Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: Propagule pressure drives establishment of introduced freshwater fish: quantitative evidence from an irrigation network
Abstract: Propagule pressure is recognized as a fundamental driver of freshwater fish invasions, though few studies have quantified its role. Natural experiments can be used to quantify the role of this factor relative to others in driving establishment success. An irrigation network in South Africa takes water from an inter-basin water transfer (IBWT) scheme to supply multiple small irrigation ponds. We compared fish community composition upstream, within, and downstream of the irrigation network, to show that this system is a unidirectional dispersal network with a single immigration source. We then assessed the effect of propagule pressure and biological adaptation on the colonization success of nine fish species across 30 recipient ponds of varying age. Establishing species received significantly more propagules at the source than did incidental species, while rates of establishment across the ponds displayed a saturation response to propagule pressure. This shows that propagule pressure is a significant driver of establishment overall. Those species that did not establish were either extremely rare at the immigration source or lacked the reproductive adaptations to breed in the ponds. The ability of all nine species to arrive at some of the ponds illustrates how long-term continuous propagule pressure from IBWT infrastructure enables range expansion of fishes. The quantitative link between propagule pressure and success and rate of population establishment confirms the driving role of this factor in fish invasion ecology.
Extracted statement — Measure of invasion success: Establishment
Research field: Ecology and Evolutionary Biology
Title: Responses of exotic plant species to fires in Pinus ponderosa forests in northern Arizona
Abstract: . Changes in disturbance due to fire regime in southwestern Pinus ponderosa forests over the last century have led to dense forests that are threatened by widespread fire. It has been shown in other studies that a pulse of native, early-seral opportunistic species typically follow such disturbance events. With the growing importance of exotic plants in local flora, however, these exotics often fill this opportunistic role in recovery. We report the effects of fire severity on exotic plant species following three widespread fires of 1996 in northern Arizona P. ponderosa forests. Species richness and abundance of all vascular plant species, including exotics, were higher in burned than nearby unburned areas. Exotic species were far more important, in terms of cover, where fire severity was highest. Species present after wildfires include those of the pre-disturbed forest and new species that could not be predicted from above-ground flora of nearby unburned forests.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Factors influencing dynamics of two invasive C-4 grasses in seasonally dry Hawaiian woodlands
Abstract: The introduced C4 bunchgrass, Schizachyrium condensatum, is abundant in unburned, seasonally dry woodlands on the island of Hawaii, where it promotes the spread of fire. After fire, it is partially replaced by Melinis minutiflora, another invasive C4 grass. Seed bank surveys in unburned woodland showed that Melinis seed is present in locations without adult plants. Using a combination of germination tests and seedling outplant ex- periments, we tested the hypothesis that Melinis was unable to invade the unburned wood- land because of nutrient and/or light limitation. We found that Melinis germination and seedling growth are depressed by the low light levels common under Schizachyrium in unburned woodland. Outplanted Melinis seedlings grew rapidly to flowering and persisted for several years in unburned woodland without nutrient additions, but only if Schizachyrium individuals were removed. Nutrients alone did not facilitate Melinis establishment. Competition between Melinis and Schizachyrium naturally occurs when individuals of both species emerge from the seed bank simultaneously, or when seedlings of one species emerge in sites already dominated by individuals of the other species. When both species are grown from seed, we found that Melinis consistently outcompetes Schizachyrium, re- gardless of light or nutrient treatments. When seeds of Melinis were added to pots with well-established Schizachyrium (and vice versa), Melinis eventually invaded and overgrew adult Schizachyrium under high, but not low, nutrients. By contrast, Schizachyrium could not invade established Melinis pots regardless of nutrient level. A field experiment dem- onstrated that Schizachyrium individuals are suppressed by Melinis in burned sites through competition for both light and nutrients. Overall, Melinis is a dominant competitor over Schizachyrium once it becomes estab- lished, whether in a pot or in the field. We believe that the dominance of Schizachyrium, rather than Melinis, in the unburned woodland is the result of asymmetric competition due to the prior establishment of Schizachyrium in these sites. If Schizachyrium were not present, the unburned woodland could support dense stands of Melinis. Fire disrupts the priority effect of Schizachyrium and allows the dominant competitor (Melinis) to enter the system where it eventually replaces Schizachyrium through resource competition.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Anthropogenic fires increase alien and native annual species in the Chilean coastal matorral
Abstract: Aim We tested the hypothesis that anthropogenic fires favour the successful establishment of alien annual species to the detriment of natives in the Chilean coastal matorral.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Alien Grass Invasion and Fire In the Seasonal Submontane Zone of Hawaii
Abstract: Island ecosystems are notably susceptible to biological invasions (Elton 1958), and the Hawaiian islands in particular have been colonized by many introduced species (Loope and Mueller-Dombois 1989). Introduced plants now dominate extensive areas of the Hawaiian Islands, and 86 species of alien plants are presently considered to pose serious threats to Hawaiian communities and ecosystems (Smith 1985). Among the most important invasive plants are several species of tropical and subtropical grasses that use the C4 photosynthetic pathway. These grasses now dominate extensive areas of dry and seasonally dry habitats in Hawai'i. They may compete with native species, and they have also been shown to alter hydrological properties in the areas they invade (MuellerDombois 1973). Most importantly, alien grasses can introduce fire into areas where it was previously rare or absent (Smith 1985), thereby altering the structure and functioning of previously native-dominated ecosystems. Many of these grasses evolved in fire-affected areas and have mechanisms for surviving and recovering rapidly from fire (Vogl 1975, Christensen 1985), while most native species in Hawai'i have little background with fire (Mueller-Dombois 1981) and hence few or no such mechanisms. Consequently, grass invasion could initiate a grass/fire cycle whereby invading grasses promote fire, which in turn favors alien grasses over native species. Such a scenario has been suggested in a number of areas, including Latin America, western North America, Australia, and Hawai'i (Parsons 1972, Smith 1985, Christensen and Burrows 1986, Mack 1986, MacDonald and Frame 1988). In most of these cases, land clearing by humans initiates colonization by alien grasses, and the grass/fire cycle then leads to their persistence. In Hawai'i and perhaps other areas, however, grass invasion occurs without any direct human intervention. Where such invasions initiate a grass/fire cy-
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: The short-term responses of small mammals to wildfire in semiarid mallee shrubland, Australia
Abstract: Context. Wildfire is a major driver of the structure and function of mallee eucalypt- and spinifex-dominated landscapes. Understanding how fire influences the distribution of biota in these fire-prone environments is essential for effective ecological and conservation-based management. Aims. We aimed to (1) determine the effects of an extensive wildfire (118 000 ha) on a small mammal community in the mallee shrublands of semiarid Australia and (2) assess the hypothesis that the fire-response patterns of small mammals can be predicted by their life-history characteristics. Methods. Small-mammal surveys were undertaken concurrently at 26 sites: once before the fire and on four occasions following the fire (including 14 sites that remained unburnt). We documented changes in small-mammal occurrence before and after the fire, and compared burnt and unburnt sites. In addition, key components of vegetation structure were assessed at each site. Key results. Wildfire had a strong influence on vegetation structure and on the occurrence of small mammals. The mallee ningaui, Ningaui yvonneae, a dasyurid marsupial, showed a marked decline in the immediate post-fire environment, corresponding with a reduction in hummock-grass cover in recently burnt vegetation. Species richness of native small mammals was positively associated with unburnt vegetation, although some species showed no clear response to wildfire. Conclusions. Our results are consistent with the contention that mammal responses to fire are associated with their known life-history traits. The species most strongly affected by wildfire, N. yvonneae, has the most specific habitat requirements and restricted life history of the small mammals in the study area. The only species positively associated with recently burnt vegetation, the introduced house mouse, Mus domesticus, has a flexible life history and non-specialised resource requirements. Implications. Maintaining sources for recolonisation after large-scale wildfires will be vital to the conservation of native small mammals in mallee ecosystems.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Fire effects on plant diversity in serpentine vs. sandstone chaparral
Abstract: Fire contributes to the maintenance of species diversity in many plant com- munities, but few studies have compared its impacts in similar communities that vary in such attributes as soils and productivity. We compared how a wildfire affected plant diversity in chaparral vegetation on serpentine and sandstone soils. We hypothesized that because biomass and cover are lower in serpentine chaparral, space and light are less limiting, and therefore postfire increases in plant species diversity would be lower than in sandstone chaparral. In 40 pairs of burned and unburned 250-m 2 plots, we measured changes in the plant community after a fire for three years. The diversity of native and exotic species increased more in response to fire in sandstone than serpentine chaparral, at both the local (plot) and regional (whole study) scales. In serpentine compared with sandstone chaparral, specialized fire-dependent species were less prevalent, mean fire severity was lower, mean time since last fire was longer, postfire shrub recruitment was lower, and regrowth of biomass was slower. Within each chaparral type, the responses of diversity to fire were positively correlated with prefire shrub cover and with a number of measures of soil fertility. Fire severity was negatively related to the postfire change in diversity in sandstone chaparral, and unimodally related to the postfire change in diversity in serpentine chaparral. Our results suggest that the effects of fire on less productive plant communities like serpentine chaparral may be less pronounced, although longer lasting, than the effects of fire on similar but more productive communities.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Pre-fire fuel reduction treatments influence plant communities and exotic species 9 years after a large wildfire
Abstract: Questions: How did post-wildfire understorey plant community response, including exotic species response, differ between pre-fire treated areas that were less severely burned, and pre-fire untreated areas that were more severely burned? Were these differences consistent through time? Location: East-central Arizona, southwestern US. Methods: We used a multi-year data set from the 2002 Rodeo–Chediski Fire to detect post-fire trends in plant community response in burned ponderosa pine forests. Within the burn perimeter, we examined the effects of pre-fire fuels treatments on post-fire vegetation by comparing paired treated and untreated sites on the Apache-Sitgreaves National Forest. We sampled these paired sites in 2004, 2005 and 2011. Results: There were significant differences in pre-fire treated and untreated plant communities by species composition and abundance in 2004 and 2005, but these communities were beginning to converge in 2011. Total understorey plant cover was significantly higher in untreated areas for all 3 yr. Plant cover generally increased between 2004 and 2005 and markedly decreased in 2011, with the exception of shrub cover, which steadily increased through time. The sharp decrease in forb and graminoid cover in 2011 is likely related to drought conditions since the fire. Annual/biennial forb and graminoid cover decreased relative to perennial cover through time, consistent with the initial floristics hypothesis. Exotic plant response was highly variable and not limited to the immediate post-fire, annual/biennial community. Despite low overall exotic forb and graminoid cover for all years (<2.5%), several exotic species increased in frequency, and the relative proportion of exotic to native cover increased through time. Conclusions: Pre-treatment fuel reduction treatments helped maintain foundation overstorey species and associated native plant communities following this large wildfire. The overall low cover of exotic species on these sites supports other findings that the disturbance associated with high-severity fire does not always result in exotic species invasions. The increase in relative cover and frequency though time indicates that some species are proliferating, and continued monitoring is recommended. Patterns of exotic species invasions after severe burning are not easily predicted, and are likely more dependent on site-specific factors such as propagules, weather patterns and management.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Case studies of the expansion of Acacia dealbata in the valley of the river Mino (Galicia, Spain)
Abstract: Aim of study: Acacia dealbata is a naturalized tree of invasive behaviour that has expanded from small plots associated with vineyards into forest ecosystems. Our main objective is to find evidence to support the notion that disturbances, particularly forest fires, are important driving factors in the current expansion of A. dealbata. Area of study: We mapped it current distribution using three study areas and assesses the temporal changes registered in forest cover in these areas of the valley of the river Mino. Material and Methods: The analyses were based on visual interpretation of aerial photographs taken in 1985 and 2003 of three 1x1 km study areas and field works. Main result: A 62.4%, 48.6% and 22.2% of the surface area was covered by A. dealbata in 2003 in pure or mixed stands. Furthermore, areas composed exclusively of A. dealbata make up 33.8%, 15.2% and 5.7% of the stands. The transition matrix analyses between the two dates support our hypothesis that the areas currently covered by A. dealbata make up a greater proportion of the forest area previously classified as unwooded or open forest than those without A. dealbata cover. Both of these surface types are the result of an important impact of fire in the region. Within each area, A. dealbata is mainly located on steeper terrain, which is more affected by fires. Research highlights: A. dealbata is becoming the dominant tree species over large areas and the invasion of this species gives rise to monospecific stands, which may have important implications for future fire regimes. Keywords: Fire regime; Mimosa; plant invasion; silver wattle.
Extracted statement — Type of disturbance: Fire
Research field: Ecology and Evolutionary Biology
Title: Fish species introductions provide novel insights into the patterns and drivers of phylogenetic structure in freshwaters
Abstract: Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species.
Extracted statement — Investigated species: Fishes
Research field: Ecology and Evolutionary Biology
Title: Propagule pressure and the invasion risks of non-native freshwater fishes: a case study in England
Abstract: European countries in general, and England in particular, have a long history of introducing non-native fish species, but there exist no detailed studies of the introduction pathways and propagules pressure for any European country. Using the nine regions of England as a preliminary case study, the potential relationship between the occurrence in the wild of non-native freshwater fishes (from a recent audit of non-native species) and the intensity (i.e. propagule pressure) and diversity of fish imports was investigated. The main pathways of introduction were via imports of fishes for ornamental use (e.g. aquaria and garden ponds) and sport fishing, with no reported or suspected cases of ballast water or hull fouling introductions. The recorded occurrence of non-native fishes in the wild was found to be related to the time (number of years) since the decade of introduction. A shift in the establishment rate, however, was observed in the 1970s after which the ratio of established-to-introduced species declined. The number of established non-native fish species observed in the wild was found to increase significantly (P < 0·05) with increasing import intensity (log10x + 1 of the numbers of fish imported for the years 2000–2004) and with increasing consignment diversity (log10x + 1 of the numbers of consignment types imported for the years 2000–2004). The implications for policy and management are discussed.
Extracted statement — Investigated species: Fishes
Research field: Ecology and Evolutionary Biology
Title: The demography of introduction pathways, propagule pressure and occurrences of non-native freshwater fish in England
Abstract: 1. Biological invasion theory predicts that the introduction and establishment of non-native species is positively correlated with propagule pressure. Releases of pet and aquarium fishes to inland waters has a long history; however, few studies have examined the demographic basis of their importation and incidence in the wild. 2. For the 1500 grid squares (10×10 km) that make up England, data on human demographics (population density, numbers of pet shops, garden centres and fish farms), the numbers of non-native freshwater fishes (from consented licences) imported in those grid squares (i.e. propagule pressure), and the reported incidences (in a national database) of non-native fishes in the wild were used to examine spatial relationships between the occurrence of non-native fishes and the demographic factors associated with propagule pressure, as well as to test whether the demographic factors are statistically reliable predictors of the incidence of non-native fishes, and as such surrogate estimators of propagule pressure. 3. Principal coordinates of neighbour matrices analyses, used to generate spatially explicit models, and confirmatory factor analysis revealed that spatial distributions of non-native species in England were significantly related to human population density, garden centre density and fish farm density. Human population density and the number of fish imports were identified as the best predictors of propagule pressure. 4. Human population density is an effective surrogate estimator of non-native fish propagule pressure and can be used to predict likely areas of non-native fish introductions. In conjunction with fish movements, where available, human population densities can be used to support biological invasion monitoring programmes across Europe (and perhaps globally) and to inform management decisions as regards the prioritization of areas for the control of non-native fish introductions. © Crown copyright 2010. Reproduced with the permission of her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Extracted statement — Investigated species: Fishes
Research field: Ecology and Evolutionary Biology
Title: Propagule pressure drives establishment of introduced freshwater fish: quantitative evidence from an irrigation network
Abstract: Propagule pressure is recognized as a fundamental driver of freshwater fish invasions, though few studies have quantified its role. Natural experiments can be used to quantify the role of this factor relative to others in driving establishment success. An irrigation network in South Africa takes water from an inter-basin water transfer (IBWT) scheme to supply multiple small irrigation ponds. We compared fish community composition upstream, within, and downstream of the irrigation network, to show that this system is a unidirectional dispersal network with a single immigration source. We then assessed the effect of propagule pressure and biological adaptation on the colonization success of nine fish species across 30 recipient ponds of varying age. Establishing species received significantly more propagules at the source than did incidental species, while rates of establishment across the ponds displayed a saturation response to propagule pressure. This shows that propagule pressure is a significant driver of establishment overall. Those species that did not establish were either extremely rare at the immigration source or lacked the reproductive adaptations to breed in the ponds. The ability of all nine species to arrive at some of the ponds illustrates how long-term continuous propagule pressure from IBWT infrastructure enables range expansion of fishes. The quantitative link between propagule pressure and success and rate of population establishment confirms the driving role of this factor in fish invasion ecology.
Extracted statement — Investigated species: Fishes