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Weather Events (weather + event)
Kinds of Weather Events Selected AbstractsInvasibility of grassland and heath communities exposed to extreme weather events , additive effects of diversity resistance and fluctuating physical environmentOIKOS, Issue 10 2008Juergen Kreyling Understanding the resistance of plant communities to invasion is urgent in times of changes in the physical environment due to climate change and changes in the resident communities due to biodiversity loss. Here, we test the interaction between repeated drought or heavy rainfall events and functional diversity of grassland and heath communities on invasibility, measured as the number of plant individuals invading from the matrix vegetation. Invasibility of experimental plant communities was influenced by extreme weather events, although no change in above-ground productivity of the resident communities was observed. Drought decreased invasibility while heavy rainfall increased invasibility, a pattern that is consistent with the fluctuating resource hypothesis. Higher community diversity generally decreased invasibility, which can be explained by a combination of the fluctuating resource hypothesis and niche theory. The effects of the physical environment (extreme weather events) and diversity resistance (community composition) were additive, as they were independent from each other. Differences in the composition of invading species sets were found, and Indicator Species Analysis revealed several invading species with significant affinity to one particular extreme weather event or community composition. This finding supports niche theory and contradicts neutral species assembly. Our data supports theories which predict decreased resistance of plant communities due to both increased climate variability and biodiversity loss. The effects of these two factors, however, appear to be independent from each other. [source] A high-resolution modelling case study of a severe weather event over New ZealandATMOSPHERIC SCIENCE LETTERS, Issue 3 2008Stuart Webster Abstract In this article, the ability of the Met Office Unified Model to simulate the severe weather over the South Island of New Zealand, on 8 January 2004 is investigated. Simulations were run at horizontal resolutions of between 60 and 1 km. The modelled broad-scale rainfall and wind features, most notably the area-averaged accumulated rainfall, were found to converge with resolution. At the highest resolutions, all the observed rainfall and wind features of this event were captured well by the model. Even the 12-km-resolution model is able to resolve the broad elongated ridge-like structure of the Southern Alps and qualitatively capture the main features of the rainfall and wind fields. Copyright © 2008 Royal Meteorological Society and Crown Copyright 2008, published by John Wiley & Sons, Ltd. [source] An application portal for collaborative coastal modelingCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2007Chongjie Zhang Abstract We describe the background, architecture and implementation of a user portal for the SCOOP coastal ocean observing and modeling community. SCOOP is engaged in the real-time prediction of severe weather events, including tropical storms and hurricanes, and provides operational information including wind, storm surge and resulting inundation, which are important for emergency management. The SCOOP portal, built with the GridSphere Framework, currently integrates customized Grid portlet components for data access, job submission, resource management and notification. Copyright © 2007 John Wiley & Sons, Ltd. [source] The mid-season crash in aphid populations: why and how does it occur?ECOLOGICAL ENTOMOLOGY, Issue 4 2004A. J. Karley Abstract., 1. Aphid populations on agricultural crops in temperature regions collapse over a few days from peak numbers to local extinction soon after mid-summer (e.g. mid-July in the U.K.). The populations recover 6,8 weeks later. There is anecdotal or incidental evidence of an equivalent mid-season population crash of aphids on grasses and forbs in natural vegetation. 2. The ecological factors causing the mid-season population crash of aphids include a decline in plant nutritional quality and increased natural enemy pressure as the season progresses. Extreme weather events, e.g. severe rainstorms, can precipitate the crash but weather conditions are not a consistent contributory factor. 3. The population processes underlying the crash comprise enhanced emigration, especially by alate (winged) aphids, depressed performance resulting in reduced birth rates, and elevated mortality caused by natural enemies. 4. Mathematical models, previously applied to aphid populations on agricultural crops, have great potential for studies of aphid dynamics in natural vegetation. In particular, they can help identify the contribution of various ecological factors to the timing of the population crash and offer explanations for how slow changes in population processes can result in a rapid collapse of aphid populations. [source] The importance of episodic weather events to the ecosystem of the Bering Sea shelfFISHERIES OCEANOGRAPHY, Issue 2 2005NICHOLAS A. BOND Abstract Climate variability on decadal time scales is generally recognized to influence high-latitude marine populations. Our recent work in studying air,sea interactions in the Bering Sea suggests that interannual to decadal climate variability is important through its modulation of the frequencies and magnitudes of weather events on intraseasonal time scales. We hypothesize that it is these weather events that directly impact the marine ecosystem of the Bering Sea shelf. The linkages between the event-scale weather and the ecosystem are illustrated with three examples: walleye pollock (Theragra chalcogramma), Tanner crabs (Chionoecetes bairdi), and coccolithophorid phytoplankton (Emiliania huxleyi). We hypothesize that the strong recruitment of walleye pollock that occurred in 1978, 1982, and 1996 can be attributed in part due to the seasonably strong storms that occurred in the early summer of those years. These storms caused greater than normal mixing of nutrients into the euphotic zone which presumably led to sustained primary productivity after the spring bloom and, possibly, enhanced prey concentrations for pollock larvae and their competitors. Recruitment of Tanner crab was particularly strong for the 1981 and 1984 year-classes. These years had periods of prominent east wind anomalies along the Alaska Peninsula during the previous winter. Such winds promote flow through Unimak Pass, and hence an enhanced flux of nutrient-rich water onto the shelf. This mechanism may have ultimately resulted in favorable feeding conditions for Tanner crab larvae. Finally, an unprecedented coccolithophorid bloom occurred over the Bering Sea shelf in the summer of 1997. This summer featured lighter winds and greater insolation than usual after a spring that included a very strong May storm. This combination brought about a warm, nutrient-poor upper mixed layer by mid-summer. This provided a competitive advantage for coccolithophorid phytoplankton in 1997 and to a lesser extent in 1998. Unusually high concentrations of coccolithophores persisted for the following two years although physical environmental conditions did not remain favorable. While slow variations in the overall aspects of the physical environment may be important for setting the stage, we propose that the significant multi-year adjustments in the marine ecosystem of the Bering Sea shelf are more directly caused by major air,sea interaction events on intraseasonal time scales. [source] Linking behavior, life history and food supply with the population dynamics of white-footed mice (Peromyscus leucopus)INTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 3 2007Stephen H. VESSEY Abstract In this paper we review and integrate key aspects of behavioral and life history traits, food supply and population dynamics of the white-footed mouse (Peromyscus leucopus), a species that is abundant and widely distributed across much of eastern North America. Results are based largely on a 33-year mark-and-recapture study in a forest fragment in northwest Ohio, USA. Behavioral plasticity in such reproductive traits as mating system and parental care allows this species to adjust quickly to changing environments. The species has a relatively "fast" life history, with rapid attainment of sexual maturity and high fecundity in the face of high mortality rates. Maximal reproductive effort early in life enables a rapid population response. Food supply, in the form of mast, determines the size of the reproducing population in early spring, which, in turn, influences the size of the late summer peak population. The peak population size is also affected by short-term weather events possibly acting via the food supply. The effects of weather and food on population growth are in part mediated through competition, including defense of space and suppression of reproduction. The inelasticity of female territories appears to set an upper limit to population density. [source] Effect of experimentally altered food abundance on fat reserves of wintering birdsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2003Christopher M. Rogers Summary 1Current models of adaptive fat regulation make opposing predictions concerning the effect of increased winter food supply on size of the avian winter fat reserve. To distinguish between models, food supply was varied experimentally in nature and two measures of size of the fat reserve were taken at food-supplemented sites and non-supplemented sites. 2In two winters, most of the seven species sampled showed slightly higher visible subcutaneous fat class at supplemented than at non-supplemented sites; treatment and species factors were statistically significant. Body mass corrected for wing length showed a similar if non-significant trend. 3A parallel dispersal study of birds colour-banded at non-supplemented sites showed that these birds did not move 0·8 or 1·5 km to use supplemental food at private feeding stations in the study areas. In addition, accipiter hawk attack rate did not differ between supplemented and non-supplemented sites. 4These results are consistent with a model of adaptive fat regulation (based on between-day environmental variability caused by severe weather events) that predicts an increase in the winter fat reserve at increased food supply. Other published studies, all from the north temperate zone, showed the same pattern. 5The present results are inconsistent with a second model (based on within-day foraging interruption) which predicts a decrease in the fat reserve under increased food supply. However, a set of published studies, all from tropical regions or regions with mild maritime climate, showed the decrease at higher food predicted by the second but not the first model. 6Models of adaptive fat regulation in small birds are therefore limited in their predictive power, perhaps because they are developed for environments that differ in the time scale of environmental stochasticity. New studies are needed that explore further the complexities of environment-specific adaptive fat models, e.g. a winter feeding experiment in a tropical bird species. [source] Fallacies in probability judgments for conjunctions and disjunctions of everyday eventsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 3 2009Fintan J. CostelloArticle first published online: 16 OCT 200 Abstract The conjunction fallacy occurs when people judge a conjunction B-and-A as more probable than a constituent B, contrary to probability theory's ,conjunction rule' that a conjunction cannot be more probable than either constituent. Many studies have demonstrated this fallacy in people's reasoning about various experimental materials. Gigerenzer objects that from a ,frequentist' standpoint probability theory is not valid for these materials, and so failure to follow the conjunction rule is not a fallacy. This paper describes three experiments showing that the conjunction fallacy occurs as consistently for conjunctions where frequentist probability theory is valid (conjunctions of everyday weather events) as for other conjunctions. These experiments also demonstrate a reliable correlation between the occurrence of the conjunction fallacy and the disjunction fallacy (which arises when a disjunction B-or-A is judged less probable than a constituent B). This supports a probability theory,+,random variation account of probabilistic reasoning. Copyright © 2008 John Wiley & Sons, Ltd. [source] Invasibility of grassland and heath communities exposed to extreme weather events , additive effects of diversity resistance and fluctuating physical environmentOIKOS, Issue 10 2008Juergen Kreyling Understanding the resistance of plant communities to invasion is urgent in times of changes in the physical environment due to climate change and changes in the resident communities due to biodiversity loss. Here, we test the interaction between repeated drought or heavy rainfall events and functional diversity of grassland and heath communities on invasibility, measured as the number of plant individuals invading from the matrix vegetation. Invasibility of experimental plant communities was influenced by extreme weather events, although no change in above-ground productivity of the resident communities was observed. Drought decreased invasibility while heavy rainfall increased invasibility, a pattern that is consistent with the fluctuating resource hypothesis. Higher community diversity generally decreased invasibility, which can be explained by a combination of the fluctuating resource hypothesis and niche theory. The effects of the physical environment (extreme weather events) and diversity resistance (community composition) were additive, as they were independent from each other. Differences in the composition of invading species sets were found, and Indicator Species Analysis revealed several invading species with significant affinity to one particular extreme weather event or community composition. This finding supports niche theory and contradicts neutral species assembly. Our data supports theories which predict decreased resistance of plant communities due to both increased climate variability and biodiversity loss. The effects of these two factors, however, appear to be independent from each other. [source] Die Herausforderung globaler KlimawandelPERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 2010Mojib Latif The climate problem is therefore closely linked to the way we produce energy. Climate models predict a massive warming by the end of the century should global greenhouse gas emissions not be strongly reduced. The Intergovernmental Panel on Climate Change (IPCC) reports that the warming can amount to up to 4°C in a worst case scenario, which would be unprecedented in speed and extent in man's history. This can lead to an increase of extreme weather events and a rise of global sea level by up to 1m. A less known impact of increasing atmospheric carbon dioxide is ocean acidification, as the oceans take up large amounts of carbon dioxide. Ocean acidification potentially threatens marine life and global food production. [source] A review of the initiation of precipitating convection in the United KingdomTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 617 2006Lindsay J. Bennett Abstract Recent severe weather events have prompted the European scientific community to assess the current understanding of convective processes with a view to more detailed and accurate forecasting. The initial development of convective cells remains one of the least understood aspects and one in which limited research has taken place. The important processes can be split into three main areas: boundary-layer forcing, upper-level forcing and secondary generation. This paper is a review of the mechanisms responsible for the initiation of precipitating convection in the United Kingdom; i.e. why convective clouds form and develop into precipitating clouds in a particular location. The topography of the United Kingdom has a large influence on the initiation of convection. Boundary-layer forcings determine the specific location where convection is triggered within larger regions of potential instability. These latter regions are created by mesoscale or synoptic-scale features at a higher level such as dry intrusions and mesoscale vortices. Second-generation cells are those formed by the interaction of outflow from convective clouds with the surrounding environmental air. Large, long-lived thunderstorm complexes can develop when new cells are repeatedly triggered on one side of the system. Current and future field campaigns along with the development of high-resolution modelling will enable these processes to be investigated in more detail than has previously been achieved. © Royal Meteorological Society, 2006. Contributions by P. A. Clark and M. E. B. Gray are Crown Copyright. [source] Validation of precipitable water from ECMWF model analyses with GPS and radiosonde data during the MAP SOPTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 612 2005Olivier Bock Abstract Precipitable water vapour contents (PWCs) from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses have been compared with observations from 21 ground-based Global Positioning System receiving stations (GPS) and 14 radiosonde stations (RS), covering central Europe, for the period of the Mesoscale Alpine Programme experiment special observing period (MAP SOP). Two model analyses are considered: one using only conventional data, serving as a control assimilation experiment, and one including additionally most of the non-operational MAP data. Overall, a dry bias of about ,1 kg m,2 (,5.5% of total PWC), with a standard deviation of ,2.6 kg m,2 (13% of total PWC), is diagnosed in both model analyses with respect to GPS. The bias at individual sites is quite variable: from ,4 to ,0 kg m,2. The largest differences are observed at stations located in mountainous areas and/or near the sea, which reveal differences in representativeness. Differences between the two model analyses, and between these analyses and GPS, are investigated in terms of usage and quality of RS data. Biases in RS data are found from comparisons with both model and GPS PWCs. They are confirmed from analysis feedback statistics available at ECMWF. An overall dry bias in RS PWC of 4.5% is found, compared to GPS. The detection of RS biases from comparisons both with the model and GPS indicates that data screening during assimilation was generally effective. However, some RS bias went into the model analyses. Inspection of the time evolution of PWC from the model analyses and GPS occasionally showed differences of up to 5,10 kg m,2. These were associated with severe weather events, with variations in the amount of RS data being assimilated, and with time lags in the PWCs from the two model analyses. Such large differences contribute strongly to the overall observed standard deviations. Good confidence in GPS PWC estimates is gained through this work, even during periods of heavy rain. These results support the future assimilation of GPS data, both for operational weather prediction and for mesoscale simulation studies. Copyright © 2005 Royal Meteorological Society. [source] Silicon-augmented resistance of plants to herbivorous insects: a reviewANNALS OF APPLIED BIOLOGY, Issue 2 2009O.L. Reynolds Abstract Silicon (Si) is one of the most abundant elements in the earth's crust, although its essentiality in plant growth is not clearly established. However, the importance of Si as an element that is particularly beneficial for plants under a range of abiotic and biotic stresses is now beyond doubt. This paper reviews progress in exploring the benefits at two- and three-trophic levels and the underlying mechanism of Si in enhancing the resistance of host plants to herbivorous insects. Numerous studies have shown an enhanced resistance of plants to insect herbivores including folivores, borers, and phloem and xylem feeders. Silicon may act directly on insect herbivores leading to a reduction in insect performance and plant damage. Various indirect effects may also be caused, for example, by delaying herbivore establishment and thus an increased chance of exposure to natural enemies, adverse weather events or control measures that target exposed insects. A further indirect effect of Si may be to increase tolerance of plants to abiotic stresses, notably water stress, which can in turn lead to a reduction in insect numbers and plant damage. There are two mechanisms by which Si is likely to increase resistance to herbivore feeding. Increased physical resistance (constitutive), based on solid amorphous silica, has long been considered the major mechanism of Si-mediated defences of plants, although there is recent evidence for induced physical defence. Physical resistance involves reduced digestibility and/or increased hardness and abrasiveness of plant tissues because of silica deposition, mainly as opaline phytoliths, in various tissues, including epidermal silica cells. Further, there is now evidence that soluble Si is involved in induced chemical defences to insect herbivore attack through the enhanced production of defensive enzymes or possibly the enhanced release of plant volatiles. However, only two studies have tested for the effect of Si on an insect herbivore and third trophic level effects on the herbivore's predators and parasitoids. One study showed no effect of Si on natural enemies, but the methods used were not favourable for the detection of semiochemical-mediated effects. Work recently commenced in Australia is methodologically and conceptually more advanced and an effect of Si on the plants' ability to generate an induced response by acting at the third trophic level was observed. This paper provides the first overview of Si in insect herbivore resistance studies, and highlights novel, recent hypotheses and findings in this area of research. Finally, we make suggestions for future research efforts in the use of Si to enhance plant resistance to insect herbivores. [source] Plant colonization windows in a mesic old field successionAPPLIED VEGETATION SCIENCE, Issue 2 2003Sándor Bartha Abstract. Closed canopy vegetation often prevents the colonization of plant species. Therefore the majority of plant species are expected to appear at the initial phase of post-agricultural succession in mesic forest environment with moderate levels of resources. This hypothesis was tested with data from the Buell-Small Successional Study, NJ, USA, one of the longest continuous fine-scale studies of old-field succession. The study started in 1958, including old fields with different agricultural histories, landscape contexts, and times of abandonment. In each year of the study, the cover values of plant species were recorded in 48 permanent plots of 1 m2 in each field. We analysed the temporal patterns of colonization at plot scale and related these to precipitation data and other community characteristics. The number of colonizing species decreased significantly after ca. 5 yr, coinciding with the development of a continuous canopy of perennial species. However, species turnover remained high throughout the whole successional sequence. The most remarkable phenomenon is the high inter-annual variation of all studied characteristics. We found considerable temporal collapses of vegetation cover that were synchronized among fields despite their different developmental stages and distinctive species compositions. Declines of total cover were correlated with drought events. These events were associated with peaks of local species extinctions and were followed by increased colonization rates. The transitions of major successional stages were often connected to these events. We suggest that plant colonization windows opened by extreme weather events during succession offer optimum periods for intervention in restoration practice. [source] Influence of climate change on the incidence and impact of arenavirus diseases: a speculative assessmentCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2009J. C. Clegg Abstract The current worldwide incidence of viral haemorrhagic fevers caused by arenaviruses is briefly reviewed. The recently published Assessment Report of the Intergovernmental Panel on Climate Change has described the changes in global climate that are expected to occur over the course of the present century and beyond. Climate modelling and forecasting have not yet reached the stage where confident predictions of regional changes at the level of a virus endemic area can be made. However, in the regions where pathogenic arenaviruses now circulate, significant effects are likely to include increases in surface temperature, changes in the extent and distribution of rainfall, the occurrence of extreme weather events, glacier retreat, and coastal flooding as a result of sea level rise. The possible impact of these changes on the geographical location and the incidence of arenavirus diseases and its human impact are discussed. [source] | ||||||||||||||||