Community Invasibility Research Articles

Interplay between native plant performance and environment shapes resistance to aquatic plant invasion

Abstract In the limited number of studies on biotic resistance in freshwater ecosystems, experimental studies have supported that native plants play a role in resisting exotic plant invasion, but field observations have often reported positive relationships between exotic and native plant richness. To determine the reasons for the lack of evidence supporting biotic resistance in field observations, we surveyed the richness, biomass and coverage of exotic and native aquatic plants in 2801 quadrats at 287 sites in various freshwater ecosystems of China and examined the impacts of scale and environmental factors on the relationships between native and exotic plant richness and performance. At both the site and quadrat scales, we observed a positive correlation between the richness of exotic and native plants. However, at the quadrat scale, high native plant richness was associated with a reduction in the biomass of exotic emergent and floating plants as well as the biomass of exotic submerged plants in low‐nutrient water bodies. An increase in native plant performance, a metric that integrates the biomass and coverage of native plants, was associated with a decrease in both the richness and biomass of exotic plants at both scales. Furthermore, with increasing native plant performance at the quadrat scale, the richness of exotic plants declined more strongly in low‐nutrient water bodies than in high‐nutrient water bodies, and the decline in the biomass of exotic emergent and floating plants was more severe in shallow water than in deep water. Synthesis. Our results indicate that native plant performance is more important than richness for resistance to invasion in freshwater ecosystems, and the strength of biotic resistance is related to environmental factors. This study highlights the importance of environmental variables and multiple native community features and invasibility metrics in field observational studies of invasion.

Interpreting the shifts in forest structure, plant community composition, diversity, and functional identity by using remote sensing-derived wildfire severity

BackgroundWildfires are increasingly impacting ecosystems worldwide especially in temperate dry habitats, often interplaying with other global changes (e.g., alien plant invasions). Understanding the ecological consequences of wildfires is crucial for effective conservation and management strategies. The aim of this study was to investigate the impacts of wildfire severity on plant community (both the canopy trees and herbaceous layer) and alien plant invasion, combining field observations and remotely sensed data.We conducted an observational study in the Karst forests (North-East Italy) 1 year after the large wildfire which affected the area in 2022. We assessed the impact through 35 field plots (200 m2 each) distributed among different fire severity (i.e., the loss of organic matter) classes assessed using the differenced normalized burn ratio (dNBR) calculated from satellite images. In each plot, tree species, diameter, vitality, resprouting capacity, and seedling density were measured. In addition, herb species richness (taxonomical diversity) was quantified, and plant cover was visually estimated. Functional diversity was also assessed considering six functional traits retrieved from databases.ResultsSome woody species (e.g., Quercus pubescens) showed a higher resistance to the fire (i.e., lower mortality rate), while others showed a higher resilience (i.e., recovery after fire through resprouting or seedlings, e.g., Cotinus coggygria). The transition to a shrub-dominated community (i.e., Cotinus coggygria) where fire severity was the highest underlines the dynamic nature of the post-fire succession. We detected a significant variation in the herbaceous plant community composition, diversity, and functional identity (i.e., community-weighted mean of trait) along the fire severity gradient. In particular, high-fire severity areas exhibited higher species richness compared to low-severity or unburned areas. Total alien plant cover increased with fire severity, while native cover remained constant. We also found shifts in species that enhance traits related to germination potential and growth strategy.ConclusionsOur results highlight the vulnerability of the forest stands to an increase in wildfire severity, resulting in significant mortality and changes in tree community structure. This study contributes to the understanding of ecological processes after wildfires using a novel remote sensing approach in a temperate forest, emphasizing the need for conservation strategies aimed at mitigating high severity wildfires.

Invasive annual grasses destabilize plant communities in a northern mixed‐grass prairie

AbstractTemporal community stability, here defined as temporal mean divided by temporal SD, plays an important role in predicting certain ecosystem services. However, temporal stability can change with invasion, with greater abundances of invasive species potentially having greater impacts on native community stability. The exact consequences of invasion for temporal stability are unclear and, in part, depend on the particular metric of stability measured. In rangeland ecosystems, predicable forage is important for livestock production but can be threatened by invasion. Therefore, using an observational field study conducted over three years in Wyoming, we assessed which metrics of plant community stability were altered by invasion and whether those effects were mediated by two environmental variables (light and soil moisture). Bromus arvensis and Bromus tectorum are two invasive annual weeds found across US rangelands, including the northern mixed‐grass prairies of Wyoming. We established plots along natural invasion blocks of B. arvensis and B. tectorum abundance and collected plant species composition data over three growing seasons. We tested associations between seven different metrics of plant community stability and invasion by B. arvensis and B. tectorum. We found that species turnover increases with invasion by both species, while stability of forb (both brome species), C4 grass (B. arvensis only), and C3 grass (B. tectorum only) cover decreases with invasion. All metrics of stability associated with invasion supported the hypothesis of a destabilizing effect of invasion on the native plant community. Further, we found that light and soil moisture did mediate some associations between stability and invasion. Overall, our results align with previous work suggesting that invasive annual bromes can lead to decreased native plant stability, which has important implications for forage production and, thus, food security.

Functional traits of exotic submerged macrophytes mediate diversity-invasibility relationship in freshwater communities under eutrophication

Plant diversity may respond differently in terms of whether it can drive plant invasions in freshwater ecosystem. Linkages and interactions between diversity and invasibility have not been clearly resolved, and it is unclear how nutrient enrichment (e.g., eutrophication) will affect this relationship. As a key predictor of plant growth, the ability of functional traits to mediate trade-offs in the diversity-invasibility relationship is unknown. Here, we conducted a series of experiments to determine the role of exotic plant functional traits in the diversity-invasibility relationship of submerged macrophyte communities under eutrophication. We selected common native and exotic submerged macrophytes in the subtropics to construct different diverse submerged macrophyte communities to simulate invasion. Meanwhile, to test the adaptability and importance of functional traits, we experimentally verified the differences in functional traits between exotic and native species. Our results showed a positive correlation between native plant diversity and community invasibility. Moreover, the invader's performance was predominantly determined by functional traits of exotic species, such as plant biomass and tissue nutrients, which were significantly altered by species diversity. Furthermore, our results suggested that functional traits contribute significantly more to the invasiveness of exotic submerged macrophytes than the other factors to which they are subjected. Plant functional traits can mediate the diversity–invasibility relationship because of the higher intrinsic dominance of exotic submerged macrophyte species. In summary, our study revealed diversity-invasibility relationship in submerged macrophyte communities and highlighted functional traits as key drivers of invasion of high-risk exotic submerged macrophyte species. Although previous studies have elucidated the importance of functional trait studies for plant invasions, our study provides the only current evidence demonstrating the important role of invaders' functional traits in mediating the diversity-invasibility relationship. This novel perspective offers valuable insights into the management and control of invasive aquatic plants.

Wretched Lives in a Westernised African Country: the Obstacles Towards Development of Communities in Botswana

This paper is necessitated to advance the narrative that due to westernisation of the economy of Botswana, which is an African country that is glorified for its economic success, rural development has been grossly compromised. The infiltration of westernisation has led to the undermining and removal of economic activities that were pivotal for the development of rural communities. Due to westernisation the economic, political and social performance of rural communities were taken as not germane for western development and consequently discarded by the newly independent government. The paper promulgates the view that communities in Botswana through rural development could improve their living conditions economically, politically, technologically and socially, but are submerged in poverty because of the strong believe that indigenous knowledge was an impediment to economic, political, technological and social progress. The imperialist forces have persistently and aggressively presented western knowledge as a panacea for rural development despite its inappropriateness in some cases. The rural areas that cherished indigenous knowledge systems that were tested and utilised over a period of time, allowed the communities the opportunities to perfect them and pass them from generation to generation. The westernisation process has denied the rural communities in Botswana to promote the advancement of what sustained them before they got colonised and Christened. The discarding of traditional schools for instances, incapacitated the rural communities, as they lost the system that enhanced skills transfer, promoted industriousness and self-efficacy amongst the recipients. The importation of western religions detached the rural areas in Botswana from the traditional values that were inculcated on young adults from generation to generation. The traditional leaders got disempowered, leading to their non-participation on matters of community importance, such as land distribution and control of other valuable resources such as the rapacious annexation of livestock from rural communities by urban livestock rustlers. The paper takes particular interest in the role the traditional leaders used to play in fighting poverty amongst the communities through protecting resources from unbridled greed by politicians and foreigners. The invasion of communities through the enforcement of inherited western laws disempowered traditional leaders by placing them under full control of politicians and foreign corporations. The independence of Botswana meant the replacing of colonisers with western trained leaders, who invidiously upheld western values, with the deliberate effort to transform communities into becoming Eurocentric.

Plant interactions can lead to emergent relationships between plant community diversity, productivity and vulnerability to invasion

Understanding what makes a community vulnerable to invasion is integral to the successful management of invasive species. Our understanding of how characteristics of resident plant interactions, such as the network architecture of interactions, can affect the invasibility of plant communities is limited. Using a simulation model, we tested how successfully a new plant invader established in communities with different network architectures of species interactions. We also investigated whether species interaction networks lead to relationships between invasibility and other community properties also affected by species interaction networks, such as diversity, species dominance, compositional stability and the productivity of the resident community. We found that higher invasibility strongly related with a lower productivity of the resident community. Plant interaction networks influenced diversity and invasibility in ways that led to complex but clear relationships between the two. Heterospecific interactions that increased diversity tended to decrease invasibility. Negative conspecific interactions always increased diversity and invasibility, but increased invasibility more when they increased diversity less. This study provides new theoretical insights into the effects of plant interaction networks on community invasibility and relationships between diversity and invasibility. Combined with increasing empirical evidence, these insights could have useful implications for the management of invasive plant species.

Impacts of Soil Properties on Species Diversity and Structure in Alternanthera philoxeroides-Invaded and Native Plant Communities.

Soil properties can affect plant population dynamics and the coexistence of native and invasive plants, thus potentially affecting community structure and invasion trends. However, the different impacts of soil physicochemical properties on species diversity and structure in native and invaded plant communities remain unclear. In this study, we established a total of 30 Alternanthera philoxeroides-invaded plots and 30 control plots in an area at the geographical boundary between North and South China. We compared the differences in species composition between the invaded and native plant communities, and we then used the methods of regression analysis, redundancy analysis (RDA), and canonical correspondence analysis (CCA) to examine the impacts of soil physicochemical properties on four α-diversity indices and the species distribution of these two types of communities. We found that A. philoxeroides invasion increased the difference between the importance values of dominant plant species, and the invasion coverage had a negative relationship with the soil-available potassium (R2 = 0.135; p = 0.046) and Patrick richness index (R2 = 0.322; p < 0.001). In the native communities, the species diversity was determined with soil chemical properties, the Patrick richness index, the Simpson dominance index, and the Shannon-Wiener diversity index, which all decreased with the increase in soil pH value, available potassium, organic matter, and ammonium nitrogen. However, in the invaded communities, the species diversity was determined by soil physical properties; the Pielou evenness index increased with increasing non-capillary porosity but decreased with increasing capillary porosity. The determinants of species distribution in the native communities were soil porosity and nitrate nitrogen, while the determinants in the invaded communities were soil bulk density and available potassium. In addition, compared with the native communities, the clustering degree of species distribution in the invaded communities intensified. Our study indicates that species diversity and distribution have significant heterogeneous responses to soil physicochemical properties between A. philoxeroides-invaded and native plant communities. Thus, we need to intensify the monitoring of soil properties in invaded habitats and conduct biotic replacement strategies based on the heterogeneous responses of native and invaded communities to effectively prevent the biotic homogenization that is caused by plant invasions under environmental changes.

Relationship between plant diversity and community stability and invasibility in the heterogeneous landscape of urban habitats undergoing Solidago canadensis invasion

ABSTRACT Background Solidago canadensis has become an invasive species in Chinese cities. Little progress has been made in understanding the relationship between the plant taxonomic diversity and community stability and invasibility of local plant communities during S. canadensis invasion, especially in heterogeneous landscapes. Progress in understanding the relationship between the key functional traits of S. canadensis and its invasion intensity and competitive advantage, especially in heterogeneous landscapes, is also currently limited. Aims We evaluated the relationship between the key functional traits of Solidago canadensis and its invasion intensity in urban ecosystems in eastern China, while taking into consideration the competitive advantages that these traits may confer. Additionally, we quantified the relationship between plant taxonomic diversity and community stability and invasibility by S. canadensis. Methods This study was conducted using cross-site comparisons between vegetation with S. canadensis invasion and those without S. canadensis invasion in nine types of urban ecosystems (cultural and educational research site, farmland wasteland, scenic garden area, industrial district, municipal land, residential area, roadside, urban green space, and wetland waterfront) in eastern China. Results The stem diameter at ground level, leaf shape index, and leaf chlorophyll concentration of S. canadensis were most highly correlated with its invasion intensity and competitive advantage. Community stability was positively correlated with plant diversity and evenness. Both the community invasibility and invasion intensity of S. canadensis were negatively correlated with the number of plant species of the local flora. Community invasibility was mainly influenced by the number of plant species of the local flora. Conclusions The invasion intensity and competitive advantage of S. canadensis may be largely determined by its stem diameter at ground level, leaf shape index, and leaf chlorophyll concentration. Community stability may be largely determined by the plant diversity and evenness (especially evenness) of the local flora. Community invasibility may be largely determined by the number of plant species of the local flora.

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

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

Resistance towards and biotransformation of a Pseudomonas-produced secondary metabolite during community invasion.

The role of antagonistic secondary metabolites produced by Pseudomonas protegens in suppression of soil-borne phytopathogens has been clearly documented. However, their contribution to the ability of P. protegens to establish in soil and rhizosphere microbiomes remains less clear. Here, we use a four-species synthetic community (SynCom) in which individual members are sensitive towards key P. protegens antimicrobial metabolites (DAPG, pyoluteorin, and orfamide A) to determine how antibiotic production contributes to P. protegens community invasion and to identify community traits that counteract the antimicrobial effects. We show that P. protegens readily invades and alters the SynCom composition over time, and that P. protegens establishment requires production of DAPG and pyoluteorin. An orfamide A-deficient mutant of P. protegens invades the community as efficiently as wildtype, and both cause similar perturbations to community composition. Here, we identify the microbial interactions underlying the absence of an orfamide A mediated impact on the otherwise antibiotic-sensitive SynCom member, and show that the cyclic lipopeptide is inactivated and degraded by the combined action of Rhodococcus globerulus D757 and Stenotrophomonas indicatrix D763. Altogether, the demonstration that the synthetic community constrains P. protegens invasion by detoxifying its antibiotics may provide a mechanistic explanation to inconsistencies in biocontrol effectiveness in situ.

Effects of Different Degrees of Xanthium spinosum Invasion on the Invasibility of Plant Communities in the Yili Grassland of Northwest China.

Studying the effects of different degrees of exotic plant invasion on native plants' community structure and plant diversity is essential for evaluating the harm caused to ecosystems by plant invasion. In this study, we investigated the effects of Xanthium spinosum, a widespread invasive species, on plant community species diversity and community stability in the Ili River Valley area of Xinjiang, China, under three invasion levels (no invasion and low, moderate, and heavy invasion), and the competitive advantage index, invasion intensity, and contribution of plant community species diversity to community stability and invasibility were determined for the prickly fungus under different degrees of invasion. The results show that there were significant differences (p < 0.05) in the species diversity and community stability of plant communities caused by different degrees of invasion of X. spinosum. The species diversity and stability of plant communities were negatively correlated with the community invasibility, competitive advantage, and invasion intensity of X. spinosum (p < 0.05); therefore, the competitive advantage and invasion intensity of X. spinosum increase with the increase of its invasion degree. On the contrary, community species diversity and stability decreased with the increase of its invasion degree, ultimately leading to differences in community invasibility under different invasion degrees. The Shannon-Wiener and Simpson's indices were the greatest contributors to community stability and invasibility, respectively. Moderate and heavy levels of invasion by X. spinosum reduced the diversity and stability of local plant communities, increased the invasibility of communities, and substantially affected the structures of plant communities. Therefore, the continued invasion by X. spinosum will have an immeasurable impact on the fragile ecosystems and diversity of indigenous species in Xinjiang. We recommend that this invasive species be controlled and eradicated at the early stages of invasion to prevent further harm.

Effects of grass functional diversity on invasion success by exotic grasses in Cerrado grasslands

Abstract Invasive species pose significant challenges to successful restoration efforts worldwide. A strategy to reduce invasions is to establish communities consisting of species with varied ecological strategies. These strategies typically align along the conservative and plant size axes, and more recently, along a below‐ground collaboration axis. However, we lack understanding of how the diverse ecological strategies of Cerrado grass species, their combinations and their interactions with soil conditions can mitigate invasions. Here, we investigated how native grass communities composed by species with different ecological strategies affect the invasion success in two soil types of abandoned pastures in the Cerrado. Specifically, we tested the hypothesis that greater above‐ and below‐ground functional diversity reduces exotic species invasion. We also evaluated whether the isolated effects of native species on invasion were positive or negative. We installed an experiment with species richness ranging from zero to eight native grass species. In November 2019, we sowed species combinations to create communities composed by species with different ecological strategies. We quantified the above‐ground biomass of exotic species as a measure of invasion. To characterize the species ecological strategies, we measured five functional traits. Functional diversity of maximum height and specific root length (SRL) had the highest predictive power; however, the most parsimonious model included only SRL diversity, which represents the collaboration axis. Native above‐ground biomass was also negatively related to exotic species biomass. Furthermore, invasion was greater in less stressful soil conditions but did not interact with diversity. The effect of native species varied from facilitation to competition, with the annual fast‐growing native species favouring invasion. Synthesis and applications. Our results show that greater functional diversity of combined above‐ and below‐ground traits reduces invasion success, shedding light on an underexplored role of specific root length diversity. The competitive and facilitative effects of different native species highlight the need for careful selection of the species to be used in restoration programmes. Furthermore, the absence of interaction between diversity and soil types highlights the need for an integrated management of the functional composition and edaphic factors to increase resistance to invasion in these Neotropical grass communities.

Microplastics could alter invasive plant community performance and the dominance of Amaranthus palmeri

The increase in alien plant invasions poses a major threat to global biodiversity and ecosystem stability. However, the presence of microplastics (MPs) as an environmental stressor could impact the interactions between invasive and native species in an invasive plant community. Nevertheless, the community alterations and underlying mechanisms resulting from these interactions remain unclear. Herein, we systematically investigated the impacts of polyethylene (PE) and polypropylene (PP) on invasive plant communities invaded by Amaranthus palmeri through soil seed bank. The results illustrated that MPs markedly declined community height and biomass, and altered community structure, low-dose MPs could prominently increase community invasion resistance, but reduced community stability. The niche width and niche overlap of A. palmeri and S. viridis declined when exposed to high-dose MPs, but MPs elicited a significant rise in the niche width of S. salsa. PP had the potential to reduce the diversity of invasive plant community. Structural equation model revealed that PP addition could change soil total phosphorus content, thereby leading to a reduction of the community stability. Our study helps to fill the knowledge gap regarding the effects of MPs on invasive plant communities and provide new perspectives for invasive plant management.

Emerging old folk home trend in developing Asia: case of Pakistan

Purpose The purpose of this study to highlight the changing living patterns in the Pakistani community from joint family to nuclear family setup which is becoming the main reason for the loss of days when family members used to be responsible for elderly care. The ageing population in Pakistan are suffering from severe health and care issues. The Pakistani society, which once used to consider the senior citizen as a blessing now started considering them as a forced liability. Design/methodology/approach This study adopts the qualitative research strategy and interviews conducted in the local language with five women and men elderly each residing in old folk homes. Findings The study revealed that the main reasons behind increasing old folk trends in Pakistan are lack of family support, migration of children, less community awareness, economic issues, loneliness, dementia and invasion of western culture. Originality/value This study adopts the qualitative research strategy and interviews conducted in the local language with five women and men elderly each residing in old folk homes. The study revealed that the main reasons behind increasing old folk trends in Pakistan are lack of family support, migration of children, less community awareness, economic issues, loneliness, dementia and invasion of western culture.

Invasibility of Common Plant Community Types of the Middle Urals

This paper specifies the invasibility of common plant community types in the natural habitats of the Middle Urals. Invasibility was defined as the vulnerability of a community to alien plant species invasions, regardless of the conditions in which the community existed. We analyzed 749 vegetation relevés made in natural bogs, floodplains, rocky grasslands, meadows, and forest communities. We surveyed urban and non-urban habitats (30–40 km from the city). Invasibility was calculated in two different ways based on two parameters: the number and proportion of alien species in the relevé. These invasibility parameters are widely applicable and comparable, scale-independent, measurable, and reliable, based on data that do not require the destruction of ecosystems or biota and are based on available data. Based on the invasibility degree, we identified three community-type groups with two subgroups in one group. In ascending order of invasibility degree, the community types were arranged as follows: (1) bogs with and without trees; (2a) coniferous forests; grass communities in floodplains; (2b) deciduous forests, coniferous plantations, floodplain communities with woody plants; and (3) dry meadows and rocky grasslands. Obtained results of the assessment of different plant community invasibility may be used to understand patterns of alien plant distribution in local habitats and the reasons for the different vulnerability of communities to plant invasions.

Arbuscular mycorrhizal fungi inoculation exerts weak effects on species- and community-level growth traits for invading or native plants under nitrogen deposition

Nitrogen deposition and biological invasion are two major components of global environmental change. Nitrogen deposition has been considered to enhance the resource availability of recipient habitats, which influences the invasiveness of plant invader and the invasibility of recipient native communities. Nitrogen deposition has been shown to reduce the relative abundances of arbuscular mycorrhizal fungi (AMF) globally. AMF have been found to mutualistically symbiose with approximately 75% of plant species and act as a nutrient supplier. AMF may modify the structure of native plant communities, collaborate with alien plant invaders and thus promote their invasion. The alien woody invader, Rhus typhina L. has been introduced into North China as a horticultural species, invaded the native plant community and outperformed the native competitors in growth and in photosynthetic efficiency. Nevertheless, little is known about if nitrogen deposition and AMF inoculation synergistically alter the invasibility of native plant community. In this study, R. typhina was subjected to the artificial plant community assembled by four co-existing native species – Chenopodium album L., Vitex negundo var. heterophylla (Franch.) Rehd., Rhus chinensis Mill. and Acer truncatum Bunge in a mesocosm experiment. Nitrogen deposition and AMF inoculation were simulated as environmental and biotic filters respectively. Aboveground biomass and biomass proportion, reflecting plant growth and performance, and specific leaf area and chlorophyll concentration correlated with carbon use and photosynthetic capacity of both the alien invader and the native plants were measured and calculated after harvest. We found that AMF inoculation did not alter the trait variation of alien and native species to increasing nitrogen deposition level in general, although AMF inoculation impeded the increase of aboveground biomass for C. album, V. negundo and native community with increasing nitrogen deposition level. In the scenario of nitrogen deposition and AMF inoculation, a stable status of invasion dynamic may be maintained and needs to be checked with integration of traits at extended temporal scale.

An Internet of Things (IoT) Based Neighbourhood Distress Alert System

To acquiesce to the increase in territorial invasion of communities by hoodlums, bandits and kidnappers every day, some communities have resorted to engage the services of security agents or guards to watch over and alert them in the case of any security breach. However, the neighbourhood s found in some locations especially, in the rural areas impact on the cost of employing guards, and the consequent disagreement amongst residents in the neighbourhood security meeting. This paper proposes an Internet of Things (IoT) based system for alerting residents in a neighbourhood as well as reporting the actual location of a particular neighbour in distress. To achieve this, a hardware system based on NodeMCU with built-in Wi-Fi chip for internet routing is designed. Communication is established remotely between the hardware system and the cloud through the server Application Programming Interface (API) that utilizes cloud resources such as Short Message Service (SMS) gateway and Google map API to craft SMS and fetch location coordinate from Google map Uniform Resource Location (URL) respectively. This piece of information is then displayed on the Liquid Crystal Display (LCD) device on users’ machine and mobile phones in real time for notification. The test carried out shows that the developed system is reliable and affordable for use in a neighbourhood.

Distribution of N and recently fixed C among a common mycorrhizal network linking an invasive plant, Solidago canadensis, and a native plant, Kummerowia striata

Abstract The invasive plant species, Solidago canadensis, often shares a common mycorrhizal network (CMN) with native plant species in southeast China. We ask whether the transfer of carbon (C) and nitrogen (N) among the invasive S. canadensis, the native Kummerowia striata and their CMN could contribute to the invasiveness of S. canadensis. We conducted a microcosm experiment in which a CMN was established on S. canadensis and K. striata. We used 13CO2 pulse‐labelling to quantify the relative contribution of recently fixed C from the two host species to the CMN. We also calculated the relative N distribution to each host species from the CMN. We found that 89% of the recently fixed C in the CMN originated from S. canadensis, while 11% originated from K. striata. We also found that the CMN distributed 77% of the N it absorbed to S. canadensis and 23% to K. striata. Our results suggest that the unequal distribution of N from a CMN to the invasive and native plant species is related to the unequal contribution of C from the plant species. This mechanism could contribute to invasion of native communities by alien species when there is a stoichiometric exchange of limiting nutrients for C, and when alien species contribute more C to the CMN than natives. Read the free Plain Language Summary for this article on the Journal blog.

Spartina alterniflora invasion differentially alters microbial residues and their contribution to soil organic C in coastal marsh and mangrove wetlands

Coastal wetlands play a critical role in global carbon (C) cycling while they are frequently challenged by exotic plant invasion. Microbial residues are increasingly recognized as the key constituent of stable soil organic C (SOC) but their responses to plant invasion in coastal wetlands remain largely unknown. Here, we investigated the effect of Spartina alterniflora invasion on microbial residues and their contribution to SOC in coastal wetland ecosystems with distinct native species (Phragmites australis (marsh), Kandelia candel or Avicennia marina). S. alterniflora invasion differentially altered microbial residue C accumulation in three coastal wetlands. Overall, the invasion of S. alterniflora significantly increased microbial residue C accumulation (17.8%) in marsh with native P. australis, while it showed negative or minor impacts on mangroves with K. candel and A. marine communities, despite nuanced site-specific differences. The divergent responses of microbial residues could be related to changes in edaphic conditions and plant inputs along with plant invasion process. Invasion of mangrove and marsh communities by S. alterniflora triggered divergent fungal and bacterial residue responses, leading to contrasting fungal to bacterial C ratios in invaded marsh and mangrove wetlands. The proportion of microbial residues in SOC pool was enhanced to some extent, with an increase by 14.4%, 33.0% and 1.9% in P. australis, K. candel and A. marine wetlands, respectively, despite inconsistent variations in total SOC with S. alterniflora invasion. This has an implication for an elevated preservation of microbial residue C relative to the other organic C fractions in the invaded coastal wetlands. These findings highlight the importance of anabolic microbial C sequestration process for the maintenance of wetland soil C, which may impact C cycling and balance in coastal wetland ecosystem subjected to S. alterniflora invasion. Our work provides new insights to capture the properties and mechanisms of microbial control over C sequestration as well as SOC source configuration in coastal wetlands undergoing S. alterniflora invasion.

Species invasiveness and community invasibility of North American freshwater fish fauna revealed via trait-based analysis

While biological invasions are recognized as a major threat to global biodiversity, determining non-native species’ abilities to establish in new areas (species invasiveness) and the vulnerability of those areas to invasions (community invasibility) is challenging. Here, we use trait-based analysis to profile invasive species and quantify the community invasibility for >1,800 North American freshwater fish communities. We show that, in addition to effects attributed to propagule pressure caused by human intervention, species with higher fecundity, longer lifespan and larger size tend to be more invasive. Community invasibility peaks when the functional distance among native species was high, leaving unoccupied functional space for the establishment of potential invaders. Our findings illustrate how the functional traits of non-native species determining their invasiveness, and the functional characteristics of the invaded community determining its invasibility, may be identified. Considering those two determinants together will enable better predictions of invasions.