三维激光扫描提取DEM的地形及流域特征研究

以三维激光扫描系统为工具,建立黄土高原丘陵沟壑区绥德县桥沟小流域高精度DEM。在ArcGIS中将高精度DEM和该流域1:1万 DEM分别生成6种栅格大小不同的DEM图像。用2种精度、6种不同水平分辨率的DEM提取研究区的地形及流域特征,进行对比分析。结果表明:与1:1万 DEM相比,高精度DEM提取出的研究区流域面积变小,平均坡度、平均高度、沟壑密度增大,河网密度、河道坡度增大,能够更加详细、准确地描述研究区的地形及流域特征,对流域水文过程分析以及水土保持研究起到积极作用。     

基于DEM的马莲河流域数字地形分析

研究基于DEM的数字地形分析可以为各个领域提供地形分析的基础理论及实现手段。DEM水平分辨率作为重要的尺度参数,是确定地形参数和应用尺度的重要指标。选取陇东黄土高原地区的马莲河流域作为研究对象,应用美国ESRI公司开发的ArcGIS地理信息系统软件,基于数字高程模型进行流域地形特征的提取与分析。研究提取流域的基本地形特征如坡度和坡向,提取流域水系,划分了小流域。通过分析比较,得出DEM水平分辨率对提取的地形特征及水文特征的影响,为马莲河流域的数字地形分析提供了理论依据。     

DEM水平分辨率对流域特征提取的影响分析

在基于数字高程模型（DEM）的流域地形分析中,栅格DEM的分辨率对分析结果具有很大的影响。以舒城县内面积为7.9 km²的龙潭小流域作为研究区域,分别对分辨率为5 m×;5 m～50 m×;50 m的10幅DEM数据进行流域特征提取和分析,计算地形指数并分析其分布特征。研究表明:在小流域尺度上,DEM分辨率的变化对流域面积、最长河道长度等参数影响不大,对河道总长度、河网密度及平均坡度等参数有较大影响,对流域特征的提取影响规律为DEM分辨率越低,提取的流域特征越粗糙;且分辨率低于15 m的DEM计算出的地形指数值较为离散、概率分布曲线形状较之5 m分辨率DEM的地形指数概率分布曲线有明显不同,表明分辨率低于15 m的DEM对小流域水文地形信息的反映较差,为小流域尺度水文模型DEM数据适宜分辨率选取提供一定的理论依据。     

黄土丘陵沟壑区不同数据结构DEM转换精度研究

栅格DEM与TIN是DEM表面建模主要的2种方法。应用DEM进行地形分析时,栅格DEM与TIN的相互转换非常必要,但在转换中所产生的误差直接或间接地影响到分析结果的准确性。以陕北黄土丘陵沟壑区的绥德县韭园沟流域为实验区,采用高精度的1:1万DEM为基准数据,探讨不同转换参数对转换精度的影响。实验结果表明,所建立的栅格DEM表面高程误差随着TIN的转换阈值的增大而增大、所提取的地面坡度、沟壑密度的精度随之降低。TIN的转换阈值以5 m为较为理想的指标。     

基于四种分辨率DEM的侵蚀模型地形因子差异分析

通过提取江西省兴国县潋水河流域10 m、25 m、50 m和100 m四种分辨率数字高程模型(DEM,Digital Elevation Model)的坡度、坡长因子,在GIS数字地形分析和数理分析等方法支持下,研究不同分辨率DEM计算坡度坡长组合因子(LS)的精度差异。结果表明:(1)基于4种分辨率DEM提取的坡度结果存在明显差异,随分辨率的降低,坡度整体变缓,DEM精度越低,对地形的概括作用越大,100 m分辨率DEM平均坡度降为10m分辨率DEM平均坡度的45.04%。(2)流域坡长以0~80 m的短坡为主,随着分辨率的降低,地面坡长明显整体延伸。(3)不同分辨率DEM计算的LS因子平均值变化范围为6.10~7.10,坡度和坡长的组合消弱了单一坡度和坡长的影响,随着地形起伏程度增大,在LS因子计算过程中,坡度的主导作用越来越弱,坡长的主导作用越来越强。     

黄土丘陵沟壑区1∶1万及1∶5万比例尺DEM地形信息容量对比

黄土丘陵沟壑区地形变化异常复杂 ,1∶5万地形图对原始 1∶1万地形图等高线形态综合、取舍程度很大 ,这些都在不同程度上影响了地形分析结果的准确性。以高精度的 1∶1万比例尺DEM为校准值 ,运用 1∶1万及 1∶5万比例尺DEM叠合比较分析的方法 ,研究 1∶5万DEM的地形信息容量及提取不同地形要素的精度。试验结果表明 ,在黄土丘陵区 ,与 1∶1万DEM相比 ,1∶5万DEM在所提取的地面坡度、地面曲率、沟壑量等地形定量指标方面均都存在着较大的误差。     

黄土丘陵沟壑区1∶1万及1∶5万比例尺DEM地形信息容量对比

黄土丘陵沟壑区地形变化异常复杂，1：5万地形图对原始1：1万地形图等高线形态综合、取舍程度很大，这些都在不同程度上影响了地形分析结果的准确性。以高精度的1：1万比例尺DEM为校准植，运用1：1万及1：5万比例尺DEM叠合比较分析的方法，研究1：5万DEM的地形信息容量及提取不同地形要素的精度。试验结果表明，在黄土丘陵区，与1：1万DEM相比，1：5万DEM在所提取的地面坡度、地面曲率、沟壑量等地形定量指标方面均都存在着较大的误差。     

基于DEM的流域降雨径流模拟研究--以三峡库区晏家河小流域为例

DEM是目前用于流域地形分析的主要数据,在流域地形分析及水系构建等方面形成了比较成熟的算法。基于DEM的水文模拟技术的应用给传统的水文模拟方法带来了根本性的变化。以三峡库区晏家河小流域为例,应用最新引进的WMS专业水文处理软件,结合Arc/Info,ArcView地理信息系统工具,在1∶1万DEM基础上生成河网水系,确定流域边界并进行子流域的划分。在生成数字流域的基础上,采用WMS嵌入的HEC-1模型进行降雨径流模拟研究。     

不同比例尺DEM提取地面坡度的精度研究——以在黄土丘陵沟壑区的试验为例

以陕北绥德县韭园沟流域为试验样区 ,采用高精度 1∶ 1万 DEM所提取的坡度为准值 ,应用多层面复合分析和比较分析的方法 ,研究该地区 1∶ 5万 DEM提取地面坡度的误差特征与纠正方法。试验结果显示 ,所获得的不同空间尺度下 DEM所提取坡度值的转换图谱 ,可对 1∶ 5万 DEM计算的地面坡度统计值进行有效修正。该成果对于 DEM数据在水土保持领域若干应用标准的制定 ,提供了重要的理论依据与技术路线     

水文地貌关系正确DEM的建立方法

 水文地貌关系正确DEM(hydrologically correct DEMs,Hc-DEM),是指符合水文地貌学基本原理,正确反映水文要素(水流方向、水流路径、水系网络、流域界线等)与地貌特征发生和位置关系的DEM。区域尺度水文和土壤侵蚀等研究中,地形因子参数只能利用DEM来提取,为了准确反映地面形态,有效提取地貌和水文特征因子,建立Hc-DEM是必需的。笔者对Hc-DEM的概念、建立方法进行了讨论和介绍;以黄土高原为例,提出了利用多种比例尺数字地形图和ANUDEM软件建立DEM的关键参数;通过与TIN方法建立的DEM的比较,对所建立的DEM进行了简要评价。研究表明,利用我国已有的数字地形图和ANUDEM软件,可以建立Hc-DEM,为流域水文和区域尺度水土流失定量分析模拟、区域尺度植被适宜性评价等研究提供更加直接的数据支持。     

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.     

“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。     

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.     

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

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.