Impacts of Alternative Timber Harvest Practices on Leaf-Chewing Herbivores of Oak

Abstract:  Studies of the effects of logging on Lepidoptera rarely address landscape-level effects or effects on larval, leaf-feeding stages. We examined the impacts of uneven-aged and even-aged logging on the abundance, richness, and community structure of leaf-chewing insects of white ( Quercus alba L.) and black ( Q. velutina L.) oak trees remaining in unharvested areas by sampling 3 years before and 7 years after harvest. After harvest, white oaks in uneven-aged sites had 32% fewer species of leaf-chewing insects than control sites. This reduction in species richness may have resulted from changes in microclimate (reducing plant quality and/or changing leaf phenology) that affected a much larger total area of each site than did even-aged cuts. For black oak after harvest, species richness in uneven- and even-aged sites increased relative to levels before harvest. Harvesting did not alter total insect density or community structure in the unlogged habitat for either oak species with one exception: insect density on black oak increased in the oldest forest block. Community structure of herbivores of black and white oaks in clearcut gaps differed from that of oaks in intact areas of even-aged sites. Furthermore, both richness and total insect density of black oaks were reduced in clearcut gaps. We suggest that low-level harvests alter herbivore species richness at the landscape level. Treatment effects were subtle because we sampled untreated areas of logged landscapes, only one harvest had occurred, and large temporal and spatial variation in abundance and richness existed. Although the effects of logging were greater in uneven-aged sites, the effects of even-aged management are likely to increase as harvesting continues.     

Recent Evolution of Petroleum Exploration and Exploitation Agreements in Developing Countries: New Approaches to Introduce More Flexibility and Progressivity in the Contractual Terms

Over the last decade rather important changes have occurred in the legal and economic aspects of international petroleum agreements for exploration and exploitation. In the late nineteen seventies, as a consequence of the strong increase in oil prices, there was a general tightening of contractual terms and conditions. With the present oil market imbalance, characterized by sharp price falls, there is a tendency to ease the applicable contractual terms. In such a rapidly changing environment, the economic terms contained in a petroleum agreement should be properly designed to introduce a certain element of flexibility and progressivity in regard to the government take, without unduly complicating the fiscal package or discouraging potential investors. This is the present challenge for international petroleum negotiators.     

非耐短路变压器短路和过载保护试验的自动测试系统

针对变压器产品认证标准GB 19212.1(IEC 61558-1)中关于"短路和过载保护"的型式试验项目,研发了一套智能自动测试系统。对于两种类型的非耐短路变压器,即输入保护和输出保护类型,分别给出了系统软硬件配置和详细的测试操作流程。相比传统手动测试方式,该系统的应用可显著减少人员在线时间,同时降低人工测量环节的不确定度。     

MODELING NITROGEN UPTAKE AND POTENTIAL NITRATE LEACHING UNDER DIFFERENT IRRIGATION PROGRAMS IN NITROGEN-FERTILIZED TOMATO USING THE COMPUTER PROGRAM NLEAP

Readily available nitrogen (N) sources such as ammonium nitrate with excessive irrigation present a potential hazard for the environment. The computer program Nitrate Leaching and Economic Analysis Package (NLEAP) is a mechanistic model developed for rapid site-specific estimates of nitrate-nitrogen (NO₃-N) moving below the root zone in agricultural crops and potantial impacts of NO₃-N leaching into groundwater. In this study, the value of NLEAP was tested to simulate N uptake by crops and NO₃-N leaching parameters in large lysimeters under the tomato crop. Three seedlings of tomato variety of H-2274 (Lycopersicum esculentum L.) were transplanted into each lysimeter. N fertilizer at the rate of 140 kg N ha^–1 was sidedressed in two split applications, the first half as ammonium sulphate and the second half as ammonium nitrate. The lysimeters were irrigated based on programs of C 0.75, 1.00, 1.25 and 1.50, C referring to class A-Pan evaporation coefficients. Parameters such as leaching index (LI), annual leaching risk potential (ALRP), N available for leaching (NAL), amount of NO₃-N leached (NL) and amount of N taken up by the crops (NU) were estimated using the NLEAP computer model. To test the ability of model to simulate N uptake and NL, measured values were compared with simulated values. Significant correlations, R² = 0.92 and P < 0.03 for the first year and R² = 0.86 and P < 0.06 for the second year, were found between measured and simulated values for crop N consumption, indicating that the NLEAP model adequately described crop N uptake under the varied irrigation programs using an optimal N fertilization program for the experimental site. Significant correlations, R² = 0.96 and P < 0.01 for the first year and R² = 0.97 and P < 0.01 for the second year, were also found between measured and simulated values of NL, indicating that the NLEAP model also adequately predicted NL under the varied irrigation programs. Therefore, this computer model can be useful to estimate the NO₃-N moving beyond the root zone under conditions in which the present experiment was carried out. Also, the NLEAP-estimated NAL values and other parameters can also be used to improve N management practices and N fertilizer recommendations that will help to decrease the adverse effect of N fertilizer on groundwater quality and farm profitability.     

城市可持续发展评价的分指数及综合指数公式

在指标按特征分类的基础上，提出了城市可持续发展评价分类指标的分指数公式和多类别组合的综合指数公式。应用遗传算法对公式中的参数进行优化，得到简单而适用的城市可持续发展评价模型。模型应用于全国“七五”，“八五”可持续发展评价结果与实际分析结果一致。该模型具有可比性强，通用性好和简单，实用的特点。     

16S rRNA基因技术在环境科学领域中的应用

随着分子生物学的发展，16S rRNA基因技术被逐渐应用到环境科学领域中。目前在环境保护和治理中，该技术主要被用于鉴定污染物的生物降解菌和分析环境样品中的微生物群落多样性，由于它不必将微生物培养分离出来，也就避免了在培养过程中可能出现的微生物去失的情况。本文对16S rRNA基因技术及其在环境科学领域中的应用现状和发展作了一简要介绍，并对16S rRNA基因技术存在的不足进行了讨论。     

三峡库区万州塘角1号滑坡滑带特征研究

三峡库区顺坡向缓倾角滑坡灾害频发,万州塘角1号滑坡具有该种滑坡的典型特征。在对该滑坡详细调查研究、GPS观测及深部位移监测数据分析的基础上,通过钻探工程,探井开挖及大型现场剪切试验对该滑坡的滑带特征及力学性质进行了综合分析。研究结果表明:滑坡体表现为持续蠕滑,前缘比中部和后缘变形要大,其方向为NNW向,滑带埋深在10～21m,滑面呈波状起伏。探井揭露滑体中碎块石排布具有定向性和分段性特点,该滑坡存在多层次级滑动,认为在5.0～8.0m范围内存在一规模较大连续性较差的次级滑动带,受主滑带控制。滑坡各区的力学强度表现为不均一性,在滑坡前缘滑带土剪切强度比中部大,这主要是因为在中部地下水相比前缘要丰富,加上滑带土主要为粘土矿物,遇水膨胀软化致使强度降低。     

滴水湖水系表层沉积物中多氯联苯残留与风险评价

于2012年,每2个月采集一次上海人工滩涂湖泊——滴水湖水系表层沉积物,对其多氯联苯(PCBs)的残留水平进行了检测和分析.结果表明,研究期间闸外引水河和闸内引水河沉积物中7种PCBs的总量各月间变化较大,且总体呈上升趋势,而滴水湖沉积物中其总量四季变化幅度不大;空间分布上,闸外引水河[(844.74±687.62)ng/g]>闸内引水河[(516.83±645.45)ng/g]>>滴水湖[(81.63±72.18)ng/g].研究区PCBs组成以六氯联苯和七氯联苯为主,其次为五氯联苯和三氯联苯.采用主成分分析法对PCBs进行源解析,结果显示:PCBs污染源中进口电容器中PCBs的迁移占43%,油漆添加剂污染占33%;国产电容器和变压器污染占11%.生态风险评估表明,闸外引水河和闸内引水河沉积物PCBs对生物体的暴露有严重威胁;滴水湖沉积物PCBs对生物体的暴露有一定的潜在威胁.与国内外研究相比,闸外引水河和闸内引水河属于严重污染水平,滴水湖属于中等污染水平,相关部门应加强污染监管.     

HPLC-DRC-ICP-MS检测四种尿砷化合物

拟建立检测尿液中As(Ⅲ)、DMA(Ⅴ)、MMA(Ⅴ)和As(Ⅴ)4种砷化合物形态的HPLC-DRC-ICP-MS的方法。采用DRCTM(反应气为O2)与HPLC联用作为检测器,Phenomenex ODS-3作为分离柱,5 mmol/L四丁基羟胺,3 mmol/L丙二酸,5%(体积分数)甲醇为流动相(pH=5.0~6.0),建立了同时分析尿液中As(Ⅲ)、DMA(Ⅴ)、MMA(Ⅴ)和As(Ⅴ)的方法。实验结果显示:该分析方法对上述4种砷化合物的检测限均在0.1μg/L以下,在1~20μg/L范围内线性关系良好,准确度和精密度良好,回收率为89%~106%,样品中的Cl-1对测定没有影响。所建立的HPLC-DRC-ICP-MS分析方法稳定、可靠,适用于快速、批量测定尿砷形态。