Song type variants and aggressive context

We asked whether switching among song type variants functions as a graded signal of aggression in song sparrows (Melospiza melodia). Song type variants are different versions of a given song type and are defined by much smaller acoustic differences than those defining separate song types. The principal evidence that switching between song types functions as an aggressive signal, in song sparrows and other species, is that song type switching frequencies increase during aggressive contexts, for example during simulated territorial intrusions. We tested whether variant switching frequencies change in the same way, using playback of conspecific song to simulate intrusions. Male song sparrows showed a significant increase in variant switching frequencies during intrusion relative to before intrusion. After intrusions, variant switching frequencies returned to pre-intrusion levels. These results are consistent with the hypothesis that variant switching is a graded aggressive signal, but other interpretations are possible, for example, that variant switching is a signal of submission or represents simple production error. Received: 20 January 2000 / Revised: 15 July 2000 / Accepted: 30 July 2000     

Seasonal variation and sources of atmospheric polycyclic aromatic hydrocarbons in a background site on the Tibetan Plateau

The study of atmospheric polycyclic aromatic hydrocarbons (PAHs) in northeastern Tibetan Plateau with fragile ecological environment and complex atmospheric circulation system is blank. To understand the characteristics and sources of persistent organic pollutants in the atmosphere of the northeastern Tibetan Plateau, we monitored levels in the central Qilian Mountain. From 2016 to 2017, we collected 45-pair (particle + gas) samples using active air samplers to investigate the sources, transport paths, and their influencing factors. Sources of PAHs were analysed with a source diagnostic model, and atmospheric transport paths were calculated. The concentration range for ∑₁₅PAHs was 439–4666 pg/m³, and the average was 2015 pg/m³. The PAHs in central Qilian Mountain are mainly low molecular weight (LMW) PAHs. Winter concentrations of PAHs were higher than those in summer. The transport of PAHs is mainly affected by westerlies, and there are seasonal differences. Source analysis showed that PAHs mainly came from coal and biomass combustion and vehicle emissions, with seasonal differences. This study clarifies the concentration and seasonal variation of PAHs in the northern Tibetan Plateau, which is conducive to understanding the atmospheric transport process and fate of pollutants. The background site of Qilian Mountains located in the Silk Road economic belt has the value and significance of long-term observation of pollutants.     

Sedimentation and seasonal variation of hexachlorocyclohexanes in sediments in a eutrophic lake,China

Hexachlorocyclohexane (HCH) concentrations in sediments and sediment trap fluxes of particulate organic carbon and HCHs were measured bi-weekly from March 31 to October 18, 2006 in an urban eutrophic lake in Tianjin, China, in order to investigate sedimentation and seasonal variation of HCHs in sediments. HCH concentrations (dry weight basis) ranged from 2.2 to 20.2 ng/g (mean 7.7 ng/g) in surface sediments and from 26.6 to 972.7 ng/g (mean 187.0 ng/g) in settling particles, respectively. A clear seasonal variation in HCH sedimentation and HCH concentrations in sediments was observed. The maximal HCH deposition occurred following a spring phytoplankton bloom. The average flux of HCHs to sediment was approximately 21-fold higher in April to mid-June as compared to late June to October. This was attributed to the high vertical fluxes at the end of the spring phytoplankton bloom. The maximum values of HCH concentrations in sediments were observed in mid-June to late July. Concentrations of HCHs in sediments from the eutrophic lake were well-correlated with organic carbon contents in sediments. The annual sediment trap flux of HCHs in the eutrophic lake, which was estimated using data obtained in the eutrophic lake, was 117 μ g/m² yr, about 72% of which was attributed to the sedimentation corresponding to spring bloom phytoplankton deposition in late May to mid-June. The high sediment trap flux of HCHs in the eutrophic lake was related to serious local contamination.     

中国水稻土氮密度变异性的幅度效应研究

基于全国第二次土壤普查的1 491个水稻土剖面数据,研究了行政区幅度（行政大区、省级、地区级）和土壤区幅度（土壤区、土壤带、土区）下水稻土氮密度的变异情况及其对幅度拓展的响应。结果表明,中国水稻土0-20 cm和0-100 cm土壤平均氮密度为18.7 t.hm^-2和12.4 t.hm^-2,土壤氮素的空间变异性总体随幅度拓展而增大。在不同土壤区幅度下,0-20 cm全氮密度组内和组间变异性随研究区幅度的减小而减小;从土壤区到土区尺度,0-100 cm全氮密度组间变异率从250%左右下降至不足50%,而在行政大区和省级尺度时全氮密度的组间变异性没有太大变化,变异率都小于100%,到地级市尺度时,组间变异率又达到了400%,说明同一地区所选择的研究幅度尺度不一样氮密度变异率差异也很大。因此,在今后的水稻土调查采样设计时,根据不同幅度尺度的变异率大小来选择合适的布点方式和样点数是十分必要的。     

Relative Importance of the Area and Shape of Patches to the Diversity of Multiple Taxa

Abstract: Although enhancing reserve shape has been suggested as an alternative to enlarging nature reserves, the importance of reserve shape relative to reserve area remains unclear. Here we examined the relative importance of area and shape of forest patches to species richness, species composition, and species abundance (abundance of each species) for 3 taxa (33 birds, 41 butterflies, and 91 forest‐floor plants) in a fragmented landscape in central Hokkaido, northern Japan. We grouped the species according to their potential edge responses (interior‐, neutral‐, and edge‐species groups for birds and forest‐floor plants, woodland‐ and open‐land‐species groups for butterflies) and analyzed them separately. We used a shape index that was independent of area as an index of shape circularization. Hierarchical partitioning and variation partitioning revealed that patch area was generally more important than patch shape for species richness and species composition of birds and butterflies. For forest‐floor plants, effects of patch area and shape were small, whereas effects of local forest structure were large. Patch area and circularization generally increased abundances of interior species of birds and forest‐floor plants and woodland species of butterflies. Nevertheless, only patch circularization increased abundances of 1 woodland species of butterfly and 2 and 6 interior species of birds and forest‐floor plants, respectively. We did not find any significant interaction effects between patch area and shape. Our results suggest that although reserves generally should be large and circular, there is a trade‐off between patch area and shape, which should be taken into consideration when managing reserves.     

湿热流域化学风化与水化学组成季节变化——以西枝江流域为例

为研究湿热中小流域岩石化学风化与化学径流组成的关系，选取硅酸盐岩为主的东江一级支流西枝江流域，分别于2011年1月和7月采集干流和支流水样品并测量其化学组成，运用图解法和正演模型对西枝江流域水化学组成进行分析和定量计算。结果表明，Na⁺和HCO₃^-为西枝江流域水体的主要阳离子和阴离子，两者分别占总阳离子和总阴离子的55%以上。硅酸盐矿物的化学风化对水体阳离子的贡献最大（45.8%），其次是人类活动和碳酸盐矿物风化的贡献（分别是24.7%和22.0%），大气输入对阳离子的贡献相对较少（7.5%）。受碳酸盐矿物风化和人类活动影响较大的支流水化学组成季节变化较大，受硅酸盐矿物化学风化影响的河流水化学组成季节变化不明显。西枝江流域硅酸盐矿物和碳酸盐矿物化学风化速率分别是8.27和56.95 t/（km²·a），二者化学风化对大气CO₂的消耗速率分别为0.80×10⁵和8.52×10⁵ mol/（km²·a）。     

受引黄影响的河流沉积物细菌群落季节变化

河流沉积物细菌群落的季节变化对碳、氮循环和水环境演化有明显的影响.然而,受调水干预的河流沉积物细菌群落季节性变化尚不明确.本文基于16S rRNA高通量测序技术,研究了中纬度地区受引黄影响的汾河上游沉积物细菌群落组成、结构和多样性的季节变化.结果表明,在引黄调水干预下受水河流细菌群落的季节性变化仍然显著.夏季温度适宜,河流沉积物细菌群落多样性较冬季高.核心菌群组成和结构随季节变化,然而丛毛单胞菌、黄杆菌、黄单胞菌和红环菌等的优势地位不随季节改变.河水水温和ORP的季节变化显著,是造成河流沉积物细菌群落季节变化的主导因子.水质较差的黄河水引入汾河后导致沉积物细菌群落多样性显著提高.引水对河流沉积物细菌群落的影响在夏季较冬季高20%左右.引黄调水对汾河沉积物细菌群落的影响大于季节变化的影响.