Responses of non-native and native plant species to fluctuations of water availability in a greenhouse experiment.

Water availability strongly influences the survival, growth, and reproduction of most terrestrial plant species. Experimental evidence has well documented the effect of changes in total amount of water availability on non-native vs. native plants. However, little is known about how fluctuations in water availability affect these two groups, although more extreme fluctuations in water availability increasingly occur with prolonged drought and extreme precipitation events. Here, we grew seven non-native and seven native plant species individually in the greenhouse. Then, we exposed them to four watering treatments, each treatment with the same total amount of water, but with different divisions: W1 (added water 16 times with 125 mL per time), W2 (8 times, 250 mL per time), W3 (4 times, 500 mL per time), and W4 (2 times, 1000 mL per time). We found that both non-native and native plants produced the most biomass under medium frequency/magnitude watering treatments (W2 and W3). Interestingly, non-native plants produced 34% more biomass with the infrequent, substantial watering treatment (W4) than with frequent, minor watering treatment (W1), whereas native plants showed opposite patterns, producing 26% more biomass with W1 than with W4. Differences in the ratio of root to shoot under few/large and many/small watering treatments of non-native vs. native species probably contributed to their different responses in biomass production. Our results advance the current understanding of the effect of water availability on non-native plants, which are affected not only by changes in amount of water availability but also by fluctuations in water availability. Furthermore, our results indicate that an increased few/large precipitation pattern expected under climate change conditions might further promote non-native plant invasions. Future field experiments with multiple phylogenetically controlled pairs of non-native and native species will be required to enhance our understanding of how water availability fluctuations impact on non-native invasions.

[Research on alien invasive plants in Jingzhou County, Hunan Province, China]. / æ¹–å—çœé–å·žåŽ¿å¤–æ¥å ¥ä¾µæ¤ç‰©ç ”ç©¶.

Harm from alien invasive plants is increasing in Jingzhou County, Hunan Province. Based on a one-year field investigation and available literature, we investigated species composition, origin, flora, degree of harm and distribution pattern of invasive plants in the county. The results showed that there were 34 invasive plant species from 27 genera and 16 families in this County. The dominant invasive species belonged to Asteraceae (8 species) and Amaranthaceae (6 species), which accounted for 23.5% and 17.7%, respectively. The majority of invasive plants originated from South America (45.7%) and North America (30.4%). Tropical flora showed a significantly higher representation than temperate flora, signifying robust tropical characteristics amongst the invasive plant population. Based on hazard level classification, we recognized four types as malicious invasion (Level 1): Alternanthera philoxeroides, Erigeron annuus, E. canadensis, and Xanthium chinense. In addition, five types were classified as severe invasion (Level 2), eight types as local invasion (Level 3), fifteen types as general invasion (Level 4), while two types were still under observation (Level 5). The pattern of distribution demonstrated that invasive plants in Jingzhou County mostly spread along the verges of transportation roads, in human settlements, and in a few areas of water flow. The higher levels of invasion damage were principally concentrated in the central part of Jingzhou County.

DNA barcoding of terrestrial invasive plant species in Southwest Michigan.

Because of the detrimental effects of terrestrial invasive plant species (TIPS) on native species, ecosystems, public health, and the economy, many countries have been actively looking for strategies to prevent the introduction and minimize the spread of TIPS. Fast and accurate detection of TIPS is essential to achieving these goals. Conventionally, invasive species monitoring has relied on morphological attributes. Recently, DNA-based species identification (i.e., DNA barcoding) has become more attractive. To investigate whether DNA barcoding can aid in the detection and management of TIPS, we visited multiple nature areas in Southwest Michigan and collected a small piece of leaf tissue from 91 representative terrestrial plant species, most of which are invasive. We extracted DNA from the leaf samples, amplified four genomic loci (ITS, rbcL, matK, and trnH-psbA) with PCR, and then purified and sequenced the PCR products. After careful examination of the sequencing data, we were able to identify reliable DNA barcode regions for most species and had an average PCR-and-sequencing success rate of 87.9%. We found that the species discrimination rate of a DNA barcode region is inversely related to the ease of PCR amplification and sequencing. Compared with rbcL and matK, ITS and trnH-psbA have better species discrimination rates (80.6% and 63.2%, respectively). When ITS and trnH-psbA are simultaneously used, the species discrimination rate increases to 97.1%. The high species/genus/family discrimination rates of DNA barcoding indicate that DNA barcoding can be successfully employed in TIPS identification. Further increases in the number of DNA barcode regions show little or no additional increases in the species discrimination rate, suggesting that dual-barcode approaches (e.g., ITS + trnH-psbA) might be the efficient and cost-effective method in DNA-based TIPS identification. Close inspection of nucleotide sequences at the four DNA barcode regions among related species demonstrates that DNA barcoding is especially useful in identifying TIPS that are morphologically similar to other species.

Response of Tahitian Bridal Veil (Gibasis pellucida) and Small-Leaf Spiderwort (Tradescantia fluminensis) to Postemergence Herbicides under Greenhouse Conditions.

Tahitian bridal veil (Gibasis pellucida) and small-leaf spiderwort (Tradescantia fluminensis) are both invasive species in natural areas throughout Florida. However, very little is known regarding herbicide control. To provide land managers with herbicidal control options for both species, postemergence herbicides were evaluated for efficacy in a greenhouse to identify herbicide options that control both species under similar settings. Four herbicides, including triclopyr acid, triclopyr amine + 2,4-D amine, triclopyr amine, and glufosinate were applied at standard label rates and compared to a non-treated control group for efficacy. Visual control ratings were taken at 2, 4, and 8 weeks after treatment (WAT), and shoot dry weights (WAT 8) and regrowth dry weights (WAT 12) were determined. Triclopyr (acid and amine) generally provided the most consistent control of both species as evidenced by the visual control ratings and shoot dry weight data which showed reductions of 76% to 89% in shoot biomass at trial conclusion. Triclopyr + 2,4-D reduced shoot dry weights by 52% to 54% and was the least effective when considering the control of both species.

Green synthesis of gold nanoparticles from the aqueous extracts of Sphagneticola trilobata (L.) J.F Pruski as anti-breast cancer agents.

The invasive plant, Sphagneticola trilobata (L.) J. F. Pruski, has been known for its bioactivities and used to synthesize gold nanoparticles (AuNPs). Nonetheless, previous research has not directly compared the effectiveness of the plant parts in producing the AuNPs. The objective of this study was to compare the effectiveness of the flower and leaf of S. trilobata in synthesizing AuNPs. S. trilobata leaves and flowers were separately extracted using distilled water at 60°C for 30 min. The leaf and flower extracts were mixed with the HAuCl. 3H2O and heated to 60°C for 30 min to yield AuNPs-ALSt and AuNPs-AFSt, respectively. AuNPs were also prepared using trisodium citrate (Na3C6H5O7) as a control. The resultant AuNPs were characterized using an ultraviolet-visible spectrophotometer, particle size analyzer, and scanning electron microscope. Antioxidant activity was evaluated based on 1-diphenyl-2-picrylhydrazyl (DPPH) inhibition and anticancer activity- 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay against MCF-7 cells. The AuNPs-ALSt and AuNPs-AFSt were revealed to have better stability and smaller particle diameters. AuNPs-ALSt and AuNPs-AFSt had average particle diameters of 11.86 ± 3.37 and 34.86 ± 23.56 nm, respectively. Agglomeration was predominantly observed in AuNPs synthesized using the flower or leaf extract as stipulated to be affected by the insufficient capping agent and intense hydrolytic reaction. AuNPs-AFSt had higher DPPH antioxidant activity than AuNPs-ALSt with half-maximal inhibitory concentrations of IC50 123.44 and 168.83 ppm, respectively. Both AuNPs-ALSt and AuNPs-AFSt could inhibit 80% growth of the MCF-7; however, at lower concentrations, inhibitory effects were more pronounced in AuNPs-AFSt. Aqueous extracts of S. trilobata flowers and leaves could be used to synthesize AuNPs, whereas the former yielded AuNPs with higher biological activities.

Alien plant species distribution in Romania: a nationwide survey following the implementation of the EU Regulation on Invasive Alien Species.

Background: Biological invasions pose an increasing risk to nature, social security and the economy, being ranked amongst the top five threats to biodiversity. Managing alien and invasive species is a priority for the European Union, as outlined in the EU Biodiversity Strategy for 2030 and the Kunming-Montreal Global Biodiversity Framework. Alien plant species are acknowledged to impact the economy and biodiversity; thus, analysing the distribution of such species provides valuable inputs for the management and decision-making processes. The database presented in the current study is the first consolidated checklist of alien plant species that are present in Romania, both of European Union concern and of national interest. This database complements a prior published distribution, based only on records from literature, bringing new information regarding the occurrence of alien plants in Romania, as revealed by a nationwide field survey. We consider this database a valuable instrument for managing biological invasions at both national and regional levels, as it can be utilised in further research studies and in drafting management and action plans, assisting stakeholders in making informed decisions and implementing management actions. New information: We present the results of the first nationwide survey of alien plant species in Romania, conducted between 2019 and 2022, in the framework of a national project coordinated by the Ministry of Environment, Waters and Forests and the University of Bucharest. The present database complements and updates the database published by Sirbu et. al (2022), which included occurrence records published until 2019. The new database includes 98323 occurrence records for 396 alien plant species in 77 families, with most species belonging to the Asteraceae family. One alien plant species in our database, the black locust Robiniapseudoacacia L., had more than 10,000 occurrence records. The distribution database also includes information on newly-reported invasive alien plant species of European Union concern in Romania (i.e. the floating primrose-willow Ludwigiapeploides (Kunth) P.H.Raven) and documents the presence of plants in 44 additional families compared to Sirbu et al. (2022). Each entry includes information on species taxonomy, location, year, person who recorded and identified the alien plant, geographical coordinates and taxon rank.

Chemical Basis for Determining the Allelopathic Potential of Invasive Plant Wall Barley (Hordeum murinum L. subsp. murinum).

The study investigated compounds present in the invasive grass Hordeum murinum L. subsp. murinum and tested the allelopathic potential of this plant against common meadow species Festuca rubra L. and Trifolium repens L. Gas chromatography-mass spectrometry (GC-MS) performed separately on the ears and stalks with leaves of wall barley revealed 32 compounds, including secondary metabolites, that may play an important role in allelopathy. Two compounds, N-butylbenzenesulfonamide (NBBS) and diphenylsulfone (DDS), were described for the first time for wall barley and the Poaceae family. The presence of 6,10,14-trimethylpentadecan-2-one (TMP) has also been documented. Aqueous extracts of H. murinum organs (ears and stalks with leaves) at concentrations of 2.5%, 5%, and 7.5% were used to evaluate its allelopathic potential. Compared to the control, all extracts inhibited germination and early growth stages of meadow species. The inhibitory effect was strongest at the highest concentration for both the underground and aboveground parts of the seedlings of the meadow species tested. Comparing the allelopathic effect, Trifolium repens proved to be more sensitive. In light of the results of the study, the removal of wall barley biomass appears to be important for the restoration of habitats where this species occurs due to its allelopathic potential.

Does the Invasive Heracleum mantegazzianum Influence Other Species by Allelopathy?

Heracleum mantegazzianum is an invasive species in middle Europe. The mode of action of its invasiveness is still not known. Our study focuses on observation of potential allelopathic influence by the production and release of phytochemicals into its environment. Plant material was collected four times within one season (April, May, June, July 2019) at locality Lekárovce (eastern Slovakia) for comparison of differences in composition and potential allelopathy. Water extracts from collected samples were used for different biological assays. The total phenols and flavonoids were determined spectrophotometrically. The profile and content of phenolic components, including coumarins, were determined by two techniques of liquid chromatography along with in vitro evaluation of the free radical scavenging activity of extracts (DPPH, Hydroxyl, Superoxide, and FRAP). The changes in composition in extracts in different seasonal periods were evident as well as potential phytotoxic activity in some concentrations on specific model plants. The slight antioxidant activity was noted. The invasiveness of the current species could be supported by the excretion of its phytochemicals into its surroundings and by different modes of action influencing living organisms in its environment.

An improved algorithm based on YOLOv5 for detecting Ambrosia trifida in UAV images.

A YOLOv5-based YOLOv5-KE unmanned aerial vehicle (UAV) image detection algorithm is proposed to address the low detection accuracy caused by the small size, high density, and overlapping leaves of Ambrosia trifida targets in UAV images. The YOLOv5-KE algorithm builds upon the YOLOv5 algorithm by adding a micro-scale detection layer, adjusting the hierarchical detection settings based on k-Means for Anchor Box, improving the loss function of CIoU, reselecting and improving the detection box fusion algorithm. Comparative validation experiments of the YOLOv5-KE algorithm for Ambrosia trifida recognition were conducted using a self-built dataset. The experimental results show that the best detection accuracy of Ambrosia trifida in UAV images is 93.9%, which is 15.2% higher than the original YOLOv5. Furthermore, this algorithm also outperforms other existing object detection algorithms such as YOLOv7, DC-YOLOv8, YOLO-NAS, RT-DETR, Faster RCNN, SSD, and Retina Net. Therefore, YOLOv5-KE is a practical algorithm for detecting Ambrosia trifida under complex field conditions. This algorithm shows good potential in detecting weeds of small, high-density, and overlapping leafy targets in UAV images, it could provide technical reference for the detection of similar plants.

Photosynthetic response dynamics in the invasive species Tithonia diversifolia and two co-occurring native shrub species under fluctuating light conditions.

To determine the invasiveness of invasive plants, many studies have compared photosynthetic traits or strategies between invasive and native species. However, few studies have compared the photosynthetic dynamics between invasive and native species during light fluctuations. We compared photosynthetic induction, relaxation dynamics and leaf traits between the invasive species, Tithonia diversifolia and two native species, Clerodendrum bungei and Blumea balsamifera, in full-sun and shady habitats. The photosynthetic dynamics and leaf traits differed among species. T. diversifolia showed a slower induction speed and stomatal opening response but had higher average intrinsic water-use efficiency than the two native species in full-sun habitats. Thus, the slow induction response may be attributed to the longer stomatal length in T. diversifolia. Habitat had a significant effect on photosynthetic dynamics in T. diversifolia and B. balsamifera but not in C. bungei. In shady habitat, T. diversifolia had a faster photosynthetic induction response than in full-sun habitat, leading to a higher average stomatal conductance during photosynthetic induction in T. diversifolia than in the two native species. In contrast, B. balsamifera had a larger stomatal length and slower photosynthetic induction and relaxation response in shady habitat than in full-sun habitat, resulting in higher carbon gain during photosynthetic relaxation. Nevertheless, in both habitats, T. diversifolia had an overall higher carbon gain during light fluctuations than the two native species. Our results indicated that T. diversifolia can adopt more effective response strategies under fluctuating light environments to maximize carbon gain, which may contribute to its successful invasion.

An emerging aeroallergen in Europe: Tree-of-Heaven (Ailanthus altissima [Mill.] Swingle) inventory and pollen concentrations - Taking a metropolitan region in Germany as an example.

Urban areas are often hotspots for the dissemination of non-native (invasive) plant species, some of which release (potentially) allergenic pollen. Given the high population density in cities, a considerable number of people can be regularly and potentially intensively exposed to the pollen from these plants. This study delves into the Tree-of-Heaven (Ailanthus altissima, [Mill.] Swingle), native to East Asia, which is known for its high invasiveness in temperate regions worldwide, particularly favoring urban colonization. This study explores the botanical and aerobiological dimensions of this species using the central European metropolitan region of Berlin, Germany, as a case study, and provides a comprehensive global overview of allergological insights. The number of Ailanthus trees decreased markedly from the center to the periphery of Berlin City, following a temperature gradient. The same spatial trend was mirrored by airborne Ailanthus pollen concentrations measured with volumetric spore traps (Hirst-type) at five sites using seven traps. Ailanthus pollen was most abundant around midday and in the afternoon, with concentrations tenfold higher at street level than at roof level. The Ailanthus flowering period in June and July coincided well with the pollen season. To the best of our knowledge this is the first study to investigate Ailanthus altissima pollen production. On average, 5539 pollen grains were found per anther. A literature review on the allergy relevance of Ailanthus altissima pollen indicates the high allergenic potential of pollen from this species. Considering the anticipated expansion of suitable habitats for Ailanthus owing to global warming and the allergological significance of its pollen, it is recommended to include Ailanthus pollen in routine pollen monitoring, particularly in areas colonized by this species. This comprehensive study provides new insights into a pollen taxon whose significance as an emerging aeroallergen should be factored into plant selection and greenspace management in all temperate regions.

Synthesis of magnetic MFe2O4 (M = Ni, Co, Zn, Fe) supported on porous carbons derived from Bidens pilosa weed and their adsorptive comparison of toxic dyes.

Bidens pilosa is classified as an invasive plant and has become a problematic weed to many agricultural crops. This species strongly germinates, grows and reproduces and competing for nutrients with local plants. To lessen the influence of Bidens pilosa, therefore, converting this harmful species into carbon materials as adsorbents in harm-to-wealth and valorization strategies is required. Here, we synthesized a series of magnetic composites based on MFe2O4 (M = Ni, Co, Zn, Fe) supported on porous carbon (MFOAC) derived from Bidens pilosa by a facile hydrothermal method. The Bidens pilosa carbon was initially activated by condensed H3PO4 to increase the surface chemistry. We observed that porous carbon loaded NiFe2O4 (NFOAC) reached the highest surface area (795.7 m2 g-1), followed by CoFe2O4/AC (449.1 m2 g-1), Fe3O4/AC (426.1 m2 g-1), ZnFe2O4/AC (409.5 m2 g-1). Morphological results showed nanoparticles were well-dispersed on the surface of carbon. RhB, MO, and MR dyes were used as adsorbate to test the adsorption by MFOAC. Effect of time (0-360 min), concentration (5-50 mg L-1), dosage (0.05-0.2 g L-1), and pH (3-9) on dyes adsorption onto MFOAC was investigated. It was found that NFOAC obtained the highest maximum adsorption capacity against dyes, RhB (107.96 mg g-1) < MO (148.05 mg g-1) < MR (153.1 mg g-1). Several mechanisms such as H bonding, π-π stacking, cation-π interaction, and electrostatic interaction were suggested. With sufficient stability and capacity, NFOAC can be used as potential adsorbent for real water treatment systems.

Impacts of Invasive Plants on Native Vegetation Communities in Wetland and Stream Mitigation.

We sampled vegetation communities across plant invasion gradients at multiple wetland and stream mitigation sites in the Coastal Plain and Piedmont physiographic provinces of Virginia, USA. Impacts of invasion were evaluated by tracking changes in species composition and native vegetation community properties along the abundance gradients of multiple plant invaders. We found that native species richness, diversity, and floristic quality were consistently highest at moderate levels of invasion (ca. 5-10% relative abundance of invader), regardless of the identity of the invasive species or the type of mitigation (wetland or stream). Likewise, native species composition was similar between uninvaded and moderately invaded areas, and only diminished when invaders were present at higher abundance values. Currently, low thresholds for invasive species performance standards (e.g., below 5% relative abundance of invader) compel mitigation managers to use non-selective control methods such as herbicides to reduce invasive plant cover. Our results suggest that this could cause indiscriminate mortality of desirable native species at much higher levels of richness, diversity, and floristic quality than previously thought. From our data, we recommend an invasive species performance standard of 10% relative invader(s) abundance on wetland and stream mitigation sites, in combination with vigilant invasive plant mapping strategies. Based on our results, this slightly higher standard would strike a balance between proactive management and unnecessary loss of plant community functions at the hands of compulsory invasive species management.

Spartina alterniflora invasion altered phosphorus retention and microbial phosphate solubilization of the Minjiang estuary wetland in southeastern China.

Spartina alterniflora invasion is considered a critical event affecting sediment phosphorus (P) availability and stock. However, P retention and microbial phosphate solubilization in the sediments invaded with or without S. alterniflora have not been fully investigated. In this study, a sequential fractionation method and high-throughput sequencing were used to analyze P transformation and the underlying microbial mechanisms in the sediments of no plant (NP) zone, transition (T) zone, and plant (P) zone. Results showed that except for organic phosphate (OP), total phosphate (TP), inorganic phosphate (IP), and available phosphate (AP) all followed a significant decrease trend from the NP site to the T site, and to the P site. The vertical decrease of TP, IP, and AP was also observed with an increase in soil depth. Among the six IP fractions, Fe-P, Oc-P, and Ca10-P were the predominant forms, while the presence of S. alterniflora resulted in an obvious P depletion except for Ca8-P and Al-P. Although S. alterniflora invasion did not significantly alter the alpha diversity of phosphate-solubilizing bacteria (PSB) harboring phoD gene, several PSB belonging to p_Proteobacteria, p_Planctomycetes, and p_Cyanobacteriota showed close correlations with P speciation and IP fractions. Further correlation analysis revealed that the reduced soil pH, soil TN and soil EC, and the increased soil TOC mediated by the invasion of S. alterniflora also significantly correlated to these PSB. Overall, this study elucidates the linkage between PSB and P speciation and provides new insights into understanding P retention and microbial P transformation in the coastal sediment invaded by S. alterniflora.

Spillover effects from invasive Acacia alter the plant-pollinator networks and seed production of native plants.

Invasive flowering plants can disrupt plant-pollinator networks. This is well documented where invasives occur amongst native plants; however, the potential for 'spillover' effects of invasives that form stands in adjacent habitats are less well understood. Here we quantify the impact of two invasive Australian species, Acacia saligna and Acacia longifolia, on the plant-pollinator networks in fynbos habitats in South Africa. We compared networks from replicate 1 ha plots of native vegetation (n = 21) that were subjected to three treatments: (1) at least 400 m from flowering Acacia; (2) adjacent to flowering Acacia, or (3) adjacent to flowering Acacia where all Acacia flowers were manually removed. We found that native flowers adjacent to stands of flowering Acacia received significantly more insect visits, especially from beetles and Apis mellifera capensis, and that visitation was more generalized. We also recorded visitation to, and the seed set of, three native flowering species and found that two received more insect visits, but produced fewer seeds, when adjacent to flowering Acacia. Our research shows that 'spillover' effects of invasive Acacia can lead to significant changes in visitation and seed production of native co-flowering species in neighbouring habitats-a factor to be considered when managing invaded landscapes.

DNA Barcoding of Invasive Terrestrial Plant Species in India.

Invasive plants are known to cause biodiversity loss and pose a major risk to human health and environment. Identification of invasive plants and distinguishing them from native species has been relied on morphological examination. Stringent requirement of floral characters and decreasing number of expert taxonomists are making conventional morphology-based identification system tedious and resource-intensive. DNA barcoding may help in quick identification of invasive species if distinct sequence divergence pattern at various taxonomic levels is observed. The present work evaluates the utility of four molecular markers; rbcL, matK, their combination (rbcL + matK), and psbA-trnH for identification of 37 invasive plant species from India and also in distinguishing them from 97 native species. A psbA-trnH locus was found to be of restricted utility in this work as it was represented by the members of a single family. A hierarchical increase in K2P mean divergence across different taxonomic levels was found to be the maximum for matK alone followed by rbcL + matK and rbcL alone, respectively. NJ clustering analysis, however, confirmed the suitability of combined locus (rbcL + matK) over individual rbcL and matK as the DNA barcode. RbcL showed the lowest resolution power among the three markers studied. MatK exhibited much better performance compared to rbcL alone in identifying most of the species accurately although it failed to show monophyly of genus Dinebra. Two families; Asteraceae and Poaceae, remained polyphyletic in the trees constructed by all three markers. Combined locus (rbcL + matK) was found to be the most suitable marker as it raised the resolution power of both the markers and could identify more than 90% of genera correctly. Phylogenetic tree constructed by Maximum-Parsimony method using combined locus as a molecular marker exhibited the best resolution, thus, supporting the significance of two-locus combination of rbcL + matK for barcoding invasive plant species from India. Present study contributes to the global barcode data of invasive plant species by adding fifty-one new sequences to it. Effective barcoding of additional number of native as well as invasive plant species from India is possible using this dual locus if it is combined with one or more new molecular plastid markers. Expansion of barcode database with a focus on barcode performance optimisation to improve discrimination ability at species level can be undertaken in future.

Isolation and identification of allelochemicals and their activities and functions.

Allelopathy is the interaction between donor plants and receiver plants through allelochemicals. According to a great number of publications, allelopathy may be involved in several ecological aspects such as the formation of monospecific stands and sparse understory vegetation for certain plant species. Allelopathy also contributes to the naturalization of invasive plant species in introduced ranges. Autotoxicity is a particular type of allelopathy involving certain compounds. Many medicinal plants have been reported to show relatively high allelopathic activity. We selected plant species that show high allelopathic activity and isolated allelochemicals through the bioassay-guided purification process. More than 100 allelochemicals, including novel compounds have been identified in some medicinal and invasive plants, plants forming monospecific stands, plants with sparse understory vegetation, and plants showing autotoxicity. The allelopathic activity of benzoxazinones and related compounds was also determined.

[Assessment of the current invasive situation of alien plants in semi-arid area of Northeast China]. / ä¸œåŒ—åŠå¹²æ—±åŒºå¤–æ¥æ¤ç‰©å ¥ä¾µçŽ°çŠ¶è¯„ä¼°.

Alien invasive plants have been found in the semi-arid region of Northeast China for a long time, but the overall invasion situation is rarely reported. In this study, we established a database of alien invasive plants in the semi-arid area of Northeast China through field investigation, specimen collection, research of specimen online information platform and literature. The results showed that there were 34 species of alien invasive plants belonging to 26 genera and 10 families in the semi-arid area of Northeast China, among which the Composite family had the largest number of richness, with 9 genera (34.6%) and 11 species (32.4%). There were 15 species (44.1%) in 11 genera (42.3%) of Legumes, Solanaceae and Gramineae. In all the alien invasive plants, 33 species were herbaceous plants, being overwhelmingly dominant (97.1%). There were both 7 species of countrywide invasive plants with invasive grade 1 and 2, each accounting for 20.6% of the total. The number of species with invasive grade 4 was the largest, 17 species, accounting for 50% of the total. The invasive plants originated in North America and Europe was the most, accounting for 64.7%, while those from South America, Asia and Africa accounted for 35.3%. Totally, 44.1% of all the invasive alien plants were intentionally introduced, while 55.9% were unintentionally introduced. In the semi-arid area of Northeast China, 81.3% of the counties (cities) had the distribution of alien invasive plants, and the invasion situation was very serious.

Microplastics and cadmium affect invasion success by altering complementarity and selection effects in native community.

The diversity-invasibility hypothesis predicts that native plant communities with high biodiversity should be more resistant to invasion than low biodiversity communities. However, observational studies have found that there is often a positive relationship between native community diversity and invasibility. Pollutants were not tested for their potential to cause this positive relationship. Here, we established native communities with three levels of diversity (1, 2 and 4 species) and introduced an invasive plant [Symphyotrichum subulatum (Michx.) G. L. Nesom] to test the effects of different pollutant treatments (i.e., unpolluted control, microplastics (MPs) alone, cadmium (Cd) alone, and their combination) on the relationship between native community diversity and community invasibility. Our results indicate that different MPs and Cd treatments altered the invasibility of native communities, but this effect may depend on the type of pollutant. MPs single treatment reduced invasion success, and the degree of reduction increased with increasing native community diversity (Diversity 2: - 14.1 %; Diversity 4: - 63.1 %). Cd single treatment increased the aboveground biomass of invasive plants (+ 40.2 %) and invasion success. The presence of MPs inhibited the contribution of Cd to invasion success. Furthermore, we found that the complementarity and selection effects of the native community were negatively correlated with invasion success, and their relative contributions to invasion success also depended on the pollutant type. We found new evidence of how pollutants affect the relationship between native community diversity and habitat invasibility, which provides new perspectives for understanding and managing biological invasions in the context of environmental pollution. This may contribute to promoting the conservation of biodiversity, especially in ecologically sensitive and polluted areas.

Plant ultrasound detection: a cost-effective method for identifying plant ultrasonic emissions.

Plants have been observed to produce short ultrasonic emissions (UEs), and current research is focusing on developing noninvasive techniques for recording and analyzing these emissions. A standardized methodology has not been established yet; in this paper we suggest a cost-effective procedure for recording, extracting, and identifying plant UEs using only a single ultrasound microphone, a laptop computer, and open-source software.