The Vulnerability of the Australian Beef Industry to Impacts of the Cattle Tick (Boophilus microplus) under Climate Change     

Neil White  Robert W. Sutherst  Nigel Hall  Patrick Whish-Wilson 《Climatic change》2003,61(1-2):157-190

An integrated assessment is presented of the potential impacts of the cattle tick (Boophilus microplus Canestrini) on the Australian beefindustry under climate change. The project was carried out as a case study to test an impact assessment approach that was designed to integrate biological, production and socio-economic impacts on managed and natural systems. A climate-driven, tick population model was run for European, zebu and crossbred cattle breeds having different levels of resistance to cattle ticks. A geographical information system (GIS) was used to organise spatial data on climate scenarios and industry statistics and to undertake regional analyses.A comparison was made of the two available approaches to conducting impact assessments, namely a bottom-up approach using sensitivity analysis and a top-down approach using climate change scenarios from a global circulation model (GCM) (CSIRO, 1996). The output, in terms of the abundance of tick populations and reductions in cattle productivity for each breed showed significant expansions in potential geographical impacts. In the absence of any adaptation measures, the results indicated changes in the losses in live weight gain of cattle tick ranging from 7780 tonnes per year by 2030 to 21637 tonnes per year by 2100, in comparison with estimates for current losses of 6594 tonnes per year.The principal adaptation options available to the beef industry are to switch to breeds that are more resistant to cattle ticks, or to increase the frequency of treatments with various tick control products. In this paper we focus on switching breeds as an adaptive measure when appropriate damage thresholds are triggered under the climate change scenarios. When adaptation measures were put in place, the losses ranged from 4962 tonnes in 2030 to 5619 tonnes in 2100 compared with 2636 tonnes at present if all producers adopted the optimal breed structure. Optimal breed structure was defined as one that would prevent tick numbers per animal exceeding 100 ticks per animal for European and 700 ticks per animal for crossbred breeds of cattle in any week of the year under a tick control strategy that was suitable for present climatic conditions. The lower threshold for European breeds reflects their vulnerability to explosive increases in numbers because of their low resistance to ticks. The results of the analyses using the GCM scenarios were used in an economic model to calculate costs of lost live-weight gain for 2030, 2070 and 2100. The greatest increases in costs were incurred in the southern parts of the current distribution in Queensland and potentially in northern New South Wales if the present quarantine barrier failed.Given the great uncertainty of the nature of possible regional changes in climate, analyses of the sensitivity of losses in live weight gain to changes in climatic variables were also undertaken. The analyses included a measure of likely impacts of cattle tick on the beef cattle industry, in the absence of adaptation measures, as a baseline measure of sensitivity. The likely impacts on crossbred cattle were insensitive to the climatic variables.When adaptive breed changes were allowed, the economic impacts on the industry were insensitive to the GCM scenarios. This suggests that, at least in this instance, reducing the uncertainties in climate change scenarios is not a priority if the adaptation strategies can be implemented in a cost-effective manner. Finally we made a qualitative assessment of the sustainability and robustness of alternative approaches to adaptation and assessed regional vulnerability to cattle tick under climate change. The conclusions were so strongly dependent on assumptions about the future of other global changes, in particular the ability to maintain quarantine barriers and to retain effective acaricides at comparable costs to the present, that we strongly recommend that risk assessments of climate change extend to all relevant variables in involved in global change where possible.  相似文献   

Induced stresses and fault potential in eastern Canada due to a realistic load: a preliminary analysis   总被引：1，自引：0，他引：1  

Patrick Wu  Henry S. Hasegawa 《Geophysical Journal International》1996,127(1):215-229

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Measurement of natural stresses in a Provence mine (Southern France)     

Patrick Gaviglio  Pascal Bigarre  Hafid Baroudi  Jack-Pierre Piguet  Raymond Monteau 《Engineering Geology》1996,44(1-4):77-92

Stress measurements were carried out in the Arc syncline using drifs in a lignite mine. Eleven sites were investigated using the flat jack and hydraulic fracturing (or stimulating) methods. Two stress states were found to coexist, one isotropic, the other highly anisotropic. The orientations of the principal stresses are not homogeneous and an orientation ranging from E-W to NE-SW predominates locally. This does not accord with the regional stress field. The vertical stresses are systematically underestimated.  相似文献   

Geochemistry of the Rare Earth Elements in Natural Terrestrial Waters：A Review of What Is Currently Knows   总被引：3，自引：0，他引：3  

KEVIN  H  JOHANNESSON ZHOUXIAOPING 《中国地球化学学报》1997,16(1):20-42

The range of observed chemical compositions of natural terrestrial waters varies greatly especially when compared to the essentially constant global composition of the oceans.The concentrations of the REEs in natural terrestrial waters also exhibit more variation than what was reported in seawater,In terrestrial waters ,pH values span the range from acid up to alkaline,In addition,terrestrial waters can range from very dilute waters through to highly concentrated brines.The REE concentrations and their behavior in natural terrestrial waters reflect these compositional ranges,Chemical weathering of rocks represents the source of the REEs to natural terrestrial waters and ,consequently,the REE signature of rocks can impart their REE signature to associated waters,In addition,Because of the typical low solubilities of the REEs both surface and solution complexation can be important in fractionating REEs in aqueous solution.Both of these processes are important in all natural terrestrial waters,however,their relative importance varies as a function of the overall solution composition,In alkaline waters,for example,Solution complexation of the REEs with carbonate ions appears to control their aqueous distributions whereas in acid waters,the REE signature of the labile fraction of the REEs is readily leached from the rocks.In circumneutral pH waters,both processes appear to be important and their relative significance has not yet been determined.  相似文献   

The Maltese Islands: climate, vegetation and landscape   总被引：1，自引：0，他引：1  

Patrick J. Schembri 《GeoJournal》1997,41(2):1-11

The Maltese Islands, situated in the central Mediterranean, occupy an area of only some 316 km². The climate is typically Mediterranean: the average annual rainfall is c. 530 mm of which some 85% falls during the period October to March; the mean monthly temperature range is 12--26 °C, and the islands are very windy and sunny. Although small, the Maltese Islands have a considerable diversity of landscapes and ecosystems which are representative of the range and variety of those of the Mediterranean region. The islands are composed mainly of limestones, the soils are young and are very similar to the parent rocks, and there are no mountains, streams or lakes, but only minor springs; the main geomorphological features are karstic limestone plateaux, hillsides covered with clay taluses, gently rolling limestone plains, valleys which drain runoff during the wet season, steep sea-cliffs on the south-western coasts, and gently sloping rocky shores to the Northeast. The main vegetational assemblages are maquis, garigue and steppe; minor ones include patches of woodland, coastal wetlands, sand dunes, freshwater, and rupestral communities; the latter are the most scientifically important in view of the large number of endemic species they support. Human impact is significant. Some 38% of the land area is cultivated, c. 15% is built up, and the rest is countryside. The present landscape is a result of the interaction of geology and climate, coupled with the intense human exploitation of the environment over many thousands of years, which has altered the original condition of the vegetation cover, principally through the diversion of vast tracts of land to cultivation, the construction of terraces, water catchment devices, irrigation channels and drainage ditches, the grazing of animals on uncultivated land, and the development of land for buildings and industry. The scantiness of the soil, combined with the erratic rainfall and the periodic disturbance of the vegetation cover, has resulted in extensive erosion. As a consequence it is now difficult for the original vegetation to reassert itself, affecting the landscape drastically and permanently. Much of the original native flora has been lost or marginalised and the present day non-urban landscape is now dominated by vegetation consisting mainly of ruderal and introduced species. As the population increases, and human pressure on the environment mounts, such trends are likely to continue and it is only very recently that some important initiatives have been taken to manage the environment and halt the deterioration of the landscape.  相似文献   

Geochemistry of Tertiary tholeiites and picrites from Qeqertarssuaq (Disko Island) and Nuussuaq, West Greenland with implications for the mineral potential of comagmatic intrusions   总被引：10，自引：0，他引：10  

Peter C. Lightfoot  Christopher J. Hawkesworth  Kevin Olshefsky  Tony Green  Will Doherty  Reid R. Keays 《Contributions to Mineralogy and Petrology》1997,128(2-3):139-163

Tertiary continental flood basalts on Qeqertarssuaq and Nuussuaq in West Greenland contain ～3?km of picrites and variably contaminated tholeiites. The picrites are in the Naujánguit member of the Vaïgat Formation and they have 7–29?wt% MgO, La/Sm?=?0.9–2.1, and ¹⁴³Nd/¹⁴⁴Nd?=?0.51263–0.51307. They appear to have crystallised from high-Mg parental magmas (14.4–16.4?wt% MgO) with isotope and trace element ratios similar to recent Icelandic picrites. Discrete horizons of tholeiites, including the Asûk and?Kûgánguaq, have elevated SiO₂ (50–58 wt%), La/Sm?=?3–7, ⁸⁷Sr/⁸⁶Sr?=?0.70550–0.71224, and low ¹⁴³Nd/¹⁴⁴Nd?=?0.51234–0.51174. These lavas have low Cu and Ni abundances (typically 10–50?ppm Ni or Cu), and in the case of the Asûk on Qeqertarssuaq, they contain droplets of native iron. The low Cu and Ni contents are attributed to scavenging by magmatic sulphides formed in response to crustal contamination of picritic magmas. Two contamination trends are recognised, one to a sediment end-member with high Th/Nb and Archaean model Nd ages, and the other to a meta-igneous component with high La/Sm, low Th/Nb and Rb/Nb, and Proterozoic source ages. Overall, ²⁰⁶Pb/²⁰⁴Pb varies from 16.47–21.68. Both contamination trends are associated with low Cu and Ni, and high SiO₂, and it is argued that the magmatic sulphides were triggered by the increases in silica, rather than simply by the introduction of additional crustal-derived sulphur. Geochemically, the Asûk and Kûgánguaq rocks resemble the most contaminated Nadezhdinsky lavas of the Siberian Trap, which are widely regarded as the source of the Ni and Cu mineralisation in the giant Noril'sk deposits. Mass balance considerations indicate that the parental liquids to the contaminated magmas contained sufficient Ni, Cu, S and platinum group elements to form substantial magmatic sulphide deposits. However, unlike the lavas at Noril'sk, the contaminated (low Cu and Ni) West Greenland basalts are in isolated units with no evidence for a gradual recovery in Ni and Cu abundances with height in the lava column. Comparison with Noril'sk suggests that although significant quantities of metals were scavenged by sulphides in West Greenland, the metal contents of the sulphides may not have been upgraded by continued interaction with subsequent magma batches.  相似文献   

Evidence for freeze–thaw events and their implications for rock weathering in northern Canada     

Kevin Hall 《地球表面变化过程与地形》2004,29(1):43-57

Discussions regarding weathering in cold environments generally centre on mechanical processes and on the freeze–thaw mechanism in particular. Despite the almost ubiquitous assumption of freeze–thaw weathering, unequivocal proof of interstitial rock water actually freezing and thawing is singularly lacking. Equally, many studies have used the crossing of 0 °C, or values close to that, as the basis for determining the number of ‘freeze–thaw events’. In order to assess the weathering regime at a site in northern Canada, temperatures were collected at the surface, 1 cm and 3 cm depth for sets of paving bricks, with exposures both vertical and at 45°, orientated to the four cardinal directions. Temperature data were collected at 1 min intervals for 1 year. These data provide unequivocal proof for the occurrence of the freezing and thawing of water on and within the rock (freeze–thaw events). The freeze event is evidenced by the exotherm associated with the release of latent heat as the water actually freezes. This is thought to be the ?rst record of such events from a ?eld situation. More signi?cantly, it was found that the temperature at which freezing occurred varied signi?cantly through the year and that on occasion the 1 cm depth froze prior to the rock surface. The change in freeze temperature is thought to be due to the chemical weathering of the material (coupled with on‐going salt inputs via the melting of snowfall), which, it is shown, could occur throughout the winter despite air temperatures down to ?30 °C. This ?nding regarding chemical weathering is also considered to be highly signi?cant. A number of thermal stress events were also recorded, suggesting that rock weathering in cold regions is a synergistic combination of various chemical and mechanical weathering mechanisms. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

L'archivage des activités humaines par les neiges et glaces polaires : le cas du plomb     

Claude Boutron  Kevin Rosman  Carlo Barbante  Michael Bolshov  Freddy Adams  Sungmin Hong  Christophe Ferrari 《Comptes Rendus Geoscience》2004,336(10):847-867

The investigation of the occurrence of lead in dated snow and ice from Greenland and Antarctica has played a major role in our understanding of the history of the pollution of the atmosphere of our planet by this metal. Such studies have however proved to be very demanding, mainly because of the extreme purity of polar snow and ice. Reliable measurements can be obtained only if ultra-clean and highly sensitive procedures are used, as pioneered by Clair Patterson. The Greenland data show evidence of large-scale pollution of the atmosphere of the Northern Hemisphere for lead as early as two millennia ago during Greco–Roman times, especially because of mining and smelting activities in southern Spain. It peaked at the end of the 1960s, with lead concentrations in snow about 200 times higher than natural values, before declining during recent times because of the fall in the use of leaded gasoline. Lead pollution in Antarctica was already significant at the end of the 19th century as a consequence of whaling activities, the traffic of coal-powered ships crossing the Cape Horn, and mining activities in South America, South Africa and Australia. After declining because of the opening of the Panama Canal, the great economic depression and World War II, it reached a maximum during the 1980s, with lead concentrations 20 times higher than natural values. Other studies focus on past natural variations of lead in ancient ice dated from the last climatic cycles. To cite this article: C. Boutron et al., C. R. Geoscience 336 (2004).  相似文献   

Caractéristiques et signification d'un niveau coquillier majeur à brachiopodes,marqueur événementiel dans l'évolution dévonienne de la Saoura (Sahara du Nord-Ouest,Algérie)     

Abdelkader Ouali Mehadji  Serge Elmi  Patrick Rachebœuf  Larbi Mekahli 《Comptes Rendus Geoscience》2004,336(14):1283-1292

In the Saoura, the brachiopod shell beds, so-called niveau coralligène, correspond to a major shell deposit dated to the Late Emsian. Brachiopods and crinoids dominate the benthic assemblage that contains also corals, bryozoans, trilobites, goniatites, and orthocones. This major level has a large geographic distribution and it is characterized by a wide brachiopod diversity due to time-averaging, taphonomic feedback and alternate bottom conditions changing from soft to shelly and firm. This kind of brachiopod association is linked to a transgressive onlap system. At regional extent, we can correlate this major shell bed to similar shell deposits from the Ahnet-Mouydir, Tindouf, and Zemmour areas. It indicates an important transgressive event underlined by change in the sedimentation from detritic deposits to carbonate sediments. To cite this article: A. Ouali Mehadji et al., C. R. Geoscience 336 (2004).  相似文献   

Atlantic sources of the Arctic Ocean surface and halocline waters   总被引：8，自引：0，他引：8  

Bert Rudels  E. Peter Jones  Ursula Schauer  Patrick Eriksson 《Polar research》2004,23(2):181-208

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