Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Disturbance-mediated competition and the spread of Phragmites australis in a coastal marsh
Abstract: In recent decades the grass Phragmites australis has been aggressively in- vading coastal, tidal marshes of North America, and in many areas it is now considered a nuisance species. While P. australis has historically been restricted to the relatively benign upper border of brackish and salt marshes, it has been expanding seaward into more phys- iologically stressful regions. Here we test a leading hypothesis that the spread of P. australis is due to anthropogenic modification of coastal marshes. We did a field experiment along natural borders between stands of P. australis and the other dominant grasses and rushes (i.e., matrix vegetation) in a brackish marsh in Rhode Island, USA. We applied a pulse disturbance in one year by removing or not removing neighboring matrix vegetation and adding three levels of nutrients (specifically nitrogen) in a factorial design, and then we monitored the aboveground performance of P. australis and the matrix vegetation. Both disturbances increased the density, height, and biomass of shoots of P. australis, and the effects of fertilization were more pronounced where matrix vegetation was removed. Clear- ing competing matrix vegetation also increased the distance that shoots expanded and their reproductive output, both indicators of the potential for P. australis to spread within and among local marshes. In contrast, the biomass of the matrix vegetation decreased with increasing severity of disturbance. Disturbance increased the total aboveground production of plants in the marsh as matrix vegetation was displaced by P. australis. A greenhouse experiment showed that, with increasing nutrient levels, P. australis allocates proportionally more of its biomass to aboveground structures used for spread than to belowground struc- tures used for nutrient acquisition. Therefore, disturbances that enrich nutrients or remove competitors promote the spread of P. australis by reducing belowground competition for nutrients between P. australis and the matrix vegetation, thus allowing P. australis, the largest plant in the marsh, to expand and displace the matrix vegetation. Reducing nutrient load and maintaining buffers of matrix vegetation along the terrestrial-marsh ecotone will, therefore, be important methods of control for this nuisance species.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Shoreline development drives invasion of Phragmites australis and the loss of plant diversity on New England salt marshes
Abstract: Abstract: The reed Phragmites australis Cav. is aggressively invading salt marshes along the Atlantic Coast of North America. We examined the interactive role of habitat alteration (i.e., shoreline development) in driving this invasion and its consequences for plant richness in New England salt marshes. We surveyed 22 salt marshes in Narragansett Bay, Rhode Island, and quantified shoreline development, Phragmites cover, soil salinity, and nitrogen availability. Shoreline development, operationally defined as removal of the woody vegetation bordering marshes, explained >90% of intermarsh variation in Phragmites cover. Shoreline development was also significantly correlated with reduced soil salinities and increased nitrogen availability, suggesting that removing woody vegetation bordering marshes increases nitrogen availability and decreases soil salinities, thus facilitating Phragmites invasion. Soil salinity (64%) and nitrogen availability (56%) alone explained a large proportion of variation in Phragmites cover, but together they explained 80% of the variation in Phragmites invasion success. Both univariate and aggregate (multidimensional scaling) analyses of plant community composition revealed that Phragmites dominance in developed salt marshes resulted in an almost three‐fold decrease in plant species richness. Our findings illustrate the importance of maintaining integrity of habitat borders in conserving natural communities and provide an example of the critical role that local conservation can play in preserving these systems. In addition, our findings provide ecologists and natural resource managers with a mechanistic understanding of how human habitat alteration in one vegetation community can interact with species introductions in adjacent communities (i.e., flow‐on or adjacency effects) to hasten ecosystem degradation.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Movement, colonization, and establishment success of a planthopper of prairie potholes, Delphacodes scolochloa (Hemiptera: Delphacidae)
Abstract: Abstract 1. Movement, and particularly the colonisation of new habitat patches, remains one of the least known aspects of the life history and ecology of the vast majority of species. Here, a series of experiments was conducted to rectify this problem with Delphacodes scolochloa Cronin & Wilson, a wing‐dimorphic planthopper of the North American Great Plains.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Determinants of vertebrate invasion success in Europe and North America
Abstract: Species that are frequently introduced to an exotic range have a high potential of becoming invasive. Besides propagule pressure, however, no other generally strong determinant of invasion success is known. Although evidence has accumulated that human affiliates (domesticates, pets, human commensals) also have high invasion success, existing studies do not distinguish whether this success can be completely explained by or is partly independent of propagule pressure. Here, we analyze both factors independently, propagule pressure and human affiliation. We also consider a third factor directly related to humans, hunting, and 17 traits on each species' population size and extent, diet, body size, and life history. Our dataset includes all 2362 freshwater fish, mammals, and birds native to Europe or North America. In contrast to most previous studies, we look at the complete invasion process consisting of (1) introduction, (2) establishment, and (3) spread. In this way, we not only consider which of the introduced species became invasive but also which species were introduced. Of the 20 factors tested, propagule pressure and human affiliation were the two strongest determinants of invasion success across all taxa and steps. This was true for multivariate analyses that account for intercorrelations among variables as well as univariate analyses, suggesting that human affiliation influenced invasion success independently of propagule pressure. Some factors affected the different steps of the invasion process antagonistically. For example, game species were much more likely to be introduced to an exotic continent than nonhunted species but tended to be less likely to establish themselves and spread. Such antagonistic effects show the importance of considering the complete invasion process.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: The relative importance of latitude matching and propagule pressure in the colonization success of an invasive forb
Abstract: Factors that influence the early stages of invasion can be critical to invasion success, yet are seldom studied. In particular, broad pre-adaptation to recipient climate may importantly influence early colonization success, yet few studies have explicitly examined this. I performed an experiment to determine how similarity between seed source and transplant site latitude, as a general indicator of pre-adaptation to climate, interacts with propagule pressure (100, 200 and 400 seeds/pot) to influence early colonization success of the widespread North American weed, St. John's wort Hypericum perforatum. Seeds originating from seven native European source populations were sown in pots buried in the ground in a field in western Montana. Seed source populations were either similar or divergent in latitude to the recipient transplant site. Across seed density treatments, the match between seed source and recipient latitude did not affect the proportion of pots colonized or the number of individual colonists per pot. In contrast, propagule pressure had a significant and positive effect on colonization. These results suggest that propagules from many climatically divergent source populations can be viable invaders.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Effects of soil fungi, disturbance and propagule pressure on exotic plant recruitment and establishment at home and abroad
Abstract: Biogeographic experiments that test how multiple interacting factors influence exotic plant abundance in their home and recipient communities are remarkably rare. We examined the effects of soil fungi, disturbance and propagule pressure on seed germination, seedling recruitment and adult plant establishment of the invasive Centaurea stoebe in its native European and non‐native North American ranges. Centaurea stoebe can establish virtual monocultures in parts of its non‐native range, but occurs at far lower abundances where it is native. We conducted parallel experiments at four European and four Montana (USA) grassland sites with all factorial combinations of ± suppression of soil fungi, ±disturbance and low versus high knapweed propagule pressure [100 or 300 knapweed seeds per 0.3 m × 0.3 m plot (1000 or 3000 per m2)]. We also measured germination in buried bags containing locally collected knapweed seeds that were either treated or not with fungicide. Disturbance and propagule pressure increased knapweed recruitment and establishment, but did so similarly in both ranges. Treating plots with fungicides had no effect on recruitment or establishment in either range. However, we found: (i) greater seedling recruitment and plant establishment in undisturbed plots in Montana compared to undisturbed plots in Europe and (ii) substantially greater germination of seeds in bags buried in Montana compared to Europe. Also, across all treatments, total plant establishment was greater in Montana than in Europe. Synthesis. Our results highlight the importance of simultaneously examining processes that could influence invasion in both ranges. They indicate that under ‘background’ undisturbed conditions, knapweed recruits and establishes at greater abundance in Montana than in Europe. However, our results do not support the importance of soil fungi or local disturbances as mechanisms for knapweed's differential success in North America versus Europe.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Propagule pressure and resource availability determine plant community invasibility in a temperate forest understorey
Abstract: Few field experiments have examined the effects of both resource availability and propagule pressure on plant community invasibility. Two non-native forest species, a herb and a shrub (Hesperis matronalis and Rhamnus cathartica, respectively), were sown into 60 1-m 2 sub-plots distributed across three plots. These contained reconstructed native plant communities in a replaced surface soil layer in a North American forest interior. Resource availability and propagule pressure were manipulated as follows: understorey light level (shaded/unshaded), nutrient availability (control/fertilized), and seed pressures of the two non-native species (control/low/high). Hesperis and Rhamnus cover and the above-ground biomass of Hesperis were significantly higher in shaded sub-plots and at greater propagule pressures. Similarly, the above-ground biomass of Rhamnus was significantly increased with propagule pressure, although this was a function of density. In contrast, of species that seeded into plots from the surrounding forest during the growing season, the non-native species had significantly greater cover in unshaded sub-plots. Plants in these unshaded sub-plots were significantly taller than plants in shaded sub-plots, suggesting a greater fitness. Total and non-native species richness varied significantly among plots indicating the importance of fine-scale dispersal patterns. None of the experimental treatments influenced native species. Since the forest seed bank in our study was colonized primarily by non-native ruderal species that dominated understorey vegetation, the management of invasions by non-native species in forest understoreys will have to address factors that influence light levels and dispersal pathways.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Interactions among aliens: apparent replacement of one exotic species by another
Abstract: Although many studies have documented the impact of invasive species on indigenous flora and fauna, few have rigorously examined interactions among invaders and the potential for one exotic species to replace another. European green crabs (Carcinus maenas), once common in rocky intertidal habitats of southern New England, have recently declined in abundance coincident with the invasion of the Asian shore crab (Hemigrapsus sanguineus). Over a four-year period in the late 1990s we documented a significant (40- 90%) decline in green crab abundance and a sharp (10-fold) increase in H. sanguineus at three sites in southern New England. Small, newly recruited green crabs had a significant risk of predation when paired with larger H. sanguineus in the laboratory, and recruitment of 0-yr C. maenas was reduced by H. sanguineus as well as by larger conspecifics in field- deployed cages (via predation and cannibalism, respectively). In contrast, recruitment of 0-yr H. sanguineus was not affected by larger individuals of either crab species during the same experiments. The differential susceptibility of C. maenas and H. sanguineus recruits to predation and cannibalism likely contributed to the observed decrease in C. maenas abundance and the almost exponential increase in H. sanguineus abundance during the period of study, While the Asian shore crab is primarily restricted to rocky intertidal habitats, C. maenas is found intertidally, subtidally, and in a range of substrate types in New England. Thus, the apparent replacement of C. maenas by H. sanguineus in rocky intertidal habitats of southern New England may not ameliorate the economic and ecological impacts attributed to green crab populations in other habitats of this region. For example, field experiments indicate that predation pressure on a native bivalve species (Mytilus edulis) has not nec- essarily decreased with the declines of C. maenas. While H. sanguineus has weaker per capita effects than C. maenas, its densities greatly exceed those of C. maenas at present and its population-level effects are likely comparable to the past effects of C. maenas. The Carcinus-Hemigrapsus interactions documented here are relevant in other parts of the world where green crabs and grapsid crabs interact, particularly on the west coast of North America where C. maenas has recently invaded and co-occurs with two native Hemigrapsus species.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Inhibition between invasives: a newly introduced predator moderates the impacts of a previously established invasive predator
Abstract: 1. With continued globalization, species are being transported and introduced into novel habitats at an accelerating rate. Interactions between invasive species may provide important mechanisms that moderate their impacts on native species. 2. The European green crab Carcinus maenas is an aggressive predator that was introduced to the east coast of North America in the mid-1800 s and is capable of rapid consumption of bivalve prey. A newer invasive predator, the Asian shore crab Hemigrapsus sanguineus, was first discovered on the Atlantic coast in the 1980s, and now inhabits many of the same regions as C. maenas within the Gulf of Maine. Using a series of field and laboratory investigations, we examined the consequences of interactions between these predators. 3. Density patterns of these two species at different spatial scales are consistent with negative interactions. As a result of these interactions, C. maenas alters its diet to consume fewer mussels, its preferred prey, in the presence of H. sanguineus. Decreased mussel consumption in turn leads to lower growth rates for C. maenas, with potential detrimental effects on C. maenas populations. 4. Rather than an invasional meltdown, this study demonstrates that, within the Gulf of Maine, this new invasive predator can moderate the impacts of the older invasive predator.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Does whirling disease mediate hybridization between a native and nonnative trout?
Abstract: AbstractThe spread of nonnative species over the last century has profoundly altered freshwater ecosystems, resulting in novel species assemblages. Interactions between nonnative species may alter their impacts on native species, yet few studies have addressed multispecies interactions. The spread of whirling disease, caused by the nonnative parasite Myxobolus cerebralis, has generated declines in wild trout populations across western North America. Westslope Cutthroat Trout Oncorhynchus clarkii lewisi in the northern Rocky Mountains are threatened by hybridization with introduced Rainbow Trout O. mykiss. Rainbow Trout are more susceptible to whirling disease than Cutthroat Trout and may be more vulnerable due to differences in spawning location. We hypothesized that the presence of whirling disease in a stream would (1) reduce levels of introgressive hybridization at the site scale and (2) limit the size of the hybrid zone at the whole-stream scale. We measured levels of introgression and the spatial ext...
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Biodiversity ffects and rates of spred of nonnative eucalypt woodlands in central California
Abstract: Woodlands comprised of planted, nonnative trees are increasing in extent globally, while native woodlands continue to decline due to human activities. The ecological impacts of planted woodlands may include changes to the communities of understory plants and animals found among these nonnative trees relative to native woodlands, as well as invasion of adjacent habitat areas through spread beyond the originally planted areas. Eucalypts (Eucalyptus spp.) are among the most widely planted trees worldwide, and are very common in California, USA. The goals of our investigation were to compare the biological communities of nonnative eucalypt woodlands to native oak woodlands in coastal central California, and to examine whether planted eucalypt groves have increased in size over the past decades. We assessed site and habitat attributes and characterized biological communities using understory plant, ground-dwelling arthropod, amphibian, and bird communities as indicators. Degree of difference between native and nonnative woodlands depended on the indicator used. Eucalypts had significantly greater canopy height and cover, and significantly lower cover by perennial plants and species richness of arthropods than oaks. Community composition of arthropods also differed significantly between eucalypts and oaks. Eucalypts had marginally significantly deeper litter depth, lower abundance of native plants with ranges limited to western North America, and lower abundance of amphibians. In contrast to these differences, eucalypt and oak groves had very similar bird community composition, species richness, and abundance. We found no evidence of "invasional meltdown," documenting similar abundance and richness of nonnatives in eucalypt vs. oak woodlands. Our time-series analysis revealed that planted eucalypt groves increased 271% in size, on average, over six decades, invading adjacent areas. Our results inform science-based management of California woodlands, revealing that while bird communities would probably not be affected by restoration of eucalypt to oak woodlands, such a restoration project would not only stop the spread of eucalypts into adjacent habitats but would also enhance cover by western North American native plants and perennials, enhance amphibian abundance, and increase arthropod richness.
Extracted statement — Continent: North America
Research field: Ecology and Evolutionary Biology
Title: Scaling the consequences of interactions between invaders from the indivdual to the population level
Abstract: Abstract The impact of human‐induced stressors, such as invasive species, is often measured at the organismal level, but is much less commonly scaled up to the population level. Interactions with invasive species represent an increasingly common source of stressor in many habitats. However, due to the increasing abundance of invasive species around the globe, invasive species now commonly cause stresses not only for native species in invaded areas, but also for other invasive species. I examine the European green crab Carcinus maenas, an invasive species along the northeast coast of North America, which is known to be negatively impacted in this invaded region by interactions with the invasive Asian shore crab Hemigrapsus sanguineus. Asian shore crabs are known to negatively impact green crabs via two mechanisms: by directly preying on green crab juveniles and by indirectly reducing green crab fecundity via interference (and potentially exploitative) competition that alters green crab diets. I used life‐table analyses to scale these two mechanistic stressors up to the population level in order to examine their relative impacts on green crab populations. I demonstrate that lost fecundity has larger impacts on per capita population growth rates, but that both predation and lost fecundity are capable of reducing population growth sufficiently to produce the declines in green crab populations that have been observed in areas where these two species overlap. By scaling up the impacts of one invader on a second invader, I have demonstrated that multiple documented interactions between these species are capable of having population‐level impacts and that both may be contributing to the decline of European green crabs in their invaded range on the east coast of North America.
Extracted statement — Continent: North America