Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Cryptic seedling herbivory by nocturnal introduced generalists impacts survival, performance of native and exotic plants
Abstract: Although much of the theory on the success of invasive species has been geared at escape from specialist enemies, the impact of introduced generalist invertebrate herbivores on both native and introduced plant species has been underappreciated. The role of nocturnal invertebrate herbivores in structuring plant communities has been examined extensively in Europe, but less so in North America. Many nocturnal generalists (slugs, snails, and earwigs) have been introduced to North America, and 96% of herbivores found during a night census at our California Central Valley site were introduced generalists. We explored the role of these herbivores in the distribution, survivorship, and growth of 12 native and introduced plant species from six families. We predicted that introduced species sharing an evolutionary history with these generalists might be less vulnerable than native plant species. We quantified plant and herbivore abundances within our heterogeneous site and also established herbivore removal experiments in 160 plots spanning the gamut of microhabitats. As 18 collaborators, we checked 2000 seedling sites every day for three weeks to assess nocturnal seedling predation. Laboratory feeding trials allowed us to quantify the palatability of plant species to the two dominant nocturnal herbivores at the site (slugs and earwigs) and allowed us to account for herbivore microhabitat preferences when analyzing attack rates on seedlings. The relationship between local slug abundance and percent cover of five common plant taxa at the field site was significantly negatively associated with the mean palatability of these taxa to slugs in laboratory trials. Moreover, seedling mortality of 12 species in open-field plots was positively correlated with mean palatability of these taxa to both slugs and earwigs in laboratory trials. Counter to expectations, seedlings of native species were neither more vulnerable nor more palatable to nocturnal generalists than those of introduced species. Growth comparison of plants within and outside herbivore exclosures also revealed no differences between native and introduced plant species, despite large impacts of herbivores on growth. Cryptic nocturnal predation on seedlings was common and had large effects on plant establishment at our site. Without intensive monitoring, such predation could easily be misconstrued as poor seedling emergence.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Release from foliar and floral fungal pathogen species does not explain the geographic spread of naturalized North American plants in Europe
Abstract: 1 During the last centuries many alien species have established and spread in new regions, where some of them cause large ecological and economic problems. As one of the main explanations of the spread of alien species, the enemy‐release hypothesis is widely accepted and frequently serves as justification for biological control. 2 We used a global fungus–plant host distribution data set for 140 North American plant species naturalized in Europe to test whether alien plants are generally released from foliar and floral pathogens, whether they are mainly released from pathogens that are rare in the native range, and whether geographic spread of the North American plant species in Europe is associated with release from fungal pathogens. 3 We show that the 140 North American plant species naturalized in Europe were released from 58% of their foliar and floral fungal pathogen species. However, when we also consider fungal pathogens of the native North American host range that in Europe so far have only been reported on other plant species, the estimated release is reduced to 10.3%. Moreover, in Europe North American plants have mainly escaped their rare, pathogens, of which the impact is restricted to few populations. Most importantly and directly opposing the enemy‐release hypothesis, geographic spread of the alien plants in Europe was negatively associated with their release from fungal pathogens. 4 Synthesis. North American plants may have escaped particular fungal species that control them in their native range, but based on total loads of fungal species, release from foliar and floral fungal pathogens does not explain the geographic spread of North American plant species in Europe. To test whether enemy release is the major driver of plant invasiveness, we urgently require more studies comparing release of invasive and non‐invasive alien species from enemies of different guilds, and studies that assess the actual impact of the enemies.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Testing hypotheses for exotic plant success: parallel experiments in the native and introduced ranges
Abstract: A central question in ecology concerns how some exotic plants that occur at low densities in their native range are able to attain much higher densities where they are introduced. This question has remained unresolved in part due to a lack of experiments that assess factors that affect the population growth or abundance of plants in both ranges. We tested two hypotheses for exotic plant success: escape from specialist insect herbivores and a greater response to disturbance in the introduced range. Within three introduced populations in Montana, USA, and three native populations in Germany, we experimentally manipulated insect herbivore pressure and created small-scale disturbances to determine how these factors affect the performance of houndstongue (Cynoglossum officinale), a widespread exotic in western North America. Herbivores reduced plant size and fecundity in the native range but had little effect on plant performance in the introduced range. Small-scale experimental disturbances enhanced seedling recruitment in both ranges, but subsequent seedling survival was more positively affected by disturbance in the introduced range. We combined these experimental results with demographic data from each population to parameterize integral projection population models to assess how enemy escape and disturbance might differentially influence C. officinale in each range. Model results suggest that escape from specialist insects would lead to only slight increases in the growth rate (lambda) of introduced populations. In contrast, the larger response to disturbance in the introduced vs. native range had much greater positive effects on lambda. These results together suggest that, at least in the regions where the experiments were performed, the differences in response to small disturbances by C. officinale contribute more to higher abundance in the introduced range compared to at home. Despite the challenges of conducting experiments on a wide biogeographic scale and the logistical constraints of adequately sampling populations within a range, this approach is a critical step forward to understanding the success of exotic plants.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Arthropod Communities on Native and Nonnative Early Successional Plants
Abstract: ABSTRACT Early successional ruderal plants in North America include numerous native and nonnative species, and both are abundant in disturbed areas. The increasing presence of nonnative plants may negatively impact a critical component of food web function if these species support fewer or a less diverse arthropod fauna than the native plant species that they displace. We compared arthropod communities on six species of common early successional native plants and six species of nonnative plants, planted in replicated native and nonnative plots in a farm field. Samples were taken twice each year for 2 yr. In most arthropod samples, total biomass and abundance were substantially higher on the native plants than on the nonnative plants. Native plants produced as much as five times more total arthropod biomass and up to seven times more species per 100 g of dry leaf biomass than nonnative plants. Both herbivores and natural enemies (predators and parasitoids) predominated on native plants when analyzed separately. In addition, species richness was about three times greater on native than on nonnative plants, with 83 species of insects collected exclusively from native plants, and only eight species present only on nonnatives. These results support a growing body of evidence suggesting that nonnative plants support fewer arthropods than native plants, and therefore contribute to reduced food resources for higher trophic levels.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Does enemy loss cause release? A biogeographical comparison of parasitoid effects on an introduced insect
Abstract: The loss of natural enemies is a key feature of species introductions and is assumed to facilitate the increased success of species in new locales (enemy release hypothesis; ERH). The ERH is rarely tested experimentally, however, and is often assumed from observations of enemy loss. We provide a rigorous test of the link between enemy loss and enemy release by conducting observational surveys and an in situ parasitoid exclusion experiment in multiple locations in the native and introduced ranges of a gall-forming insect, Neuroterus saltatorius, which was introduced poleward, within North America. Observational surveys revealed that the gall-former experienced increased demographic success and lower parasitoid attack in the introduced range. Also, a different composition of parasitoids attacked the gall-former in the introduced range. These observational results show that enemies were lost and provide support for the ERH. Experimental results, however, revealed that, while some enemy release occurred, it was not the sole driver of demographic success. This was because background mortality in the absence of enemies was higher in the native range than in the introduced range, suggesting that factors other than parasitoids limit the species in its native range and contribute to its success in its introduced range. Our study demonstrates the importance of measuring the effect of enemies in the context of other community interactions in both ranges to understand what factors cause the increased demographic success of introduced species. This case also highlights that species can experience very different dynamics when introduced into ecologically similar communities.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Invasive plants escape from suppressive soil biota at regional scales
Abstract: A prominent hypothesis for plant invasions is escape from the inhibitory effects of soil biota. Although the strength of these inhibitory effects, measured as soil feedbacks, has been assessed between natives and exotics in non‐native ranges, few studies have compared the strength of plant–soil feedbacks for exotic species in soils from non‐native versus native ranges. We examined whether 6 perennial European forb species that are widespread invaders in North American grasslands (Centaurea stoebe, Euphorbia esula, Hypericum perforatum, Linaria vulgaris, Potentilla recta and Leucanthemum vulgare) experienced different suppressive effects of soil biota collected from 21 sites across both ranges. Four of the six species tested exhibited substantially reduced shoot biomass in ‘live’ versus sterile soil from Europe. In contrast, North American soils produced no significant feedbacks on any of the invasive species tested indicating a broad scale escape from the inhibitory effects of soil biota. Negative feedbacks generated by European soil varied idiosyncratically among sites and species. Since this variation did not correspond with the presence of the target species at field sites, it suggests that negative feedbacks can be generated from soil biota that are widely distributed in native ranges in the absence of density‐dependent effects. Synthesis. Our results show that for some invasives, native soils have strong suppressive potential, whereas this is not the case in soils from across the introduced range. Differences in regional‐scale evolutionary history among plants and soil biota could ultimately help explain why some exotics are able to occur at higher abundance in the introduced versus native range.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Insect assemblages associated with the exotic riparian shrub Russian olive (Elaeagnaceae), and co-occurring native shrubs in British Columbia, Canada
Abstract: <jats:title>Abstract</jats:title><jats:p>Russian olive (<jats:italic>Elaeagnus angustifolia</jats:italic> Linnaeus; Elaeagnaceae) is an exotic shrub/tree that has become invasive in many riparian ecosystems throughout semi-arid, western North America, including southern British Columbia, Canada. Despite its prevalence and the potentially dramatic impacts it can have on riparian and aquatic ecosystems, little is known about the insect communities associated with Russian olive within its invaded range. At six sites throughout the Okanagan valley of southern British Columbia, Canada, we compared the diversity of insects associated with Russian olive plants to that of insects associated with two commonly co-occurring native plant species: Woods’ rose (<jats:italic>Rosa woodsii</jats:italic> Lindley; Rosaceae) and Saskatoon (<jats:italic>Amelanchier alnifolia</jats:italic> (Nuttall) Nuttall ex Roemer; Rosaceae). Total abundance did not differ significantly among plant types. Family richness and Shannon diversity differed significantly between Woods’ rose and Saskatoon, but not between either of these plant types and Russian olive. An abundance of Thripidae (Thysanoptera) on Russian olive and Tingidae (Hemiptera) on Saskatoon contributed to significant compositional differences among plant types. The families Chloropidae (Diptera), Heleomyzidae (Diptera), and Gryllidae (Orthoptera) were uniquely associated with Russian olive, albeit in low abundances. Our study provides valuable and novel information about the diversity of insects associated with an emerging plant invader of western Canada.</jats:p>
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Can enemy release explain the invasion success of the diploid Leucanthemum vulgare in North America?
Abstract: Abstract Enemy release is a commonly accepted mechanism to explain plant invasions. Both the diploid Leucanthemum vulgare and the morphologically very similar tetraploid Leucanthemum ircutianum have been introduced into North America. To verify which species is more prevalent in North America we sampled 98 Leucanthemum populations and determined their ploidy level. Although polyploidy has repeatedly been proposed to be associated with increased invasiveness in plants, only two of the populations surveyed in North America were the tetraploid L. ircutianum . We tested the enemy release hypothesis by first comparing 20 populations of L. vulgare and 27 populations of L. ircutianum in their native range in Europe, and then comparing the European L. vulgare populations with 31 L. vulgare populations sampled in North America. Characteristics of the site and associated vegetation, plant performance and invertebrate herbivory were recorded. In Europe, plant height and density of the two species were similar but L. vulgare produced more flower heads than L. ircutianum . Leucanthemum vulgare in North America was 17 % taller, produced twice as many flower heads and grew much denser compared to L. vulgare in Europe. Attack rates by root- and leaf-feeding herbivores on L. vulgare in Europe (34 and 75 %) was comparable to that on L. ircutianum (26 and 71 %) but higher than that on L. vulgare in North America (10 and 3 %). However, herbivore load and leaf damage were low in Europe. Cover and height of the co-occurring vegetation was higher in L. vulgare populations in the native than in the introduced range, suggesting that a shift in plant competition may more easily explain the invasion success of L. vulgare than escape from herbivory.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Exotic invasive species in urban wetlands: environmental correlates and implications for wetland management
Abstract: Summary 1. Wetlands in urban regions are subjected to a wide variety of anthropogenic disturbances, many of which may promote invasions of exotic plant species. In order to devise management strategies, the influence of different aspects of the urban and natural environments on invasion and community structure must be understood. 2. The roles of soil variables, anthropogenic effects adjacent to and within the wetlands, and vegetation structure on exotic species occurrence within 21 forested wetlands in north-eastern New Jersey, USA, were compared. The hypotheses were tested that different vegetation strata and different invasive species respond similarly to environmental factors, and that invasion increases with increasing direct human impact, hydrologic disturbance, adjacent residential land use and decreasing wetland area. Canonical correspondence analyses, correlation and logistic regression analyses were used to examine invasion by individual species and overall site invasion, as measured by the absolute and relative number of exotic species in the site flora. 3. Within each stratum, different sets of environmental factors separated exotic and native species. Nutrients, soil clay content and pH, adjacent land use and canopy composition were the most frequently identified factors affecting species, but individual species showed highly individualistic responses to the sets of environmental variables, often responding in opposite ways to the same factor. 4. Overall invasion increased with decreasing area but only when sites > 100 ha were included. Unexpectedly, invasion decreased with increasing proportions of industrial/commercial adjacent land use. 5. The hypotheses were only partially supported; invasion does not increase in a simple way with increasing human presence and disturbance. 6. Synthesis and applications . The results suggest that a suite of environmental conditions can be identified that are associated with invasion into urban wetlands, which can be widely used for assessment and management. However, a comprehensive ecosystem approach is needed that places the remediation of physical alterations from urbanization within a landscape context. Specifically, sediment, inputs and hydrologic changes need to be related to adjoining urban land use and to the overlapping requirements of individual native and exotic species.
Extracted statement — Measure of invasion success: Number of exotic species
Research field: Ecology and Evolutionary Biology
Title: Ecological filtering of exotic plants in an Australian sub-alpine environment
Abstract: Abstract We investigated some of the factors influencing exotic invasion of native sub-alpine plant communities at a site in southeast Australia. Structure, floristic composition and invasibility of the plant communities and attributes of the invasive species were studied. To determine the plant characteristics correlated with invasiveness, we distinguished between roadside invaders, native community invaders and non-invasive exotic species, and compared these groups across a range of traits including functional group, taxonomic affinity, life history, mating system and morphology. Poa grasslands and Eucalyptus-Poa woodlands contained the largest number of exotic species, although all communities studied appeared resilient to invasion by most species. Most community invaders were broad-leaved herbs while roadside invaders contained both herbs and a range of grass species. Over the entire study area the richness and cover of native and exotic herbaceous species were positively related, but exotic herbs were more negatively related to cover of specific functional groups (e.g. trees) than native herbs. Compared with the overall pool of exotic species, those capable of invading native plant communities were disproportionately polycarpic, Asteracean and cross-pollinating. Our data support the hypothesis that strong ecological filtering of exotic species generates an exotic assemblage containing few dominant species and which functionally converges on the native assemblage. These findings contrast with those observed in the majority of invaded natural systems. We conclude that the invasion of closed sub-alpine communities must be viewed in terms of the unique attributes of the invading species, the structure and composition of the invaded communities and the strong extrinsic physical and climatic factors typical of the sub-alpine environment. Nomenclature: Australian Plant Name Index (APNI); http://www.anbg.gov.au/cgi-bin/apni Abbreviations: KNP = Kosciuszko National Park; MRPP = Multi response permutation procedure; VE = Variance explained.
Extracted statement — Measure of resistance/susceptibility: Number of exotic species
Research field: Ecology and Evolutionary Biology
Title: Exotic plant species invade hot spots of native plant diversity
Abstract: Some theories and experimental studies suggest that areas of low plant spe- cies richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m 2 subplots (20 1000-m 2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m 2 subplots (16 1000-m 2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm. At the 1-m 2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m 2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m 2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m 2 plots was explained by the number of native plant species and the total percentage of soil carbon. At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and biodiversity), are invasible in many landscapes; and (2) this pattern may be more closely related to the degree resources are available in native plant communities, independent of species richness. Exotic plant in- vasions in rare habitats and distinctive plant communities pose a significant challenge to land managers and conservation biologists.
Extracted statement — Measure of resistance/susceptibility: Number of exotic species