川藏公路迫隆藏布流域段泥石流活动特征

迫隆藏布流域是川藏公路 (西藏境内 )泥石流最活跃、类型最齐全、危害最严重的地区。根据以往资料、遥感普查以及现场考察 ,确定流域内公路两侧分布有灾害性泥石流沟 10 4条 ,其中沟谷型泥石流沟 87条。泥石流沟沟口高程在 2 5 0 0～ 3 5 0 0 m之间 ,流域面积介于 0 .8～ 185 km2之间 ,其中 83 .7%的流域面积在 1.0～ 4 0 .0 km2之间。按成因 ,泥石流可分为冰川型、溃决型、降雨型泥石流 ,其变化特性与泥石流流域的高程、降雨变化和地震活动密切相关。最后讨论了泥石流活动对地方经济发展的危害以及对当地山地环境的影响。     

基于RS和GIS的雅鲁藏布江林芝-加查段沿线泥石流源地物源分析

为研究泥石流灾害对西藏雅鲁藏布江林芝—加查段沿线的影响与危害,利用遥感(RS)和地理信息系统(GIS)开展了该段沿线泥石流源地物源提取及其分布特征的分析。研究结果表明,林芝—加查段沿线泥石流源地物源分布不均匀,物源分布受地层岩性、海拔高程及地形坡度影响。这些泥石流源地物源在冰川融水及冰川型泥石流过后更加发育,积累的松散物质更加丰富,使泥石流源地物源进一步复活并产生大量新物源,从而使沿线泥石流发生频率增高,规模增大。     

西藏林芝地区泥石流类型及形成条件分析

西藏林芝地区是我国泥石流灾害最为严重的地区之一,特别是近年来受全球气候变化的影响,冰川融化速度加快,冰川融水型泥石流灾害频频发生,危害极其严重。自2009年7月中旬开始,对该地区林芝、米林、波密、察隅4县30条泥石流沟做了系统调查。在研究该区域20条较具代表性泥石流沟的基础上,结合该区域已有研究资料,按泥石流形成的激发条件将其分为降雨型泥石流,冰川降雨型泥石流,冰崩、雪崩型泥石流,冰湖、堰塞湖溃决型泥石流共4类。进而从地形地貌、物源、水源及气温等方面分析了其形成条件。并在此基础上提出了针对性防灾建议。     

高寒高海拔山原区沟谷型泥石流成因与特征——以四川省雅江县祝桑景区为例

高寒高海拔山原地区沟谷型泥石流与深切峡谷地区泥石流具有较大差异性.以四川省雅江县祝桑景区泥石流为例,通过实地调查、测绘和泥石流堆积物样品颗粒分析,探讨了高寒高海拔山原地区沟谷型泥石流的成因和特征.研究表明:(1)强日照,大温差等气候条件导致高寒高海拔山原区物理风化作用强烈,土体松散,斜坡稳定性差,物源丰富,对泥石流的形成起到了重要的作用;(2)滑坡转化和沟底侵蚀构成物源补给与泥石流启动的主要方式;(3)泥石流动力条件相对较弱;(4)沟床纵坡曲线总体呈现出上游平缓,中游较陡,而下游至沟口进一步变陡的折线形态,汇水区和形成区分界明显,沟口至主河段平缓,堆积区较长;(5)泥石流堆积物粒度分布相对均匀.     

甘肃省长江流域的滑坡与泥石流

甘肃省长江流域是我国滑坡、泥石流高发区之一。严重的滑坡、泥石流,导致本区河道、水库淤积,生态环境恶化,人民生命财产受到巨大威胁。本文根据作用强度和物质组成,特区内滑坡、泥石流分为白龙江中游滑坡、泥石流严重作用区和西汉水中下游滑坡、泥石流严重作用区等七个区域,分析了地质、地貌、气候条件对滑坡、泥石流的影响,指出了人类活动在滑坡、泥石流发育过程中的作用,并提出了防治的对策。     

雅鲁藏布江流域地温变化与春麦种植上限的关系

雅鲁藏布江流域是西藏高原农业开发历史最悠久的地区。耕地面积,粮食总产占全西藏一半以上。春麦(春青稞、春小麦)是主要农作物,而且垂直地带分布十分明显,从河谷地区至海拔4750米的山地都能种植。农业生产的发展,急需了解热量条件对春麦栽培的影响。因此,阐明雅鲁藏布江流域气温或土温与春麦种植上限的关系,对开发西藏农业有着十分重要的意义。     

云南大桥河的泥石流拦挡坝

一、前言云南省东北部的小江流域,是我国泥石流暴发频繁,分布集中,类型齐全,危害严重的地区之一。大桥河是小江中游的一大支流,是一条粘性和稀性泥石流交替出现的大型泥石流沟。二三百年前,两岸曾是一片林木繁茂,流水潺潺,农舍棋布,稻菽飘香的好地方。由于泥石流的不     

金矿区矿渣型泥石流物源渗透特征研究

以黄河中游某金矿区为研究区,利用常水头渗透试验测定研究区矿渣型泥石流物源的渗透系数,结合颗粒筛分试验数据,与自然泥石流物源的渗透系数、颗粒级配进行对比,得出泥石流物源土体颗粒级配对渗透性能的影响,结论认为矿渣型泥石流物源的渗透性能与其他类型泥石流物源渗透性能的显著差异是控制研究区泥石流形成的重要因素。     

辽东地区泥石流雏议

近年来,辽东地区频繁发生泥石流活动,造成的水土流失,给辽东地区国民经济建设和人民财产安全带来严重威胁。据调查,泥石流活动主要发生在辽东地区的庄河、东沟、岫岩、宽甸、凤城、桓仁等县,特别是丹东地区泥石流活动更为强烈。     

金沙江流域云南段泥石流危险度评价

 为准确评价金沙江流域云南段的泥石流危险度,以行政区划为评价单位,选取金沙江流域43个县、市作为评价目标,运用层次分析法对8个评价指标的权重进行计算。在获取各评价单元基本资料的基础上,对各单元的8项指标进行分类和定量评分,求出各县、市泥石流危险度,最后在此基础上按照一定的标准对金沙江流域43个县、市的泥石流危险度进行评价。结果表明:金沙江流域云南段的上游和下游地区是泥石流危险度较高的地区,中游地区危险度相对较低。评价结果可为流域泥石流灾害的防治、土地规划及利用等提供科学的参考。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。