晋北地区土地沙漠化经济损失初步研究

晋北地区地处我国北方农牧交错带,沙漠化是土地退化的主要表现形式。土地沙漠化经济损失估值是土地沙漠化研究的重要内容之一,是反映土地沙漠化及其危害程度的主要手段。采用灾害经济评价方法,分析和探讨了晋北地区土地沙漠化经济损失的估算步骤、估算内容、估算参数、估算过程等问题,并对晋北地区因土地沙漠化造成的经济损失进行了初步估算。结果表明:2008年晋北地区土地沙漠化造成的直接经济损失总计约为31.56亿元,占农业增加值的51.28%,间接经济损失预估在142.02亿元以上。     

西藏沙漠化程度及其分区评价

从区域沙漠化程度概念出发,本文依据西藏沙漠化普查和荒漠化监测所得的1991年与1997年两期土地沙漠化数据,选择沙漠化土地占地率、重度沙漠化土地占地率、沙漠化土地年增率、沙漠化土地年扩大面积占地率四个指标,采用多指标加权综合指数法,对西藏各个沙漠化县(市、区)的沙漠化现状程度等级进行了定性与定量兼有的评价,在此基础上对西藏沙漠化程度进行了区域概括与分区。评价结果,西藏65个沙漠化县(市、区)中有16个属于中度沙漠化程度,其余全部属于轻度,全区可划分出9个沙漠化程度区,其中轻度区4个、中度区5个,总体而言西藏土地沙漠化程度较轻。     

科尔沁沙地的土地利用与沙漠化

根据1985年和2000年的土地利用数据和从相同时期的TM影像上提取的土地沙漠化数据,运用ARC/INFO软件和Access统计软件,分析科尔沁沙地近20年来土地利用和沙漠化土地的构成及变化特点、土地利用与土地沙漠化之间的关系。主要结论草地和耕地是土地利用的主要类型,未利用地面积较大,其它利用类型面积较小;15年来,耕地和林地增加幅度最大,草地减少幅度最大,土地利用转移的主要方向是草地变为耕地和林地。科尔沁沙地沙漠化土地比例大,占一半左右,以中度类型为主;变化趋势是沙化面积增加,程度减轻。在持续强度利用条件下,面积广大的草地和耕地发生退化,由潜在沙漠化土地发展为轻度和中度为主的沙漠化土地;而土地利用方式变化所形成的沙漠化土地面积较小,在新增沙漠化土地中的比例亦很小。所以,草地、耕地等土地利用强度的增大是沙漠化土地面积扩大的最主要原因,而土地利用方式的改变能加快土地沙漠化的进程。     

艾比湖地区土地沙漠化遥感动态监测

基于RS和GIS技术,以1990年,2001年和2007年TM、ETM＋影像为信息源,建立目视解译标志,利用ENVI4.5和ARCGIS9.3的图像和数据处理功能,对艾比湖地区1990-2007年沙漠化动态变化进行了监测。结果表明：监测期内严重沙漠化和中度,重度沙漠化土地面积呈明显增加的趋势,轻度沙漠化土地减少。沙漠化...     

内蒙古阿拉善盟2000年土地沙漠化遥感监测

以阿拉善盟2000年TM卫星影像遥感信息为主要依据,根据中国北方土地沙漠化动态分类系统,在遥感影像上进行解译和面积量算,获得了阿拉善盟2000年土地沙漠化状况:沙漠化土地总面积3666232.9hm2,占土地总面积的15.48%。阿拉善盟主要的沙漠化类型为沙丘活化或流沙入侵(1846880hm2)、灌丛(草地)沙漠化(735369.5hm2)、砾质沙漠化(1064944hm2)和耕地沙漠化(19039hm2)。沙丘活化或流沙入侵主要分布在阿拉善左旗境内,巴丹吉林沙漠与腾格里沙漠和乌兰布和沙漠之间的一些低山丘陵和荒漠干草原上;灌丛(草地)沙漠化主要分布在阿拉善东部;砾质沙漠化主要分布在阿拉善盟的西部,尤其以额济纳旗最多;耕地沙漠化主要集中在额济纳绿洲。     

松嫩沙地荒漠化现状和原因

通过对松嫩沙地2000年的遥感监测表明:松嫩沙地共有盐渍化土地面积1613.17 km2和沙漠化土地面积3765.38km2,分别占整个沙地面积的3.13%和7.3%。盐渍化最严重的是大安,共有盐渍化土地894.19 km2,占到总盐渍化土地面积的55.43%;在沙漠化土地中,草场沙漠化土地3130.51 km2占沙漠化总面积的83.14%,耕地沙漠化土地634.87 km2占沙漠化土地总面积的16.86%。其中以轻度和中度沙漠化土地为主,分别占50.72%和36.81%,重度沙漠化土地占12.23%,严重沙漠化土地面积较少,仅占0.24%。土地沙漠化最严重的是大庆,占整个行政区域面积的19.15%,面积达到969.65km2。在文章的结尾,简要分析了松嫩沙地荒漠化发生的自然和人为原因。     

中国北方农牧交错带土地沙漠化成因与防治技术

对中国北方农牧交错带土地沙漠化的现状、成因及防治技术等问题进行分析，批北方农牧交错带是中国沙漠化发展最快、生态环境最脆弱的地区之一，其根本原因在于樵采、过牧、滥垦等人为活动过度。提出农牧交错带防治沙漠化的三大技术体系，即沙地植被恢复与固沙技术体系，农牧业集约化技术体系和区域农业优势资源开发与沙产业技术体系。     

锡林郭勒盟北五旗近5年沙漠化过程及成因分析

本文在收集前人研究成果和野外调查的基础上,运用RS和GIS技术,以2000和2005年具有相同时相(秋季)的两期TM影像为信息源,对锡林郭勒盟北部五个旗、市地区的沙漠化土地进行了动态监测和分析。研究结果表明:近5a来研究区土地沙漠化总体呈上升扩展的趋势,5a来沙漠化土地面积增加了1366.057km2,其中轻度、中度、重度沙漠化土地面积分别增加:239.806 km2、1025.393 km2、850.396 km2,与此相反严重沙漠化土地面积减少了749.539 km2;地表疏松的沙物质,为土地沙漠化发展提供了丰富的物质基础,不合理的人类活动加速了沙漠化的发展。     

中国北方春玉米干旱灾害风险评估

开展农业干旱灾害风险评估是实施干旱灾害风险管理、减轻旱灾损失和影响的必要途径,如何揭示成险因子变化及其相互作用是开展风险评估的关键。本文以中国北方春玉米为研究对象,利用我国北方各地春玉米产量和气象数据,以及地形、土地利用和土壤有效灌溉面积等数据,基于自然灾害风险评估原理,构建北方春玉米干旱灾害危险性指数,在地理信息系统(GIS)平台下结合春玉米种植的暴露度和其他影响抗灾能力因子对中国北方春玉米干旱灾害进行风险评估区划。结果表明,春玉米干旱较高或高风险地区主要位于内蒙古中部、宁夏、甘肃、辽宁西部和新疆部分地区,风险指标值在0.73以上;春玉米干旱较低或低风险地区主要位于黑龙江西南部、吉林中部、辽宁北部、河北南部和陕西中部等地区,风险指标值在0.72以下。该研究有助于深化认识风险评估中成险因子相互作用,研究结果对指导北方春玉米干旱灾害风险管理具有科学意义。     

“三北”防护林甘青宁类型区土地沙漠化遥感调查研究

本文是“七五”期间“三北”防护林甘青宁类型区土地沙漠化遥感调查成果总结。该区沙漠化土地面积为２５８７８．３７ｋｍ２，其中轻度、中度、重度和极度沙漠化土地分别为３０２０．３０ｋｍ２，７２７７．４４ｋｍ２、７０８５．５９ｋｍ２ｔ和８４９５．０４ｋｍ２．文中对沙漠化土地的分布及影响因素进行了分析，最后筛出合理的农林牧用地结构。     

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.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.