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1.
Dynamics of vegetation was studied on Stora Alvaret in Öland, Sweden, in comparison with precipitation in the May–July part of the growing period. Three data sets representing three main life forms (shrub, dwarf-shrub, and herbs) were collected. species composition eight grassland permanent plots (1969–1993, ass.Veronica spicata-Avenula pratensis), survival and health status ofJuniperus communis (1975–1993), andCalluna vulgaris cover at two permanent plots for the same period. Mortality ofJuniperus andCalluna and proportion of annual species were synchronized and correlated with severe droughts. *** DIRECT SUPPORT *** A02DO006 00003  相似文献   

2.
Composition and distribution of intertidal ecosystem of rocky and unconsolidated facies were quantitatively studied from 1951 to 1975 in about 40 regions of the White, Barents, Bering, Okchotsk and Japan Seas. According to the degree of similarity (or to the degree of relationship), the investigated intertidal communities can be divided into the following 4 groups: (1) Uniform communities with identical forms as dominant species. A series of uniform communities constitutes a single association. (2) Parallel or vicarious communities with closely related vicarious forms as dominant species. A series of parallel communities constitutes a single formation. (3) Convergent or isomorphic communities with dominant species of the same, although not closely related life forms. A series of convergent communities constitutes a single formation type, or biome. (4) Anisomorphic, yet functionally analogous communities. Parallel communities ofFucus disticbus (northern Atlantic Ocean) andF. evanescens (northern Pacific Ocean), and uniform communities ofF. evanescens from various biogeographic provinces (southern Kuriles and eastern Kamchatka) are used for demonstrating the structure of intertidal biocenoses. In parallel communities, vicarious species are shown to dominate in number of species and, especially, in biomass. In uniform communities, common species are found to be leading forms.  相似文献   

3.
Isolations were made of mould species actively growing on a variety of feeding stuffs stored at fixed humidities between too and 65% for periods of up to 4 years. The factors influencing the species of moulds isolated were: (1) die relative humidity of the atmosphere; (2) the length of the storage period before the isolations were made; (3) the type and origin of die feeding stuffs from which the isolates were obtained.
A critical humidify existed for each species below which the development of mould spores could not take place. At relative humidities (R.H.) between 100 and 90% a large variety of moulds were able to develop. Members of die Mucorales and the Fungi Imperfecti were not isolated below 90% R.H. and, although ***Pemicillium app. flourished between 100 and 85% R.H., they were not isolated below 75% R.H. ***Aspergilhes app., on the other hand, were able to develop under conditions of very restricted moisture supply. Some members of the A. ***glaucus group were able to grow at humidities as low as 65-70%.
In general, the moat commonly occurring moulds on the feeding stuffs used in these trials were small ***ascospored species of the A. ***glaucus group, particularly A. ***repens and A. ruber. It is considered that it is these species that will most frequently cause mould damage to feeding stuffs in commercial stores.  相似文献   

4.
The species composition of four alpine communities in the north-western Caucasus was subjected to a morphological analysis. The communities are an alpine lichen heath type (ALH), aFestuca varia grassland type (FVG), aGeranium-Hedysarum meadow type (GHM) and a snowbed community (SBC). Eighty-two species were studied, using the following morphological parameters: vegetative mobility, presence of rosettes, architectural model, life form according toRaunkiaer and life form according toSerebryakov. Representation spectra were calculated on the basis of species presence, above-ground phytomass proportion and species frequency. The results show that most alpine species have a low vegetative mobility; a semi-rosette growth form; a sympodial semi-rosette model of shoot formation and that they are characterised by the prevalence of hemicryptophytes. Differences between the four communities were found in the following features: tap-rooted and short-rhizome plants dominate in ALH and, moreover, dense-tussock plants are dominant in the phytomass; short-rhizome (species presence) and dense- tussock plants (phytomass) are dominant in FVG; short-rhizome and loose-tussock plants dominant in GHM; semi-shrub (phytomass basis) and loose-tussock plants are dominant of SBC. Tuberiferous, bulbiferous and monocarpic plants are not important in any of the communities. *** DIRECT SUPPORT *** A02DO006 00008  相似文献   

5.
海南兰科植物研究杂记(Ⅰ)   总被引:1,自引:0,他引:1  
报道了海南野生兰科植物新记录属1个,即坚唇兰属(Stereochilus Lindley);新记录种7个,即短轴坚唇兰(Stereochilus brevirachis Christenson)、齿瓣石豆兰(Bulboph yllum levinei Schlechter)、香港带唇兰(Tainia hongkongensis Rolfe)、黄花线柱兰(Zeuxine flava(Wallich ex Lindley) Trimen)、歌绿斑叶兰(Good yera seikoomontana Yamamoto)、长轴白点兰(Thrixspermum saruwatarii (Hayata) Schlechter)和南华竹茎兰(Tropidia nanhuae W.M.Lin,Kuo Huang et T.P.Lin).其中,长轴白点兰和南华竹茎兰均仅记载在台湾有自然分布.  相似文献   

6.
New material of early growth stages of the Silurian (Llandovery) trilobite Acernaspis is described. Pre-adult ontogenetic stages of this genus closely resemble adults of the post-Llandovery genus ***Ananaspis. A heterochronic descent of Ananaspis from Acernaspis is proposed. ***Ananaspis is interpreted as pae-domorphic, having arisen largely through neoteny. Neotenic changes already appear in the lineage in the last Acernaspis species, and Ananaspis then underwent continuous ncotcnic change throughout its known Silurian history. ▭ Heterochrony, neoteny, Silurian, Trilobita, Phacopidae, Acernaspis. Ananaspis.  相似文献   

7.
兰科( Orchidaceae)植物是一类特殊且具有较高研究价值的植物类群[1],物种数量多、生活型多样且进化水平高,中国分布有兰科植物194属1388余种[2]1,是单子叶植物中种类数量最多的一个科;同时,野生兰又是受威胁最为严重的类群之一,全部种类都被列入《野生动植物濒危物种国际贸易公约》,约占该公约涵盖的保护植物数量的90%以上,是名副其实的保护植物中的“旗舰”类群[3]。  相似文献   

8.
广西兰科植物新记录   总被引:1,自引:0,他引:1  
该文报道了广西兰科植物6个新记录物种,即日本对叶兰[Neottia japonica(Blume)Szlachetko]、吉氏羊耳蒜(Liparis tsii H.Z.TianA.Q.Hu)、小羊耳蒜(L.fargesii Finet)、条裂鸢尾兰(Oberonia jenkinsiana Lindley)、果香兰(Cymbidium suavissimum C.Curtis)和大花斑叶兰[Goodyera biflora(Lindley)J.D.Hooker],分别描述了每个物种的分类学特征,提供了相关的引证标本及地理分布信息,并附有彩色照片以供识别。  相似文献   

9.
Two naturally coexisting grassland species—Centaurea jacea (often predominating) andFragaria vesca (subordinate) were grown together in a pot experiment of factorial design, where competition and arbuscular mycorrhiza (AM) inoculation were used as treatments. The effects of competition were one-sided, i.e. the mass ofF. vesca decreased relatively more than that ofC. jacea as a result of competition. The root and total mass ofC. jacea increased with AM inoculation whileF. vesca did not respond. The mass difference betweenC. jacea andF. vesca in a particular pot increased when plants were mycorrhizal, mostly due to the mass increase ofC. jaceae. This can be explained by the differential response of these species to AM. We did not find any indirect indication of the interplant transfer of resources. The results of this experiment show the more unbalanced competition (larger differences in biomass) resulting from AM infection of plants. *** DIRECT SUPPORT *** A02DO006 00010  相似文献   

10.
It has been suggested that variation in the proportion of species in guilds (=guild proportionality) indicates community structuring by guilds in biotic communities. This hypothesis was tested on a subthermophilous grassland and a mesotrophic meadow at a scale of 0.09 m2 based on a five-year data set. Further, variation in the total number of species, variation in the number of species belonging to a guild and non-randomness in species composition of guilds were studied. A number of criteria for guild definition were used, such as life form, Grime's C-S-R strategy, phenology, plant height, pollination and dispersal syndromes, leaf shape and anatomy and taxonomy at the family level. The observed variation in the number of guild species corresponded to the null model in which species assemblages with fixed species richness per square were randomly generated from the species pool. The observed variation in the number of guild species was often higher than the variation calculated for randomly distributed species whereas the variation in the proportion of guild species was in some cases lower than the variation calculated for randomly distributed species with fixed frequencies. Possible reasons for the discrepancy in the results based on different models are discussed. It is concluded that there is little evidence of guilds in the organization of grasslands. *** DIRECT SUPPORT *** A02DO006 00012  相似文献   

11.
报道江西兰科植物分布新记录2种——北插天天麻Gastrodia peichatieniana S. S. Ying和单葶草石斛Dendrobium porphyrochilum Lindley。凭证标本保存于九连山自然保护区植物标本室。  相似文献   

12.
Year-to-year variability of species composition and hay yield were investigated during a six-year period (1988–1993) in a traditionally mown meadow of great species richness at Negrentino in southern Switzerland Climatic parameters (temperature duration of sunshine, global radiation, precipitation, evaporation, relative moisture) measured at a nearby weather station were calculated for ten-day units and compared to quantitative vegetation data. Yields of the first and second harvest were positively correlated with the mean relative moisture during the first and second growth period. Distinct variation patterns were recognized among the 48 species and interpreted as direct or indirect responses of interacting species to climatic conditions during three periods of the year. The first variation pattern including abundant graminoids reflects a strong direct effect by weather conditions in the first growth period. Species of the other variation patterns responsed differently to extreme summer droughts with apparent time-lags. Some species reflect warm and humid conditions in early spring followed by dry conditions in a particular year; others combine features of different variation patterns. *** DIRECT SUPPORT *** A02DO006 00002  相似文献   

13.
References are made to five species of Pinaeeous cones from the Cretaceous. The general morphology of the first three was described by Fliche in 1896. Detailed studies on their anatomy have now enabled revisions to be made in their taxonomy. Pinus argonnensis Fliche has been shown to be indistinguishable from Pityoslrobus soigniesiensis Alvin, described in 1960. Tsugiles rnagnus Fliche and Pinus praemonticola Fliche are specimens of a previously named species, Pityostrobus andraei (Coemans) Seward, and their names have been included in its synonymy. A note on Pityostrobus leckenbyi (Lindley and Hutton) Seward attempts to clarify a few points on its anatomy and taxonomy. Finally the discovery of an additional specimen of Pityoslrobus jacksonii Creber is recorded and some details of this specimen are given.  相似文献   

14.
Summary The author reviews the European species of the Pteromalid genusCallitula Spinola and keys them out. All four species develop as parasites, probably all on small Diptera: two species [pyrrhogaster (Walk.) andbicolor spin.] on Cecidomyids and Chloropids in grass stems, two species are associated withPhragmites communis [C. ferrierei sp. n. andelongatus (Thoms)]. From the latter two one is described as new and in the other (elongatus) the so-far-unknown male is described. *** DIRECT SUPPORT *** A5180147 00002   相似文献   

15.
The density of five major groups of fouling organisms (bacteria, diatoms, choanoflagellates, ciliates, macroorganisms) on seven artificial substrata with surface tensions between 19.0 and 64.5 mN m−1 was studied in the Gulf of Thailand. Two series of test panels of the different substrata were immersed into the sea between 3 hours and 64 days (macrofauna 128 days). The results show that surface tension has a limited impact on the density of the organisms. Only bacteria settled continuously in significantly lower numbers on materials within the minimum bioadhesive range (20–25 mN m−1) than on other substrata. Significant differences between the substrata may disappear after long exposure, as in series 2 after 16 days. For diatoms and protozoa, a colonisation pattern similar to that of bacteria with a minimum of 20–25 mN m−1 was detected after several exposure intervals. However, it was never recorded in more than 3 exposure intervals in a row. The colonisation pattern of macroorganisms could not be attributed to substratum surface tension. An index, called “colonisation degree” is introduced to give a general impression of the density of organisms on the materials tested. The colonisation degree did not show any significant difference at any exposure interval. The present results clearly suggest that substratum surface tension is easily overshadowed by other factors in colonisation processes under natural conditions. *** DIRECT SUPPORT *** A03B6037 00003  相似文献   

16.
Changes in plant community structure after changes in some aspect of the environment such as nutrients or grazing is often ascribed to changes in competitive relationships among the plants. However, very rarely is competition measured directly in such experiments. To distinguish between the direct effects of environmental treatments and changes in competitive relationships, it is necessary to quantify the influence of competition on community structure and compare the magnitude and direction of this influence between environments. We describe an experimental approach to accomplish this that is based on the classic yield-density experiment of agronomy. The approach is called the community-density experiment and requires experimental establishment of a gradient in total initial community density such that absolute densities of each species increase but initial relative abundances of each species stay constant along the gradient. We define various indices of the magnitude of community-level consequences of increasing density that can be compared among environments such as different fertilizer or grazing treatments. We also discuss various practical ways of achieving the experimental density gradient that are suitable for different kinds of communities. *** DIRECT SUPPORT *** A02DO006 00011  相似文献   

17.
The natural hybridization betweenPapio anubis andP. hamadryas in central Ethiopia was studied from a population genetical perspective. Studies were made using electrophoretical blood protein variations as markers in order to clarify the genetic relationship between them. A total of 563 samples from ten populations which were collected in the field studies with a socioecologist in 1976 and 1979 were examined for 34 blood protein loci. Ten of the 34 loci showed polymorphism. The Tf, PA-2 and Es were found to be effective for discriminating between the anubis and hamadryas. Genetic variability, hybridization rate, genetic distance, migration rates and correlations between genetical and morphological and between genetical and behavioral indices were computed and analyzed. The results of the present genetic survey revealed that most of the populations from which the author collected blood samples were more or less hybridized. The Nei's (1975) genetic distance between the two species was estimated to be 0.0679 at most. As this value is too small to consider these species as real biological species, it is supposed that the natural hybrid zone is fairly wide and still expanding now. This work was supported in part by Grants in aid for scientific research (Overseas scientific research, 1975) and of the Overseas Special Research Programme of the Primate Research Institute, Kyoto University in 1978 by Ministry of Education, Science and Culture.  相似文献   

18.
Permanent plots with a fine scale recording system were used to trace the spatiotemporal process within two mountain grasslands in the Krkono?e Mts., Czech Republic. The analysis used autocorrelation over increasing lags in space and/or time. Moran'sI was used to measure the autocorrelation. There was a lot of variation between species both in spatial and temporal correlograms. The spatiotemporal pattern of species correlated well with the growth form of the species and the degree of its clonality. Clonally-growing species tended to have high clumping at distances of a few cells, whereas rosette species often did not show any clumping. The type of clonal growth (compact vs. long spacers) is well corrlated, with the temporal correlogram (species mobility). There is a relation between low mobility and high clumping at low distances. Attempts to explain the mechanisms of species coexistence in these grasslands should take into account the particular structure of the fine-scale dynamics of these communities of predominantly clonal plants. *** DIRECT SUPPORT *** A02DO006 00007  相似文献   

19.
南海东沙岛及太平岛鱼类种类组成和动物地理学特点   总被引:1,自引:0,他引:1  
就笔者等在南海之东沙岛及太平岛两处海域所调查记录到的珊瑚礁鱼类,连同自1975年以来之文献与数据库的记录作综合整理.结果表明,东沙岛有73科652种,太平岛有56科466种,两岛合计共有76科759种.太平岛所记录的总鱼种数较东沙岛为少,主要原因纯系因太平岛之礁域面积较小,且调查次数甚少之故.根据各鱼种地理分布范围之分析,发现在此二岛所记录到的鱼种几乎全部都是印度-太平洋、印度-西太平洋及西太平洋等广泛分布的鱼种,目前只有黄头刻齿雀鲷(Chrysiptera chrysocephala)1种是只在南海发现之鱼种.由此可推测南海的鱼类相应与周边海域或珊瑚三角的鱼类相充分交流,并未有明显隔离或种化的现象.东沙岛及太平岛鱼类相之Sφrensen相似性系数值虽已达85.69%,但其中仍有240种是只分布在东沙岛及台湾(165种),或太平岛及台湾(75种),而未在另一岛屿发现之鱼种,且其中只在太平岛及东沙岛发现的21种及20种鱼中,大多为稀有种,非常不容易被调查到.故推测目前在此二岛所作的调查频度相当不足,如果调查能更密集更长期,则两岛的鱼相会更相似.  相似文献   

20.
Tintinnids are a large group of planktonic ciliates with diverse morphologies. The range of variability in lorica shapes and sizes can be very high even within a single species depending on life stages and environmental conditions, which makes the delimitation of different species based on morphological criteria alone very difficult. Accordingly, comparisons of morphological and molecular variability in tintinnids are necessary to provide a pragmatic approach for establishing species boundaries within this diverse and poorly understood group. We investigated the temporal distribution of species of the hyaline tintinnid Helicostomella (Ciliophora, Tintinnina), which were collected daily from September 2008 to August 2009 in Jangmok Bay of Geoje Island on the south coast of Korea. Two forms - a long form and a short form, were discovered. The long form was found in cold waters in February and March whereas the short form occurred in warm waters from June to October. Thus, these two forms were seasonally isolated. However, all the morphological characteristics for these two forms overlap to some degree. A comparison of the small subunit (SSU) rDNA, ITS1-5.8S-ITS2, and ITS2 sequences from two forms revealed 0.5%, 3.8%, and 5.6% divergences, respectively. Morever, one compensatory base change (CBC) and three hemi-CBCs were identified from ITS2 secondary structures of these two forms. All these data suggest that these two forms represent two distinct species despite their highly similar lorica morphology. The phylogenetic position of the genus Helicostomella was also examined using SSU rDNA sequences.  相似文献   

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