The nature of eurytopy in polyploid earthworm species in relation to their use in biological soil amelioration

Summary Many of the most widely distributed species of Lumbricidae are polyploid. So far polyploid forms have been found to be distributed more widely than diploid ones. Taking Eisenia nordenskioldi as an example, it was shown that polyploids are able to occupy new ecological niches within the area of the diploid form. Ecological differences observed in representatives of different chromosomal races provide polyploids with the chance to coexist in one biocurrent, occupying different ecological niches.Dedicated to the late Prof. Dr. M.S. Ghilarov     

IPv4/IPv6混合组网技术

文章对IPv4/IPv6混合组网的一些原则进行了讨论,对主要组网技术进行了介绍,提出了最新的一些组网技术选择的方法。     

Impact of topography on cross-pollination in maize (Zea mays L.)

Understanding cross-pollination is important to achieve the coexistence of genetically modified (GM) and conventional maize (Zea mays L.); it is still not known whether topography favors or hinders cross-pollination. In 2005 and 2006, the effect of gradients of 3.4–6.8° on cross-pollination was investigated in the canton of Zurich, Switzerland. Cross-pollination was revealed by the presence of yellow-grains on a white-grain hybrid at distances up to 17.5 m from the yellow-grain pollen donor hybrid. The measurements of the inclination of the slope were based on aerial images data taken by an unmanned GPS/INS (Global Positioning System/Inertial Navigation System)-based and stabilized model helicopter, which delivered precise altitude-based data for sampling points at tassel height.The rate of cross-pollination increased significantly with decreasing altitude of the receptor field (r = 0.36–0.64). However, the effect seems to be weaker than that of other factors like wind direction and velocity.     

松嫩草原羊草与其主要伴生种竞争与共存研究

基于对松嫩草原优势物种羊草(Leymus chi-nensis)及其主要伴生种的空间分布格局、植物种间关系对割草的响应,以及羊草、芦苇(Phragmites communis)对营养和胁迫的适应性与种间关系的研究,探讨了植物竞争和共存的潜在机制。     

千金子与异型莎草对直播水稻产量的影响及其生态经济阈值研究

千金子和异型莎草均是直播稻田的恶性杂草,危害水稻的生长发育,对水稻生产造成严重威胁。为明确千金子和异型莎草对直播稻产量的影响及其生态经济阈值,采用添加系列试验法和模型拟合法研究不同密度千金子和异型莎草组合和与水稻不同共生时间下水稻产量性状的变化规律。结果表明,随着千金子和异型莎草组合密度增加以及与水稻共生时间延长,水稻的有效穗数、每穗实粒数、千粒重和产量均逐渐下降。当千金子+异型莎草密度增加至8株·m~(-2)+8株·m~(-2),水稻产量仅2 236.37kg·hm~(-2),与空白对照相比产量损失率为71.14%;在千金子4.67株·m~(-2)+异型莎草3.50株·m~(-2)的平均密度下,二者与水稻在整个生育期共生时,水稻产量为5 138.33 kg·hm~(-2),与空白对照相比产量损失率为33.37%。低密度、短时间共生的两杂草组合对水稻产量无显著影响。但从密度梯度看,在两种杂草与水稻整个生育期共生条件下,杂草复合密度达到4.14株·m~(-2)时,则必须对其进行防除;从共生时间的尺度看,在试验设置密度条件下,必须在水稻种植后的16.7 d进行杂草防除,否则将对水稻产量和经济效益造成显著影响。在对复合杂草生态经济阈值分析的基础上进行杂草防除,可避免除草剂盲目使用,对减少除草剂使用次数,降低除草剂用量、节约除草成本和保护农田生态环境具有指导作用。     

Environmental filtering vs. resource-based niche partitioning in diverse soil animal assemblages

Terrestrial invertebrates constitute most of described animal biodiversity and soil is a major reservoir of this diversity. In the classical attempt to understand the processes supporting biodiversity, ecologists are currently seeking to unravel the differential roles of environmental filtering and competition for resources in niche partitioning processes: these processes are in principle distinct although they may act simultaneously, interact at multiple spatial and temporal scales, and are often confounded in studies of soil communities. We used a novel combination of methods based on stable isotopes and trait analysis to resolve these processes in diverse oribatid mite assemblages at spatial scales at which competition for resources could in principle be a major driver. We also used a null model approach based on a general neutral model of beta diversity. A large and significant fraction of community variation was explainable in terms of linear and periodic spatial structures in the distribution of organic C, N and soil structure: species were clearly arranged along an environmental, spatially structured gradient. However, competition related trait differences did not map onto the distances separating species along the environmental gradient and neutral models provided a satisfying approximation of beta diversity patterns. The results represent the first robust evidence that in very diverse soil arthropod assemblages resource-based niche partitioning plays a minor role while environmental filtering remains a fundamental driver of species distribution.     

农业机械碰撞系统的全局动力学研究

针对农业机械碰撞动力学系统的运动特性,基于Newton迭代思想,快速精确地定位碰撞时刻,给出一种高效的数值解方法。以一类典型的农业机械碰撞系统为例,借助广义胞映射算法,得到系统共存的多个吸引子的空间布局、吸引盆及清晰的盆边界。     

共生机制下的乡村景观设计初探——以安徽省合肥市庐阳区滁河景观设计为例

阐述了共生机制理论在新农村建设中的引用与发展。指出共生机制中包含运行机制和生长机制,其中生长机制是建立维护稳定地运行机制的措施,融合运行机制中各类机制,促使各类机制正常合理科学地运行,构建乡村的聚居能力,使各类运行机制稳定持续生长。新农村建设中共生性的景观是乡村必须的,使乡村具有发展的可能性和潜力,能稳健地改善人居环境的建设、程度和进展。联系实践案例剖析了乡村景观规划的共生机制。     

Dynamics of nitrogen nutrition of coexisting dominant trees in mixed broad-leaved/Korean pine forest

IntroductionThecapacityofwoodyplantstoassimilateavail-ablenitrogen(nitrateandammonium)hasbeenweIlstudied,especiaIIyintermsofhabitatandspe-cies-reIateddifferencesinnitrateandammoniumassimiIationcapacity(Addoms1937lHauck1968lAlGharbietaI.1984,L8eetaI.1978,Tamm,1991,Vi-touseketaI.,1982iLietaI1994a,1994b,1995)However,nostudyhasfocusedonspecies-specifictemporalvariationinnitrateandammoniumassimiIa-tionamongexplicitIyco-existingwoodyplants,eventhoughtemporaIdifferentiationintheuseofnitratean…     

进水钙、铝离子共存对反渗透膜污染的影响效应分析

基于某生物制药企业膜生物反应器处理出水配置了不同Ca/Al配比的料液,以考察其对反渗透膜污染的结构、形貌、组成与特征的影响效应。结果表明：进水中共存的钙、铝成分结合有机物在膜面上形成了复合污染层,Ca/Al配比的变化导致差异显著的膜污染特性。在低铝含量、高Ca/Al比条件下,进水中铝盐与膜面有机官能团在强势极性作用力下优先结合,与进水中疏水性有机组分凝聚共沉于膜面,对膜污染的形成具有远大于Ca组分的作用。根据扩展杨氏方程计算得到系统总表面张力：低钙低铝,53.0 mJ/m²;低钙高铝,69.5 mJ/m²;高钙高铝,70.4 mJ/m²。这表明进水中铝含量变化主要影响进水溶液与膜面材料之间的极性作用力,钙含量变化几乎没有相应影响。膜清洗结果表明进水中钙铝成分引起的膜污染在空间结构上是分层的,铝通过与膜面分子间的极性力作用紧密结合在膜污染的底层,形成难以清洗的不可逆污染;Ca则主要存在于污染的滤饼层,极易通过化学清洗恢复。因此,精准控制前段混凝预处理阶段Al盐投加量对防止膜污染具有重要意义。