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

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.     

东北黑土区保护性耕作的发展现状与成效研究

东北黑土区承担着国家粮食安全“稳压器”的重要责任。然而,由于长期超负荷开发利用导致黑土日益退化,黑土资源的永续利用受到严重制约。理论与实践证明,保护性耕作是保护黑土地、推动黑土耕地质量和耕作效益绿色增长的发展模式。综述了保护性耕作的基本内涵及其在东北黑土区的发展现状与技术概况,从保护性耕作在土壤保持、保墒效益、结构改善、固碳培肥和土壤生物多样性增加、节本增效等方面系统评估了东北黑土区实施保护性耕作后的生态与经济效益,提出黑土区实施保护性耕作存在的问题与未来发展方向,以促进黑土地保护与利用协调发展、推动保护性耕作高质量跨越式发展。     

Late Quaternary solifluction sheets in the British uplands

Solifluction sheets are large-scale and extensive valley-floor and valley-side landforms developed widely in the British Isles from mass-wasting of glacial and periglacial sediments during late-glacial times. We describe their geographical distribution and review the processes that have led to their development. We use data from the Cheviot Hills, the one site in the British Isles where sedimentology and optically stimulated luminescence dating have been combined, to assess their age and nature of deposition. We also present data from central Wales where a new mapping and resistivity survey has reconstructed the nature of valley-side solifluction sheets. We explore the relative lack of recent research on these landforms and argue that solifluction sheets represent a clear example of how upland geomorphological systems have responded to late-glacial climate change. We end by identifying a number of areas where research on these enigmatic features could be focussed, including better understanding of their distribution, sedimentology and age.     

Magnetic spherules in coastal plain sediments,Sullivan's Island,South Carolina,USA

Abstract— We extracted black, magnetic spherules from well cuttings of Oligocene sediments in the coastal plain of South Carolina, USA. Three possible origins were considered: industrial, volcanic, and extraterrestrial. An extraterrestrial origin by ablation of parent meteoroid material is proposed, based on the spherule morphologies, the presence of metallic Fe cores in many of the spherules, and the detection of wüstite in some of the oxide rims. Low Ni contents are problematic but may be attributed to the ablation of a low-Ni parental body, such as hexahedrite. The presence of spherules in somewhat clay-like, sandy sediments is unusual, as most magnetic spherules are found in abyssal muds. Based on benthic foraminiferal assemblages and sediment distribution above, within, and below the beds containing spherules, it is unlikely that the spherules were transported from a deep-sea environment.     

Canonical planetary perturbation equations for velocity-dependent forces,and the Lense-Thirring precession

A form of planetary perturbation theory based on canonical equations of motion, rather than on the use of osculating orbital elements, is developed and applied to several problems of interest. It is proved that, with appropriately selected initial conditions on the orbital elements, the two forms of perturbation theory give rise to identical predictions for the observable coordinates and velocities, while the orbital elements themselves may be strikingly different. Differences between the canonical form of perturbation theory and the classical Lagrange planetary perturbation equations are discussed. The canonical form of perturbation theory in some cases has advantages when the perturbing forces are velocity-dependent, but the two forms of perturbation theory are equivalent if the perturbing forces are dependent only on position and not on velocity. The canonical form of the planetary perturbation equations are derived and applied to the Lense Thirring precession of a test body in a Keplerian orbit around a rotating mass source.     

Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction

A primary step in the interpretation of speleothem stable isotope records (¹⁸O/¹⁶O and ¹³C/¹²C) is to conduct a comparison with other local palaeoclimate proxies. Here, two new master speleothem δ¹⁸O and δ¹³C records (one from eastern North Island, and the other from western/southern South Island, New Zealand) are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential. This comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification [Lorrey, A.M., Fowler, A.M., Salinger, J., 2007a. Regional climate regime classification as a qualitative tool for interpreting multi-proxy palaeoclimate data spatial patterns: a New Zealand case study. Palaeo-3, in press], specifically because these two regional climate districts are hyper-sensitive to westerly circulation changes, and in many cases, exhibit contrasting climate character in response to circulation anomalies.For both the western South Island and the eastern North Island master speleothem δ¹³C records, variations tracked changes in relative regional precipitation. The δ¹⁸O master speleothem record for both regions varied with temperature change. Both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction. The ensuing attempt at a multi-proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the New Zealand sector has varied considerably during the past four millennia. Centennial-scale circulation changes for the past 4000 years are evident, and are analogous to modern Blocking, Zonal and Trough regime types [Kidson J. W., 2000. An analysis of New Zealand synoptic types and their use in defining weather regimes. International Journal of Climatology 20, 299–316] that characterise changes in present-day (prevailing) westerly circulation. This palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here, and it can likely be improved on with better dating control and the addition of new records with higher resolution. It is also anticipated that future work will expand to include more proxy data from across New Zealand to improve the clarity of past climate regime occurrence for the Late Holocene.     

Inversion of sonic waveforms with unknown source and receiver functions

A seismogram that is several times the length of the source-receiver wavelet is windowed into two parts—these may overlap—to obtain two seismograms with approximately the same source function but different Green's functions. A similarly windowed synthetic seismogram gives two corresponding synthetic seismograms. The spectral product of the window 1 data with the window 2 synthetic is equal to the spectral product of the window 1 synthetic with the window 2 data only if the correct earth model is used to compute the synthetic. This partition principle is applied to well-log sonic waveform data from Ocean Drilling Project hole 806B, a slow formation, and used there to estimate Poisson's ratio from a single seismogram whose transmitter and receiver functions are unknown. A multichannel extension of the algorithm gives even better results. The effective borehole radius R _b, was included in the inversion procedure, because of waveform sensitivity to R _b. Inversion results for R _b agreed with the sonic caliper, but not the mechanical caliper; thus if R _b is not included in the inversion its value should be taken from the sonic caliper.