METHOD TO IDENTIFY EFFECTWE RIPARIAN BUFFER WIDTHS FOR ATLANTIC SALMON HABITAT PROTECTION1

ABSTRACT: Successful restoration of declining anadromous species is dependent upon effective riparian buffer zone management. Natural resource managers, policy developers and local conservation groups require science‐based information concerning the width at which a given buffer will be effective for its stated purpose. This paper summarizes a method developed in 1999 to determine effective riparian buffer widths for Atlantic salmon habitat protection as part of the Atlantic Salmon Conservation Plan for Seven Maine Rivers. A major assumption of the method is that no two buffers are alike with respect to their effectiveness and that various buffer characteristics dictate the required width for a given level of effectiveness. The method uses a predictive model that generates suggested riparian buffer widths as a function of specific, measurable buffer characteristics (such as slope, soil characteristics, and plant community structure and density) that affect buffer function. The method utilizes a variable‐width, two‐zone approach and specifies land uses that are consistent with desired buffer function within the two zones.     

Disentangling the effects of heterogeneity, stochastic dynamics and sampling in a community of aquatic insects

A dynamic and heterogeneous species abundance model generating the lognormal species abundance distribution is fitted to time series of species data from an assemblage of stoneflies and mayflies (Plecoptera and Ephemeroptera) of an aquatic insect community collected over a period of 15 years. In each year except one, we analyze 5 parallel samples taken at the same time of the season giving information about the over-dispersion in the sampling relative to the Poisson distribution. Results are derived from a correlation analysis, where the correlation in the bivariate normal distribution of log abundance is used as measurement of similarity between communities. The analysis enables decomposition of the variance of the lognormal species abundance distribution into three components due to heterogeneity among species, stochastic dynamics driven by environmental noise, and over-dispersion in sampling, accounting for 62.9, 30.6 and 6.5% of the total variance, respectively. Corrected for sampling the heterogeneity and stochastic components accordingly account for 67.3 and 32.7% of the among species variance in log abundance. By using this method, it is possible to disentangle the effect of heterogeneity and stochastic dynamics by quantifying these components and correctly remove sampling effects on the observed species abundance distribution.     

Positive long-term effect of mulching on species and functional trait diversity in a nutrient-poor mountain meadow in Central Europe

Oligotrophic mountain meadows are threatened biodiversity hotspots throughout Europe. The traditional summer hay-making followed by autumn grazing is no longer economic and question is whether alternative managements can maintain both plant species and functional diversity typical of these habitats. In the Bohemian Forest Mts., we applied three treatments (mowing once a year - i.e., cutting and removing the biomass, mulching once a year - cutting and leaving the crushed biomass to decompose in situ, fallowing - no cutting) in order to assess temporal changes in meadow vegetation, plant trait composition and biomass production in a 13-year experiment. We recorded for each species twenty-five traits as to be most informative of plant strategies related to growth, resource acquisition and carbon-water economy. We compared different components of trait composition (community averages that mostly reflect traits of dominant species vs. the Rao index of functional diversity that reflects trait dissimilarity among species) and their impact on biomass production. We show that mulching promotes species and functional diversity by facilitating heliophilous forbs and legumes with more acquisitive strategies in resource use and release, e.g., higher foliar N and P content. This occurs at the expense of tall grasses (with resource-retentive strategies, e.g., high leaf dry matter content) which dominate the mown and fallow plots. The divergence in most quantitative traits indicates that niche complementarity is the dominant assembly process in mulched plots, which can prevent competitive exclusion and enable species coexistence. The divergent development was detected only after 5-6 years. This slow floristic and functional response is caused by acidity of soil and severe mountain climate that preclude rapid responses of vegetation to land-use changes. We conclude that mulching represents a good compromise maintaining both plant species and functional diversity as well as a relatively high biomass production. Mowing without grazing leads to gradual nutrient loss and thus reduces the productivity and diversity in these oligotrophic ecosystems. Fallowing causes gradual loss in diversity by increased grass competition and litter accumulation.     

风力发电场环境监理中风机敏感距离的测量

风电项目环境监理过程中需重点关注风机环境防护距离内有无环境敏感点。介绍了几种适用于风电项目环境监理测量距离的方法,并且对每种方法的适用范围及操作做了详细阐述。     

产电微生物反应系统内电阻的快速测定

内阻是表征反应器内部状态的重要参数.传统的极化曲线法存在耗时长、对系统日常运行干扰严重等问题.本研究尝试通过减小可变外阻的调节范围,使系统内阻的测定可以在非常接近于系统日常运行状态的有限外阻变化范围内完成,在实现内阻快速测定的同时,有效控制了测定过程对系统运行状态的干扰.在外阻调节步长为10Ω,电压稳定时间1 min条件下,单次测定用时缩短到10 min,测定前后系统电流的变化1.5%.不同稳定时间对内阻测定结果的影响不大.减小外阻调节步长虽然有助于降低测量过程对系统运行的干扰,但在相同万用表精度下,测量误差有增大的趋势.本研究所提出的方法能够比较实时地反映系统内阻的变化情况.     

7种阔叶植物群落降噪的临界达标宽度

选取南京市部分主干路道路绿地的7种阔叶植物群落,通过沿道路纵向每间隔5m以及不定距移动测量,结果表明:测量时间段内路缘处噪声的等效连续A声级平均值都超出GB3096-2008中相应规定的限制,其中最高的超出6dB,最低的超出1.3dB;同一阔叶植物群落,随着离开路缘的距离增加,降噪效果更加明显;不同的阔叶植物群落在同一距离处的降噪效果不同,这与植物群落的组成和内部结构特征有密切关系;植物群落的降噪效果与林带宽度并非都呈线性关系;7种阔叶植物群落达到声环境功能区环境噪声限值的临界宽度值集中在5～15m范围内;达到一定宽度的阔叶植物群落可以基本满足城市主干路的降噪要求,在道路绿化中可以广泛应用。     

高位巷瓦斯抽采下采空区自燃危险性数值分析及应用

针对大流量高位巷瓦斯抽采可能诱发采空区自燃问题,以南山矿18层5分段综放面为研究背景,构建采空区气体渗流分析模型。利用变渗透系数和Forchheimer方程,求解非线性流与层流并存下采空区三维氧气分布。结果表明:高位巷瓦斯抽采使工作面氧气更易沿漏风方向采空区纵深发展,氧化带总体宽度会随抽放流量的提高而增加。在进风侧氧气分布后移程度较小,而回风侧受抽放负压显著影响,出现明显氧气富集区。上下隅角封堵配合注氮,会降低抽放对氧气渗入的诱导影响。依据研究结论,利用综合防火措施消除了高位巷附近潜在的自燃危险。     

生态修复后九曲湾水库浮游动物优势种演替及生态位特征分析

探究生态修复后九曲湾水库浮游动物优势种生态位特征及主要影响因素,为九曲湾水库及相关饮用水源地水库生态系统的保护、修复提供理论和技术支撑.于生态修复前2014年4月(平稳期)、2014年7月(爆发期),2015—2016年生态修复后12月(枯水期)、4月(平水期)、7月(丰水期)进行数据采集,采用优势度、Levins生态...     

Allometric models for the estimation of above- and below-ground biomass of Jatropha curcas L. in semi-arid regions of Southern India

Jatropha curcas L. (Jatropha) is an important multipurpose tree valued for oil. In India, plans are underway to bring substantial area under this crop for meeting the biofuel requirements of the country. A study was conducted to develop allometric relationships in Jatropha to predict various biomass-related components (above ground and below ground) using easily measurable attributes, viz. collar diameter, tree height, number of branches, crown diameter, and crown depth. Further, it was aimed to establish the reliability of these relationships using an independent dataset obtained from varied management situations. Destructive sampling was carried out during the rainy season of 2011, when Jatropha plants were eight years old. Highly significant allometric relationships (F-values significant at 1% level) were obtained while predicting various biomass components (above, below, and total) using easily measurable attributes with R² values ranging from 0.89 to 0.98. Of all the predictors, collar diameter exhibited a highly significant relationship with total dry biomass per plant (R² = 0.97). The allometric relationships developed were validated with an independent dataset. The allometric relationships developed would serve as valuable tools for estimating total dry biomass production and carbon sequestration with reasonable accuracy in Jatropha systems, as they are proposed to be taken up in substantial area in the years to come.     

pH对磷酸铵镁结晶介稳区、诱导期和反应速率的影响

以p H为控制参数,利用自组装激光测量装置测定了4、20、30和40℃时,磷酸铵镁在水溶液中的溶解度、超饱和度和介稳区宽度等基础数据,分析了不同温度和p H下磷酸铵镁结晶介稳区的变化规律,考察了p H对磷酸铵镁结晶诱导期和结晶反应速率的影响。结果表明,提高溶液的p H,可降低磷酸铵镁在水溶液中的溶解度和超饱和度,但同时磷酸铵镁结晶介稳区宽度有所增加;磷酸铵镁的溶解度和超饱和度随温度的升高呈现上升的趋势,而磷酸铵镁的结晶介稳区宽度则随温度的升高而变窄,提高溶液中MAP的物质浓度也会压缩结晶介稳区宽度;随着溶液p H的升高,磷酸铵镁的结晶诱导期逐渐缩短,同时其结晶反应速率也有明显的提升。在磷酸铵镁结晶除磷过程中,可以通过控制p H来优化反应工艺条件,促进磷酸铵镁结晶反应的进行。