Dispersal Distance Research Articles

The dispersal potential of endangered plants versus non‐native garden escapees

Abstract Amidst climate change, enhancing plant dispersal pathways is crucial for adapting ecosystems and preserving biodiversity. In our human‐dominated landscapes, urban and rural green spaces, especially gardens, are promising conduits for plant dispersal. Non‐native plants are known to benefit from these spaces, yet the potential benefits for at‐risk native plants remain unclear. Here, I synthesized data on dispersal traits, comparing endangered native plants with non‐endangered and non‐native species in Germany. To make my analysis pertinent to understanding the potential role of gardens in aiding the dispersal of at‐risk native plants, I further contrasted the dispersal ecology of garden‐friendly endangered plants with non‐native plants known to escape gardens. I analysed several traits including seed weight, terminal velocity, dispersal distance, germination rate, dispersal mode, seed structures and seedbank type. Overall, dispersal traits between native and non‐native plants showed minor, but in some cases statistically significant differences. Endangered plants were more often wind‐dispersed and more frequently had seed appendages conducive to a wider range of dispersal vectors. Conversely, non‐native plants leaned more towards non‐assisted local dispersal, heavier seeds and more persistent seed banks. Other traits were largely consistent across groups. This research shows that endangered native plants possess a dispersal ecology similar to non‐native species, which frequently spread from green spaces like gardens. Thus, integrating endangered flora into our green spaces could help to promote an essential aspect of species survival: dispersal.

CFD Simulation and ANN Prediction of Hydrogen Leakage and Diffusion Behavior in a Hydrogen Refuelling Station

Hydrogen refueling station (HRS) is an essential part of the infrastructure for promoting the hydrogen economy. Since hydrogen is a flammable and explosive gas, hydrogen released from high‐pressure hydrogen storage equipment in HRS will likely cause combustion or explosion accidents. Studying high‐pressure hydrogen leakage in HRS is a prerequisite for promoting hydrogen fuel cell vehicles and HRS. A computational fluid dynamics (CFD) model of an HRS in a demonstrated project in Ningbo, China, was established on the ANSYS FLUENT software platform. The CFD model for hydrogen leakage simulation was validated by comparing the simulation results with experimental data in the literature. The effects of the direction and mass flow rate of the hydrogen leakage jet, as well as the direction and speed of ambient wind, on hydrogen diffusion behavior were investigated. The spreading distances of the flammable hydrogen cloud were predicted using an artificial neural network for horizontal leakage. The results show that the jet direction strongly affected the flammable cloud flow. The greater the mass flow rate of the leak, the greater the hydrogen dispersion distance and the volume of the flammable hydrogen cloud. At a hydrogen leakage mass flow rate of 4.5589 kg/s, the volume of the hydrogen flammable cloud reached 6,140.46 m3 at 30 s of leakage. The ambient wind speed has complicated effects on spreading the flammable cloud. The wind makes the flammable cloud move in certain directions, and the higher wind speed accelerates the diffusion of the flammable gas in the air. The results of the study can be used as a reference for the study of high‐pressure hydrogen leakage in HRS and will play an important role in the safe demonstration of the studied project.

Fruiting phenology in Aspidosperma discolor and implications for seed dispersal and population distribution

Abstract We investigated Aspidosperma discolor fruiting in three subpopulations in the inland Atlantic Forest of Northeastern Brazil, to better understand how local and global factors (such as the El Niño Southern Oscillation - ENSO) drive fruiting, and how functional traits are related to its dispersal potential and spatial distribution. Observations of mature fruits with dispersing seeds were carried out between 1993 and 2012. Dispersal potential was evaluated using seeds released at two different heights. Spatial distribution was analyzed using the Standardized Morisita dispersal index. A. discolor displayed seasonal fruiting during the dry season in all subpopulations, with variations in their average dates but without significant interannual variations in the proportions of fruiting individuals. The undulate seeds had average dispersal distances between 57.36 and 79.54 m. We found a random distribution pattern of the trees. The seasonal dry/rainy regime influenced fruiting and dispersal patterns, and seeds were released during the dry season (even in ENSO years). So, we demonstrate the importance of wind dispersal as a driving factor of fruiting, associated with an abiotic filter (low humidity) during the dry season. Additionally, the aerodynamic nature of the undulate diaspore and its dispersal potential influenced the random pattern of spatial distribution of A. discolor.

Side effects of X-ray irradiation on flight ability of Cydia pomonella moth.

The sterile insect technique (SIT) has proven to be an effective approach in managing the population of major invasive pests. Our previous studies showed that irradiation of Cydia pomonella males at a dosage of 366 Gy X-rays resulted in complete sterility. However, the mating competitiveness of sterilized males is significantly compromised, which can be attributed to a decline in their ability to fly. In this study, we examined the flight patterns of both male and female adults of C. pomonella. The results revealed significant variations in the average flight speed of both genders at different stages of maturity, with females displaying longer flight duration and covering greater distances. Effect of irradiation on the flight performance of 3-day-old male moths was further evaluated, as they demonstrated the longest flight distance. The findings indicated a significant decrease in flight distance, duration, and average speed, due to wing deformities caused by irradiation, which also limited the dispersal distance of moths in orchards, as indicated by the mark-and-recapture assay. Reverse-transcription quantitative polymerase chain reaction analysis revealed a down-regulation of flight-related genes such as Flightin, myosin heavy chain, and Distal-less following radiation exposure. These findings demonstrate that X-ray irradiation at a radiation dose of 366 Gy has a detrimental effect on the flight ability of male C. pomonella adults. These insights not only contribute to a better understanding of how radiation sterilization diminishes the mating competitiveness of male moths, but also aid in the development and improvement of SIT practices for the effective control of C. pomonella. © 2023 Society of Chemical Industry.

Enhancement Methods of Hydropower Unit Monitoring Data Quality Based on the Hierarchical Density-Based Spatial Clustering of Applications with a Noise-Wasserstein Slim Generative Adversarial Imputation Network with a Gradient Penalty.

In order to solve low-quality problems such as data anomalies and missing data in the condition monitoring data of hydropower units, this paper proposes a monitoring data quality enhancement method based on HDBSCAN-WSGAIN-GP, which improves the quality and usability of the condition monitoring data of hydropower units by combining the advantages of density clustering and a generative adversarial network. First, the monitoring data are grouped according to the density level by the HDBSCAN clustering method in combination with the working conditions, and the anomalies in this dataset are detected, recognized adaptively and cleaned. Further combining the superiority of the WSGAIN-GP model in data filling, the missing values in the cleaned data are automatically generated by the unsupervised learning of the features and the distribution of real monitoring data. The validation analysis is carried out by the online monitoring dataset of the actual operating units, and the comparison experiments show that the clustering contour coefficient (SCI) of the HDBSCAN-based anomaly detection model reaches 0.4935, which is higher than that of the other comparative models, indicating that the proposed model has superiority in distinguishing between the valid samples and anomalous samples. The probability density distribution of the data filling model based on WSGAIN-GP is similar to that of the measured data, and the KL dispersion, JS dispersion and Hellinger's distance of the distribution between the filled data and the original data are close to 0. Compared with the filling methods such as SGAIN, GAIN, KNN, etc., the effect of data filling with different missing rates is verified, and the RMSE error of data filling with WSGAIN-GP is lower than that of other comparative models. The WSGAIN-GP method has the lowest RMSE error under different missing rates, which proves that the proposed filling model has good accuracy and generalization, and the research results in this paper provide a high-quality data basis for the subsequent trend prediction and state warning.

Pilot study on the use of soft release for translocation of rehabilitated eastern box turtles (Terrapene carolina carolina)

Successfully rehabilitated eastern box turtles (EBTs, Terrapene carolina carolina) originating from destroyed or degraded habitats are prime candidates for translocation. However, physiological and behavioral characteristics of chelonians often lead to acclimation difficulties and limited survival post-release. Soft release is a translocation technique whereby an animal is held in a pen on location and allowed to acclimate to its new habitat area for a predetermined duration prior to release. This pilot study explored the viability of small-scale, soft release penning to aid wildlife rehabilitators in the translocation of rehabilitated EBTs. We hypothesized that soft release penning is a practical strategy to help rehabilitated EBTs maintain health and appropriately sized territory in new environments. We built and deployed two soft release pens that were used to relocate three rehabilitated EBTs with varying success to an urban greenspace in Nashville, Tennessee. Our results suggest that soft release penning provides a unique opportunity to observe health and behavior in a controlled environment during the initial period of acclimation, and this early intervention period may help rehabilitators facilitate successful translocation. Further research is recommended to evaluate the direct impacts of soft release pens on body condition, dispersal distance, and home range size of translocated EBTs.

Landscape structure does not hinder the dispersal of an invasive herbivorous mammal in the New Caledonian biodiversity hotspot

Biological invasions are a major threat to biodiversity and have particularly devastating impacts on island ecosystems. The New Caledonia archipelago is considered a biodiversity hotspot due to its diverse native flora. Javan rusa deer (Rusa timorensis) were introduced to New Caledonia in 1870 and the population consists of several hundred thousand individuals today. They directly threaten rare endemic species and affect the composition and structure of the vegetation. While a rusa deer management plan has identified ten priority areas for deer control operations, removing deer could be offset by the dispersal of animals back into the control areas. Here, we genotyped 628 rusa deer using 16 microsatellite markers to analyse the genetic structure of the animals in New Caledonia. We aimed to assess fine-scale genetic structure, to identify natural barriers to deer movement and to assess functional connectivity by optimising individual-based landscape resistance models. Our results suggested that rusa deer formed a single genetic population on the main New Caledonian island. The isolation-by-distance pattern suggested that female dispersal was limited, whereas males had larger dispersal distances. We assessed functional connectivity using different genetic distance metrics and all models performed poorly (mR2 ≤ 0.0043). Landscape features thus hardly affected deer movement. The characteristics of our results suggested that they were not an artefact of the colonisation history of the species. Achieving an effective reduction of deer population sizes in specific management areas will be difficult because of the deer’s high dispersal capabilities and impossible without very substantial financial investment.

Influence of climate and landscape on genetic differentiation of aardvarks (Orycteropus afer)

AbstractAimAs climate change accelerates, assessing how climate shapes gene flow and neutral and adaptive genetic differentiation on landscapes is increasingly important. Aardvarks (Orycteropus afer) are ecologically important in sub‐Saharan Africa but are sensitive to human pressures and increasing aridity. We used individual, population and landscape genetic approaches to infer the influence of landscape, climate and potential adaptive differences on gene flow.LocationWe surveyed 8 protected and 4 privately owned areas in South Africa, 2 protected areas in Eswatini and one location in Kenya during 2016–2018.MethodsWe developed microsatellite markers and methods for DNA extraction from faeces, collected and genotyped faecal samples from focal areas and estimated genetic structure. We inferred space use from individual redetections, tested for close relatives and estimated genetic neighbourhood distance. We applied individual‐based landscape genetic analyses at multiple scales to test hypotheses about genetic differentiation by landscape resistance and potential adaptive differences.ResultsWe developed 19 variable microsatellite loci and collected 253 faecal samples from 13 focal areas. We genotyped 104 samples successfully at ≥8 loci as needed for individual identification. The genetic structure suggested 3 regional divisions in South Africa. We detected individuals at locations ≤7.3 km distant and closely related individuals at ≤44 km; genetic neighbourhood distance was <55 km. Lower precipitation increased landscape resistance and strongly predicted genetic differentiation at most spatial scales. Temperature differences at sampling sites also influenced structure, suggesting climate‐associated adaptive differences.Main ConclusionsThe genetic structure of aardvarks is strongly shaped by climate, with arid areas limiting gene flow and reflects apparent isolation by adaptation associated with temperature. Dispersal distances likely are <55 km. The markers we developed will facilitate studies of space use, dispersal, population density or survival. Aridification will increase fragmentation and we recommend monitoring aardvark presence as an indicator of ecosystem change associated with aridification.

Habitat specialisation and resource availability determine dispersal behaviour in four afro‐tropical butterflies

Abstract Ecological demands, such as sex and environmental conditions, determine species' behaviour, such as dispersal, and shape local population structures. However, only marginal knowledge of these factors exists for afro‐tropical insects so far. Therefore, we performed a mark–release–recapture study in the coastal region of Kenya over a period of 2 months, covering the dry and the rainy seasons. As study species, we used four co‐occurring but ecologically diverging butterfly species, the forest species Bicyclus safitza and Junonia natalica and the savannah species Junonia oenone and Byblia ilithyia. The study area represents an ecosystem mosaic consisting of anthropogenic habitats as well as natural forest and savannah, assessed by detailed landscape mapping. We obtained 1701 capture events, comprising 1224 individuals with an overall recapture rate of 24% (ranging from 15% to 48%). The analyses based on these results allowed an assessment of the population ecology, dispersal behaviour and habitat preferences of these species. Demographic models inferred different patterns of population dynamics among species. All species preferred the habitats they were known for. The observed dispersal distances were rather low ranging from a mean of 25 to 72 m, referring to taxa and sexes. The dispersal extrapolations were unreliably low for the negative exponential function, while the values for inverse power function were credible. The latter predicted a considerably higher long‐distance dispersal capacity in males than in females of the forest species B. safitza and J. natalica, while females dispersed more than males in the savannah species J. oenone and B. ilithyia. Our results obtained from these four ecologically diverging afro‐tropical butterfly species underline that species’ behaviour, such as dispersal, is strongly determined by habitat preferences, sex and the availability of resources.

Evaluation of the Potential Seed Dispersal Effectiveness of Malus sieversii (Lebed.) M. Roem. by Cattle

The success of plant reproduction is highly dependent on effective seed dispersal. This study aimed to evaluate the potential seed dispersal effectiveness of cattle for Malus sieversii. The impact of cattle on the dispersal quantity and dispersal quality of M. sieversii seeds was explored based on camera trapping, GPS tracking, and germination trials. The results showed that, on average, cattle visited M. sieversii trees 477.33 times during a two-month observation period. Out of these visits, 315 were specifically for fruit removal. The fruit removal rate per cattle visit was as high as 96.67%. Additionally, cattle were able to disperse M. sieversii seeds up to a maximum distance of 533.67 m, with an average dispersal distance of 134.62 m. The average distance of cattle movement was recorded as 176.95 m/h, with peak activity observed during 11:00–13:00 and 19:00–21:00. The germination rate of M. sieversii seeds that passed through the digestive tract of cattle was significantly higher than that of control seeds. Finally, the emergence rate and survival rate of seeds dispersed by cattle to forest edges and gaps were significantly higher than those dispersed to understory. These findings suggest that cattle can serve as effective long-distance dispersers of M. sieversii seeds and may play a crucial role in the regeneration and expansion of M. sieversii populations in the Ili Botanical Garden.

Movement Ecology of Adult Western Corn Rootworm: Implications for Management.

Movement of adult western corn rootworm, Diabrotica virgifera virgifera LeConte, is of fundamental importance to this species' population dynamics, ecology, evolution, and interactions with its environment, including cultivated cornfields. Realistic parameterization of dispersal components of models is needed to predict rates of range expansion, development, and spread of resistance to control measures and improve pest and resistance management strategies. However, a coherent understanding of western corn rootworm movement ecology has remained elusive because of conflicting evidence for both short- and long-distance lifetime dispersal, a type of dilemma observed in many species called Reid's paradox. Attempts to resolve this paradox using population genetic strategies to estimate rates of gene flow over space likewise imply greater dispersal distances than direct observations of short-range movement suggest, a dilemma called Slatkin's paradox. Based on the wide-array of available evidence, we present a conceptual model of adult western corn rootworm movement ecology under the premise it is a partially migratory species. We propose that rootworm populations consist of two behavioral phenotypes, resident and migrant. Both engage in local, appetitive flights, but only the migrant phenotype also makes non-appetitive migratory flights, resulting in observed patterns of bimodal dispersal distances and resolution of Reid's and Slatkin's paradoxes.

Elevated temperatures shift flower head height distributions and seed dispersal patterns in two invasive thistle species.

Climate change may significantly alter how organisms disperse, with implications for population spread and species management. Wind-dispersed plants have emerged as a useful study system for investigating how climate change affects dispersal, although studies modeling wind dispersal often assume propagules are released from a single point on an individual. This simplifying assumption, while useful, may misestimate dispersal. Here, we investigate the effects of climate change on dispersal distances and spread rates, examining how these quantities shift when accounting for all points of seed release on an individual. Using the wind-dispersed invasive thistles Carduus nutans and Carduus acanthoides, we quantify temperature-driven shifts in the distribution of flower head heights using a passive warming field experiment, and estimate how these shifts affect dispersal using the Wald analytical long-distance (WALD) model; for C. nutans, we use existing demographic data to simulate how these shifts affect population spread rates. We also compare dispersal distances for both warmed and ambient temperature plants, considering the entire distribution of flower head heights versus the common assumption of point-source seed release at the maximum height. For experimentally grown individuals, an ~0.6°C higher growing temperature increased mean and maximum flower head height by 14.1 cm (15.0%) and 14.0 cm (13.2%), respectively, in C. nutans and by 21.2 cm (26.6%) and 31.8 cm (36.7%), respectively, in C. acanthoides. Seeds from warmed individuals were more likely to exceed a given dispersal distance than those from their unwarmed counterparts; warmed C. nutans and C. acanthoides seeds were on average 1.36 and 1.71 times as likely, respectively, to travel 10 m or more in dispersal simulations, with this disparity increasing at longer dispersal distances. For C. nutans, increased growing temperatures boosted simulated rates of population spread by 42.2%, while assuming dispersal from a maximum height point source rather than the true distribution of flower head heights increased simulated spread by up to 28.5%. Our results not only demonstrate faster population spread under increased temperatures, but also have substantial implications for modeling such spread, as the common simplifying assumption of dispersal from a single maximum height source may substantially overestimate spread rates.

A spatial analysis of urban gulls contribution to the potential spread of zoonotic and antibiotic-resistant bacteria

Wildlife human interactions within cities are becoming more common with consequences for pathogen transmission and human health. Large gulls are opportunistic feeders, adapted to coexist with humans in urban environments, and are potential vectors for spread and transmission of pathogens, including antimicrobial-resistant bacteria. We investigated the potential role that urban gulls play in the spread and dispersal of these bacteria. We analysed 129 faecal swabs from yellow-legged gulls (Larus michahellis) of different ages (56 adults and 73 immatures) during the breeding period from three years in the highly populated city of Barcelona (northeastern Spain). Thirteen individuals tested positive for the pathogenic bacteria (Escherichia coli, Listeria monocytogenes, Campylobacter jejuni), including antibiotic-resistant strains. We modelled the potential spatial spread of pathogens using the GPS trajectories of 58 yellow-legged gulls (23 adults, 35 immature individuals), which included the thirteen individuals that tested positive for pathogenic bacteria. By overlapping the spatially explicit pathogen dispersal maps with the distribution of urban installations sensitive at risk of possible pathogen spillover (e.g. elder and medical centres, markets, food industries, kindergartens, or public water sources), we identified potential areas at risk of pathogen spillover. Pathogens may be potentially spread to municipalities beyond Barcelona city borders. The results revealed that immature gulls dispersed pathogens over larger areas than adults (maximum dispersal distances of 167 km versus 53.2 km, respectively). Recreational urban water sources were the most sensitive habitats visited by GPS-tagged gulls that tested positive, followed by schools. Combining GPS movement data with pathogen analytics allows spatially explicit maps to be generated using a One Health approach that can help urban and public health management within large cities, such as Barcelona, and identify areas used by humans that are sensitive to pathogen spillover from gulls.

Dispersal modes affect Rhamnaceae diversification rates in a differentiated manner.

The evolution of dispersal modes has been proposed to promote the diversification of angiosperms. However, little is known about the relative impact of different dispersal modes on plant diversification. We test the association between dispersal modes and diversification rates using Rhamnaceae, the cosmopolitan buckthorn family, as a model. We found that species with diplochory have the highest diversification rates followed by those with myrmecochory and ballistic dispersal, while lineages dispersed by vertebrates and wind have relatively low diversification rates. The difference in diversification rates may be closely linked to the difference in dispersal distance and ecological interactions implied by each dispersal mode. Species which disperse over larger geographical distances may have much higher speciation rates due to the increased chance of establishing isolated populations due to geological barriers or habitat fragmentation. However, long-distance dispersal may also increase the chance of extinction. By contrast, species with short-distance dispersal modes may have low speciation rates. Complex interactions with the surrounding environment may, however, impact diversification rates positively by increasing plant survival and reproductive success.

Predicting the spatio-temporal distribution of the invasive alien plant Andropogon virginicus, in the South Korean peninsula considering long-distance dispersal capacities.

The spread of invasive alien species is a major threat to biodiversity. Estimating the long-distance dispersal capacity of invasive alien plants is vital for understanding their population dynamics and community composition. We predicted the spatial-temporal distribution of the alien plant Andropogon virginicus, in the Korean peninsula under climate change scenario using Random Forest (RF) and Cellular Automaton (CA) methods. Land use, barriers to dispersal, long-distance dispersal frequency, and maximum long-distance dispersal range were considered in our analysis. Our results showed that, among the five selected environmental variables, annual mean temperature and Human Foot-Printing (HFP) were positively associated with the occurrence probability of A. virginicus. This suggests that A. virginicus is likely to spread to the disturbed northern part of the Korean Peninsula due to climate change and habitat preference. When comparing modeling results for dispersal to field survey data, the modeling raster sets drawn from the long-distance dispersal frequency of 0.05 and maximum long-distance dispersal distance of 30 km y-1 had the most similar spatial expansion among the six long-distance dispersal parameter sets. The dispersal directions were associated with the landscape. Specifically, seeds dispersed by wind (anemochorous seeds) could propagate into open landscapes more easily than in forests. Regarding A. virginicus management, this grass can quickly invade bare ground with their wind-dispersed seeds, therefore habitat destruction, such as excessive logging and weeding, should be restrained.

Contrasted spatial, demographic and genetic structures of a light-demanding African timber species, Cylicodiscus gabunensis Harms – Implications for a sustainable management of its populations

Most Central African rainforest canopies consist of light-demanding tree species that hold high commercial value but also suffer locally from regeneration deficits, raising concerns about the sustainability of logging. Regeneration is influenced by factors such as past perturbations (including human activity), mating systems, and seed/pollen dispersal processes that impact demographic, spatial, and genetic structures within populations. To gain a better understanding of these interactions, we studied the spatial distribution and trunk diameter structure of Cylicodiscus gabunensis (Fabaceae) - a wind-dispersed, insect-pollinated, timber species - in three plots ranging from 400 to 839 ha situated in various environmental contexts (e.g. forest types and elephant densities) across Central Africa. We also genotyped adults and juveniles using microsatellite markers to analyze the spatial genetic structure of each population and infer the selfing rate, seed and pollen dispersal capacities and selection gradients using the ‘neighborhood model’. The selfing rate was low (3 – 4 %), and seed dispersal distances (ds = 184 m) were much shorter than pollen dispersal distances (dp > 2 km). The three populations displayed contrasted spatial, demographic and genetic structures. One population showed no spatial aggregation or genetic structure, and a multimodal diameter structure indicating pulses of regeneration events. Two populations showed strong spatial aggregation and genetic structures. One exhibited a unimodal diameter structure indicating one ancient pulse of regeneration, while the other displayed a 'reverse J-shaped' diameter structure, typical of ongoing regeneration. In the latter, reproductive success appeared leptokurtic, three mother trees accounting for over 90 % of the regeneration and no tree below the minimum cutting diameter implemented by logging companies had offspring. The idiosyncratic nature of population characteristics observed in C. gabunensis suggests that, for sustainable management, a nuanced approach is needed. This involves protecting productive seed trees in areas where natural regeneration is occurring and actively supporting regeneration in areas exhibiting deficits, especially in contexts with low elephant densities.

Sensitivity of habitat network models to changes in maximum dispersal distance

Predicting the presence or absence (occurrence-state) of species in a certain area is highly important for conservation. Occurrence-state can be assessed by network models that take suitable habitat patches as nodes, connected by potential dispersal of species. To determine connections, a connectivity threshold is set at the species’ maximum dispersal distance. However, this requires field observations prone to underestimation, so for most animal species there are no trustable maximum dispersal distance estimations. This limits the development of accurate network models to predict species occurrence-state. In this study, we performed a sensitivity analysis of the performance of network models to different settings of maximum dispersal distance. Our approach, applied on six amphibian species in Switzerland, used habitat suitability modelling to define habitat patches, which were linked within a dispersal distance threshold to form habitat networks. We used network topological measures, patch suitability, and patch size to explain species occurrence-state in habitat patches through boosted regression trees. These modelling steps were repeated on each species for different maximum dispersal distances, including a species-specific value from literature. We evaluated mainly the predictive performance and predictor importance among the network models. We found that predictive performance had a positive relation with the distance threshold, and that almost none of the species-specific values from literature yielded the best performance across tested thresholds. With increasing dispersal distance, the importance of the habitat-quality-related variable decreased, whereas that of the topology-related predictors increased. We conclude that the sensitivity of these models to the dispersal distance parameter stems from the very different topologies formed with different movement assumptions. Most reported maximum dispersal distances are underestimated, presumably due to leptokurtic dispersal distribution. Our results imply that caution should be taken when selecting a dispersal distance threshold, considering higher values than those derived from field reports, to account for long-distance dispersers.

Study on the anti-corrosion and barrier ability of modified sulfoaluminate cement mortar cutoff wall against sulfate

Calcined layered double hydroxide (CLDH) was used to modify sulfoaluminate cement (SAC) mortar to develop a new sulfate-resistant barrier material. Through investigations into mechanical properties, permeability, microstructure, and migration characteristics, the results demonstrated that the addition of CLDH improved the mechanical properties and pore structure of SAC mortar and inhibited the diffusion of SO42-. Based on its anti-corrosion and barrier ability, the optimal CLDH dosage in SAC mortar was determined to be 2 % of the cement mass. Service life calculations and Visual MODFLOW simulations demonstrated that the SAC-CLDH cutoff wall has significant durability and barrier effect on sulfate. Compared to the site without the SAC-CLDH cutoff wall, the effective dispersion distance and area of sulfate decreased by 88.79 % and 93.43 % during 4000 days. This finding provides a new reference for the containment and management of high-concentration sulfate-contaminated sites.

The comparison of dispersal rate between invasive and native species varied by plant life form and functional traits

A long dispersal distance is widely used to indicate high invasiveness, but it ignores the temporal dimensions of plant invasion. Faster dispersal rates (= distance/time) of invasive species than native ones have been widely used in modeling species invasion and planning control management. However, the comparison of dispersal rate between invasive and native plants, particularly for dispersal on a local or landscape scale, has not been tested with a comprehensive dataset. Moreover, both the effects of plant functional traits on the dispersal rate and variation in the functional-trait effects between invasive and native plants remain elusive. Compiling studies from 30 countries globally, we compared seed dispersal rates (km/year) on a local or landscape scale between 64 observations of invasive and 78 observations of native plants given effects of plant life forms, disturbance levels, and measurement methods. Furthermore, we compared the effects of functional traits on dispersal rate between invasive and native species. We found that: (1) Trait values were similar between the invasive and native plants except for the greater height of woody native plants than woody invasive ones; (2) Compared within the same plant life form, the faster dispersal rates of invasive species were found in herbaceous plants, not in woody plants, and disturbance level and measurement methods did not affect the rate comparison; (3) Plant height and seed length had significant effects on dispersal rates of both invasive and native plants, but the effect of leaf dry matter content (LDMC) was only significant on herbaceous invasive plants. The comparison of dispersal rate between invasive and native plants varied by plant life form. The convergent values but divergent dispersal effects of plant traits between invasive and native species suggest that the trait effects on invasiveness could be better understood by trait association with key factors in invasiveness, e.g., dispersal rate, than the direct trait comparison between invasive and native plants.

Extinction risk of the world's freshwater mammals.

The continued loss of freshwater habitats poses a significant threat to global biodiversity. We reviewed the extinction risk of 166 freshwater aquatic and semiaquatic mammals-a group rarely documented as a collective. We used the International Union for the Conservation of Nature Red List of Threatened Species categories as of December 2021 to determine extinction risk. Extinction risk was then compared among taxonomic groups, geographic areas, and biological traits. Thirty percent of all freshwater mammals were listed as threatened. Decreasing population trends were common (44.0%), including a greater rate of decline (3.6% in 20years) than for mammals or freshwater species as a whole. Aquatic freshwater mammals were at a greater risk of extinction than semiaquatic freshwater mammals (95% CI -7.20 to -1.11). Twenty-nine species were data deficient or not evaluated. Large species (95% CI 0.01 to 0.03) with large dispersal distances (95% CI 0.03 to 0.15) had a higher risk of extinction than small species with small dispersal distances. The number of threatening processes associated with a species compounded their risk of extinction (95% CI 0.28 to 0.77). Hunting, land clearing for logging and agriculture, pollution, residential development, and habitat modification or destruction from dams and water management posed the greatest threats to these species. The basic life-history traits of many species were poorly known, highlighting the need for more research. Conservation of freshwater mammals requires a host of management actions centered around increased protection of riparian areas and more conscientious water management to aid the recovery of threatened species.