Impacts of road on plant invasions in the Middle Mountain region of central Nepal

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.

A fine-scale assessment of the ecosystem service-disservice dichotomy in the context of urban ecosystems affected by alien plant invasions

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.

Detecting the distribution of and public attitudes to charismatic alien species based on media coverage

Charismatic species are often reported by the media,providing information for detecting population status and public perception.To identify the number and distribution of free-living Black Swan(Cygnus atratus),a charismatic alien species in Chinese mainland and to detect the public and the media attitudes to the species,we analyzed the reports and emotional tendency from media coverage in 2000-2022 using manual reading,crawler extraction and latent Dirichlet allocation.A total of 6654 Black Swans were reported at 711 sites,including 147 individuals at 30 nature reserves.Successful breeding was reported at one-fourth of the total sites,including five nature reserves.The proportion of positive emotional tendency to Black Swans was overwhelming in the reports and was higher than that to alien species in general,suggesting that the public and the media are unaware of the risk of biological invasion.Effective management of invasive species requires the media clarifies the invasion risk of charismatic alien species.Promoting the unity between the harmfulness of abstract concept of alien species and the charisma of a specific alien species among the public help effective management.

Herbivore and native plant diversity synergistically resist alien plant invasion regardless of nutrient conditions

Alien plant invasion success can be inhibited by two key biotic factors:native herbivores and plant diversity.However,few studies have experimentally tested whether these factors interact to synergistically resist invasion success,especially factoring in changing global environments(e.g.nutrient enrichment).Here we tested how the synergy between native herbivores and plant diversity affects alien plant invasion success in various nutrient conditions.For this purpose,we exposed alien plant species in potmesocosms to different levels of native plant diversity(4 vs.8 species),native generalist herbivores,and high and low soil nutrient levels.We found that generalist herbivores preferred alien plants to native plants,inhibiting invasion success in a native community.This inhibition was amplified by highly diverse native communities.Further,the amplified effect between herbivory and native plant diversity was independent of nutrient conditions.Our results suggest that a higher diversity of native communities can strengthen the resistance of native generalist herbivores to alien plant invasions by enhancing herbivory tolerance.The synergistic effect remains in force in nutrient-enriched habitats that are always invaded by alien plant species.Our results shed light on the effective control of plant invasions using multi-trophic means,even in the face of future global changes.

Current Status, Influence and Countermeasure of Biological Invasion on Ecological Security in China

The concept, pathways and the present status of biological invasion in China are reviewed in the paper, and the effect of biological invasion on ecological security is also introduced. On this basis, the measures such as establishing early-warning mechanism, strengthening the management of invasive species and quarantine of alien species, establishing scientific system of introduction and improving people awareness are proposed to control the invasion of alien species, so as to ensure the ecological security in china.

Biology,invasion and management of the agricultural invader:Fall armyworm,Spodoptera frugiperda(Lepidoptera:Noctuidae)

The fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),is native to the Americas.It has rapidly invaded 47 African countries and 18 Asian countries since the first detection of invasion into Nigeria and Ghana in 2016.It is regarded as a super pest based on its host range(at least 353 host plants),its inherent ability to survive in a wide range of habitats,its strong migration ability,high fecundity,rapid development of resistance to insecticides/viruses and its gluttonous characteristics.The inherently superior biological characteristics of FAW contribute to its invasiveness.Integrated pest management(IPM)of FAW has relied on multiple applications of monitoring and scouting,agricultural control,chemical pesticides,viral insecticides,sex attractants,bio-control agents(parasitoids,predators and entomopathogens)and botanicals.Knowledge gaps remain to be filled to:(1)understand the invasive mechanisms of S.frugiperda;(2)understand how to prevent its further spread and(3)provide better management strategies.This review summarizes the biological characters of FAW,their association with its invasiveness and IPM strategies,which may provide further insights for future management.

Biodiversity and Invasibility: Distribution Patterns of Invasive Plant Species in the Himalayas, Nepal

Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.

Potential Distribution of Alien Invasive Species and Risk Assessment:a Case Study of Erwinia amylovora in China

Alien invasive species represent a severe risk to biodiversity and economy, as in the case of fire blight （Erwinia amylovora）, a bacterial disease that originated in North America, which may be released into new locations by means of fruit trade. On the basis of the knowledge of Erwinia amylovora＇s biophysical characteristics and environmental data, the geographic information system （GIS） has been applied to determine areas where Erwinia amylovora can potentially invade China. Temperature and precipitation, during the blossoming period, are considered to be two critical factors affecting the Erwinia amylovora＇s suitable climatic zones. This spatial modeling approach was validated from a case study in Europe, where the occurrence of Erwinia amylovora has been proven. The model prediction agreed with the occurrence of the bacteria recorded in Europe, and the same procedure has been applied to produce a potential establishment area in China＇s two preferential apple cultivation regions, Bohai Bay region and Huangtu Altiplano region. It has been found that areas belonging to the high-risk category are more or less the main apple producing areas, accounting for their great economic importance in China. This methodology provides an initial baseline for assessment, prevention, and management of alien species that may become invasive under certain environmental conditions. In addition, this modeling approach provides a tool for policy makers to use, in making decisions on management practices where alien species are involved.

A method for estimating vegetation change over time and space

Plant diversity is used as an indicator of the well-being of vegetation and ecological systems. Human activities and global change drive vegetation change in composition and competition of species through plant invasions and replacement of existing species on a given scale. However, species diversity indices do not consider the effects of invasions on the diversity value and on the functions of ecosystems. On the other hand, the existing methods for diversity index can not be used directly for cross-scale evaluation of vegetation data. Therefore, we proposed a 3-dimensional model derived from the logistic equation for estimating vegetation change, using native and non-native plant diversity. The two variables, based on the current and the theoretical maximum diversity of native plants on a given scale, and the result of the model are relative values without units, and are therefore scale-independent. Hence, this method developed can be used directly for cross-scale evaluations of vegetation data, and indirectly for estimating ecosystem or environmental change.

Use of non-timber forest products from invasive alien Prosopis species(mesquite) and native trees in South Africa: implications for management

Background: Prosopis species have been introduced to many areas outside their native range to provide benefits to local communities. Several Prosopis species and their hybrids(hereafter "mesquite") have, however, become naturalised and invasive and now generate substantial costs. Management options are limited because of the complex conflicts of interest regarding benefits and costs. Management policies and strategies must take account of such conflicts, but further insights are needed on the dimensions of uses and impacts before such information can be usefully applied. Current policy in South Africa allows for the growth and use of mesquite in one province,but not in others where its control is mandatory. We report on a study to quantify the direct use and perceptions of non-timber forest products(NTFPs) from mesquite and native trees in South Africa.Methods: Semi-structures household interviews were conducted with various stakeholder groups to identify what tree products are used, to ascertain amounts used as well as to gauge perceptions of natural resource use between different tree species and use over time.Results: The direct household use value of native trees was higher than that of mesquite, and local stakeholders attached greater value to products from native trees than from mesquite. Therefore, native trees are and will still be preferentially harvested, and mesquite is unlikely to offer protection to native species by providing an alternative source of products. Mesquite pods do, however, provide valuable additional resources(fodder and medicinal products). The use of both native trees and mesquite is decreasing as the incomes of poorer households rise and as alternative energy sources become available. The benefits and reliance on mesquite are not as high as previously assumed and the impacts from mesquite invasions create large problems for local communities.Conclusion: This study provides further evidence that the impacts of mesquite exceed the benefits, lending support for a policy to reduce negative impacts.

Impacts of invasive Iris pseudacorus L.(yellow flag) establishing in an abandoned urban pond on native semi-wetland vegetation

Iris pseudacorus L., intentionally introduced in Japan as an ornamental plant and to improve aquatic environments, has been declared a noxious species in the Invasive Alien Species Act of Japan due to the suspected high ecological risks to the local species and ecosystems. Although prompt responses to I. pseudacorus have been sought to conserve local biodiversity, knowledge about its invasiveness is lacking. Here, we report the relationship between the establishment of I. pseudacorus and floristic changes in semi-wetland vegetation of an abandoned urban pond(Aoike), Nara City, Nara Prepecture, Japan. In total, 64 vascular plants were recorded in the pond, of which 50 were native species, seven were naturalized non-native, and seven were invasive species. On the other hand, most of these vascular plants(42 species) were grassland species and only several aquatic plants(10 species) were found in this study pond. The number of vascular plant species decreased significantly at quadrats with a coverage of I. pseudacorus above 50%. In addition, tendencies of lower number of native species and concomitant higher number of invasive species were found with increasing coverage of I. pseudacorus. From these results, we suggest that it is important to preferentially manage sites where the coverage of I. pseudacorus is above 50%, in order to preserve the local biodiversity. Additionally, as recommended in the literature, it is essential that the cut reproductive organs are kept submerged under deep water for an effective control of I. pseudacorus.

Abundance of White-fronted Parrots and diet of an urban parrot assemblage(Aves:Psittaciformes)in a green Neotropical city

Urban ecosystems are evolutionarily recent novel environments acting as biodiversity filters.Psittacidae birds are considered successful urban adapters mainly due to their generalist feeding and opportunistic behavior,allowing them to occupy environments from cold temperate to dry xeric areas.Therefore,it is important to understand how these species interact in the urban environment.We studied the interannual(2013–2016)abundance of the White-fronted Parrot(Amazona albifrons)in the Neotropical cities of Xalapa and Coatepec,in Central Veracruz,México.Additionally,we studied the feeding ecology during 13 months of 6 parrot species detected in the city of Xalapa.The abundance of the White-fronted Parrot was significantly higher in Xalapa than in Coatepec,and it was homogeneous across years.Non-native plants represented 30–41%of Psittacidae diets in Xalapa,where seeds were the most commonly consumed resource.We recorded the highest Psittacidae species richness and highest diet overlap among species by the end of the dry season(April–May).The White-fronted Parrot had the highest plant richness in its diet,followed by the Monk Parakeet(Myiopsitta monachus)and the Green Parakeet(Psittacara holochlorus);yet,the White-fronted Parrot had a specialized diet dominated by two plant species(Grevillea robusta and Ficus aurea).The diet overlap among the three above-mentioned parrot species was not significantly different to a null model,where the White-fronted Parrot and the Monk Parakeet overlapped during the months of February,April,June,and September.The White-fronted Parrot is an urban adapter that has successfully expanded its geographic range via natural means and by human activities.The invasive Monk Parakeet is currently restricted to one park in Xalapa,and it has remained in that stage for many years(i.e.,pre-expansion phase).Exotic plant species in Xalapa represent∼55%of the woody vegetation,some of which have longer flowering and fruiting periods that may have aided the successful establishment of parrot species in urban environments.

Experience of Complex Application of BW Convention （2004） by the Example of the Port Novorossiysk

The pioneer technical policy carried out by Federal State Institution ＂Novorossiysk Maritime Port Administration＂ in mutual cooperation with the Southern Scientific Centre of Russian Academy of Sciences on control and management of ballast waters and ecosystem monitoring of marine environment in areas of ballast water discharge provides the task of complex approach for minimization of risk of introduction of biologically negative invaders by marine transport and preservation of biodiversity of the Black Sea.

cDNA Cloning of Heat Shock Protein Genes and Their Expression in an Indigenous Cryptic Species of the Whitefly Bemisia tabaci Complex from China

Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects,and heat shock proteins（Hsps）play important roles in the temperature adaptation of various organisms.To better understand the temperature tolerance of the indigenous ZHJ2-biotype of whitefly Bemisia tabaci species complex,we obtained complete cDNA sequences for hsp90,hsp70,and hsp20 and analyzed their expression profiles under different high temperature treatments by real-time quantitative polymerase chain reaction.The high temperature tolerance of B.tabaci ZHJ2-biotype was determined by survival rate after exposure to different high temperatures for 1 h.The results showed that after 41°C heat-shock treatment for 1 h,the survival rates of ZHJ2 adults declined significantly and the estimated temperature required to cause 50% mortality（LT50）is 42.85°C for 1 h.Temperatures for onset（Ton）or maximal（Tmax）induction of hsps expression in B.tabaci ZHJ2-biotype were 35 and 39°C（or 41°C）.Compared with previous studies,indigenous ZHJ2-biotype exhibits lower heat temperature stress tolerance and Ton（or Tmax）than the invasive B-biotype.

Geographical Variation and Influencing Factors of Spartina alterniflora Expansion Rate in Coastal China

Biological invasion poses a huge threat to ecological security.Spartina alterniflora was introduced into China in 1979,and its arrival corresponded with negative effects on native ecosystems.To explore geographical variation of its expansion rate in coastal China,we selected 43 S.alterniflora sites from Tianjin Coastal New Area to Beihai.The area expansion rate,expansion rate paralleling and vertical to the shoreline were analysed based on Landsat images and field survey in 2015.Simple Ocean Data Assimilation(SODA)and climate data were collected to statistically analyse the influential factors of expansion rate.Results showed that significant difference of S.alterniflora area expansion rate among different latitude zones(P<0.01),increasing from 6.08%at southern(21°N–23°N)to 19.87% in Bohai Bay(37°N–39°N)along latitude gradient.There was a significant difference in expansion rate vertical to shoreline in different latitude zones(P<0.01)with the largest occurring in Bohai Bay(256m/yr,37°N–39°N),and showed an decreasing tendency gradually from north to south.No significant difference and latitudinal clines in expansion rate paralleling to shoreline were observed.Expansion rate had significant negative correlation with mean seawater temperature,the lowest seawater temperature,current zonal velocity and meridional velocity and presented a reducing trend as these biotic factors increased;however,they were not significantly correlated with the highest seawater temperature and mean seawater salinity.We identified significant correlations between expansion rate and annual mean temperature,the lowest temperature in January and annual precipitation,but there was little correlation with annual diurnal difference in temperature and the highest temperature in July.The rapid expansion rate in high-latitude China demonstrated a higher risk of potential invasion in the north;dynamic monitoring and control management should be established as soon as possible.

Factors affecting the geographical distribution of invasive species in China

Frequent international trade has accelerated alien species invasion. However, data on the distribution of invasive species after their introduction and research on the factors that determine their geographical distribution are lacking. This study analyzed the distributional trends of invasive species in China and the drivers for such trends, by identifying the effect of international trade from a dynamic analysis of 13 main invasive insect pests in three time periods - before China’s reform and opening up in 1978, from 1979 to 2001, and after China’s accession to the World Trade Organization in 2001. The results showed that the abundance of invasive species gradually decreased from south to north and from southeast coast to inland. Guangdong(442 species) and Yunnan(404 species) provinces have the highest abundance of invasive species. Among the 13 key invasive insects investigated, 3, 10 and 13 occurred chronologically in the three periods, and invaded 7, 28 and 34 provinces, respectively. Alien pests are found to invade China through Xinjiang, the Bohai Rim and the southeast. Value of imports was a strong predictor of the number of invasive species in China, and followed by temperature heterogeneity, in explaining the richness pattern of invasive animal, plants and insects, but not that of microorganisms. This study provides a scientific basis for furthering international quarantine and effective invasive species control.

Changes in Soil Biota Resulting from Growth of the Invasive Weed, Ambrosia artemisiifolia L.(Compositae), Enhance Its Success and Reduce Growth of Co-Occurring Plants

Exotic plant invasion presents a serious threat to native ecosystem structure and function. Little is known about the role of soil microbial communities in facilitating or resisting the spread of invasive plants into native communities. The purpose of this research is to understand how the invasive annual plant Ambrosia artemisiifolia L. facilitates its competition capacity through changing the structure and function of soil microbial communities. The soil characteristics of different areas invaded by A. artemisiifolia were examined. Greenhouse experiments were designed to assess the effect of A. artemisiifolia invasion-induced changes of soil biota on co-occurring plant growth, and on the interactions between A. artemisiifolia and three co-occurring plant species. The results showed that the soil organic C content was the highest in heavily invaded sites, the lowest in native plant sites, and intermediate in newly invaded sites. Soil available N, P and K concentrations in heavily invaded site were 2.4, 1.9 and 1.7 times higher than those in native plant soil, respectively. Soil pH decreased as A. artemisiifolia invasion intensity increased, and was lower in invaded sites（heavily invaded and newly invaded） than in native plant sites. The soil microbial community structure was clearly separated in the three types of sites, and A. artemisiifolia invasion increased anaerobe, sulfate-reducing bacteria and actinomycete abundance. Soil biota of invaded sites inhibits growth of co-occurring plants（Galinsoga parvifloraCav., Medicago sativa L. and Setaria plicata（Lam.） T. Cooke.） compared to soil biota from un-invaded sites, but facilitates A. artemisiifolia growth and competition with co-occurring plants. A. artemisiifolia biomass was 50-130% greater when competing with three co-occurring plants, compared to single-species competition only（invasion by A. artemisiifolia alone）, in heavily invaded soil. Results of the present study indicated that A. artemisiifolia invasion alters the soil microbial community in a way that favors itself while inhibiting native plant species, with measurable effects on performance of co-occurring plants.

Effect of pine wood nematode invasion on pine community functions in the Pinghu region, Zhejiang Province, eastern China

In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.

Relative importance of biological and human-associated factors for alien plant invasions in Hokkaido, Japan

Aims The invasion success of alien plants is strongly affected by both biological and human-associated factors.Evaluation of the rela-tive contribution of each factor is important not only for the further understanding of invasion processes but also for the better manage-ment of invasion risk,particularly in protected areas of high con-servation priority.Here,we quantified the relative importance of species biological traits and association with a human activity,i.e.agriculture,in explaining the invasion success of alien plants across the entire region and in protected areas in Hokkaido,Japan.Methods As a quantitative measure of invasion success,the distribution ex-tent of naturalized populations across the entire prefecture and in protected areas was calculated for 63 alien species with equal residence time based on species occurrence records at a spatial resolution of 5-km mesh grid units.For each species,we identi-fied seven biological traits(seed mass,dispersal mode,maximum plant height,capability of vegetative reproduction,flowering start time and period and life span)and two human-associated factors(introduction purpose and cultivation frequency for agricultural use).Cultivation frequency was determined based on the frequency of seed-sowing in pastures:(1)not sown,(2)accidentally sown as a seed contaminant and(3)intentionally sown for commercial cul-tivation.The importance of biological traits and human-associated factors in explaining the distribution extent was determined using an information-theoretic approach.Important Findings In explaining the distribution extent across the entire prefecture,species biological traits and human-associated factors showed comparable importance;cultivation frequency exhibited the high-est importance value closely followed by seed mass,maximum height and flowering period.In contrast,when focusing on pro-tected areas,human association was more important than bio-logical traits,as indicated by the greatest importance of cultivation frequency and much lower values for most biological traits.The results demonstrated that species biological traits and human as-sociation almost equally contributed to invasion success across the entire region,while invasions into protected areas were more attributable to human association than to biological traits.We highlight that the control of propagule pressure associated with artificial cultivation may be key to preventing further invasions into protected areas.

Research Progress on the Invasion Mechanism of Erigeron annuus

Erigeron annuus(L.)Pers.,an alien species,is widely distributed in most areas of China.It was included in the third batch of invasive alien species list by the Ministry of Ecology and Environment of China,and it is a first-level malignant invasive plant.Due to its great reproducibility with a mass of seeds,power adaptability to the external environment and strong allelopathy,it has highly invasive and adaptability,and has affected the development of the agriculture and forestry,the diversity of local species and the ecosystem.In this paper,we summarized the current invasion situation,invasion and adaptation mechanism of E.annuus,and prospected further research on E.annuus invasion mechanism,hoping to provide a reference for realizing its effective management.