社会资本与年轻牧民草地租赁行为

由于没有赶上草场承包,加上非牧就业的困难,占总牧户数近四分之一的年轻牧户将租赁作为获取土地维持生计的重要途径。然而,与年长牧民相比,年轻牧民面临更高租赁价格从而更难于租到土地。文中采用内蒙古呼伦贝尔和锡林郭勒12个纯牧业旗422个牧户的实地调研数据,运用计量分析方法,探讨了社会资本对年轻牧民租赁草地的影响。研究发现,社会资本能显著提高整体牧户的草地租赁,但对年轻牧户的影响要显著弱于年长牧户。社会资本的代际差异是导致这一结果的主要原因。鼓励年轻牧户更多参与社区事务、获取信息和赢得信任,从而降低草地租赁门槛成为年轻牧民获取生计途径、促进牧业可持续发展和牧区社会和谐稳定的关键。     

基于环境规制视角下牧户风险感知对亲环境行为的影响研究——以三江源地区为例

牧户亲环境行为是实现三江源地区生态经济社会可持续发展的根本保证。文中以三江源地区牧户为调研对象,使用多元有序Logistic模型,实证分析牧户风险感知对亲环境行为的影响,同时引入环境规制作为调节变量,探究环境规制在牧户风险感知与亲环境行为关系中的调节效应。研究表明：1)牧户风险感知对亲环境行为有显著的正向影响,其中,环境风险感知对亲环境行为的影响更加显著。2)环境规制对牧户风险感知与亲环境行为之间的关系起到正向调节作用,且约束型、引导型和激励型规制均能正向调节牧户风险感知与亲环境行为之间的关系。据此,文中从提升风险感知水平和健全环境规制制度两方面提出对策建议。     

草原生态补奖政策对牧户生计脆弱性的影响——来自青海省河南蒙古自治县牧户的经验分析

草原生态补奖政策自实施以来，对我国牧户生产生活形成重要影响。作为面向牧户生计最重要的政策之一，科学评价现有草原生态补奖政策对牧户生计脆弱性的影响，并探究如何实现草原生态补奖政策与牧户生计脆弱性之间的良性发展，具有必要性和现实意义。文中基于OLS模型，使用青海省河南蒙古自治县304户牧户的微观调研数据，以综合测度牧户生计脆弱性指数为基础，实证检验了草原生态补奖政策对牧户生计脆弱性的影响，并运用分位数回归模型和渠道效应模型进一步探究这一影响的异质性与作用机制。研究发现：1)草原生态补奖政策对牧户生计脆弱性存在显著正向影响。2)草原生态补奖政策对不同生计脆弱性牧户的影响存在一定的异质性，草原生态补奖政策主要对低生计脆弱性牧户有显著的影响，而对中高脆弱性牧户影响不显著。3)渠道效应机制分析表明，生态冲击性、收入多样性和可持续动能在草原生态补奖政策与牧户生计脆弱性之间发挥着重要作用。因此，未来有必要通过降低牧户生态冲击性、提升收入多样性和增强牧户可持续动能推动草原生态补奖政策实施，并针对不同群体采取差别化的草原生态补奖政策，进行促进草原生态补奖政策效应的发挥。     

新疆参与旅游业牧民生计资本研究——以喀纳斯和乌鲁木齐县南山生态旅游区为例

农牧民生计资本是可持续生计研究框架的基础,决定了农牧民家庭生计策略的选择与结果。文中运用问卷调查与入户访谈相结合的方法,开展了新疆生态旅游发展典型区域内参与旅游业牧民生计资本的实证研究。通过采用计算赋值与标准化的数据预处理方法,借助社会统计软件工具,对样本牧民的生计资本水平进行了比较研究。结果发现样本生计资本总值仅为0.249,处于较低水平状态,其中物质资本水平最低,人力资本水平最高;不同生计资本水平的牧民分布很不均衡,自然资本和物质资本在0.2以下水平的牧民累积百分比分别为52.7%和79.1%;牧民家庭特征中家庭人口数最多的牧户生计资本总值最低,民族及调查区域的生计资本水平差异不大。     

草原补奖是否促进了牧户增收与收入多样化?——基于青海省微观调研数据

草原补奖政策兼具恢复草原生态环境与促进牧民增收双重目标。文中以青海省共和县牧户微观调研数据为基础，应用多元线性回归模型和多元有序Logit模型，评估草原补奖政策参与对牧户收入水平与结构的影响及其异质性。研究结果表明：草原补奖有效促进了牧户增收，且该促进作用随着牧户收入水平的提高而增强；补奖政策参与反而抑制了牧户收入来源多样化，拥有较大承包草地面积的牧户获得更多的补奖，继而将其用于扩大畜牧业生产，降低了牧户选择多样化生计策略的积极性，与该补偿政策实施初衷相悖。     

草原确权是否提高了牧民产权安全认知?——基于不同类型牧户的异质性分析

草原确权作为稳定草原产权的正式制度安排,对激励牧民生产性投资、促进草地流转,实现草原可持续利用具有重要意义.牧民的产权认知受当前确权环境和以往产权经历的影响而不同,文章采用多分类有序Logit模型,探究基于不同类型牧户异质性视角下的草原确权对牧民产权安全认知的影响.结果 表明:1)区域内,已完成草原确权颁证的牧户占87...     

牧民草地生态保护认知与行为的实证分析——基于西藏75个自然村的实证分析

依据拉萨、那曲及林芝地区牧民入户调查资料,对西藏牧民草地退化的认知及其放牧行为进行深入分析,揭示牧民草地资源保护诉求与草地资源利用倾向。分析结果表明:牧民对草地资源退化已经形成共识;牧民具有草地保护认知,但草地退化原因大多归因于政府保护不力,较少考虑养殖规模的影响;面对日益恶化的草地资源,牧民仍有扩大养殖规模趋势。     

生计资本对牧民减畜意愿的影响分析—基于内蒙古372户牧民的微观实证

基于内蒙古372户牧民的抽样调查数据,采用熵值法评估了牧民生计资本状况,随后检验了生计资本对牧民减畜意愿的影响。结果表明:1)牧民生计主要依靠人力资本和金融资本,其次是社会资本和物质资本,最后是自然资本。2)生计资本中社会资本、物质资本、人力资本和金融资本能显著促进牧民减畜意愿,自然资本则反之。其中,社会资本中的社会网络和参与集体活动情况、物质资本中的牲畜数量、人力资本中的劳动力数量、金融资本中的家庭现金收入均能显著促进牧民减畜意愿,自然资本中的草场面积和草地质量能显著抑制牧民减畜意愿。     

新疆草地生态安全问题、现状与对策分析

简要介绍新疆草地生态问题的由来及现状，运用新的生态安全理论分析新疆草地生态安全时空特征，指出新疆草地生态安全问题是长期人地矛盾不断尖锐与发展演变而来。人口膨胀引起的资源环境破坏、超载过牧造成对资源的掠夺经营等，使草地稳定自协调机制破坏，草地自然生态系统由稳定走向严重危机，并引发新的牧业危机。分析指出，实现人地关系的和谐，需综合考虑生态、经济、社会历史等方面的因素。其中，绿洲区牧民定居点的综合发展水平是维护草地生态安全、实现牧业可持续发展的关键。实现生态安全与可持续发展的主要对策有：依法监理草地放牧状况、合理利用、改良与保护天然草地、高效经营人工草料基地、提高畜牧业经营水平等。依托的关键技术有：草地资源监测技术、退化草地治理及草地利用实用技术等。     

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.     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

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.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

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.     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

The use of Solacol® (validamycin) as a growth retardant in the isolation of soil fungi

Solacol^®, a formulation of the antibiotic validamycin, at 0.33% in 2% malt extract agar, reduced the spread of fungi on dilution plates drastically and allowed twice as much incubation time before subculturing; this resulted in an elevated number of species isolated. Using pure cultures of 62 common soil fungi, it was shown that all fast-growing species (exceptPythium ultimum) were efficiently inhibited but not completely suppressed. Inhibition was comparable to that by 0.5% oxgall, though, while this substance completely suppressed several species, Solacol very strongly inhibited onlyGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum andRhizoctonia solani. In a further experiment each separate constituent of Solacol was tested against 22 fungi at equivalent concentrations. Validamycin strongly inhibitedChaetomium globosum and two Basidiomycetes, though hardly more than the non-ionic detergent which mainly inhibited the other fungi. A few species were, however, more inhibited by Solacol than by the detergent alone. Solacol at 0.33% is a suitable aid in dilution plating of soil fungi, by increasing the number of colonies and species observed.Samenvatting Solacol^®, een formulering van het antibioticum validamycine, remde de groei van schimmels in verdunningsplaten met een concentratie van 0.33% in 2% moutagar en maakte het mogelijk de periode tot afenten met een factor 2 te verlengen; daardoor was het aantal geïsoleerde soorten duidelijk toegenomen. Met reincultures van 62 algemene grondschimmelsoorten werd aangetoond, dat alle snelgroeiende soorten (met uitzondering vanPythium ultimum) voldoende geremd, maar niet volkomen onderdrukt werden. Het remmingspercentage was vergelijkbaar met dat van 0.5% ossegal, hoewel dit laatste sommige soorten volkomen onderdrukte; Solacol remde alleenGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum enRhizoctonia solani zeer sterk. In een volgend experiment werden de componenten van Solacol t.o.v. 22 fungi apart getoetst in concentraties equivalent aan 0.33% Solacol. Validamycine remde alleenChaetomium globosum en twee basidiomyceten behoorlijk, maar nauwelijks meer dan de niet-ionische uitvloeier, die in hoofdzaak de overige remeffecten veroorzaakte. Enkele soorten werden echter door het complete Solacol veel sterker geremd dan door de uitvloeier alleen. Solacol in een verdunning van 0,33% wordt aanbevolen bij verdunningsplaten voor het isoleren van grondschimmels ten einde het aantal kolonies en soorten te verhogen.