Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Structural, compositional and trait differences between native- and non-native-dominated grassland patches
Abstract: Summary Non-native species with growth forms that are different from the native flora may alter the physical structure of the area they invade, thereby changing the resources available to resident species. This in turn can select for species with traits suited for the new growing environment. We used adjacent uninvaded and invaded grassland patches to evaluate whether the shift in dominance from a native perennial bunchgrass, Nassella pulchra, to the early season, non-native annual grass, Bromus diandrus, affects the physical structure, available light, plant community composition and community-weighted trait means. Our field surveys revealed that the exotic grass B. diandrus alters both the vertical and horizontal structure creating more dense continuous vegetative growth and dead plant biomass than patches dominated by N. pulchra. These differences in physical structure are responsible for a threefold reduction in available light and likely contribute to the lower diversity, especially of native forbs in B. diandrus-dominated patches. Further, flowering time began earlier and seed size and plant height were higher in B. diandrus patches relative to N. pulchra patches. Our results suggest that species that are better suited (earlier phenology, larger seed size and taller) for low light availability are those that coexist with B. diandrus, and this is consistent with our hypothesis that change in physical structure with B. diandrus invasion is an important driver of community and trait composition. The traits of species able to coexist with invaders are rarely considered when assessing community change following invasion; however, this may be a powerful approach for predicting community change in environments with high anthropogenic pressures, such as disturbance and nutrient enrichment. It also provides a means for selecting species to introduce when trying to enhance native diversity in an otherwise invaded community.
Extracted statement — Ecological Level of evidence: Community
Research field: Ecology and Evolutionary Biology
Title: Feeding behaviour, predatory functional response and trophic interactions of the invasive Chinese mitten crab (Eriocheir sinensis) and signal crayfish (Pacifastacus leniusculus)
Abstract: 1. Freshwaters are subject to particularly high rates of species introductions; hence, invaders increasingly co-occur and may interact to enhance impacts on ecosystem structure and function. As trophic interactions are a key mechanism by which invaders influence communities, we used a combination of approaches to investigate the feeding preferences and community impacts of two globally invasive large benthic decapods that co-occur in freshwaters: the signal crayfish (Pacifastacus leniusculus) and Chinese mitten crab (Eriocheir sinensis). 2. In laboratory preference tests, both consumed similar food items, including chironomids, isopods and the eggs of two coarse fish species. In a comparison of predatory functional responses with a native crayfish Austropotamobius pallipes), juvenile E. sinensis had a greater predatory intensity than the native A. pallipes on the keystone shredder Gammarus pulex, and also displayed a greater preference than P. leniusculus for this prey item. 3. In outdoor mesocosms (n = 16) used to investigate community impacts, the abundance of amphipods, isopods, chironomids and gastropods declined in the presence of decapods, and a decapod >gastropod >periphyton trophic cascade was detected when both species were present. Eriocheir sinensis affected a wider range of animal taxa than P. leniusculus. 4. Stable-isotope and gut-content analysis of wild-caught adult specimens of both invaders revealed a wide and overlapping range of diet items including macrophytes, algae, terrestrial detritus, macroinvertebrates and fish. Both decapods were similarly enriched in 15N and occupied the same trophic level as Ephemeroptera, Odonata and Notonecta. Eriocheir sinensis d13C values were closely aligned with macrophytes indicating a reliance on energy from this basal resource, supported by evidence of direct consumption from gut contents. Pacifastacus leniusculus d13C values were intermediate between those of terrestrial leaf litter and macrophytes, suggesting reliance on both allochthonous and autochthonous energy pathways. 5. Our results suggest that E. sinensis is likely to exert a greater per capita impact on the macroinvertebrate communities in invaded systems than P. leniusculus, with potential indirect effects on productivity and energy flow through the community.
Extracted statement — Ecological Level of evidence: Community
Research field: Ecology and Evolutionary Biology
Title: Enemy damage of exotic plant species is similar to that of natives and increases with productivity
Abstract: In their colonized ranges, exotic plants may be released from some of the herbivores or pathogens of their home ranges but these can be replaced by novel enemies. It is of basic and practical interest to understand which characteristics of invaded communities control accumulation of the new pests. Key questions are whether enemy load on exotic species is smaller than on native competitors as suggested by the enemy release hypothesis (ERH) and whether this difference is most pronounced in resource‐rich habitats as predicted by the resource–enemy release hypothesis (R‐ERH). In 72 populations of 12 exotic invasive species, we scored all visible above‐ground damage morphotypes caused by herbivores and fungal pathogens. In addition, we quantified levels of leaf herbivory and fruit damage. We then assessed whether variation in damage diversity and levels was explained by habitat fertility, by relatedness between exotic species and the native community or rather by native species diversity. In a second part of the study, we also tested the ERH and the R‐ERH by comparing damage of plants in 28 pairs of co‐occurring native and exotic populations, representing nine congeneric pairs of native and exotic species. In the first part of the study, diversity of damage morphotypes and damage levels of exotic populations were greater in resource‐rich habitats. Co‐occurrence of closely related, native species in the community significantly increased the probability of fruit damage. Herbivory on exotics was less likely in communities with high phylogenetic diversity. In the second part of the study, exotic and native congeneric populations incurred similar damage diversity and levels, irrespective of whether they co‐occurred in nutrient‐poor or nutrient‐rich habitats. Synthesis. We identified habitat productivity as a major community factor affecting accumulation of enemy damage by exotic populations. Similar damage levels in exotic and native congeneric populations, even in species pairs from fertile habitats, suggest that the enemy release hypothesis or the R‐ERH cannot always explain the invasiveness of introduced species.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Impact of fire on leaf nutrients, arthropod fauna and herbivory of native and exotic eucalypts in Kings Park, Perth, Western Australia
Abstract: The vegetation of Kings Park, near the centre of Perth, Western Australia, once had an overstorey of Eucalyptus marginata (jarrah) or Eucalyptus gomphocephala (tuart), and many trees still remain in the bushland parts of the Park. Avenues and roadsides have been planted with eastern Australian species, including Eucalyptus cladocalyx (sugar gum) and Eucalyptus botryoides (southern mahogany), both of which have become invasive. The present study examined the effect of a recent burn on the level of herbivory on these native and exotic eucalypts. Leaf damage, shoot extension and number of new leaves were measured on tagged shoots of saplings of each tree species in unburnt and burnt areas over an 8-month period. Leaf macronutrient levels were quantified and the number of arthropods on saplings was measured at the end of the recording period by chemical knockdown. Leaf macronutrients were mostly higher in all four species in the burnt area, and this was associated with generally higher numbers of canopy arthropods and greater levels of leaf damage. It is suggested that the pulse of soil nutrients after the fire resulted in more nutrient-rich foliage, which in turn was more palatable to arthropods. The resulting high levels of herbivory possibly led to reduced shoot extension of E. gomphocephala, E. botryoides and, to a lesser extent, E. cladocalyx. This acts as a negative feedback mechanism that lessens the tendency for lush, post-fire regrowth to outcompete other species of plants. There was no consistent difference in the levels of the various types of leaf damage or of arthropods on the native and the exotic eucalypts, suggesting that freedom from herbivory is not contributing to the invasiveness of the two exotic species.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Herbivory, disease, recruitment limitation, and success of alien and native tree species
Abstract: The Enemies Hypothesis predicts that alien plants have a competitive ad- vantage over native plants because they are often introduced with few herbivores or diseases. To investigate this hypothesis, we transplanted seedlings of the invasive alien tree, Sapium sebiferum (Chinese tallow tree) and an ecologically similar native tree, Celtis laevigata (hackberry), into mesic forest, floodplain forest, and coastal prairie sites in east Texas and manipulated foliar fungal diseases and insect herbivores with fungicidal and insecticidal sprays. As predicted by the Enemies Hypothesis, insect herbivores caused significantly greater damage to untreated Celtis seedlings than to untreated Sapium seedlings. However, contrary to predictions, suppression of insect herbivores caused significantly greater in- creases in survivorship and growth of Sapium seedlings compared to Celtis seedlings. Regressions suggested that Sapium seedlings compensate for damage in the first year but that this greatly increases the risk of mortality in subsequent years. Fungal diseases had no effects on seedling survival or growth. The Recruitment Limitation Hypothesis predicts that the local abundance of a species will depend more on local seed input than on com- petitive ability at that location. To investigate this hypothesis, we added seeds of Celtis and Sapium on and off of artificial soil disturbances at all three sites. Adding seeds increased the density of Celtis seedlings and sometimes Sapium seedlings, with soil disturbance only affecting density of Celtis. Together the results of these experiments suggest that the success of Sapium may depend on high rates of seed input into these ecosystems and high growth potential, as well as performance advantages of seedlings caused by low rates of herbivory.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Enemy release? An experiment with congeneric plant pairs and diverse above- and belowground enemies
Abstract: Several hypotheses proposed to explain the success of introduced species focus on altered interspecific interactions. One of the most prominent, the Enemy Release Hypothesis, posits that invading species benefit compared to their native counterparts if they lose their herbivores and pathogens during the invasion process. We previously reported on a common garden experiment (from 2002) in which we compared levels of herbivory between 30 taxonomically paired native and introduced old-field plants. In this phyloge- netically controlled comparison, herbivore damage tended to be higher on introduced than on native plants. This striking pattern, the opposite of current theory, prompted us to further investigate herbivory and several other interspecific interactions in a series of linked ex- periments with the same set of species. Here we show that, in these new experiments, introduced plants, on average, received less insect herbivory and were subject to half the negative soil microbial feedback compared to natives; attack by fungal and viral pathogens also tended to be reduced on introduced plants compared to natives. Although plant traits (foliar C:N, toughness, and water content) suggested that introduced species should be less resistant to generalist consumers, they were not consistently more heavily attacked. Finally, we used meta-analysis to combine data from this study with results from our previous work to show that escape generally was inconsistent among guilds of enemies: there were few instances in which escape from multiple guilds occurred for a taxonomic pair, and more cases in which the patterns of escape from different enemies canceled out. Our examination of multiple interspecific interactions demonstrates that escape from one guild of enemies does not necessarily imply escape from other guilds. Because the effects of each guild are likely to vary through space and time, the net effect of all enemies is also likely to be variable. The net effect of these interactions may create ''invasion opportunity windows'': times when introduced species make advances in native communities.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Invasive exotic plants suffer less herbivory than non-invasive exotic plants
Abstract: We surveyed naturally occurring leaf herbivory in nine invasive and nine non-invasive exotic plant species sampled in natural areas in Ontario, New York and Massachusetts, and found that invasive plants experienced, on average, 96% less leaf damage than non-invasive species. Invasive plants were also more taxonomically isolated than non-invasive plants, belonging to families with 75% fewer native North American genera. However, the relationship between taxonomic isolation at the family level and herbivory was weak. We suggest that invasive plants may possess novel phytochemicals with anti-herbivore properties in addition to allelopathic and anti-microbial characteristics. Herbivory could be employed as an easily measured predictor of the likelihood that recently introduced exotic plants may become invasive.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: The interaction between soil nutrients and leaf loss during early 14 establishment in plant invasion
Abstract: Nitrogen availability affects both plant growth and the preferences of herbivores. We hypothesized that an interaction between these two factors could affect the early establishment of native and exotic species differently, promoting invasion in natural systems. Taxonomically paired native and invasive species (Acer platanoides, Acer rubrum, Lonicera maackii, Diervilla lonicera, Celastrus orbiculata, Celastrus scandens, Elaeagnus umbellata, Ceanothus americanus, Ampelopsis brevipedunculata, and Vitis riparia) were grown in relatively high-resource (hardwood forests) and low-resource (pine barrens) communities on Long Island, New York, for a period of 3 months. Plants were grown in ambient and nitrogen-enhanced conditions in both communities. Nitrogen additions produced an average 12% initial increase in leaf number of all plants. By the end of the experiment, invasive species outperformed native species in nitrogen-enhanced plots in hardwood forests, where all plants experienced increased damage relative to control plots. Native species experienced higher overall amounts of damage in hardwood forests, losing, on average, 45% more leaves than exotic species, and only native species experienced a decline in growth rates (32% compared with controls). In contrast, in pine barrens, there were no differences in damage and no differences in performance between native and invasive plants. Our results suggest that unequal damage by natural enemies may play a role in determining community composition by shifting the competitive advantage to exotic species in nitrogen-enhanced environments. FOR. SCI. 53(6):701-709.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Experimental field comparison of native and non-native maple seedlings: natural enemies, ecophysiology, growth and survival
Abstract: 1 Acer platanoides (Norway maple) is an important non‐native invasive canopy tree in North American deciduous forests, where native species diversity and abundance are greatly reduced under its canopy. We conducted a field experiment in North American forests to compare planted seedlings of A. platanoides and Acer saccharum (sugar maple), a widespread, common native that, like A. platanoides, is shade tolerant. Over two growing seasons in three forests we compared multiple components of seedling success: damage from natural enemies, ecophysiology, growth and survival. We reasoned that equal or superior performance by A. platanoides relative to A. saccharum indicates seedling characteristics that support invasiveness, while inferior performance indicates potential barriers to invasion. 2 Acer platanoides seedlings produced more leaves and allocated more biomass to roots, A. saccharum had greater water use efficiency, and the two species exhibited similar photosynthesis and first‐season mortality rates. Acer platanoides had greater winter survival and earlier spring leaf emergence, but second‐season mortality rates were similar. 3 The success of A. platanoides seedlings was not due to escape from natural enemies, contrary to the enemy release hypothesis. Foliar insect herbivory and disease symptoms were similarly high for both native and non‐native, and seedling biomass did not differ. Rather, A. platanoides compared well with A. saccharum because of its equivalent ability to photosynthesize in the low light herb layer, its higher leaf production and greater allocation to roots, and its lower winter mortality coupled with earlier spring emergence. Its only potential barrier to seedling establishment, relative to A. saccharum, was lower water use efficiency, which possibly could hinder its invasion into drier forests. 4 The spread of non‐native canopy trees poses an especially serious problem for native forest communities, because canopy trees strongly influence species in all forest layers. Success at reaching the canopy depends on a tree's ecology in previous life‐history stages, particularly as a vulnerable seedling, but little is known about seedling characteristics that promote non‐native tree invasion. Experimental field comparison with ecologically successful native trees provides insight into why non‐native trees succeed as seedlings, which is a necessary stage on their journey into the forest canopy.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: When there is no escape: The effects of natural enemies on native, invasive, and noninvasive plants
Abstract: An important question in the study of biological invasions is the degree to which successful invasion can be explained by release from control by natural enemies. Natural enemies dominate explanations of two alternate phenomena: that most introduced plants fail to establish viable populations (biotic resistance hypothesis) and that some introduced plants become noxious invaders (natural enemies hypothesis). We used a suite of 18 phylogenetically related native and nonnative clovers (Trifolium and Medicago) and the foliar pathogens and invertebrate herbivores that attack them to answer two questions. Do native species suffer greater attack by natural enemies relative to introduced species at the same site? Are some introduced species excluded from native plant communities because they are susceptible to local natural enemies? We address these questions using three lines of evidence: (1) the frequency of attack and composition of fungal pathogens and herbivores for each clover species in four years of common garden experiments, as well as susceptibility to inoculation with a common pathogen; (2) the degree of leaf damage suffered by each species in common garden experiments; and (3) fitness effects estimated using correlative approaches and pathogen removal experiments. Introduced species showed no evidence of escape from pathogens, being equivalent to native species as a group in terms of infection levels, susceptibility, disease prevalence, disease severity (with more severe damage on introduced species in one year), the influence of disease on mortality, and the effect of fungicide treatment on mortality and biomass. In contrast, invertebrate herbivores caused more damage on native species in two years, although the influence of herbivore attack on mortality did not differ between native and introduced species. Within introduced species, the predictions of the biotic resistance hypothesis were not supported: the most invasive species showed greater infection, greater prevalence and severity of disease, greater prevalence of herbivory, and greater effects of fungicide on biomass and were indistinguishable from noninvasive introduced species in all other respects. Therefore, although herbivores preferred native over introduced species, escape from pest pressure cannot be used to explain why some introduced clovers are common invaders in coastal prairie while others are not.
Extracted statement — Indicator for enemy release: Damage
Research field: Ecology and Evolutionary Biology
Title: Tolerance to herbivory, and not resistance, may explain differential success of invasive, naturalized, and native North American temperate vines
Abstract: Numerous hypotheses suggest that natural enemies can influence the dynamics of biological invasions. Here, we use a group of 12 related native, invasive, and naturalized vines to test the relative importance of resistance and tolerance to herbivory in promoting biological invasions. In a field experiment in Long Island, New York, we excluded mammal and insect herbivores and examined plant growth and foliar damage over two growing seasons. This novel approach allowed us to compare the relative damage from mammal and insect herbivores and whether damage rates were related to invasion. In a greenhouse experiment, we simulated herbivory through clipping and measured growth response. After two seasons of excluding herbivores, there was no difference in relative growth rates among invasive, naturalized, and native woody vines, and all vines were susceptible to damage from mammal and insect herbivores. Thus, differential attack by herbivores and plant resistance to herbivory did not explain invasion success of these species. In the field, where damage rates were high, none of the vines were able to fully compensate for damage from mammals. However, in the greenhouse, we found that invasive vines were more tolerant of simulated herbivory than native and naturalized relatives. Our results indicate that invasive vines are not escaping herbivory in the novel range, rather they are persisting despite high rates of herbivore damage in the field. While most studies of invasive plants and natural enemies have focused on resistance, this work suggests that tolerance may also play a large role in facilitating invasions.
Extracted statement — Indicator for enemy release: Damage