Moussab/ORKG-training-evaluation-set huggingface dataset:
Research field: Ecology and Evolutionary Biology
Title: A comparison of the urban flora of different phytoclimatic regions in Italy
Abstract: This study is a comparison of the spontaneous vascular flora of five Italian cities: Milan, Ancona, Rome, Cagliari and Palermo. The aims of the study are to test the hypothesis that urbanization results in uniformity of urban floras, and to evaluate the role of alien species in the flora of settlements located in different phytoclimatic regions. To obtain comparable data, ten plots of 1 ha, each representing typical urban habitats, were analysed in each city. The results indicate a low floristic similarity between the cities, while the strongest similarity appears within each city and between each city and the seminatural vegetation of the surrounding region. In the Mediterranean settlements, even the most urbanized plots reflect the characters of the surrounding landscape and are rich in native species, while aliens are relatively few. These results differ from the reported uniformity and the high proportion of aliens which generally characterize urban floras elsewhere. To explain this trend the importance of apophytes (indigenous plants expanding into man-made habitats) is highlighted; several Mediterranean species adapted to disturbance (i.e. grazing, trampling, and human activities) are pre-adapted to the urban environment. In addition, consideration is given to the minor role played by the ‘urban heat island’ in the Mediterranean basin, and to the structure and history of several Italian settlements, where ancient walls, ruins and archaeological sites in the periphery as well as in the historical centres act as conservative habitats and provide connection with seed-sources on the outskirts.
Extracted statement — Investigated species: Plants
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 — Investigated species: Plants
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 — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Plant and Small Vertebrate Composition and Diversity 36-39 Years After Root Plowing
Abstract: Abstract Root plowing is a common management practice to reduce woody vegetation and increase herbaceous forage for livestock on rangelands. Our objective was to test the hypotheses that four decades after sites are root plowed they have 1) lower plant species diversity, less heterogeneity, greater percent canopy cover of exotic grasses; and 2) lower abundance and diversity of amphibians, reptiles, and small mammals, compared to sites that were not disturbed by root plowing. Pairs of 4-ha sites were selected for sampling: in each pair of sites, one was root plowed in 1965 and another was not disturbed by root plowing (untreated). We estimated canopy cover of woody and herbaceous vegetation during summer 2003 and canopy cover of herbaceous vegetation during spring 2004. We trapped small mammals and herpetofauna in pitfall traps during late spring and summer 2001–2004. Species diversity and richness of woody plants were less on root-plowed than on untreated sites; however, herbaceous plant and animal species did not differ greatly between treatments. Evenness of woody vegetation was less on root-plowed sites, in part because woody legumes were more abundant. Abundance of small mammals and herpetofauna varied with annual rainfall more than it varied with root plowing. Although structural differences existed between vegetation communities, secondary succession of vegetation reestablishing after root plowing appears to be leading to convergence in plant and small animal species composition with untreated sites.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Roads as conduits for exotic plant invasions in a semiarid landscape
Abstract: Abstract: Roads are believed to be a major contributing factor to the ongoing spread of exotic plants. We examined the effect of road improvement and environmental variables on exotic and native plant diversity in roadside verges and adjacent semiarid grassland, shrubland, and woodland communities of southern Utah ( U.S.A. ). We measured the cover of exotic and native species in roadside verges and both the richness and cover of exotic and native species in adjacent interior communities ( 50 m beyond the edge of the road cut ) along 42 roads stratified by level of road improvement ( paved, improved surface, graded, and four‐wheel‐drive track ). In roadside verges along paved roads, the cover of Bromus tectorum was three times as great ( 27% ) as in verges along four‐wheel‐drive tracks ( 9% ). The cover of five common exotic forb species tended to be lower in verges along four‐wheel‐drive tracks than in verges along more improved roads. The richness and cover of exotic species were both more than 50% greater, and the richness of native species was 30% lower, at interior sites adjacent to paved roads than at those adjacent to four‐wheel‐drive tracks. In addition, environmental variables relating to dominant vegetation, disturbance, and topography were significantly correlated with exotic and native species richness and cover. Improved roads can act as conduits for the invasion of adjacent ecosystems by converting natural habitats to those highly vulnerable to invasion. However, variation in dominant vegetation, soil moisture, nutrient levels, soil depth, disturbance, and topography may render interior communities differentially susceptible to invasions originating from roadside verges. Plant communities that are both physically invasible ( e.g., characterized by deep or fertile soils ) and disturbed appear most vulnerable. Decision‐makers considering whether to build, improve, and maintain roads should take into account the potential spread of exotic plants.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Testing life history correlates of invasiveness using congeneric plant species
Abstract: We used three congeneric annual thistles, which vary in their ability to invade California (USA) annual grasslands, to test whether invasiveness is related to differences in life history traits. We hypothesized that populations of these summer-flowering Centaurea species must pass through a demographic gauntlet of survival and reproduction in order to persist and that the most invasive species (C. solstitialis) might possess unique life history characteristics. Using the idea of a demographic gauntlet as a conceptual framework, we compared each congener in terms of (1) seed germination and seedling establishment, (2) survival of rosettes subjected to competition from annual grasses, (3) subsequent growth and flowering in adult plants, and (4) variation in breeding system. Grazing and soil disturbance is thought to affect Centaurea establishment, growth, and reproduction, so we also explored differences among congeners in their response to clipping and to different sizes of soil disturbance. We found minimal differences among congeners in either seed germination responses or seedling establishment and survival. In contrast, differential growth responses of congeners to different sizes of canopy gaps led to large differences in adult size and fecundity. Canopy-gap size and clipping affected the fecundity of each species, but the most invasive species (C. solstitialis) was unique in its strong positive response to combinations of clipping and canopy gaps. In addition, the phenology of C. solstitialis allows this species to extend its growing season into the summer—a time when competition from winter annual vegetation for soil water is minimal. Surprisingly, C. solstitialis was highly self-incompatible while the less invasive species were highly self-compatible. Our results suggest that the invasiveness of C. solstitialis arises, in part, from its combined ability to persist in competition with annual grasses and its plastic growth and reproductive responses to open, disturbed habitat patches. Corresponding Editor: D. P. C. Peters.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Invasibility and abiotic gradients: the positive correlation between native and exotic plant diversity
Abstract: We sampled the understory community in an old-growth, temperate forest to test alternative hypotheses explaining the establishment of exotic plants. We quantified the individual and net importance of distance from areas of human disturbance, native plant diversity, and environmental gradients in determining exotic plant establishment. Distance from disturbed areas, both within and around the reserve, was not correlated to exotic species richness. Numbers of native and exotic species were positively correlated at large (50 m 2 ) and small (10 m 2 ) plot sizes, a trend that persisted when relationships to environ- mental gradients were controlled statistically. Both native and exotic species richness in- creased with soil pH and decreased along a gradient of increasing nitrate availability. Exotic species were restricted to the upper portion of the pH gradient and had individualistic responses to the availability of soil resources. These results are inconsistent with both the diversity-resistance and resource-enrichment hypotheses for invasibility. Environmental conditions favoring native species richness also favor exotic species richness, and com- petitive interactions with the native flora do not appear to limit the entry of additional species into the understory community at this site. It appears that exotic species with niche requirements poorly represented in the regional flora of native species may establish with relatively little resistance or consequence for native species richness.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Fire and competition in a southern California grassland: impacts on the rare forb Erodium macrophyllum
Abstract: Summary 1. The use of off-season burns to control exotic vegetation shows promise for land managers. In California, wildfires tend to occur in the summer and autumn, when most grassland vegetation is dormant. The effects of spring fires on native bunchgrasses have been examined but their impacts on native forbs have received less attention. 2. We introduced Erodium macrophyllum, a rare native annual forb, by seeding plots in 10 different areas in a California grassland. We tested the hypotheses that E. macrophyllum would perform better (increased fecundity and germination) when competing with native grasses than with a mixture of exotic and native grasses, and fire would alter subsequent demography of E. macrophyllum and other species’ abundances. We monitored the demography of E. macrophyllum for two seasons in plots manually weeded so that they were free from exotics, and in areas that were burned or not burned the spring after seeding. 3. Weeding increased E. macrophyllum seedling emergence, survival and fecundity during both seasons. When vegetation was burned in June 2001 (at the end of the first growing season) to kill exotic grass seeds before they dispersed, all E. macrophyllum plants had finished their life cycle and dispersed seeds, suggesting that burns at this time of year would not directly impact on fecundity. In the growing season after burning (2002), burned plots had less recruitment of E. macrophyllum but more establishment of native grass seedlings, suggesting burning may differentially affect seedling recruitment. 4. At the end of the second growing season (June 2002), burned plots had less cover of exotic and native grasses but more cover of exotic forbs. Nevertheless, E. macrophyllum plants in burned plots had greater fecundity than in non-burned plots, suggesting that exotic grasses are more competitive than exotic forbs. 5. A glasshouse study showed that exotic grasses competitively suppress E. macrophyllum to a greater extent than native grasses, indicating that the poor performance of E. macrophyllum in the non-burned plots was due to exotic grass competition. 6. Synthesis and applications. This study illustrates that fire can alter the competitive environment in grasslands with differential effects on rare forbs, and that exotic grasses strongly interfere with E. macrophyllum. For land managers, the benefits of prescribed spring burns will probably outweigh the costs of decreased E. macrophyllum establishment. Land managers can use spring burns to cause a flush of native grass recruitment and to create an environment that is, although abundant with exotic forbs, ultimately less competitive compared with non-burned areas dominated by exotic grasses.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Influence of fire and soil nutrients on native and non-native annuals at remnant vegetation edges in the Western Australian wheatbelt
Abstract: . The effect of fire on annual plants was examined in two vegetation types at remnant vegetation edges in the Western Australian wheatbelt. Density and cover of non-native species were consistently greatest at the reserve edges, decreasing rapidly with increasing distance from reserve edge. Numbers of native species showed little effect of distance from reserve edge. Fire had no apparent effect on abundance of non-natives in Allocasuarina shrubland but abundance of native plants increased. Density of both non-native and native plants in Acacia acuminata-Eucalyptus loxophleba woodland decreased after fire. Fewer non-native species were found in the shrubland than in the woodland in both unburnt and burnt areas, this difference being smallest between burnt areas. Levels of soil phosphorus and nitrate were higher in burnt areas of both communities and ammonium also increased in the shrubland. Levels of soil phosphorus and nitrate were higher at the reserve edge in the unburnt shrubland, but not in the woodland. There was a strong correlation between soil phosphorus levels and abundance of non-native species in the unburnt shrubland, but not after fire or in the woodland. Removal of non-native plants in the burnt shrubland had a strong positive effect on total abundance of native plants, apparently due to increases in growth of smaller, suppressed native plants in response to decreased competition. Two native species showed increased seed production in plots where non-native plants had been removed. There was a general indication that, in the short term, fire does not necessarily increase invasion of these communities by non-native species and could, therefore be a useful management tool in remnant vegetation, providing other disturbances are minimised.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Disturbance Facilitates Invasion: The Effects Are Stronger Abroad than at Home
Abstract: Disturbance is one of the most important factors promoting exotic invasion. However, if disturbance per se is sufficient to explain exotic success, then “invasion” abroad should not differ from “colonization” at home. Comparisons of the effects of disturbance on organisms in their native and introduced ranges are crucial to elucidate whether this is the case; however, such comparisons have not been conducted. We investigated the effects of disturbance on the success of Eurasian native Centaurea solstitialis in two invaded regions, California and Argentina, and one native region, Turkey, by conducting field experiments consisting of simulating different disturbances and adding locally collected C. solstitialis seeds. We also tested differences among C. solstitialis genotypes in these three regions and the effects of local soil microbes on C. solstitialis performance in greenhouse experiments. Disturbance increased C. solstitialis abundance and performance far more in nonnative ranges than in the native range, but C. solstitialis biomass and fecundity were similar among populations from all regions grown under common conditions. Eurasian soil microbes suppressed growth of C. solstitialis plants, while Californian and Argentinean soil biota did not. We suggest that escape from soil pathogens may contribute to the disproportionately powerful effect of disturbance in introduced regions.
Extracted statement — Investigated species: Plants
Research field: Ecology and Evolutionary Biology
Title: Removal of nonnative vines and post-hurricane recruitment in tropical hardwood forests of Florida
Abstract: Abstract In hardwood subtropical forests of southern Florida, nonnative vines have been hypothesized to be detrimental, as many species form dense “vine blankets” that shroud the forest. To investigate the effects of nonnative vines in post-hurricane regeneration, we set up four large (two pairs of 30 × 60 m) study areas in each of three study sites. One of each pair was unmanaged and the other was managed by removal of nonnative plants, predominantly vines. Within these areas, we sampled vegetation in 5 × 5 m plots for stems 2 cm DBH (diameter at breast height) or greater and in 2 × 0.5 m plots for stems of all sizes. For five years, at annual censuses, we tagged and measured stems of vines, trees, shrubs and herbs in these plots. For each 5 × 5 m plot, we estimated percent coverage by individual vine species, using native and nonnative vines as classes. We investigated the hypotheses that: (1) plot coverage, occurrence and recruitment of nonnative vines were greater than that of native vines in unmanaged plots; (2) the management program was effective at reducing cover by nonnative vines; and (3) reduction of cover by nonnative vines improved recruitment of seedlings and saplings of native trees, shrubs, and herbs. In unmanaged plots, nonnative vines recruited more seedlings and had a significantly higher plot-cover index, but not a higher frequency of occurrence. Management significantly reduced cover by nonnative vines and had a significant overall positive effect on recruitment of seedlings and saplings of native trees, shrubs and herbs. Management also affected the seedling community (which included vines, trees, shrubs, and herbs) in some unanticipated ways, favoring early successional species for a longer period of time. The vine species with the greatest potential to “strangle” gaps were those that rapidly formed dense cover, had shade tolerant seedling recruitment, and were animal-dispersed. This suite of traits was more common in the nonnative vines than in the native vines. Our results suggest that some vines may alter the spatiotemporal pattern of recruitment sites in a forest ecosystem following a natural disturbance by creating many very shady spots very quickly.
Extracted statement — Investigated species: Plants