigated in isolation, even though one invasive species might increase or mitigate the impacts of others (i.e. cumulative impacts), potentially with cascading effects. Although cumulative impacts have long been studied within other environmental contexts, research on the cumulative impacts of invasive species is comparatively scarce. We aim to develop a protocol to systematically identify and collate evidence on the individual and cumulative impacts of a set of plant species invasive in foreshore and riparian ecosystems of British Columbia, Canada. Our primary question is: what evidence is available on the individual and cumulative impacts of invasive plants in the riparian and foreshore ecosystems of British Columbia, Canada? In addition, our systematic map will identify the strengths and gaps in knowledge pertaining to invasive plant species impacts in foreshore and riparian ecosystems, with the ultimate goal of facilitating the development of evidence-based management strategies.MethodsWe identified the research topic and the primary and secondary questions with the support of stakeholders. We then devised a flexible string that allows for searching target invasive species. Using this string, we searched the literature for pilot species that aided the iterative development of the protocol. Once all target species are identified, we will carry out a systematic literature search on their impacts. We will search Web of Science and the CABI compendium for invasive species. We will include studies if they (i) refer to the target invasive species, (ii) focus on its environmental impacts and (iii) investigate such impacts in riparian ecosystems (iv) within North America (i.e. Canada and U.S.A.). We will use a two-stage screening process: titles and abstracts first, then the full manuscript. From each source, we will extract impact description, ecosystem component impacted, and magnitude and directionality of impacts. We will include a publicly available database of studies, descriptive statistics, and a narrative summary within our synthesis outcomes.

Soil microbes mediate the effects of resource variability on plant invasion.

A fundamental question in ecology is which species will prevail over others amid changes in both environmental mean conditions and their variability. Although the widely accepted fluctuating resource hypothesis predicts that increases in mean resource availability and variability therein will promote nonnative plant invasion, it remains unclear to what extent these effects might be mediated by soil microbes. We grew eight invasive nonnative plant species as target plants in pot-mesocosms planted with five different synthetic native communities as competitors, and assigned them to eight combinations of two nutrient-fluctuation (constant vs. pulsed), two nutrient-availability (low vs. high) and two soil-microbe (living vs. sterilized) treatments. We found that when plants grew in sterilized soil, nutrient fluctuation promoted the dominance of nonnative plants under overall low nutrient availability, whereas the nutrient fluctuation had minimal effect under high nutrient availability. In contrast, when plants grew in living soil, nutrient fluctuation promoted the dominance of nonnative plants under high nutrient availability rather than under low nutrient availability. Analysis of the soil microbial community suggests that this might reflect that nutrient fluctuation strongly increased the relative abundance of the most dominant pathogenic fungal family or genus under high nutrient availability, while decreasing it under low nutrient availability. Our findings are the first to indicate that besides its direct effect, environmental variability could also indirectly affect plant invasion via changes in soil microbial communities.

Predicting vulnerability of forest patches to invasion by non-native plants for landscape scale management.

As a leading cause of forest health degradation, non-native invasive plant species are a key focus for many forest management and conservation efforts. These efforts come at a high price for resource limited agencies and organizations making cost effectiveness an important objective of invasion response plans. In this paper we present an approach to guide the prioritization of locations for invasion management using species distribution models that account for the non-equilibrium of invasive species distributions and use readily available land use data as the primary explanatory variables. This approach takes advantage of the relatively high spatial resolution, as well as the broad, continuous geographic coverage, of land use data to provide results at a landscape scale relevant to practitioners responsible for invasive species management. In our example from northern Virginia, we simultaneously modeled a suite of invasive plant species to identify common indicators of invasion. We found that the proportions of surrounding non-forested land use types (grasses, crops, and development) were the most common and strongest indicators of invasion risk. These outcomes can guide managers of large protected areas to focus on major divides between forest and non-forest land over linear disturbances. We also found useful species-specific traits that can inform specific management actions. Additionally, we demonstrate through a case study how organizations that manage multiple smaller properties can take advantage of the projected distribution maps when considering acquiring or administering properties.

The peroxidase response of Alternanthera philoxeroides (Alligator Weed) and Nasturtium officinale (Watercress) to heavy metal exposure.

We examined the effects of copper and lead on the antioxidant enzyme response of Alternanthera philoxeroides and Nasturtium officinale using a benchtop luminometer. Alternanthera philoxeroides is a nonnative invasive plant species that has spread throughout the wetland ecosystem in the southern part of the USA. Its invasion is facilitated by its ability to thrive in a wide range of abiotic conditions. Nasturtium officinale is an aquatic plant that is sensitive to relatively low amounts of pollution and is most commonly found in springs and shallow bodies of water. While A. philoxeroides tolerates organic pollution and heavy metals, N. officinale exhibits stress at low levels of pollution. Alternanthera philoxeroides antioxidant enzyme production was unaffected by increasing concentrations of both copper and lead. The antioxidant enzyme response of N. officinale showed a significant increase when plants were exposed to 10 and 25ppm lead. Endogenous peroxidase concentrations of the control plants were also compared showing that A. philoxeroides possessed a significantly higher concentration of peroxidases than N. officinale. We hypothesize that a higher endogenous peroxidase concentration may be a mechanism that hyperaccumulator plants use to tolerate inhospitable concentrations of copper and lead.

Competition effect exerted by two nonnative invasive plant species on a native under contrasting conditions of resource availability

Competition effect exerted by two nonnative invasive plant species on a native under contrasting conditions of resource availability

Interactions between tall oatgrass invasion and soil nitrogen cycling

Increases in nitrogen (N) inputs to the biosphere can exacerbate the introduction and spread of invasive non-native plant species. Often, with elevated soil N levels, invasive plants establish and further enrich soil N pools, changing overall ecosystem function. This study examined the relationship between soil N cycling and an increasingly prevalent, invasive plant species, tall oatgrass (Arrhenatherum elatius subsp. elatius), in foothills ecosystems between the Colorado Rocky Mountains and the Denver-Boulder Metropolitan area—similar to many Western US grasslands and woodlands. It focused on investigating differences in soil N transformations, inorganic N pools, and vegetation characteristics across invaded and uninvaded plots at three sites in two seasons (summer and autumn). There was a statistically significant effect of invasion on rates of net N mineralization, but it was dependent on site and season (p = 0.046). Site had a statistically significant effect on soil moisture and aboveground biomass C:N (p < 0.04). The interactions of invasion x site were statistically significant for ammonium pools (p < 0.03). These findings suggest that A. elatius invasion can be associated with accelerated N cycling, but that the nature of the relationship differs by location and season in the foothills. More broadly, this study contributes to determining how the N cycle is shifting in grassland ecosystems subject to increasing pressures from anthropogenic change.

Comparison of Plant Trait Biometrics for Paired Invasive and Non-Invasive Species to Magnetized Seed and Watering Treatments

A greenhouse study evaluated the widely held hypothesis that invasive plant species have a quicker or stronger response to environmental stimuli such as magnetized irrigation water treatments. A second study objective was to test whether the polarity of magnetized water affected the responses for invasive and non-invasive plant species. Six invasive and six non-invasive plant species were stimulated by magnetizing the seeds followed by applying several magnetized water treatments to the germinated seeds. The species were taxonomically paired then the seeds were exposed to three magnetic field treatments, planted, and irrigated with three magnetized water treatments for approximately two months. The electrical conductivity, oxidation reduction potential (ORP), pH of the water, and nine plant biometrics were measured, collected, and analyzed. The study hypothesis was validated when the invasive species showed enhanced responses to the magnetized seed and water treatments. The invasive species had increased growth in seven out of the nine growth biometrics when exposed to the magnetized seed and water treatments. The long exposure time for pretreatment of seeds (six days) and extended exposure time of the water treatments on the magnets (20 h) contributed to the higher growth rates. The average increase in foliar biomass and leaf area for two paired, invasive species was 184 and 182%, respectively, for the combined seed/watering treatments. In comparison the average increase in foliar biomass and leaf area for two paired, non-invasive species was 88 and 111%, respectively, for the combined seed/watering treatments. The physicochemical water properties for the three magnetized water treatments were correlated with plant growth. The combined magnetic seed/watering treatments produced growth rates that substantially exceeded crop growth rates in comparable magnetized irrigation studies.

Spatiotemporal Invasion Severity of Chinese Tallow (Triadica sebifera) and Invasibility of Forest Types in Southern US Forestlands

Abstract Quantifying invasion severity of nonnative invasive plant species is vital for the development of appropriate mitigation and control measures. We examined more than 23,250 Forest Inventory and Analysis (FIA) plots from the southern coastal states of the United States to develop an alternative method to classify and map the invasion severity of Chinese tallow (Triadica sebifera). Remeasured FIA plot-level data were used to examine the spatiotemporal changes in the presence probability and cover percentage of tallow. Four invasion severity classes were identified by using the product of presence probability and cover percentage. Chinese tallow invasion severity increased over time with 90 and 123 counties being classified into the highest severity class for the first and second measurement, respectively. Further, the invasibility of major forest-type groups by severity class was examined using the product of the county-level mean presence probability and mean cover percentage of Chinese tallow as a proxy of invasibility. Longleaf/slash pine (Pinus palustris/P. elliottii) forests were highly resilient to the Chinese tallow invasion. In contrast, elm/ash/cottonwood (Ulmus spp./Fraxinus spp./Populus deltoides) and oak/gum/cypress (Quercus spp./Nyssa spp./Taxodium spp.) forest-type groups were vulnerable to invasion.

Development and resilience of deciduous Nothofagus forests since the Last Glacial Termination and deglaciation of the central Patagonian Andes

Resolving the history of vegetation, fire, and glaciation on the eastern slope of the central Patagonian Andes (44°-49°S) since the Last Glacial Termination (T1) has proved difficult. This is due to the steep environmental gradients, vegetation heterogeneity, and scarcity of dated glacial deposits and geomorphic features. Unsurprisingly, published records show important heterogeneities which limit our understanding of the timing and magnitude of climate and vegetation changes, and their driving mechanisms since T1. In this paper, we describe sediment cores from small closed-basin lakes located in the deciduous Nothofagus forest zone near Coyhaique, Chile. Our results indicate that the Coyhaique glacier lobe abandoned its final Last Glacial Maximum position just before ~17.9 cal kyr BP and underwent a step-wise recession that included a halt/readvance that culminated at ~16.8 cal kyr BP, contemporaneous with the formation of an ice-dammed proglacial lake in the Coyhaique/Balmaceda sector. This glacial lake stood at its highest level between ~17.9–17.2 cal kyr BP (<726 and > 650 m.a.s.l.), lowered between ~17.2–16.2 cal kyr BP (<650 and > 570 m.a.s.l.), and disappeared thereafter. Herbs and shrubs, currently dominant in high Andean and Patagonian steppe environments, colonized the ice-free terrains distal to the glacier margins and proglacial lakes under cold and dry conditions. This was followed by a steady increase in Nothofagus between ~16.6–14.8 cal kyr BP that led to the establishment of forests starting at ~14.8 cal kyr BP. The Holocene started with a sudden increase in Nothofagus and disappearance of conifers in the context of increase fire activity between ~11.7–9.4 cal kyr BP. Closed-canopy Nothofagus forests persisted virtually unaltered from ~9.4 cal kyr BP to the present day, despite frequent explosive volcanism and millennial-scale variations in fire regimes, attesting to their extraordinary postglacial resilience which contrasts with their behavior during T1. Recent large-scale deforestation by fire, livestock grazing, and the spread of non-native invasive plant species drove the fastest and largest-magnitude shifts seen during the last ~16,500 years.

Determination of heavy metals in the territory of contaminated areas of Greece and their restoration through hyperaccumulators

Phytoremediation is an effective technique for the processing of contaminated soil and for sequestering environmental contaminants such as heavy metals. This kind of pollution is ubiquitous in mines and similar excavation sites. This mini-review aims to provide an overview of the alternative forms of restoring contaminated soils (phytoremediation) highlighting the areas of Kozani (Agios Dimitrios) and Chalkidiki (Stratoni) in Greece characterized by exorbitant metallurgical activities. Firstly, a literature search in databases such as ScienceDirect, SciFinder, PubMed, Google Scholar, and Scopus was conducted, using the following keywords to identify relevant articles: "utilization", "plants", "phytoremediation", "sustainability", "environment", and "restoration". Two case studies have subsequently been chosen in Northern Greece, one characterized by metal mining (Pb, Zn, Ag) and hot summer Mediterranean climate and another one involving lignite mining and concomitant Cr, Zn, Cu, and Ni pollution under subtropical climate. Based on the literature search some possible, non-invasive plant species were proposed, focusing on the most efficient hyperaccumulators.

The UF/IFAS Assessment of Nonnative Plants in Florida's Natural Areas: History, Purpose, and Use

Nonnative invasive plant species pose a significant threat to Florida’s natural areas. The UF/IFAS Assessment of Nonnative Plants in Florida’s Natural Areas uses literature-based risk assessment tools to predict the invasion risk of both nonnative species that occur in the state as well as species proposed for introduction. The UF/IFAS Assessment team has evaluated more than 900 species, including 208 species proposed for introduction or new uses. The team is actively identifying and evaluating potentially problematic nonnative species (and sub-specific or hybrid taxa). Recommendations and supporting information from the UF/IFAS Assessment can be found at http://assessment.ifas.ufl.edu.

Allelopathic effects of switchgrass on redroot pigweed and crabgrass growth

Non-native invasive plant species influence plant community composition and competitively eradicate native species. However, there is doubt regarding how global invasive species increase and explosively interfere with native plants. Invasive plants always have strong allelopathic potential. In this study, allelopathic effects of switchgrass on redroot pigweed and crabgrass growth were investigated by field and laboratory experiments. Within a 0.4-m distance of switchgrass, density and shoot biomass of native species were significantly suppressed in the field, with 95.1% and 93.0% inhibition on density of redroot pigweed and crabgrass and with 99.0% and 97.7% inhibition on shoot biomass, respectively, during the third growing season. Significant inhibitory effects on shoot and root biomass were observed at the 5:5 (switchgrass–native species) proportion in glass bottles, by 41.57% and 51.21% for shoot and root biomass of redroot pigweed and by 33.42% and 56.95% for shoot and root biomass of crabgrass, respectively. Results of a glass bottle experiment showed that shoot and root biomass of redroot pigweed and crabgrass could be significantly inhibited by contact with switchgrass root. Results of a Petri dish experiment showed that aqueous extracts of switchgrass significantly inhibited germination process of both species at high concentrations, with 90.74% and 18.62% inhibition on germination rate and plumule length of redroot pigweed and with 63.59%, 16.38%, and 19.92% inhibition on germination rate, plumule, and radicle lengths of crabgrass, respectively, at the concentration of 0.1 g·mL−1. This report demonstrated that switchgrass had allelopathic effects on redroot pigweed and crabgrass growth.

The influence of warming and biotic interactions on the potential for range expansion of native and nonnative species.

Plant species ranges are expected to shift in response to climate change, however, it is unclear how species interactions will affect range shifts. Because of the potential for enemy release of invasive nonnative plant species from species-specific soil pathogens, invasive plants may be able to shift ranges more readily than native plant species. Additionally, changing climatic conditions may alter soil microbial functioning, affecting plant–microbe interactions. We evaluated the effects of site, plant–soil microbe interactions, altered climate, and their interactions on the growth and germination of three congeneric shrub species, two native to southern and central Florida (Eugenia foetida and E. axillaris), and one nonnative invasive from south America (E. uniflora). We measured germination and biomass for these plant species in growth chambers grown under live and sterile soils from two sites within their current range, and one site in their expected range, simulating current (2010) and predicted future (2050) spring growing season temperatures in the new range. Soil microbes (microscopic bacteria, fungi, viruses and other organisms) had a net negative effect on the invasive plant, E. uniflora, across all sites and temperature treatments. This negative response to soil microbes suggests that E. uniflora’s invasive success and potential for range expansion are due to other contributing factors, e.g. higher germination and growth relative to native Eugenia. The effect of soil microbes on the native species depended on the geographic provenance of the microbes, and this may influence range expansion of these native species.

Plant cover restoration to inhibit seedling emergence, growth or survival of an exotic invasive plant species

ABSTRACT We conducted a mesocosm restoration experiment to test the efficacy of early summer sowing of seed mixtures for inhibiting the emergence, growth and/or survival of giant hogweed (Heracleum mantegazzianum) seedlings. H. mantegazzianum is invasive in Europe and North America, where it has a negative effect on plant diversity and represents a serious health hazard, due to the photodermatitis it may cause. We tested five plant mixtures comprising a selection of North American native or naturalized non-invasive plant species. Compared to the unseeded control mesocosm, all plant covers reduced seedling emergence, growth and survival of H. mantegazzianum. There were large differences between mixtures regarding inhibition effects. The nature of the effects depended on species composition, with one mixture more effective in preventing establishment, another essentially affecting seedling growth and survival. Total plant cover, irrespective of seed mixtures, appeared to have a major effect on H. mantegazzianum. Other factors that may have played a role included the litter from the seeded plants and the allelopathic effect of Canada goldenrod (Solidago canadensis). Our study adds to the growing body of evidence promoting the restoration of a plant cover as a means to prevent reinfestation by invasive species following a control operation.

Repeated, high-severity wildfire catalyzes invasion of non-native plant species in forests of the Klamath Mountains, northern California, USA

Non-native plant invasions are often catalyzed by wildfires and may alter the structure, function, and composition of ecosystems. Of particular concern are non-native annual grasses that promote increased fire frequency and compete with native vegetation for early season moisture. While these effects are well studied in non-forested ecosystems, relatively few studies document invasions of non-native annual grasses in forested ecosystems. We document non-native plant invasion following repeated high-severity wildfire in mixed-conifer/hardwood forests dominated by Douglas-fir (Pseudotsuga menziesii) in the Klamath Mountains of northern California. Despite great concern regarding the loss of conifer dominance and transitions to non-forested states related to recent and projected increases in wildfire activity, there is little known about invasions of non-native plant species following fire in this region. Non-native plant species capable of long-distance dispersal had an average total cover of 26% and were ubiquitous across a systematic, gridded sample of twenty 800 m2 plots. Non-native forbs included multiple species of common post-disturbance invaders (e.g. Cirsium vulgare, Senecio sylvaticus, Lactuca serriola). Non-native annual grasses comprised more of the vegetative cover than non-native forbs (17% vs. 9%), and were dominated by two species, Aira caryophyllea and Vulpia myuros, which reached as high as 80% cover. Our findings indicate that non-native annual grasses are a novel stressor that may accelerate projected loss of conifer dominance in the Klamath Mountains by facilitating fire spread and increasing competition for early season soil moisture. Additional monitoring will be crucial to understanding the impacts of non-native plants as fire activity in this region continues to increase.

Preliminary application of DNA barcoding toward the detection of viable plant propagules at an initial, international point-of-entry in Georgia, USA

Over 90% of global commercial trade occurs between seaports, which are initial points-of-entry for nonnative, potentially invasive propagules. As such, there is a need to develop means to both rapidly intercept and identify propagules as they arrive. Here, we focus on plant propagules that are assumed to be non-native, in seed form. Because standard morphological techniques alone are laborious and require taxonomic expertise, we sought to address if identification through barcoding of the plastid DNA (rbcL + matK genes) of plant seeds could improve current processes in the early detection and rapid response to prevent entry/establishment of nonnative plant species. This research conducted a preliminary foray to evaluate the utility of widely accepted plant plastid DNA barcodes to identify plant propagules (seeds, hereafter) collected from the air-intake grilles of refrigerated shipping containers of a single agricultural commodity arriving at the Port of Savannah, Georgia, USA. We ask four questions: (1) Can DNA barcoding be used to detect seeds collected from shipping containers at the port? (2) What is the genetic composition of propagules entering the port? (3) How do morphological identifications compare to those based on genetic analysis? (4) Are nonnative invasive plant species present on shipping containers entering the Port of Savannah? This research collected 11,044 seeds from 628 refrigerated shipping containers between 2015 and 2017. Seeds were then morphologically sorted into Seed Types. Barcoding of the matK and rbcL gene regions of the plastid genomes directly isolated from seeds resulted in poor amplification. This is likely due to a host of potential confounding factors. Therefore, we germinated seeds and utilized leaf-tissues for sequencing of these two gene regions. From BLASTn analyses, results returned top hits for a variety of species, with up to 22 possible nonnative plant species and one definite Federal Noxious Weed. This work investigates the interception application of DNA barcoding to improve agro- and bio-security issues posed by nonnative and invasive species. Though this study required the germination of the seeds to obtain leaf-tissue suitable for our DNA barcoding method, we effectively demonstrated seed viability. Our seed identification process was lengthy and understandably not feasible for real-time application. Therefore, we seek to improve our methods for future applications by testing other approaches that may better complement morphological identification. Next reasonable steps include improved extraction protocols, metabarcoding to generate DNA barcode sequences directly from groups of seeds harvested from shipping containers and implementing other next-generation sequencing techniques.

Community- and trophic-level responses of soil nematodes to removal of a non-native tree at different stages of invasion.

Success of invasive non-native plant species management is usually measured as changes in the abundance of the invasive plant species or native plant species following invader management, but more complex trophic responses to invader removal are often ignored or assumed. Moreover, the effects of invader removal at different stages of the invasion process is rarely evaluated, despite a growing recognition that invader impacts are density or stage-dependent. Therefore, the effectiveness of invasive species management for restoring community structure and function across trophic levels remains poorly understood. We determined how soil nematode diversity and community composition respond to removal of the globally invasive tree species Pinus contorta at different stages of invasion by reanalysing and expanding an earlier study including uninvaded vegetation (seedlings removed continuously), early invader removal (saplings removed), late removal (trees removed), and no removal (invaded). These treatments allowed us to evaluate the stage-dependent belowground trophic responses to biological invasion and removal. We found that invaded plots had half the nematode taxa richness compared to uninvaded plots, and that tree invasion altered the overall composition of the nematode community. Differences in nematode community composition between uninvaded nematode communities and those under the tree removal strategy tended to dilute higher up the food chain, whereas the composition of uninvaded vs. sapling removal strategies did not differ significantly. Conversely, the composition of invaded compared to uninvaded nematode communities differed across all trophic levels, altering the community structure and function. Specifically, invaded communities were structurally simplified compared to uninvaded communities, and had a higher proportion of short life cycle nematodes, characteristic of disturbed environments. We demonstrate that a shift in management strategies for a globally invasive tree species from removing trees to earlier removal of saplings is needed for maintaining the composition and structure of soil nematode communities to resemble uninvaded conditions.

Testing the Australian Post-Border Weed Risk Management (WRM) system for invasive plants in Iran

Given the global threat from invasive plant species, management systems are needed to determine the risk posed. Whilst pre-border weed risk assessment systems have been tested and applied broadly, risk assessment systems for species post-border (or weed risk management) are yet to be subjected to such levels of scrutiny. Here we adapted the Australian Weed Risk Management (AWRM) approach to the geographic, climatic and weed management context of Iran. Then we evaluated and tested the performance of the adapted WRM system using 38 candidate species, comprising both native and non-native invasive plant species present in Iran. Additionally we modified the post-border WRM approach by specifically focusing on the feasibility of containment, rather than control per se, given that eradication of native species is not appropriate; even when considered to be invasive. We also subsequently modified the management emphasis associated with each cell of the WRM matrix of weed risk and feasibility of containment levels, to account for the changes outlined above. We examined the effectiveness of the system using receiver operating characteristic (ROC) curves for the 38 candidate species, which showed that our results were similar to those observed during testing and evaluations of the WRM systems developed in Australia. Examination of the outcomes revealed that the current management and research for five of the highest priority species did not match or align with the level of risk derived from the WRM assessment. Additionally at least seven invasive plants species currently not on the lists examined should be included on the Noxious Weed lists of Iran based on our assessment of the risk posed. The two highest priority species (Ambrosia psilostachya and Imperata cylindrica) are both alien species and should be priorities for containment. Despite successfully modifying the AWRM for Iran, additional studies are required to further examine and test the best cut-off values for each risk level in the WRM matrix using larger numbers of plant species. Our results show that the AWRM can be modified for use in other countries, which could see broader adoption of post-border WRM systems for managing established alien plant species.