A native species does not prevent the colonization success of an introduced submerged macrophyte, even at low propagule pressure

Urban systems often support large numbers of non-native species, but due to the heterogeneity of urban landscapes, species are not evenly distributed. Understanding the drivers of ecological resistance in urban landscapes may help to identify habitats that are most resistant to invasion, and inform efforts to model and conserve native biodiversity. We used pitfall traps to survey non-native ground-dwelling arthropods in three adjacent, low-elevation habitat types in southern California: California sage scrub, non-native grassland, and suburban development. We found that non-native species were fewer and less widely distributed in the sage scrub and grassland habitats. Due to the proximity of our sites, differences in propagule pressure is an unlikely explanation. Instead, we suggest that the absence of water subsidies in the sage scrub and grassland habitats increases those habitats’ resistance to arthropod invasions. Comparisons to studies conducted at fragments closer to the coast provide further support for the relationship between aridity and invasibility in southern California. Our findings highlight that inland fragments are important for conserving native arthropod diversity, that models of non-native species distributions in arid and semi-arid urban systems should include aridity measures, and that reducing resource subsidies across the region is critical to mitigating spread of non-natives.

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Community Structure Affects Annual Grass Weed Invasion During Restoration of a Shrub–Steppe Ecosystem

Invasive Plant Science and Management ◽

10.1614/ipsm-d-13-00021.1 ◽

2014 ◽

Vol 7 (1) ◽

pp. 1-13 ◽

Cited By ~ 8

Author(s):

Phil S. Allen ◽

Susan E. Meyer

Keyword(s):

Community Structure ◽

Native Species ◽

Propagule Pressure ◽

Alternative Hypothesis ◽

Perennial Grasses ◽

Invasion Success ◽

Sagebrush Steppe ◽

Annual Grass ◽

Shrub Steppe ◽

Steppe Communities

AbstractEcological restoration of shrub–steppe communities in the western United States is often hampered by invasion of exotic annual grasses during the process. An important question is how to create restored communities that can better resist reinvasion by these weeds. One hypothesis is that communities comprised of species that are functionally similar to the invader will best resist invasion, while an alternative hypothesis is that structurally more complex and diverse communities will result in more effective competitive exclusion. In this field experiment, we examined the effects of restored community structure on the invasion success of three annual grass weeds (downy brome, jointed goatgrass, and cereal rye). We created replicated community plots that varied in species composition, structural complexity and density, then seeded in annual grass weeds and measured their biomass and seed production the following year, and their cover after 1 and 3 yr. Annual grass weeds were not strongly suppressed by any of the restored communities, indicating that it was difficult for native species to completely capture available resources and exclude annual grass weeds in the first years after planting. Perennial grass monocultures, particularly of the early seral grass bottlebrush squirreltail, were the most highly invaded communities, while structurally complex and diverse mixtures of shrubs (big sagebrush, rubber rabbitbrush), perennial grasses (bluebunch wheatgrass and bottlebrush squirreltail) and forbs (Lewis flax, Utah sweetvetch, hairy golden aster, gooseberryleaf globemallow) were more resistant to invasion. These results suggest that restoration of sagebrush steppe communities resistant to annual grass invasion benefits from higher species diversity; significant reduction of weed propagule pressure prior to restoration may be required.

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PEIXES NÃO-NATIVOS EM RIACHOS NO BRASIL: ESTADO DA ARTE, LACUNAS DE CONHECIMENTO E PERSPECTIVAS

Oecologia Australis ◽

10.4257/oeco.2021.2502.21 ◽

2021 ◽

Vol 25 (02) ◽

pp. 565-587

Author(s):

Diego Azevedo Zoccal Garcia ◽

◽

Fernando Mayer Pelicice ◽

Marcelo Fulgêncio Guedes de Brito ◽

Mário Luís Orsi ◽

...

Keyword(s):

Native Species ◽

Propagule Pressure ◽

Human Impacts ◽

Biodiversity Loss ◽

Legal Aspects ◽

Native Fish ◽

Management Actions ◽

Brazilian Legislation ◽

The Subject ◽

Native Fishes

Biological invasions are among the main causes of biodiversity loss on planet. Losses are accentuated in streams, which are sensitive to human impacts, since they have specialized fauna and higher degree of endemism. Despite this, studies on invasions by non-native fish in streams are incipient in Brazil. In this review, we present an introduction on the process (i.e., stages) of biological invasion, the environmental factors that influence the establishment and the impacts of non-native species in streams. A methodological step-by-step is also presented as a way to guide the conduct of studies on non-native species in Brazilian streams. In addition, management actions measures are presented to prevent new cases of introductions and suggestions for studies on invasions in streams. Avoiding propagule pressure and environmental education, as well as legal aspects of Brazilian legislation, are management actions that can prevent new introductions. Finally, gaps in knowledge and perspectives are raised as an incentive for interested parties to enter the subject and develop new studies on non-native fishes in Brazilian streams.

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Long-term colonisation and propagule pressure of fish assemblages in a Neotropical floodplain

10.21203/rs.3.rs-268233/v1 ◽

2021 ◽

Author(s):

Luis Artur Valões Bezerra ◽

Simone Libralato ◽

Jan Kubecka ◽

Andre Padial

Keyword(s):

Biological Invasions ◽

Native Species ◽

Fish Assemblages ◽

Biotic Resistance ◽

Propagule Pressure ◽

Paraná River ◽

River Floodplain ◽

Parana River ◽

Paraná River Floodplain

Abstract Biological invasions are a major threat to biodiversity in the Neotropical region. However, few studies have evaluated the mechanisms underlying the long-term establishment of fish propagules in aquatic environments. Here, we associated fish biomass, species richness, and proportion of non-native species (contamination index) to quantify propagule and colonisation pressures, and fish biodiversity (measured by the Kempton’s index) in lakes and rivers of the Parana River floodplain. We organised species into native and non-native assemblages sampled by gillnetting and beach seining in spatio-temporal gradients, seasonally, from 2000 to 2017. Native and non-native Kempton’s indices were inversely correlated, native extinctions occurred locally with non-native biotic differentiation in lakes, rivers, and ecosystem contamination. A constant propagule pressure resulted in an overwhelming biodiversity of non-natives at the end of the evaluated time series. Biotic resistance to introduction was not evidenced in our deterministic trends. The observed patterns agreed with previous studies highlighting native biotic homogenisation and species extinctions, depending on biological invasions, landscape connectivity, and riverine impoundments. Long-term propagule pressure and non-native fish colonisation were the drivers of biodiversity that led to the predominance of non-native over native assemblages in the Parana River floodplain.

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The relative importance of latitude matching and propagule pressure in the colonization success of an invasive forb

Ecography ◽

10.1111/j.2006.0906-7590.04683_29_6.x ◽

2006 ◽

Vol 29 (6) ◽

pp. 819-826 ◽

Cited By ~ 19

Author(s):

John L. Maron

Keyword(s):

Propagule Pressure ◽

Relative Importance ◽

Colonization Success

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Kentucky Bluegrass Invasion in the Northern Great Plains and Prospective Management Approaches to Mitigate Its Spread

Plants ◽

10.3390/plants10040817 ◽

2021 ◽

Vol 10 (4) ◽

pp. 817

Author(s):

Rakhi Palit ◽

Greta Gramig ◽

Edward S. DeKeyser

Keyword(s):

Great Plains ◽

Native Species ◽

Management Practices ◽

Propagule Pressure ◽

Poa Pratensis ◽

Kentucky Bluegrass ◽

Northern Great Plains ◽

Ecological Interactions ◽

Management Tools ◽

Management Approaches

Kentucky bluegrass (Poa pratensis L.) is one of the most aggressive grasses invading Northern Great Plains (NGP) grasslands, resulting in substantial native species losses. Highly diverse grasslands dominated by native species are gradually transforming into rangelands largely dominated by non-native Kentucky bluegrass. Several factors potentially associated with Kentucky bluegrass invasions, including high propagule pressure, thatch formation, climate change, and increasing nitrogen deposition, could determine the future dominance and spread of Kentucky bluegrass in the NGP. Because atmospheric CO2 is amplifying rapidly, a C3 grass like Kentucky bluegrass might be photosynthetically more efficient than native C4 grasses. As this exotic species shares similar morphological and phenological traits with many native cool-season grasses, controlling it with traditional management practices such as prescribed fire, grazing, herbicides, or combinations of these practices may also impair the growth of native species. Thus, developing effective management practices to combat Kentucky bluegrass spread while facilitating the native species cover is essential. Modifying traditional techniques and embracing science-based adaptive management tools that focus on the ecological interactions of Kentucky bluegrass with the surrounding native species could achieve these desired management goals. Enhancement of the competitiveness of surrounding native species could also be an important consideration for controlling this invasive species.

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Trait positions for elevated invasiveness in adaptive ecological networks

Biological Invasions ◽

10.1007/s10530-021-02484-w ◽

2021 ◽

Author(s):

Cang Hui ◽

David M. Richardson ◽

Pietro Landi ◽

Henintsoa O. Minoarivelo ◽

Helen E. Roy ◽

...

Keyword(s):

Native Species ◽

Evolutionary Dynamics ◽

Propagule Pressure ◽

Adaptive Dynamics ◽

Evolutionary Game ◽

Ecological Networks ◽

Positive Interactions ◽

Ecological Network ◽

Invasion Fitness ◽

Ecological Barriers

AbstractOur ability to predict the outcome of invasion declines rapidly as non-native species progress through intertwined ecological barriers to establish and spread in recipient ecosystems. This is largely due to the lack of systemic knowledge on key processes at play as species establish self-sustaining populations within the invaded range. To address this knowledge gap, we present a mathematical model that captures the eco-evolutionary dynamics of native and non-native species interacting within an ecological network. The model is derived from continuous-trait evolutionary game theory (i.e., Adaptive Dynamics) and its associated concept of invasion fitness which depicts dynamic demographic performance that is both trait mediated and density dependent. Our approach allows us to explore how multiple resident and non-native species coevolve to reshape invasion performance, or more precisely invasiveness, over trait space. The model clarifies the role of specific traits in enabling non-native species to occupy realised opportunistic niches. It also elucidates the direction and speed of both ecological and evolutionary dynamics of residing species (natives or non-natives) in the recipient network under different levels of propagule pressure. The versatility of the model is demonstrated using four examples that correspond to the invasion of (i) a horizontal competitive community; (ii) a bipartite mutualistic network; (iii) a bipartite antagonistic network; and (iv) a multi-trophic food web. We identified a cohesive trait strategy that enables the success and establishment of non-native species to possess high invasiveness. Specifically, we find that a non-native species can achieve high levels of invasiveness by possessing traits that overlap with those of its facilitators (and mutualists), which enhances the benefits accrued from positive interactions, and by possessing traits outside the range of those of antagonists, which mitigates the costs accrued from negative interactions. This ‘central-to-reap, edge-to-elude’ trait strategy therefore describes the strategic trait positions of non-native species to invade an ecological network. This model provides a theoretical platform for exploring invasion strategies in complex adaptive ecological networks.

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Rethinking Biological Invasions as a Metacommunity Problem

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2020.584701 ◽

2021 ◽

Vol 8 ◽

Author(s):

Bryan L. Brown ◽

Jacob N. Barney

Keyword(s):

Biological Invasions ◽

Community Assembly ◽

Species Interactions ◽

Native Species ◽

Biotic Resistance ◽

Propagule Pressure ◽

Regional Scale ◽

Invasion Biology ◽

Enemy Release ◽

Multi Scale

Perhaps more than any other ecological discipline, invasion biology has married the practices of basic science and the application of that science. The conceptual frameworks of population regulation, metapopulations, supply-side ecology, and community assembly have all to some degree informed the regulation, management, and prevention of biological invasions. Invasion biology needs to continue to adopt emerging frameworks and paradigms to progress as both a basic and applied science. This need is urgent as the biological invasion problem continues to worsen. The development of metacommunity theory in the last two decades represents a paradigm-shifting approach to community ecology that emphasizes the multi-scale nature of community assembly and biodiversity regulation. Work on metacommunities has demonstrated that even relatively simple processes at local scales are often heavily influenced by regional-scale processes driven primarily by the dispersal of organisms. Often the influence of dispersal interacts with, or even swamps, the influence of local-scale drivers like environmental conditions and species interactions. An emphasis on dispersal and a focus on multi-scale processes enable metacommunity theory to contribute strongly to the advancement of invasion biology. Propagule pressure of invaders has been identified as one of the most important drivers facilitating invasion, so the metacommunity concept, designed to address how dispersal-driven dynamics affect community structure, can directly address many of the central questions of invasion biology. Here we revisit many of the important concepts and paradigms of biological invasions—propagule pressure, biotic resistance, enemy release, functional traits, neonative species, human-assisted transport,—and view those concepts through the lens of metacommunity theory. In doing so, we accomplish several goals. First, we show that work on metacommunities has generated multiple predictions, models, and the tools that can be directly applied to invasion scenarios. Among these predictions is that invasibility of a community should decrease with both local controls on community assembly, and the dispersal rates of native species. Second, we demonstrate that framing biological invasions in metacommunity terms actually unifies several seemingly disparate concepts central to invasion biology. Finally, we recommend several courses of action for the control and management of invasive species that emerge from applying the concepts of metacommunity theory.

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Low litter cover, high light availability and rock cover favour the establishment of Ailanthus altissima in forests in southern Switzerland

NeoBiota ◽

10.3897/neobiota.46.35722 ◽

2019 ◽

Vol 46 ◽

pp. 91-116 ◽

Cited By ~ 2

Author(s):

Simon Knüsel ◽

Marco Conedera ◽

Harald Bugmann ◽

Jan Wunder

Keyword(s):

Tree Species ◽

Native Species ◽

Propagule Pressure ◽

Light Availability ◽

High Light ◽

Forest Composition ◽

Litter Cover ◽

Rock Cover ◽

Lowland Forests ◽

Better Than

Future forest composition is uncertain in many areas due to climate change. The spread of non-native species adds to these uncertainties, particularly in forests recently colonised by novel tree species. To anticipate future forest composition, and thus the provision of ecosystem services, a thorough understanding of the factors influencing the establishment of non-native tree species is essential. We studied the presence and abundance of regeneration of Ailanthusaltissima (Mill.) Swingle in 89 plots on a regular grid in three sites in southern Switzerland to determine the main drivers of its establishment. All sites are located in abandoned, i.e. currently unmanaged stands of Castaneasativa Mill. Propagule pressure is caused by single mature A.altissima that colonised the area ca 40 years ago. We found high rock cover, low litter cover and high light availability to be the most important predictors for the presence of A.altissima regeneration, whereas its abundance was positively influenced by high light availability, low litter cover and high browsing on regeneration of competing species. However, the presence models performed much better than the abundance models. Interestingly, the most important factors favouring the establishment of A.altissima in recently undisturbed sites were found to be similar in a nearby site after a severe forest fire, which suggests a similar establishment strategy after a disturbance as in recently undisturbed forests. Based on our results we expect a further expansion of the species in lowland forests currently dominated by C.sativa, likely controlled primarily by light availability.

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