Nematode diversity,food web condition,and chemical and physical properties in different soil habitats of an organic farm

The aim of this paper was to assess biodiversity among different habitats of an organic farm and the relationships between some soil properties, nematode taxonomic diversity, and soil food web condition. Eight habitats were studied in the farm: ponds, ditches, a riparian corridor, hedgerows, and four agricultural fields (mustard, oats, fallow, and legumes). The undisturbed riparian corridor had higher soil and concentrations, and potentially mineralizable N and higher abundances of bacterivore nematodes and longer food webs. Canonical correlation analysis showed associations between habitats and nematode trophic groups: predatory and bacterial-feeding nematodes in the riparian corridor and hedgerows, omnivore nematodes in the ponds and ditches, and fungal-feeding nematodes in the legume field. Soil chemical and physical properties mirrored the aboveground farm patterns and were more similar among habitats that were or had been cultivated, compared to the riparian corridor. Soil food web indices, based on functional analysis of nematode faunal composition, reflected the aboveground landscape heterogeneity. Discriminant analysis indicated that soil food web indices separated the two most disturbed habitats (ponds and tailwater ditches) from the two least disturbed habitats (the riparian corridor and hedgerows). The indices correlated with soil functioning as inferred by soil properties. Abundance of nematode taxa was not associated with aboveground landscape patterns. The complexity of the soil food web may have been influenced by (1) environmental factors that differed between years, (2) different time periods since disturbance in the various habitats, and (3) movement of nutrients and organisms by water flow between habitats in the farmscale.     

多尺度空间信息服务技术及其农业应用

从省市县三级空间尺度和应用特征的区域信息服务出发,研究基于网络的多源多尺度农业空间信息共享与服务技术.集成应用空间信息技术与Web服务技术,开展多源多尺度的农业空间信息资源的数据整合、统一业务模型构造、信息交换与共享、元数据目录服务等关键技术研究,建成多尺度的基础信息数据库群,开发实现了省级区域多源多尺度应用的空间信息服务平台.有效整合多源多尺度的农业信息资源,促进了区域空间信息应用与服务.     

基于Web的煤矿废弃地土地复垦决策支持系统设计与实现

为了克服现有煤矿废弃地土地复垦与植被恢复试验法费时费力的缺陷,根据土壤基质和气候相似性原理,采用模糊综合评价一灰色关联优势分析、基于距离的相似算法、基于规则的推理等多种数学方法,分别从植被恢复潜力评价、适生植物品种选择、土地复垦方案选择3个方面建立了相关数学模型,解决了煤矿废弃地恢复潜力的分级、先锋植物选种和土地复垦方案的确定等问题,从而为煤矿废弃地的植被恢复提供了一系列的决策支持.并使用ASENET 等编程语言结合MS Access数据库设计并开发了基于web的煤矿废弃地植被恢复的决策支持系统,该系统能为煤矿废弃地植被恢复工作提供新的研究模式和手段,并已经在辽宁省阜新矿区得到应用,结果表明系统所采用的方法科学、合理、可行.     

The Management Techniques of Distance Education and Its Implementation

The education modes and contents involved in the management of distance education are first analyzed in the paper, and the preliminary implementation based on CERNET and Internet is followed. The techniques of WWW servers efficient access to database and system security are presented in addition.     

农业网络资源的收集

本文阐述了网络信息资源的收集———一个信息增值的过程。分别论述了收集原则、信息的存在方式与收集方式,并介绍了应用数据挖掘技术,建立农业数据模型等方面的内容。     

Effect of Geogenic Lead on Fungal and Collembolan Communities in Garden Topsoil

Geogenic lead (Pb) is considered to be less bioavailable than anthropogenic Pb and exerts less effect on the soil fauna. However, Pb contamination in vegetables has been reported in the case of geogenic anomalies, even at moderate concentrations (around 170 mg kg^–1). In this study, we investigated collembolan communities using both taxonomic- and trait-based approaches and observed fungal communities to assess the effects of a moderate geogenic Pb anomaly on collembolans and fungi in an urban vegetable garden soil. Results indicated that geogenic Pb indeed modified fungi communities and altered the functional structure of collembolan communities in garden soils. Although geogenic Pb presented low bioavailability, it affected soil fauna and vegetables similar to anthropogenic Pb.     

Trophic pathways supporting Arctic grayling in a small stream on the Arctic Coastal Plain,Alaska

Beaded streams are prominent across the Arctic Coastal Plain (ACP) of Alaska, yet prey flow and food web dynamics supporting fish inhabiting these streams are poorly understood. Arctic grayling (Thymallus arcticus) are a widely distributed upper‐level consumer on the ACP and migrate into beaded streams to forage during the short 3‐month open‐water season. We investigated energy pathways and key prey resources that support grayling in a representative beaded stream, Crea Creek. We measured terrestrial invertebrates entering the stream from predominant riparian vegetation types, prey types supporting a range of fish size classes, and how riparian plants and fish size influenced foraging habits. We found that riparian plants influenced the quantity of terrestrial invertebrates entering Crea Creek; however, these differences were not reflected in fish diets. Prey type and size ingested varied with grayling size and season. Small grayling (<15 cm fork length (FL)) consumed mostly aquatic invertebrates early in the summer, and terrestrial invertebrates later in summer, while larger fish (>15 cm FL) foraged most heavily on ninespine stickleback (Pungitius pungitius) throughout the summer, indicating that grayling can be insectivorous and piscivorous, depending on size. These findings underscore the potential importance of small streams in Arctic ecosystems as key summer foraging habitats for fish. Understanding trophic pathways supporting stream fishes in these systems will help interpret whether and how petroleum development and climate change may affect energy flow and stream productivity, terrestrial–aquatic linkages and fishes in Arctic ecosystems.     

基于本体的农作物种质资源数据集成研究

随着国家农作物种质资源平台服务的进一步加强,平台数据与其他相关数据源的集成共享,成为当前迫切需要解决的问题。提出了元数据和两级本体相结合的语义元数据集成解决方案:首先建立农作物种质资源全局本体;然后抽取各分布数据库的元数据,按照统一标准集成到一个元数据库中,同时,依据不同数据源建立各局部本体;最后建立全局本体和元数据库的映射、局部本体和各数据源的映射,形成语义元数据。构建了农作物种质资源集成框架,并进行了集成系统设计。实验结果表明:该语义元数据方案能解决数据的语义描述和语义异构问题,可最终实现系统的集成;局部本体使得查询更具智能性,可提高查全、查准率,有利于提高服务质量。     

基于响应式Web的农业网站设计方法研究

响应式Web由于其适应全设备的特点,已成为当今网站设计的主流。该研究从对响应式Web的介绍和关键技术的分析入手,结合国内外响应式Web应用的现状,提出了农业网站响应式Web的设计流程,并对页面布局作出了多种方案分析,为农业网站建设提供参考。     

1959–2011年莱州湾渔业资源群落食物网结构的年间变化

通过对1959–-2011年莱州湾渔业资源摄食习性、营养级的分析, 构建了莱州湾生态系统简化食物网。结果表明, 莱州湾渔业资源群落食物网经历了“以鱼食性种类为主的食物网—以浮游动物食性种类为主的食物网—以浮游动物食性种类和底栖动物食性种类为主, 但浮游动物食性种类占比大于底栖动物食性种类的食物网—以浮游动物食性种类和底栖动物食性种类为主, 但底栖动物食性种类占比大于浮游动物食性种类的食物网—以底栖生物食性种类为主的食物网” 5个阶段的演变过程。中低营养阶层生物替代高营养阶层生物成为莱州湾生态系统食物网的顶级捕食者, 食物链越来越短, 食物网通过碎屑食物链传递的能量成为食物网能流的主体。在1959–-2011年期, 莱州湾渔业资源群落平均营养级从4.4下降到3.4, 平均以每10年0.19的速度下降, 高于整个渤海生态系统的下降速度; 种类组成的变化、个体小型化, 以及摄食食物种类的变化是引起莱州湾生态系统营养级波动的主要原因。