Effects of biodiversity on the functioning of trophic groups and ecosystems

Over the past decade, accelerating rates of species extinction have prompted an increasing number of studies to reduce species diversity experimentally and examine how this alters the efficiency by which communities capture resources and convert those into biomass. So far, the generality of patterns and processes observed in individual studies have been the subjects of considerable debate. Here we present a formal meta-analysis of studies that have experimentally manipulated species diversity to examine how it affects the functioning of numerous trophic groups in multiple types of ecosystem. We show that the average effect of decreasing species richness is to decrease the abundance or biomass of the focal trophic group, leading to less complete depletion of resources used by that group. At the same time, analyses reveal that the standing stock of, and resource depletion by, the most species-rich polyculture tends to be no different from that of the single most productive species used in an experiment. Of the known mechanisms that might explain these trends, results are most consistent with what is called the 'sampling effect', which occurs when diverse communities are more likely to contain and become dominated by the most productive species. Whether this mechanism is widespread in natural communities is currently controversial. Patterns we report are remarkably consistent for four different trophic groups (producers, herbivores, detritivores and predators) and two major ecosystem types (aquatic and terrestrial). Collectively, our analyses suggest that the average species loss does indeed affect the functioning of a wide variety of organisms and ecosystems, but the magnitude of these effects is ultimately determined by the identity of species that are going extinct.     

Approaches to prediction of impact of Qinghai-Tibet Railway construction on alpine ecosystems alongside and its recovery

With the aid of the Remote Sensing (RS) and Geographic Information System (GIS) technology, the ecosystem pattern and fragility distribution maps of the 50-km-wide zone along the Qinghai-Tibet Railway were compiled and by using the superimposition method, range, area and indexes of the impact of various engineering activities on the ecosystems alongside the railway were studied. By making reference to the ecosystem recovery process of the Qinghai-Tibet Highway, mechanisms of recovery of the alpine ecosystems alongside the Qinghai-Tibet Railway were studied and extents and rates of the recovery were predicted.The results indicate that the impact of the railway engineering on the Alpine ecosystem depends mainly on how much the original surface soil in the zone has been disturbed and how fragile of the ecosystem per se. Restoration of vegetation coverage and species abundance shows a significantly reverse relationship with disturbance of the original surface soil but an extremely positive one with the length of the restoration period and mean annual precipitation and annual mean relative humidity in the period and no obvious bearings with altitude and temperature. In sections with an annual precipitation over 200mm, as long as a certain percentage of original soil is left in situ, it takes only 30 years or so for biodiversity to get basically restored to the original level after the construction is completed but at least 45-60 years or more for vegetation coverage.     

施用沼液对农林土壤生态系统影响的研究进展

目前,沼液排放量逐年增加,对农林土壤的影响也在增大,笔者就施用沼液对土壤的影响研究现状进行了综合分析,总结归纳施用沼液对农林土壤理化与生物学特性的影响及其机制。认为:①适当沼液施用条件下农林土壤动物、微生物的数量,全氮、全钾、全磷、速效氮、速效磷和速效钾的含量都有所提高; ②土壤的理化性质和结构及施用沼液的质量浓度、用量、使用时间都是影响农林土壤生态系统的重要因素; ③施用沼液可能增加土壤重金属含量,不同土层各种重金属含量增加程度不一; ④不同的沼液处理方式、发酵时间,对农林土壤的重金属积累、土壤动物的影响各异,稀释后的沼液比原沼液灌溉土壤更易造成Cd、Cu的积累,新鲜沼液比陈放沼液对土壤动物的抑制作用更明显。因此,施用沼液是资源可持续循环利用的重要途径之一,合理施用沼液不仅可以提高农林土壤生产力,也可以保护生态环境; 同时,因土壤生物学特性、理化性质等不同,长期施用沼液对不同类型农林土壤的影响结果有所不同,尤其对土壤生态系统的生物学与生态学的过程与机制尚不清楚。在研究施用沼液对农林土壤的影响及其响应机制过程中,一方面要做2 a甚至更长时间的定位观测与分析; 另一方面要考虑不同处理沼液的理化性质以及实验土壤的理化和生物学特性的差异,深入探究沼液内含物在土壤中的迁移、转化过程以及吸附作用,以达到长期维持土壤生产力的目的。     

深海采矿矿浆泵的设计方法研究

针对深海采矿矿浆泵尚无成熟的设计方法,基于垂直管道水力输送理论,文章提出了矿浆泵设计参数的理论公式,并对不同工作水深及矿石体积分数下的输送系统进行了分析;采用数值模拟方法分析了几何参数对泵性能的影响。分析结果表明:将体积分数为5%~10%的多金属结核从1 000m和6 000m海底提升至海面所需泵的扬程分别为78.04~130.05m和440.63~735.17m,考虑装备制造的技术能力,矿石体积分数宜控制在8%以下;叶轮叶片数推荐值为4~5,以满足扬程和效率的要求;适当增大叶片进口角可改善泵的抗气蚀性能。最后,通过试验验证了数值分析方法的准确性。     

集合种群受生境破坏影响的新模型及其生态效应研究

从两物种竞争模型出发,提出了集合种群上3物种的食物网机制,构造了一个捕食者和两个猎物(似然竞争)受生境破坏影响的新模型;基于微分动力系统的数值模拟和网格模型的元胞自动机模拟,研究了生境破坏对集合种群动态的影响.结果发现:集合种群似然竞争模型系统对生境破坏非常敏感,生境破坏导致了更不稳定的动态,而且发现具有较小捕食者侵占率的猎物受生境破坏影响较大,进而表明了猎物对捕食者的敏感度与受生境破坏的影响之间存在负藕联关系;适当的生境破坏有利于劣势物种的生存;捕食者通过猎物受到生境破坏的间接影响,而且在生境破坏生态过程中捕食者是脆弱的.该研究结果为物种续存和生物多样性保护提供了理论依据.     

Annihilation of ecosystems by large asteroid impacts on the early Earth

Large asteroid impacts produced globally lethal conditions by evaporating large volumes of ocean water on the early Earth. The Earth may have been continuously habitable by ecosystems that did not depend on photosynthesis as early as 4.44 Gyr BP (before present). Only a brief interval after 3.8 Gyr exists between the time when obligate photosynthetic organisms could continuously evolve and the time when the palaeontological record indicates highly evolved photosynthetic ecosystems.     

Effect of microbes on karstification in karst ecosystems

The role of microbes in the karstification process was determined based on the karst dynamics,CO2 capture,and carbonate deposition.A close relationship was found among microbial activity,karst dynamics and stability,and the carbon cycle in a karst ecosystem.More in-depth studies were needed to investigate the impact of microbes on karst dynamics within different eco-envi-ronments under natural conditions to determine the response of biological organisms to a changing environment,as well as the relationship between microbial organisms and the karstification process.     

葫芦岛底栖海藻的季节性变化规律

报导了葫芦岛底栖海藻的组成,区系性质、群落的结构和季节性变化．经调查该海区隶属于红藻门、褐藻门和绿藻门的底栖海藻共有103种,其中包括50种经济海藻．研究表明,葫芦岛底栖海藻的温度性质以暖温带性为主,带有一定的亚热带性,其群落组成的季节性变化非常明显．     

森林生态系统不同碳库碳储量估算方法的评价

森林在降低大气CO2含量和减缓全球气候变暖趋势方面起着非常重要的作用。估算森林的碳储量以及分析和评价森林不同碳库的组成和动态变化已成为目前生态学关注的热点之一。由于使用方法和途径的不同,导致对森林碳储量和不同碳库大小的估算结果出现很大的差异,由此,笔者对森林生态系统中不同碳库的估算方法进行了分析和综述,总结了不同估算方法的优缺点及其适用范围。     

甘肃省高速公路生态环境的可持续发展评价

运用层次分析和神经网络相结合的综合评价方法,从静态和动态2个方面对甘肃省内5条高速公路的可持续发展作了综合的实证分析研究.分析结果表明,5条高等级公路生态环境可持续发展趋势度值随着时间变化呈上升趋势,说明5条高等级公路生态环境在发展水平和发展协调度2方面均有较好的可持续发展态势.     

气候变化对森林生态系统的主要影响述评

森林生态系统是陆地生态系统的主体,其对减少大气中的CO₂浓度从而减缓全球变暖有着决定性的作用。为了探究气候变化对森林生态系统的影响以及森林生态系统的反馈机制,发展合理的森林经营策略以应对气候变化,笔者综述了国内外有关气候变化对森林生态系统影响的相关研究方法与成果,重点讨论了气候变化对森林结构、组成和分布、森林生产力、森林碳库、森林生态系统生物多样性、生态系统生态服务功能等方面的影响,论述了森林生态系统对气候变化的反馈机制,并指出了现有研究的不足之处,提出了适应或者减缓气候变化对森林生态系统影响的森林经营策略,主要包括:①坚决贯彻实施退耕还林政策; ②加强保护天然林; ③制定科学的森林经营对策; ④加速我国碳汇林业的发展。     

深海压力传感器的结构设计及力学特性研究

基于油液的可压缩性,将活塞式压力平衡装置与敏感膜片组合起来,设计了一种深海活塞式压力传感器,通过设置活塞式压力平衡装置使传感器能承受大压力,利用油液压缩体积与压力之间的关系来测量大压力,采用敏感膜片来测量水压的微小变化量,既能承受深海大压力又能实现高精度测量.阐述了其工作原理及结构特点,并对其进行动态分析,研究结果表明:敏感膜片应采用橡胶膜片,压力传感器内外压差较小.     

基于Delphi的深海物探设备管理系统设计

在深海石油勘探船队的设备管理中,设备信息的及时交流和沟通成为影响船队正常生产的关键因素,在这其中,网络和计算机技术发挥了重要的作用。通过对船队设备管理流程的研究和分析,结合船队设备管理的实际操作,利用Delphi7和SQL Server 2000并采用了三层C/S结构设计一种深海作业船队设备管理系统。系统通过用户管理、设备管理、文件管理、供应商信息管理、维修商信息管理这五个管理模块,有效的解决了设备管理效率低下,实现了企业设备管理系统的简单化、规范化、合理化、科学化,改变了传统的纸笔以及windows office单机管理模式,很大程度上提高了企业设备管理、使用及维修的效率。     

SUDS水健康与底栖无脊椎动物的关系研究

对苏格兰邓佛姆林郡4个城市可持续排水系统(sustainable urban drainage system,SUDS)的理化指标及底栖无脊椎动物群落结构的时空变化特征进行了分析.结果表明:底栖无脊椎动物的丰富度及敏感种比重为人工湿地＞3号滞留池＞2号滞留池＞1号滞留池,底栖无脊椎动物的丰富度与敏感种比重与环境要素显著相关,SUDS的深度、流域内透水斑块比重和污染物输入量对底栖动物群落结构及污染物的移除率有显著影响,随时间的延长,外来种逐渐替代了人工湿地的本地种.     

三江源不同生态系统下土壤微生物区系研究

研究了三江源国家保护区不同生态系统下土壤有机质及土壤微生物数量.结果表明:各生态系统土壤微生物数量、有机质均表现出差异,湿地生态系统土壤有机质、土壤微生物均高于其他生态系统.