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1.
In the southern hemisphere, the airborne prevalence and seasonal distribution of Asteraceae pollen are poorly characterized. In this study, we assessed the longitudinal distribution of Asteraceae pollen using an historic aerobiological dataset. The influence of weather parameters on pollen derived from Asteraceae species was additionally explored. Asteraceae pollen was collected using a static Burkard 7-day spore trap during a 5-year (June 1994–May 1999) aerometric surveillance program in Brisbane, Australia. Two discrete seasonal intervals were identified each sampling year. The first interval (September and October) consisted of small quantities of unidentifiable Asteraceae pollen. The second interval (March and April) was characterized by the highest concentrations of Asteraceae pollen that were predominantly derived from Baccharis halimifolia. Associations between daily Asteraceae pollen concentrations and temperature were observed during each sampling year. The results of the study demonstrated that pollen derived from B. halimifolia, an invasive weed species introduced in the late nineteenth century, continue to be in the environment of Brisbane. Given the public health burden associated with personal Asteraceae pollen exposure in other geographic locations, future Australian-based clinical studies should characterize the contribution of Asteraceae pollen, in particular B. halimifolia, to allergic sensitization and respiratory morbidity.  相似文献   

2.
  • 1 Insect pests, biological invasions and climate change are considered to represent major threats to biodiversity, ecosystem functioning, agriculture and forestry. Deriving hypothesis of contemporary and/or future potential distributions of insect pests and invasive species is becoming an important tool for predicting the spatial structure of potential threats.
  • 2 The western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte is a pest of maize in North America that has invaded Europe in recent years, resulting in economic costs in terms of maize yields in both continents. The present study aimed to estimate the dynamics of potential areas of invasion by the WCR under a climate change scenario in the Northern Hemisphere. The areas at risk under this scenario were assessed by comparing, using complementary approaches, the spatial projections of current and future areas of climatic favourability of the WCR. Spatial hypothesis were generated with respect to the presence records in the native range of the WCR and physiological thresholds from previous empirical studies.
  • 3 We used a previously developed protocol specifically designed to estimate the climatic favourability of the WCR. We selected the most biologically relevant climatic predictors and then used multidimensional envelope (MDE) and Mahalanobis distances (MD) approaches to derive potential distributions for current and future climatic conditions.
  • 4 The results obtained showed a northward advancement of the upper physiological limit as a result of climate change, which might increase the strength of outbreaks at higher latitudes. In addition, both MDE and MD outputs predict the stability of climatic favourability for the WCR in the core of the already invaded area in Europe, which suggests that this zone would continue to experience damage from this pest in Europe.
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3.
Environmental conditions may influence the presence and strength of competitive interactions between different life forms, thereby shaping community composition and structure, and corresponding fuel dynamics. Woodland and shrubland communities of the Mediterranean climate region of South Eastern Australia contain a varied mixture of herbaceous and woody plants. The ratio of herbaceous to woody plants changes along gradients of temperature, moisture and soil fertility. This study aimed to experimentally examine the relative importance of, and interactions between environmental controls (moisture and soil fertility) on the balance of dominant herbaceous (Triodia scariosa) and woody plants (e.g. Acacia ligulata and Leptospermum coriaceum) and their ultimate effects on fuel and fire regimes. The results suggest that environmental determinants of the growth of T. scariosa are likely to be more important than interactions with shrubs in controlling the distribution of T. scariosa. The growth of T. scariosa was consistently higher under hot temperatures and on the less fertile yellow sands, which dominate the south of the region. The results suggest that there is strong potential for the distribution and abundance of T. scariosa to be altered in the future with changes in temperature associated with climate change. The distribution of soil types across the Mediterranean climate region of South Eastern Australia may be predisposed to favour the southerly expansion of T. scariosa‐dominated communities in the future under a warmer climate.  相似文献   

4.
  • 1 Invertebrate pests, such as blue oat mites Penthaleus spp., cause significant economic damage to agricultural crops in Australia. Climate is a major driver of invertebrate species distributions and climate change is expected to shift pest assemblages and pest prevalence across Australia. At this stage, little is known of how individual species will respond to climate change.
  • 2 We have mapped the current distribution for each of the three pest Penthaleus spp. in Australia and built ecological niche models for each species using the correlative modelling software, maxent . Predictor variables useful for describing the climate space of each species were determined and the models were projected into a range of future climate change scenarios to assess how climate change may alter species‐specific distribution patterns in Australia.
  • 3 The distributions of the three cryptic Penthaleus spp. are best described with different sets of climatic variables. Suitable climate space for all species decreases under the climate change scenarios investigated in the present study. The models also indicate that the assemblage of Penthaleus spp. is likely to change across Australia, particularly in Western Australia, South Australia and Victoria.
  • 4 These results show the distributions of the three Penthaleus spp. are correlated with different climatic variables, and that regional control of mite pests is likely to change in the future. A further understanding of ecological and physiological processes that may influence the distribution and pest status of mites is required.
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5.
The impacts of climate change in the potential distribution and relative abundance of a C3 shrubby vine, Cryptostegia grandiflora, were investigated using the CLIMEX modelling package. Based upon its current naturalised distribution, C. grandiflora appears to occupy only a small fraction of its potential distribution in Australia under current climatic conditions; mostly in apparently sub-optimal habitat. The potential distribution of C. grandiflora is sensitive towards changes in climate and atmospheric chemistry in the expected range of this century, particularly those that result in increased temperature and water use efficiency. Climate change is likely to increase the potential distribution and abundance of the plant, further increasing the area at risk of invasion, and threatening the viability of current control strategies markedly. By identifying areas at risk of invasion, and vulnerabilities of control strategies, this analysis demonstrates the utility of climate models for providing information suitable to help formulate large-scale, long-term strategic plans for controlling biotic invasions. The effects of climate change upon the potential distribution of C. grandiflora are sufficiently great that strategic control plans for biotic invasions should routinely include their consideration. Whilst the effect of climate change upon the efficacy of introduced biological control agents remain unknown, their possible effect in the potential distribution of C. grandiflora will likely depend not only upon their effects on the population dynamics of C. grandiflora, but also on the gradient of climatic suitability adjacent to each segment of the range boundary.  相似文献   

6.
Wildfire is a major driver of spatio‐temporal variation in terrestrial ecosystems. Large wildfires are predicted to occur more frequently due to climate change. The mechanisms by which post‐fire recovery proceeds are influenced by the abundance of survivors, and their distribution in relation to habitat variability and refugia. Thus, characterising early post‐fire demographic processes is critical to understanding the demographic and community‐level responses of ecosystems to fire. The Black Saturday fires of February 2009 burnt an area of approximately 3500 km2 in Victoria, Australia. We quantified the effects of this high severity forest fire on the habitat, abundance, sex ratio and body mass of two small mammal species, the agile antechinus Antechinus agilis and bush rat Rattus fuscipes. We developed a hypothetical framework to distinguish in situ survival and rapid recolonisation as the processes underlying short‐term post‐fire distributions. These hypotheses were based on expected patterns of abundance over increasing distances from unburnt sources, and the estimated recolonisation capabilities of each species and sex. The agile antechinus and bush rat were present in burnt sites at 30% and 12% of the density observed in unburnt sites. In situ survival, and not recolonisation, was the most plausible explanation for our findings. Abundance and body mass data indicated a greater effect of fire on the bush rat than the agile antechinus. The bush rat showed a shift in topographic association, whereby drainage lines acted as post‐fire refugia. Our findings suggest these species do not depend on recolonisation for recovery, and that the bush rat will follow a nucleated recovery, expanding from topographic refugia. Thus, connectivity‐reducing management activities, such as salvage logging and firebreak and road construction, may not affect the early stages of population recovery in remaining stands of burnt forest. Rather, ongoing recovery is likely to be limited by demographic rates and resource availability.  相似文献   

7.
The nocturnal foliage feeding ChrysomelidLioplacis elliptica Stal occurs onBaccharis gaudichaudiana DC. in Brazil. Studies of its biology and host plant specificity showed it was restricted tobaccharis spp. It was introduced into Australia for the control ofB. halimifolia L. in 1976 and first released in 1977. Field colonies persisted for up to 3 years after which no further evidence of survival was found.   相似文献   

8.
Parapatry is a biogeographical term used to refer to organisms whose ranges do not overlap, but are immediately adjacent to each other; they only co‐occur – if at all – in a narrow contact zone. Often there are no environmental barriers in the contact zones, hence competitive interaction is usually advocated as the factor that modulates species distribution ranges. Even though the effects of climate change on species distribution have been widely studied, few studies have explored these effects on the biogeographical relationships between closely related, parapatric, species. We modelled environmental favourability for three parapatric hare species in Europe – Lepus granatensis, L. europaeus and L. timidus – using ecogeographical variables and projected the models into the future according to the IPCC A2 emissions scenario. Favourabilities for present and future scenarios were combined using fuzzy logic with the following aims: (i) to determine the biogeographical relationships between hare species in parapatry, that is L. granatensis/L. europaeus and L. europaeus/L. timidus and (ii) to assess the effects of climate change on each species as well as on their interspecific interactions. In their contact area L. granatensis achieved higher favourability values than L. europaeus, suggesting that if both species have a similar population status, the former species may have some advantages over the latter if competitive relationships are established. Climate change had the most striking effect on the distribution of L. timidus, especially when interspecific interactions with L. europaeus were taken into account, which may compromise the co‐existence of L. timidus. The results of this study are relevant not only for understanding the distribution patterns of the hares studied and the effects of climate change on these patterns, but also for improving the general application of species distribution models to the prediction of the effects of climate change on biodiversity.  相似文献   

9.
Atlantic subhalophilous communities are habitats of high conservation value that are seriously threatened by plant invasions. The dioecious alien shrub Baccharis halimifolia L. (Asteraceae) is among the most aggressive invaders in estuarine communities in Europe, especially in sea rush communities of Juncus maritimus. We investigated the growth and flowering phenology of B. halimifolia through fine-scale environmental gradients, and we assessed the intersexual differentiated responses. We monitored 120 individuals of B. halimifolia growing in rush communities differing in salinity and waterlogging through one growing season in Urdaibai Biosphere Reserve. Ground water salinity and water table level were also recorded. Overall, B. halimifolia shoot growth occurred from May to December and flowering in late August, but males flowered earlier than females. However, we found high intrapopulation and intersexual variation in the phenology of B. halimifolia, related to fine-scale variations in edaphic conditions. Growth rate and leaf production were lower in high-salinity rush communities. Females and males showed different phenological responses to environmental conditions. Females appeared to be more sensitive to salinity than males, but males experienced higher levels of attack by natural enemies. The implications for the invasiveness and management of sea rush communities are discussed.  相似文献   

10.
Climate change and invasive species pose important conservation issues separately, and should be examined together. We used existing long term climate datasets for the US to project potential climate change into the future at a finer spatial and temporal resolution than the climate change scenarios generally available. These fine scale projections, along with new species distribution modeling techniques to forecast the potential extent of invasive species, can provide useful information to aide conservation and invasive species management efforts. We created habitat suitability maps for Pueraria montana (kudzu) under current climatic conditions and potential average conditions up to 30 years in the future. We examined how the potential distribution of this species will be affected by changing climate, and the management implications associated with these changes. Our models indicated that P. montana may increase its distribution particularly in the Northeast with climate change and may decrease in other areas.  相似文献   

11.
Perhaps one of the central questions in ecology has been what limits the geographic distribution of species. The geographic distributions of the reptile-ticks Amblyomma limbatum, Bothriocroton hydrosauri and Amblyomma albolimbatum are a classic example of this problem: where these ticks meet, narrow regions-of-overlap often occur. Despite studies of interactions among these ticks, and of these ticks and their environment, we still do not understand what limits their geographic distributions. Many hypotheses have been proposed and tested, but all have seemingly been rejected. Our aim was to account for the abundance and the geographic distributions of A. limbatum and B. hydrosauri at Bundey Bore Station, South Australia, where these species come in contact and have been studied for over 35 years, leading to over 55 000 records of reptiles and their ticks using a capture-mark-recapture approach. We constructed models which had combinations of temperature and moisture indices from different months of the year to determine the relationship between climate and tick abundance, and between climate and the shifting local geographic distribution of A. limbatum and B. hydrosauri at Bundey Bore Station. We found that climate together with the abundance of ticks in the previous year and the abundance of the lizard host, accounted for 54%–77% of the variation in the abundance of A. limbatum and B. hydrosauri among years. We also found that the climate in late autumn to winter, together with the abundance of ticks and their host, accounted for 18%–84% of the variation in the geographic distributions of these ticks among years. Climate was central to the abundance and the geographic distributions of A. limbatum and B. hydrosauri at Bundey Bore Station. We speculate that the same mechanisms account for the geographic distributions of A. limbatum, B. hydrosauri and A. albolimbatum elsewhere in Australia; so, climate may explain the three-tick problem in Austral ecology.  相似文献   

12.
Mimosa pigra L. is one of the most troublesome weeds in northern Australia, and is the target of a large biological control program, with 14 agents released to date. This paper describes surveys conducted between 1997 and 2004, for eight of these biological control agents. Surveys assessed the establishment of key agents. Both distribution and abundance of the most damaging agent, the stem-borer Carmenta mimosa Eichlin and Passoa (Lep.: Sesiidae), increased during the eight year period and the moth is now present in all catchments with major M. pigra infestations. The tip-borer, Neurostrota gunniella Busck (Lep.: Gracillariidae) is present in all M. pigra infestations, attacking 94% of tips. The leaf and flower-feeder, Coelocephalapion pigrae Kissinger (Col., Curculionidae) is widespread and its abundance is stable. Neither Acanthoscelides puniceus Johnson (Col., Bruchidae) nor Chlamisus mimosae Karren (Col., Chrysomelidae) were widespread or abundant when surveys commenced and populations declined during the survey period. The nocturnal beetle Malacorhinus irregularis Jacoby (Col., Chrysomelidae) was not found during these surveys, but later searches using different methods found it at three sites. Six other agents appeared not to have established, or are present at densities too low to be detected. How the results of these surveys affect management of M. pigra, and projections for future impacts against this weed are discussed. Using survey results and published literature we concluded that (1) seed and flower feeders must be capable of surviving periods of low food availability; (2) some climate matching may be beneficial before fungal biocontrol agents are released and (3) even in well studied systems such as M. pigra, the failure of an agent to establish cannot always be explained.  相似文献   

13.
Control programs are implemented to mitigate the damage caused by invasive species worldwide. In the highly invaded Great Lakes, the climate is expected to become warmer with more extreme weather and variable precipitation, resulting in shorter iced‐over periods and variable tributary flows as well as changes to pH and river hydrology and hydrogeomorphology. We review how climate change influences physiology, behavior, and demography of a damaging invasive species, sea lamprey (Petromyzon marinus), in the Great Lakes, and the consequences for sea lamprey control efforts. Sea lamprey control relies on surveys to monitor abundance of larval sea lamprey in Great Lakes tributaries. The abundance of parasitic, juvenile sea lampreys in the lakes is calculated by surveying wounding rates on lake trout (Salvelinus namaycush), and trap surveys are used to enumerate adult spawning runs. Chemical control using lampricides (i.e., lamprey pesticides) to target larval sea lamprey and barriers to prevent adult lamprey from reaching spawning grounds are the most important tools used for sea lamprey population control. We describe how climate change could affect larval survival in rivers, growth and maturation in lakes, phenology and the spawning migration as adults return to rivers, and the overall abundance and distribution of sea lamprey in the Great Lakes. Our review suggests that Great Lakes sea lamprey may benefit from climate change with longer growing seasons, more rapid growth, and greater access to spawning habitat, but uncertainties remain about the future availability and suitability of larval habitats. Consideration of the biology of invasive species and adaptation of the timing, intensity, and frequency of control efforts is critical to the management of biological invasions in a changing world, such as sea lamprey in the Great Lakes.  相似文献   

14.
Bitou bush (Chrysanthemoides monilifera ssp. rotundata; Asteraceae) is a major woody weed that competes with the native legume Acacia sophorae in coastal ecosystems of eastern Australia. Three glasshouse experiments examined whether litter or soil from beneath bitou bush or Acacia plants could influence seed germination and seedling growth of A. sophorae. The presence of litter decreased seed germinability and this effect was greater for bitou bush litter than for Acacia litter. Shoot growth was increased by the addition of Rhizobium after 40 days, irrespective of soil type. After 78 days, shoot and root biomass were significantly lower for seedlings grown in bitou bush soil than for those grown in Acacia soil. There was a non‐significant trend towards a lower median population of Rhizobium in the soil beneath bitou bush than in that beneath Acacia. The results demonstrated a slight effect of bitou bush on the growth of A. sophorae, which could, however, be overshadowed by the judicious use of herbicides or fire for weed control and revegetation.  相似文献   

15.
The safety of biological control is a contentious issue. We suggest that constructing and analyzing food webs may be a valuable addition to standard biological control research techniques, as they offer a means of assessing the post-release safety of control agents. Using preliminary data to demonstrate the value of food webs in biocontrol programs, we quantified the extent to which a key agent has infiltrated natural communities in Australia and, potentially, impacted on non-target species. Using these data, we also demonstrate how food webs can be used to generate testable hypotheses regarding indirect interactions between introduced agents and non-target species. We developed food webs in communities invaded to varying degrees by an exotic weed, bitou bush, Chrysanthemoides monilifera ssp. rotundata, and a key biocontrol agent for this weed in Australia, the tephritid fly, Mesoclanis polana. Three food webs were constructed during springtime showing the interactions between plants, seed-feeding insects and their parasitoids. One food web was constructed in a plot of native Australian vegetation that was free of bitou bush (‘bitou-free’), another in a plot of Australian vegetation surrounded by an invasion of bitou bush (‘bitou-threatened’) and a third from a plot infested with a monoculture of bitou bush (‘bitou-infested’). The bitou-free web contained 36 species, the bitou-threatened plot 9 species and the bitou-infested web contained 6 species. One native Australian herbivore attacked the seeds of bitou bush. M. polana, a seed-feeding fly, was heavily attacked by native parasitoids, these being more abundant than the parasitoids feeding on the native seed feeders. A surprising result is that none of the three species of native parasitoids reared from M. polana were reared from any of the native herbivores. The food webs revealed how a highly host-specific biocontrol agent, such as M. polana has the potential to change community structure by increasing the abundance of native parasitoids. The webs also suggest that indirect interactions between M. polana and native non-target species are possible, these been mediated by shared parasitoids. The experiments necessary to determine the presence of these interactions are outlined.  相似文献   

16.
P. J. McFadyen 《BioControl》1987,32(4):329-331
Biology and host-specificity of the foliage-feeding chrysomelidMetallactus patagonicus Suffrian were studied in Brazil to determine its suitability for introduction into Australia to control the shrubBaccharis halimifolia L. Multiple-choice host preference testing of plants related toBaccharis and of desirable plants from a range of plant families, showed thatM. patagonicus was restricted toBaccharis spp. It was released in Australia in 1975, but did not establish.   相似文献   

17.
The ability of two plant-produced macrocyclic trichothecenes (baccharinoid B4 and roridin E) to induce callus growth of two trichothecene-producing Baccharis species (B. coridifolia and B. megapotamica) and two nontrichothecene-producing species (B. halimifolia and B. neglecta) was investigated. Roridin E had no effect in the induction of callus of B. coridifolia, a roridin-producing plant, but induced callus of nonroridin-producing plants (B. megapotamica, B. halimifolia, and B. neglecta). Baccharinoid B4 stimulated callus growth of B. megapotamica, a baccharinoid-producing plant, and inhibited growth of B. coridifolia, B. halimifolia, and B. neglecta callus tissues. The ability of roridin E to induce callus was most effective at concentrations of 10–8 and 10–6 M and when synergistically coupled with auxin, 2,4-dichlorophenoxyacetic acid (2,4-D). The ability of baccharinoid B4 to stimulate callus growth appeared to increase with increased concentration in the culture medium. Analysis of callus cultures grown in medium amended with roridin E showed that B4, roridin E, and 8-hydroxyroridin E and verrucarols were formed in the tissues but not in the medium. The results of this study indicated that while the callus-inducing ability of roridin E seemed to be nonspecies-specific in nature, the ability of B4 to stimulate callus was a highly species-specific phenomena. Callus-inducing activity of roridin E may depend on the capacity of plant species to transform exogenous roridin E into baccharinoids or other macrocyclic trichothecene derivatives.  相似文献   

18.
Towards an understanding of the Holocene distribution of Fagus sylvatica L.   总被引:1,自引:1,他引:1  
Aim Understanding the driving forces and mechanisms of changes in past plant distribution and abundance will help assess the biological consequences of future climate change scenarios. The aim of this paper is to investigate whether modelled patterns of climate parameters 6000 years ago can account for the European distribution of Fagus sylvatica at that time. Consideration is also given to the role of non‐climatic parameters as driving forces of the Holocene spread and population expansion of F. sylvatica. Location Europe. Methods European distributions were simulated using a physiologically‐based bioclimatic model (STASH) driven by three different atmospheric general circulation model (AGCM) outputs for 6000 years ago. Results The three simulations generally showed F. sylvatica to have potentially been as widespread 6000 years ago as it is today, which gives a profound mismatch with pollen‐based reconstructions of the F. sylvatica distribution at that time. The results indicate that drier conditions during the growing season 6000 years ago could have caused a restriction of the range in the south. Poorer growth conditions with consequently reduced competitive ability were modelled for large parts of France. Main conclusions Consideration of the entire European range of F. sylvatica showed that no single driving force could account for the observed distributional limits 6000 years ago, or the pattern of spread during the Holocene. Climatic factors, particularly drought during the growing season, are the likely major determinants of the potential range. Climatic factors are regionally moderated by competition, disturbance effects and the intrinsically slow rate of population increase of F. sylvatica. Dynamic vegetation modelling is needed to account for potentially important competitive interactions and their relationship with changing climate. We identify uncertainties in the climate and pollen data, as well as the bioclimatic model, which suggest that the current study does not identify whether or not climate determined the distribution of F. sylvatica 6000 years ago. Pollen data are better suited for comparison with relative abundance gradients rather than absolute distributional limits. These uncertainties from a study of the past, where we have information about plant distribution and abundance, argue for extreme caution in making forecasts for the future using equilibrium models.  相似文献   

19.
Summary Trirhabda bacharidis (Weber) (Chrysomelidae), a univoltine, monophagous beetle is the dominant herbivore on Baccharis halimifolia (Compositae), a woody, perennial shrub that leafs out in early spring and retains its leaves into November. Available plant biomass increases during the season but T. bacharidis feeds only during spring and early summer. During the remainder of the growing season, there are no major herbivores feeding on B. halimifolia. B. halimifolia leaves increase in toughness and thickness and decrease in moisture and nutrients as the season progresses. In feeding preference tests, T. bacharidis larvae preferred young leaves over leaves of older age classes. When reared on leaves of different ages, larvae fed on young leaves, weighed more, pupated earlier and had greater survivorship. T. bacharidis larvae showed no significant feeding preference for similarly tough B. halimifolia leaves painted with differing concentrations of late season acetone leaf extract. Elm leaves painted with the same leaf extracts were avoided by larvae of the non-adapted specialist Pyrrhalta luteola (Mueller) (Chrysomelidae).These results suggest that the adapted specialist, T. bacharidis, is not deterred by the B. halimifolia acetone soluble secondary chemical which increases in amount over the season. Decreasing leaf nitrogen (perhaps in concert with increasing leaf toughness) seems to be the primary factor that dissuades its feeding. However, acetone soluble secondary chemicals in the leaves of B. halimifolia may be effective in preventing herbivory from non-adapted insects.  相似文献   

20.
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