山东省石灰岩山地的适生树种资源

本文简述了山东省石灰石岩山地的概况，列出了山东省石灰岩山地的适生树种名录，编制了分类检索表，提出了加速瘠薄山地绿化的建议和措施。     

上海市公园绿地树叶对大气重金属污染的磁学响应

为探究城市公园绿地树叶对大气重金属污染的磁学响应,按照上海市年均主导风设置纵横两个采样断面,采集城郊区公园绿地中广泛分布的香樟树叶,进行岩石磁学和重金属元素分析.结果表明,样品磁性矿物以亚铁磁性矿物为主导,磁性颗粒物的含量和粒径由典型工业区沿冬季风方向逐级递减.对叶片进行超声清洗后磁化率下降63%~90%,即样品的磁性特征主要取决于叶表附尘.树叶重金属元素Fe、Mn、Zn、Cu、Cr、V、Pb含量与磁参数显著相关(0.442≤R≤0.799,P0.05),说明城市公园绿地树叶磁参数可以作为大气重金属污染的替代指标.运用多元统计分析方法表明,研究区树叶磁性矿物及重金属含量主要受工业活动和交通道路污染的复合影响.     

立木地上部分生物量模型的建立及其应用研究

根据杉木、马尾松、阔叶树３个树种（组）的样本资料，研究提出了一套建立立木生物量模型及其在区域性森林生物量资源清查中应用的有效方法，解决了总量与各维量间相兼容和生物量估计与森林蓄积量清查的立木材积估计相兼容的问题，而且使模型的精度和适用性相对于传统的二元立木生物量模型有明显提高。     

滇西北地区高寒草甸多年生草本植物年轮特征分析

近年来的研究表明,年轮在多年生草本植物根部广泛分布,并且每年都会形成新的年轮。然而,目前对于滇西北高寒草甸草本植物年轮的存在及年轮特征的研究甚少,草本植物的年龄也基本未知。本文以滇西北高寒草甸的15种多年生草本植物为研究对象,分析了主根次生木质部的年轮特征,测量了年轮宽度及导管参数。结果表明：11种植物具有清晰的年轮结构,60%的植物具有清晰或相对清晰的年轮边界。这些草本植物的生长期是从2012到2017年,平均年龄为3.8岁（2—6岁）。该地区的物种生活史缩短的主要原因可能是高山林线以上的环境胁迫导致的。在草本植物生长前期,主营养生长,草本植物的径向生长与气候之间存在较为密切的关系,气候变化对高山草甸植被的影响直接作用于草本植物的生理生态过程中。高海拔地区光照充足,植物具有较强的光合作用,使得多年生草本植物的生长速率和导水效率随年龄增长呈上升趋势,这也可能是对全球变暖的积极反馈机制。随着年龄的增加,草本植物为增加生存和繁殖成功的机率,会采取一系列自我保护措施,改变生活史策略,减少导管数量,同时减小导管的大小。     

北京市大气污染动态变化的树木年轮分析

利用从香山、颐和园公园所取得的油松年轮中提取的年轮宽度和年轮木质部中化学元素含量变化的信息 ,主要分析了油松年轮中化学元素含量随时间变化的特点 ,结合北京市社会经济分析 ,揭示了元素含量变化的成因 ,并恢复了北京市近两百年大气污染的历史。     

一种基于可靠性理论的区域环境质量风险评价模型探讨

首先从理论上研究了用可靠性理论进行区域环境质量风险评价需要解决的几个基本问题,在此基础上,构建了环境污染故障树和区域环境质量风险评价的数学模型.这是一种以概率为基础的、新的区域环境质量风险评价模型,对于研究污染型工业系统的环境质量风险具有重要意义.     

Sensor design for saltwater ingress detection in high reliable all-electric deep sea actuators

Subsea oil and gas production relies on Xmas Trees which are mounted on boreholes. Xmas Trees are an arrangement of different valve types and sizes actuated by hydraulic, electro-mechanic or all-electric actuators. All these actuators sharing problems with saltwater ingress and the re-sulting increased wear. This paper investigates potential effects which can be measured after saltwater ingress. Extensive testing is executed and the investigated effects are used for novel sensor designs. These designs are evaluated regarding certain requirements and a resulting sen-sor design is proposed for industrialization. The resulting sensor can then be used to collect new important data to support optimal maintenance in the subsea industry.     

Age and spatial distribution of the world's oldest trees

Extremely old trees have important roles in providing insights about historical climatic events and supporting cultural values, yet there has been limited work on their global distribution and conservation. We extracted information on 197,855 tree cores from 4854 sites and combined it with other tree age (e.g., the OLDLIST) data from a further 156 sites to determine the age of the world's oldest trees and quantify the factors influencing their global distribution. We found that extremely old trees >1000 years were rare. Among 30 individual trees that exceeded 2000 years old, 27 occurred in high mountains. We modeled maximum tree age with climatic, soil topographic, and anthropogenic variables, and our regression models demonstrated that elevation, human population density, soil carbon content, and mean annual temperature were key determinants of the distribution of the world's oldest trees. Specifically, our model predicted that many of the oldest trees will occur in high-elevation, cold, and arid mountains with limited human disturbance. This pattern was markedly different from that of the tallest trees, which were more likely to occur in relatively more mesic and productive locations. Global warming and expansion of human activities may induce rapid population declines of extremely old trees. New strategies, including targeted establishment of conservation reserves in remote regions, especially those in western parts of China and the United States, are required to protect these trees.