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1.
黄土高原蕨类植物区系特点的初步研究   总被引:3,自引:3,他引:0  
对黄土高原的蕨类植物区系组成、分类及其特点进行了研究。结果表明,黄土高原有蕨类植物26科、53属、184种及3变种,种类较多的科有蹄盖蕨科(30种)、鳞毛蕨科(26种)、水龙骨科(20种)、铁角蕨科(12种)、卷柏科(12种)、中国蕨科(11种)及裸子蕨科(10种)等。这7科的种类共计121种,占本地区总种数的64.71%。种类较多的属有鳞毛蕨属(13种)、郑柏属(12种)、耳蕨属(11种)、铁角蕨属(11种)、蹄盖蕨属(10种)、瓦韦属(10种)、铁线蕨属(9种)及岩蕨属(9种)等。这8属的种类共计85种,占本地区总种数45.46%,黄土高原蕨类植物区系属的地理成分可划分为15个分布区类型。热带、亚热带分布类型的有18属,占总属数的41.86%,北温带及寒带分布类型的有22属,占总属数(世界分布属除外)的51.16%,其中,亚洲分布类型的最多,计有16属,占总属数的37.20%,表明黄封同原蕨类植物区系是温带类型,区系地理成分以华北区蕨类植物为主,同时也集中了华中、华东、东北、西北以及西南的蕨类植物。而中国特有的分布属只有1属。  相似文献   

2.
Non-neutral patterns of species abundance in grassland communities   总被引:6,自引:0,他引:6  
Although the distribution of plant species abundance in a Minnesota grassland was consistent with neutral theory, niche but not neutral mechanisms were supported by the ability of species traits to predict species abundances in three experimental grassland communities. In particular, data from 27 species grown in monoculture showed that species differed in a trait, R *, which is the level to which each species reduced the concentration of soil nitrate, the limiting soil nutrient and which is predicted to be inversely associated with competitive ability for nitrogen (N). In these N-limited habitats, species abundance ranks correlated with their predicted competitive ranks: low R * species, on average dominated. These correlations were significantly different than expected for neutral theory, which assumes the exchangeability of species traits. Additionally, we found that changes in relative abundance after environmental change (N-addition or disturbance) were not neutral but also were significantly associated with R *.  相似文献   

3.
Twenty-three species of Conus were described by authors other than Linnaeus between 1766 and 1786. Of these, 3 are Eocene species from England described by Solander in Brander (1766), and the remainder are Recent. Chemnitz (1777) described one valid species. Of the 10 species described by Born (1778), 7 are valid, 2 are junior synonyms of Linnaean species, and 1 is a nomen dubium. Solander in [Lightfoot] (1786) described 5 species, of which 3 are valid and 2 are junior synonyms of Linnaean species. Lightfoot (1786) described 4 species, of which 1 is valid and 3 are junior synonyms of Linnaean species.
Holotypes of 7 species and lectotypes of 3 species exist, and representatives of lecto-types of 10 species have been selected. All of these types are illustrated photographically.
Between 1758 and 1786, 60 species of Conus were described, of which 45 are now considered valid. Of these, 42 are Recent.  相似文献   

4.
该研究以查阅文献和野外实地调查相结合的方法,对锡林郭勒草原国家级自然保护区种子植物进行调查、统计、排序,并对该区系种子植物的种类组成、水分生态类型、生活型及种的地理成分进行分析。结果表明:锡林郭勒草原国家级自然保护区有野生种子植物856种,分别隶属于87科,345属;其中,裸子植物3科,5属,11种;被子植物84科,340属,845种。植物水分生态类型以中生植物为主,共559种,占区系总种数的65.30%;旱生植物213种,占区系总种数的24.88%。生活型以草本植物为主,占区系总种数的88.67%。区系中种的地理成分较为复杂,既反映出保护区植物地域性强的特征,也反映出该区域生境类型多样、植物丰富度高的特征。  相似文献   

5.
依据2010年4月、7月和11月对浙江中部近海上升流海域进行的海洋调查资料,运用定量、定性方法,探讨了上升流对该海域浮游动物生态类群分布的影响.结果表明:3个季节共鉴定浮游动物64种,桡足类占主要优势,包括5个生态类群,分别是暖温带近海种、暖温带外海种、亚热带近海种、亚热带外海种和热带大洋种.在种类数组成上,春季以暖温带近海种为主,夏季则是亚热带近海种和亚热带外海种居多,秋季也是亚热带种居多,其中夏季暖温带种种类数要高于春季和秋季,这一现象与同时期东黄海沿海有所不同,主要是由于上升流将一些在海洋底部度夏的暖温种带至海洋表面造成的.此外,3个季节生态类群都是以近海种为主,表明沿岸流是影响这一海域的最主要的水团.在丰度组成上,4月暖温带近海种占总丰度的98.79%,7月暖温带近海种也是组成丰度的重要部分,10月则是亚热带近海种丰度最高.丰度组成所反映的规律与种类数组成规律一致.上升流的存在导致夏季近海暖温带种大量出现,是影响这一海域浮游动物生态类群组成的重要因素;受长江径流和椒江径流的影响,近海种成为主要生态类群,是这一海域浮游动物的一个重要的生态特征.  相似文献   

6.
Non-nodulation occurs sporadically throughout the family Leguminosae, the genus Acacia is unusual as there are a range of species which are consistently non-nodulating, but which are closely related to species able to form nodules. A comparative study of these and coexisting related nodulating species has been made to establish whether the non-nodulating species exhibited any pre-infection characteristics which are typical of their nodulating counterparts. The non-nodulating species did not form any nodule-like structures, but exhibited pre-infection characteristics such as rhizobial attachment similar to that of their nodulating counterparts. The root exudate of nodulating A. polyacantha contained stimulatory compounds which aided binding of rhizobia to the roots of the non-nodulating species and nodulation was completely inhibited when A. polyacantha was co-cultured with a non-nodulating species.  相似文献   

7.
汉中地区汉水流域水生维管植物种类及地理分布   总被引:2,自引:0,他引:2  
赵桦  王东 《西北植物学报》2002,22(6):1445-1450
经野外调查,采集标本与鉴定分析,汉中地区汉水流域共有水生维管植物69种,包括蕨类植物3种,种子植物66种,分别隶属于32科48属。其中挺水植物41种,浮水及浮叶植物11种,沉水植物17种。66种种子植物分别隶属于46属,有7种地理分布类型,其中以世界分布类型成分居多,共21属,占本地区水生种子植物总属数的45.7%;热带分布类型成分13属,占28.3%,温带分布类型12属,占26.0%。调查分析发现8种6该区域的新分布种,即:竹叶眼子菜,南方眼子菜,小茨藻,大茨藻,水毛花,穗花狐尾藻,有梗石龙尾的狸藻;新记录属4个,即:茨藻属,狐尾藻属,石龙尾属和狸藻属;新记录科2个,即;茨藻科和小二仙草科。  相似文献   

8.
We investigated the conservation concern of Azorean forest fragments and the entire Terceira Island surface using arthropod species vulnerability as defined by the Kattan index, which is based on species rarity. Species rarity was evaluated according to geographical distribution (endemic vs. non endemic species), habitat specialization (distribution across biotopes) and population size (individuals collected in standardized samples). Geographical rarity was considered at 'global' scale (species endemic to the Azorean islands) and 'regional' scale (single island endemics). Measures of species vulnerability were combined into two indices of conservation concern for each forest fragment: (1) the Biodiversity Conservation Concern index, BCC, which reflects the average rarity score of the species present in a site, and (2) one proposed here and termed Biodiversity Conservation Weight, BCW, which reflects the sum of rarity scores of the same species assemblage. BCW was preferable to prioritise the areas with highest number of vulnerable species, whereas BCC helped the identification of areas with few, but highly threatened species due to a combination of different types of rarity.A novel approach is introduced in which BCC and BCW indices were also adapted to deal with probabilities of occurrence instead of presence/absence data. The new probabilistic indices, termed pBCC and pBCW, were applied to Terceira Island for which we modelled species distributions to reconstruct species occurrence with different degree of probability also in areas from which data were not available. The application of the probabilistic indices revealed that some island sectors occupied by secondary vegetation, and hence not included in the current set of protected areas, may in fact host some rare species. This result suggests that protecting marginal non-natural areas which are however reservoirs of vulnerable species may also be important, especially when areas with well preserved primary habitats are scarce.  相似文献   

9.
宁波北仑植物资源及珍稀保护植物研究   总被引:2,自引:0,他引:2  
宁波市北仑区蕴藏着丰富的植物资源,据调查有野生维管植物158科454属712种,在这些植物中,有药用植物276种、用材树种95种、观赏植物87种、纤维植物60种、防护植物55种、薪炭植物52种、油脂植物48种、饲料植物42种、野生水果38种、芳香植物30种、淀粉植物25种、蜜源植物24种、野菜植物18种等,大多具有开发和可持续利用的价值;此外,北仑还有国家野生重点保护植物4科5属5种、古树名木15科17属17种,这些植物对开发建设中的北仑来说,是极其宝贵的自然资源.因此,为使北仑区的植物资源得到可持续的利用,对其开发利用和保护提出了建议.  相似文献   

10.
福建茫荡山黄枝润楠群落生活型特征研究   总被引:1,自引:2,他引:1  
福建茫荡山黄枝润楠群落植物种类丰富,有维管植物69科102属133种。高位芽植物占绝对优势,共计103种,占总种数的77.4%,其中,小高位芽植物居首位,共37种,占总种数的27.8%;藤本植物25种,占总种数的18.8%。该群落植物叶的性质以常绿、小型叶、单叶、草质、非全缘为主,具有典型的中亚热带常绿阔叶林外貌特征。  相似文献   

11.
Summary

A review of the conservation status of fish in the estuarine environment around the South African coastline reveals that some species face serious problems associated either with habitat destruction, and its associated biological, physical and chemical components or exploitation. The 65 species considered fall into three categories; truly estuarine species, which are dependent on estuaries for their entire life; marine species dependent on estuaries during the juvenile phase of their life cycle; and marine species whose juveniles occur mainly in estuaries but are also found at sea. Included in the first two categories are 14 species of fish which are on the South African Red Data list. These comprise one species which is endangered, five which are vulnerable and eight which are rare. All groups are considered in relation to factors in estuaries which are affecting their populations. A conservation strategy is suggested for certain estuarine types or for specific estuaries which could ensure the survival of the entire range of estuarine faunas.  相似文献   

12.
Non-native species can alter patterns of species diversity at multiple spatial scales, but the processes that underlie multi-scale effects remain unclear. Here we show that non-native species reduce native diversity at multiple scales through simultaneous disruption of two processes of native community assembly: species immigration, which enhances alpha diversity, and community divergence, which enhances beta diversity. Community divergence refers to the process in which local communities diverge over time in species composition because the history of species immigration and, consequently, the way species affect one another within communities are variable among communities. Continuous experimental removal of species over four years of floodplain succession revealed that, when non-native species were excluded, stochastic variation in the timing of a dominant native species’ arrival allowed local communities to diverge, thereby enhancing beta diversity, without compromising promotion of alpha diversity by species immigration. In contrast, when non-native species were allowed to enter experimental plots, they not only reduced native alpha diversity by limiting immigration, but also diminished the dominant native species’ role in enhancing native beta diversity. Our results highlight the importance of community assembly and succession for understanding multi-scale effects of non-native species.  相似文献   

13.
在广西南宁市调查台湾乳白蚁Coptotermes formosanus Shiraki对园林绿化树木的危害情况及其筑巢规律。结果表明,在调查的57种树木中,有44种树木受到台湾乳白蚁的侵害,占调查树种的77.19%,树木受害株率13.38%,严重受害株率1.63%。侧柏Thuja arientalis、荫香Cinnamomum burmannii和银桦Grevillea robusta的严重受害率最高,分别为15.85%、13.43%和11.11%。台湾乳白蚁筑巢对树木种类有明显的选择性,可在树心筑巢的树种有16种,隶属于11科14属,其中筑巢率较高的树种为荫香、侧柏、银桦和桂花树Osmanthus fragrans,分别占所调查树木的16.42%、15.85%、11.11%和10.91%;其次为樟树Cinnamonaom camphora、大叶桉Eucalyptus robusta和白千层Melaleuca leucadendta,筑巢率分别为7.98%、5.76%和3.42%。  相似文献   

14.
周仕顺  王洪  朱华   《广西植物》2007,27(3):475-481,502
根据5个20m×25m样地的调查资料,对分布于澜沧江糯扎渡河岸山地,以厚皮树、家麻树为优势种的季雨林群落进行了分析研究,结果显示:(1)该群落乔木层以落叶成分厚皮树和家麻树为优势种,层间以常绿的大型木质藤本云南翅子藤为特征;(2)在群落2500m2样地内,共计维管束植物72种,隶属于38科65属;其中有乔木25种,草本植物25种,灌木10种和层间藤本植物12种;(3)综合5个样地后计算所得群落乔木层树种丰富度为25种,Shannon-Wiener指数为2.9010,Pielou均匀度指数为0.9012,Simpson指数为0.9346,在群落中,随着乔木径级的增大,个体数和种数逐渐减小;(4)该群落主要以高位芽植物为主,并以中高位芽植物为优势,占所统计总种数的35.8%;(5)该群落中落叶种类占总种数的62.5%,中叶占47.2%,小叶占41.7%,单叶占69.4%,纸质叶占61.1%,全缘叶占56.9%;(6)该群落的物种数/样地面积关系曲线显示在取样面积1000m2时开始趋于平缓,意味着该取样面积可以考虑作为群落最小取样面积。  相似文献   

15.
汉中地区三个自然保护区蝗虫种类调查   总被引:2,自引:2,他引:0  
汉中有陕西长青国家级自然保护区、陕西洋县朱自然保护区和陕西省佛坪国家级自然保护区。经过调查,3个自然保护区共有蝗虫39种,隶属5科27属,其中锥头蝗科Pyrgomorphidae仅1属1种,斑腿蝗科Catantopidae8属16种,网翅蝗科Arcyperidae5属9种,斑翅蝗科Oedipodidae9属9种,剑角蝗科Acrididae4属4种。3个自然保护区中,斑腿蝗科物种和属的多样性较为丰富。3个自然保护区的蝗虫区系组成包括东洋区种类17种、古北区7种、两区共有种8种和秦巴山区特有种7种。秦巴山区特有种的相对数量比较多(179%),这反映出汉中自然环境的特殊性。  相似文献   

16.
Lloyd W. Morrison 《Oecologia》1996,107(2):243-256
The ant species inhabiting three remote Polynesian islands were censused by hand collecting techniques. Three commonly occurring species, which exhibited complementary distribution patterns, were numerically and behaviorally dominant to other species in the communities in which they occurred. Field observations and laboratory experiments showed that negative interspecific interactions were important in maintaining the exclusive territories of the dominant species. Habitat also played a role in determining the distribution of dominant species. Pairwise tests of association among all species revealed dominant species were commonly positively associated with their own non-overlapping group of subordinate species, forming a large-scale mosaic distribution pattern of dominant and subordinate species. Baiting experiments, conducted with and without the dominant species removed, demonstrated that the presence of the dominant species decreased: (1) the proportion of baits occupied by other species, and (2) overall ant species diversity, at rich food resources. In ant communities where one of the three recognized dominant species was present, the outcome of negative interspecific interactions among species was more predictable than in communities without a recognized dominant. The same patterns were evident regardless of which of the three dominant species was present in the community. These patterns of community organization observed in this relatively newly assembled fauna are very similar to those reported from studies of older ant communities in mainland areas.  相似文献   

17.
四川九寨沟自然保护区的鸟类资源及区系   总被引:7,自引:0,他引:7  
2002年4月-2003年6月对四川九寨沟自然保护区的鸟类进行调查,并结合历史文献,确认保护区有鸟类222种,以留鸟和夏候鸟为主,占保护区鸟类总数的86.48%。对保护区繁殖鸟类的区系分析表明:古北界种类占繁殖鸟总数的33.85%,东洋界种类占55.21%,广布种占10.94%,可见东洋界种类占优势。保护区内有国家Ⅰ、Ⅱ级保护动物27种,我国特有种17种,占我国特有种的24.6%。列入CITES名录的有20种。对保护区鸟类的垂直区系分析发现,随海拔高度的增加,东洋界成分所占比例增加,主要是喜马拉雅-横断山区型的比例增加,在海拔3000m以上,喜马拉雅.横断山区型占绝对优势,所占比例超过50%;其它东洋界成分,随海拔高度的增加所占比例减少。  相似文献   

18.
镜泊湖自然保护区种子植物区系的研究   总被引:4,自引:1,他引:3  
经野外调查及资料统计,已知镜泊湖自然保护区有野生种子植物101科395属809种,其中裸子植物3科7属12种,被子植物98科388属797种。本区地理成分复杂。以温带成分占绝对优势。温带分布属287属。占总属数的85.42%;温带分布种647种。占总种数82.40%,其中国-日本分布和东北分布有292种。占总种数的37.2%。是本区温带地理成分的核心。  相似文献   

19.
Some plant species from which viruses are difficult to transmit to other species by sap inoculation contain substances that inhibit infection. The extent to which infection is inhibited by these substances depends on the species of plants to which inoculations are made and not on the identity of the virus. The inhibitors are largely ineffective in preventing infection of the species which contain them.
Infection of cucumber was less affected than any of the other species by all the inhibitors tested.  相似文献   

20.
生物多样性的编目和分类以及生物多样性监测是全球生物多样性研究的两个核心内容。物种编目是了解物种多样性的基础, 只有掌握物种分布格局及物种与环境的关系, 才能为物种监测和科学管理提供依据。作为浙江种子植物研究的“家底”, 本文在《浙江植物志(新编)》编研的基础上, 系统整理了浙江种子植物的物种名录。结果显示, 浙江共有种子植物212科1,469属4,430种, 其中野生植物有190科1,085属3,347种。所含种数多于100种的科有禾本科(285种)、莎草科(216种)、菊科(186种)、蔷薇科(153种)、兰科(126种)、蝶形花科(109种)和唇形科(108种); 含20种以上的属有15属, 包括薹草属(Carex, 126种)、刚竹属(Phyllostachys, 44种)、悬钩子属(Rubus, 44种)、冬青属(Ilex, 35种)、蓼属(Polygonum, 34种)、珍珠菜属(Lysimachia, 32种)、铁线莲属(Clematis, 31种)、景天属(Sedum, 28种)、槭属(Acer, 26种)、荚蒾属(Viburnum, 26种)、飘拂草属(Fimbristylis, 26种)、蒿属(Artemisia, 25种)、堇菜属(Viola, 22种)、葡萄属(Vitis, 21种)和山矾属(Symplocos, 21种)。其区系特点主要反映在: 物种丰富, 其科属组成多样; 保存了较多古老孑遗植物; 地理成分多样, 联系广泛, 由热带向温带过渡; 中国特有科2科、中国特有属45属、浙江(准)特有种近500种(含亚种和变种), 珍稀濒危植物丰富, 96种为国家重点保护植物; 外来植物多, 入侵风险大, 有些种已形成明显的危害。  相似文献   

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