Uncertainty as the overlap of alternate conditional distributions

An important task in modern geostatistics is the assessment and quantification of resource and reserve uncertainty. This uncertainty is valuable support information for many management decisions. Uncertainty at specific locations and uncertainty in the global resource is of interest. There are many different methods to build models of uncertainty, including Kriging, Cokriging, and Inverse Distance. Each method leads to different results. A method is proposed to combine local uncertainties predicted by different models to obtain a combined measure of uncertainty that combines good features of each alternative. The new estimator is the overlap of alternate conditional distributions.     

Diets of mammalian herbivores in Australian arid, hilly shrublands: seasonal effects on overlap between euros (hill kangaroos), sheep and feral goats, and on dietary niche breadths and electivities

The diets of euros or hill kangaroos (Macropus robustus), domestic sheep (Ovis aries) and feral goats (Capra hircus) in hilly, shrub rangeland in southern Australia were examined in a 12-year study. Levels of dietary overlap between these herbivores, their foraging in relation to resource availability, and the potential for competition in different conditions were also examined. The diet of euros was based around grasses. In dry seasons some shrubs were also eaten but in severe drought grass formed more than 80% of their diet. While grass was important to sheep in wetter conditions, they ate much shrub in dry conditions. Feral goats had broad diets but their preference for browse was high. In drought, euros had only a modest dietary overlap with sheep and goats. Data for dietary niche breadths and electivities pointed to only limited competition between the herbivores.     

傅立叶相位分析导风技术的适用范围和相位重叠分析

本文利用傅立叶相位分析法对示踪云进行频域波谱分析，通过谐波的相位变化计算波速，从而导出云迹风(Cloud Motion Wind—CMW)。本文研究表明，对于给定的导风云图序列，如果示踪云在给定时间间隔内的位移小于两个像距，适用傅立叶相位分析法计算云迹风；否则，在用傅立叶相位分析法计算波速时由于高次谐波出现相位重叠，从而使计算的波速小于实际风速，此时适用最大相关系数法。     

基于EzMap的矢量专题图与影像专题图编制的比较研究

矢量专题图与影像专题图的区别在于是否具有影像内容以及矢量要素内容的选取和表示。本文基于Ez Map软件,从制图工艺流程、地理底图、专题要素内容、符号库设计、制图综合、表示方法、数据量和成图周期8个方面比较,详细讨论了矢量专题图与影像专题图编制的异同,指出了影像专题图的一些优势。     

气候模式中云的垂直重叠及其辐射传输问题研究进展

概述了全球气候模式中云的垂直重叠的处理方法及其辐射物理过程的最新研究进展。从云垂直重叠模型的构造、模型在气候模式中的实现方式,得到与观测一致的云重叠结构所采用的数据和方法、重叠云的辐射传输等方面,给出了针对这一国际研究难点问题的最新研究进展。关于气候模式中云的垂直重叠问题的研究至今已取得了许多成果,表现在:重叠模型上有了更为科学的描述形式(如指数衰减重叠);重叠云的辐射传输也有了更快速的处理方法(如蒙特卡洛独立柱近似)并被广泛应用;连续的三维云遥感观测(如CloudSat/CALIPSO)和云分辨尺度的三维云模式的发展为在气候模式中精确描述云的垂直结构提供了丰富的观测资料和模式数据。但是,气候模式中现有的云重叠结构处理及其辐射传输方法还远不够完善,仍然存在很多没有解决的问题需要在未来进行探索。     

甘肃酒泉荒漠戈壁灌木群落优势物种生态位特征

了解物种利用资源和占据生态空间的能力,对维持完善和科学保育荒漠戈壁植物群落的多样性具有重要意义。在综合反映各生态因子作用的群落类型和海拔梯度组合而成的两条资源轴上,测度分析了甘肃酒泉荒漠戈壁灌木群落主要优势种的生态位特征。结果表明：(1)在群落类型和海拔梯度两条资源轴上,红砂（Reaumuria songarica）、泡泡刺（Nitraria sphaerocarpa）和合头草（Sympegma regelii）的重要值和生态位宽度均较大,说明这些物种适应能力强,能够较好地利用环境资源,分布范围大,作为荒漠戈壁灌木群落中的广域种具有重要的生态地位和作用。(2)荒漠戈壁优势物种间的生态位重叠值多数较小,在群落类型和海拔梯度资源轴上生态位重叠值小于0.5的分别占总种对的62.63%和77.89%。生态位宽度大的物种之间一般生态位重叠值较高,物种利用资源能力强且存在竞争关系;然而,生态位宽度较小的物种与其他物种之间的生态位重叠程度较低,不同物种在环境资源的需求上产生互补,可以和谐共存;生态位宽度小的物种之间生态位重叠值仍较高,物种分布呈斑块现象;因此,生态位重叠与生态位宽度之间无显著相关性。(3)荒漠戈壁优势物种间总体表现为不显著的正关联,表明该植被群落结构及其物种之间处于稳定共存的状态。     

从东江调水后契爷石水库的水质和浮游植物群落结构特征

本文比较了太湖梅梁湾敞水区2004年秋季渔汛期刀鲚(Coilia ectenes)和间下鱵(Hyporhamphus intermedius)的食性,同时对不同食物的重要性、选择性以及两种鱼类食物的重叠进行了分析.结果表明,秋季刀鲚、间下鱵的食物主要由浮游甲壳动物、鱼和昆虫等组成.镖水蚤中的指状许水蚤(Schmackeria inopinus)是刀鲚最重要的食物,而间下鱵最重要的食物是裸腹溞(Moina sp.),而且摄食鱼和昆虫的比例远高于刀鲚.刀鲚和间下鱵对个体较大的指状许水蚤的选择性都比较高,对个体较小、而在太湖密度很高的象鼻溞(Bosmina spp.)都表现出主动回避.刀鲚与间下鱵的食物重叠系数较高,表明对竞争比较激烈,但要完全了解这两种鱼类的竞争关系,还要对它们在太湖的分布,不同发育阶段和不同季节的摄食情况进行详细的调查研究.     

Community structure of infaunal macrobenthos around vestimentiferan thickets at the San Clemente cold seep,NE Pacific

The San Clemente cold seep lies within 100–200 km of other reducing habitats in the NE Pacific, offering an opportunity to compare diversity and species overlap among reducing habitats (i.e. whale‐, kelp‐, and wood‐falls) at similar depths within a single region. Video observations from the research submersible Alvin at the San Clemente seep (1800 m depth) indicated clumps (‘thickets’) of vestimentiferans distributed as meter‐scale patches interspersed with vesicomyid clam beds and black sediments. Sediment‐core samples were collected at distances of 0 to 80–200 m along randomly oriented transects radiating outward from vestimentiferan thickets to evaluate changes in macrofaunal community structure from thickets into the background community. Macrofaunal abundance was elevated at distances of 0–1 m compared to 80–200 m (i.e. the ‘background’ community). The tube‐building frenulate worms Siboglinum spp., along with peracarid crustaceans, dominated sediments within 1 m of vestimentiferan thickets. Species diversity was depressed within 1 m of thickets but with high rates of species accumulation, suggesting that seep sites greatly increase sediment heterogeneity and facilitate colonization by non‐background macrofaunal species. Stable isotope data indicate chemosynthetic nutrition for some dominant macrofaunal species within 1 m of tubeworm thickets. The macrofaunal community near vestimentiferan thickets in San Clemente seep contains intermediate levels of species richness and diversity compared to other deep‐sea seep areas in the northeast Pacific. There was low species overlap between the San Clemente seep macrofauna and communities in reducing habitats near wood‐, whale‐, and kelp‐falls at similar depths within the region, suggesting that seeps harbor a distinct infaunal community.     

Above and belowground phenology of four Mediterranean sub-shrubs. Preliminary results on root–shoot competition

Above and belowground phenology are critical aspects for plant life in areas of seasonal climate like Mediterranean regions. However, fine root growth phenology is rarely considered in most phenological studies. In this article we describe the above and belowground phenology of four species of Mediterranean sub-shrubs growing along a gradient of temperature and water availability, with special attention at the relationship between both processes. Observations were conducted monthly over a minimum of 12 months per species. Fine root growth varied significantly throughout the year, being higher in autumn than in spring and minimum in summer. In the species growing in cold areas, root growth was also reduced during winter. Shoot growth was maximum in spring for the four study species, buts its beginning was related to the site temperature, being earlier in those species growing in warmer sites. The species displaying a short vegetative period tended to separate root and shoot growth processes throughout the year. These results emphasize the importance of water availability and winter cold on fine root growth. A trade-off appears to exist between the duration of the vegetative period and the overlap between root and shoot growth processes.