长期不同施氮水平对草原植物群落结构的影响

为探讨施氮对贝加尔针茅草原植物群落结构的影响,该研究于内蒙古贝加尔针茅草原设置不同施氮水平0(N0)、15(N15)、30(N30)、50(N50)、100(N100)、150(N150)、200(N200)和300(N300)kg·hm-2·a-1,研究连续施氮9年后贝加尔针茅草原群落物种组成、重要值、多样性及生物量等指标对不同施氮水平的响应。结果表明:(1)长期施氮导致植物群落物种组成发生了明显的变化,在高浓度氮素添加量下群落物种数最低,但可显著提高优势种在群落中的重要值(P<0.05)。(2)长期施氮使贝加尔针茅草原植物多样性指数不同程度地降低,使优势度指数增加,其中N300添加水平效果最为明显(P<0.05)。(3)长期施氮使草原植被生产力(地上、地下生物量)整体呈先上升后下降的趋势,地上生物量在N100水平时出现峰值,地下生物量在N50水平时出现最大值(P<0.05),且根系分布具有明显的表聚特征(0~10 cm)。(4)RDA分析表明,寸草苔和狭叶柴胡地上生物量与土壤pH呈显著正相关关系(P<0.05);展枝唐松草和二裂委陵菜地上生物量与土壤有机质含量呈显著正相关关系(P<0.05)。研究认为,长期不同施氮水平均可改变贝加尔针茅草原群落物种组成,降低物种多样性,对植物群落结构有着明显的影响。     

不同音乐环境对小鼠生长发育的影响

目的探讨音乐对小鼠生长发育的影响。方法采用30只ICR小鼠,在50 dB与60 dB的古筝与葫芦丝音乐环境中,饲养27 d,每3天测定体重一次,每9天测定饲料各种营养消化率一次。结果雌鼠体重在不同音乐环境中都有显著提高（P〈0.05）,且50 dB组高于60 dB组（P〈0.05）。雄鼠体重在古筝音乐环境中有显著提高（P〈0.05）;而在葫芦丝音乐环境中有显著降低。在不同音乐环境中,鼠的各种营养物质消化率无显著差异（P〉0.05）。结论不同的音乐环境对小鼠的体重有显著影响,而对小鼠的各种营养物质的消化率无显著影响。     

我国土壤动物与土壤环境要素相互关系研究进展

土壤动物与土壤生态系统的环境要素密切相关,探明土壤动物与环境要素之间的相互关系对深刻认识土壤生态系统的运行机制、评价土壤生态系统功能具有重要意义.影响土壤动物的环境要素可以分为土壤性质和土壤外部环境两方面,前者主要指土壤基本理化性质、土壤水分和土壤污染状况,后者包括植被、土地利用、地貌和气候等环境要素.本文从以上角度对我国土壤动物与土壤环境要素关系研究进行总结和归纳,认为当前我国相关研究中主要存在以下若干问题：与环境指示作用整合性研究较少,研究方法有待改进,对环境要素的综合性及其时空变异性认识不足.并提出了相应的建议：与实际研究需要相结合,借鉴国外先进方法经验,进行多要素综合研究以及开展大区域长期监测等.     

不同覆盖方式对底泥内源营养盐释放的控制效果

通过底泥内源营养盐释放控制室内模拟试验,考察了塑料包被、斜发沸石、方解石、石英砂和硝酸钙5种覆盖材料对底泥氮磷释放效率的影响,系统分析了各自优劣程度,为实际环境中不同污染背景水体选择适宜的控制技术提供科学依据.结果表明: 不同覆盖材料对底泥总磷释放的控制效果依次为:塑料包被>硝酸钙>斜发沸石>方解石>石英砂;不同覆盖材料对底泥总氮释放的控制效果依次为:斜发沸石>塑料包被>方解石>石英砂>硝酸钙;不同覆盖材料对底泥硝态氮释放的控制效果依次为:塑料包被>斜发沸石>方解石>石英砂>硝酸钙;不同覆盖材料对底泥铵态氮释放的控制效果依次为:硝酸钙>石英砂>斜发沸石>方解石>塑料包被;温度和底泥内源营养盐释放有对应关系,水样中总磷、总氮和硝态氮浓度会随着温度上升而增加,而铵态氮浓度呈下降趋势.     

金花茶叶片性状对不同光环境梯度的响应

金花茶叶片对光环境变化的响应包括质量性状和数量性状的变异。对广西南部金花茶的5个自然种群的光环境及其叶片数量性状等进行观测研究。结果显示:光照强度影响金花茶叶长和叶宽生长间的相关性,当相对光强20‰时,叶片长宽增长具有显著相关性,相关系数≥0.85;在相对光强≥20‰的环境中,相关系数明显变小,相关性不显著;低光照强度下金花茶倾向于形成短窄型叶片,高光照强度则使其倾向于形成长阔型叶片。并对该研究揭示的这种叶片数量性状变异规律在金花茶保护中的应用前景进行了探讨。     

象山港网箱养殖对近海沉积物细菌群落的影响

微生物在有机物质分解、能量转移等生物地化循环中起着重要作用,研究养殖活动对沉积物中微生物多样性的影响对正确评价近海生态系统结构和功能具有重要意义.结合沉积物的理化分析(T、pH、Eh和SO2-),通过T-RFLP(末端限制性片段长度多态性)分析了象山港网箱养殖对近海不同深度沉积物中细菌群落结构和多样性的影响,构建了对照区0-5 cm沉积物样品的细菌16S rRNA基因克隆文库,并进行了系统发育分析.结果表明,近海网箱养殖活动不但使象山港沉积物Eh、pH值等理化性质有所改变,而且使细菌的群落结构也发生了变化,变形细菌纲细菌的相对丰度降低,细菌群落的多样性和均匀度也显著降低,致使近海沉积物细菌群落由多样性高的稳定结构向多样性降低的不稳定结构转变.     

福建漳江口红树林沉积物重金属汞(Hg)的分布特征

对福建漳江口红树林沉积物中重金属汞(Hg)含量的时空分布进行了研究。结果表明漳江口红树林湿地汞含量为0.0815 mg•kg–1—0.3431 mg•kg–1。在潮间带水平分布上, 从光滩到高潮位汞含量显著上升(P<0.05), 相对光滩, 红树林沉积物更易富集汞, 其中高潮位红树林底泥中汞含量最高。在垂直方向上, 大多数的汞富集在表层及亚表层, 随着深度的加深, 汞含量呈现下降趋势。汞在红树林湿地沉积物中的积累主要与有机碳(TOC), 含水率, 盐度相关。从计算的单一污染指数(Pi)来看, 漳江口地区汞污染等级为Ⅲ级以下, 大多数采样点属于自由污染或轻度污染。就该地区汞污染的时空变化趋势以及和其他红树林区汞污染状况的对比来看, 漳江口地区存在一定程度的汞污染威胁加剧的现象, 值得引起注意。     

Sulphate reduction and sulphur cycling in lake sediments: a review

1. The concentration of sulphate is low in lakes and sulphur cycling has often been neglected in studies of organic matter diagenesis in lake sediments. The cycling of sulphur is, however, both spatially and temporally dynamic and strongly influences many biogeochemical reactions in sediments, such as the binding of phosphorus. This review examines the control of sulphate reduction and sulphur cycling in sediments of lakes with different trophic status. 2. The factors that control the rate of sulphate reduction have not been identified with certainty in the various environments because many factors are involved, e.g. oxygen and sulphate concentrations, temperature and organic matter availability. 3. Sulphate reduction is less significant under oligotrophic conditions, where mineralization is dominated by oxic decomposition. The supply of organic matter may not be sufficient to support sulphate reduction in the anoxic parts of sediments and, also, sulphate availability may control the rate as the concentration is generally low in oligotrophic lakes. 4. There is a potential for significant sulphate reduction in eutrophic lakes, as both the availability of organic matter and sulphate concentration are often higher than in oligotrophic lakes. Sulphate is rapidly depleted with sediment depth, however, and methanogenesis is generally the most important process in overall carbon mineralization. Sulphate reduction is generally low in acidic lakes because of low sulphate availability and reduced microbial activity. 5. It is still unclear which of the forms of sulphur deposits are the most important and under which conditions burial occurs. Sulphur deposition is controlled by the rate of sulphate reduction and reoxidation. Reoxidation of sulphides occurs rapidly through several pathways, both under oxic and anoxic conditions. Only a few studies have been able to examine the importance of reoxidation, but it is hypothesized that most of the reoxidation takes place under anoxic conditions and that disproportionation is often involved. The presence of sulphide oxidizing bacteria, benthic fauna and rooted macrophytes may substantially enhance oxic reoxidation. Deposition of sulphur is generally higher in eutrophic than in oligotrophic lakes because of a number of factors: a higher rate of sulphate reduction, enhanced sedimentation of organic sulphur and less reoxidation as a result of reduced penetration of oxygen into the sediments, a lack of faunal activity and rooted macrophytes.     

不同生态环境对蒲公英超氧物歧化酶（SOD）的影响

选择干生,湿生,阳生,阴生四种生境中生长的蒲公英Taraxacum mongolicum Hand.-Mazz分根,叶,花分别测定了SOD活性和比活性,并比较了同工酶谱的变化情况,结果表明不同生境未能改变SOD的同工酶条带数,但对其活性大小有影响,这种影响尤其表现在根上,湿生和阴生根的SOD活性明显高于干生和阳生根的SOD活性,显示出蒲公英的不同器官适应不同的环境效应。     

Microhabitat selection by tadpoles of <Emphasis Type="Italic">Buergeria japonica</Emphasis> inhabiting the coastal area

Microhabitat selection is particularly important to increase the survival rate and reproductive success of animals inhabiting heterogeneous environments. I investigated microhabitat selection of Buergeria japonica tadpoles inhabiting the stream in a coastal area to reveal how animals select their appropriate habitat under heterogeneous and unstable environments on the subtropical Okinawa Island of Japan. Tadpoles are sensitive to subtle environmental changes, and the mouths of streams in coastal areas that have intense environmental fluctuations such as desiccation and sudden changes in current velocity would be risky habitat for tadpoles. Tadpoles of B. japonica can inhabit both lotic and lentic systems. Field observations showed that, among six physical factors (water depth, water temperature, salinity, pH, current velocity, and substrate), current velocity and water temperature were key factors in microhabitat selection by tadpoles. It is likely that tadpoles stay at low current velocity sites to reduce the probability of being washed out to the sea by a sudden squall and that selection of warmer sites would accelerate development of tadpoles so as to escape the heterogeneous aquatic habitat sooner.