黑河流域草地资源保护与建设

黑河流域除绿洲地区外有160万hm2的草地,进行草地分户、围栏封育、人工改良草地;牧户按地定畜、优化牧场、推广良种、改良畜群;按草定牧、实行休牧和轮牧;革新观念、子羔出栏、加速出栏周期、保障牧民增收等措施可保护草地资源,加速草地建设,繁荣牧区经济.     

不同土地利用方式下表层土壤大团聚体特征

土壤大团聚体含量能表征土壤结构稳定性,反映土壤结构变化趋势。本研究在辽河干流中下游流域主要沙化区分析湿地、林地、农田和草地4种土地利用方式对0-20cm土层土壤大团聚体(0.25 mm)含量和稳定性的影响,及各粒径大团聚体的空间异质性,并进行空间插值模拟其分布。结果显示,农田土壤团聚体破坏率最大,达到46.98%,林地最小,为26.36%;依据土壤水稳性大团聚体含量、团聚体颗粒平均重量直径和几何平均直径,评价土壤结构稳定性强弱为湿地林地农田草地;4种土地利用导致土壤大团聚体稳定性差异显著(P0.05),湿地和草地之间的差异性最显著;湿地土壤结构相对最好,其次是林地和农田,草地相对最差。本研究结果可为辽河干流流域土地沙化程度评价及分区治理提供参考依据。     

基于线粒体DNA Cyt b研究城市化对上海金线侧褶蛙遗传结构的影响

城市化在全球范围内快速扩张,已经成为影响物种进化的重要力量。两栖动物的迁移能力较弱,城市化导致两栖类被完全或部分的隔离,丢失更多的遗传多样性。本研究对上海市的金线侧褶蛙(Pelophylax plancyi)的mtDNA Cyt b部分序列进行分析,共扩增出235条序列,获得61个单倍型。研究表明城市区域遗传多样性较低,上海市的金线侧褶蛙分化程度处于中低的水平(Max F_ST=0.296;Min F_ST=0.004),各种群之间遗传分化有限。黄浦江及其支流可能作为水上扩散通道,有助于基因交流,各城市公园之间的遗传分化差异并不显著;而长江阻碍了种群之间的交流,城市公园和郊区,以及岛屿种群之间的遗传分化显著。此外,单倍型网络和系统发育分析表明,上海的金线侧褶蛙并没有对应城市化程度形成相应的单系。     

黄河源区“黑土滩”混播草地牧草植物量及营养动态初探

黄河源区的极度退化草地——"黑土滩",改建成人工草地是一种恢复退化草地的重要途径,同时可以收获大量饲草。对"黑土滩"混播草地(垂穗披碱草Elymus nutans+中华羊茅Festuca sinensis+碱茅Puc-cinellia distans+冷地早熟禾Poa crymophila+赖草Leymus secalinus)的生产力和营养价值动态进行了研究,分析了放牧对草地生产力的影响。结果表明,从生长高峰期8月到翌年4月,草地生产力自然损失量为144.3 g/m2,损失率为34.9%。这期间放牧利用导致牧草被采食187.2 g/m2。传统的放牧利用,使该类人工草地利用率为45.2%。冷季草地牧草营养价值全都下降,粗蛋白含量降低了69.86%,粗脂肪降低了65.85%。该"黑土滩"混播草地在夏季属碳氮营养型(CN),冬季属碳营养型(C)。因此建议,"黑土滩"混播草地在夏季生长高峰期适度进行人工割草,冬季进行适度放牧利用。     

Ecological impacts of small hydropower plants on headwater stream fish: from individual to community effects

Hydroelectricity is increasingly used worldwide as a source of renewable energy, and many mountain ranges have dozens or hundreds of hydropower plants, with many more being under construction or planned. Although the ecological impacts of large dams are relatively well known, the effects of small hydropower plants and their weirs have been much less investigated. We studied the effects of water diversion of small hydropower plants on fish assemblages in the upper Ter river basin (Catalonia, NE Spain), which has headwater reaches with good water quality and no large dams but many of such plants. We studied fish populations and habitat features on control and impacted reaches for water diversion of 16 hydropower plants. In the impacted reaches, there was a significantly lower presence of refuges for fish, poorer habitat quality, more pools and less riffles and macrophytes, and shallower water levels. We also observed higher fish abundance, larger mean fish size and better fish condition in the control than in impacted reaches, although the results were species‐specific. Accordingly, species composition was also affected, with lower relative abundance of brown trout (Salmo trutta) and Pyrenean minnow (Phoxinus bigerri) in the impacted reaches and higher presence of stone loach (Barbatula quignardi) and Mediterranean barbel (Barbus meridionalis). Our study highlights the effects of water diversion of small hydropower plants from the individual to the population and community levels but probably underestimates them, urging for further assessment and mitigation of these ecological impacts.     

黄河源区“黑土滩”退化草地CO2排放研究

采用静态箱-气相色谱法,对黄河源区“黑土滩”退化草地CO2释放特征的研究结果表明：“黑土滩”3种不同处理：“黑土滩”植被-土壤系统呼吸（BC）,土壤呼吸（BJ）和土壤微生物呼吸（BL）的CO2释放速率日变化具有相似性,均呈现出明显的单峰型特点,且白天大于夜间;CO2释放速率季节动态变化明显,且3者的变化趋势基本一致;“黑土滩”植被-土壤系统呼吸与地表温度及5cm地温呈极显著的正相关性（P〈0．01）;而土壤微生物呼吸与0～10cm土壤水分含量相关显著（P〈0．05）。     

黄河三角洲新生湿地不同植被类型土壤的微生物分布特征

为探明黄河三角洲新生湿地土壤微生物分布特征,选取盐地碱蓬(Suaedasalsa)、柽柳(Tamarix chinensis)、芦苇(Phragmites communis)和拂子茅(Calamagrostis epigeios)4种湿地植被土壤,分春、夏、秋3个季节对其中细菌、真菌和放线菌数量组成和分布特征进行了研究。结果表明:不同植被类型湿地土壤中各类微生物数量差别明显,但总体上均偏少,而且优势种类非常明显,以细菌为主,放线菌居中,真菌最少;不同微生物数量上具有明显的季节分布特征,除拂子茅湿地细菌群落外,其他各群落数量均为夏季高,春、秋低;湿地土壤中微生物总量分布存在明显的根际效应,其中细菌的根际效应最为明显;土壤中氮和磷(总氮、总磷、速效氮、速效磷)含量对细菌的数量影响最明显;真菌分布与氮的含量关系密切,但与磷素关系不大;放线菌分布与氮含量相关性小,与磷素呈负相关;微生物数量与土壤pH值和电导率呈一定程度的负相关。本区土壤微生物分布与植被类型、土壤盐分和养分关系密切,且具有明显的季节动态。     

渭北旱塬区土壤质量对人工植被恢复模式的响应

以植被恢复土壤效果评价7种人工植被恢复模式,应用灰色关联模型和聚类分析方法研究渭北旱塬区植被恢复对土壤综合质量的影响,以确定最优植被恢复模式。结果表明：不同人工植被恢复模式对土壤质量有很大影响,与对照（农地）相比,恢复年限为5年、10年紫花苜蓿（Medicago sativa）草地和恢复年限为30年刺槐（Robinia pseudoacacia）林地均提高了土壤质量,其中10年紫花苜蓿草地恢复效果最好。随着退耕还林还草工程的实施,在渭北旱塬区,种植牧草、建植乔木是较好的生态重建和植被恢复方式。     

青土湖水面形成区土壤颗粒组成与化学特性变化

青土湖输水作为石羊河流域治理的一项关键措施,对保护湖区水资源和生态环境具有重要意义。在距青土湖水面边缘东南方向0-450 m的10个样点中分3层取0-60 cm土样,测定土壤粒径的质量百分比与全氮、全磷、全钾和电导率,分析青土湖水面形成后土壤颗粒组成与化学特性变化。结果表明, 随着离水面边缘距离的增加,土壤颗粒与化学特性呈有规律的增减变化,土壤粘粉粒组成与其全磷、全钾之间存在正线性相关。青土湖水面形成加剧了距水面边缘0-150 m处的土壤理化性质变化;土壤细粒及养分出现富集,分别在距水面边缘100-150 m和300 m处达到最大值。因此,土壤养分与土壤细物质的良好相关性表明,土壤粘粉粒变化可作为反映该区域土壤性状变化和评价衡量水面形成后土壤恢复程度的定量指标之一。     

Freshwater snail distribution related to environmental factors in Banco National Park,an urban reserve in the Ivory Coast (West Africa)

Freshwater snails and environmental variables were studied at seven stations along the Banco River (Ivory Coast;West Africa) from March to October 2008. Two species (Physa marmorata (Physidae) and Bulinus forskalii (Planorbidae) were recorded only at one sampling site. This station which received domestic sewage from the neighbouring cities was characterized by the highest conductivity and pH and the lowest values of dissolved oxygen. Multiple stepwise regression analysis showed that snail densities were probably influenced by conductivity, dissolved oxygen, pH, and canopy cover. Also, snail dynamics showed a seasonal pattern, with peak population densities and recruitment of young generations during rainy periods. This study highlighted the impacts of sewage on snail diversity and distribution in the Banco River. Overall, this paper strengthens the viewpoint that the Banco River management should be implemented to lessen the impact of anthropogenic activities on the ecology of the Banco National Park.