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1.
Alpha and beta diversity and habitat niche relationships of a poor, boreal mire was studied, based upon an ordination by detrended correspondence analysis and a subjective classification. The three first DCA axes were interpreted as variation along the following ecoclines: (1) mire expanse carpet–mire expanse hummock–mire margin hummock, (2) nutrient status: ombrotrophic–poor minerotrophic, and as a coenocline (3) associated with peat-producing ability of the vegetation with an unclear ecological basis. The autecology of the 39 most frequent species was decribed with respect to these gradients. Alpha diversity patterns varied considerably between coenoclines. Beta diversity was always higher in the bottom layer than in the field layer. Habitat niche breadth was strongly correlated with species abundance, and separable into a frequency-independent and a frequency-dependent component. The former decreased from vascular plants to hepatics, and further to Sphagnum spp. It was argued that the importance of interactions was high in the bottom layer, particularly among Sphagnum spp., but also among hepatics. Interactions among vascular plants was considered unimportant, except in hummocks. Plant strategies were discussed. The niche breadth approach was evaluated, and found fruitful, while niche overlap was considered to provide redundant information. The importance of each of (1) interspecific interactions, (2) destabilizing factors, (3) stress, and (4) chance, as structuring factors in boreal mires, is discussed. Boreal mires are considered to conform to the patch-dynamics theory of non-equilibrium coexistence.  相似文献   

2.
邱杨  张金屯 《生态学报》2000,20(2):199-206
首次在DCCA排序的基础上使用排序轴分类法(OAC),将其发展为一个新的典范分类方法,并应用这种方法对山西关帝山八水沟的植物群落进行了数量分类,共划分出5类,效果较好。方差分析与多重比较表明,环境与群落结构因子在不同群落之间存在较为显著的差异,表明DCCA排序轴分类法能较好地反映群落与环境的变异。因为DCCA排序轴分类同时结合了植被因子与环境因子,所以它能较好地表达植物群落的环境梯度和结构梯度,反  相似文献   

3.
4.
Hydro-ecological analysis of the Biebrza mire (Poland)   总被引:2,自引:0,他引:2  
Vegetation composition and structure of 58 sites along gradients in the valley mire of Biebrza, Poland, are related to physical and chemical variables of groundwater and peat. The three most prominent hydrochemical processes in the valley are (a) dissolution of calcite; (b) dissolution of iron, manganese and aluminium; and (c) enrichment with nitrogen and potassium. Major factors determining these processes are vertical flow of the groundwater and river flooding.Within the rheophilous zone of the mire, calcium-richness of the shallow groundwater and base-saturation of the peat are caused by upward seepage of groundwater originating from adjacent higher grounds. This groundwater movement keeps the larger part of the mire saturated with calcium.Good correlations exist between hydrochemistry and vegetation patterns. Groundwater-fed sites support a characteristic rich fen vegetation (Caricetum limoso-diandrae) with a low biomass production. The flood-plain vegetation consists of highly-productive communities of Glycerietum maximae and Caricetum elatae. In a belt in the Upper Basin where neither flooding nor upward seepage occurs, succession, probably caused by intensified drainage, leads to a dwarf-shrub vegetation (Betuletum humilis; poor fen).  相似文献   

5.
Results are reported for a potentiometric and spectroscopic (visible, CD, and EPR) study of the complexes of fibrinopeptide A (Ala-Asp-Ser-Gly-Glu-Gly-Asp-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg) with H+, Cu2+ and Zn2+. They show that the peptide forms stable complexes with Cu2+, largely as a result of the Asp2 residue, and that its coordination behavior is almost identical to that of the N-terminal tetrapeptide fragment, Ala-Asp-Ser-Gly. Hence the influence of the remaining amino acid residues on coordination to Cu2+ is insignificant.  相似文献   

6.
The hemocyanins of the horseshoe crab Limulus polyphemus (48-mer), the tarantula Eurypelma californicum (24-mer), and the lycosid spider Cupiennius salei (dodecamer, hexamer) were dissociated into subunits, the subunits isolated and studied by two-dimensional immunoelectrophoresis for interspecific cross-reactivities. Among the subunits a to g of Eurypelma on the one side, and I to VI of Limulus on the other, a number of cross-reactions were obtained which agree with the topologic subunit positions in the published models of quaternary structure: a = II, b-c = V-VI, d = IV, e = I, f = IIIb, g = IIIa (IIa). However, cross-reactivity was only strong in the following combinations: a/II, d/IV, b-c/V-VI (the monomers of the two heterodimers could not be correlated individually). A rather weak cross-reaction was obtained in the case of e/I and g/IIIa (IIa); a cross-reaction between f and IIIb was almost undetectable. On the other hand, f/IV clearly cross-reacted, and so did e/IIIa (IIa), which apparently is not in agreement with the two models of quaternary structure. These unexpected relationships, however, indicate the possible phylogeny of the subunits. Antiserum against Cupiennius hemocyanin precipitated subunit f of Eurypelma and subunit IV of Limulus and, moreover, revealed common antigen determinants present on these subunits. Denaturation of hemocyanin subunits of the three species with 8M urea yielded a completely different immunological behavior in that in all intra- and interspecific combinations the reaction of immunological identity was obtained. The published models of quaternary structure and a possible subunit phylogeny of cheliceratan hemocyanins is discussed in view of the present results and the results of the preceding paper. [Markl, J. et al. (1984) Hoppe-Seyler's Z. Physiol. Chem. 365, 619-631.]  相似文献   

7.
8.
The paper deals with three plant communities of forest clearings and forest paths in the neighbourhood of Aas, not studied hitherto in Norway, i.e.Carici leporinae-Agrostietum tenuis, Chamaenerion angustifolium-Calamagrostis purpurea comm. andRubo-Pteridietum aquilini.  相似文献   

9.
A stratigraphically oriented series of the Miocene foraminiferal speciesBrizalina mandoroveensis from Ikang, Cameroon, was analyzed both by conventional multivariate morphometric procedures and by the tensor biometric method of Bookstein (1986;Statist. Sci. 1, 181–142), a method which analyzes sets of landmark points rather than specific variables of shape or size. The conventional analysis used five size-measures upon 170 specimens from five stratigraphic levels; the tensor analysis encompassed six landmarks (12 coordinates) upon 50 specimens. Whereas certain features appeared in both analyses, such as the separation between levels one and five, the techniques did not always agree with respect to the interpretation of those findings or about most details in the sequence of mean phenotypes. The canonical variate analysis bases its ordination upon a general size factor (the meaning of which is obscured by the foreshortening of within-group variation which is built into the technique). The tensor analysis locates a similar ordination using mainly features of shape.  相似文献   

10.
Morphological and cultural studies of Polyporus maculatissimus and P. portentosus are presented. Neolentiporus gen. nov. is proposed to accommodate P. maculatissimus , a species with a striking macromorphological similarity with the north temperate P. squamosus . The new genus is characterized by medium to large stipitate fruitbodies with a poroid hymenophore, circular to flabellate pilei with a scaly surface and an excentric or lateral stipe that sometimes is reduced to a short, robust umbo. The hyphal system is dimitic with clamped, irregularly thick-walled generative hyphae that do not react with cresyl-blue, and terminal, unbranched, thick-walled skeletal hyphae that are strongly metachromatic in cresyl-blue. Spores are cylindric, hyaline, thin-walled, inamyloid and binucleate. The sexuality is bipolar, the nuclear behavior is astatocoeno-cytic and the associated wood-rot is brown. The new genus is regarded as the poroid counterpart of the agaricoid Neolentinus. Polyporus portenrosus is included in Laetiporus on the basis of its yellowish fruitbodies, its soft, punky context, its hyphal system composed of simple septate generative hyphae and binding hyphae, its holocoenocytic nuclear behavior and its associated brown wood-rot. A new code symbol, i.e. '9s' is proposed to codify the presence, in cultures, of simple-septate generative hyphae with irregularly thickened walls.  相似文献   

11.
Identification of gadoid species (Pisces, Gadidae) by PCR-RFLP analysis   总被引:3,自引:0,他引:3  
A rapid PCR-RFLP analysis was optimized to identify the presence of 3 closely related gadoid fish species: Alaska pollack Theragra chalcogramma, Pacific cod Gadus macrocephalus and Atlantic cod Gadus morhua in commercial seafood products. Gadoid universal primers were designed for PCR amplification of a 558-bp fragment encoding the mitochondrial cytochrome b gene. Without purification of the PCR products, double digestion with Eco32I and Eco105I restriction enzymes generated reproducible species-specific restriction patterns visualizing 3 fragments (106 bp, 161 bp and 291 bp) in Alaska pollack and 2 fragments (106 bp and 452 bp) in Pacific cod, whereas no cleavage was observed in Atlantic cod. This PCR-RFLP analysis is simple, rapid and reliable, and therefore can be routinely applied to discover fraudulent substitution among 3 economically important gadoid species in commercial seafood products.  相似文献   

12.
From the Upper Jurassic flora of Andöya, Northern Norway, which is now under revision, Pseudotorellia heeri sp. nov. is described on cuticular characters. It has been shown that some specimens previously described by Heer as Baiera pulchella and Phoenicopsis latior from the same locality belong to the new species.  相似文献   

13.
The true Michaelis constant for GSH and CDNB was 0.287 mM and 0.180 mM, respectively. Regarding the quantitative effect of Cu(II) and Cd(II) inhibition on the GST system, the I50 value for Cu(II) was 0.250 mM; in contrast, Cd(II) GST-inhibition did not reach the I50 value. When the varied substrate was GSH and CDNB was fixed at saturant concentration, the Cu(II)-inhibition was consistent with a pure competitive pattern. However a mixed pattern was found when CDNB was the varied substrate and GSSH was fixed at saturant concentration. The Cd(II) inhibition effect was consistent with an uncompetitive pattern when GSH was the varied substrate and CDNB was kept at saturant level. When CDNB changed over an extensive range of concentration, the inhibition effect shows a mixed inhibition pattern with a competitive character. In addition the inhibition constants of Cu(II) were one order of magnitude lower than those of Cd(II).  相似文献   

14.
T. Edland 《BioControl》1965,10(4):331-333
Résumé La NoctuelleEupsilia transversa Hufn. était abondante dans l'Ouest de la Norvège en 1962, la chenille causant de graves dégats aux arbres fruitiers. En 1963, une infestation de granulose apparut sur les chenilles et en deux années réduisit la population à un niveau très bas. Le syndrome de la larve malade est décrit. Les résultats de quelques essais d'infection à petite échelle permettent de considérer ce virus comme capable de réduire effectivement la population deE. transversa dans les conditions de laboratoire. La granulose semble être léthale à tous les stades du ravageur sauf le dernier.   相似文献   

15.
16.
Mitotic waves during superficial cleavage and early gastrulation were analyzed quantitatively in Calliphora. Three consecutive patterns are present: (1) a monotonic anterioposterior mitotic gradient during early superficial cleavage; (2) a double mitotic gradient from the anterior and posterior poles during superficial cleavage, especially toward the end of the period; and (3) more complicated patterns with intermediate mitotic centers during the last superficial cleavage division and during early gastrulation. Mitotic gradients are absent in many eggs during early superficial cleavage, but they then become ubiquitous. The gradients are longitudinal; no transverse component was detected before gastrulation. Anterior and posterior gradient patterns are not mirror images of each other; mitotic activity always starts earlier anteriorly. The gradients are accompanied by a pronounced increase in interphase length. The mitotic gradients are compared with the morphogenetic gradients predicted in a current model for pattern specification in insect eggs.  相似文献   

17.
The Raman spectra of crystalline bis(pyrophosphato)tetrazinc(II) and -manganese(II) decahydrates, M4(P2O7)2 · 10H2O (M = Zn and Mn), have been investigated at room temperature. The Mn(II) salt readily underwent photodecomposition upon extended exposure to 785-nm laser irradiation and so could not be examined under high pressures in a diamond-anvil cell. The Zn(II) salt was much more stable and was studied successfully at pressures up to ∼35 kbar. The pressure dependences of the δsPO2, νsPOP, νasPOP, νsPO2, and νasPO2 internal modes of the pyrophosphate group and of an external H2O mode indicated the occurrence of a pressure-induced phase transition in the 15-20 kbar region. Further confirmation of this structural change came from the appearance of four initially forbidden modes in the 19-26 kbar range. This phase transition proved to be reversible upon release of the applied pressure. The pressure dependences before and after the phase transition were −0.22 to 0.66 and 0.06 to 0.33 cm−1/kbar, respectively.  相似文献   

18.
The Alkor-Deep (140 m), which forms part of a depression system in the northern Kattegat channel east of the island of Læsø (Denmark), is the location of a self sustaining population of Northern krill, Meganyctiphanes norvegica (Euphausiacea). This population is exposed to one of the most pronounced thermal gradients within the distributional range of this pelagic crustacean. During summer, the temperature of the water column ranges between 4 and 6 in the deep to 16 °C near the surface which results in the krill being exposed to temperature differences of 8–10 °C during diel vertical migration. Oxygen consumption rates were used to investigate the physiological adaptation of the animal to such gradients in temperature. The rates were found to increase exponentially from 31 mol O2 h-1 gdw -1 at 4 °C to 72 mol O2 h-1 gdw -1 at 16 °C, giving a Q 10-value of 2.0, and indicating that physiological adaptation to varying thermal conditions does not take place. Behavioural adaptations are discussed which may help the krill to cope with large temperature gradients in their environment.  相似文献   

19.
滇东南黄连山秋海棠属一新种   总被引:1,自引:0,他引:1  
树生秋海棠 新种  (秋海棠组 )图 1Begoniaarboreta Y .M .Shui,sp .nov .[Sect.Diploclium (Wight)A .DC .]Fig .1HabituB garretiiCraib .similis ,sedplantaacaulis ,folio 1basali,capsulisobovoideis ,alisobovatisdiffert.Herbaperennis,decidua ,basituberifera ,tuberibussubglobosis,1cmdiam .Stipulae…  相似文献   

20.
云南东南部秋海棠属侧膜组一新种   总被引:2,自引:0,他引:2  
吴氏秋海棠 新种 (侧膜组 ) 图 1BegoniazhengyianaY .M .Shui,sp .nov .(sect.ColoecentrumIrmsch .) ,Fig .1SpeciessimilisB .luzhaiensiKu ,quaefoliorumlaminisi  相似文献   

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