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Although most studies of factors contributing to successful establishment and spread of non-native species have focused on species traits and characteristics (both biotic and abiotic), increasing empirical and statistical evidence implicates propagule pressure—propagule sizes, propagule numbers, and temporal and spatial patterns of propagule arrival—as important in both facets of invasion. Increasing propagule size enhances establishment probability primarily by lessening effects of demographic stochasticity, whereas propagule number acts primarily by diminishing impacts of environmental stochasticity. A continuing rain of propagules, particularly from a variety of sources, may erase or vitiate the expected genetic bottleneck for invasions initiated by few individuals (as most are), thereby enhancing likelihood of survival. For a few species, recent molecular evidence suggests ongoing propagule pressure aids an invasion to spread by introducing genetic variation adaptive for new areas and habitats. This phenomenon may also explain some time lags between establishment of a non-native species and its spread to become an invasive pest.

AimIn 2024, cargo vessels must meet the International Maritime Organization's global ballast water discharge standards (IMO D-2) that limit the concentration of living organisms. D-2 focuses on reducing invasion risk by reducing ‘community propagule pressure (CPP)’, though it does not consider colonization pressure (CP).LocationGlobal.MethodsWe modelled risk differences in IMO D-2-compliant discharges (10 ind. m−3) for communities that had inverse patterns of CP and species' individual propagule pressures (IPP). Secondly, we determined the effect on risk of varying CPP and CP. As part of this, we tested whether the IMO D-2 standard for zooplankton-sized organisms of <10 individuals m−3 was an optimal choice. Risk was defined as probability of at least one species invading using four risk–release models.ResultsRisk differed strongly at the D-2 limit based on community composition. At low CPP (<25 ind. m−3), risk was strongly affected by CP for hyperbolic and linear risk–release models and weakly for exponential and logistic models, while CPP affected only the former two model types. Across a much wider range of CPP values, risk was affected by CP, CPP and by their interaction for all models.Main ConclusionThe IMO D-2 standard for zooplankton-sized organisms requires very low CPP and even lower IPPs in mixed-species releases, which will impede successful colonization. Species-abundance theory predicts that discharges meeting the D-2 standard (low CPP) will also have low CP. Much more empirical data are required to determine whether vessels can consistently reduce CP as it lowers CPP in order to meet these requirements.

Pinellia ternata , a common medicinal plant in East Asia, holds significant economic and therapeutic values. However, the market industrialization of the P. ternata is retarded due to the lack of a further understanding of its cultivation patterns. Here, we report an efficient cultivation model for P. ternata . This study featured a design with four planting depths (5 cm, 10 cm, 15 cm, and 20 cm) and five types of propagation materials, forming 20 distinct experimental groups. Each group was replicated three times. This study thoroughly analyzed the specific impacts of two types and five different sizes of propagules, as well as four different planting depths, on the propagation coefficient, agronomic traits, yield, and quality of P. ternata . (1) Tubers outperformed bulbils in propagation coefficient, agronomic traits, yield, and quality, with larger propagules showing better performance than smaller ones. (2) Small-diameter propagules (≤ 1.6 cm) achieved the best propagation coefficient, yield, and quality at a planting depth of 5 cm. (3) Large-diameter propagules (1.6–2.0 cm) showed maximum yield and quality component accumulation at 10 cm. (4) Correlation analysis indicated propagation coefficient, yield, and quality were negatively correlated with planting depth but positively correlated with propagule size. In conclusion, this study provides important theoretical support for the cultivation model of P. ternata and is helpful to guide its industrial production.

Weeds can cause losses in soybean crops of up to 80%. Weed propagules influence weed population and diversity in the soil. This research aims to obtain the diversity and population of weed propagules in soybean fields with various soil depths. This research was conducted using surveys and interviews in soybean fields in Dlingo District, Bantul Regency, Special Region of Yogyakarta. The survey method was carried out by taking samples of weeds and soil in three plots of soybean land with a depth of 0 cm, 10 cm, 20 cm, and 30 cm using quadrats in three observation plots measuring 30 cm × 30 cm as well as an interview method to find out how soybean cultivation is carried out. Weed samples and soil samples were collected three weeks after planting (vegetative phase), six weeks after planting (flowering), nine weeks after planting (pod formation), and 11 weeks after planting (ripe pods), so there were 36 sample points in one shot in one phase. The results showed that weed propagules in soybean fields at a 0-10 cm soil depth had higher diversity than at a 20-30 cm soil depth. The weeds that dominate soybean plantations are Portulaca oleracea, Euphorbia prostrata, Oldenlandia corymbosa , and Cleome rutidosperma . Soil depth influences the population of weed propagules in soybean plantations. A soil depth of 0 cm has the highest population of weed propagules, and the population decreases in deeper soil. The results of this research can be used as a reference in determining appropriate methods of controlling weed propagules in soybean fields. The results of this research can be used as a reference in deciding appropriate weed control methods for weed conditions in soybean fields

Trichoderma spp. are a genus of well-known fungi that promote healthy growth and modulate different functions in plants, as well as protect against various plant pathogens. The application of Trichoderma and its propagules as a biological control method can therefore help to reduce the use of chemical pesticides and fertilizers in agriculture. This review critically discusses and analyzes groundbreaking innovations over the past few decades of biotechnological approaches to prepare active formulations containing Trichoderma. The use of various carrier substances is covered, emphasizing their effects on enhancing the shelf life, viability, and efficacy of the final product formulation. Furthermore, the use of processing techniques such as freeze drying, fluidized bed drying, and spray drying are highlighted, enabling the development of stable, light-weight formulations. Finally, promising microencapsulation techniques for maximizing the performance of Trichoderma spp. during application processes are discussed, leading to the next-generation of multi-functional biological control formulations.Key points• The development of carrier substances to encapsulate Trichoderma propagules is highlighted.• Advances in biotechnological processes to prepare Trichoderma-containing formulations are critically discussed.• Current challenges and future outlook of Trichoderma-based formulations in the context of biological control are presented.

Increasing studies have shown the importance of intraspecific trait variation (ITV) on ecological processes. However, the patterns and sources of ITV are still unclear, especially in the propagules of coastal vegetation. Here, we measured six hypocotyl traits for 66 genealogies of Kandelia obovata from 26 sites and analyzed how ITV in these traits was distributed across geography and genealogy through variance partitioning. We further constructed mixed models and structural equation models to disentangle the effects of climatic, oceanic, and maternal factors on ITV. Results showed that size‐related traits decreased along increasing latitudinal gradients, which was mainly driven by positive regulation of temperature on these traits. By contrast, ITV of shape trait was unstructured along latitudinal gradients and did not show any dependence among environmental variables. These findings indicate that propagule size mainly varied between populations, whereas propagule shape mainly varied between individuals. Our study may provide useful insights into the ITV in propagule from different functional dimensions and on a broad scale, which may facilitate mangrove protection in light of ITV. Size‐related traits decreased along increasing latitudinal gradients, which was mainly driven by positive regulation of temperature on these traits. By contrast, intraspecific variation in shape trait was unstructured along latitudinal gradients and did not show any dependence of environmental variables. These findings indicate that propagule size mainly varied between populations, whereas propagule shape mainly varied between individuals.

Invasion success is regulated by multiple factors. While the roles of disturbance and propagule pressure in regulating the establishment of non-native species are widely acknowledged, that of propagule morphology (a proxy for quality) is poorly known. By means of a multi-factorial field experiment, we tested how the number (5 vs. 10) and quality (intact, without fronds or without rhizoids) of fragments of the clonal invasive seaweed, Caulerpa cylindracea, influenced its ability to establish in patches of the native seagrass, Posidonia oceanica, exposed to different intensities of disturbance (0, 50, or 100% reduction in canopy cover). We hypothesized that the ability of fragments to establish would be greater for intact fragments (high quality) and reduced more by frond removal (low quality) than rhizoid removal (intermediate quality). At low propagule pressure or quality, fragment establishment was predicted to increase with increasing disturbance, whereas, at high propagule pressure or quality, it was predicted to be high regardless of disturbance intensity. Disturbance intensity, fragment number and quality had independent effects on C. cylindracea establishment success. Disturbance always facilitated fragment establishment. However, fragments retaining fronds, either intact or deprived of rhizoids, had higher establishment success than fragments deprived of fronds. Increasing propagule number had weak effects on the cover of C. cylindracea. Our results demonstrate that propagule traits enabling the acquisition of resources made available by disturbance can be more important than propagule number in determining the establishment and spread of clonal non-native plants. More generally, our study suggests that propagule quality is a key, yet underexplored, determinant of invasion success.

Substantial progress has been made in understanding how pathways underlie and mediate biological invasions. However, key features of their role in invasions remain poorly understood, available knowledge is widely scattered, and major frontiers in research and management are insufficiently characterized. We review the state of the art, highlight recent advances, identify pitfalls and constraints, and discuss major challenges in four broad fields of pathway research and management: pathway classification, application of pathway information, management response, and management impact. We present approaches to describe and quantify pathway attributes (e.g., spatiotemporal changes, proxies of introduction effort, environmental and socioeconomic contexts) and how they interact with species traits and regional characteristics. We also provide recommendations for a research agenda with particular focus on emerging (or neglected) research questions and present new analytical tools in the context of pathway research and management.

Ecologists have long acknowledged the importance of seed banks; yet, despite the fact that many plants rely on mycorrhizal fungi for survival and growth, the structure of ectomycorrhizal (ECM) fungal spore banks remains poorly understood. The primary goal of this study was to assess the geographic structure in pine‐associated ECM fungal spore banks across the North American continent. Soils were collected from 19 plots in forests across North America. Fresh soils were pyrosequenced for fungal internal transcribed spacer (ITS) amplicons. Adjacent soil cores were dried and bioassayed with pine seedlings, and colonized roots were pyrosequenced to detect resistant propagules of ECM fungi. The results showed that ECM spore banks correlated strongly with biogeographic location, but not with the identity of congeneric plant hosts. Minimal community overlap was found between resident ECM fungi vs those in spore banks, and spore bank assemblages were relatively simple and dominated by Rhizopogon, Wilcoxina, Cenococcum, Thelephora, Tuber, Laccaria and Suillus. Similar to plant seed banks, ECM fungal spore banks are, in general, depauperate, and represent a small and rare subset of the mature forest soil fungal community. Yet, they may be extremely important in fungal colonization after large‐scale disturbances such as clear cuts and forest fires.