Edaphic factors determining variation of two ecotypes of Leymus chinensis in North China

To identify ecotypic variation of L. chinensis, the physiological characteristics and environmental factors were measured and assessed for grey-green and yellow-green ecotypes of L. chinensis grown in the salt-alkalized and aeolian sandy soils. Although both ecotypes presented a similar salt-alkaline tolerance under the experimental conditions, they differed in several aspects. The L. chinensis grown in the aeolian sandy soils had higher water potential and chlorophyll content and lower proline content in their leaves than those grown in the salt-alkalized habitat, and the grey-green ecotype of L. chinensis in both types of soils had higher water potential, chlorophyll and proline contents than the yellow-green ecotype. Besides, grey-green ecotypes had higher salt-alkaline tolerance than the yellow-green ecotype. The stepwise regression analysis showed that soil conductance and pH value were the main ecological factors affecting the physiology of L. chinensis. From the natural distribution of the two ecotypes, we considered that salt-alkaline in the soils is the leading factor in determining ecotypic variation of L. chinensis. The two ecotypes were first named grey-green and yellow-green ecotypes respectively.     

Edaphic factors determining variation of two ecotypes of Leymus chinensis in North China

To identify ecotypic variation of L. chinensis, the physiological characteristics and environmental factors were measured and assessed for grey-green and yellow-green ecotypes of L. chinensis grown in the salt-alkalized and aeolian sandy soils. Although both ecotypes presented a similar salt-alkaline tolerance under the experimental conditions, they differed in several aspects. The L. chinensis grown in the aeolian sandy soils had higher water potential and chlorophyll content and lower proline content in their leaves than those grown in the salt-alkalized habitat, and the grey-green ecotype of L. chinensis in both types of soils had higher water potential, chlorophyll and proline contents than the yellow-green ecotype. Besides, grey-green ecotypes had higher salt-alkaline tolerance than the yellow-green ecotype. The stepwise regression analysis showed that soil conductance and pH value were the main ecological factors affecting the physiology of L. chinensis. From the natural distribution of the two ecotypes, we considered that salt-alkaline in the soils is the leading factor in determining ecotypic variation of L. chinensis. The two ecotypes were first named grey-green and yellow-green ecotypes respectively.     

不同生态型蜈蚣草对砷富集的差异及其机理

 土壤砷污染是全球尤其是东南亚和中国非常突出且亟需解决的环境问题。自砷超富集植物--蜈蚣草（Pteris vittata L.）发现以来,一直是国内外学者研究的一个热点。深入理解蜈蚣草体内砷代谢和富集机制是有效利用植物修复技术治理砷污染土壤的关键。在长期的自然进化过程中,蜈蚣草逐渐分化出不同生态型。已有研究结果显示：不同生态型蜈蚣草在砷富集和砷耐性等方面均存在明显差异。本文在系统分析蜈蚣草砷富集特征、机理的基础上,重点阐述了生态型差异对蜈蚣草砷富集的影响方面的最新研究进展。研究结果显示：非污染生态型与污染生态型蜈蚣草相比砷富集能力更为高效,说明通过选择性的利用合适的蜈蚣草生态型将明显改善植物修复的效率。不同生态型蜈蚣草砷富集与砷耐性差异的分子机理尚不清楚,相关关键功能基因及其过程尚需深入研究。     

松嫩草原羊草种群数量特征对增温和施氮的响应

在松嫩草原野外条件下,采用模拟升温和氮沉降的控制实验探讨了羊草(Leymuschinensis)种群数量特征的响应机制.结果表明:施氮可以显著促进羊草生长,增加羊草种群的高度和密度,加快羊草种群的分蘖速度,进而增加羊草种群在整个群落中的重要值,从而提高羊草的竞争力.增温处理对羊草各项数量特征的影响不显著.增温加施氮处理可使羊草的重要值显著增加,具有协同作用.在整个观测期中,从5月21日到6月17日,增温、施氮处理后的羊草物候期分数均高于对照;从6月24日到8月10日,增温和施氮处理后的羊草物候期分数均低于对照.这说明处理后羊草的春季物候期提前,种子的脱落期延后,落叶推迟,生长期延长.而增温加施氮的交互处理对羊草物候期则无明显影响.     

Genetic diversity, geographic differentiation and evolutionary relationship among ecotypes of Glycine max and G. soja in China

The knowledge of origin and evolution of cultivated soybeans is one of the basic issues in both biology and agronomy of the crop. In order to investigate the nuclear and cytoplasmic genetic diversity, geographic differentiation and genetic relationship among geographic ecotypes of cultivated （Glycine max） and wild （G. soja） soybeans, the allelic profiles at 60 nuclear simple-sequence repeat （nuSSR） loci and 11 chloroplastic SSR （cpSSR） loci evenly distributed on whole genome of 393 landraces and 196 wild accessions from nation-wide growing areas in China were analyzed. （i） The genetic diversity of the wild soybean was obviously larger than that of the cultivated soybean, with their nuSSR and cpSSR alleles as 1067 vs. 980 and 57 vs 44, respectively. Of the 980 nuclear alleles detected in the cultivated soybean, 377 new ones （38.5%） emerged, while of the 44 chloroplastic alleles in the cultivated soybean, seven new ones （15.9%） emerged after domestication. （ii） Among the cultivated geographic ecotypes, those from southern China, including South-Central China, Southwest China and South China possessed relatively great genetic diversity than those from northern China, while among the wild geographic ecotypes, the Middle and Lower Changjiang Valleys wild ecotype showed the highest genetic diversity. （iii） The analysis of molecular variance, association analysis between geographic grouping and molecular marker clustering and analysis of specific-present alleles of ecotypes demonstrated that the geographic differentiation of both cultivated and wild soybeans associated with their genetic differentiation, or in other words, had their relevant genetic bases. （iv） The cluster analysis of all accessions clearly showed that the wild accessions from Middle and Lower Changjiang Valleys and South-Central ＆ Southwest China had relatively small genetic distances with all cultivated accessions. The UPGMA dendrogram among geographic ecotypes further showed that the genetic distances between all cultivated ecotypes and the Middle and Lower Changjiang Valleys wild ecotype were smaller than those with other wild ones, including their local wild counterparts. Therefore, it is inferred that the wild ancestors in southern China, especially those from Middle and Lower Changjiang Valleys might be the common ancestor of all the cultivated soybeans.     

Interannual variation of North China rainfall in rainy season and SSTs in the equatorial eastern Pacific

The rainfall in North China during rainy season （July and August （JA）） exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation of JA North China rainfall are examined. It is found that on the interannual timescale, the JA North China rainfall is associated with significant SST anomalies in the equatorial eastern Pacific, and the North China rainfall and SST anomaly in the equatorial eastern Pacific correspond to the similar variation of the upper-level westerly jet stream over East Asia. A possible mechanism is proposed for the influence of the SST anomalies in the equatorial eastern Pacific on the North China rainfall.     

攀枝花地区昔格达组土壤中微量元素地球化学分异特征

昔格达组在攀枝花地区分布广泛,并成为该区居民的主要集散地和工农业活动区.对昔格达组粘土中微量元素的空间分布及分异特征研究的结果表明:(1)土壤的粒度、矿物组成及成土作用是影响土壤中微量元素浓度的重要条件;(2)人类工矿开发活动是制约土壤中微量元素区域分布形式的重要因素;(3)土壤在不同层位的分异及组合特征既与成土母质有关,也受人为活动的影响.     

三叶木通茎藤生长性状地理变异研究

用11个采集点野生三叶木通(Akebia.trifoliate)单株进行栽培试验,对其茎藤生长性状与采集点地理因子、试验点气候因子之间进行典型相关分析,探讨其地理变异规律.结果表明:三叶木通地理变异的基本模式是以海拔垂直梯度变异为主,纬向渐变为辅;海拔及纬度差异产生了温度和光照差异,水热因子的综合选择作用是三叶木通茎藤生长性状地理变异的重要原因,其中温度和光照是主导因子.海拔或纬度较高的地区,产生了喜温光喜湿的三叶木通气候生态类型;海拔或纬度较低地区,产生了喜温光的三叶木通气候生态类型.     

松嫩盐碱化羊草草甸草原羊草生长及保护酶活性研究

伴随着羊草草地的退化演替过程中,草地土壤盐碱化程度逐渐加重,同时羊草种群的密度、高度、生物量逐渐降低。但是羊草叶片的抗氧化酶活性却出现特异性增加的现象,尤其是CAT的活性在羊草生长的各个时期以及年平均量都出现递增;POD活性虽然在年平均量呈现降低的趋势,但是在羊草生长的前期和末期也出现递增;SOD活性变化比较复杂,但是依然显示出,伴随着草地的盐碱化呈现先降低后增加的趋势。模拟盐碱胁迫也显示出,三种保护酶活性随着盐碱浓度的增加而逐步上升,呈现与野外相似的变化趋势。     

云南纵向岭谷区生态安全评价及影响因素分析

根据云南纵向岭谷区生态环境特点,按照层次分析法建立了生态安全评价指标体系.在应用综合指数法评价云南纵向岭谷区生态安全的基础上,引进灰色系统理论的灰色关联分析方法对影响纵向岭谷区14个地、州、市的生态安全主导因素进行了分析评价.研究表明:云南纵向岭谷区生态安全总体状况良好,植被覆盖度、人口自然增长率、水量变化、产业结构、人口素质、水土流失率和开发土地比例是影响生态安全的主要因素;纵向岭谷区内各区域和流域之间生态安全状况存在差异,生态安全综合指数较高的区域和流域分别是西部地区和怒江流域.针对各个地区生态安全状况的差异及影响因素的不同,该区域应因地制宜地进行生态环境管理,保障自然、经济、生态环境协调发展.     

松辽盆地北部肇州区块沙河子组致密储层主控因素

研究松辽盆地北部肇州区块内下白垩统沙河子组致密储层特征,总结其形成的主控因素。通过对肇州区块沙河子组储层物性、岩石薄片、扫描电镜以及压汞实验资料的分析研究,认为沙河子组致密砂岩层主要为岩屑长石砂岩和长石岩屑砂岩,孔隙式钙质胶结物与泥质杂基构成其主体填隙物,储集空间类型表现为“少见原生孔、多见次生孔、可见微裂缝、偶见晶间孔”的特征,“微孔微喉”的孔喉结构特征抑制了储层物性的改善。实测物性数据表明目的层段砂岩属典型的超致密储层,运用“频率分布函数法”对比产气层和干层的物性,认为有效储层的物性下限是：孔隙度为3．5％,渗透率为0．053×10－3μm2。有效储层的分布受沉积环境、成岩作用和构造活动3方面共同控制,主控因素可以归结为“沉积主导、压实主控、胶结增密、溶蚀添孔、裂缝改渗”,压实作用和胶结作用通过减小孔隙空间及填充喉道对储层物性起破坏作用;溶蚀作用通过产生次生溶孔对储层物性起建设性作用;构造活动产生的微裂缝对储层渗透率起改善作用。纵向上,SQ3段处于储层次生孔隙发育带,是有利储层主要发育层段,SQ2次之;平面上,西部扇三角洲前缘亚相为最有利储层发育区,东部辫状河三角洲前缘亚相次之。     

Quartz and clinoenstatite exsolutions in clinopyroxene of garnet-pyroxenolite from the North Dabie Mountains, eastern China

The exsolution lamellae of quartz and clinoen-statite are idenfied in diopside of garnet-pyroxenolite from the North Dabie Mountain by transmission electron microscopy, which is interpreted that the lamellae are originally exsolved from a former ultra-high-pressure clinopyroxene due to decreasing of pressure. Study of petrography shows that there is compositional zoning hi the diopside itself. It is implied that the garnet-pyroxenolite had undergone intensive high-temperature granulite fades and high-amphibolitic fades retrogressive metamorphism, while the peridotite (the garnet-pyroxenolite's host rock) emplaced the crust     

河南洛阳马尾松树干液流昼夜变化特征及其影响因子分析

【目的】揭示马尾松(Pinus massoniana)在我国分布北界的树干液流昼夜特征及其与环境因子的关系,探索马尾松蒸腾耗水规律,为深入了解树木水分利用机制提供研究基础。【方法】以分布在河南洛阳的马尾松为研究对象,采用TDP热扩散探针和小型自动气象站对样地内的马尾松树干液流及周围环境因子进行连续监测,分析马尾松树干液流昼夜变化特征及其影响因子。【结果】(1)研究区马尾松树干液流速率呈昼高夜低的单峰曲线;马尾松存在夜间液流,零点前液流活动较零点后活跃。(2)6—10月的白天(太阳辐射大于5 W/m²)和夜间(太阳辐射小于5 W/m²)马尾松单株日均液流量为36.08 kg;夜均液流量为2.55 kg,占全天液流量的4.87%～9.27%;零点前液流量占夜间液流量的83.42%～95.54%。(3)马尾松树干液流速率与太阳辐射、饱和水汽压差(VPD)、温度、湿度、风速和降水量存在显著的相关性(P<0.05);太阳辐射是白天树干液流的最大影响因子,VPD是夜间树干液流的最大影响因子。【结论】在我国中西部地区相对干旱生境下,马尾松树干液流具有...     

Fluxes of carbon dioxide and methane from swamp and impact factors in Sanjiang Plain,China

Incomplete decomposition of organic matter results in the accumulation of the carbon and other nutriments in wetlands. The wetland ecosystem gains a large amount of carbon from atmosphere CO2 by photosynthesis, and it loses much of which back into the atmosphere as CO2 and CH4 emission through the decomposition and respiration. Climate change, such as global warming and reduction of precipitation could drive the wetlands from carbon sink to source[1,2]. Wetland plays an important role in car…     

新乡市近郊农田土壤重金属的生态风险评价

基于对新乡市近郊农田土壤的采样分析,利用潜在生态危害指数法及因子分析法,分析研究了土壤中重金属的潜在生态风险程度,内在关联性及其可能的污染来源.结果表明:土壤中重金属Cr与Cu的含量在国家土壤二级标准以内,而Cd,Ni与Zn含量明显超标;土壤重金属可能引起严重的综合生态风险,其中Cd,Ni的潜在生态风险等级分别隶属于极...     

Characteristics of climatic trends and correlation between pan-evaporation and environmental factors in the last 40 years over China

Using the data observed by 62 Chinese Routine Meteorological Stations (CRMS) with long term radiation observation, the climatic trends and the relationship between pan-evaporation and its environmental factors are analyzed comprehensively. The results show that during the last 40 years, the relative humidity is uptrend in west China, downtrend in east China, and their extrema are 0.20%/a and -0.22%/a respectively; the precipitations of about 61% CRMS keep uptrend, its maximum can reach 10.52 mm/a^2 while the cloud amounts of about 79% CRMS keep downtrend slightly. About 98% CRMS display the air temperature uptrend, and the maximum is 0.11℃/a. About 76% CRMSdisplay the land surface temperature uptrend. About 87% CRMS show the daily range of temperature downtrend. The global radiations observed by about 85% CRMS and the 10 m wind speeds observed by about 77% CRMS hold downtrend. The annual pan-evaporations of about 66% CRMS hold descend trend, and the biggest descent reaches -24.9 mm/a^2. The pan-evaporation has good relationship with many environmental factors, but the relationship with the relative humidity is the best. All of the climatic trends respond to the global climate changes.     

中国生态环境脆弱性及其评价研究进展

对近年来生态环境脆弱性的研究进行了归纳和总结，着重论述了脆弱生态环境的含义、生态脆弱性的成因及其评价方法，为脆弱生态环境的保护和管理实践提供借鉴．     

An in situ zircon Hf isotopic,U-Pb age and trace element study of banded granulite xenolith from Hannuoba basalt： Tracking the early evolution of the lower crust in the North China craton

Backscattered electron images, in situ Hf isotopes, U-Pb ages and trace elements of zircons in a banded granulite xenolith from Hannuoba basalt have been studied. The results show that the banded granulite is a sample derived from the early lower crust of the North China craton. It is difficult to explain the petrogenesis of the xenolith with a single process. Abundant information on several processes, however, is contained in the granulite. These processes in-clude the addition of mantle material, crustal remelting, metamorphic differentiation and the delamination of early lower crust. About 80% of zircons studied yield ages of 1842 ±40 Ma, except few ages of 3097-2824 Ma and 2489-2447 Ma. The zircons with ages older than 2447 Ma have high εHf (up to +18.3) and high Hf model age (2.5-2.6 Ga), indicating that the primitive materials of the granulite were derived mainly from a depleted mantle source in late Archean. Most εhf of the zircons with early Proterozoic U-Pb age vary around zero, but two have