Greenhouse warming and vernalisation of high-chill fruit in Southern Australia

Most deciduous fruit trees need sufficient accumulated chilling, or vernalisation, to break winter dormancy. Inadequate chilling due to enhanced greenhouse warming may result in prolonged dormancy, leading to reduced fruit quality and yield. The potential impact of warming on chill accumulation has been analysed using the Utah vernalisation model and temperature data from over 400 climate stations in southern Australia. Two experiments were performed: (i) a sensitivity study where temperatures were increased at all sites by either 1, 2 or 3 °C; (ii) a scenario study for the year 2030 where temperatures were increased according to spatially- and seasonally-varying warming scenarios derived from five global climate models under enhanced greenhouse conditions.The sensitivity study shows that warming causes greater reduction in chilling at sites with a higher present mean temperature and/or a wider diurnal temperature range. In the scenario study, two warming scenarios for the year 2030 were considered: a low (high) warming scenario which assumes a low (high) rate of increase of greenhouse gas emission, a low (high) global climate sensitivity to increased emissions, and a low (high) regional temperature response. The low warming scenario is less than 1 °C in southern Australia and is unlikely to affect the vernalisation of high-chill fruit, except for pome-fruit grown in south-west Western Australia. The high warming scenario exceeds 1.5 °C and would significantly increase the risk of prolonged dormancy for both stone-fruit and pome-fruit at many sites.     

Body and brood sizes of Tenagomysis spp. (Crustacea: Mysida) in southern estuaries in New Zealand

Mysids form a large biomass and mediate the benthic–pelagic coupling of numerous estuaries in southern New Zealand. An intra-annual (2011–2012) field survey in the breeding seasons (i.e. austral spring followed by summer) of mysids Tenagomysis chiltoni and Tenagomysis novaezealandiae, examining the body and brood sizes, was conducted. Samples were collected from six open and eight intermittently open/closed estuaries along the Otago coastline. Brood size of gravid females of T. chiltoni was not significantly related to their body size. Brood size of gravid females of T. novaezealandiae showed a significantly positive relationship with body size in spring but not in summer. It appears that brood size of gravid mysids do not always necessarily depend on body size, but may be influenced by breeding season (e.g. spring) and estuarine typology (e.g. intermittently open/closed).     

Relative abundance of snapper (Chrysophrys auratus) across habitats within an estuarine system

Many fish species rely on estuarine nursery habitats as they transition to adult life stages. Quantifying nursery value, however, requires identification of the life stages (often small and short-lived) that utilise nursery habitats, and survey methods that provide comparable estimates across habitats. We focused our surveys on post-settlement snapper (Chrysophrys auratus) using video camera deployments across habitats within a northeastern New Zealand harbour. Post-settlement snapper abundance was higher among structured habitat types relative to bare sediments, with the type of structured habitat not influential. The exception appeared to be for reef habitat (although sampling was limited). Reef sites were structurally complex, but largely inhabited by older life stages (snapper and other fish species). Overall, nursery value for snapper appears to be connected to structure, rather than structure type. This result emphasises the importance of a broadened scope to coastal fishery management, one that incorporates not just fish extraction, but also habitat maintenance or restoration.     

The potential impact of climate change on Australia's soil organic carbon resources

Background  

Soil organic carbon (SOC) represents a significant pool of carbon within the biosphere. Climatic shifts in temperature and precipitation have a major influence on the decomposition and amount of SOC stored within an ecosystem and that released into the atmosphere. We have linked net primary production (NPP) algorithms, which include the impact of enhanced atmospheric CO₂ on plant growth, to the SOCRATES terrestrial carbon model to estimate changes in SOC for the Australia continent between the years 1990 and 2100 in response to climate changes generated by the CSIRO Mark 2 Global Circulation Model (GCM).     

Changes in the Probability of Heavy Precipitation: Important Indicators of Climatic Change

A simple statistical model of daily precipitation based on the gamma distribution is applied to summer (JJA in Northern Hemisphere, DJF in Southern Hemisphere) data from eight countries: Canada, the United States, Mexico, the former Soviet Union, China, Australia, Norway, and Poland. These constitute more than 40% of the global land mass, and more than 80% of the extratropical land area. It is shown that the shape parameter of this distribution remains relatively stable, while the scale parameter is most variable spatially and temporally. This implies that the changes in mean monthly precipitation totals tend to have the most influence on the heavy precipitation rates in these countries. Observations show that in each country under consideration (except China), mean summer precipitation has increased by at least 5% in the past century. In the USA, Norway, and Australia the frequency of summer precipitation events has also increased, but there is little evidence of such increases in any of the countries considered during the past fifty years. A scenario is considered, whereby mean summer precipitation increases by 5% with no change in the number of days with precipitation or the shape parameter. When applied in the statistical model, the probability of daily precipitation exceeding 25.4 mm (1 inch) in northern countries (Canada, Norway, Russia, and Poland) or 50.8 mm (2 inches) in mid-latitude countries (the USA, Mexico, China, and Australia) increases by about 20% (nearly four times the increase in mean). The contribution of heavy rains (above these thresholds) to the total 5% increase of precipitation is disproportionally high (up to 50%), while heavy rain usually constitutes a significantly smaller fraction of the precipitation events and totals in extratropical regions (but up to 40% in the tropics, e.g., in southern Mexico). Scenarios with moderate changes in the number of days with precipitation coupled with changes in the scale parameter were also investigated and found to produce smaller increases in heavy rainfall but still support the above conclusions. These scenarios give changes in heavy rainfall which are comparable to those observed and are consistent with the greenhouse-gas-induced increases in heavy precipitation simulated by some climate models for the next century. In regions with adequate data coverage such as the eastern two-thirds of contiguous United States, Norway, eastern Australia, and the European part of the former USSR, the statistical model helps to explain the disproportionate high changes in heavy precipitation which have been observed.     

新疆哈密香山西铜镍-钛铁矿床系同源岩浆分异演化产物——矿相学、锆石U-Pb年代学及岩石地球化学证据

香山西岩体是东天山地区发现的唯一的一个铜镍-钛铁复合型含矿岩体,前人对香山西铜镍-钛铁矿床成因认识一直存在争议。本次通过矿相学研究结合电子探针分析,在香山西铜镍矿石中发现了铜镍硫化物与钛铁氧化物共生的现象,并首次测定了香山西钛铁辉长岩的SIMS锆石U-Pb年龄为278.6±1.8Ma(MSWD=1.2),与前人测得香山中岩体角闪辉长岩的锆石U-Pb年龄基本一致,证实了香山西铜镍矿与钛铁矿为共生关系,两者空间上渐变过渡。岩石地球化学研究表明,香山岩体(包括钛铁辉长岩)为同源岩浆经结晶分异作用形成的一套镁铁-超镁铁质岩体,具有拉斑玄武质岩浆分异演化趋势,并且经历了与地壳物质的混染。与中段和东段岩石相比,香山西辉长岩类具有相对高的REE、SiO₂(平均48.99%)、K₂O+Na₂O(平均3.43%)、TiO₂(平均1.26%)和明显低的Mg^#值(平均62.4),表现出分异演化程度高于中段和东段。经反演得出香山岩体原始岩浆含MgO约10%,FeO约9%,TiO₂约1.14%,与同一成矿带内其它含铜镍矿岩体原始岩浆成份相近,应为 普通的拉斑玄武质岩浆。因此,香山西钛铁矿床的形成机制可能是由普通的拉斑玄武质岩浆,经历了较高程度的分异演化导致钛铁氧化物在残余岩浆中逐步富集,岩浆在上升侵位过程中与地壳物质的混染,不仅促使了岩浆中硫化物的饱和,同时提高了岩浆体系的氧逸度,进而促使了钛铁氧化物结晶沉淀。对香山西钛铁矿床成因研究的启示意义在于,除我国攀西地区高钛的玄武质岩浆外,普通的拉斑玄武质岩浆,在有利的分异演化条件下(如初始低氧逸度、相对高度的分异演化、后期与地壳物质混染)也有可能形成大型钛铁矿床。