Pollination of the invasive exotic shrub Lupinus arboreus (Fabaceae) by introduced bees in Tasmania

Exotic plant invasions threaten ecological communities world-wide. Some species are limited by a lack of suitable pollinators, but the introduction of exotic pollinators can facilitate rapid spread. In Tasmania, where many non-native plants are naturalised, exotic honeybees (Apis mellifera) and bumblebees (Bombus terrestris) have become established. We determined how these species affect the pollination of Lupinus arboreus, an invasive, nitrogen-fixing shrub, which is rarely visited by native pollinators. The proportion of flowers setting seed and the number of ovules fertilised per flower were positively related to the visitation rates of both exotic bee species. There was no effect of bee visitation rates on the proportion of seeds aborted prior to maturity, possibly due to post-fertilisation environmental constraints. We conclude that the spread of B. terrestris may not alter the fecundity of L. arboreus because of the pollination service provided by A. mellifera, and discuss potential interactions between these two bee species.     

Field compaction at different soil-water status: effects on pore size distribution and soil water characteristics of a Rhodic Ferralsol in Western Cuba

The level of compaction induced on cultivated fields through trafficking is strongly influenced by the prevailing soil-water status and, depending on the attendant soil degradation, vital soil hydraulic processes could be affected. Therefore, understanding the relationship between field soil-water status and the corresponding level of induced compaction for a given load is considered an imperative step toward a better control of the occurrence of traffic-induced field soil compaction. Pore size distribution, a fundamental and highly degradable soil property, was measured in a Rhodic Ferralsol, the most productive and extensively distributed soil in Western Cuba, to study the effects of three levels of soil compaction on soil water characteristic parameters. Soil bulk density and cone penetration index were used to measure compaction levels established by seven passes of a 10 Mg tractor at three soil-water statuses corresponding to the plastic (Fs), friable (Fc) and relatively dry soil (Ds) consistency states. Pore size distribution calculated from soil water characteristic curves was classified into three pore size categories on the basis of their hydraulic functioning: >50 μm (f_>50 μm), 50–0.5 μm (f_{50–0.5 μm}) and <0.5 μm (f_<0.5 μm). The greatest compaction levels were attained in the Fs and Fc soil water treatments, and a significant contribution to compaction was attributed to the existing soil water states under which the soil compaction was accomplished. Average cone index (CI) values in the range of 2.93–3.70 MPa reflected the accumulation of f_<0.5 μm pores, and incurred severe reductions in the volume of f_>50 μm pores in the Fs and Fc treatments, while an average CI value of 1.69 MPa indicated increments in the volume of f_{50–0.5 μm} in the Ds treatment. Despite the differential effects of soil compaction on the distribution of the different pore size categories, soil total porosity (f_Total) was not effective in reflecting treatment effects. Soil water desorption at the soil water potentials evaluated (0.0 to −15,000 cm H₂O) was adversely affected in the f_<0.5 μm dominated treatments; strong soil water retention was observed with the predominance of f_<0.5 μm, as was confirmed by the high water content at plant wilting point. Based on these findings, the use of field capacity water content as the upper limit of plant available soil water was therefore considered inappropriate for compacted soils.     

投影寻踪技术在松嫩平原西部水资源可持续利用中的应用

根据松嫩平原西部水资源复合系统的特征和水资源条件,建立了区域水资源可持续利用评价指标体系。应用投影寻踪技术,采用实码遗传算法优化投影指标函数,将方案多维评价指标值综合为一维投影值,根据投影值的大小实现方案的优选。研究表明,投影寻踪技术可以有效地解决权重的人为干扰,通过优化排序实现对评价结果的定量化表征。     

Lichens and bryophytes on Eucalyptus obliqua in Tasmania: management implications in production forests

Thirty lichen and 25 bryophyte species have been recorded from the buttresses of Eucalyptus obliqua, the dominant tree in wet sclerophyll forest at the Warra Long-Term Ecological Research Site in southern Tasmania. The flora, characterised by four major associations, is very distinctive, containing a relatively high number of eucalypt specialists, particularly among the lichens. A general trend towards increasing species richness with increasing tree diameter is apparent and is attributed mainly to increasing habitat diversity on the buttresses. The increase in species occurs without the loss of pioneers; thus succession involves addition rather than replacement of species. The relationships between epiphytes, tree age and forest age are complicated by the periodic occurrence of fires in the forest. Nevertheless, potential oldgrowth indicators are identified and the possible effects of current silvicultural practices on the conservation of the species are discussed.     

Composition,distribution and sources of polycyclic aromatic hydrocarbons in sediments of the western harbour of alexandria,egypt

Aim and Background  Little data are available on the levels of polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Mediterranean Sea Coast of Egypt in general and the Alexandria coastal zone in particular. It was therefore deemed necessary to set up a monitoring programme to determine the current concentrations of PAHs in bottom sediments, and to identify any area where high concentrations of these potential hazardous contaminants were present in the Western Harbour of Alexandria. Methods  The composition, distribution and the source of PAHs in surficial sediments of the harbour were investigated. To document the spatial PAH input, surficial sediment samples from 23 locations throughout the harbour were analysed. as]Results and Discussion The total PAH load determined in the surficial sediment samples ranged from 8 to 131150 ng g¹ dry wt, generally with most of the samples having total concentrations of PAHs greater than 5000 ng g¹ dry weight. The highest concentration of total PAHs was recorded in sediments of the inner harbour. Ratio values of specific compounds such as phenanthrene to anthracene, fluoranthrene to pyrene, methyl-phen-anthrene to phenanthrene, methyl-dibenzothiophenes to dibenzothiophenes, alkylated to non-alkylated and high molecular weight to low molecular weight PAH, were calculated to evaluate the possible source of PAH contamination in the harbour sediments. Conclusions  Two main sources of PAH in the study area have been found: pyrolytic and petrogenic. Interferences of rather petrogenic and pyrolytic PAH contaminations were noticed for most samples. The dominant sources of PAH appear to be the combustion processes through run-off, industrial and sewage discharges, and atmospheric input. The concentrations of PAHs were generally above levels expected to cause adverse biological effects. Recommendations and outlook  Information from this study and any other relevant studies should be useful in designing future strategies for environmental protection and management of the harbour.     

防控有害入侵生物——西花蓟马

西花蓟马(Frankliniella occidentalis)是一种世界著名的危险性害虫,我国大陆于2003年首次报道。西花蓟马的发生给农作物造成严重危害和经济损失。本文就西花蓟马的寄主与危害及其防控等方面进行了概述。     

豫西地区不同类型农田化肥增产效益及增产潜力研究

 【目的】探讨化肥在豫西地区不同地形农田的增产效益与增产潜力，为引导和实现化肥的优化配置和合理施用、提高豫西地区粮食产量提供参考依据。【方法】采用田间试验，研究了豫西地区平川地、坡平地、坡地等3种典型地形农田化肥施用量对作物产量的影响；并对3种典型农田化肥消费量与粮食产量的多年统计资料进行了分析，提出了二者之间的关系，并由此对豫西地区粮食增产潜力进行了预测。【结果】作物单产以平川地最高，坡平地次之，坡地最低。尽管在3种类型农田上使用化肥均可大幅度增加作物产量，但化肥增产效益以坡地最高，坡平地次之，平川地最低；对3种典型地形农田化肥消费量与粮食产量多年统计资料的分析也获得相同结论。根据田间试验结果对未来豫西地区粮食产量及增产潜力进行的预测表明，当采用本研究中最大施肥量时，豫西地区粮食总产量可达到4.24×109 kg，是2003年该地区粮食产量的2.1倍；并预测在增加粮食产量中，坡地贡献率占50.1%、坡平地占33.7%、平川地占16.2%，坡地和坡平地粮食生产对该地区粮食总产量具有决定作用。【结论】豫西地区3种典型地形农田中化肥增产效益存在差异，以坡地化肥增产效益最大。因此，加强坡地化肥投入，可有效地提高本区粮食总产量，对今后本区粮食的增产具有重要意义。     

豫西地区石粉矿物元素含量分析

对豫西地区石粉中矿物元素的含量进行检测,结果表明,石粉中含有丰富的钙和铁等元素。其中龙门山石粉中钙的含量为18.00%,铁含量为4 357.36 mg/kg;新安县石粉中钙的含量为32.77%,铁含量为5 398.06 mg/kg。2种石粉是补充禽用饲料中钙、铁等元素的良好来源。     

西花蓟马(Frankliniella occidentalis)研究进展*

 西花蓟马(Frankliniella occidentalis)属于缨翅目(Thysanoptera)昆虫,最初分布于美国西部,20世纪80年代开始迅速扩散至全球各大洲,目前已在69个国家和地区有报道,成为世界性害虫。F. occidentalis可以以持久性的方式传播番茄斑萎病毒属(Tospovirus)病毒,如番茄斑萎病毒(tomato spotted wilt virus, TSWV);并且,F. occidentalis传播的病毒所造成的经济损失远远大于其本身所造成的损失。因此控制F. occidentalis的种群以及它的扩散是控制Tospoviruses的关键所在,有鉴于此,各国对F. occidentalis进行了深入的研究。主要论述了近年来F. occidentalis在生物学特征、室内饲养以及它和TSWV的互作关系等方面的进展。     

自拟中草药复方防治蛋雏鸡大肠杆菌病的研究

用自拟中草药复方对蛋雏鸡大肠杆菌病进行了病原菌体外药物敏感试验、中西药疗效对比试验及临床治疗和预防试验,并对自拟中草药复方进行了有效治疗剂量筛选试验和安全性试验。结果表明,自拟中草药复方对各生长阶段蛋雏鸡的安全性高,对大肠杆菌中度敏感;在饲料中有效治疗添加量为10g/kg,在治疗蛋雏鸡大肠杆菌病时获得了较好的治疗效果(有效率88.3%),但采取中西医合并治疗效果最好(有效率96.7%),与西药组和中药组相比差异显著(P<0.05);使用自拟中草药复方在临床上预防大肠杆菌病,发病率明显低于西药组,且二者差异显著(P<0.05);按8倍剂量使用仍较安全,未出现异常表现,剖检和组织切片检查也未发现异常变化。