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Extreme Weather Events (extreme + weather_event)
Selected AbstractsThe 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] 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] 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] | ||||||||||