Simulation of evapotranspiration and carbon dioxide flux in the wheat‐maize rotation croplands of the North China Plain using the Simple Biosphere Model

The North China Plain, which is critical for food production in China, is encountering serious water shortage due to heavy agricultural water requirement. The accurate modelling of carbon dioxide flux and evapotranspiration (ET) in croplands is thus essential for yield prediction and water resources management. The land surface model is powerful in simulating energy and carbon dioxide fluxes between land and atmosphere. Some key processes in the Simple Biosphere Model (Version 2, SiB2) were parameterized based on the observations. The simulated fluxes were tested against the eddy covariance flux measurements over two typical winter wheat/maize double cropping fields. A simple diagnostic parameterisation of soil respiration, not included in SiB2, was added and calibrated using the observations to model the carbon budget. The Ball‐Berry stomatal conductance model was calibrated using observed leaf gas exchange rate, showing that the original SiB2 could significantly underpredict the ET in the wheat field. SiB2 significantly underpredicted soil resistance at the Weishan site, leading to overpredict the ET. Overall, there was a close agreement between the simulated and observed latent heat fluxes and net CO₂ exchange using the re‐parameterized SiB2. These findings are important when the model is used for the regional simulation in the North China Plain. Copyright © 2011 John Wiley & Sons, Ltd.     

知识经济条件下的高校图书馆文献信息服务

知识经济时代文献信息资源是知识创新的源泉，信息服务业成为知识经济的先导产业。以高校高科技产业为例，说明了高校图书馆要立足于知识经济社会，只有拓宽文献信息服务的内容，同时为教学、科研服务，发展高科技产业。并对知识经济时代的高校图书馆文献信息服务提出了一些建议。     

论中印两国间的服务贸易合作

分析了对中印两国间的服务贸易往来现状,阐述了中印两国服务贸易合作的有利因素和不利因素,并对两国服务贸易发展与合作提出了相应的政策建议。     

基于Servlet服务链的分布式Web GIS研究

本文从Servlet技术出发,探讨了Servlet技术在Web GIS服务器实现上的优势。针对目前分布式Web GIS中面临的数据和信息的分布存储、地理信息难以整合、多用户并发访问瓶颈等问题;探讨了通过构建Servlet服务链来实现分布式Web GIS的体系架构,基于Servlet服务链的分布式空间数据的调度与管理,Web GIS服务器端GIS Servlet服务链的构建。最后,通过实验验证了多Servlet服务链在Web GIS中分布数据处理,服务中多用户并发访问等方面的优势。     

“一带一路”区域可持续发展生态环境遥感监测

2013年9月和10月,习近平主席在出访中亚和东南亚国家期间,先后提出了共建"丝绸之路经济带"和"21世纪海上丝绸之路"(简称"一带一路")的重大倡议。要全面保护"一带一路"区域生态环境,实现2030年可持续发展目标,是一个具有挑战性的问题。遥感技术对生态环境监测与评价发挥着十分重要的作用。本研究利用多尺度、多源遥感数据,对2015年"一带一路"区域的生态环境状况进行监测和分析,旨在提供可持续发展目标生态环境遥感监测的本底。本文选取了几个重要的生态环境方面开展监测与分析,主要包括宏观生态系统结构和植被状况、太阳能资源分布、水资源平衡、主要生态环境限制因素对经济走廊建设的影响、主要城市生态环境质量等。监测区域覆盖亚洲、非洲、欧洲和大洋洲的陆上区域。研究结果为生态环境评价与保护提供了有效的决策依据,有助于"一带一路"建设积极推进。     

基于可见—近红外反射光谱的典型农田重金属污染风险分类研究

对于人为因素或自然因素造成的农田土壤重金属元素污染,需要进行大面积的土壤环境质量调查和分类管控,然而传统的采样测试方法存在工作量大、代价高等问题。可见—近红外（Vis-NIR）反射光谱是一种快速低成本获取土壤理化信息的手段。为研究Vis-NIR反射光谱预测模型划分土壤重金属污染风险类别的能力,文章以典型人为污染地区（浙江温岭）和典型地质高背景地区（广西横县）的390份农田土壤为样本,测定8种重金属元素（As、Cd、Cr、Cu、Hg、Ni、Pb和Zn）的含量和pH值,并测定土壤Vis-NIR光谱。使用偏最小二乘（PLS）和支持向量机（SVM）算法建立回归模型,对土壤重金属含量和pH值进行预测,并基于预测值进行土壤重金属污染风险分类。结果显示,温岭土壤主要污染元素Cd和Cu的光谱模型回归预测偏差（RPD）分别为1.23和1.19,预测机制与有机质有关。横县土壤主要污染元素As和Cd的RPD分别为1.98和1.93,预测机制与铁氧化物和粘土矿物有关。地质高背景土壤重金属与铁氧化物的正相关性普遍较强,使得光谱模型对重金属含量预测准确度较高。温岭和横县土壤pH值的光谱模型RPD分别为1.76和1.68。土壤重金属污染风险光谱分类的总体 准确度分别为75.0%~100%（温岭）和80.0%~100％（横县）。将Vis-NIR光谱与遥感技术相结合,对农田土壤重金属污染风险进行快速分类总体是可行的。     

1980—2017年祁连山水源涵养量时空变化特征

祁连山是中国西北地区十分重要的生态安全屏障,也是当地极为关键的水源涵养区。基于InVEST模型中的产水量模块,对祁连山水源涵养量和时空变化进行了分析并探讨其影响因素。结果表明：祁连山多年平均产水总量和水源涵养总量约为93.03×10⁸ m³和57.83×10⁸ m³。从时间变化来看,水源涵养量呈上升趋势,上升速率约为0.196 mm·a^-1;在空间上呈“东多西少”的分布格局,与年降水量的空间分布大致相同。不同土地利用类型下的水源涵养总量依次为：草地（31.87×10⁸ m³）>林地（16.71×10⁸ m³）>耕地（4.92×10⁸ m³）>其他用地（2.29×10⁸ m³）>建设用地（0.63×10⁸ m³）。降水量与水源涵养量在所有研究时段内均存在显著正相关性。不同时期土地利用类型的变化也会对水源涵养量产生重要影响,研究区草地面积变化对水源涵养量影响较大。根据建立的经验公式并参考已有研究成果,估算得出研究区多年冻土地下冰储量在550 km³以上,在全球气候变暖的背景下,消融趋势明显。研究可为祁连山水资源合理配置和生态系统保护提供参考。     

Silica biogeochemical cycle in temperate ecosystems of the Pampean Plain,Argentina

Silicophytoliths were produced in the plant communities of the Pampean Plain during the Quaternary. The biogeochemistry of silicon is scarcely known in continental environments of Argentina. The aim of this work is to present a synthesis of: the plant production and the presence of silicophytoliths in soils with grasses, and its relationship with silica content in soil solution, soil matrix and groundwaters in temperate ecosystems of the Pampean Plain, Argentina. We quantified the content of silicophytoliths in representative grasses and soils of the area. Mineralochemical determinations of the soils' matrix were made. The concentration of silica was determined in soil solution and groundwaters. The silicophytoliths assemblages in plants let to differenciate subfamilies within Poaceae. In soils, silicophytoliths represent 40–5% of the total components, conforming a stock of 59–72 × 10³ kg/ha in A horizons. The concentration of SiO₂ in soil solution increases with depth (453–1243 μmol/L) in relation with plant communities, their nutritional requirements and root development. The average concentration of silica in groundwaters is 840 umol/L. In the studied soils, inorganic minerals and volcanic shards show no features of weathering. About 10–40% of silicophytoliths were taxonomically unidentified because of their weathering degrees. The matrix of the aggregates is made up by microaggregates composed of carbon and silicon. The weathering of silicophytoliths is a process that contributes to the formation of amorphous silica-rich matrix of the aggregates. So, silicophytoliths could play an important role in the silica cycle being a sink and source of Si in soils and enriching soil solutions and groundwaters.     

生态模型在河口管理中的应用研究综述

河口作为河流和海洋的交汇地,具有生态交错带特性,其在自然和人类活动双重压力下发生着演变.生态模型是研究生态系统结构、功能及其时空演变规律以及生物过程对于生态系统的影响及其反馈机制的重要手段.采用不同方法对生态模型进行分类,综述各类生态模型的特性、优缺点及应用领域.讨论建模过程中模型变量与函数、模型整合及时空尺度、模型参数取值及不确定等关键技术问题.分析各类生态模型在河口生态工程设计、生态系统修复、生态系统评价、系统决策支持等管理领域的应用.尽管中国河口生态模型构建及应用已有一些成果,但与国外相比,在理论生态学及数据积累方面仍有一定差距.