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1.
巴音布鲁克高寒草地主要植物种群生态特征分析   总被引：2，自引：0，他引：2  
本文采用Levins提出经Corwell修正指数和王氏重叠指数,在土壤pH值和土壤全盐二维生态因子梯度上,测定了巴音布鲁克高寒草地20种主要植物种群生态位宽度和生态位重叠值。结果表明,细果苔草、珠芽蓼、线叶嵩草、羊茅等建群种和优势种的生态位最宽,适应土壤酸碱和盐渍化能力强,为泛化种;委陵菜、千叶蓍、草原老鹳草等伴生种生态位窄,适应酸碱和盐渍化能力弱,为特化种。在二维资源维上生态位重叠值最高的种对发生在轮叶马先蒿和斜生秦艽之间,重叠值分别为0.7808和0.861,但其生态位宽度均很窄,未达到0.3。与较大的生态位宽度其生态位重叠值也较大的结论不完全相符。  相似文献   

2.
天山南坡高寒草地物种多样性及地上生物量研究   总被引：8，自引：0，他引：8  
在新疆天山巴音布鲁克草原对高寒草甸、高寒草原和高寒草甸化草原的物种多样性进行了研究,结果表明:盖度+高度指标测度群落物种多样性指数要优于盖度和株数指标,更适于测度高寒草地的物种多样性指数。丰富度指数、Margalef指数与Shannon-wiener指数相关性显著,在小的空间研究尺度内,草地植物群落物种多样性指数受丰富度指数的影响较大。地上生物量与丰富度指数、Margalef指数和Shannon-wiener指数呈负相关关系。  相似文献   

3.
巴音布鲁克高寒草地退化演替阶段植物群落特性研究   总被引：3，自引：0，他引：3  
以新疆天山南坡巴音布鲁克高寒草地为研究对象,通过主分量分析以及群落多样性指标,分析了不同退化演替阶段高寒草地植物群落特性变化规律。结果表明:以重要值为参数通过主分量分析(PCA)对样方进行排序,得到未退化、轻度退化、中度退化、重度退化4种类型群落;随着植物群落的逆行演替,优良牧草盖度、高度、频度等呈递减趋势,杂类草表现为增加趋势,植物群落物种多样性丧失。未退化阶段群落羊茅(Festuca ovina)、紫花针茅(Stipa purpurea)为优势种,随着退化加重,天山赖草(Leymus tianschanicus)、委陵菜(Ptentilla spp.)等在群落中占主导地位,地下芽根茎型草本植物逐渐代替地面芽密丛型禾草植物成为群落优势种。  相似文献   

4.
植被覆盖度和生产力指标作为评价草原生态系统退化已有较多研究,各单一评价指标互相独立难以对不同草原退化程度进行综合评价。本研究以新疆天山中部巴音布鲁克草原为研究对象,提出了一种基于标准化处理分指标耦合的草原退化遥感评估方法。选取草原植被覆盖度、草层平均高度、总产草量3个分指标,通过主成分分析法确定分指标权重,并引入Min-Max标准化方法处理并构建综合评价指标草地退化指数(Grassland Degradation Index,GDI),最终通过Landsat影像反演以及草地退化指数变化率的合理分级评估了1986—2021年新疆天山巴音布鲁克草原的退化程度。结果表明:(1)GDIg与NDVI的相关性最好。(2)2021年巴音布鲁克草原未退化面积占总面积的比例为60.51%;不同草地类型的草地退化程度有明显差异;空间分布上表现为由盆地向山地退化加重的趋势。(3)通过辐射配准方法可以将GDIrs模型应用于其他年份,2000—2009年巴音布鲁克草原退化程度明显改善,2009—2021年草原退化程度轻微波动。研究结果将为指导巴音布鲁克草原退化程度的评...  相似文献   

5.
不同干扰对高寒草原群落物种多样性和生物量的影响   总被引：14，自引：2，他引：12  
通过对新疆巴音布鲁克高寒草原天然草地进行灌溉、围栏(2年、7年、13年)和自由放牧处理,探讨不同干扰类型对草地植物多样性和生物量的影响。结果表明:灌溉使草地植物群落的高度、盖度和地上、地下生物量达到较高的水平,物种多样性也有一定程度的增加;而在自由放牧制度下,由于干扰过于剧烈,草地已呈退化趋势,物种多样性和生物量均较低;在围栏草地中,随着围封年限的增加,群落高度、盖度、地上、地下生物量逐渐增加,物种丰富度、多样性指数、均匀度指数呈现先增加后减小的趋势。在5种干扰类型中,物种丰富度、Shannon-W iener指数(H′)的排列顺序为:放牧草地<围栏2年草地<灌溉草地<围栏13年草地<围栏7年草地;P ielou均匀度指数的排列顺序为:围栏2年<放牧<灌溉<围栏13年<围栏7年;地上生物量的变化趋势为:放牧草地<围栏2年草地<围栏7年草地<围栏13年草地<灌溉草地;地下生物量的变化趋势为:放牧草地<围栏2年草地<灌溉草地<围栏7年草地<围栏13年草地。  相似文献   

6.
为探究东祁连山河谷高寒草地植被群落特征与土壤性状的关系,根据研究区河谷地形地貌及河谷高寒草地分布特征,选取了分布在河谷山地阳坡上部和下部、河谷山地阴坡上部和下部及河谷水平阶地的5类不同植被类型的高寒草地为研究对象。研究草地植被群落和土壤性状特征及相关关系。结果表明:河谷中不同坡向、坡位高寒草地植被群落优势种不同,河谷阳坡高寒草地以嵩草属植物为主,阴坡以蓼属植物为主;阴坡植被总盖度高,阳坡低;河谷阴坡下部草层高度最高,而水平阶地最小;植被群落总科数、总属数和总种数均表现为坡下部高于上部,阴坡高于阳坡;地上生物量依次为:阴坡下部>阳坡上部>阴坡上部>阳坡下部>水平阶地;0~60 cm土层地下生物量依次为:阴坡下部>阳坡下部>阴坡上部>水平阶地>阳坡上部。不同高寒草地土壤性状之间有显著差异(P<0.05)。相关分析表明,土壤含水量、容重、孔隙度和全氮等指标与植被总盖度、地上生物量、总科数、草地平均高度有显著的相关关系。可见,研究区河谷高寒草地植被与土壤之间的影响主要表现为土壤含水量、容重、孔隙度和全氮与植被总盖度、地上生物量、总科数、草地平均高度间的相互作用。  相似文献   

7.
围封条件下紫花针茅群落主要结构特征和地上生物量变化   总被引：2，自引：0，他引：2  
在新疆巴音布鲁克高寒草原,根据样方调查资料,通过测定围封22年后紫花针茅群落的特征值,并与围栏外作对照,就围栏封育对退化高寒草原植被特征的影响进行了分析。结果表明:对退化高寒草原实施长期的围栏封育,群落物种数目比围栏外增加23.77%;围栏内禾本科优良牧草比围栏外大量增加,杂类草较围栏外明显降低;群落物种多样性指数和均匀度指数均比围栏外减小;地上生物量较围栏外明显增加,其中禾本科牧草较围栏外增加66.46%。因此,从高寒草原生产利用角度看,构建围栏对于退化高寒草原的恢复和畜牧业的发展是有益的。  相似文献   

8.
土壤水分对毛乌素沙地油蒿群落演替的影响   总被引：2，自引：0，他引：2  
采用空间代替时间的方法,对毛乌素沙地三种不同演替阶段的油蒿(Artemisia ordosica)群落(半固定沙地油蒿群落、具生物结皮的油蒿群落、油蒿+本氏针茅群落)的群落特征及生物量、叶片气体交换过程、不同土层(0-10cm、10-20cm、20-40cm、40-60cm、60-80cm)土壤含水量、根系垂直分布等进行测定.结果表明:油蒿群落演替是油蒿与草本植物竞争、生物结皮发育、土壤发育以及土壤水分垂直变化等生物非生物因素综合作用的结果.随着油蒿群落演替的发展,群落物种数、草本层盖度和生物量、群落总盖度逐渐增加,而油蒿个体数、油蒿盖度、油蒿叶生物量以及生物土壤结皮盖度则先增加后减少,油蒿根系有向下分布的趋势,0-10cm土层逐渐以草本植物根系占优势.土壤水分是毛乌素沙地油蒿群落演替的主要驱动力,通过影响油蒿叶片气孔导度和净光合速率,以及根系垂直分布影响油蒿在群落中的竞争力.不同演替阶段油蒿群落土壤水分低值区不同,半固定沙地油蒿群落0-10cm和20-40cm土壤含水量最低,具生物结皮的油蒿群落10-20cm土壤含水量最低,而油蒿+本氏针茅群落60-80cm土壤含水量最低.  相似文献   

9.
植物群落养分的空间分布反映了生态系统物质循环特征,可以为揭示生态系统资源的有效性及生态系统中植物群落的演替过程提供依据。本研究以黄土高原农牧交错带退耕坡地苜蓿-铁杆蒿群落为对象,分析其生物量和养分含量的空间分布特征。结果表明:退耕地苜蓿-铁杆蒿群落坡上部以苜蓿为主导物种,坡下部以铁杆蒿为主导物种,坡中部由二者共同主导。同一植物的生物量和N含量具有相似的空间结构,并且与植物种类有关;苜蓿和铁杆蒿P含量均以球状模型最佳,K含量的空间分布均以高斯模型最佳。苜蓿-铁杆蒿群落生物量和养分含量具有较强的空间依赖性,其空间变异主要由结构性因素决定。苜蓿和铁杆蒿生物量和养分含量的自相关性随距离变化表现出相似的趋势,但随生物量和养分种类的不同而异,且铁杆蒿生物量和养分含量的自相关性大于苜蓿。随着人工草地向天然草地的演替,群落生物量和养分含量的空间自相关性和空间依赖性逐渐增强。  相似文献   

10.
文中对新疆伊犁河流域温性荒漠草地蒿类半灌木生物量随水分条件的变化规律进行了研究。结果显示:随着灌溉水量的增加,单位面积蒿类生物量明显表现出先增加然后下降的变化规律。据灵敏度(Sk)计算,灌溉水量在433kg/(m2.a)时,Sk存在最大值,表明此时地表生物量对灌溉水量变化的响应最为灵敏。根据灵敏度变化曲线将不同灌溉水量下地表生物量变化分为3个区间。灌溉水量在(226kg/(m2.a)—778kg/(m2.a))区间,蒿类生物量增加的幅度超过灌溉水量变化的幅度,实施此灌溉水量可得到最优恢复效果。因此恢复当地草地的合理水量范围确定在(226kg/(m2.a)—778kg/(m2.a))。从水资源利用的效率看,选择228kg/(m2.a)作为蒿类荒漠草地恢复的最小需水量更为合理。  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.
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   

19.
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.  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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