水土保持监测系统信息平台元数据的实现

参考当前元数据技术及相关标准，探讨了官厅密云水库上游水土保持监测系统信息平台建设中。元数据的构建与实现。首先针对应用系统建设的实际需求，明确了信息平台建设所包括的元数据内容：基础元数据与业务元数据，并描述了两者内容及其应用目标；其次在数据库技术支持下说明了元数据组织存储模式、结构关系等；最后说明了元数据的实现方式，并提出了元数据与数据同步、一体化管理，在信息平台数据更新维护的基础上实现了元数据的同步更新，从而集数据库及其元数据的更新维护于一体，实现了信息平台的有机构成。     

基于元数据的农田信息存储、管理和共享

为实现基于元数据的农田信息的存储、管理和共享,在建立农田信息数据元的基础上,采用空间数据库技术,构建了农田信息的分级存储与管理模型;利用元数据服务和组件技术,在SuperMap GIS平台上构建了农田信息共享服务与互操作模型。通过对“基于WebGIS的小麦生产精准施肥决策系统”和“基于GIS的河南省作物生产潜力评价系统”数据元的提取和封装,实现了两个系统数据的无损共享,结果表明,在建立农田信息标准元数据的基础上,利用元数据和元数据服务技术来解决农田信息一体化存储、管理和共享是可行和有效的。     

农业数据网格体系研究

由于农业数据具有地理分布、异构和动态等特性，网络环境下农业数据的分发组织和高效能处理是一个非常复杂且具有挑战性的问题。该文设计了层次式的农业数据网格系统软件体系结构；研究了基于时空本体的农业元数据建模、农业数据空间聚类与映射、多系统信息协同和层次访问控制机制等关键技术；构建了农业数据网格节点应用环境。测试检验结果表明，所设计的农业数据网格体系具有良好的网络高性能传输能力。     

元数据与图书馆数字资源组织管理

元数据是数字图书馆建设的关键技术,也是数字图书馆进行知识组织和管理的工具。从元数据的定义、格式、编码语言、应用等方面入手,探讨了元数据在数字图书馆资源组织管理方面的规范,提出了元数据在数字图书馆建设中应注意的问题。     

黄河小流域监测评价元数据标准研究

元数据标准从应用角度可分为发布型和专题型两类。前者是关于数据的一般信息,后者指数据的专题信息。黄河小流域监测评价元数据标准研究以后者为核心,通过对有关数据资源的分析、解析和分类,建立了黄河小流域监测评价元数据标准体系,并对元数据组织管理、信息共享和专题应用模型研发进行了探讨。     

基于WebGIS的基本农田土壤环境质量评价系统

在区域土壤环境时空数据库支持下，以GeoWeb为地图服务器，利用ASP、JavaScript和HTML程序语言，建立基本农田土壤环境质量评价系统(PFSEGIS)，PFSEGIS的构建包括基本农田土壤环境数据库和模型系统两部分。数据库由样点监测数据、地形图数据和元数据组成。模型系统包含单因子评价模型、综合评价模型和空间插值模型。PFSEGIS包括样本数据采集、样本评价、区域模拟、信息统计、元数据浏览5个功能子系统，把监测数据与地图数据相结合进行空间分析处理，并通过模型运算，实现了基本农田土壤环境质量信息的在线共享、评价与咨询服务。     

无公害农产品认证资源共享的分布式元数据服务系统

为实现无公害农产品认证资源的利用共享化,该文以广域分散的无公害农产品数字化认证资源为研究对象,以实现资源访问透明性为目标,进行了认证资源元数据服务关键技术的研究。通过对认证资源的完备性与关联性特征分析,提出多层次认证资源集合模型,进行资源组织与划分;围绕认证资源和资源间关系的描述,进行元数据规范设计,提出认证资源元数据框架模型;围绕资源分布管理与服务支持,对认证资源层次结构与共享服务功能结构进行水平分割,分布部署在由中心域与资源域构成的共享服务网络中,构建了认证资源共享服务体系结构,并探讨了元数据请求与元数据分布存储的技术。研究结果表明,通过认证资源共享服务可将广域分散的资源集成为一个虚拟的认证资源库,为消费者、企业、职能技术部门和政府等服务对象提供资源统一的逻辑视图,实现资源访问的透明性,同时也可为认证工作由符合性评价向农产品质量安全市场监管进行转变提供技术支撑,具有较好的应用推广前景。     

基于Geodatabase数据模型设计实现水土保持规划数据库

概述了Geodatabase数据模型的结构和特点。针对水土保持规划数据库,采用面向对象的设计方法,利用UML和CASE工具,建立其地理数据模型。这种方法较传统方法直观、简便并且便于改动,是目前建立地理数据模型优先使用的方法之一。     

论数字黄土高原建设的若干问题

提出了“数字黄土高原”的概念,对其建设的必要性,发展的基础、目标、战略及其发展阶段,总体结构（包括数据组成、数据库结构、投影方式、数据层的组织）,和几个亟待研究的问题,包括数据标准与元数据体系、数据协调与集成方式、空间尺度的转换等,进行了初步的讨论。     

基于WebGIS的小麦精准施肥决策系统

为发展小麦精准施肥技术,在测土配方施肥技术基础上,利用Web Services、元数据、空间插值和AJAX技术,结合VS2005、ArcGIS 9.3和SQL Server 2005等软件,在.NET平台上构建了“基于WebGIS的小麦精准施肥决策系统”,系统采用4层架构设计,具有信息查询与定位、施肥决策、处方信息发布与共享等功能;系统定量计算了河南滑县22个乡镇的小麦精准施肥数据,实现了小麦处方信息的Web在线实时决策和发布,以及处方图的制作、生成和发布的半自动化。结果表明,基于元数据的处方图可以脱离GIS平台的限制,实现处方信息的多源和多系统自由共享。     

基于元数据仓储的数字资源管理探讨

以厦门大学图书馆为例,针对目前数字资源存在系统多样性、利用率较低、不易长期保存和不稳定等原因,厦门大学图书馆为数字资源建立了统一元数据仓储,并作为馆藏内容一部分。同时,厦门大学图书馆还在元数据仓储的基础上建立了统一检索应用平台,实现了数字资源统一检索,提高了数字资源的利用率和信息服务质量。     

建立水保基层单位规范化的数据文档文件和查询系统--以南安市水土保持试验站为例

建立统一的数据文档文件是实现数据资源共享的基础工程之一。以南安市水土保持站为例,详细地介绍了数据文档文件格式、数据编码,不同条件下的查询系统和数据的安全性。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.