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1.
运用气候变率、线性回归、因子相关分析等方法,对1975-2005年陕北农牧交错区降水、温度变化进行分析,得出气候暖干化趋势显著的结论。对土地、水和粮食安全与干旱化相关系数离散程度分析表明:在气候干旱化作用和煤炭资源过量开发影响下,区域生态环境退化严重;以无定河、延河流域为例,发现流域年降水量每增加10%,其径流量增加22.22%,径流深度加深4.47%,年降水量每减少10%,径流量减少15.98%,径流深度减少3.56%的规律;粮食、牧草受暖干化影响,需水胁迫加剧,出现了产量降低,品质下降,草场承载力下降等问题;最后,针对土地、水和粮食安全对干旱化的响应,提出了适应性对策。  相似文献   

2.
青藏高原东北部边坡地带气温变化特征研究   总被引:2,自引:0,他引:2  
利用青藏高原东北部边坡地带12个地面气象站1961~2000年的月平均气温资料,分析了40年来气温变化的特征及趋势.发现,青藏高原东北部边坡地带气温暖突变发生在1987年,从20世纪80年代初开始区域内最低气温明显上升,到90年代出现最高、最低气温同时上升的现象;夏季、秋季和冬季平均气温普遍呈升高趋势,冬季气温在1978年出现暖突变,升温趋势明显要大于其它季节,春季气温上升趋势不明显.最高、最低气温和气温日较差的变化具有明显的季节差异.  相似文献   

3.
为了对青藏高原东北部边坡地带潜在蒸散量和地表湿润度的变化进行研究,利用甘肃省合作市气象站1961~2010年的地面气象观测资料,根据Penman-Monteith模型计算了合作地区草地潜在蒸散量,发现合作地区年潜在蒸散量呈明显上升的趋势,上升趋势为13.0mm/10a;地表湿润度以-0.02/10a的趋势减小,出现了明显的暖干化趋势。温度升高和相对湿度下降是造成合作地区草地潜在蒸散量上升的主要气候影响因子,同时日照时数增加、降水量减少和风速增大对合作地区草地潜在蒸散量上升也有重要影响。  相似文献   

4.
通过对研究区81个气象站1981~2010年的气象资料和收集的草原火灾资料统计分析,得出内蒙古草原区年平均气温呈直线上升趋势,增温率为0.337℃·10a-1;年降水量呈减少趋势,1999年以后年降水量减少40.8mm;多年平均风速呈减小趋势;气候经历了冷干-暖湿-暖干期。受气候暖干化的影响,内蒙古草原植被退化,牧草高度、盖度和地上生物量降低,地面可燃物载量也降低,使草原火灾呈逐年递减趋势。引发草原火灾的火源雷击火和境外火明显减少,机车失火和吸烟引发的火灾仍高居榜首。从地域分布上看,内蒙古东北部草原火灾的次数在减少;西部地区受降水增多和国家实施的生态建设工程的影响,部分地区植被得到恢复,地面可燃物增多,草原火灾呈上升趋势。风速减小,牧草的及时刈割,牧区的科学管理和牧民防火意识的提高,是近几年没有重特大草原火灾发生的主要原因。  相似文献   

5.
通过利用Holdridge可能蒸散率(PER),对玛曲草地1971~2010年的干湿变化特征进行了分析,近40年玛曲草地PER呈明显的上升趋势,上升趋势达0.03/10a,20世纪90年代后,玛曲草地PER持续偏高,并在1993年出现了增大突变,降水量以7.4mm/10a的趋势减少,温度以0.46℃/10a的趋势上升,生物温度以0.25℃/10a的趋势上升,降水量与生物温度呈现出明显反向变化,玛曲草地有从极湿润区向湿润区过渡的趋势,出现了明显的暖干化趋势。主成分分析表明玛曲草地暖干化的主要原因是气温升高,同时日照时数增加、降水量减少、相对湿度下降和风速减小加剧了暖干化的趋势。受气候暖干化和人为因素的影响,玛曲草地出现了明显的退化和沙化,沼泽湿地的面积也呈明显的减少趋势,导致玛曲草地牧草产量下降,涵养水源能力急剧下降和生物多样性锐减。  相似文献   

6.
1960-2009年大连市气候暖干化研究   总被引:2,自引:0,他引:2  
利用大连市1960-2009年气温和降水两个主要气象要素值的基本观测资料,运用线性倾向估计和GIS空间分析方法,探讨了大连气候的年际时空变化,同时利用Mann-Kendall统计检验和Morlet小波分析对其气候的年代际和周期性变化进行了分析。结果表明:近50a来大连市气候暖干化日趋明显,年平均气温以0.28℃/10a的速率显著上升,并且在1991年发生突变进入异常增暖期,空间上增暖趋势大致呈由南向东北逐渐减弱的态势;降水量基本经历了"减少-增加-减少-增加"的变化过程,总体上呈下降趋势,在1972年降水量由偏多向偏少转变,东北和西南地区降幅较大,腹地最小。此外,气候的暖干化趋势对"自然-社会-经济"复合系统造成的影响应引起重视。  相似文献   

7.
1957-2007年额济纳荒漠绿洲暖干化趋势   总被引:2,自引:0,他引:2  
选用1957-2007年额济纳旗气温、降水、相对湿度等资料,使用距平分析、趋势分析、累计距平、滑动t检验、Yamamoto等方法,分析额济纳旗51年来的气温、降水、相对湿度、干燥度等变化趋势以及干燥度的突变特征.结果表明:51年来额济纳旗年、季平均气温均明显上升,年降水量及夏季降水量呈明显下降趋势,干燥度亦呈逐渐下降趋势,气候暖干化趋势明显,干燥度在1989年发生了突变.在西北部分地区出现暖湿化趋势,额济纳旗则呈现明显的暖千化趋势,在气候暖干化趋势下,额济纳旗环境无疑将承受更大压力,在追求经济快速发展的同时,应考虑气候的暖干化趋势,从而制定科学的环境保护政策.  相似文献   

8.
北方农牧交错带干旱灾害及其对暖干气候的响应   总被引:1,自引:0,他引:1  
利用1961 ~2012年气象数据资料,采用线性回归、反距离加权空间插值(IDW)对北方农牧交错带气温、降水气候要素的时间演变特征进行了分析,并在此基础上运用Is指数和Modet小波变换等方法研究该区域的干旱状况.结果显示:近52年来,北方农牧交错带气温增温速率为0.32℃/10a,降水量减少速率为7.35mm/10a,气候暖干化趋势明显;气候暖干化导致该区干旱灾害的发生频率增加、强度加剧;干旱灾害主要存在7a和8a的年际变化周期,1989年以前气候偏湿润,1989年以后干旱严重;干旱灾害发生频率最高的是西北段部分,西北段和东北段偏旱与大旱严重,而华北段重旱严峻.  相似文献   

9.
利用53个气象观测站1961—2017年5—9月逐日降水资料,分析了青藏高原东北部雨季降水量的变化特征,以及不同等级降水变化在降水量增量中的相对贡献。结果表明:1961—2017年青藏高原东北部干旱区雨季降水量呈增加趋势,半干旱区和半湿润区降水量的极端性增强。大部分地区的降水强度普遍增加。进一步分析可知,青藏高原东北部雨季降水量变化主要由降水强度的变化引起,同时中雨等级降水增加贡献大于其他等级降水。半湿润区和半干旱区东部降水极端化趋势明显增强。该结果有助于进一步理解和认识青藏高原东北部生态环境变化的气候效应。  相似文献   

10.
甘肃省雨养农业区气候变暖背景下秋粮生产脆弱性研究   总被引:7,自引:0,他引:7  
利用甘肃省雨养农业区4个地(市)31个县近40 a的秋粮产量和气候资料,分析了这几个区域40 a来的气候变化特征、产量演变规律,并对秋粮生产的脆弱性进行了评价。结果表明,近40 a来甘肃雨养农业区的气候表现为暖干化演变趋势;气候的暖干趋势对秋粮的增产不利,气候的暖干化减缓了粮食的增产速度;气候波动剧烈的地区秋粮生产的脆弱度大。强脆弱区主要集中在陇东东部及天水北部地区。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
Plant Viruses Transmitted by Whiteflies   总被引:18,自引:0,他引:18  
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.  相似文献   

15.
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.  相似文献   

16.
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 PVYN strain and six to the PVYO strain. No PVYC was found. Two other isolates reacted serologically like PVYO, but were unable to elicit a hypersensitive response from the Nytbr gene and probably represent the PVYZ group. At the molecular level, these two isolates showed a combination of both PVYO and PVYN and could be recombinants of these strains. Another isolate reacted serologically like PVYO, but induced vein necrosis in tobacco, like PVYN-Wilga. Some PVYN isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVYNTN group. The PVYNTN, PVYN-Wilga and PVYZ groups probably represent pathotypes within strains PVYN and PVYO, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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