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Several European and North American countries have started releasing the Japanese knotweed psyllid, Aphalara itadori (Shinji) (Hemiptera: Aphalaridae), to control the Japanese knotweed, Reynoutria japonica Houtt. (Polygonaceae), and its relatives, which are among the worst invasive exotic plants. However, establishing populations of the currently released strains in the field has not been successful, desiring newly collected lineages. Moreover, little is known about the microbiome of the current strains, which potentially impacts properties as biocontrol agents. Hence, this study analyzed the microbiota of an A. itadori strain newly collected on Honshu Island, Japan, along with related species of the family Aphalaridae, using amplicon sequencing of 16S rRNA genes. The localization of symbionts identified in A. itadori was further analyzed using fluorescence in situ hybridization. The results demonstrated that the A. itadori bacteriome, a specialized organ for microbial symbiosis, maintains a dual symbiotic system with the primary symbiont "Candidatus Carsonella ruddii" (Gammaproteobacteria: Oceanospirillales: Halomonadaceae) and the secondary symbiont Sodalis sp. (Gammaproteobacteria: Enterobacterales: Pectobacteriaceae), suggesting that they are evolutionarily stable obligate mutualists for A. itadori. The central area of the bacteriome containing Sodalis comprised uninucleate bacteriocytes with nuclei larger than those of bacteriocytes harboring Carsonella. This observation contrasted previous reports on various psyllid lineages in which secondary symbionts are housed in a central syncytium with nuclei smaller than those of bacteriocytes for Carsonella. No known plant pathogens or parasitic manipulators of insect reproduction were identified in the analyzed A. itadori strain, indicating its suitability as a biocontrol agent, posing a minimum risk to the ecosystem. Besides distinct Carsonella lineages, Sodalis independently acquired by Craspedolepta miyatakeai Klimaszewski and an ambiguous Enterobacterales symbiont in Epheloscyta kalopanacis Loginova were identified. Only Carsonella was found in Togepsylla matsumurana Kuwayama. These results indicate repeated infections and replacements of bacterial symbionts during the evolution of Psylloidea, providing deeper insights into the microbe‐psyllid interactions. [ABSTRACT FROM AUTHOR]

Mauritius raspberry (Rubus rosifolius) is an exotic plant cultivated in Indonesia. Studies showed that the productivity of exotic plants is reducing due to a lack of pollination agent for their origin region. Several methods could be applied to overcome this problem. The study aimed to find the most effective method for pollinating this plant among four pollination regimes: Self-pollination, wild insects, stingless bees (Tetragonula laeviceps), and hand-pollination. The observation was conducted on the insect pollinators' activities (visitation rate, flower constancy, and flower handling time), pollination efficiency, and quality of the fruits produced (fruit volume). The results showed a higher visitation rate (10 to 70 per hour), higher flower constancy (visited from 07.00 to 16.00), and longer flower handling time (13.6 s) of T. laeviceps on raspberry flowers than other insects. High activities related to better raspberry pollination success (96%) and bigger fruits produced. Based on this study, applying stingless bees as pollination agents for exotic plants was the best and potentially applicable to other exotic crops. [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]

In the cities, remnants of the vegetation that originally occupied these areas can be found. Exotic species have established in these relicts, and therefore these spaces require management aimed at recovering native vegetation. In this study, we evaluated the impact of the removing exotic species on the floristic composition of the remnants of an oak forest. We compared the abundance/cover and composition of exotic plants in a forest that has been managed through citizen participation with that of reference forests (both with remnants, but the former without protection and the latter with protection). We established 48 sampling sites to characterize the vegetation in three strata (upper, middle, and low) and monitored changes in composition in managed forest sites for a period of 3 years. The results indicate that the managed forest hosts different species than those found in the reference forests, with lower abundance and cover of exotic plants in the upper and lower strata. Regarding temporal changes, we observed shifts in floristic composition before and after management activities, and a reduction in the cover of exotic species before and after management, with consistently low cover three years later. This underscores the effectiveness of citizen-led management activities, offering a viable alternative for restoring native vegetation in urban environments. [ABSTRACT FROM AUTHOR]

Biodiversity commonly contributes to ecosystem functioning and provides ecosystem services. Biochar application is frequently used to remediate soils contaminated with heavy metals. As many invasive plant species can quickly form huge amounts of biomass, they are potentially useful for producing biochar for remediating contaminated soils. However, it remains untested whether invasive species richness contributes to biochar-mediated soil remediation. We applied single biochar made from each of six invasive plant species and biochar mixtures (i.e., mixtures of biochar derived from 2, 3, and 6 invasive plant species) to soils contaminated with cadmium (Cd), with no biochar application as the control. We then grew native plant communities on these soils. Compared to the control, biochar application significantly decreased Cd bioavailability (− 34% averaged across the three richness treatments) in the soils, and this effect increased with increasing invasive species richness involved in the biochar mixtures (from − 22 to − 38%). Biochar application significantly increased both the concentration (+ 126%) and pool size (+ 59%) of Cd in roots of the native plant community, although it significantly decreased its biomass (− 25%). Thus, invasive species diversity can contribute to biochar-mediated remediation of soils contaminated with Cd. Our findings indicate a novel biodiversity-mediated ecosystem service, i.e., the use of multiple invasive plant species for the production of biochar. As harvesting of invasive species for biochar production may also contribute to their management, this might mitigate the two ecological problems at once. [ABSTRACT FROM AUTHOR]

In cities, human activities transform the native composition of plant communities into a mixture of native and exotic species. This new plant community shapes the composition of floral visitor communities persisting in urban environments. Recognizing the value of the diversity of urban pollinator communities can help quantify the conservation significance of cities. The aims of this work are: 1) to understand the effect of urbanization on flower visitors by comparing pollinator communities in natural and urban landscapes; 2) to quantify the influence of floral resources on floral visitors, and 3) to assess the impact of green spaces in urban environments on the composition of the flower-visitor community. We explored plant communities and floral visitors in five urban green spaces in a low urbanized city in Tucumán, Argentina, and in five natural protected areas located adjacent to the city. We found a greater diversity of flowering plants in the urban environment; mainly represented by exotic plant species and a lower diversity of the pollinator community than in the natural landscape. Pollinator diversity also showed a positive association with plant richness, while it was negatively affected by the proportion of exotic plants and the increase in flower density. Within city, distance to green spaces negatively affects the diversity of pollinators. Our results show that floral visitor communities in urban environments are less diverse than those in natural sites. Therefore, the composition of the plant community in the city, mainly exotic seems to affect communities of urban floral visitors. Our findings suggest that cities without intensive urbanization, and that still share many species with the closest natural space, may focus on urban planning that considers development alternatives that contribute to the conservation of pollinators.

Preparation of the country's flora is very challenging until baseline information on the flora of all district or upazila is available. The purpose of this inventory was to record angiosperm plant species available in the different habitats of Bagatipara upazila, which is located in the eastern part of Rajshahi district. The traditional taxonomic method was applied for plant sample collection in different seasons of the year 2022 and the identification of the collected samples. This research resulted in the recording of a total of 377 species in 92 families. Among them, 310 species were from Magnoliopsida, and 67 were from Liliopsida. Asteraceae and Poaceae were the leading families of Magnoliopsida and Liliopsida, respectively. One-fourth of the total plant species were exotic, and more than half were valuable medicinal species. Artocarpus lacucha, Bridelia stipularis, Callicarpa longifolia, Eranthemum pulchellum, Oroxylum indicum, Potentilla supina, Sterculia foetida, and Terminalia arjuna were locally found rare. Threats such as climate change, expansion of arable land and pisciculture, use of herbicides, over exploitation, clearing brushwood, and unplanned construction activities have been identified. The present study concludes that the floristic composition of this area is still rich, though the area is facing some threats. Therefore, we strongly recommend adopting effective and adequate measures for sustainable conservation and monitoring of the biodiversity of this area. [ABSTRACT FROM AUTHOR]

Wildflower areas are increasingly used in both urban and rural settings to enhance landscape aesthetics and help the conservation of pollinators, whose dramatic decline threatens both ecosystem functioning and agricultural production. Consequently, today many 'pollinator-friendly' wildflower seed mixes can be found on the market. Criteria for the design of these mixes are focused on the ability of the plants to attract pollinators, whereas the identity of the plants themselves in terms of their alien or native status is often not adequately considered. Moreover, seed mixes often lack sufficient floral resources in the early spring and late-season months, which are important to sustain pollinators throughout their whole life cycle. In this study, we analyzed 36 'pollinator-friendly' wildflower seed mixes commercially available in Italy in terms of (1) the abundance of native and alien species, (2) the occurrence of locally alien species with reference to three Italian geographic areas (northern, peninsular, and insular Italy), and (3) the flowering period of native and alien species. Most (83%) of the analyzed seed mixes contain species alien to Italy, with three of them also including invasive alien species. Among native species, many (41%) are locally alien to at least one of the geographic areas. Overall, native species provide earlier blooms than alien species and around 35% of the seed mixes lack blooms in early-spring (March) or prolonged throughout autumn (September-November). These findings highlight the widespread use of alien plant species in 'pollinator-friendly' wildflower mixes, which poses serious risks for biodiversity and habitat conservation, especially when sown in agricultural areas. We suggest a more careful design and use of such wildflower mixes, promoting a wider adoption of native seeds of local origin and a greater attention to the blooming period. If properly designed, wildflower mixes can represent an effective strategy for biodiversity conservation in both urban and rural areas. [ABSTRACT FROM AUTHOR]

The Enemy Release Hypothesis (ERH) suggests that the absence of natural enemies (herbivores, parasites, and diseases) in non-native environments allow exotic plants to allocate more resources towards growth and reproduction, resulting in increased invasiveness. This study uses the submerged macrophyte Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), native to Southern Africa, as a case study of this hypothesis. This species is invasive in many parts of the world, including Ireland, the United Kingdom and New Zealand. Here, we investigate the applicability of the ERH in explaining the invasiveness of L. major in New Zealand. This was achieved by comparing L. major biomass and cover, and plant species richness between L. major’s native range in South Africa and its invaded range in New Zealand, where specialist natural enemies were presumed to be lacking. The findings revealed significantly higher L. major biomass (∼100 % increase), cover (∼28 % increase) and shoot production (∼91 % increase) in the invaded range compared to the native range. Additionally, overall species richness and abundance was negatively correlated with L. major abundance in the invaded range. Plants in the native range were associated with more natural enemies and experienced higher levels of damage relative to the invaded sites. Overall, these observations align with the ERH, but should be interpreted with caution as other influential factors such as competition were not measured. Nevertheless, this suggests that L. major could benefit from the integration of biological control measures with the existing methods of control. Two natural enemies, Polypedilum tuburcinatum Andersen (Diptera: Chironomidae) and Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) have already been identified as promising candidates, for biological control of L. major in New Zealand and other regions invaded by this weed.

Simple Summary: We collected Lepidoptera (Phoebis spp., Pieridae) from native and exotic legume hostplants (species of Senna) over several years, rearing them to test the hypothesis that caterpillars on native hostplants would be parasitized more frequently than those on exotic hostplants. Our findings were the opposite of our prediction: greater rates of parasitization occurred on Pieridae using exotic hostplants. Are parasitoids less likely to find their Lepidoptera hosts on non-native hostplants than native hostplants? We predicted that with longer periods of coevolution between herbivores and the plants they consume, the parasitoids that provide top-down control would be more attuned to finding their hosts on native plants. To test this hypothesis, we collected immature stages of sulfur butterflies (the cloudless sulfur (Phoebis sennae) and the orange-barred sulfur (Phoebis agarithe) over a three-year period (2008–2011) from native and ornamental hostplants in the genus Senna in three different parts of the urban landscape of Miami, Florida, USA. We reared the immature specimens to pupation and either eclosion of adults or emergence of parasitoids and compared the levels of parasitization among the three areas, and among native vs. exotic hostplants. We found, contrary to our prediction, that caterpillars feeding on non-native leguminous hostplant species were more likely to be parasitized than those feeding on native hostplants. We discuss this surprising finding in the light of recent findings in other plant/herbivore/parasitoid systems. [ABSTRACT FROM AUTHOR]

Background: Urban gardens, despite their transformed nature, serve as invaluable microcosms for a quantitative examination of floral resource provision to urban pollinators, considering the plant's origin. Thus, knowledge has increased, emphasizing the importance of these green areas for hosting and conserving pollinator communities. However, there is a significant knowledge gap concerning the changing availability of these native and exotic floral resources over time and their impact on structuring interaction networks with specific pollinators. Methods: Over a year-long period, monthly surveys were conducted to record both native and exotic plant species visited by hummingbirds in an urban garden at Tlaxcala, Mexico. Flower visits were recorded, and the total flowers on each plant visited were tallied. Additionally, all observed hummingbirds were recorded during the transect walks, regardless of plant visits, to determine hummingbird abundance. The interactions were summarized using matrices, and network descriptors like connectance, specializacion, nestedness, and modularity were computed. Plant and hummingbird species in the core and periphery of the network were also identified. Lastly, simulations were performed to assess the network's resilience to the extinction of highly connected native and exotic plant species, including those previously situated in the network's core. Results: We recorded 4,674 interactions between 28 plant species, and eight hummingbird species. The majority of plants showed an ornithophilic syndrome, with 20 species considered exotic. Despite asynchronous flowering, there was overlap observed across different plant species throughout the year. Exotic plants like Jacaranda mimosifolia and Nicotiana glauca produced more flowers annually than native species. The abundance of hummingbirds varied throughout the study, with Saucerottia berillyna being the most abundant species. The plant-hummingbird network displayed high connectance, indicating generalization in their interaction. Significant nestedness was observed, mainly influenced by exotic plant species. The core of the network was enriched with exotic plants, while Basilinna leucotis and Cynanthus latirostris played central roles among hummingbirds. Network resilience to species extinction remained generally high. Conclusions: Our findings provide valuable insights into the dynamics and structure of plant-hummingbird interactions in urban gardens, emphasizing the influence of exotic plant species and the network's resilience to perturbations. Understanding and managing the impact of exotic plants on such networks is crucial for the conservation and sustainable functioning of urban ecosystems. [ABSTRACT FROM AUTHOR]

Aims: Most naturalized plants are escapees from cultivation. Inventories of cultivated introduced species thus offer unique, still underutilized, opportunities to assess naturalization drivers of introduced plants. We used a comprehensive inventory of 13,718 introduced species cultivated in China's botanical gardens to test which species characteristics distinguish the 739 species that have naturalized. Locations: China. Methods: We used generalized linear models to test whether the naturalization of cultivated introduced plants in China is associated with functional traits, propagule pressure, environmental niche and introduction history. To test direct and indirect effects of those variables and their relative importance in driving naturalization, we used structural equation models. Results: We showed that species were more likely to naturalize when they originate from the Americas, are more widely cultivated, and have a longer residence time. Moreover, species were more likely to naturalize if they have a good environmental match, are short‐lived herbs, are predominantly propagated from seeds, and, in the case of herbs, are relatively tall compared to other herbs. Part of the latter effects are mediated by how these variables relate to propagule pressure proxies, and this varies among short‐lived herbs, long‐lived herbs and woody plants. Main Conclusions: Naturalization is partly driven by life‐form‐dependent cultivation biases. [ABSTRACT FROM AUTHOR]

Background Urban gardens, despite their transformed nature, serve as invaluable microcosms for a quantitative examination of floral resource provision to urban pollinators, considering the plant’s origin. Thus, knowledge has increased, emphasizing the importance of these green areas for hosting and conserving pollinator communities. However, there is a significant knowledge gap concerning the changing availability of these native and exotic floral resources over time and their impact on structuring interaction networks with specific pollinators. Methods Over a year-long period, monthly surveys were conducted to record both native and exotic plant species visited by hummingbirds in an urban garden at Tlaxcala, Mexico. Flower visits were recorded, and the total flowers on each plant visited were tallied. Additionally, all observed hummingbirds were recorded during the transect walks, regardless of plant visits, to determine hummingbird abundance. The interactions were summarized using matrices, and network descriptors like connectance, specializacion, nestedness, and modularity were computed. Plant and hummingbird species in the core and periphery of the network were also identified. Lastly, simulations were performed to assess the network’s resilience to the extinction of highly connected native and exotic plant species, including those previously situated in the network’s core. Results We recorded 4,674 interactions between 28 plant species, and eight hummingbird species. The majority of plants showed an ornithophilic syndrome, with 20 species considered exotic. Despite asynchronous flowering, there was overlap observed across different plant species throughout the year. Exotic plants like Jacaranda mimosifolia and Nicotiana glauca produced more flowers annually than native species. The abundance of hummingbirds varied throughout the study, with Saucerottia berillyna being the most abundant species. The plant-hummingbird network displayed high connectance, indicating generalization in their interaction. Significant nestedness was observed, mainly influenced by exotic plant species. The core of the network was enriched with exotic plants, while Basilinna leucotis and Cynanthus latirostris played central roles among hummingbirds. Network resilience to species extinction remained generally high. Conclusions Our findings provide valuable insights into the dynamics and structure of plant-hummingbird interactions in urban gardens, emphasizing the influence of exotic plant species and the network’s resilience to perturbations. Understanding and managing the impact of exotic plants on such networks is crucial for the conservation and sustainable functioning of urban ecosystems.

The Revillagigedo Archipelago, located in the Eastern Pacific Ocean, stands out for its unique biological richness and endemism. These islands remained uninhabited until the second half of the twentieth century, allowing a better conservation status than on other oceanic islands. However, the continuous introduction of potentially invasive alien plant species, and the lack of adequate control or eradication actions, jeopardize the conservation and restoration of these islands' fragile ecosystems. We present the most complete vascular plant species inventory and an updated list of alien plant species of the Revillagigedo Archipelago, which was compiled through an extensive review of national and international plant collections and other sources. Our 272 species list includes 106 alien plant species (39.3%; 104 in Socorro, and 16 in Clarion): 67 (24.8%) are naturalized, 14 (5.2%) are casual aliens, and 25 (9.3%) subsist under cultivation. The documented alien species belong to 73 families. Annual and perennial herbs are the prevailing life forms in the alien flora, while naturalized species are primarily native to North America. The number of introduced species has increased significantly since the islands became inhabited. Many of the recently introduced species pose a major invasion risk like on other islands of the world. [ABSTRACT FROM AUTHOR]

This article describes distinctive soil properties within three Bornean tropical heath forest habitats associated with Acacia invasion in Brunei Darussalam. The data was systematically collected from eighteen 20 × 20 m plots set up within an Acacia mangium plantation, the adjacent intact heath forest, and Acacia mangium invaded heath forest. Within each plot, we collected eight soil cores from both topsoil and subsoil depths and measured soil pH, soil gravimetric water content, organic matter content, and concentrations of soil nutrients (total nitrogen, phosphorus, potassium, magnesium, and calcium, as well as exchangeable magnesium, calcium, and potassium and available phosphorus). Soil texture classification across all three habitats were also determined. This comprehensive dataset offers valuable insights into the ecological consequences of Acacia invasion into Bornean heath forests. Given the scarcity of studies focusing on diverse Bornean soil types and the impacts of invasive plants, our dataset can supplement future research efforts. Consequently, this dataset holds considerable value as a tool to offer insights to effectively address the challenge posed by exotic plant invasions on native tropical ecosystems.

Indirect facilitation among exotic species may promote their establishment on ecosystems, causing biodiversity losses. However, few experimental studies have identified the mechanisms underlying the indirect facilitation among exotic species. In central-northern Chile, Mesembryanthemum crystallinum (Aizoaceae) is an exotic halophyte that increases soil salinity, while M. nodiflorum is another exotic halophyte –currently less dominant– that often co-occurs with M. crystallinum. In this study, we evaluated the indirect facilitation of M. nodiflorum by M. crystallinum which was mediated by the suppression of salt-susceptible native competitors via increased soil salinity. We further determined the relationship between salt-tolerance traits and the outcome of competitive interactions in saline soil. We included two native Asteraceae plants co-occurring with these Mesembryanthemum species: the –highly probable– salt-susceptible Helenium urmenetae and the salt-tolerant Amblyopappus pusillus. We combined field co-occurrence surveys with greenhouse germination and competition experiments. The Mesembryanthemum species tended to co-occur, which suggests facilitation. Further, the salinity level found under M. crystallinum significantly decreased germination and performance of H. urmenetae, but not of M. nodiflorum and A. pusillus. Accordingly, when in competition, the increased salinity counteracted the negative effect of H. urmenetae on M. nodiflorum biomass, giving M. nodiflorum a competitive advantage. These patterns were associated with decreased specific leaf area and crassulacean acid metabolism expression in M. nodiflorum. In contrast, A. pusillus and M. nodiflorum maintained a neutral interaction regardless of salinity. Overall, our results suggest that M. crystallinum, by increasing soil salinity, may reduce the performance of salt-susceptible competitors, indirectly facilitating the establishment of M. nodiflorum. [ABSTRACT FROM AUTHOR]

Determining the factors that pre-adapt plant species to successfully establish and spread outside of their native ranges constitutes a powerful approach with great potential for management. While this source-area approach accounts for the bias associated with species' regions of origin, it has been only implemented in pools of species known to be established elsewhere. We argue that, in regions with well-known introduction histories, such as the Mediterranean Biome, the consideration of co-dominant non-introduced species as a control group allows a better understanding of the invasion process. For this purpose, we used occurrence data from GBIF and trait data from previous studies to find predictors of establishment and invasion. We compare the frequency, climatic niche and functional traits of 149 co-dominant plant species in their native region in southern Spain, considering whether they have colonised other Mediterranean-climate regions or not and their level of invasion. We found that large native ranges and diverse climatic niches were the best predictors of species establishment abroad. Moreover, coloniser species had longer bloom periods, higher growth rates and greater resource acquisition, whereas coloniser species becoming invasive had also greater reproductive height and nitrogen use efficiency. This framework has the potential to improve prediction models and management practices to prevent the harmful impacts from species in invaded communities. [ABSTRACT FROM AUTHOR]

Introduction: Atmospheric nitrogen (N) deposition has often been considered as a driver of exotic plant invasions. However, most related studies focused on the effects of soil N levels, and few on those of N forms, and few related studies were conducted in the fields. Methods: In this study, we grew Solanum rostratum, a notorious invader in arid/semi-arid and barren habitats, and two coexisting native plants Leymus chinensis and Agropyron cristatum in mono- and mixed cultures in the fields in Baicheng, northeast China, and investigated the effects of N levels and forms on the invasiveness of S. rostratum. Results: Compared with the two native plants, S. rostratumhad higher aboveground and total biomass in both mono- and mixed monocultures under all N treatments, and higher competitive ability under almost all N treatments. N addition enhanced the growth and competitive advantage of the invader under most conditions, and facilitated invasion successof S. rostratum. The growth and competitive ability of the invader were higher under low nitrate relative to low ammonium treatment. The advantages of the invader were associated with its higher total leaf area and lower root to shoot ratio compared with the two native plants. The invader also had a higher light-saturated photosynthetic rate than the two native plants in mixed culture (not significant under high nitrate condition), but not in monoculture. Discussion: Our results indicated that N (especially nitrate) deposition may also promote invasion of exotic plants in arid/semi-arid and barren habitats, and the effects of N forms and interspecific competition need to be taken into consideration when studying the effects of N deposition on invasion of exotic plants. [ABSTRACT FROM AUTHOR]

Invasive exotic plants often impact native plant species through strong competition, yet their effects can vary across different native populations. Previous exposure to invasive species but also differentiation along abiotic gradients may determine to what extent native populations are competitively suppressed by plant invasive species. Here, we experimentally investigated whether competitive effects of the invasive exotic jewelweed Impatiens parviflora on its native congener Impatiens noli‐tangere are related to previous exposure to the invader or rather to topography of the source populations, i.e. to terrain features such as elevation, aspect or slope. We also asked whether, in return, topographic settings of invasive I. parviflora populations may explain competitive effects of the native jewelweed. In a common garden competition experiment we found that populations of native jewelweed from colder, higher altitude sites and from drier sites were on average seven and six times, respectively, more tolerant to interspecific competition than populations from warmer and wetter sites. In contrast, previous exposure of native jewelweed populations to the invader was not a significant predictor of invader's competitive effects. Further, topographic settings of populations of invasive jewelweed were not significantly related to the native's competitive effects. Our study suggests that the native jewelweed's population differentiation along topographic gradients is more important in determining competitive interactions with an invasive congener than invasion‐induced selection. As fine‐scale environmental variation can shape adaptation of native species to the effects of invasive species, such variation should be considered when predicting invasive species' impact on native plant communities. [ABSTRACT FROM AUTHOR]

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Are parasitoids less likely to find their Lepidoptera hosts on non-native hostplants than native hostplants? We predicted that with longer periods of coevolution between herbivores and the plants they consume, the parasitoids that provide top-down control would be more attuned to finding their hosts on native plants. To test this hypothesis, we collected immature stages of sulfur butterflies (the cloudless sulfur (Phoebis sennae) and the orange-barred sulfur (Phoebis agarithe) over a three-year period (2008–2011) from native and ornamental hostplants in the genus Senna in three different parts of the urban landscape of Miami, Florida, USA. We reared the immature specimens to pupation and either eclosion of adults or emergence of parasitoids and compared the levels of parasitization among the three areas, and among native vs. exotic hostplants. We found, contrary to our prediction, that caterpillars feeding on non-native leguminous hostplant species were more likely to be parasitized than those feeding on native hostplants. We discuss this surprising finding in the light of recent findings in other plant/herbivore/parasitoid systems.

Abstract The present practice insight derives from land manager requests to document current on‐site activity and provides a management planning reference for restoration on Violet Prairie. Start‐up restoration initiates from trial‐and‐error adaptive management practices in the Puget Sound region of western Washington, USA. Treatments used focus on the implementation of staged‐scale restoration. Preparation intends to meet reintroduction goals of establishing a native plant community that could potentially support the threatened endemic Castilleja levisecta (golden paintbrush). Reintroduction of the associated native plant community provides habitat for endangered Euphydryas editha taylori (Taylor's checkerspot butterfly). Known conventional agricultural use coupled to fire suppression since the 1800s altered regional prairie lands to an unfavourable state for native plant species. Local native prairie soil types were favoured for growing conventional grasses and exotic forb species common to grazing pastures. Land abandonment and degradation has lengthened the time of disturbance and complicated restoring to a generalized reference point prior to settlement. Persistent exotic species, encroaching housing development, coniferous forest and recent wildfire complicate converting back to native prairie. Threatened and endangered species and their habitat are targeted in a trial‐and‐error process of staged‐scale adaptive management within the goal of whole ecosystem and connectivity restoration. Land managers focus on exotics removal and intensive native reseeding while restoring the use of prescribed burning as a maintenance tool. Embedded monitoring and observation advises where future practices need to be adapted by focusing on treatments and outcomes. Past land use practices replaced native soil seed banks with exotic seed banks that further distort reference proxies. Unknowns interrupt the current implementation additionally to soil conversion issues, while short‐term adaptive management methods initiate conversion back to native prairie. Species reintroduction choices to develop community structure are complicated by the fact that historical reference point species may be missing altogether from existing native communities. An unanswered outcome of the restoration process is determining which set of treatments best prepares soil for the desired native plant community.

Several studies have shown that invasive plant species respond more negatively to drought than native plant species, but little remains understood of how and whether drought‐rewetting events may affect growth of invasive and co‐occurring native plant species both directly and indirectly through soil microorganisms.In a fully crossed factorial design, we grew individuals of four congeneric pairs of invasive and native plant species in 2.5 L pots that contained live or sterilized field soil under one of three drought treatments: no‐drought, drought, drought‐rewetting.Results show that drought caused a significantly greater decline in total biomass of invasive plant species than that of native plant species regardless of the presence of live soil microorganisms. However, total biomass of the invasive plant species exhibited a greater recovery from drought following rewetting than did that of the native plant species. Moreover, recovery from drought in invasive plant species tended to be stronger in live soil than in sterilized soil, while for the native plant species, recovery from drought was stronger in sterilized soil than in live soil.Overall, these results suggest that in ecosystems that experience cycles of drought and rewetting, invasive plant species may grow larger than co‐occurring native plant species. Moreover, soil microorganisms may facilitate greater recovery from drought in invasive plant species than in co‐occurring native plant species. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

It is indisputable that invasive plant species strongly impact the ecosystems they invade. Many of such impacts can be negative and threaten the local species through competition, environmental change, or habitat loss. However, introduced plants may also have positive roles in the ecosystems they invade. This review extracted information from reports on common gorse (Ulex europaeus), one of the top 100 invasive plants on the earth, including its detrimental effects and potential beneficial roles in invaded ecosystems. The reduction of native fauna and flora are the main harmful effects of common gorse identified by the literature review. Soil impoverishment and fire hazards are other negative impacts reported for common gorse that could affect agricultural systems and local economies. Despite the negative impacts, reports of positive ecological services provided by common gorse also exist, e.g., as a nursery plant or habitat for endangered native animals. We also reviewed the known human uses of this plant that could support management strategies through harvest and benefit the local communities, including its use as biofuel, raw matter for xylan extraction, medicine, and food. Finally, our review identified the gaps in the literature regarding the understanding of the beneficial role of common gorse on native ecosystems and potential human uses, especially in the tropics. [ABSTRACT FROM AUTHOR]

Invasive plant species can modify ecosystem structure and function, potentially leading to the loss of native species, environmental and biotic homogenisation, changes in nutrient cycling, impairment of ecosystem services, and decrease in the rate of regeneration of plant recruits. We assessed the effects of the non-native and invasive vine Tradescantia zebrina on the germination and development of the native tree Hymenaea courbaril in north-eastern Brazil. We hypothesised that the invasive species would negatively impact the germination and development, and, via competition, the growth of the native species. We conducted a germination experiment for six months in seven forest patches. Seeds of H. courbaril were cultivated in four possible combinations of two treatments: under a cover with and without T. zebrina, and on soil that originated from places with and without T. zebrina present. Neither T. zebrina cover or soil affected the germination or biomass of H. courbaril during the experiment. H. courbaril seedlings were taller and had longer roots when cultivated in soil that originated from places with T. zebrina. T. zebrina presence alters soil properties in a way that triggers morphological responses in H. courbaril, which can be associated to a perceived competition context. [ABSTRACT FROM AUTHOR]

Remarkable studies have been conducted on the movement of plants from the Indies to France and the Jardin du Roi at Paris (today Muséum national d'Histoire naturelle). Researchers have seldom focused in detail on the links between the Île de France (now Mauritius) and the Gardens of Trianon during the reign of Louis XV.2 Scholars interested in bio-prospecting have established how France's colonial ambitions informed this trade; however, less attention has focused on alternative networks of botanists, collectors, and members of the medical community who pursued their passion for plants. Botanical enthusiasts at the court of Versailles, inspired by the Louis XV's patronage of his own botanical garden at the Petit Trianon, collaborating with the king's gardeners, pursued a botanical exchange with planters in the Île de France. Focusing on a diverse set of documents, this essay reconstructs the networks of travelers and naturalists who were sufficiently enthusiastic about exotic plants to have sponsored a collection of them in expensive greenhouses, and examines their collective wish to enrich the royal collection with seeds and plants drawn from the first plant collection gardens set up in Mauritius at the time of the French East India Company. [ABSTRACT FROM AUTHOR]

Remarkable studies have been conducted on the movement of plants from the Indies to France and the Jardin du Roi at Paris (today Muséum national d'Histoire naturelle). Researchers have seldom focused in detail on the links between the Île de France (now Mauritius) and the Gardens of Trianon during the reign of Louis XV.2 Scholars interested in bio-prospecting have established how France's colonial ambitions informed this trade; however, less attention has focused on alternative networks of botanists, collectors, and members of the medical community who pursued their passion for plants. Botanical enthusiasts at the court of Versailles, inspired by the Louis XV's patronage of his own botanical garden at the Petit Trianon, collaborating with the king's gardeners, pursued a botanical exchange with planters in the Île de France. Focusing on a diverse set of documents, this essay reconstructs the networks of travelers and naturalists who were sufficiently enthusiastic about exotic plants to have sponsored a collection of them in expensive greenhouses, and examines their collective wish to enrich the royal collection with seeds and plants drawn from the first plant collection gardens set up in Mauritius at the time of the French East India Company. [ABSTRACT FROM AUTHOR]

Invasive exotic species are problematic to biodiversity conservation. However, the knowledge of exotic invaders in tropical forests remains limited. Lessons from sites elsewhere suggest that the problem could be worse than is known. To increase our understanding of this problem, we surveyed exotic woody plants in Mabira Central Forest Reserve, Uganda. The site has a long history of anthropogenic disturbance. Seven woody exotic species were encountered, three of which had population structures indicative of invasiveness and distributions suggestive of the early stages of invasion. One of these species Senna spectabilis (DC.) H.S.Irwin & Barneby was localised to an 8.6 ha site north of the reserve. Terminalia superba Engl. & Diels occurred mainly in an 8.7 ha patch south of the reserve, while Artocarpus heterophyllus Lam. was more widely distributed. T. superba has been reported to be invasive in two other countries, but it is not yet clear whether or not the reported invasions are occurring in protected forests. A. heterophyllus is reported to be invasive in various countries, yet rarely quantitatively demonstrated outside the Brazilian Atlantic forests. S. spectabilis is a common invasive in forests throughout the tropics, and this is the first report of its invasiveness in this reserve. [ABSTRACT FROM AUTHOR]

In fragile ecosystems, the introduction of exotic species could alter some ecological processes. The Austral parakeet (Enicognathus ferrugineous) shows close ecological and evolutionary relationships with the Andean Araucaria (Araucaria araucana), so any alteration in these interactions may have negative consequences for both partners and for ecosystem functioning and structure. We conducted extensive roadside surveys to estimate the abundance of parakeets in the northern Patagonian Andes over 4 years and recorded the food plants consumed by foraging flocks. The use of native habitats and humanized areas like villages and farms was influenced by the Araucaria seed crop. In masting years, the large seed crop allowed a massive use of this resource during the non‐breeding season, and even during the breeding season. The exploitation of exotic plants was minor in the masting year, but became predominant in non‐masting years, especially during the non‐breeding season. This feeding switch towards exotic plants primarily arose because the low Araucaria seed crop in non‐masting years is entirely consumed just after production by domestic and wild exotic mammals living in Araucaria forests year‐round, thus forcing the displacement of parakeets towards anthropic habitats to exploit exotic plants. Given the degradation of the remaining Andean Araucaria forests due to the impact of exotic mammals on the ecological interaction between Araucaria and Austral parakeets, ambitious programs to exclude or reduce the density of these alien mammals, including livestock, are warranted. [ABSTRACT FROM AUTHOR]

Exotic plants could play an essential role in the restoration of heavy metal-contaminated soil. This study evaluated the tolerance of and extraction of cadmium (Cd) by ZCR (CR♀ × LT♂), hybrids of Xanthium strumarium (LT, exotic species) and X. sibiricum (CR, indigenous congener), and their parental species under different Cd treatments (0, 10, 40, and 80 mg·kg−1). The results showed that the hybrids had significantly improved tolerance to Cd. Under Cd stress, the biomass of ZCR increased by more than 50% on average compared with that of CR. Moreover, the hybrids showed a more remarkable ability to transport Cd from the root to the shoot. The Cd content of the shoots of ZCR increased by 128.33, 147.22, and 252.63% when treated with 10, 40, and 80 mg·kg−1 Cd, respectively. ZCR stored more than 70% of Cd in litter leaves, thereby reducing the toxic effects of Cd on photosynthesis and growth. The results showed that ZCR showed excellent Cd tolerance and enrichment in the presence of Cd. The hybrids of Xanthium strumarium and its native congener X. sibiricum may remediate soil Cd pollution. Novelty statement With the changing world economy and increasing human activities, exotic plants have become a global issue of common concern to the international community. This study describes new findings on using hybrids of the exotic plant of Xanthium strumarium and its native congener Xanthium sibiricum for the restoration of cadmium-contaminated soils. Under Cd stress, the hybrids' biomass, tolerance, and ability to accumulate Cd were significantly higher than that of X. sibiricum, indicating that hybrids gained useful heavy metal extraction traits from X. strumarium. [ABSTRACT FROM AUTHOR]

The article presents the results of archaeobotanical research from Vilnius, Rusų str. 5. The waterlogged sediment samples were taken from various archaeological contexts dated between the 16th–18th centuries. The abundance of botanical material and large diversity in plant species revealed the diet of past Vilnius inhabitants, the past use of diverse fruit species brown in orchards and in the forest, as well as exotic plants that were likely imported all the way from the southern Europe. The local ruderal vegetation infers of the past local environment at the excavated site.

Abstract In fragile ecosystems, the introduction of exotic species could alter some ecological processes. The Austral parakeet (Enicognathus ferrugineous) shows close ecological and evolutionary relationships with the Andean Araucaria (Araucaria araucana), so any alteration in these interactions may have negative consequences for both partners and for ecosystem functioning and structure. We conducted extensive roadside surveys to estimate the abundance of parakeets in the northern Patagonian Andes over 4 years and recorded the food plants consumed by foraging flocks. The use of native habitats and humanized areas like villages and farms was influenced by the Araucaria seed crop. In masting years, the large seed crop allowed a massive use of this resource during the non‐breeding season, and even during the breeding season. The exploitation of exotic plants was minor in the masting year, but became predominant in non‐masting years, especially during the non‐breeding season. This feeding switch towards exotic plants primarily arose because the low Araucaria seed crop in non‐masting years is entirely consumed just after production by domestic and wild exotic mammals living in Araucaria forests year‐round, thus forcing the displacement of parakeets towards anthropic habitats to exploit exotic plants. Given the degradation of the remaining Andean Araucaria forests due to the impact of exotic mammals on the ecological interaction between Araucaria and Austral parakeets, ambitious programs to exclude or reduce the density of these alien mammals, including livestock, are warranted.

Non-native plants are a major cause of habitat loss and fragmentation that lead to biodiversity loss. Geckos are particularly vulnerable to habitat alterations due to their small range and their restricted and specific terrestrial habits. However, our understanding of how introduced plants affect geckos, is poor. In this study, we investigate the potential effects of non-native and invasive neo-tropical tree Cedrela odorata on the critically endangered electric blue gecko, Lygodactylus williamsi, and its sole habitat, Pandanus rabaiensis. We used 107 square (10 m x 10 m) sample plots distributed systematically throughout the forest to assess the extent and effects of C. odorata on P. rabaiensis forest patches. We compared the abundance of L. williamsi on 125 P. rabaiensis trees growing in a mixture with C. odorata, native trees, and in pure stands and at three canopy cover categories (0–30%, >30–50%, and > 50%). We found an inverse relationship between the abundance of C. odorata trees (diameter at breast height (DBH)> 10 cm) and the abundance of P. rabaiensis. Spatially, the two trees dominated different parts of the forest. In contrast, the abundance of L. williamsi was not significantly affected by the presence of C. odorata. However, change in the canopy cover of the trees growing above the P. rabaiensis significantly affected the abundance of L. williamsi. The abundance of L. williamsi in a 0–30% cover was significantly higher than 30–50% and > 50% canopy covers. The findings of this study suggest that if left unmanaged, C. odorata could continue to take up the space that could be occupied by P. rabaiensis and other native plants, and thus limit the population size of an endangered species.

The Revillagigedo Archipelago, located in the Eastern Pacific Ocean, stands out for its unique biological richness and endemism. These islands remained uninhabited until the second half of the twentieth century, allowing a better conservation status than on other oceanic islands. However, the continuous introduction of potentially invasive alien plant species, and the lack of adequate control or eradication actions, jeopardize the conservation and restoration of these islands’ fragile ecosystems. We present the most complete vascular plant species inventory and an updated list of alien plant species of the Revillagigedo Archipelago, which was compiled through an extensive review of national and international plant collections and other sources. Our 272 species list includes 106 alien plant species (39.3%; 104 in Socorro, and 16 in Clarion): 67 (24.8%) are naturalized, 14 (5.2%) are casual aliens, and 25 (9.3%) subsist under cultivation. The documented alien species belong to 73 families. Annual and perennial herbs are the prevailing life forms in the alien flora, while naturalized species are primarily native to North America. The number of introduced species has increased significantly since the islands became inhabited. Many of the recently introduced species pose a major invasion risk like on other islands of the world.

Invasive Acacia species are known to modify soil properties, although effects are often site-specific. We examined the impact of Acacia species on the soils of intact and invaded habitats of two contrasting tropical lowland rain forest types in Brunei Darussalam: heath forest (HF) and mixed dipterocarp forest (MDF). Impacts on soil properties differed between the two forest types. Overall, Acacia-invaded HF soil recorded significantly higher gravimetric water content, pH and total P, K and Ca compared to the intact HF soil. In contrast, invaded MDF soil exhibited significantly higher organic matter content and total soil N, P, K and Mg compared to its intact habitat. Acacia-invaded MDF soils were more nutrient-enriched than Acacia-invaded HF soils by the addition of threefold, threefold and fourfold total soil P, K and Mg, respectively. The positive effect of addition of total soil Ca was, however, fourfold greater in HF soil than MDF soil, indicating that the magnitude of impact on soil properties was strongly site-specific. Overall, Acacia invasion significantly impacted soil properties in nutrient-rich MDF more than those of nutrient-poor HFs, indicating a potential vulnerability of MDFs to invasion. [ABSTRACT FROM AUTHOR]

Natural ecosystems generally include litter decomposition as part of the natural cycle since the material properties and the environment greatly influence the decomposition rate. The invasion of exotic plants alters the species diversity and growth characteristics of plant communities, but its impact on litter decomposition is unknown in the riparian zone. This study examines how invasive plants affect the early stages of litter decomposition and how species richness impacts them. This experiment involved a random litter mixture of exotic (Alternanthera philoxeroides and Bidens pilosa) and native species in the riparian zone of the Three Gorges Dam Reservoir in China. There were 43 species mixture types, with various species richness ranging from 1 to 6. Litterbags were placed in the hydro-fluctuation zone and terrestrial zone, where they decomposed over the course of 55 days. Invasive plants decompose rapidly compared to native plants (35.71% of the remaining mass of the invasive plant). The invasive plant A. philoxeroides has the potential to accelerate native plant decomposition (0.29 of non-added synergetic effect), but Bidens pilosa cannot. Nonetheless, species richness had little effect on the decomposition rate. These effects are dependent upon differences in chemical functional characteristics among the species. The initial traits of the plants, specifically C, N, and C/N, were significantly and linearly correlated with the loss of mixed litter mass and mixing effect strength (P < 0.01). In addition, submergence decomposition conditions reduce the disturbance of invasive plants and predict decomposition rates based on litter characteristics. Invasive plants can therefore impact the material cycle of an ecosystem. There is a need to examine decomposition time, which may also involve considering other factors. [ABSTRACT FROM AUTHOR]

ABSTRACT Exotic grasses have been introduced into wetlands and can compete with native plants due to their high tolerance of flood and dry periods. Flooding can facilitate seed dispersal of exotic species and reduce the diversity of native species. We compared two grasslands to assess whether seed banks can maintain the diversity of native plants in wetlands with introduced exotic plants. We recorded a total of 136 species and a predominance of annual plants in the seed bank and vegetation together. The seed bank had high species diversity independently of the dominance of the exotic Urochloa humidicola in the vegetation. The seed banks of the native and cultivated grasslands differed significantly with a positive correlation for aquatic plants in the native grassland and negative correlation in the cultivated grassland. The seed bank revealed potential to maintain the diversity of native species in the cultivated grassland since the flood and dry seasons promoted the presence of distinct species in the seed bank, but lower richness in the vegetation reflects a dependence on the germination stage. The seasonality of flood and dry periods influences distinct growth forms, increasing the diversity of the seed bank and the vegetation.

[Display omitted] • Higher L. major biomass and cover in invaded range compared to the native range. • Reduced overall species richness, and abundance in the invaded range. • Higher L. major damage in the native range compared to the invaded range. • More herbivore association in native range compared to the invaded range. • These findings are consistent with the assumption of Enemy Release Hypothesis. The Enemy Release Hypothesis (ERH) suggests that the absence of natural enemies (herbivores, parasites, and diseases) in non-native environments allow exotic plants to allocate more resources towards growth and reproduction, resulting in increased invasiveness. This study uses the submerged macrophyte Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), native to Southern Africa, as a case study of this hypothesis. This species is invasive in many parts of the world, including Ireland, the United Kingdom and New Zealand. Here, we investigate the applicability of the ERH in explaining the invasiveness of L. major in New Zealand. This was achieved by comparing L. major biomass and cover, and plant species richness between L. major 's native range in South Africa and its invaded range in New Zealand, where specialist natural enemies were presumed to be lacking. The findings revealed significantly higher L. major biomass (∼100 % increase), cover (∼28 % increase) and shoot production (∼91 % increase) in the invaded range compared to the native range. Additionally, overall species richness and abundance was negatively correlated with L. major abundance in the invaded range. Plants in the native range were associated with more natural enemies and experienced higher levels of damage relative to the invaded sites. Overall, these observations align with the ERH, but should be interpreted with caution as other influential factors such as competition were not measured. Nevertheless, this suggests that L. major could benefit from the integration of biological control measures with the existing methods of control. Two natural enemies, Polypedilum tuburcinatum Andersen (Diptera: Chironomidae) and Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) have already been identified as promising candidates, for biological control of L. major in New Zealand and other regions invaded by this weed. [ABSTRACT FROM AUTHOR]