基于SRTM-DEM和TM的流动沙丘提取方法研究

以塔克拉玛干沙漠的流动沙丘地貌为例,进行数字地貌形态提取方法研究。首先,利用高精度Srtm-DEM数据派生出坡度和起伏度两个地形因子数据,并参考坡度和起伏度的分类指标,实现沙地和沙丘边界线的自动提取,将风成地貌按照形态特征区分出沙地和沙丘两种地貌类型。其次,利用数学分析方法,根据斑块指数值的大小初步确定复合流动沙丘的类型。最后,基于高空间分辨率的遥感影像的色调、纹理、结构等特征,建立典型流动沙丘地貌特征的遥感影像特征图谱,依据遥感图谱进一步确定复合流动沙丘的类型,实现典型复合流动沙丘地貌形态和成因特征的计算机智能化提取方法。研究结果表明:该方法目前可以实现流动沙丘中的复合型链垄状沙丘、复合型沙垄、穹状沙丘和蜂窝状沙丘的智能化提取。     

祖厉河流域1:50 000与1:250 000比例尺DEM信息容量的比较

以甘肃省祖厉河流域为实验样区,以1:50 000 DEM为基准,运用比较分析与数理统计的方法,研究该区域 1:250 000 DEM描述地表形态的精度特征.基本技术平台为ArcGIS 8.3软件.研究结果表明,利用1:250 000 DEM所提取的流域各级河网、地面坡度、地面坡向3种因子与基于1:50 000 DEM 所提取的各因子相比较,均存在不同程度的信息损失,1:50 000 DEM能较好地模拟真实的地面信息.研究成果为半干旱区集水农业工程的规划和水土保持等应用标准的制定提供了理论依据.     

ANUDEM-专业化数字高程模型插值算法及其特点

基于已有地形图的数字化方式,通过内插方法建立数字高程模型,是迄今为止最为成熟和简单易行的DEM建立方法。ANUDEM是利用等高线、高程点和河流等数据插值建立DEM的专业化软件。该软件的基本算法由插值、数据平滑、地形强化等组成。软件具有自动诊断数据错误,客观地确定适应于插值基础数据精度的分辨率等特点,用其建立的DEM能正确反映地面水文地貌特征。初步应用研究表明,ANUDEM可应用于黄土高原并建立水文地貌关系正确的DEM,其质量较现有基于TIN方法建立的DEM有明显提高,能更好地描述地面的起伏和水文地貌关系。     

DEM内插算法对区域坡长提取的影响分析——以陕北黄土丘陵区为例

利用陕北黄土丘陵区10m分辨率的高程数据,在Visual Studio平台下,实现双线性内插、反距离加权内插以及移动曲面拟合这三种DEM内插算法,进而对不同的内插DEM采用多流向算法实现坡长提取,最后对不同内插DEM提取的坡长进行空间结构分析、坡长精度分析、栅格坡长值的空间统计分析以及不同分辨率下(10m,25m,50m)不同内插算法坡长提取的比较分析。分析结果表明:(1)移动曲面拟合内插DEM生成的栅格坡长表面可正确表达各层级径流线信息,并具有与原始DEM以及坡度图相同的空间结构特征即表面的光滑连续特性,且其坡长提取精度最高,是适用于陕北黄土丘陵区域坡长提取的DEM内插算法;(2)空间统计分析表明,在实验区域内,不同内插算法在坡长值较小区域有显著性差异;(3)不同分辨率比较分析表明,在陕北黄土丘陵区域,不同分辨率对不同内插DEM坡长提取无显著性影响,且验证了分辨率越低坡长提取值越大的规律。     

陕西关中地区植被指数变化多尺度分析

以关中地区遥感影像、数字高程(DEM)、地貌类型等资料为依据,运用地学信息图谱理论和方法,在RS和GIS的支持下生成关中地区1986-2007年NDVI变化图谱,并从栅格、地貌单元、坡度带及行政区划等多个尺度上,分析该区近22 a来NDVI的时空变化特征。研究表明：1986-2007年,关中地区年度NDVI]增加了20.91%,2000-2007年年均增幅约为1986-2000年的2.31倍;各地貌单元NDVI增幅表现为：黄土台塬＞黄土墚峁＞山地＞平原＞黄土塬;各坡度带NDVI]基本随坡度的增加而加大,且均呈增大态势;各地市年度NDVI增速为：渭南市>铜川市>宝鸡市>西安市>咸阳市。关中地区NDVI的时空变化是土地利用/覆被变化的结果,“退耕还林”政策的实施,促使了植被覆盖状况的改善。     

基于流域单元的黄土地貌正负地形因子量化关系模拟

正负地形是黄土高原地貌形态表达的重要参数,也是现代沟谷侵蚀和发育研究的重要切入点,对于流域形态发育的定量化描述有重要意义。文中以典型自然流域为基本单元,在沟谷发育明显的陕北-晋西-陇东地区选择86个样区,利用1:10000比例尺5m高分辨率DEM数据,提取样区内多视角刻画地貌形态的正负地形因子指标,并进行流域地貌形态特征分析;在此基础上采用数理统计与地理建模的方法,重点探讨正负地形因子间的关联性,进一步实现基于多因子的量化模型的构建,以揭示地形因子信息与流域沟谷发育的内在联系。结果表明,蚕食度(Y)与沟壑密度(X_1)、平均坡度差(X_2)及破碎度(X_3)能较好地刻画流域地貌发育形态,并存在着线性函数关系:Y=0.069*X_1-0.01*X_2+0.009*X_3+0.239,拟合度达0.868。该模拟方法在黄土地貌形态发育的研究中有着重要的理论意义,是数字地形模拟与信息挖掘的一次有益实践。     

面向子流域单元的典型黄土地貌分类研究

基于格网DEM的数字地貌形态类型自动划分是当前地貌研究的热点。根据基本分析单元的粒度大小,可将现有的分类方法划分为以栅格为分析单元和不规则坡面多边形为分析单元。然而,上述2种方法都无可避免地存在分类结果中地貌实体不完整性的问题。本文将分析单元提升至小流域级别,提出面向"细胞"级的微小尺度的子流域为分析对象的分类思想,利用GIS空间分析方法,构建子流域地理属性数据库,依据研究区已有的地貌资料,遴选出高程、起伏度、平均坡度、坡谱偏度4个核心分类指标,采用层次分类法,设定相应的地形因子阈值,将陕西省铜川市耀州区划分为:河漫滩、黄土残塬、黄土台塬、陡坡冲沟、墚峁状丘陵沟壑、石质小起伏平缓中山、石质小起伏陡峭中山以及水域等8大类型。分类结果最大程度保证了地貌实体的相对完整性,与用GPS进行的实地采样观测结果对比分析表明,该方案的分类精度达到88. 19%,可望成为基于面向子流域单元进行数字地貌分类研究的有益探索。     

近22年关中地区林草覆盖率时空动态研究

以关中地区遥感影像、数字高程、地貌类型等资料为依据,运用地学信息图谱理论和方法,在RS和GIS的支持下生成了关中地区1986～2007年林草覆盖率变化图谱,并从栅格、坡度带、地貌单元及行政区等多个尺度上分析了该区近二十二年来林草覆盖率的时空变化特征。研究表明:1986～2007年,关中地区林草覆盖率增加了15.25%,2000～2007年段增速约为1986～2000年段的2.60倍;各地貌单元林草覆盖率增幅表现为:山地>黄土梁峁>黄土塬>黄土台塬>平原;各坡度段的林草覆盖率增加,增速随坡度增大而加大;各地市林草覆盖率增速为:西安市>渭南市>咸阳市>铜川市>宝鸡市。研究区的林草植被覆盖率的时空变化特点是土地利用/覆被变化的结果,"退耕还林"政策的实施促使了该区林草覆被情况的改善。     

基于项目驱动的藉河流域土地利用时空变化动态分析

根据1997年、2001年和2005年三期TM影像资料,运用遥感非监督分类的方法提取土地利用信息.利用地理信息系统空间分析和数据统计的方法,分析藉河流域1997～2005年间土地利用数量变化和空间变化特征,研究该地区主要土地利用类型数量变化、空间变化以及在不同坡度的动态变化特征.结果表明:耕地、林地和草地三种主要土地利用类型占该研究区土地利用面积的97%以上,是该研究区主要的土地利用类型.以1997年为基数,到2001年和2005年耕地减少幅度分别为1.2%和11.1%,因此 1997～2001年的退耕程度小于2001～2005年;在不同坡度上,土地利用变化主要发生在5°～40°,而且在15°～25°之间变化最大.     

长春市土壤侵蚀潜在危险度分级及侵蚀背景的空间分析

在ARCGIS 8.3地理信息系统(GIS)支持下,实现了土壤侵蚀潜在危险的分级及其空间分析。首先,采用美国通用土壤侵蚀模型估算土壤侵蚀量,再用土壤年均侵蚀量、土层厚度和土壤容重得到土壤抗蚀年限图,按水利部标准将长春市土壤侵蚀潜在危险度分为五级,并提出了土壤侵蚀潜在危险指数的概念。借助GIS方法,通过分析不同坡度、不同坡向、不同地貌类型以及不同土地利用类型等背景条件下的土壤侵蚀潜在危险度情况,探讨了土壤侵蚀潜在危险度的空间分布特点。     

Dermestid beetles in ‘evolution Canyon’, lower Nahal Oren, Mt. Carmel, including new records for Israel

Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr _s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr _s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.     

Epidemiology of Toxigenic Fungi and their Associated Mycotoxins for Some Mediterranean Crops

Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.     

A survey of the genera of<Emphasis Type="Italic">Microgaster</Emphasis> latreille and<Emphasis Type="Italic">Hygroplitis</Emphasis> thomson (Hymenoptera: Braconidae: Microgastrinae) from China

The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.     

Plant Viruses Transmitted by Whiteflies

One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.     

Broad bean mottle virus in Morocco; curculionid vectors,and natural occurrence in food legumes other than faba bean (Vicia faba)

Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.     

The autumn leafroller: Phenology,damage and parasitoids in a Dutch apple orchard

The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.     

Diagnostics,genetic diversity and pathogenic variation of ascochyta blight of cool season food and feed legumes

Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.     

Characterization of Sclerotinia minor populations in Texas peanut fields

In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.     

Eyespot of Cereals Revisited: ITS phylogeny Reveals New Species Relationships

Four species so far classified in Pseudocercosporella or Ramulispora (hyphomycetes) are associated with eyespot disease symptoms of cereals. Two of these have been linked to teleomorphs that were described in Tapesia. Sequence data derived from the Internal Transcribed Spacer region (ITS1, 5.8S and ITS2) of the rDNA operon showed, however, that the eyespot fungi associated with Tapesia are not congeneric with Ramulispora sorghi, the type of Ramulispora. The genus name Tapesia is now rejected in favour of the conserved name Mollisia, which appears to comprise heterogeneous fungi. Tapesia yallundae is not closely related to the type of Mollisia, M. cinerea, but clusters separately, being more closely allied to species with Cadophora anamorphs. A new holomorph genus, Oculimacula, is therefore proposed for teleomorphs of the eyespot fungi, while the anamorphs are accommodated in Helgardia gen. nov.