[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of publi...[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of public gardens were recorded through point-line-surface investigation,and typical plants were sampled.[Results]There were 56 species of alien invasive plants in garden greenbelts of Shijiazhuang City,belonging to 44 genera and 20 families.In terms of life form,herbaceous plants were absolutely dominant,accounting for 92.8%of the total.The most alien invasive plants were native to America,accounting for 66.1%of the total.In terms of introduction path,the plants introduced artificially and unintentionally accounted for almost half.The species and quantity of alien invasive plants were related to the size of greenbelt area,the length of the build time of the surveyed plot,the composition structure of greenbelt and the level of green management and protection.There was larger distribution of alien invasive plants in the sample plots with large greenbelt area,long build time,herbaceous-dominated greenbelt and low level of green management and protection.Among the 56 alien invasive plants,3 plants were toxic.From the perspective of invasiveness,the alien invasive plants in the garden greenbelt of Shijiazhuang City could be divided into 5 levels:invasive alien species of malignant consequences,invasive alien species of severe consequences,invasive alien species of partial consequences,invasive alien species of average consequences,and invasive alien species to be observed.[Conclusions]This study will provide a reference for the prevention and control of alien plant invasion,and lay a foundation for the prevention and control of existing invasive plants.展开更多
According to the field survey of alien invasive plants of Jinziling,there were 23 kinds of alien invasive plants in the scenic spot.Species with the comprehensive dominance degree higher than 10% were as follows: six ...According to the field survey of alien invasive plants of Jinziling,there were 23 kinds of alien invasive plants in the scenic spot.Species with the comprehensive dominance degree higher than 10% were as follows: six kinds of Asteraceae: Bidens pilosa,Aster subulatus,Ageratum conyzoides,Conyzai canadens,Parthenium hysterophorus,and Conyza sumatrensis; two kinds of Gramineae: Axonopus compressu,Eleusine indica; two kinds of convolvere: Ipomoea nil,Ipomoea purpurea; two kinds of Fabaceae: Cassiae tora,Medicago hispida; one kind of Verbenaceae: Lantana camara; one kind of Euphorbiaceae: Euphorbia hirta.In total,there were 14 kinds of alien invasive plants.In this survey,the dominant species of invasive plants were obtained by statistical analysis of the composition and distribution of the invasive plants,and the invasion trend was predicted,so as to take effective and economical management and control measures.展开更多
A key scientific challenge relating to the threat of invasive plants on agriculture at the region level is to understand their adaptation and evolution in functional traits.Leaf functional traits,related to growth and...A key scientific challenge relating to the threat of invasive plants on agriculture at the region level is to understand their adaptation and evolution in functional traits.Leaf functional traits,related to growth and resource utilization,might lead to adaptation of invasive plants to the geographical barriers(region or elevation).In the field experiment,we discussed the effects of region and elevation on leaf functional traits on invasive plant Erigeron annuus in farmland habitats in China.We compared leaf size,coefficient of variation(CV)of leaf traits,and fluctuating asymmetry(FA)of E.annuus from three regions(east vs.center vs.west)and two leaf types(vegetative vs.reproductive leaf),and from nine elevations(980-2100 m)in the west region of China.Our results indicated region and leaf type influenced leaf functional traits,and leaf size was significantly higher and CV of leaf traits and FA in reproductive leaves were significantly lower in the east region than in the west and center regions.Elevation and leaf type affected leaf functional traits,and leaf size was significantly higher and CV of leaf traits in reproductive leaves were significantly lower in moderate elevation.E.annuus has higher leaf size and developmental stability(lower CV and FA)in the eastern region due to the longer adaptation period.Therefore,leaf functional traits play an important role in the adaptation of different longitudes and elevations.It can also facilitate the understanding of the invasiveness and adaptation of leaf traits of invasive plants in the agricultural ecosystem during their spread process in China.展开更多
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...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.展开更多
[Objectives]The paper was to investigate and assess the species,distribution and hazard status of invasive alien plants on the campus of Tongren University.[Methods]A survey was conducted using line survey method,and ...[Objectives]The paper was to investigate and assess the species,distribution and hazard status of invasive alien plants on the campus of Tongren University.[Methods]A survey was conducted using line survey method,and the risk assessment index system of invasive alien plants was established by analytic hierarchy process(AHP).[Results]There were 11 species of invasive alien plants on the campus of Tongren University,belonging to 8 genera and 5 families.There were 6 species of invasive alien plants belonging to Asteraceae,accounting for 54.55%of the total.In terms of the origin of invasive plants,most of them were native to North America and Europe,accounting for 27.27%of the total.In terms of harmful level,there were no high-risk invasive plants on the campus of Tongren University,but Alternanthera philoxeroides had the highest score and was the most harmful.[Conclusions]The present situation of alien plant invasion on the campus of Tongren University is closely related to the ecological environment of the campus.It is suggested to strengthen the management of campus plants,focus on the prevention and control of A.philoxeroides,and carry out regular investigation of invasive alien plants on campus to ensure the ecological safety of the campus.展开更多
Mikania micrantha is a fast-growing global invasive weed species that causes severe damage to natural ecosystems and very large economic losses of forest and crop production.It has advantages in photosynthesis,includi...Mikania micrantha is a fast-growing global invasive weed species that causes severe damage to natural ecosystems and very large economic losses of forest and crop production.It has advantages in photosynthesis,including a similar net photosynthetic rate as C4 plants and a higher carbon fixation capacity.We used a combination of genomics and transcriptomics approaches to study the evolutionary mechanisms and circadian expression patterns of M.micrantha.In M.micrantha,16 positive selection genes focused on photoreaction and utilization of photoassimilates.In different tissues,98.1%of the genes associated with photoresponse had high expression in stems,and more than half of the genes of the C4 cycle had higher expression in stems than in leaves.In stomatal opening and closing,2 genes of carbonic anhydrase(CAs)had higher expression at 18:00 than at 8:00,and the slow anion channel 1(SLAC1)and high-leaf-temperature 1 kinase(HT1)genes were expressed at low levels at 18:00.In addition,genes associated with photosynthesis had higher expression levels at 7:00 and 17:00.We hypothesized that M.micrantha may undergo photosynthesis in the stem and flower organs and that some stomata of the leaves were opening at night by CO_(2)signals.In addition,its evolution may attenuate photoinhibition at high light intensities,and enhance more efficient of photosynthesis during low light intensity.And the tissue-specific photosynthetic types and different diurnal pattern of photosynthetic-related genes may contribute to its rapid colonization of new habitats of M.micrantha.展开更多
Biological invasion is triggered by human development activities such as the construction and expansion of road networks.Road verges serve as important habitats and corridors for the distribution of invasive alien pla...Biological invasion is triggered by human development activities such as the construction and expansion of road networks.Road verges serve as important habitats and corridors for the distribution of invasive alien plant species(IAPS)between geographically distant habitats.However,the trajectory of plant invasion and the data regarding the impact of roads on IAPS distribution are relatively poor in Nepal.Here,we surveyed two road types(main roads and feeder road)in the Middle Mountain region of central Nepal in order to investigate how different road types are driving the dispersal of IAPS along road verges and the adjacent natural habitats.Systematic sampling was conducted at ca 2.5 km intervals along the roads.At each sampling site,paired plots(25 m×4 m)were sampled:one adjacent to and along the road,and another 20 m away and parallel to it in the interior habitat.Our results revealed that the main road verges had a higher cover(33%)and a larger number of IAPS(14 species)than the feeder road(25%;10 species).The IAPS cover and richness were significantly higher along verges than in the adjacent interior habitats for both road types,indicating that roads are contributing as corridors for the dispersal of IAPS in the Middle Mountain areas of central Nepal.Further,elevation,tree canopy,and disturbances(grazing/mowing/trampling)were found to be the key factors that determine spatial distribution of IAPS along road verges.We emphasize that regular monitoring of vegetation along the road verges can help with the early detection and control of potential IAPS in the region before they become problematic.展开更多
Herein,we developed the invasive plant-derived biochar (IPB) functionalized with CaAl-LDH at five mass ratios using a physical mixture method,assessed their adsorption perform for Eu(Ⅲ),and explored the relative mech...Herein,we developed the invasive plant-derived biochar (IPB) functionalized with CaAl-LDH at five mass ratios using a physical mixture method,assessed their adsorption perform for Eu(Ⅲ),and explored the relative mechanisms.Results show that the IPB successfully loaded CaAl-LDH in five composites and their Eu(Ⅲ) sorption affinities were strongly affected by solution p H,contact time,temperature,and the mass ratio of LDH and IPB.All the sorpiton process for Eu(Ⅲ) occurred on the heterogeneous surface of five composites and the boundary layer diffusion limited the chemical sorption rate.Interestingly,the CaAl-LDH/IPB composite with high ratio of IPB had higher sorption capacity than the one with high ratio of LDH due to larger porosity of the former.Three mechanisms containing ion exchange between Al and Eu ions,surface complexation with carboxyl-and oxygen-containing functional groups,and precipitation were involved in the Eu(Ⅲ) sorption,but the dominant sorption mechanism for each CaAl-LDH/IPB composite differed with different mass ratio of CaAl-LDH and IPB.In composite with more IPB (e.g.,CaAl-LDH/IPB-13),both ion exchange and surface complexes dominated the sorption process and the intensity of Eu^3+ was identified with the one of Eu2O3.Whereas in composites with high LDH,ion exchange dominated the sorption and the intensity of Eu^3+ was obviously higher than the one of Eu_2O_3.This research will provide a new perspective for the application of the LDH/biochar materials.展开更多
Solidago canadensis,a perennial Compositae plant originating from North America,was introduced into China as a horticultural plant in 1935.Under natural condi-tions,S.canadensis allocates large amounts of energy to se...Solidago canadensis,a perennial Compositae plant originating from North America,was introduced into China as a horticultural plant in 1935.Under natural condi-tions,S.canadensis allocates large amounts of energy to sexual reproduction and produces many seeds,which reflects an r-strategy with high seed number and small seed size.In addition,naturalized populations have a great capacity to grow clonally with underground stems.S.canadensis has become an invasive weed in eastern China,and has caused serious damages to agricultural production and ecosystems in several provinces in China.In order to understand the reproductive characteristics of S.canadensis and effectively control its spread,we examined soil conditions,seed charac-teristics,seed germination and the capacity for asexual reproduction in different plant parts.We investigated the population dispersion of S.canadensis in fixed sites for three years,and analyzed the seasonal dynamics of the morphological parameters of the underground parts and the caloric values of different organs of S.canadensis.We also compared differences in the root systems of S.canadensis and composite exotic weeds.The following results were obtained:1)Under natural conditions,the germination season of S.canadensis lasts from March to October,with a peak from April to May.Vegetative growth and asexual reproduction are especially vigorous during summer due to high temperatures and soil drought stress.On the other hand,the rainy season proves suitable for seed germination.Most S.canadensis flower between September and January,and fruit in late October.A mature plant can produce about 20000 seeds.The mean weight of 1000 seeds ranges from 0.045 g to 0.050 g,and the mean seed moisture content ranges from 60%to 80%.The light-winged seeds disperse readily by air,water,vehicles,human activity or through livestock.2)S.canadensis seeds have a wide tolerance for different values of pH,salinity and soil moisture.The mean percent germination of seeds is 30%under suitable conditions.The results of seed germination under various environmental stresses and investigation of soil conditions indicate that well-aerated,slightly acidic soils with low salinity are suitable for the growth of S.canadensis.Additionally,S.canadensis has a high tolerance for contamination by heavy metal elements including Zn,Cu and Pb,but has low accumulation coefficients for these elements.3)S.canadensis reproduces asexually via underground rhizomes and nodes on the stem base to recruit new individuals,and in plants that experience mechanical damage,this repro-ductive strategy is used to produce clonal shoots.The capacity for asexual reproduction among different plant parts rank as follows:underground parts>stem-base(20 cm)>stem-base(30 cm)>stem-base(45 cm)>stem.Further,with increasing mechanical damage,the quantity of shoots produced by the plant decreases.4)The morphological parameters of the root system of S.canadensis including length,surface area,volume,and average diameter are greater than for composite exotic weeds.These parameters indicate that S.canadensis has the physiological potential to widely invade China.5)The aboveground growth rate and most of the underground morphological parameters vary remarkably among the seasons,with a peak normally occurring in September.In August,a fraction of the energy in leaves and stems is allocated underground to increase fine root growth and water uptake during hot weather.Additionally,the seasonal dynamics of the underground morphological parameters and the caloric values of different organs of S.canadensis enhance its reproductive ability.Based on the results above,we conclude that S.canadensis has great invasive potential in China.We suggest that urgent measures should be taken to control its further spread,and to minimize its impact on local plant diversity.展开更多
Galinsona parviflora(Asteraceae)is a wide-spread annual weed that is invasive,colonizing new ground where it is able to persist.We studied the bio-mass structure of the G.parviflora population at the module level by u...Galinsona parviflora(Asteraceae)is a wide-spread annual weed that is invasive,colonizing new ground where it is able to persist.We studied the bio-mass structure of the G.parviflora population at the module level by using the methods of field plot invest-igation and weighing at 10 sample plots.Modular bio-mass was calculated and used for analysis of relation-ships between various modules.The results show that there was a positive correlation between plant height and modular biomass,between stem biomass and root biomass,stem biomass and capitulum biomass,above-ground biomass and underground biomass,and lastly,stem biomass and leaf biomass.The preferred model which measured all the relationships was a power function model with absolute coefficients(R2)ranging from 0.6303 to 0.9782.展开更多
River restoration activities are challenging for the native vegetation and the colonization process. The development of invasive alien plant species (IAS) as well as the development of the pioneer vegetation cover and...River restoration activities are challenging for the native vegetation and the colonization process. The development of invasive alien plant species (IAS) as well as the development of the pioneer vegetation cover and seed bank were observed in one year prior to construction of a new river bed and within the first two years after construction, along the downstream section of the river Traisen in Austria. One year after completion of the new river channel, the occurrence of IAS above ground decreased while the occurrence of target species increased. Furthermore, no seeds of IAS were detected in the new river bed as a result of proper management of soil movement. Despite the positive impact on the abundance of IAS, the restoration project of the river Traisen shows that the fact that such a restoration activity is a disturbance event must be taken into consideration already during the planning process. Supporting the competitiveness of native plant species is an important tool for reducing the danger of establishment of invasive alien species.展开更多
Land-use and plant invasion influence biodiversity.Understanding the effects of land-use types and invasive plants on the ecosystem is crucial for better management and the development of strategic plans for increasin...Land-use and plant invasion influence biodiversity.Understanding the effects of land-use types and invasive plants on the ecosystem is crucial for better management and the development of strategic plans for increasing biodiversity in Jeju Island,Korea,a designated Biosphere Reserve by the United Nations Education,Scientific,and Cultural Organization.The effect of the most dominant invasive exotic species,Hypochaeris radicata,on the four land-use types of Jeju Island was investigated.Plant composition,soil characteristics,and plant diversity among four land-use types(cropland,green space,neglected land,and residential)were compared.Among the land-use types,croplands had the most diverse plant composition and the highest richness in exotic and native plant species.Croplands,such as tangerine orchards,which are widely distributed throughout Jeju Island,showed the highest plant diversity because of medium intensity disturbance caused by weed removal.The relative cover of H.radicata did not differ between land-use types.However,H.radicata invasion was negatively related with plant species richness,making this invasive species a threat to the biodiversity of native herbs present in land-use areas.H.radicata adapts to areas with a broad range of soil properties and a variety of land-use types.Therefore,it is crucial to monitor land-use types and patterns of plant invasion to guide the implementation of consistent management and conservation strategies for maintaining ecosystem integrity of the transformed habitat in Jeju Island.展开更多
Bidens pilosa is recognized as one of the major invasive plants in China.Its invasion has been associated with significant losses in agriculture,forestry,husbandry,and biodiversity.Soil ecosystems play an important ro...Bidens pilosa is recognized as one of the major invasive plants in China.Its invasion has been associated with significant losses in agriculture,forestry,husbandry,and biodiversity.Soil ecosystems play an important role in alien plant invasion.Microorganisms within the soil act as intermediaries between plants and soil ecological functions,playing a role in regulating soil enzyme activities and nutrient dynamics.Understanding the interactions between invasive plants,soil microorganisms,and soil ecological processes is vital for managing and mitigating the impacts of invasive species on the environment.In this study,we conducted a systematic analysis focusing on B.pilosa and Setaria viridis,a common native companion plant in the invaded area.To simulate the invasion process of B.pilosa,we constructed homogeneous plots consisting of B.pilosa and S.viridis grown separately as monocultures,as well as in mixtures.The rhizosphere and bulk soils were collected from the alien plant B.pilosa and the native plant S.viridis.In order to focus on the soil ecological functional mechanisms that contribute to the successful invasion of B.pilosa,we analyzed the effects of B.pilosa on the composition of soil microbial communities and soil ecological functions.The results showed that the biomass of B.pilosa increased by 27.51% and that of S.viridis was significantly reduced by 66.56%.The organic matter contents in the bulk and rhizosphere soils of B.pilosa were approximately 1.30 times those in the native plant soils.The TN and NO_(3)^(-)contents in the rhizosphere soil of B.pilosa were 1.30 to 2.71 times those in the native plant soils.The activities of acid phosphatase,alkaline phosphatase,and urease in the rhizosphere soil of B.pilosa were 1.98-2.25 times higher than in the native plant soils.Using high-throughput sequencing of the16S rRNA gene,we found that B.pilosa altered the composition of the soil microbial community.Specifically,many genera in Actinobacteria and Proteobacteria were enriched in B.pilosa soils.Further correlation analyses verified that these genera had significantly positive relationships with soil nutrients and enzyme activities.Plant biomass,soil p H,and the contents of organic matter,TN,NO_(3)^(-),TP,AP,TK,and AK were the main factors affecting soil microbial communities.This study showed that the invasion of B.pilosa led to significant alterations in the composition of the soil microbial communities.These changes were closely linked to modifications in plant traits as well as soil physical and chemical properties.Some microbial species related to C,N and P cycling were enriched in the soil invaded by B.pilosa.These findings provide additional support for the hypothesis of soil-microbe feedback in the successful invasion of alien plants.They also offer insights into the ecological mechanism by which soil microbes contribute to the successful invasion of B.pilosa.Overall,our research contributes to a better understanding of the complex interactions between invasive plants,soil microbial communities,and ecosystem dynamics.展开更多
Terrestrial invasive plant species continue to wreak havoc on a global economic and ecological scale. With the advent of climate change and pending future catastrophes, the spread of resilient invasive plants will onl...Terrestrial invasive plant species continue to wreak havoc on a global economic and ecological scale. With the advent of climate change and pending future catastrophes, the spread of resilient invasive plants will only increase exponentially. Here, the search continues for a better understanding of the below-ground microbially driven mechanisms involved in plant invasion where other above-ground mechanisms have been exhausted. Microbes govern the world around us and interact with every living and non-living facet of the world. To reinforce the important underpinnings of the role of microorganisms in plant invasion, a systematic review of recently published articles was undertaken. Using the ScienceDirect database, five (5) search queries were used to generate 1221 research articles. After a two-step reduction was made based on relevance of the articles, a final total of 59 articles were retrieved. An additional 18 relevant articles were also assessed through the PubMed database for analysis to account for other invasive plants. Thirty-seven (37) invasive species were investigated where soil physiochemical and microbial community structure changes were most prevalent (32% & 39% respectively) while enhanced mutualism, allelopathy and pathogen accumulation were reported less (16%, 10% & 3% respectively). In all invasive species assessed, the impact on plant invasion and inability of the native plants to compete was due to specific microbial associations of the invasive plant or disruption of the soil microbial community. This microbial community shift coincided with changes in physiochemical properties of the soil and the subsequent negative soil feedback for native plants. There is still an expanding potential for the use of biocontrol agents to aid restoration once the underpinnings of biotic resistance and enemy release are understood in a microbial and physiochemical context. The active and functional microbial community structure of the invasive plant rhizosphere and adjacent soil in its native and non-native region can offer a better inference of how they can be controlled using novel-below ground biocontrol methods.展开更多
Background: Natural resources within and around urban landscapes are under increasing pressure from ongoing urbanisation, and management efforts aimed at ensuring the sustainable provision of ecosystem services(ES) ar...Background: Natural resources within and around urban landscapes are under increasing pressure from ongoing urbanisation, and management efforts aimed at ensuring the sustainable provision of ecosystem services(ES) are an important response. Given the limited resources available for assessing urban ES in many cities, practical approaches for integrating ES in decision-making process are needed.Methods: We apply remote sensing techniques(integrating LiDAR data with high-resolution multispectral imagery)and combined these with supplementary spatial data to develop a replicable approach for assessing the role of urban vegetation(including invasive alien plants) in providing ES and ecosystem disservices(EDS). We identify areas denoting potential management trade-offs based on the spatial distribution of ES and EDS using a local-scale case study in the city of Cape Town, South Africa. Situated within a global biodiversity hotspot, Cape Town must contend with widespread invasions of alien plants(especially trees and shrubs) along with complex socio-political challenges. This represents a useful system to examine the challenges in managing ES and EDS in the context of urban plant invasions.Results: Areas of high ES provision(for example carbon sequestration, shade and visual amenity) are characterized by the presence of large trees. However, many of these areas also result in numerous EDS due to invasions of alien trees and shrubs – particularly along rivers, in wetlands and along the urban edge where tall alien trees have established and spread into the natural vegetation(for example increased water consumption, increased fire risk and reduced soil quality). This suggests significant trade-offs regarding the management of species and the ES and EDS they provide.Conclusions: The approach applied here can be used to provide recommendations and to guide city planners and managers to fine-tune management interventions at local scales to maximise the provision of ES.展开更多
Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. ...Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.展开更多
Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Austral...Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Australia. This investigation aimed to evaluate and compare germination behavior and occurrence of polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from the short pod form exhibited significantly higher germination rates and higher occurrence of polyembryony than those from the long pod form. Seeds from the long pod form did not germinate at the lowest temperature of 10/20°C;in contrast, those of the short pod form germinated under this condition, albeit at a lower rate. Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed form in Australia, while the long pod form is confined to a few localities. The results have implication in predicting future ranges of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed.展开更多
Invasive species have profound negative impacts on native ranges.Unraveling the mechanisms employed by invasive plant species is crucial to controlling invasions.One important approach that invasive plants use to outc...Invasive species have profound negative impacts on native ranges.Unraveling the mechanisms employed by invasive plant species is crucial to controlling invasions.One important approach that invasive plants use to outcompete native plants is to disrupt mutualistic interactions between native roots and mycorrhizal fungi.However,it remains unclear how differences in the competitive ability of invasive plants affect native plant associations with mycorrhizae.Here,we examined how a native plant,Xanthium strumarium,responds to invasive plants that differed in competitive abilities(i.e.,as represented by aboveground plant biomass)by measuring changes in root nitrogen concentration(root nutrient acquisition)and mycorrhizal colonization rate.We found that both root nitrogen concentration and mycorrhizal colonization rate in the native plant were reduced by invasive plants.The change in mycorrhizal colonization rate of the native plant was negatively correlated with both aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant in monocultures relative to mixed plantings.In contrast,the change in root nitrogen concentration of the native plant was positively correlated with aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant.When we compared the changes in mycorrhizal colonization rate and root nitrogen concentration in the native plant grown in monocultures with those of native plants grown with invasive plants,we observed a significant tradeoff.Our study shows that invasive plants can suppress native plants by reducing root nutrient acquisition rather than by disrupting symbiotic mycorrhizal associations,a novel finding likely attributable to a low dependence of the native plant on mycorrhizal fungi.展开更多
To reduce the harms of plant invasion,the risk assessment for biological invasion of exotic species( including intentionally introduced species and accidentally introduced species) is particularly important. Through d...To reduce the harms of plant invasion,the risk assessment for biological invasion of exotic species( including intentionally introduced species and accidentally introduced species) is particularly important. Through data review,investigation research and expert consultation,risk assessment system and standard for exotic species invasion in Zhengzhou region was established. Risk of Praxelis clematidea was assessed,in order to provide a reference for possible biological invasion of exotic plants in Zhengzhou.展开更多
Recent trends in globalization,human mobility surge and global trade aggravated the expansion of alien species introduction leading to invasion by alien plants compounded by climate change.The ability to predict the s...Recent trends in globalization,human mobility surge and global trade aggravated the expansion of alien species introduction leading to invasion by alien plants compounded by climate change.The ability to predict the spread of invasive species within the context of climate change holds significance for accurately identifying vulnerable regions and formulating strategies to contain their wide proliferation and invasion.Anthropogenic activities and recent climate change scenarios increased the risk of Chromolaena odorata invasion and habitat expansion in Mizoram.To forecast its current distribution and habitat suitability amidst climatic alterations in Mizoram,a MaxEnt-driven habitat suitability model was deployed using the default parameters.The resultant model exhibited that the current spatial range of C.odorata occupies 15.37%of geographical areas deemed suitable for varying degrees of invasion.Projections for 2050 and 2070 anticipated an expansion of suitable habitats up to 34.37%of the geographical area of Mizoram,specifically under RCP 2.6 in 2070 in comparison with its present distribution.Currently,the distributional range of C.odorata in Mizoram spans from lower(450 m)to mid elevational ranges up to 1700 meters,with limited presence at higher altitudes.However,the habitat suitability model extrapolates that climate changes will elevate the invasion risk posed by C.odorata across Mizoram,particularly in the North-Western and Central regions.The projection of further territorial expansion and an upward shift in altitudinal range in the future underscores the urgency of instating robust management measures to pre-empt the impact of C.odorata invasion.This study recommends the imperative nature of effective C.odorata management,particularly during the initial stages of invasion.展开更多
基金Supported by National Key R&D Program(2020YFF0305905-06)Science and Technology Project of Hebei Academy of Sciences(22112)Key Discipline Project of Hebei Academy of Sciences(491-0401-YBN-DDH4).
文摘[Objectives]The paper was to investigate the garden greenbelt in 30 sample plots such as parks,roads,communities,etc.in Shijiazhuang City.[Methods]The species,abundance and frequency of weeds in the greenbelt of public gardens were recorded through point-line-surface investigation,and typical plants were sampled.[Results]There were 56 species of alien invasive plants in garden greenbelts of Shijiazhuang City,belonging to 44 genera and 20 families.In terms of life form,herbaceous plants were absolutely dominant,accounting for 92.8%of the total.The most alien invasive plants were native to America,accounting for 66.1%of the total.In terms of introduction path,the plants introduced artificially and unintentionally accounted for almost half.The species and quantity of alien invasive plants were related to the size of greenbelt area,the length of the build time of the surveyed plot,the composition structure of greenbelt and the level of green management and protection.There was larger distribution of alien invasive plants in the sample plots with large greenbelt area,long build time,herbaceous-dominated greenbelt and low level of green management and protection.Among the 56 alien invasive plants,3 plants were toxic.From the perspective of invasiveness,the alien invasive plants in the garden greenbelt of Shijiazhuang City could be divided into 5 levels:invasive alien species of malignant consequences,invasive alien species of severe consequences,invasive alien species of partial consequences,invasive alien species of average consequences,and invasive alien species to be observed.[Conclusions]This study will provide a reference for the prevention and control of alien plant invasion,and lay a foundation for the prevention and control of existing invasive plants.
基金Supported by the Basic Ability Improvement Project for Young and Middle Aged Teachers in Guangxi(KY2016YB421)the Project for Backbone Teachers of Baise University in 2013(210203009)
文摘According to the field survey of alien invasive plants of Jinziling,there were 23 kinds of alien invasive plants in the scenic spot.Species with the comprehensive dominance degree higher than 10% were as follows: six kinds of Asteraceae: Bidens pilosa,Aster subulatus,Ageratum conyzoides,Conyzai canadens,Parthenium hysterophorus,and Conyza sumatrensis; two kinds of Gramineae: Axonopus compressu,Eleusine indica; two kinds of convolvere: Ipomoea nil,Ipomoea purpurea; two kinds of Fabaceae: Cassiae tora,Medicago hispida; one kind of Verbenaceae: Lantana camara; one kind of Euphorbiaceae: Euphorbia hirta.In total,there were 14 kinds of alien invasive plants.In this survey,the dominant species of invasive plants were obtained by statistical analysis of the composition and distribution of the invasive plants,and the invasion trend was predicted,so as to take effective and economical management and control measures.
基金This study was supported by the National Natural Science Foundation of China(Nos.31770449,31270465)Fundamental Research Funds for the Central Universities(2662020YLPY016,2662016PY064).
文摘A key scientific challenge relating to the threat of invasive plants on agriculture at the region level is to understand their adaptation and evolution in functional traits.Leaf functional traits,related to growth and resource utilization,might lead to adaptation of invasive plants to the geographical barriers(region or elevation).In the field experiment,we discussed the effects of region and elevation on leaf functional traits on invasive plant Erigeron annuus in farmland habitats in China.We compared leaf size,coefficient of variation(CV)of leaf traits,and fluctuating asymmetry(FA)of E.annuus from three regions(east vs.center vs.west)and two leaf types(vegetative vs.reproductive leaf),and from nine elevations(980-2100 m)in the west region of China.Our results indicated region and leaf type influenced leaf functional traits,and leaf size was significantly higher and CV of leaf traits and FA in reproductive leaves were significantly lower in the east region than in the west and center regions.Elevation and leaf type affected leaf functional traits,and leaf size was significantly higher and CV of leaf traits in reproductive leaves were significantly lower in moderate elevation.E.annuus has higher leaf size and developmental stability(lower CV and FA)in the eastern region due to the longer adaptation period.Therefore,leaf functional traits play an important role in the adaptation of different longitudes and elevations.It can also facilitate the understanding of the invasiveness and adaptation of leaf traits of invasive plants in the agricultural ecosystem during their spread process in China.
基金financially supported by the National Natural Science Foundation of China(Grant number:32071661)。
文摘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.
基金Supported by National Natural Science Foundation of China(31900271,32160086)Key Project of Guizhou Basic Research Program(QKHJC[2019]1455)Central Government Supporting Local Science and Technology Development Fund Project(QKZYD[2021]4010).
文摘[Objectives]The paper was to investigate and assess the species,distribution and hazard status of invasive alien plants on the campus of Tongren University.[Methods]A survey was conducted using line survey method,and the risk assessment index system of invasive alien plants was established by analytic hierarchy process(AHP).[Results]There were 11 species of invasive alien plants on the campus of Tongren University,belonging to 8 genera and 5 families.There were 6 species of invasive alien plants belonging to Asteraceae,accounting for 54.55%of the total.In terms of the origin of invasive plants,most of them were native to North America and Europe,accounting for 27.27%of the total.In terms of harmful level,there were no high-risk invasive plants on the campus of Tongren University,but Alternanthera philoxeroides had the highest score and was the most harmful.[Conclusions]The present situation of alien plant invasion on the campus of Tongren University is closely related to the ecological environment of the campus.It is suggested to strengthen the management of campus plants,focus on the prevention and control of A.philoxeroides,and carry out regular investigation of invasive alien plants on campus to ensure the ecological safety of the campus.
基金funded by the National Natural Science Foundation of China(32072490)the National Key R&D Program of China(2021YFC2600100 and2021YFC2600101)the Agricultural Science and Technology Innovation Program,China。
文摘Mikania micrantha is a fast-growing global invasive weed species that causes severe damage to natural ecosystems and very large economic losses of forest and crop production.It has advantages in photosynthesis,including a similar net photosynthetic rate as C4 plants and a higher carbon fixation capacity.We used a combination of genomics and transcriptomics approaches to study the evolutionary mechanisms and circadian expression patterns of M.micrantha.In M.micrantha,16 positive selection genes focused on photoreaction and utilization of photoassimilates.In different tissues,98.1%of the genes associated with photoresponse had high expression in stems,and more than half of the genes of the C4 cycle had higher expression in stems than in leaves.In stomatal opening and closing,2 genes of carbonic anhydrase(CAs)had higher expression at 18:00 than at 8:00,and the slow anion channel 1(SLAC1)and high-leaf-temperature 1 kinase(HT1)genes were expressed at low levels at 18:00.In addition,genes associated with photosynthesis had higher expression levels at 7:00 and 17:00.We hypothesized that M.micrantha may undergo photosynthesis in the stem and flower organs and that some stomata of the leaves were opening at night by CO_(2)signals.In addition,its evolution may attenuate photoinhibition at high light intensities,and enhance more efficient of photosynthesis during low light intensity.And the tissue-specific photosynthetic types and different diurnal pattern of photosynthetic-related genes may contribute to its rapid colonization of new habitats of M.micrantha.
文摘Biological invasion is triggered by human development activities such as the construction and expansion of road networks.Road verges serve as important habitats and corridors for the distribution of invasive alien plant species(IAPS)between geographically distant habitats.However,the trajectory of plant invasion and the data regarding the impact of roads on IAPS distribution are relatively poor in Nepal.Here,we surveyed two road types(main roads and feeder road)in the Middle Mountain region of central Nepal in order to investigate how different road types are driving the dispersal of IAPS along road verges and the adjacent natural habitats.Systematic sampling was conducted at ca 2.5 km intervals along the roads.At each sampling site,paired plots(25 m×4 m)were sampled:one adjacent to and along the road,and another 20 m away and parallel to it in the interior habitat.Our results revealed that the main road verges had a higher cover(33%)and a larger number of IAPS(14 species)than the feeder road(25%;10 species).The IAPS cover and richness were significantly higher along verges than in the adjacent interior habitats for both road types,indicating that roads are contributing as corridors for the dispersal of IAPS in the Middle Mountain areas of central Nepal.Further,elevation,tree canopy,and disturbances(grazing/mowing/trampling)were found to be the key factors that determine spatial distribution of IAPS along road verges.We emphasize that regular monitoring of vegetation along the road verges can help with the early detection and control of potential IAPS in the region before they become problematic.
基金supported by the National Nature Science Foundation of China (Nos.31700476,21777102)。
文摘Herein,we developed the invasive plant-derived biochar (IPB) functionalized with CaAl-LDH at five mass ratios using a physical mixture method,assessed their adsorption perform for Eu(Ⅲ),and explored the relative mechanisms.Results show that the IPB successfully loaded CaAl-LDH in five composites and their Eu(Ⅲ) sorption affinities were strongly affected by solution p H,contact time,temperature,and the mass ratio of LDH and IPB.All the sorpiton process for Eu(Ⅲ) occurred on the heterogeneous surface of five composites and the boundary layer diffusion limited the chemical sorption rate.Interestingly,the CaAl-LDH/IPB composite with high ratio of IPB had higher sorption capacity than the one with high ratio of LDH due to larger porosity of the former.Three mechanisms containing ion exchange between Al and Eu ions,surface complexation with carboxyl-and oxygen-containing functional groups,and precipitation were involved in the Eu(Ⅲ) sorption,but the dominant sorption mechanism for each CaAl-LDH/IPB composite differed with different mass ratio of CaAl-LDH and IPB.In composite with more IPB (e.g.,CaAl-LDH/IPB-13),both ion exchange and surface complexes dominated the sorption process and the intensity of Eu^3+ was identified with the one of Eu2O3.Whereas in composites with high LDH,ion exchange dominated the sorption and the intensity of Eu^3+ was obviously higher than the one of Eu_2O_3.This research will provide a new perspective for the application of the LDH/biochar materials.
基金This work was supported by the Science and Technology Development Foundation of Shanghai High School(No.04DB17,06ZZ20)the Natural Science Foundation of Zhejiang Province(No.Y505018).
文摘Solidago canadensis,a perennial Compositae plant originating from North America,was introduced into China as a horticultural plant in 1935.Under natural condi-tions,S.canadensis allocates large amounts of energy to sexual reproduction and produces many seeds,which reflects an r-strategy with high seed number and small seed size.In addition,naturalized populations have a great capacity to grow clonally with underground stems.S.canadensis has become an invasive weed in eastern China,and has caused serious damages to agricultural production and ecosystems in several provinces in China.In order to understand the reproductive characteristics of S.canadensis and effectively control its spread,we examined soil conditions,seed charac-teristics,seed germination and the capacity for asexual reproduction in different plant parts.We investigated the population dispersion of S.canadensis in fixed sites for three years,and analyzed the seasonal dynamics of the morphological parameters of the underground parts and the caloric values of different organs of S.canadensis.We also compared differences in the root systems of S.canadensis and composite exotic weeds.The following results were obtained:1)Under natural conditions,the germination season of S.canadensis lasts from March to October,with a peak from April to May.Vegetative growth and asexual reproduction are especially vigorous during summer due to high temperatures and soil drought stress.On the other hand,the rainy season proves suitable for seed germination.Most S.canadensis flower between September and January,and fruit in late October.A mature plant can produce about 20000 seeds.The mean weight of 1000 seeds ranges from 0.045 g to 0.050 g,and the mean seed moisture content ranges from 60%to 80%.The light-winged seeds disperse readily by air,water,vehicles,human activity or through livestock.2)S.canadensis seeds have a wide tolerance for different values of pH,salinity and soil moisture.The mean percent germination of seeds is 30%under suitable conditions.The results of seed germination under various environmental stresses and investigation of soil conditions indicate that well-aerated,slightly acidic soils with low salinity are suitable for the growth of S.canadensis.Additionally,S.canadensis has a high tolerance for contamination by heavy metal elements including Zn,Cu and Pb,but has low accumulation coefficients for these elements.3)S.canadensis reproduces asexually via underground rhizomes and nodes on the stem base to recruit new individuals,and in plants that experience mechanical damage,this repro-ductive strategy is used to produce clonal shoots.The capacity for asexual reproduction among different plant parts rank as follows:underground parts>stem-base(20 cm)>stem-base(30 cm)>stem-base(45 cm)>stem.Further,with increasing mechanical damage,the quantity of shoots produced by the plant decreases.4)The morphological parameters of the root system of S.canadensis including length,surface area,volume,and average diameter are greater than for composite exotic weeds.These parameters indicate that S.canadensis has the physiological potential to widely invade China.5)The aboveground growth rate and most of the underground morphological parameters vary remarkably among the seasons,with a peak normally occurring in September.In August,a fraction of the energy in leaves and stems is allocated underground to increase fine root growth and water uptake during hot weather.Additionally,the seasonal dynamics of the underground morphological parameters and the caloric values of different organs of S.canadensis enhance its reproductive ability.Based on the results above,we conclude that S.canadensis has great invasive potential in China.We suggest that urgent measures should be taken to control its further spread,and to minimize its impact on local plant diversity.
基金The research was funded by Liaoning Province Science and Technology Plan Project(No.2004214001)Liaoning Province Education Department Science and Technology Research Project(No.2005275)。
文摘Galinsona parviflora(Asteraceae)is a wide-spread annual weed that is invasive,colonizing new ground where it is able to persist.We studied the bio-mass structure of the G.parviflora population at the module level by using the methods of field plot invest-igation and weighing at 10 sample plots.Modular bio-mass was calculated and used for analysis of relation-ships between various modules.The results show that there was a positive correlation between plant height and modular biomass,between stem biomass and root biomass,stem biomass and capitulum biomass,above-ground biomass and underground biomass,and lastly,stem biomass and leaf biomass.The preferred model which measured all the relationships was a power function model with absolute coefficients(R2)ranging from 0.6303 to 0.9782.
文摘River restoration activities are challenging for the native vegetation and the colonization process. The development of invasive alien plant species (IAS) as well as the development of the pioneer vegetation cover and seed bank were observed in one year prior to construction of a new river bed and within the first two years after construction, along the downstream section of the river Traisen in Austria. One year after completion of the new river channel, the occurrence of IAS above ground decreased while the occurrence of target species increased. Furthermore, no seeds of IAS were detected in the new river bed as a result of proper management of soil movement. Despite the positive impact on the abundance of IAS, the restoration project of the river Traisen shows that the fact that such a restoration activity is a disturbance event must be taken into consideration already during the planning process. Supporting the competitiveness of native plant species is an important tool for reducing the danger of establishment of invasive alien species.
基金This research is supported by National Research Foundation of Korea(No:2019R1I1A2A03061067).
文摘Land-use and plant invasion influence biodiversity.Understanding the effects of land-use types and invasive plants on the ecosystem is crucial for better management and the development of strategic plans for increasing biodiversity in Jeju Island,Korea,a designated Biosphere Reserve by the United Nations Education,Scientific,and Cultural Organization.The effect of the most dominant invasive exotic species,Hypochaeris radicata,on the four land-use types of Jeju Island was investigated.Plant composition,soil characteristics,and plant diversity among four land-use types(cropland,green space,neglected land,and residential)were compared.Among the land-use types,croplands had the most diverse plant composition and the highest richness in exotic and native plant species.Croplands,such as tangerine orchards,which are widely distributed throughout Jeju Island,showed the highest plant diversity because of medium intensity disturbance caused by weed removal.The relative cover of H.radicata did not differ between land-use types.However,H.radicata invasion was negatively related with plant species richness,making this invasive species a threat to the biodiversity of native herbs present in land-use areas.H.radicata adapts to areas with a broad range of soil properties and a variety of land-use types.Therefore,it is crucial to monitor land-use types and patterns of plant invasion to guide the implementation of consistent management and conservation strategies for maintaining ecosystem integrity of the transformed habitat in Jeju Island.
基金funded by the National Key R&D Program of China(2022YFC2601100,2021YFD1400100 and 2021YFC2600400)the National Natural Science Foundation of China(42207162)。
文摘Bidens pilosa is recognized as one of the major invasive plants in China.Its invasion has been associated with significant losses in agriculture,forestry,husbandry,and biodiversity.Soil ecosystems play an important role in alien plant invasion.Microorganisms within the soil act as intermediaries between plants and soil ecological functions,playing a role in regulating soil enzyme activities and nutrient dynamics.Understanding the interactions between invasive plants,soil microorganisms,and soil ecological processes is vital for managing and mitigating the impacts of invasive species on the environment.In this study,we conducted a systematic analysis focusing on B.pilosa and Setaria viridis,a common native companion plant in the invaded area.To simulate the invasion process of B.pilosa,we constructed homogeneous plots consisting of B.pilosa and S.viridis grown separately as monocultures,as well as in mixtures.The rhizosphere and bulk soils were collected from the alien plant B.pilosa and the native plant S.viridis.In order to focus on the soil ecological functional mechanisms that contribute to the successful invasion of B.pilosa,we analyzed the effects of B.pilosa on the composition of soil microbial communities and soil ecological functions.The results showed that the biomass of B.pilosa increased by 27.51% and that of S.viridis was significantly reduced by 66.56%.The organic matter contents in the bulk and rhizosphere soils of B.pilosa were approximately 1.30 times those in the native plant soils.The TN and NO_(3)^(-)contents in the rhizosphere soil of B.pilosa were 1.30 to 2.71 times those in the native plant soils.The activities of acid phosphatase,alkaline phosphatase,and urease in the rhizosphere soil of B.pilosa were 1.98-2.25 times higher than in the native plant soils.Using high-throughput sequencing of the16S rRNA gene,we found that B.pilosa altered the composition of the soil microbial community.Specifically,many genera in Actinobacteria and Proteobacteria were enriched in B.pilosa soils.Further correlation analyses verified that these genera had significantly positive relationships with soil nutrients and enzyme activities.Plant biomass,soil p H,and the contents of organic matter,TN,NO_(3)^(-),TP,AP,TK,and AK were the main factors affecting soil microbial communities.This study showed that the invasion of B.pilosa led to significant alterations in the composition of the soil microbial communities.These changes were closely linked to modifications in plant traits as well as soil physical and chemical properties.Some microbial species related to C,N and P cycling were enriched in the soil invaded by B.pilosa.These findings provide additional support for the hypothesis of soil-microbe feedback in the successful invasion of alien plants.They also offer insights into the ecological mechanism by which soil microbes contribute to the successful invasion of B.pilosa.Overall,our research contributes to a better understanding of the complex interactions between invasive plants,soil microbial communities,and ecosystem dynamics.
文摘Terrestrial invasive plant species continue to wreak havoc on a global economic and ecological scale. With the advent of climate change and pending future catastrophes, the spread of resilient invasive plants will only increase exponentially. Here, the search continues for a better understanding of the below-ground microbially driven mechanisms involved in plant invasion where other above-ground mechanisms have been exhausted. Microbes govern the world around us and interact with every living and non-living facet of the world. To reinforce the important underpinnings of the role of microorganisms in plant invasion, a systematic review of recently published articles was undertaken. Using the ScienceDirect database, five (5) search queries were used to generate 1221 research articles. After a two-step reduction was made based on relevance of the articles, a final total of 59 articles were retrieved. An additional 18 relevant articles were also assessed through the PubMed database for analysis to account for other invasive plants. Thirty-seven (37) invasive species were investigated where soil physiochemical and microbial community structure changes were most prevalent (32% & 39% respectively) while enhanced mutualism, allelopathy and pathogen accumulation were reported less (16%, 10% & 3% respectively). In all invasive species assessed, the impact on plant invasion and inability of the native plants to compete was due to specific microbial associations of the invasive plant or disruption of the soil microbial community. This microbial community shift coincided with changes in physiochemical properties of the soil and the subsequent negative soil feedback for native plants. There is still an expanding potential for the use of biocontrol agents to aid restoration once the underpinnings of biotic resistance and enemy release are understood in a microbial and physiochemical context. The active and functional microbial community structure of the invasive plant rhizosphere and adjacent soil in its native and non-native region can offer a better inference of how they can be controlled using novel-below ground biocontrol methods.
基金Funding for this work was provided by the DST-NRF Centre of Excellence for Invasion Biology and the Working for Water Programme through their collaborative research project on “Integrated Management of invasive alien species in South Africa”the National Research Foundation,South Africa(grant85417 to DMR)
文摘Background: Natural resources within and around urban landscapes are under increasing pressure from ongoing urbanisation, and management efforts aimed at ensuring the sustainable provision of ecosystem services(ES) are an important response. Given the limited resources available for assessing urban ES in many cities, practical approaches for integrating ES in decision-making process are needed.Methods: We apply remote sensing techniques(integrating LiDAR data with high-resolution multispectral imagery)and combined these with supplementary spatial data to develop a replicable approach for assessing the role of urban vegetation(including invasive alien plants) in providing ES and ecosystem disservices(EDS). We identify areas denoting potential management trade-offs based on the spatial distribution of ES and EDS using a local-scale case study in the city of Cape Town, South Africa. Situated within a global biodiversity hotspot, Cape Town must contend with widespread invasions of alien plants(especially trees and shrubs) along with complex socio-political challenges. This represents a useful system to examine the challenges in managing ES and EDS in the context of urban plant invasions.Results: Areas of high ES provision(for example carbon sequestration, shade and visual amenity) are characterized by the presence of large trees. However, many of these areas also result in numerous EDS due to invasions of alien trees and shrubs – particularly along rivers, in wetlands and along the urban edge where tall alien trees have established and spread into the natural vegetation(for example increased water consumption, increased fire risk and reduced soil quality). This suggests significant trade-offs regarding the management of species and the ES and EDS they provide.Conclusions: The approach applied here can be used to provide recommendations and to guide city planners and managers to fine-tune management interventions at local scales to maximise the provision of ES.
文摘Invasive plant species may significantly alter plant species community composition and structure thereby negatively impacting on ecosystem services. Their impacts on plant communities may be both direct and indirect. The direct effects may include a reduction in the abundance and diversity of palatable plant species that constitute important forage for livestock, wildlife, and medicines for the local communities. Declines in ecosystem resilience are of the notable indirect effects of invasive species. The aim of this study was to assess the impacts of a plant species, copper leaf (<em>Acalypha fruticosa</em>) on floral diversity and abundance at Chemeron, Baringo County in Kenya. The study was guided by three questions: What is the plant composition in terms of grasses, herbs, shrubs, and trees in the study area? Are there any variations in plant abundance between the two sites (sites with and without <em>Acalypha fruticosa</em>)? Are there variations in plant species diversity between the two study sites? Two sites (one with <em>A. fruticosa</em> and another two without this invasive species) were selected within the Chemeron Research Centre. Two belt transects measuring 100 m × 20 m on each site were laid parallel to each other. Plant samples were collected from five 1 m × 1 m quadrats that were laid at intervals of 20 m. The plant species or specimens were identified to the species level using available taxonomic keys. Various indices including Shannon-Wiener (<em>H</em>’), Evenness Index, Richness Index and Simpson’s Index of Diversity Index (SDI) were calculated. All the diversity, richness and evenness indices were considerably higher in the site without <em>A. fruticosa</em> compared to that where this invasive species was present. Higher <em>H’</em> (3.14 to 3.21) and SDI (0.93 to 0.94) values were noted in sites without the invasive species compared to <em>H</em>’ (2.11 to 2.20) and SDI (0.77 to 0.85) in sites with <em>A. fruticosa</em> present. Out of the 47 plant species identified, 39 and 20 of them occurred in the site without and with <em>A. fruticosa</em>, respectively. Further, there were more grasses (<em>Aristida keniensis</em>, <em>Cynodon dactylon</em>, <em>Brachiaria lucrantha</em>, <em>Eragrostis racemosa</em>, and <em>Enteropogon macrostachyus</em>) in the site without <em>A. fruticosa</em> compared to that with the invasive plant. The plants were also more evenly distributed in the site without <em>A. fruticosa</em> compared to that where the invasive plant was present. We conclude that <em>A. fruticosa</em> has a significant effect on plant species abundance and diversity as well as distribution. Its removal created a favourable environment for the growth of a variety of grasses. We therefore recommend to the agro-pastoralists and rangeland managers that <em>A. fruticosa</em> be mechanically removed by uprooting from grazing lands so as to increase forage availability and quality in the rangelands of South-Baringo.
文摘Cat’s claw creeper vine, Dolichandra unguis-cati (L.) Lohmann (syn. Macfadyena unguis-cati (L.) Gentry), is a major environmental weed in Australia. Two forms (“long” and “short” pod) of the weed occur in Australia. This investigation aimed to evaluate and compare germination behavior and occurrence of polyembryony (production of multiple seedlings from a single seed) in the two forms of the weed. Seeds were germinated in growth chambers set to 10/20°C, 15/25°C, 20/30°C, 30/45°C and 25°C, representing ambient temperature conditions of the region. Germination and polyembryony were monitored over a period of 12 weeks. For all the treatments in this study, seeds from the short pod form exhibited significantly higher germination rates and higher occurrence of polyembryony than those from the long pod form. Seeds from the long pod form did not germinate at the lowest temperature of 10/20°C;in contrast, those of the short pod form germinated under this condition, albeit at a lower rate. Results from this study could explain why the short pod form of D. unguis-cati is the more widely distributed form in Australia, while the long pod form is confined to a few localities. The results have implication in predicting future ranges of both forms of the invasive D. unguis-cati, as well as inform management decisions for control of the weed.
基金supported by the National Natural Science Foundation of China(31870522,32171746 and 32171662)the Scientific Research Foundation of Henan Agricultural University(30500854),Research Funds for overseas returnee in Henan Province,China.
文摘Invasive species have profound negative impacts on native ranges.Unraveling the mechanisms employed by invasive plant species is crucial to controlling invasions.One important approach that invasive plants use to outcompete native plants is to disrupt mutualistic interactions between native roots and mycorrhizal fungi.However,it remains unclear how differences in the competitive ability of invasive plants affect native plant associations with mycorrhizae.Here,we examined how a native plant,Xanthium strumarium,responds to invasive plants that differed in competitive abilities(i.e.,as represented by aboveground plant biomass)by measuring changes in root nitrogen concentration(root nutrient acquisition)and mycorrhizal colonization rate.We found that both root nitrogen concentration and mycorrhizal colonization rate in the native plant were reduced by invasive plants.The change in mycorrhizal colonization rate of the native plant was negatively correlated with both aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant in monocultures relative to mixed plantings.In contrast,the change in root nitrogen concentration of the native plant was positively correlated with aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant.When we compared the changes in mycorrhizal colonization rate and root nitrogen concentration in the native plant grown in monocultures with those of native plants grown with invasive plants,we observed a significant tradeoff.Our study shows that invasive plants can suppress native plants by reducing root nutrient acquisition rather than by disrupting symbiotic mycorrhizal associations,a novel finding likely attributable to a low dependence of the native plant on mycorrhizal fungi.
基金Supported by New Century Education and Teaching Reform and Talent Cultivation Project of Local Colleges and Universities in Zhengzhou(2013,ZZJZ-A6003)
文摘To reduce the harms of plant invasion,the risk assessment for biological invasion of exotic species( including intentionally introduced species and accidentally introduced species) is particularly important. Through data review,investigation research and expert consultation,risk assessment system and standard for exotic species invasion in Zhengzhou region was established. Risk of Praxelis clematidea was assessed,in order to provide a reference for possible biological invasion of exotic plants in Zhengzhou.
基金the Ministry of Environment,Forest and Climate Change,Government of India for financial support through the National Mission on Himalaya Studies (Project NMHS2017/LG/01/475).
文摘Recent trends in globalization,human mobility surge and global trade aggravated the expansion of alien species introduction leading to invasion by alien plants compounded by climate change.The ability to predict the spread of invasive species within the context of climate change holds significance for accurately identifying vulnerable regions and formulating strategies to contain their wide proliferation and invasion.Anthropogenic activities and recent climate change scenarios increased the risk of Chromolaena odorata invasion and habitat expansion in Mizoram.To forecast its current distribution and habitat suitability amidst climatic alterations in Mizoram,a MaxEnt-driven habitat suitability model was deployed using the default parameters.The resultant model exhibited that the current spatial range of C.odorata occupies 15.37%of geographical areas deemed suitable for varying degrees of invasion.Projections for 2050 and 2070 anticipated an expansion of suitable habitats up to 34.37%of the geographical area of Mizoram,specifically under RCP 2.6 in 2070 in comparison with its present distribution.Currently,the distributional range of C.odorata in Mizoram spans from lower(450 m)to mid elevational ranges up to 1700 meters,with limited presence at higher altitudes.However,the habitat suitability model extrapolates that climate changes will elevate the invasion risk posed by C.odorata across Mizoram,particularly in the North-Western and Central regions.The projection of further territorial expansion and an upward shift in altitudinal range in the future underscores the urgency of instating robust management measures to pre-empt the impact of C.odorata invasion.This study recommends the imperative nature of effective C.odorata management,particularly during the initial stages of invasion.
