Impact of elevated CO2 concentration under three soil water levels on growth of Cinnamomum camphora

Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture when the possible effects of elevated CO2 concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO2 concentrations （350 μmol/mol and 500μmnol/mol） and three soil moisture levels [80%, 60% and 40% FWC （field water capacity）] to focus on the effects of exposure of trees to elevated CO2 on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO2 concentration has no significant effects on shoot height but significantly impacts shoot weight and ratio of shoot weight to height under three soil moisture levels. The response of root growth to CO2 enrichment is just reversed, there are obvious effects on root length growth, but no effects on root weight growth and ratio of root weight to length. The CO2 enrichment decreased 20.42%, 32.78%, 20.59% of weight ratio of root to shoot under 40%, 60% and 80% FWC soil water conditions, respectively. And elevated CO2 concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO2 concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO2 enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO2 depend on soil water availability, and plants may benefit more from CO2 enrichment with sufficient water supply.     

Thermal conductivity of soils with heavy metals concentration from the Niger Delta region of Nigeria

INTRODUCTION Knowledge of soil thermal properties is an im- portant factor in understanding mass and energy ex- change processes in the soil-atmosphere system. The chemical composition of the soils will therefore in- directly relate to their thermal conductivities. Ac- cording to Usowicz (1993), this knowledge can also help in controlling the thermal-moisture regime of soils. Soil properties often correlated with metal ad- sorption include soil pH (Christensen, 1984; Harter, 1983), soil …     

为提高大众的科学素质而努力——《力学与实践》科普栏目的建设回顾

介绍在钱学森、周培源等著名力学家和广大力学工作者的关心和支持下,力学综合性期刊《力学与实践》科普特色栏目的建设历程。以创栏20周年的《身边力学的趣话》栏目为重点,回顾科普栏目建设的艰辛和成果,以及为贯彻国务院《全民科学素质行动计划纲要》所作的努力。     

静压桩沉桩挤土效应控制措施研究

静压桩在沉桩过程中会产生挤土效应,对周围环境造成不利影响。分析了挤土效应的具体表现,并且从设计和施工两个方面提出控制措施。在具体工程中可根据实际情况综合考虑,采取相应的合理控制措施。     

力学实验课教学改革的思考和实践

论述重新认识力学实验教学改革的必要性,结合教学实践,对力学实验课如何改革提出。一些设想并进行了实践.     

研究性学习在《工程力学》教学中的实施初探

结合工程力学教学,初步论述了研究性学习的定义、目标、特点以及实施的原则、类型、程序.     

工程流体力学的教学改革与应用

通过对工程流体力学的教学现状进行分析,从以工程案例为导向开展教学、注重开展实验教学活动、灵活采用丰富的教学方式、充分发挥在线教学平台的优势、建立起全面的成绩考核机制等方面,提出了推进工程流体力学教学改革的具体建议。     

聚焦东北黑土区农业生态 强化科技支撑国家粮食安全

“把黑土地用好养好”是新时代国家赋予东北地区新的使命和要求。围绕黑土退化和高产优质作物品种匮乏等制约东北农业发展的重要问题,中国科学院东北地理与农业生态研究所聚焦东北黑土区农业生态主责主业,紧扣黑土地保护与利用、东北主要作物种质资源创新、黑土区生态安全屏障等主要研究领域中的重大基础理论和关键核心技术问题开展原始创新,部署黑土地保护与利用、黑土区主要农作物种源创新与精准分子育种、湿地生态功能提升等重大任务,建立农业科学、湿地科学、地理信息科学与区域发展等学科紧密交叉与融合的创新体系,为保障国家粮食安全、生态环境建设和区域可持续发展提供理论基础和技术支撑。     

高职《建筑力学》教学探讨

《建筑力学》是建筑工程专业的一门重要专业基础课,教学成功与否,直接关系到后续的专业课程教学成效,影响学生对专业的学习兴趣。因此教师应抓起点严要求多鼓励,增强学习信心,并授之以渔,注重能力的培养。     

Improved yield and Zn accumulation for rice grain by Zn fertilization and optimized water management

研究目的：在生产高度集约化体系下,研究节水灌溉措施及锌肥对水稻产量及锌积累量的影响。创新要点：目前关于干湿交替能否对水稻增产仍存在争议,对锌含量及生物有效性也鲜有报道。因此,针对这些问题,本文系统地研究影响水稻产量及品质的两大限制性因素,即锌肥和灌溉方式对稻米锌生物有效性的影响。研究方法：采用盆钵试验模拟大田锌肥及水分管理方式,两种基因型、两种锌肥种类、两种水分管理,三个重复控制误差。利用电感耦合等离子体质谱（ICP-MS）测定微量元素锌含量,以精米中植酸含量表征锌生物有效性。重要结论：干湿交替在增加了稻米产量、锌含量及积累量方面效果显著。干湿交替结合土施硫酸锌肥可以作为水稻生产体系中获得高产、高锌、高生物有效性的农艺措施。