南岭大顶山与鼎湖山常绿阔叶林种群分布格局对比研究

为了研究亚热带常绿阔叶林群落物种多样性的动态特征,在南岭大顶山和鼎湖山的常绿阔叶林各建立了1hm2永久样地。根据对样地植物物种多样性测定,研究了两地植物物种多样性的空间分布特征和多度分布特征。结果表明,位于南岭大顶山的常绿阔叶林群落较鼎湖山的季风常绿阔叶林具有更高的物种丰富度,但具有较少的胸径≥1cm的乔木个体。南岭大顶山的常绿阔叶林大多数优势种的种群为集中分布,鼎湖山的常绿阔叶林优势种的种群具有相对较多的规则分布。     

内蒙古中东部大针茅群落土壤线虫多样性研究

2003年在内蒙古西乌旗大针茅草原，根据土壤深度0～10cm、1020cm、20～30cm分层采样，定量分析土壤线虫群落的多度，并对土壤线虫群落多样性和群落内线虫营养类型进一步分析．结果表明，该群落中土壤线虫包括50属和24科，其中矮化属、拟盘旋属、丽突属为优势属，特别是矮化属线虫数量异常高．土壤线虫群落的垂直分布呈现表聚型．就功能类群而言，植食性线虫在各层中的比例最高，为69．4％～81．3％，食真菌类线虫的比例最低，为0．9％～2．4％，而食细菌类线虫比例为13．9％-20．9％，食真菌类线虫和食细菌类线虫的比值为0．067～0．133．表6参29     

洞庭湖湿地珍稀濒危鸟类群落组成及多样性

2005年7至2007年4月,采用直接记数法和"GPS"技术定位监测对洞庭湖湿地珍稀濒危保护鸟类资源及其环境进行调查。结果表明:洞庭湖湿地珍稀濒危保护鸟类有218种,隶属于16目46科。其中古北界鸟类占优势,有118种,东洋界鸟类54,广布种鸟类46种。冬候鸟为主体,有118种,留鸟40种,夏侯鸟35种,旅鸟25种。按生态类群分,游禽45种、涉禽69种、陆禽3种、猛禽22种、攀禽11种、鸣禽68种;该湿地有国家Ⅰ级重点保护鸟类7种、Ⅱ级重点保护鸟类43种,国际湿地公约名录中的鸟类37种。洞庭湖湿地珍稀濒危保护鸟类群落Shannon-Wiener多样性指数和Pielou均匀性指数分别为4.489 7和0.576 5。     

元江干热河谷植物群落特征及土壤肥力研究

对云南省元江县境内元江河谷山坡上的5种主要植被类型的群落特征、植物多样性现状、植物区系组成以及不同群落土壤理化性质进行了比较研究.结果表明:干热河谷区内,植物群落生活型组成主要以小乔木、灌木和草本植物为主,基本没有高大的乔木树种和大型藤本植物.草本植物生长旺盛,物种多样性和丰富度均较乔灌层高,但均匀度较其低.5种群落之间的相似性程度较低,且各群落均处于相对稳定的状态.各群落中共记录有61个科,144个属,194个物种,其植物区系的泛热带特征比较明显,其中泛热带分布科有31个,占除去广布科以外所有科的77.5%,泛热带分布属有50个,占除去广布属以外所有属的38.2%.蝶形花科Papilionaceae、禾本科Gramineae、大戟科Euphorbiaceae、菊科Compositae、锦葵科Malvaceae等科在元江干热河谷植被中占有极为重要的地位.群落土壤理化性质的研究表明,元江干热河谷各类植被的土壤元素中,除了磷元素极其缺乏以外,大多数处于中等以上水平.土壤肥力状况与植被的生长状况之间关系紧密,其中,土壤肥力最好的是群落结构比较复杂、残存的稀树旱生林.     

根瘤菌的遗传多样性与系统发育研究进展

根瘤菌 (ｒｈｉｚｏｂｉａ)是一类广泛分布于土壤中的革兰氏阴性细菌。它可以侵染豆科植物根部或茎部形成根瘤和少数茎瘤 ,固定空气中的分子态氮形成氨 ,为植物提供氮素营养 .据估计 ,全球每年生物固氮量达 1.75× 10 8ｔ,为世界工业氮肥产量的4 .37倍[1] .根瘤菌与豆科植物的共生固氮作用是生物固氮中固氮效率最高的体系 .因此 ,根瘤菌与豆科植物的共生固氮作用是实现农业可持续发展的重大研究课题之一 .研究根瘤菌的遗传多样性 ,对于发掘新的根瘤菌种质资源 ,保藏并合理利用根瘤菌基因资源库 ,选育高效菌株直接应用于农业生产有重要意义 .…     

Residential Radon in U.S. Counties V Lung Cancer in Women Who Predominantly Never Smoked

Previous studies have found that mean-residential-radon (Rn) levels for U.S. counties are negatively associated with age-adjusted county rates of lung-cancer mortality (LCM), after adjustments for potentially confounding factors. Those results may be due to (a) confounding unaddressable by any county-level (ecological) study design, or (b) county-level factors such as Rn/smoking or age/radon correlations or exposure misclassifications from the use of disparate data sources. Possibilities (b) were addressed by comparing age-specific LCM rates for white women in 2821 U.S. counties who died in 1950–54 at age 40+ (11% of whom ever smoked), or at age 60+ (% of whom ever smoked), to county Rn levels newly estimated from U.S. Rn, climatic and geological-survey data. Significant negative LCM v Rn trends were found for both age groups, after adjusting for age and subsets of 21 county-level socioeconomic, climatic and other factors. Negative trends were largest for counties with 100 Bq m^–3 Rn (p 0.00087; 420 analyses). Adjusted relative risk (RR_adj) for LCM was significantly elevated (1 < [95% conf. limits on RR_adj] 1.46) in 43 of 210 analyses comparing LCM rates in counties with > 150 Bq m^–3 v 65–100 Bq m^–3 Rn, most involving adjustment for climate- and education-related factors likely to have influenced exposure to indoor air contaminants such as Rn and cigarette smoke. Though inconclusive due to potential ecological-fallacy-related confounding that could not be controlled, results from this ecological study are most consistent with a U-shaped dose-response relationship between 1950–54 LCM risk and U.S. residential radon in white women who predominantly never smoked.     

Zooplankton proportion estimates from non-uniform sample volumes

The relative abundance of organisms from different taxa provides information about ecosystem health and diversity. When the numbers of sampled organisms are modelled as Poisson counts, and the sample volumes are not uniform, variance for the proportion attributable to each taxon is difficult to compute. We present a method for computing approximate variances for this situation. The point estimates and their standard errors reduce to the standard multinomial maximum likelihood results when sample volumes are uniform. Further, given initial estimates of population densities for the taxa of interest, optimal sample volumes can be computed. The methods are illustrated for zooplankton counts from Andrus Lake, Michigan.     

醌类图谱分析在环境微生物生态测定中的应用

近年来，随着人们对各种非培养微生物测定法的重视，醌类图谱分析作为微生物群体指标已在各种环境中得到了应用．首先是样品的分析测定技术得到了提高，如用硅胶柱代替薄层色谱．醌类图谱分析的特点是能够同时对应微生物生态评价的3个重要指标，即微生物群体结构、生物量及微生物多样性．在结合统计分析的基础上，在土壤、污泥及堆肥等不同环境样品及不同微生物反应过程中，已通过醌类图谱分析对这3个指标在微生物生态系中的变动进行了成功的评价．另外，对C-14同位素标记醌类图谱分析法及醌类图谱分析法在污染物降解中的应用等最新进展也进行了简介．图4表3参43     

Variations of plant life form diversity along northeast China transect and its direct gradient analysis

Plant life form diversity and its direct gradientanalysis on a larger scale climate change gradient were tested,based on the data from Northeast China transect platform. Theresults showed that the species numbers, life form richness andlife form diversity were relative higher at the eastern forests andthe ecotone between typical vegetation, while those on the meadowgrasslands and typical steppes were lower. Although plant lifeforms can reflect the climate variations, life form diversity isnot consistent with the major global gradient along the NECT.     

Portfolio-Based Electricity Generation Planning: Policy Implications For Renewables And Energy Security

Renewable generating technologies offer an effective means for climate change mitigation. Policy makers, however, are wary because of the widespread perception that these technologies cost more than conventional alternatives so that increasing their deployment will raise overall electricity generating costs. Energy planning represents an investment-decision problem. Investors commonly evaluate such problems using portfolio theory to manage risk and maximize portfolio performance under a variety of unpredictable economic outcomes. Energy planners need to similarly abandon their reliance on traditional, “least-cost” stand-alone kWh generating cost measures and instead evaluate conventional and renewable energy sources on the basis of their portfolio cost – their cost contribution relative to their risk contribution to a mix of generating assets. Energy security generally focuses on the threat of abrupt supply disruptions. This paper suggests a more profound aspect: mitigating fossil price volatility. An extensive body of research indicates that fossil volatility significantly disrupts the economies of consuming nations, potentially exacting hundreds of billions of dollars from the US and EU economies alone. Energy security is reduced when countries hold inefficient portfolios that are needlessly exposed to fossil price risks. This paper describes essential portfolio-theory ideas and uses three case studies to illustrate how electricity-generating mixes can benefit from additional shares of wind, geothermal and other renewables. Compared to existing, fossil-dominated mixes, efficient portfolios reduce generating cost while including greater renewables shares in the mix thereby enhancing energy security. Though counter-intuitive, the idea that adding more costly renewables can actually reduce portfolio-generating cost is consistent with basic finance theory. An important implication is that in dynamic and uncertain environments, the relative value of generating technologies must be determined not by evaluating alternative resources, but by evaluating alternative resource portfolios.