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41.
Dominance of non-native riparian trees in western USA 总被引:1,自引:0,他引:1
Jonathan?M.?FriedmanEmail author Gregor?T.?Auble Patrick?B.?Shafroth Michael?L.?Scott Michael?F.?Merigliano Michael?D.?Freehling Eleanor?R.?Griffin 《Biological invasions》2005,7(4):747-751
Concern about spread of non-native riparian trees in the western USA has led to Congressional proposals to accelerate control efforts. Debate over these proposals is frustrated by limited knowledge of non-native species distribution and abundance. We measured abundance of 44 riparian woody plants at 475 randomly selected stream gaging stations in 17 western states. Our sample indicates that Tamarix ramosissima and Elaeagnus angustifolia are already the third and fourth most frequently occurring woody riparian plants in the region. Although many species of Tamarix have been reported in the region, T. ramosissima (here including T. chinensis and hybrids) is by far the most abundant. The frequency of occurrence of T. ramosissima has a strong positive relation with the mean annual minimum temperature, which is consistent with hypothesized frost sensitivity. In contrast the frequency of occurrence of E. angustifolia decreases with increasing minimum temperatures. Based on mean normalized cover, T. ramosissima and E. angustifolia are the second and fifth most dominant woody riparian species in the western USA. The dominance of T. ramosissima has been suspected for decades; the regional ascendance of E. angustifolia, however, has not previously been reported. 相似文献
42.
Gtari M Brusetti L Skander G Mora D Boudabous A Daffonchio D 《FEMS microbiology letters》2004,235(2):349-355
The occurrence and diversity of Frankia nodulating Elaeagnus angustifolia in Tunisia were evaluated in 30 soils from different regions by a Frankia-capturing assay. Despite the absence of actinorhizal plants in 24 of the 30 soils, nodules were captured from all the samples. Eight pure strains were isolated from single colonies grown in agar medium. On the basis of 16S rRNA and GlnII sequences, seven strains were clustered with Frankia, colonizing Elaeagnaceae and Rhamnaceae in two different phylogenetic groups while one strain described a new lineage in the Frankia assemblage, indicating that Frankia strains genetically diverse from previously known Elaeagnus-infective strains are present in tunisian soils. Genomic fingerprinting determined by rep-PCR, and tDNA-PCR-SSCP, confirmed the wide genetic diversity of the strains. 相似文献
43.
Abstract: Restriction fragment length polymorphism (RFLP) analysis of the PCR amplified nif D-K intergenic spacer (IGS) region was used to cluster 22 Frankia strains of the Elaeagnus host specificity group into seven genomic groups and to measure the degree of genetic similarity among them. This PCR-RFLP analysis could assign freshly isolated strains to described genomic species and revealed genomic groups not yet described among Frankia strains of the Elaeagnus specificity group. Six broad-host-range Frankia strains, infective on both Alnus and Elaeagnus , fell into three closely related PCR-RFLP clusters. DNA-DNA hybridization was then used to establish the correlations between PCR-RFLP clusters and total DNA relatedness groups. The three PCR-RFLP clusters agreed with two new and one reference genomic species, indicating that Frankia ability to nodulate with Alnus and Elaeagnus is a monophyletic trait shared by three genomic species. 相似文献
44.
濒危植物翅果油树种群传粉生物学研究 总被引:2,自引:0,他引:2
对山西省南部平陆、乡宁和翼城3个翅果油树(Elaeagnus mollisDiels)种群分别进行了传粉生物学观察.结果表明:(1)翅果油树花期一般为8~12 d,单花花期3~4 d,结实率仅为0.42%;(2)访花者多属于膜翅目、鞘翅目、双翅目、鳞翅目昆虫,蜂类是有效的传粉者;(3)翅果油树依靠芳香气味、花蜜、花粉和适度紧缩的生殖枝吸引访花昆虫;(4)昆虫的访花活动主要集中在11:00~16:00,访花活动易受气象因素影响;(5)自然条件下,翅果油树平均每日每花被访问的频次为(1.93±1.64)次,人工放蜂可显著增加传粉强度;(6)交配系统属居群内的异花传粉,仍属于广义的自花传粉范畴.传粉昆虫少,传粉效率低是翅果油树致濒的重要因素之一. 相似文献
45.
46.
从牛奶子(Elaeagnus umbellata Thunb.)的叶片、枝条、种子中提取多糖,并研究其抗氧化活性.采用热水提取、Savage法除蛋白、80%乙醇沉淀得其粗多糖.以Vc为对照,用番红花红光度法测定其对羟基自由基的清除作用;用邻苯三酚自氧化法测定其对超氧阴离子的清除作用;用Fe3+还原力法测定其还原能力.结果表明:3个部位所含多糖对羟基自由基、超氧阴离子自由基都可起到有效的清除或抑制作用,其中对羟基自由基清除活性依次为:种子>叶片>枝条>Vc,对超氧阴离子自由基清除活性依次为:种子>Vc>叶片>枝条,3个部位所含多糖都有还原性,但效果都不如硫脲. 相似文献
47.
采用苯酚—硫酸法,测定比较了翅果油树叶片、枝条和种子3个部位的多糖含量;并分别采用邻苯三酚自氧化法和番红花红O—Mn2+—H2O2光度法测定比较了3个部位多糖对超氧离子、羟基自由基的清除活性。结果表明:翅果油树叶片、枝条和种子多糖平均含量依次为69.42,23.15,56.47 mg.g-1;3个部位多糖对羟基自由基、超氧阴离子自由基均有清除作用,其清除超氧离子自由基的活性依次为:Vc>种子>枝条>叶片,清除羟基自由基的活性依次为:叶片>种子>Vc>枝条。该研究结果表明,翅果油树叶片和种子均可作为利用该植物开发天然抗氧化剂的优选部位。 相似文献
48.
以山西翼城翅果油树(Elaeagnus mollis)自然保护区的翅果油树为研究对象,利用LI-3000A叶面积测定仪测量其单叶面积,用Li-6400便携式光合作用测定系统测定单位叶面积饱和光合速率(Aaraa),用H2SO4-H2O2消煮法测定叶氮含量,计算叶性参数比叶面积(SLA)、单位叶重量饱和光合速率(Amass)、光合氮利用率(PNUE)和单位重量叶氮含量(Nmass)的值,并研究它们与径级之间的关系.结果表明:随着翅果油树径级的增加,SLA、Nmass、Aarea、Amass和PNUE值先下降后上升,当翅果油树径级为7.5 cm左右时,SLA、Nmass、Aarea、Amass和PNUE值均降到最小值,表明径级为7.5 cm左右的翅果油树其光合能力最弱、光合氮利用率较低且生存压力较大.翅果油树叶性参数是研究翅果油树种群动态变化的有效指标,可为研究翅果油树种群动态提供更为便捷的方法. 相似文献
49.
A new compound, namely isoamericanol B (1), together with 18 known compounds were isolated from the dry leaves and twigs of Elaeagnus lanceolata. The structure of 1 was determined to be rel-(7′Z)-(7β, 8α) 3 methoxy 4, 9′ dihydroxy 3′, 7 epoxy 8, 4′ oxyneolign 7′ ene on the basis of detailed spectroscopic analysis. 相似文献
50.
濒危植物翅果油树愈伤组织诱导中褐变问题的研究 总被引:11,自引:0,他引:11
针对翅果油树愈伤组织诱导的褐变问题,从外植体、碳源、抗氧剂的类型及浓度等的筛选进行了研究。结果表明;幼龄的茎段是诱导愈伤组织的最佳材料。葡萄糖为碳源的培养基能有效地防止褐变。抗氧化剂Vc和Na2S2O3能减轻褐变程度,其中0.15g/L的Vc效果最佳,其次为0.1g/L和0.2g/L。Na2S2O3对褐变的抑制作用不及Vc,3种浓度无明显区别。吸附剂AC不能防止外植体褐变,且抑制愈伤组织的诱导。 相似文献