Search

Background: Resource competition is an important factor affecting the invasion success of alien plants, and environmental factors influence the competition outcomes between invasive and native plants. In this study, we explore the competitive pattern between invasive Chromolaena odorata and two native plant species under different phosphorus and irradiance levels. Results: The final biomass of each plant was regulated by both morphological and physiological traits. Invasive C. odorata did not always perform better than both native plants, and the competitive pattern between C. odorata and native plants was dependent on native competitor identity and environmental conditions. With competition, invasive C. odorata showed higher biomass (over 60%) than native Xanthium sibiricum under all treatments, but only showed higher biomass (about 20%) than native Eupatorium lindleyanum in normal irradiance treatments. The effect of phosphorus on competition depended on the irradiance level. Under normal irradiance, phosphorus addition increased (almost 10 times) the competitive index of invasive C. odorata; however, under shade irradiance, phosphorus addition decreased (40%) the competitive index of C. odorata. Conclusion: These results suggest that phosphorus, irradiance and native plant competitor together influence the relative performance of invasive C. odorata. In shade environment, selecting E. lindleyanum as competitor and increasing phosphorus level is an effective method for controlling the invasion of C. odorata. [ABSTRACT FROM AUTHOR]

Why nonnative invasive plant species commonly co‐occur, despite their competitive superiority and propensity to displace native species, remains a paradox in invasion biology. Negative interactions among competitively dominant invaders are potentially alleviated by two understudied mechanisms: seasonal priority effects, where phenological separation weakens the effect of competition on species with early phenology; and indirect facilitation, where competition between two species is mitigated by a third species. Although phenological separation has been speculated as a mechanism for explaining co‐occurrence patterns of invasive plants, it has never been directly tested. In a greenhouse experiment, we tested the effect of phenological separation on direct and indirect interactions between three co‐occurring invasive plant species found in the riparian forests of North America. These species have distinct natural phenological separation with reproduction in early spring (Ficaria verna), mid‐spring (Alliaria petiolata), and late summer (Microstegium vimineum). When phenology was experimentally synchronized, direct pairwise interactions among invasive species were overwhelmingly negative, asymmetric, and unlikely to promote co‐occurrence. However, increasing phenological separation generated seasonal priority effects, which weakened the effect of competition on species with early phenology. Furthermore, the addition of a third species generated indirect facilitative effects, which balanced competitive outcomes among the two weakest competitors. Based on these findings, we conclude that phenological separation modulates the strength of both seasonal priority effects and indirect facilitation within species interaction networks and may promote the co‐occurrence of three common invasive species within this study system. We articulate how future studies can test the external validity of these findings in more complex environmental conditions and with a larger range of invasive plants. [ABSTRACT FROM AUTHOR]

Land users' motives for participating in conservation and restoration activities are influenced by the local and broader scale contexts and are often determined by their perceptions of the current situation. Therefore, understanding land users' views is essential for gaining insights into the opportunities and constraints for ecosystem restoration. In this study, we sought to understand land users' perceptions of alien wattle (Acacia spp.) clearing activities and explore opportunities and challenges to wattle management as perceived by two groups of land users, i.e., communal land users and commercial livestock farmers, in the upper Umzimvubu catchment, South Africa. The results show marked differences in the key barriers and motives for participation by the two groups. Improvement in water flow was the most cited positive change from wattle clearing mentioned by commercial (75%) and communal (71%) farmers. Most commercial farmers (75%) cited improved grazing as one of the clearing benefits compared to only 39% of communal land users. Employment opportunity was a key motive mentioned by communal land users (25%). In contrast, most commercial farmers mentioned securing good grazing (50%) and water supply (33%) as important motives for removing wattle. Most commercial farmers mentioned high costs (35%) incurred when controlling wattle as the main barrier, whereas communal land users mentioned their old age (20%) and thus physical inability as the main barrier preventing them from maintaining cleared areas. These findings highlight the need to consider a mix of incentives that may effectively engage different land users in invasive alien plant clearing in different contexts. [ABSTRACT FROM AUTHOR]

Despite decades of research documenting the consequences of naturalized and invasive plant species on ecosystem functions, our understanding of the functional underpinnings of these changes remains rudimentary. This is partially due to ineffective scaling of trait differences between native and naturalized species to whole plant communities. Working with data from over 75,000 plots and over 5,500 species from across the United States, we show that changes in the functional composition of communities associated with increasing abundance of naturalized species mirror the differences in traits between native and naturalized plants. We find that communities with greater abundance of naturalized species are more resource acquisitive aboveground and belowground, shorter, more shallowly rooted, and increasingly aligned with an independent strategy for belowground resource acquisition via thin fine roots with high specific root length. We observe shifts toward herbaceous-dominated communities but shifts within both woody and herbaceous functional groups follow community-level patterns for most traits. Patterns are remarkably similar across desert, grassland, and forest ecosystems. Our results demonstrate that the establishment and spread of naturalized species, likely in combination with underlying environmental shifts, leads to predictable and consistent changes in community-level traits that can alter ecosystem functions. [ABSTRACT FROM AUTHOR]

Lines separating native and invasive plant species can be thin due to close relatedness, obscured by cryptic invasions, or breached by hybridization. Past work suggests these phenomena are especially prevalent in aquatic systems. This could arise from strong filters imposed by aquatic environments magnifying the importance of 'preadaptation'—non‐native species succeeding where closely related native species occur due to shared traits. If so, there should be stronger signals of preadaptation in aquatic than terrestrial plant invasions, with implications for management.I tested for stronger influence of preadaptation in aquatic than terrestrial invasions by comparing relatedness of invasive and native species in aquatic versus terrestrial flora of the Midwestern USA using herbarium records and taxonomic and phylogenetic analyses. I predicted that aquatic species would constitute an evolutionarily distinct subset of plants; aquatic invaders would be more closely related, taxonomically and phylogenetically, to native aquatic plants than terrestrial invaders are to their native counterparts; and aquatic invaders from the Midwest's primary donor region (the Palearctic) would be more closely related to Midwestern species than are Palearctic aquatic plants that are not invasive in the Midwest.Findings supported the evolutionary legacy of adaptation to aquatic environments being reflected in thin lines separating invasive and native aquatic plants. Aquatic species constituted an evolutionarily distinct subset of plants, and invasive aquatic plants were more closely related to native aquatic plants (taxonomically and phylogenetically) than terrestrial invaders were to terrestrial native species.Additionally, aquatic plants of the Palearctic that are invasive in the Midwest were more closely related to Midwestern natives (phylogenetically, but not taxonomically) than were their non‐invasive counterparts, reinforcing the role of preadaptation.Synthesis and applications: Thin lines separating native from invasive aquatic plants pose challenges for response efforts. For resource managers, the prevalence of cryptic invasions requires dedicated, robust approaches to surveillance. For outreach, finer distinctions between native and invasive necessitate nuanced approaches to communication and education. And when control is needed, it should be implemented cautiously to minimize nontarget impacts to close native relatives, but thoroughly enough to prevent native relatives being displaced by competition and/or introgression. [ABSTRACT FROM AUTHOR]

The proliferation of alien species that can suppress resident species via biotic interactions represents a growing concern worldwide. Yet, how above‐ and below‐ground communities simultaneously respond to plant invasion, particularly across large spatial scales, remains poorly explored. We hypothesized plant invasion has a greater impact on recipient above‐ and below‐ground communities at lower than higher latitudes given that biotic interactions play a more significant role in shaping communities in more favourable, lower latitude environments.To test this hypothesis, we conducted a comprehensive field survey of 124 sites spanning a 1700‐km latitudinal gradient in China, to explore the effects of invasion of Alternanthera philoxeroides, a globally widespread invasive plant, on plant, soil fungal and above‐ground arthropod communities.Invasion of A. philoxeroides had divergent effects on beta diversity (i.e. variation in taxa composition among sites) of plants, above‐ground arthropods and soil saprotrophic fungi, with negative, neutral and positive responses, respectively. Notably, the compositional dissimilarity of plant and arthropod communities between adjacent invaded and non‐invaded sites remained constant across latitudes. In contrast, the compositional dissimilarity of the entire and pathogenic fungal communities between adjacent invaded and non‐invaded sites increased with latitude. This resulted in a decreasing difference in invasion effects on the composition of plant and fungal communities with increasing latitude.Synthesis. Our study provides novel insights into the complexities of invasion effects by revealing contrasting responses of above‐ and below‐ground communities to plant invasion across latitudes. The contrasting responses could weaken or reshape above‐ and below‐ground interactions, and, in turn, affect future species invasions and the functioning of terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Globally, numerous ecosystems have been co‐invaded by multiple exotic plant species that can have competitive or facilitative interactions with each other and with native plants. Invaded ecosystems often exhibit spatial heterogeneity in soil moisture and nutrient levels, with some habitats having more nutrient‐rich and moist soils than others. The stress‐gradient hypothesis predicts that plants are likely to engage in facilitative interactions when growing in stressful environments, such as nutrient‐deficient or water‐deficient soils. In contrast, when resources are abundant, competitive interactions between plants should prevail. The invasional meltdown hypothesis proposes that facilitative interactions between invasive species can enhance their establishment and amplify their ecological impact. Considering both hypotheses can offer insights into the complex interactions among invasive and native plants across environmental gradients. However, experimental tests of the effects of soil moisture and nutrient co‐limitation on interactions between invasive and native plants at both interspecific and intraspecific levels in light of these hypotheses are lacking. We performed a greenhouse pot experiment in which we cultivated individual focal plants from five congeneric pairs of invasive and native species. Each focal plant was subjected to one of three levels of plant–plant interactions: (1) intraspecific, in which the focal plant was grown with another individual of the same species; (2) interspecific, involving a native and an invasive plant; and (3) interspecific, involving two native or invasive individuals. These plant–plant interaction treatments were fully crossed with two levels of water availability (drought vs. well‐watered) and two levels of nutrient supply (low vs. high). Consistent with the stress‐gradient and invasional meltdown hypotheses, our findings show that under low‐nutrient conditions, the biomass production of invasive focal plants was facilitated by invasive interspecific neighbors. However, under high‐nutrient conditions, the biomass production of invasive focal plants was suppressed by invasive interspecific neighbors. When competing with native interspecific neighbors, high‐nutrient conditions similarly enhanced the biomass production of both invasive and native focal plants. Invasive and native focal plants were neither competitively suppressed nor facilitated by conspecific neighbors. Taken together, these results suggest that co‐occurring invasive exotic plant species may facilitate each other in low‐nutrient habitats but compete in high‐nutrient habitats. [ABSTRACT FROM AUTHOR]

We conducted long-term monitoring of Hypogeococcus sp. (Pseudococcidae) as a biocontrol agent for queen of the night cactus (Cereus jamacaru De Candolle). The biocontrol agent was released at three sites representing the regions where the plant is problematic in South Africa, and both agent and plant populations were monitored over time. The proportion of plants producing fruits or flowers decreased by 36% each year, with all plants no longer flowering between two and seven years after release. Plant density reduced by 42% each year after release. Hypogeococcus sp. is an effective agent against C. jamacaru in South Africa. [ABSTRACT FROM AUTHOR]

Symbiotic organisms may contribute to a host plant's success or failure to grow, its ability to maintain viable populations, and potentially, its probability of establishment and spread outside its native range. Intercellular and intracellular microbial symbionts that are asymptomatic in their plant host during some or all of their life cycle – endophytes – can form mutualistic, commensal, or pathogenic relationships, and sometimes novel associations with alien plants. Fungal endophytes are likely the most common endosymbiont infecting plants, with life‐history, morphological, physiological, and plant‐symbiotic traits that are distinct from other endophytic guilds. Here, we review the community dynamics of fungal endophytes during the process of plant invasion, and how their functional role may shift during the different stages of invasion: transport, introduction (colonisation), establishment, and spread. Each invasion stage presents distinct ecological filters that an alien plant must overcome to advance to the subsequent stage of invasion. Endophytes can alternately aid the host in overcoming stage‐specific filters, or contribute to the barriers imposed by filters (e.g. biotic resistance), thereby affecting invasion pathways. A few fungi can be transported as seed endophytes from their native range and be vertically transmitted to future generations in the non‐native range, especially in graminoids. In other plant groups, alien plants mostly acquire endophytes via horizontal transmission from the invaded plant community, and the host endophyte community is shaped by host filtering and biogeographic factors (e.g. dispersal limitation, environmental filtering). Endophytes infecting alien plants (both those transported with their host and those accumulated in the non‐native range) may influence invasion success by affecting plant growth, reproduction, environmental tolerance, and pathogen and herbivory defences; however, the direction and magnitude of these effects can be contingent upon the host identity, life stage, ecological conditions, and invasion stage. This context dependence may cause endophytic fungi to shift to a non‐endophytic (e.g. pathogenic) functional life stage in the same or different hosts, which can modify alien–native plant community dynamics. We conclude by identifying paths in which alien hosts can exploit the context dependency of endophyte function in novel abiotic and biotic conditions and at the different stages of invasion. [ABSTRACT FROM AUTHOR]

Because of the high growth rates often achieved by invasive alien macrophytes, their establishment in recipient ecosystems may alter the abundance and composition of litter entering detrital pathways, representing a significant—but often overlooked—ecological effect of these invasions. Crassula helmsii (Kirk) Cockayne (New Zealand pygmyweed) is an invasive alien macrophyte, notorious for its profuse growth in invaded waterbodies. C. helmsii is perennial and often forms dense stands, producing abundant detritus. To investigate whether some of C. helmsii's impacts are mediated by this detritus, we conducted an 85-day litterbag experiment comparing decomposition of C. helmsii with that of Callitriche stagnalis Scop. (water-starwort), a commonly co-occurring native macrophyte. Macroinvertebrate assemblage composition was comparable between macrophyte species throughout the experiment, but shifted as plants decayed. Litterbags were initially dominated by the invasive shredder Crangonyx pseudogracilis Bousfield, 1958 and later by Euglesa casertana (Poli, 1791), an interstitial suspension feeder. C. helmsii litter decomposed more slowly, with proportionally less invertebrate-mediated breakdown, but was ultimately colonised by more abundant macroinvertebrates, including more C. pseudogracilis. Decomposition may be slowed by C. helmsii's high carbon: nitrogen ratio. These results suggest that C. helmsii invasion may impact macroinvertebrate assemblages via the production of long-lasting and relatively unpalatable detritus. [ABSTRACT FROM AUTHOR]

Vegetation cover has been consistently reported to be a factor influencing soil biota. Massive spreading of invasive plants may transform native plant communities, changing the quality of habitats as a result of modification of soil properties, most often having a directional effect on soil microorganisms and soil fauna. One of the most numerous microarthropods in the litter and soil is Acari. It has been shown that invasive plants usually have a negative effect on mites. We hypothesized that invasive Spiraea tomentosa affects the structure of the Uropodina community and that the abundance and species richness of Uropodina are lower in stands monodominated by S. tomentosa than in wet meadows free of this alien species. The research was carried out in wet meadows, where permanent plots were established in an invaded and uninvaded area of each meadow, soil samples were collected, soil moisture was determined and the mites were extracted. We found that Uropodina mite communities differed in the abundance of individual species but that the abundance and richness of species in their communities were similar. S. tomentosa invasion led primarily to changes in the quality of Uropodina communities, due to an increase in the shares of species from forest and hygrophilous habitats. Our results suggest that alien plant invasion does not always induce directional changes in mite assemblages, and conclude that the impact of an alien species on Uropodina may cause significant changes in the abundance and richness of individual species without causing significant changes in the abundance and diversity of their community. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) present a severe threat to native ecosystems and biodiversity. Comprehending the potential distribution patterns of these plant invaders and their responses to climate change is essential. Parthenium hysterophorus, native to the Americas, has become an aggressively invasive species since its introduction to China in the 1930s. This study aims to collect and reconstruct the historical occurrence and invasion of P. hysterophorus. Using the optimal MaxEnt model, the potential geographical distributions of P. hysterophorus were predicted based on screened species occurrences and environmental variables under the current and three future scenarios in the 2030s, 2050s, and 2070s (i.e., SSP1-2.6, SSP2-4.5, and SSP5-8.5), and the invasion risk of P. hysterophorus in Chinese cities, croplands, forests, and grasslands was assessed. The results show that: (1) The species initially invaded highly suitable areas and further spread to regions with non-analogous climate conditions. (2) Under the current climatic conditions, the overall potential distribution of P. hysterophorus is characterized by more in the southeast and less in the northwest. Climate variables, including mean annual temperature (bio1), precipitation in the wettest month (bio13), isothermality (bio3), and temperature seasonality (bio4), are the primary factors influencing its distribution. (3) The potential distribution of P. hysterophorus will expand further under future climate scenarios, particularly toward higher latitudes. (4) Forests and crop lands are the areas with the most serious potential invasion risk of P. hysterophorus. Therefore, we suggest that the government should strengthen the monitoring and management of P. hysterophorus to prevent its spread and protect agro-ecosystems and human habitats. Depending on the potential risk areas, measures such as quarantine, removal, and publicity should be taken to mitigate the threat of P. hysterophorus invasion and to raise awareness of P. hysterophorus invasion prevention. [ABSTRACT FROM AUTHOR]

Invasive plants disrupt ecosystems by influencing species interactions, aiding co-invader integration, and worsening competition for native plants. Successful forest invasive species management relies on grasping these interaction patterns at the community level. This study aims to assess the community attributes of invasive plants in tropical forests of Northeast India, examining their dominance in various habitats, elucidating their influence at the community level and some species-specific effects on associated co-invaders and non-invasive groups. The present investigation recorded 101 invasive plant species mostly of neotropical origin, comprising of grasses, sedges, forbs, shrubs, trees, and vines. The findings revealed both positive and negative effects of invasive species richness and their percentage at community level and throughout different habitats. However, the presence of dominant invasive species caused a substantial decrease in species diversity of plant community in the study area, depicting a significant negative association with the non-invasive group and a notable positive association with the co-invasive group. These findings offer valuable insights by specifying the community-level impacts of exotic invaders on the natural plant population which will be very helpful in devising effective management plans to counter biotic invasion in the biodiversity rich tropical forested landscapes. [ABSTRACT FROM AUTHOR]

The majority of allelopathic studies on invasive plants have focused primarily on their leaf-mediated allelopathy, with relatively little attention paid to their root-mediated allelopathy, especially co-allelopathy mediated by both leaves and roots. It is conceivable that the diversified composition of acid rain may influence the allelopathy of invasive plants. This study aimed to evaluate the leaf and root-mediated co-allelopathy of the invasive plant Solidago canadensis L. under acid rain with different nitrogen-sulfur ratios (N/S) on Lactuca sativa L. via a hydroponic incubation. The root-mediated allelopathy of S. canadensis was found to be more pronounced than the leaf-mediated allelopathy of S. canadensis with nitric acid at pH 4.5, but the leaf-mediated allelopathy of S. canadensis was observed to be more pronounced than the root-mediated allelopathy of S. canadensis with sulfuric-rich acid at pH 4.5. The leaf and root-mediated co-allelopathy of S. canadensis was more pronounced than that of either part alone with sulfuric acid at pH 5.6 and nitric acid at pH 4.5, but not with nitric-rich acid at pH 4.5 and sulfuric-rich acid at pH 4.5. Sulfuric acid and sulfuric-rich acid with stronger acidity intensified the leaf-mediated allelopathy of S. canadensis. Nitric acid and nitric-rich acid attenuated the leaf-mediated allelopathy of S. canadensis, and most types of acid rain (especially nitric acid and nitric-rich acid) also attenuated the root-mediated allelopathy of S. canadensis and the leaf and root-mediated co-allelopathy of S. canadensis. Sulfuric acid and sulfuric-rich acid produced a more pronounced effect than nitric acid and nitric-rich acid. Hence, the N/S ratio of acid rain influenced the allelopathy of S. canadensis under acid rain with multiple N/S ratios. [ABSTRACT FROM AUTHOR]

This study examines the spectral characteristics of two invasive plant species, Amur honeysuckle (Lonicera maackii) and Callery 'Bradford' pear (Pyrus calleryana Decne), in central Kentucky's recreational areas. Using a combination of spectrometer, satellite (National Agriculture Imagery Program (NAIP)) and unmanned aerial vehicle (UAV) data, this study investigated the correlation between leaf locations and normalized difference vegetation index (NDVI), as well as the impact of terrain features on vegetation indices. Significant variations in NDVI and normalized difference red-edge (NDRE) index values across study areas and leaf positions were observed. Terrain attributes, particularly slope and aspect direction, significantly influenced vegetative indices in one study site. Weak to moderate correlations were found between the spectrometer and UAV-derived NDVI and NDRE values. Additionally, the study highlighted the feasibility of upscaling UAV data for NAIP imagery comparison, reaffirming the superior accuracy of UAV imagery in assessing vegetation health. This integration of remote sensing techniques offers valuable insights into the spectral characteristics of invasive plants, essential for their effective mapping and management. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Location Taxon Methods Results Main Conclusions Previous local‐scale research (within plots or landscapes) has shown that invasive plants can alter the composition and diversity of soil microbial communities, with potential feedback effects on their own invasion success. However, the broader ecological patterns of these interactions across different invasion timescales and geographic regions remain poorly understood. This study investigated whether the composition and diversity of soil microbial communities associated with Solidago canadensis (Canada goldenrod) invasion vary across both population residence times and geographic locations.South‐eastern China.Soil fungal and bacterial communities and S. canadensis.We collected rhizospheric soil of S. canadensis, nonrhizospheric soil and adjacent uninvaded soil from each of 36 populations of S. canadensis with varying residence times (8–89 years), totalling 108 samples. We extracted DNA from these samples and sequenced the V3–V4 region of the bacterial 16S rRNA gene and the ITS2 region of the fungal rDNA. We analysed the DNA sequences to assess whether variation in α‐diversity, β‐diversity, arbuscular mycorrhizal fungi (AMF) richness and the ratio of AMF to plant pathogens in the soil microbial communities varied with S. canadensis population residence time, latitude and longitude.The α‐diversity and β‐diversity of soil fungal and bacterial communities significantly varied with S. canadensis residence times, latitude and longitude. In locations where S. canadensis had been established for longer periods, there was an increase in AMF richness and a decrease in plant pathogens in the rhizospheric soil. Fungal diversity in rhizospheric soils was positively correlated with longitude, while bacterial diversity in rhizospheric and nonrhizospheric soils was positively correlated with both latitude and longitude.These findings indicate that the time since invasion and geographical location can both significantly influence the composition and diversity of soil microbial communities associated with invasive plant species. [ABSTRACT FROM AUTHOR]

Summary Darwin's two opposing hypotheses, proposing that non‐native species closely or distantly related to native species are more likely to succeed, are known as ‘Darwin's Naturalization Conundrum’. Recently, invasion ecologists have sought to unravel these hypotheses. Studies that incorporate rich observational data in disturbed ecosystems that integrate phylogenetic and functional perspectives have potential to shed light on the conundrum. Using 313 invaded plant communities including 46 invasive plant species and 531 native plant species across the Three Gorges Reservoir Area in China, we aim to evaluate the coexistence mechanisms of invasive and native plants by integrating phylogenetic and functional dimensions at spatial and temporal scales. Our findings revealed that invasive plants tended to co‐occur more frequently with native plant species that were phylogenetically distant but functionally similar in the reservoir riparian zone. Furthermore, our study demonstrated that the filtering of flood‐dry‐flood cycles played a significant role in deepening functional similarities of native communities and invasive‐native species over time. Our study highlights the contrasting effects of phylogenetic relatedness and functional similarity between invasive and native species in highly flood‐disturbed habitats, providing new sights into Darwin's Naturalization Conundrum. [ABSTRACT FROM AUTHOR]

Although classical biological control makes use of natural enemies from the native range of an invasive alien species, there are occurrences in which species in the invaded range expand their host range and form new associations with the invader. Bagous longulus Gyllenhal (Coleoptera: Curculionidae) is a South African native weevil hosted by the native water lilies Nymphaea nouchali Burm. f. and Nymphaea lotus L. (family Nymphaeaceae), and it has formed a new association with the invasive alien water lily Nymphaea mexicana Zuccarini. Host range expansions of more-specialist native herbivores on alien invasive plant species occur relatively infrequently; therefore, we investigated the potential of this weevil as another means of managing N. mexicana in South Africa through augmentative biological control. Field surveys were conducted in 2021 and 2022 to determine the distribution of the weevil, and host-specificity tests were conducted under greenhouse conditions to understand its preference for its natural host as compared with N. mexicana and an exotic Nymphaea hybrid. The weevil was widely distributed at 31 surveyed sites across the country but was found feeding and completing lifecycles on only Nymphaea species, including the native hosts and the alien invasive N. mexicana. Additionally, there were no major differences in feeding preference for its natural host when compared with N. mexicana, but the Nymphaea hybrid tested was less preferred. The narrow host range of this weevil, its presence and impact on N. mexicana at three invaded sites, and the fact that a classical biological control agent has not yet been approved, all suggest a potential for B. longulus to be released augmentatively to manage N. mexicana in South Africa. Even so, possible risks such as increased herbivory on native Nymphaea species with augmented populations of its natural enemy should be carefully considered and tested before implementation. [ABSTRACT FROM AUTHOR]

Several attempts to eradicate invasive alien species have been initiated in South Africa and despite no formal eradication declaration, several species have been brought down to low levels or are now absent from the country. Based on an expert workshop with South African implementing agencies on best nationwide eradication practices, we recommend that eradication programmes should be well coordinated, and characterised by collaboration between implementing agencies, researchers and practitioners. Countries should have a list of eradication targets informed by the best available science, with targets ranked according to priority. The best eradication model should be used consistently until eradication is achieved. While most of these priority areas are not novel, it does provide a perspective from a biodiverse African country with limited funding, based on 16 years of experience in implementing eradication programmes. It corroborates challenges experienced elsewhere in the world and contributes to enhancing eradication outcomes globally. [ABSTRACT FROM AUTHOR]

Poplar is an invasive alien plant (IAP) that encroaches on fragile landscapes in South Africa, but the environmental factors that contribute to its spread are not well understood. To address this gap, we conducted a study using generalised linear models (GLM) to identify the most significant local environmental factors that drive poplar establishment and dispersion in Golden Gate Highlands National Park (GGHNP). We then ranked these variables according to their contribution to poplar occurrence using a random forests regression approach. Our GLM analysis revealed that soil properties such as soil organic carbon, sand and silt, topographical variables such as aspect and slope, normalised difference moisture index (NDMI) and poplar distance from rivers are significant factors affecting poplar survival. After ranking the variables, we found that the three most important factors influencing poplar occurrence were aspect, slope and poplar distance to rivers, followed by the sand, silt, NDMI, and soil organic carbon. Our results are consistent with previous studies, indicating that topographical variables and the availability of sufficient water supply are the primary drivers of the spread of IAPs. This study provides useful insights in managing and monitoring poplars in delicate landscapes. [ABSTRACT FROM AUTHOR]

Ecosystem restoration is a necessity for addressing socio‐ecological challenges by improving ecosystem resilience and alleviating poverty through local community involvement. Here, we review a community‐based, large‐scale ecosystem restoration program, Working for Ecosystems, implemented by eThekwini Municipality in KwaZulu‐Natal, South Africa, between 2007 and 2022. For this study, we interrogated monthly and annual reports generated by the program between 2011 and 2021 to describe how the program worked to suppress invasive alien plants (IAPs) and provided employment opportunities to marginalized groups (women, youth, military veterans, and people living with disabilities). Annual budget was positively correlated with the area cleared of IAPs and effort (person‐days in the field). The program successfully incorporated marginalized groups, but military veterans and people living with disabilities remained in smaller numbers and were not well quantified. Participants were encouraged to constitute companies—Small, Medium, and Micro Enterprises—that were then subcontracted to the program or could progress to other endeavors, allowing other community members to enter the program. A steady increase in the implementation budget emphasized the need for a long‐term plan to ensure accountability and sustainability of restoration and socio‐ecological systems. [ABSTRACT FROM AUTHOR]

We did a preliminary investigation of the allelopathic activity of 60 invasive and medicinal plants in Sri Lanka on Lactuca sativa (lettuce) and Raphanus sativus (radish). Out of 60 plants, 14 significantly reduced lettuce seedling lengths than distilled water, and 55 plants reduced radish seedling growth. In consideration of all the parameters tested, Cardiospermum halicacabum and Canarium zeylanicum Blume showed the highest phytotoxicity. C. zeylanicum (family Burseraceae), an endemic plant in Sri Lanka was selected for the isolation of phytotoxic compounds. The whole tree has a distinct fragrance bears edible seeds and has potential health benefits. This plant is used for medicinal purposes and its bark contains 3-hydroxy-12-methoxy-8,11,13-podocarpatrien-3-one and acetyl aleuritolic acid. This is the first report of the aforementioned two compounds from C. zeylanicum. These compounds exhibited phytotoxicity against lettuce. [ABSTRACT FROM AUTHOR]

Exotic plant invaders can promote others via direct or indirect facilitation, known as "invasional meltdown." Increased soil nutrients can also promote invaders by increasing their competitive impacts, but how this might affect meltdown is unknown. In a mesocosm experiment, we evaluated how eight exotic plant species and eight Eurasian native species responded individually to increasing densities of the invasive plant Conyza canadensis, while varying the supply and fluctuations of nutrients. We found that increasing density of C. canadensis intensified competitive suppression of natives but intensified facilitation of other exotics. Higher and fluctuating nutrients exacerbated the competitive effects on natives and facilitative effects on exotics. Overall, these results show a pronounced advantage of exotics over native target species with increased relative density of C. canadensis under high nutrient availability and fluctuation. We integrate these results with the observation that exotic species commonly drive increases in soil resources to suggest the Resource‐driven Invasional Meltdown and Inhibition of Natives hypothesis in which biotic acceleration of resource availability promotes other exotic species over native species, leading to invasional meltdown. [ABSTRACT FROM AUTHOR]

Seasonal variation in animal activity influences fitness and the intensity of ecological interactions (e.g., competition, predation), yet aspects of global change in the Anthropocene may catalyze shifts in seasonal activity. Invasive plants are components of global change and can modify animal daily activity, but their influence on animal seasonal activity is less understood. We examined how invasive woody shrubs (Autumn olive [Elaeagnus umbellata] and Amur honeysuckle [Lonicera maackii]) affect seasonal activity of three common small‐mammal species by coupling experimental shrub removal with autumnal camera trapping for two consecutive years at six paired forest sites (total 12 plots). Eastern chipmunks (Tamias striatus) foraged more, and foraging was observed at least 20 days longer, in shrub‐invaded forests. White‐footed mice (Peromyscus leucopus) foraged more in invaded than cleared plots in one study year, but P. leucopus autumn activity timing did not differ between shrub‐removal treatments. Fox squirrel (Sciurus niger) activity displayed year‐specific responses to shrub removal suggesting intraannual cues (e.g., temperature) structure S. niger autumnal activity. Our work highlights how plant invasions can have species‐specific effects on seasonal animal activity, may modify the timing of physiological processes (e.g., torpor), and could generate variation in animal‐mediated interactions such as seed dispersal or granivory. [ABSTRACT FROM AUTHOR]

Invasive alien species (IAS) are one amongst the dominant drivers of global environmental change. The reported effects of IAS on biodiversity and ecosystems are often highly variable across species, habitats, and environmental settings, which constrains our capacity to empirically generalise their overall impact. To date, meta‐analyses have investigated the ecological impacts of IAS using only mean effects, while variance effects – an equally important measure in quantifying the efficacy or generalizability of a treatment – has largely remained ignored. Using a global meta‐analysis of 586 and 522 effect sizes related to mean and variance measures respectively from 30 studies, here we provide the first quantitative synthesis of the extent to which a global plant invader Lantana camara affects the mean and variance of ecological variables relevant at species, community and ecosystem levels. Our results suggest that for individual response classes, both the mean and variance effects from the species invasion differed considerably in their magnitude and direction, with the effect on most response classes being highly heterogeneous and non‐significant. The study design had a significant effect on both the mean and variance effects from the species invasion, but the ecosystem type, continent, and latitude act as weak predictors of both mean and variance effects. By investigating both mean and variance effects, our study provides first quantitative synthesis on ecological impacts of a globally problematic invasive plant. Based on our findings, we highlight the current knowledge gaps and suggest future research directions, particularly the need to focus on causes of variance in invasion impact studies for effective management and restoration of invaded landscapes. [ABSTRACT FROM AUTHOR]

Aim: Due to the socioeconomic and environmental damages caused by invasive species, predicting the distribution of invasive plants is fundamental for effectively targeting management efforts. A habitat suitability model (HSM) is a powerful tool to predict potential habitat of invasive species to help guide the early detection of invasive plants. Despite numerous studies of the predictors used in HSMs, there is little consensus about the most appropriate predictors to use in creating ecologically realistic predictions from HSMs. Location: The contiguous United States. Methods: We explore 220 invasive terrestrial plant species' existing HSMs constructed with consistent modelling algorithms, background generation methods, predictor resolution, and geographic extent, and calculate the relative importance of predictors for each species. We sort predictors into eight groups (topography, temperature, disturbance, atmospheric water, landscape water, substrate, biotic interaction, and radiation) and compare the importance of predictor groups by plant lifeforms and phylogenetic relatedness. Results: Human modification and minimum winter temperature were generally the two highest performing individual predictors across the species studied. The highest‐performing predictor groups were disturbance, temperature, and atmospheric water. Across lifeforms, there were minimal differences in the influences of predictor groups, although woody plant models exhibited the largest differences in predictor importance when compared with non‐woody plant models. Additionally, we found no significant relationship between the importance of predictor groups and phylogenetic relatedness. Main Conclusions: This study has implications for informing predictor selection in invasive plant HSMs, leading to more reliable and accurate models of invasive terrestrial plants. Our results emphasize the need to critically select predictors included in HSMs, with special consideration to temperature and disturbance predictors, to accurately predict habitat of invasive plant for detection and response of invasive plant species. With more accurate predictions, managers will be better prepared to address invasive species and reduce their threats to landscapes. [ABSTRACT FROM AUTHOR]

The study aimed to assess the encroachment of woody plants on the rangelands of the Dallo Manna district of Bale Zone, and their impact on plant species diversity and pastoral livelihoods. Plant data were collected from 45 plots at encroaching sites and 4 plots at non-encroached sites, with a size of 20 m × 20 m for comparison. Data on pastoral perceptions were collected through questionnaires, interviews with key informants, and focus group discussions. A total of 62 woody species were recorded at both non-encroached and encroached sites, of which 58 species (93.5%) were recorded at non-encroached sites and 24 (38.7%) at encroached sites. Dichrostachys cinerea (L.) Wight and Arn. was the most abundant and dominant invasive woody species, followed by Senegalia mellifera (Vahl) Siegler and Ebinger, and Dalbergia microphylla Chiov. Overall, our results indicated that the effects of woody species encroachment significantly affected rangeland vegetation conditions and livelihoods. The major drivers for the encroachment were found to be fire suppression, overgrazing, and dispersal syndromes. However, in order to understand the exact causes of the woody plant encroachment, multiple variables should be considered in future research. For the successful control of encroachment, insights from an integrated approach will benefit from both local traditional and scientific knowledge of the ecology. [ABSTRACT FROM AUTHOR]

Euphorbia dentata Michx. is an invasive plant species in China, known for its toxicity and potential to reduce crop yields, posing numerous threats. To gain a deeper understanding of this invasive plant, phytochemical methods were employed to isolate 13 terpenoids (1–11, 19, 20) and 7 sterols (12–18) from the ethanol extract of E. dentata, identifying one new compound and 19 known compounds. Within spectroscopic methods such as NMR, HR-ESI-MS, and ECD, the structures and absolute configurations of these compounds were established. Among them, dentatacid A (11) possesses an unprecedented 2, 3-seco-arbor-2, 3-dioic skeleton within the potential biosynthetic pathway proposed. Dentatacid A also exhibited excellent anti-proliferative activity against the HT-29 (human colorectal adenocarcinoma) cell line, with an IC50 value of 2.64 ± 0.78 μM, which was further confirmed through network pharmacology and molecular docking. This study significantly expands the chemical diversity of E. dentata and offers new insights into the resource utilization and management of this invasive plant from the perspective of natural product discovery. [ABSTRACT FROM AUTHOR]

Invasive plant species pose a significant threat to global biodiversity and ecosystems. Climate changes favor the spread of non-native plants, whether voluntary or accidentally introduced into a new environment, as these plants possess a greater ability to adapt to changing environments. The spreading of these alien species has a negative impact also on agro-ecosystems, on agricultural yields, and on the nutritional quality of food crops. The high metabolic plasticity of these plants helps them to adapt to new ecosystems, enabling them to succeed in competing with crops. In particular, many alien plants are producers of alkaloids. These molecules represent the main chemical defense to biotic stressors and also the major risk for human health. In this review, we focused on invasive plants producing tropane alkaloids (TAs) and pyrrolizidine alkaloids (PAs). We explored the potential role of these molecules in the fitness of invasive plants in the context of climate change and reviewed the knowledge regarding their biosynthesis steps and examined the mechanism of toxicity when accidentally ingested. Finally, we summarized the most efficient analytical and molecular methods to detect either alkaloid contamination or the presence of invasive plant contaminants, which are the source of these molecules, in food crops. Possible solutions and precautions to ensure food safety have been also proposed. [ABSTRACT FROM AUTHOR]

Exposure to competition from invasive plants over multiple generations, or multigenerational invasive exposure can drive rapid native plant trait change. While invasive plant effects can be concentrated belowground, few studies consider native plant root trait responses to multigenerational invasive exposure. So, here we quantified root and shoot trait responses of the native grass Sporobolus airoides in response to multigenerational invasive exposure. S. airoides was sourced from invader-experienced subpopulations that co-occurred in the field for 58 years on average with invasive Russian knapweed (Rhaponticum repens) and from nearby invader-naïve plants that did not co-occur with the invasive. Maternal plants of these subpopulations were collected in the field, then transplanted to a greenhouse in Wyoming, USA. The first generation of seeds from these transplants were collected and grown for another round of seed collection (generation two). We grew invader-experienced and invader-naïve seedlings from both generations in a growth chamber in Illinois, USA. We found the largest shifts in root traits with invasive exposure status (e.g., for root mass fraction (standardized mean difference (SMD) = 0.5), primary root count (SMD) = 0.52), root length (SMD) = 0.44)); invader-experienced plants had significantly larger root traits in generation two, which was associated with greater survival, and thus may be adaptive. Since invader-experienced accessions have been evaluated as valuable restoration material in invaded sites, these findings highlight the need for continued root research in multigenerational invasive plant interactions and the need to evaluate more than one generation removed from a biotic influence. [ABSTRACT FROM AUTHOR]

Ornamental gardens are probably the most important source of invasive alien plants. However, the role of roadside shrines as a source of alien plant introductions remains unexplored. Herein, we are reporting the cultivated alien flora of a roadside shrine (devoted to the 'Difunta Correa') in south-eastern Spain, while making a prior assessment of the risk of spreading in the surroundings. In an area of less than 50 m2, up to 20 plant taxa were identified, with the vast majority of them being alien. Some of the observed alien taxa can be very problematic (e.g., Kalanchoe × houghtonii) and are even included in the Spanish catalogue of invasive species (such as Opuntia ficus-indica). Although the shrine is not affecting the local biodiversity yet (though a few taxa are showing the first signs of spread), it is located just 1 km away from a valuable protected area (included within the Natura 2000 network of the European Union and also recognized as a Ramsar site). Roadside shrines and similar places (e.g., memorials or calvaries) should be, thus, regarded as a potential source of alien plant introductions; thus, monitoring is recommended, particularly when close to protected areas. [ABSTRACT FROM AUTHOR]

Purposeful manipulation of biological control programs, such as timed releases of biological control agents, can be ephemeral and difficult to expand into new areas impacted by the targeted invasive plant. Integration of chemical ecology through attractive semiochemical lures to aggregate biological control agents to un-colonized areas can help mitigate this challenge. The invasive air potato vine, Dioscorea bulbifera L., is native to Asia and Africa with invasive infestations in the southeastern United States, Hawai'i, and Puerto Rico. In 2011, a host specific biological control agent, Lilioceris cheni (Coleoptera: Chrysomelidae), was introduced to manage D. bulbifera. Synthetic and racemic blends of previously identified attractive herbivory induced plant volatiles (HIPVs), ocimene and farnesene, were first evaluated for antennal response through electroantennography, then deployed as potential attractive lures in field conditions. Electroantennogram results validated the ability of adult male and female L. cheni to detect the two compounds. When used in field conditions, adult L. cheni beetles showed increased response to plants with ocimene and farnesene lures compared to control plants. The chemically enhanced lures increased L. cheni adult densities on D. bulbifera plants in the field compared to control plants. Plants with higher densities of L. cheni had greater direct herbivore feeding damage and observed cupped leaves, indicating the presence of oviposition and future larval development. The information gathered in this study indicated that the use of attractant semiochemical lures to purposefully aggregate and direct movement of biological control agents can improve the efficacy of invasive plant biocontrol programs. [ABSTRACT FROM AUTHOR]

Background: Previous studies into the interactions between native and invasive species under nitrogen (N) deposition have often overlooked the presence of co-occurring native species, a factor that could influence the outcomes of interspecific competition. Furthermore, publication bias may lead researchers to focus on rare native species with limited adaptability. In this study, we examined how two levels of N deposition affected the physiological and ecological traits and the interspecies interactions between three invasive and three common native species. Results: N deposition promoted the growth of both invasive and native species. The relative dominance index (RDI) of invasive species was consistently higher than that of native species. Invasive species had an advantage over common native species in using the increased N effectively. The biomass distribution of invasive species was biased toward the aboveground parts, indicating competition for light resources. Conclusions: N deposition conferred a stronger competitive advantage to invasive species than to native species, suggesting that the distribution range of invasive species may expand further under increased N deposition. [ABSTRACT FROM AUTHOR]

The Pacific Islands region is home to several of the world's biodiversity hotspots, yet its unique flora and fauna are under threat because of biological invasions. These invasions are likely to proliferate as human activity increases and large‐scale natural disturbances unfold, exacerbated by climate change. Remote sensing data and techniques provide a feasible method to map and monitor invasive plant species and inform invasive plant species management across the Pacific Islands region. We used case studies taken from literature retrieved from Google Scholar, 3 regional agencies’ digital libraries, and 2 online catalogs on invasive plant species management to examine the uptake and challenges faced in the implementation of remote sensing technology in the Pacific region. We synthesized remote sensing techniques and outlined their potential to detect and map invasive plant species based on species phenology, structural characteristics, and image texture algorithms. The application of remote sensing methods to detect invasive plant species was heavily reliant on species ecology, extent of invasion, and available geospatial and remotely sensed image data. However, current mechanisms that support invasive plant species management, including policy frameworks and geospatial data infrastructure, operated in isolation, leading to duplication of efforts and creating unsustainable solutions for the region. For remote sensing to support invasive plant species management in the region, key stakeholders including conservation managers, researchers, and practitioners; funding agencies; and regional organizations must invest, where possible, in the broader geospatial and environmental sector, integrate, and streamline policies and improve capacity and technology access. [ABSTRACT FROM AUTHOR]

Biological invasions pose a significant threat to ecosystems, disrupting local biodiversity and ecosystem functions. The genomic underpinnings of invasiveness, however, are still largely unknown, making it difficult to predict and manage invasive species effectively. The common reed (Phragmites australis) is a dominant grass species in wetland ecosystems and has become particularly invasive when transferred from Europe to North America. Here, we present a high-quality gap-free, telomere-to-telomere genome assembly of Phragmites australis consisting of 24 pseudochromosomes and a B chromosome. Fully phased subgenomes demonstrated considerable subgenome dominance and revealed the divergence of diploid progenitors approximately 30.9 million years ago. Comparative genomics using chromosome-level scaffolds for three other lineages and a previously published draft genome assembly of an invasive lineage revealed that gene family expansions in the form of tandem duplications may have contributed to the invasiveness of the lineage. This study sheds light on the genome evolution of Arundinoideae grasses and suggests that genetic drivers, such as gene family expansions and tandem duplications, may underly the processes of biological invasion in plants. These findings provide a crucial step toward understanding and managing the genetic basis of invasiveness in plant species. We provide a complete, telomere to telomere gap-free genome assembly for common reed that includes its B chromosome. Comparative genomic analysis revealed that tandem duplications may have contributed to the invasiveness potential of the species. [ABSTRACT FROM AUTHOR]

Drought may facilitate the invasion process of invasive plants, mainly because invasive plants can obtain a stronger growth competitiveness than native plants under drought. It is therefore imperative to illuminate the mechanisms underlying the successful invasion of invasive plants under drought, with a particular focus on the differences in the resistance of invasive and native plants to drought. This study aimed to elucidate the differences in the resistance between the invasive plant Amaranthus spinosus L. and the native plant A. tricolor L. to drought under a gradient of drought. The resistance of co-cultivated A. spinosus to drought was significantly higher than that of co-cultivated A. tricolor under light drought. Hence, A. spinosus may obtain a stronger competitive advantage than A. spinosus under co-cultivation conditions when treated with light drought. The resistance of the two plants to drought may be predominantly influenced by their height and biomass. This present study also defines a method for evaluating the stress resistance of a given plant species to stress by calculating the stress resistance index. This present study offers a robust theoretical foundation for determining the stress resistance of a given plant species and the environmental management of A. spinosus under drought. [ABSTRACT FROM AUTHOR]

The present study deals with an exploratory survey on the uses and role of invasive alien species (IAS) in the local Naga livelihoods in the mountainous region of eastern Himalayas. IAS was randomly sampled from an anthropogenic disturbed forest and a community protected forest to comparatively analyse the type of IAS prevailing in those conditions. Later, group discussions were arranged with local inhabitants to distinguish and identify the various uses of IAS. A total of 31 plant species belonging to 18 different families were identified, out of which 21 species were reported to be used as bio-resources. The majority of the identified species were found to possess medicinal or curative properties. Considering the importance of IAS despite some of their negative impacts, it is important to impart traditional knowledge of their uses to the upcoming generations and initiate necessary steps to distinguish harmful species from harmless ones for better ecological sustenance. [ABSTRACT FROM AUTHOR]

Invasive plants disrupt the structure and function of ecosystems, causing a decline in their diversity. The coexistence of Solidago canadensis and Erigeron canadensis within shared habitats is a common phenomenon, and the frequent occurrence of co‐invasion has substantial implications for ecosystems. However, the effects of the co‐invasion of two plants on the soil ecosystem across varying degrees of invasion remain uninvestigated. Therefore, we investigated how the co‐invasion of S. canadensis and E. canadensis affects soil physiochemical properties and microorganisms across various degrees of invasion. The invaded regions exhibited significantly lower soil moisture content and pH values than those in the uninvaded areas (p < .05). Additionally, co‐invasion resulted in higher soil organic matter (OM), total nitrogen (TN), total phosphorus (TP), and available phosphorus (AP) contents compared to single invasion by E. canadensis. Furthermore, the invaded regions exhibited a greater diversity of soil bacterial and fungal communities than the uninvaded regions. Under diverse invasion conditions, Actinobacteria and Ascomycota emerged as the predominant phyla of soil bacteria and fungi, respectively, leading to a shift in the soil microbial community structure. Moreover, homogenizing dispersal significantly influenced bacterial community succession, while ecological drift influenced the progression of fungal communities. Using structural equation modeling, this study established significant correlations between soil properties (pH, TN, and nitrate nitrogen) and bacterial interactions (diversity and community assembly) relative to microbial composition. This study revealed the influence of S. canadensis and E. canadensis co‐invasion on soil microbial communities, thereby contributing a theoretical framework delineating the impact of these two invasive plant species. [ABSTRACT FROM AUTHOR]

Solidago canadensis originated from North America, has become a notorious alien invasive plant widely distributed in China, which cause huge agricultural economic losses and serious ecological environment problems. In order to understand the invasive process and driving factors of S. canadensis in Hubei Province, combining with investigation, previous studies, news and media reports to collect the distribution sites of S. canadensis, the historical distribution dynamics of S. canadensis was simulated and reconstructed by the ArcGIS in Hubei Province. Moreover, the spread dynamics and its driving factors were analyzed by MaxEnt model. The results were as follows: (1) S. canadensis showed discontinuous aggregation distribution in Hubei Province. The early "jumping" invasion gradually transformed into the "gradual" spread from east to northwest Hubei in recent years. The Wuhan, Xianning and the central area of Yichang displayed the most serious invasion. (2) Human activities were the main factors promoting the spread of S. canadensis. It could move far away through transport along the road and railway. In addition, the invasive distribution sites of S. canadensis were positively correlated with human activity intensity and road network density in Hubei Province. (3) The precipitation of the driest quarter (Bio_17), temperature seasonality (Bio_4), mean temperature of the wettest quarter (Bio_8), the pH value of the soil (t_pH), the soil surface organic carbon content (t_oc) and the elevation (DEM) were key ecological factors affecting the propagation of S. canadensis. S. canadensis invaded easily with the t_pH value 4.0-7.5, the t_oc value 0.60%-1.12%, the Bio_4 value 880-920 and the Bio_8 value more than 24 °C. Moreover, the potential distribution areas suitable for medium and high adaptive growth of S. canadensis could reach up to 75 200 km². Combined with historical spread dynamics and affecting factors of S. canadensis invasion, the adaptive areas and invasive distribution sites have tended to reduce from east to west in Hubei Province, and the human activities is a major factor resulted in its invasion and distribution. Moreover, natural factors directly limit its population size and potential distribution areas at the invasion site in Hubei Province. This research provides theoretical support for risk assessment, monitoring and early warning, and prevention and control technologies of S. canadensis. [ABSTRACT FROM AUTHOR]

Alien invasive plants are commonly stated to pose a threat to populations of native plants, especially of endangered species. Resource allocation and nutrient strategies are important mechanism of invasion for alien plants. In order to investigate the distribution pattern, uptake and utilization strategies of invasive plants and their invasive, the carbon (C), nitrogen (N) and phosphorus (P) and biomass of the modules of invasive plants Praxelis clematidea and Synedrella nodiflora at different invasive degrees from eastern Guangdong were measured, and further the stoichiometric characteristics, allocation of nitrogen and phosphorus and relationship with soil factors were measured. The results were as follows: (1) Available nitrogen (AN) content in soil declined with increasing of invasive degree for Praxelis clematidea, and the N, P, AN contents in soil declined with increasing of the invasive degree for Synedrella nodiflora. The content of N (0.6962.701 g·kg-1) in soil of invasive habitat for Praxelis clematidea was greater than that for Synedrella nodiflora (0.189-0.337 g·kg-1), and the mean contents of C, P, available nitrogen (AN), and available phosphorus (AP) for Praxelis clematidea were less than those for Synedrella nodiflora. (2) For two plants with different invasive degrees, the N distribution for leaves was more than that for stems, and than roots. The P for Praxelis clematidea was distributed more to the stems, and for Synedrella nodiflora to the stems and leaves. The roots and stems of Praxelis clematidea, and leaves of Synedrella nodiflora with mild invasion had lowC: Pand N P values than severe invasive degree, indicating two plants with mild invasion may have fast relative growth rate, and strong expansion potential. The N P values in leaves for two plants were greater than those in roots and stems, implicating that roots and stems may have fast relative growth rate to increase the competitiveness of underground and above-ground. (3) The C: P and N P values in roots and stems of Praxelis clematidea at different invasive degrees were less than those of Synedrella nodiflora, while the C P and N P values in leaves of Synedrella nodiflora were less than that of Praxelis clematidea, showing that although the roots and stems of Praxelis clematidea may have faster relative growth rate, Synedrella nodiflora had faster relative growth rate and stronger invasion potential than Praxelis clematidea. (4) The allocation of nitrogen and phosphorus, and relative growth rate of alien plant Praxelis clematidea were mainly affected by AN, AP contents in soil, that relative growth rate of organs increased with increasing of AN, AP contents in soil. The allocation of nitrogen and phosphorus, and relative growth rate of alien plant Synedrella nodiflora were mainly affected by N, P contents in soil, that relative growth rate of organs increased with increasing of N, P contents in soil. In conclusion, the roots and stems of two Asteraceae alien species have fast relative growth rate, and further to increase the competitiveness of underground and above-ground, but their possible effect on N P stoichiometry requires further study. The results of this study have guiding significance for further understanding of resource allocation and utilization strategies and prediction of invasive potential of alien plants. [ABSTRACT FROM AUTHOR]

Introduction history, including propagule pressure and residence time, has been proposed as a primary driver of biological invasions. However, it is unclear whether introduction history increases the likelihood that a species will be invasive or only the likelihood that it will be established. Using a dataset of non‐native species historically available as ornamental plants in the conterminous United States, we investigated how introduction history relates to these stages of invasion. Introduction history was highly significant and a strong predictor of establishment, but only marginally significant and a poor predictor of invasive success. Propagule pressure predicted establishment better than residence time, with species likely to be established if they were introduced to only eight locations. These findings suggest that ongoing plant introductions will lead to widespread establishment but may not directly increase invasive success. Instead, other characteristics, like plant traits and local scale processes, may better predict whether a species becomes invasive. [ABSTRACT FROM AUTHOR]

Interest in plant pathogens for classical biological control (CBC) of invasive introduced plants has increased steadily since the 1970s. The introduced plant Passiflora foetida sensu lato invades large tracts of land across northern Australia and CBC represents a possible solution to reduce its abundance and spread. Field surveys for foliar fungal pathogens of P. foetida s.l. were performed between 2017 and 2020 in Colombia. Molecular sequencing was used to confirm the identity of plants surveyed at each site and to explore genetic variation between sites. Leaf spots of various sizes and sometime associated with chlorosis as well as necrosis of leaf edges were the main disease symptoms observed. These symptoms were not severe and did not appear to affect plant growth. No disease symptoms caused by obligate biotrophic fungi nor girdling lesions on stems were observed. Of the 125 fungal isolates recovered from the collected diseased material, only 21 were considered as pathogenic on P. foetida s.l. in detached-leaf assays. Morphological examinations and sequencing of the 21 pathogenic isolates revealed that they belong to 11 genera. Based on the low severity of disease symptoms observed in the field, we conclude that these isolates do not warrant further investigations as potential CBC agents. [ABSTRACT FROM AUTHOR]

Chemical signals are crucial in mediating ecological and evolutionary adaptation of plants to their environments. Indeed, invasive plants may produce greater amounts of chemical metabolites in their new ranges. Some of these chemicals can enhance their mutualistic interactions and improve invasive plant performance, but genetic mechanisms of such adaptations are unexplored.We used Triadica sebifera plants as a model to investigate evolutionary changes in chemical signals that enhance arbuscular mycorrhizal (AM) fungal associations. Previous studies found that T. sebifera plants from invasive populations had higher root exudate concentrations of the flavonoid quercetin and elevated AM fungal colonization compared with those from native populations. Here, we explored genetic variation in strigolactone concentrations in root exudates and their contribution to AM fungal colonization with strigolactone analogue GR24 additions. In addition, we studied how gene expression patterns related to flavonoid and strigolactone biosynthesis varied among invasive and native populations using comparative genomics, transcriptomics and fluorescent real‐time quantitative PCR.We found that plants from invasive populations had higher concentrations of the strigolactone 5‐deoxystrigol in root exudates that were correlated with higher AM fungal colonization rates, relative to those from native populations. Exogenous applications of GR24, a synthetic analogue of 5‐deoxystrigol, increased AM fungal colonization. We found higher expression of a single gene in flavonoid (FLS) and strigolactone (DAD1) biosynthesis pathways increased levels of quercetin and 5‐deoxystrigol in plants from invasive populations, respectively.Synthesis. Understanding the role of genetic evolution in enhancing mutualisms of invasive plants provides new insights into the underlying mechanisms of plant invasion. This study suggests that an invasive plant enhanced its mutualisms by upregulating the expression of key genes related to secondary metabolites in root exudates which stimulate symbiotic relationships with AM fungi. Thus, these findings provide insights into genetic mechanisms that underlie higher AM fungal colonization and enhanced invasive plant performance. [ABSTRACT FROM AUTHOR]

Plants that exhibit generalised pollination syndromes have been hypothesised to become invasive more easily compared with specialists, yet the degree to which specialised pollination traits inhibit plant invasions is unknown. One such specialisation is the buzz pollination syndrome, which encompasses specialised floral traits that restrict pollen access (typically poricidal anthers) and benefits from specialised insect behaviour for pollen extraction.We reviewed the literature on buzz pollination of invasive plants to assess whether: (1) plant species exhibiting specialised pollination syndromes are underrepresented as invasive species, and (2) species with specialised pollination syndromes that have become invasive can reproduce in the absence of specialist buzzing pollinators.Synthesis. We found 2.5% (117/4630) of invasive angiosperms have poricidal anthers, which is an underrepresentation of the proportion of global angiosperms that are estimated to have poricidal anthers (6%–10%). Most invasive buzz‐pollinated plants are genetically self‐compatible (97%), but only 43% can set fruit in the absence of a pollinator. Our findings highlight the importance of establishing new pollinator mutualisms for sexual reproduction. However, we identified six non‐buzzing behaviours used to extract pollen from plants with poricidal anthers, which is important where buzzing pollinators may be absent or not attracted to newly introduced plant species. [ABSTRACT FROM AUTHOR]

Urban protected biodiversity areas conserve some of the world's critically endangered and isolated biodiversity while providing essential ecosystem services. However, these urban habitats are threatened by the presence of alien and invasive plants. We studied alien plant species richness and identified the potential predictors in urban protected biodiversity areas in Tshwane Metropolitan Municipality, South Africa. Data on alien plant species were collected through surveys and consultations with protected area managers. We determined the relationship between the observed species richness and potential alien plant species predictors, such as area size, number of visitors, proximity to residential areas, and the year the reserve was proclaimed. We documented 574 records of 189 alien plant species from 60 families across 14 protected areas. Phanerophytes were the most common (46.5%), with many species native to South America, North America, and Africa. Most species have formed naturalised populations (67.7%), followed by invasive populations (20.6%) and casual populations (12%), posing future invasion threats. Most species (55.5%) were introduced as ornamental plants, with many of these species forming invasive populations. Half the recorded species were listed under the NEM:BA A&IS regulations, mostly categorized as 1b. Our findings indicate that the annual number of visitors strongly predicted alien plant species richness in urban protected areas. Additionally, a significant negative correlation was observed between species richness and the proximity to residential areas and years since the proclamation. Understanding the distribution patterns and predictors of species richness is crucial in monitoring invasive alien species and conserving biodiversity in urban environments. [ABSTRACT FROM AUTHOR]

Identifying characteristics of invasive species or growth forms that facilitate their range expansion is critical for management. Clematis vitalba L. (old man's beard) is an invasive temperate liana in many areas of its introduction, yet its seedlings do not thrive in circumstances where resources are limited. Although some lianas in both tropical and temperate climates have been shown to spread by clonal stems along the ground, the bulk of previous research on C. vitalba reproduction has focused largely on aspects of seed ecology. The vegetative growth of the species is poorly understood. The first objective of our study was to evaluate the use of vegetative spread by C. vitalba as a means of local dispersal and population growth. We excavated ten 1‐m2 plots in infested riparian zones and found an extensive, branching network of creeping stems, both above and below ground. Our second objective was to test the ability of C. vitalba stem fragments to act as vegetative propagules. After 4 months, ~50% of two‐node fragments had regenerated, from both creeping and climbing stems. These studies help explain how a temperate liana forms populations and dominate ecological communities. The findings provide good evidence that C. vitalba may rely quite heavily on asexual reproduction. In addition, the results document liana stem phenotypic plasticity; fragmented climbing stems are just as likely as fragmented creeping stems to reprogram shoot tissue systems, generate roots and regrow as independent plants. [ABSTRACT FROM AUTHOR]

Island ecosystems are particularly susceptible to the impacts of invasive species. Many rare and endangered species that are endemic to islands are negatively affected by invasions. Past studies have shown that the establishment of non‐native species on islands is related to native plant richness, habitat heterogeneity, island age, human activity, and climate. However, it is unclear whether the factors promoting establishment (i.e. the formation of self‐sustaining populations) also promote subsequent invasion (i.e. spread and negative impacts). Using data from 4308 non‐native plant species across 46 islands and archipelagos globally, we examined which biogeographic characteristics influence established and invasive plant richness using generalized linear models nested within piecewise structural equation models. Our results indicate that anthropogenic land use (i.e. human modification) is strongly associated with establishment but not invasion, that climate (maximum monthly temperature) is strongly associated with invasion but not establishment, and that habitat heterogeneity (represented by maximum elevation and island area) is strongly associated with both establishment and invasion. Island isolation explains native plant richness well, but is not associated with established and invasive plant richness, likely due to anthropogenic introductions. We conclude that anthropogenic land use on islands is likely to be a proxy for the number of introductions (i.e. propagule pressure), which is more important for establishment than invasion. Conversely, islands with more diverse habitats and favorable (warm) climate conditions are likely to contain more available niche space (i.e. ‘vacant niches') which create opportunities for both establishment and invasion. By evaluating multiple stages of the invasion process, we differentiate between the biogeographic characteristics that influence plant establishment (which does not necessarily lead to ecological impacts) versus those that influence subsequent plant invasion (which does lead to negative impacts). [ABSTRACT FROM AUTHOR]

The deposition of nitrogen in soil may be influenced by the presence of different nitrogen components, which may affect the accessibility of soil nitrogen and invasive plant–soil microbe interactions. This, in turn, may alter the success of invasive plants. This study aimed to clarify the influences of the invasive plant Bidens pilosa L. on the physicochemical properties, carbon and nitrogen contents, enzymatic activities, and bacterial communities in soil in comparison to the native plant Pterocypsela laciniata (Houtt.) Shih treated with simulated nitrogen deposition at 5 g nitrogen m−2 yr−1 in four forms (nitrate, ammonium, urea, and mixed nitrogen). Monocultural B. pilosa resulted in a notable increase in soil pH but a substantial decrease in the moisture, electrical conductivity, ammonium content, and the activities of polyphenol oxidase, β-xylosidase, FDA hydrolase, and sucrase in soil in comparison to the control. Co-cultivating B. pilosa and P. laciniata resulted in a notable increase in total soil organic carbon content in comparison to the control. Monocultural B. pilosa resulted in a notable decrease in soil bacterial alpha diversity in comparison to monocultural P. laciniata. Soil FDA hydrolase activity and soil bacterial alpha diversity, especially the indices of Shannon's diversity, Simpson's dominance, and Pielou's evenness, exhibited a notable decline under co-cultivated B. pilosa and P. laciniata treated with nitrate in comparison to those treated with ammonium, urea, and mixed nitrogen. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was conducted to determine the potential of arbuscular mycorrhizal fungi (AMF) to mitigate the allelopathic effects of invasive Nicotiana glauca on the growth of Acacia gerrardii seedlings. Aqueous extracts from N. glauca leaves and flowers (at concentrations of 20, 60, and 100 g/L) and AMF treatment (±AMF) were applied to A. gerrardii seedlings arranged in a factorial experiment with four replicates. After 6 months, vegetative (plant fresh and dry weight, height, leaf number area), physiological (photosynthesis, stomatal conductance, transpiration rate), chlorophyll a and b, proline, and root (length, surface area, diameter, volume, tip number) parameters as well as root distribution in five root diameter classes (0–5 mm, in 1 mm increments) were examined. The presence of AMF increased the seedling growth parameters. The 20 g/L treatment stimulated most of the vegetative growth, root, chlorophyll, and photosynthesis parameters at both inoculant levels for all extract types and concentrations, and the 100 g/L treatment inhibited seedling growth whether inoculated with AMF or not. This decline was alleviated in AMF-treated seedlings. For both extract sources, root length decreased as extract concentration increased, and roots <1 mm accounted for the greatest proportion of total root length, surface area, and tip number, with higher values observed in AMF-treated seedlings compared to their untreated counterparts. Further research is required at the field level to identify AMF strains and their interaction effects in alleviating the allelopathic impact of N. glauca on A. gerrardii seedling growth. [ABSTRACT FROM AUTHOR]

Ground-nesting bees are susceptible to disturbances that affect foraging resources, vegetation structure and soil characteristics. We studied the effects of 12 invasive alien plant species on environmental variables and directly on ground-nesting bees to reveal their specific importance. We sampled bees along transects; flowers, vegetation, bare ground and litter in quadrats, as well as soil characteristics. Our results suggested that plant invasion reduced overall and flowering plant richness and positively affected the height of native vegetation. However, this did not affect ground-nesting bees' abundance or species richness. Although we found invaded plots to have altered soil chemical characteristics compared to control plots, there was no correlation between soil characteristics and ground-nesting bees. The large explanatory potential of the random factors suggests that there were large differences in the abundance and species richness of ground-nesting bee species among the different habitat types and before and during the flowering of the invasive species. Although our study lacked a direct sampling of nesting bees, our results show the adverse effects of plant invasion on foraging and some nesting characteristics of ground-nesting bees. Future studies should put effort into the investigation of the number of nest holes and additional soil characteristics to get a better picture of the effects of plant invasion on ground-nesting activity. Implications for insect conservation: Our results suggest that ground-nesting bees are affected by alien plant invasion through their foraging resources, while plant invasion seemed to have a lower effect on nesting availability. Invasive alien plants should be eradicated and invaded areas restored to reduce adverse effects on the native plant community, soil and ultimately ground-nesting bees. [ABSTRACT FROM AUTHOR]