Demographic Stability Metrics for Conservation Prioritization of Isolated Populations

Abstract:  Systems of geographically isolated habitat patches house species that occur naturally as small, disjunct populations. Many of these species are of conservation concern, particularly under the interacting influences of isolation and rapid global change. One potential conservation strategy is to prioritize the populations most likely to persist through change and act as sources for future recolonization of less stable localities. We propose an approach to classify long-term population stability (and, presumably, future persistence potential) with composite demographic metrics derived from standard population-genetic data. Stability metrics can be related to simple habitat measures for a straightforward method of classifying localities to inform conservation management. We tested these ideas in a system of isolated desert headwater streams with mitochondrial sequence data from 16 populations of a flightless aquatic insect. Populations exhibited a wide range of stability scores, which were significantly predicted by dry-season aquatic habitat size. This preliminary test suggests strong potential for our proposed method of classifying isolated populations according to persistence potential. The approach is complementary to existing methods for prioritizing local habitats according to diversity patterns and should be tested further in other systems and with additional loci to inform composite demographic stability scores.     

湿法烟气脱硫吸收剂供应系统的应用分析与技术改进

作为湿法烟气脱硫的组成部分,吸收剂供应系统担负着供应二氧化硫吸收剂的重要任务。针对该系统在实际运行中存在的突出问题,进行了详细的原因分析,给出了预防措施和解决方法,并在此基础上提出了若干技术改进方案,供业内参考。     

Effects of Future Infrastructure Development on Threat Status and Occurrence of Amazonian Birds

Abstract:  Researchers predict that new infrastructure development will sharply increase the rate and extent of deforestation in the Brazilian Amazon. There are no predictions, however, of which species it will affect. We used a spatially explicit model that predicts the location of deforestation in the Brazilian Amazon by 2020 on the basis of historical patterns of deforestation following infrastructure development. We overlaid the predicted deforested areas onto maps of bird ranges to estimate the amount of habitat loss within species ranges. We also estimated the amount of habitat loss within modified ecoregions, which were used as surrogates for areas of bird endemism. We then used the extent of occurrence criterion of the World Conservation Union to predict the future conservation status of birds in the Brazilian Amazon. At current rates of development, our results show that at least 16 species will qualify as threatened or will lose more than half of their forested habitat. We also identified several subspecies and isolated populations that would also qualify as threatened. Most of the taxa we identified are not currently listed as threatened, and the majority are associated with riverine habitats, which have been largely ignored in bird conservation in Amazonia. These habitats and the species they hold will be increasingly relevant to conservation as river courses are altered and hydroelectric dams are constructed in the Brazilian Amazon.     

能量比值法构建与实证检验——关于农业资源利用效率测算方法的一个改进

农业自然资源利用效率的测算与比较方法较多,如比值分析法、生产函数法、包络分析法、能量效率评价方法、因子-能量评价方法、能值评价方法和指标体系评价方法等.其中,比值分析法因其操作性强、计算简单而被研究者广泛应用.但是,比值分析法存在的一些缺陷使该方法测算的结果受到猜疑.为此,本文试图把"能量"引入到农业资源利用效率中来,采用能量比值法代替传统的比值方法测算农业资源利用效率,并以土地为例,对该方法进行实证比较检验.传统比值法相对能量比值法而言,对于农业资源利用效率评估过于偏大或偏小,利用能量比值法更能够比较农业资源在不同地区、时间段和不同品种之间的利用效率,可为调整农业结构提供参考依据.     

判决反馈用于CDMA中抑制单频干扰的性能分析

提出一种三值滤波器输入和权值修正中均采用判决值的非线性判决反馈干扰抑制器，用于抑制ＣＡＤＭ中的单频干扰。     

Modelling air temperature gradients across managed small streams in western Washington

Leaving riparian strips on both sides of a stream is widely accepted to be an effective management approach in sustaining the valuable functions of stream and riparian ecosystems. The authors' overall objective is to provide microclimatic information for assessing the effectiveness of these strips. During the summer of 1993 and 1994, air temperatures were collected across 20 small, buffered streams in western Washington, USA, including five streams sampled before and after harvesting of the forest. These data were statistically analysed to examine the effects of adjacent harvesting with preservation of 16–72 m riparian forest strips. Regression models were developed to predict air temperatures at the stream and buffer edges, the difference between two locations, and seasonal changes. The authors found: (1) clearcutting in winter 1993/94 increased air temperature on the stream by up to 4°C, and changes in temperature variability from the stream to the upland, measured by coefficient of variation (CV), were significantly higher after harvesting; (2) forest buffers provided minimal protection for stream air temperature during the middle of summer (July) but were more effective early and late in the season; (3) buffer width was not a significant variable in predicting stream air temperature, suggesting that even a 72 m buffer was not sufficient to maintain a stream environment because of greater depth of edge influences.1998 Academic Press     

快速测定化学需氧量的改进

在水质CODcr快速测定中，由于取样量仅2．00mL，对含较多有机颗粒物的浑浊水样，其取样的均匀性、代表性较差，往往会带来很大误差。样品置于水浴超声器中作用5min是一种理想的改进措施。     

东川市生态环境现状及其改善对策

东川是我国铜矿主产地，又是泥石流灾害多发区。由于特殊地质－地貌背景和近期人类经济－工程活动，这一区域土地沙石化进程在加剧，环境质量在下降。通过实际调查并运用生态经济学原理，系统地分析了生态环境现状，提出了保护和改善环境的对策。     

疏浚底泥改良土壤理化性质促进芦苇快速定植研究

采用盆栽实验考察了湖泊疏浚底泥和河道疏浚底泥不同利用方式下对土壤基底性质的改良进而促进水生植物芦苇快速定植扩繁效果.试验结果表明,湖泊底泥在竹炭改良利用方式下(L-A实验组)可提高芦苇单位面积分蘖数增长率,最高可达(3.06±0.36) m~(-2)·d~(-1),在与绿化土壤混合利用方式下(L-M实验组)可提高芦苇株高,最高达(155.5±0.7) cm;而河道底泥在与绿化土壤混合利用方式下(R-M实验组)芦苇的单位面积分蘖数增长率和株高效果最优,分别可达(4.76±0.18) m~(-2)·d~(-1)和(139.5±3.5) cm.分析原因发现,施加底泥可以明显降低土壤容重,并提高有机质和磷含量,从而促进芦苇分蘖数增长率的提高.基底微生物群落多样性和群落中Micrococcaceae(微球菌)的丰度也显著提高,进一步证实了施加底泥可以改良基底理化性质从而促进芦苇快速定植.     

REHABILITATION OF WATERSHEDS WITH INCISING CHANNELS1

ABSTRACT: Channel incision is a pervasive problem that threatens infrastructure, destroys arable land, and degrades environmental resources. A program initiated in 1983 is developing technology for rehabilitation of watersheds with erosion and sedimentation problems caused by incision. Demonstration projects are located in 15 watersheds in the hills of northwest Mississippi. Watershed sizes range from 0.89 to 1,590 km², and measured suspended sediment yields average about 1,100 t km^-2-yr^-1. Water quality is generally adequate to support aquatic organisms, but physical habitat conditions are poor. Rehabilitation measures, which are selected and laid out using a subjective integration of hydraulic and geotechnical stability analyses, include grade controls, bank protection, and small reservoirs. Aquatic habitat studies indicate that stone-protected stilling basins below grade-control weirs and habitats associated with drop pipes and stone spur dikes are assets to erosion-damaged streams. Additional recovery of habitat resources using modified stone stabilization designs, woody vegetation plantings, and reservoir outlets designed to provide non-zero minimum flows is under investigation.