Aboveground plant production and nutrient content of the vegetation in six peatlands in Alberta,Canada

We examined the effects of water level, surface water chemistry, and climatic parameters on aboveground primary plant production, and the tissue nutrient concentrations in the dominant herb species in a bog, three fens, and two marshes. In the fens, total NPP correlated best with NO₃^- and total phosphorus surface water concentrations in 1993 and 1994. Total NPP in the marshes correlated best with alkalinity in 1993, and with soluble reactive phosphorus in 1994. Climatic parameters, such as mean annual growing season temperature, growing degree days, and precipitation, had the most notable effect on moss growth, whereas shrub and herb production correlated significantly with the water level relative to the moss surface. Herb production correlated positively and shrub production correlated negatively with the water level relative to the moss surface. Tissue nutrient concentrations of carbon (C), nitrogen (N), and total phosphorus (TP), and the C:N quotient in Carex lasiocarpa exhibited similar trends in the fens and the marshes. Carbon tissue concentrations in C. lasiocarpa remained unchanged, whereas N and TP tissue levels decreased throughout the growing season. In the site with the highest NPP and presumably the highest stand density, C. lasiocarpa exhibited the highest tissue N and TP levels. Furthermore, TP tissue concentrations in C. lasiocarpa were substantially higher in the marshes than in the fens. Tissue nutrient concentrations in Eriophorum vaginatum in the bog showed variable response patterns. N tissue levels increased, whereas tissue TP concentrations decreased from late June to late August. In the bog, E. vaginatum exhibited similar tissue TP levels to C. lasiocarpa in the fens; however, they were both substantially lower than those found in C. lasiocarpa from the marshes.     

Vegetation along hydrologic, edaphic, and geochemical gradients in a high-elevation poor fen in Canaan Valley, West Virginia

Wetland plant community composition and pattern are regulated by a host of abiotic/environmental gradients and biotic factors. We used multivariate analyses to classify wetland plant communities and determine the relation of hydrologic, edaphic, and geochemical gradients on community composition and spatial distribution among 18 vegetation, hydrology, and soil sampling points in Abe Run, a botanically unique poor fen in northeastern West Virginia. We also examined the interactions of disturbance with the physical environment and species composition. A total of 179 vascular plant species were identified from sample plots. Vegetative composition and structure, dominant soil texture, and hydrology lacked the distinct concentric zonation of northern peatlands; instead, all were patchy and varied considerably over short distances. Graminoid-forb meadows with primarily silt-loam mineral horizons, greater depth to groundwater, and fewer days of inundation characterized the lower reaches of the wetland. These plots were more acidic, with absent or shallow O horizons, and lower concentrations of soil base cations (Ca, Mg, K). In the upper reaches of the wetland, mixed herb-shrub-tree dominated communities were structurally and compositionally more complex; here, organic horizons were much more prominent, peat depth ranged from 80 to 100 cm, and the average depth to water table was 10 cm less than for wells in the lower reaches of the wetland. Plots from upper transects (3–6) tended to have more shrub and tree cover, and higher concentrations of soil base cations. Much of the variability among plots in the upper and lower reaches of the wetland are consistent with beaver inundation of a large portion of the wetland during the 1980s. Multiple-response permutation procedures verified the difference (P < 0.0001) between vegetation of plots in the lower and upper reaches of the watershed. Because fens are connected to groundwater, these habitats are particularly vulnerable to disturbances, particularly those that alter existing land use and land cover. Minimization of disturbances in the surrounding watershed, controls on an excessive deer population, removal of exotic, non-native species, and control on foot traffic are all integral to maintaining the integrity of this high-value wetland.     

A numerical phytosociological study of the summits of the majella massive (Italy)

Summary A phytosociological study of Majella's summits by the use of multivariate methods has allowed to discover the following new associations:Gnaphalio-Plantaginetum atratae on humocarbonatic soils in snowy depressions,Leontopodio-Elynetum on rendzina in wind exposed and stony places,Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani on protorendzina with gravel.Gnaphalio-Plantaginetum atratae andLeontopodio-Elynetum might be classified inElyno-Seslerietea, although the former presents character species ofSalicetea herbaceae; Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani are classified inThlaspidion stylosi (foeder. nova) ofThlaspidietea.Comparisons between some clustering methods and between ordination methods based on the mathematics of principal component analysis are discussed. The efficiency of sum of squares agglomeration when the plant communities vary in a continuum and the importance of a linearizing transformation in principal component analysis are stressed.The research was supported by a grant from the Italian CNR to Prof. D. Lausi. We wish to thank also Prof. L. Orlóci, Dr. E. van der Maarel and Prof. S. Pignatti for reading and discussing the text, and Mr. A. Zampar, S. Sedmak and T. Ubaldini for technical assistance.     

Halothiobacillus neapolitanus strain OSWA isolated from "The Old Sulphur Well" at Harrogate (Yorkshire, England)

The “Old Sulphur Well” has a subterranean input of water containing 5.5 mM total sulfide, which would be inhibitory to the growth of most bacteria. The obligately chemolithoautotrophic Halothiobacillus neapolitanus is a sulfur bacterium known to tolerate and metabolize high sulfide concentrations, and we report the isolation of H. neapolitanus strain OSWA from this source. Strain OSWA grows well on thiosulfate and tetrathionate as energy sources, and tolerates at least 5 mM sulfide. Its specific growth rates and yields in batch culture were 0.22 h⁻¹ and 5.3 g mol⁻¹ (thiosulfate), and 0.23 h⁻¹ and 9.5 g mol⁻¹ (tetrathionate). Its 16S rRNA gene sequence shows >99% identity to reference sequences of H. neapolitanus, and it shares morphological and physiological characteristics typical of the species. It is one of a very small number of strains of H. neapolitanus described to date, and the first to be isolated from an ancient sulfide-rich natural spa.     

A comparison of RAPD and isozyme analyses for determining the genetic relationships among Avena sterilis L. accessions

Isozyme analysis is a valuable tool for determining genetic relationships among breeding lines and populations. The recently developed DNA technologies which can assay a greater proportion of the plant genome are providing a plentiful array of additional genomic markers. The objective of this research was to compare random amplified polymorphic DNA (RAPD) versus isozyme-based estimation of relationships among 24 accessions of a hexaploid wild oat, Avena sterilis L. The accessions were evaluated for variation in 23 enzyme systems and by 21 10-mer primers. A total of 77 polymorphic isozyme bands and 115 polymorphic RAPD bands were observed. Two matrices of genetic distances were estimated based on band presence/ absence. These matrices were subsequently utilized in cluster analysis and principal coordinate analysis. Both isozymes and RAPDs were proficient at distinguishing between the 24 accessions. The correspondence between the elements of both distance matrices was moderate (r=0.36**). Nevertheless, the overall representation of relationships among accessions by cluster analysis and ordination was in considerable agreement. The two techniques contrasted most notably in pair-by-pair comparisons of relationships. RAPD analysis resulted in a more definitive separation of clusters of accessions. The most significant impact of the DNA-based markers probably will be the more accurate determination of relationships between accessions that are too close to be accurately differentiated by isozymes.The research reported in this publication was funded by the North Carolina Agricultural Research Service, the North Carolina Biotechnology Center, and by a Heisenberg Fellowship (HE 1497/3-2) provided by the German Research Council to Manfred Heun     

Analysis of the disintegrating group and gradient structure in Swiss riparian forests

The differentiation of river flood plain vegetation is predominantly determined by the inundation frequency and the type and age of the substrate. A comparison of data published in 1958 with recent relevés from all parts of Switzerland indicate that the hitherto known gradient- and group structure is disintegrating into multiple floristically isolated stands as a result of waterflow management constructions. In view of further vegetation mapping, a two-phase classification is proposed where the core of the gradients and groups is isolated and analysed first. The outliers are then re-attached to serve as possible indicators of the existence of variation not sufficiently described by the data. To structure the tedious analytical calculations involved, a hierarchical procedure has been developed.Abbreviations AOC = Analysis of concentration - CA = Correspondence analysis - PCA = Principal components analysis     

北京小龙门森林鸟类群落划分与生态分析

森林鸟类是森林陆栖脊椎动物中种类和数量最丰富的动物类群 ,它们对于促进森林天然更新、传播植物种子及花粉、控制森林害虫和害兽等方面都起着重要作用。关于小龙门林区鸟类群落结构的研究已有报道[1 ] ,但是对于小龙门林区鸟类群落的划分未见有专门报道 ,我们于 1 992年 1 0月～1 993年 2月 ,1 993年 4～ 1 2月 ,1 994年 2～ 8月对北京小龙门林区所有 8条自然沟和 1条公路进行了调查 ,目的在于了解小龙门林区不同林型、海拔等区域的鸟类种类组成和数量状况 ,探讨不同区域的鸟类群落的划分及其影响因素。1　研究地点及方法小龙门林区位于北…     

Prehistoric agriculture revealed by pollen analysis,plough-marks and sediment studies at Sola,south-western Norway

In 1985 archaeological excavations at Stavanger Airport, Sola, south-western Norway, revealed evidence for five phases of human activity ranging in age from the Mesolithic to the Late Bronze Age. The two youngest phases, namely 4 and 5 which reflect agrarian activity, are considered in detail in this paper. The fourth phase, which dates to ca. 3500 B.P., contains the first evidence of animal husbandry at the site and, in the fifth phase, there is evidence for a mixed farming economy. Physical evidence of cultivation includes intersecting patterns of plough-marks and, at seven sites, pollen assemblages indicative of arable farming have been recorded. The arable fields, in which weed-rich crops of Hordeum and Triticum were grown, date to ca. 2550-2200 B.P. The fields were subsequently covered by a thick layer of aeolian sand.     

Conformational studies of a monoclonal antibody, IgG1, by chemical oxidation: structural analysis by ultrahigh-pressure LC-electrospray ionization time-of-flight MS and multivariate data analysis

We describe the development of a method in which protein oxidation by H₂O₂ followed by ultrahigh-pressure liquid chromatography (UHPLC) coupled with electrospray ionization time-of-flight mass spectrometry (ESI-ToFMS) and multivariate analysis are used to detect alterations in conformational states of proteins. In the study reported here, an IgG1 monoclonal antibody in native and denatured conformational states was oxidized by treatment with hydrogen peroxide. Peptide fragments generated by tryptic digestion were then analyzed by UHPLC-ESI-ToFMS. After reducing noise and extracting peaks from the LC–MS data using MzExplorer, software developed in-house and based on Matlab, we were able to distinguish peptides arising from the native and denatured states of the oxidized protein by principal component analysis. Peptides containing residues, which are inclined to undergo oxidation, such as methionine, are founded to be particularly important in this approach. We believe that the methodology could facilitate attempts to characterize the conformational states of recombinant monoclonal antibodies and other proteins.     

Congenital defects of the upper lateral incisors: Multivariate analysis of measurements of the other teeth,the superior arch,head and face

The survey of a French male population allowed us to ascertain 75 propositi with one or two missing ULI, 59 propositi with one or two reduced ULI and 99 controls on whom measurements (mesiodistal and buccolingual diameters) of all teeth of the superior arch are available. Principal Component Analysis gave a first estimated principal component highly correlated with each of the dental measurements or arch measurements. This size factor was eliminated by observing the plane of the second and third principal components. Strikingly different clusters of MD diameters or BL diameters were observed for the controls, the propositi missing one or two of the ULI and the propositi with reduced ULI. For the controls, the arch length is correlated with the MD molar diameters and the MD incisor diameter, the arch width being isolated from the other measurements. For the propositi with missing ULI, among the dental measurements the MD and BL diameters cluster, the arch length is isolated as are the arch widths. For the propositi with reduced ULI, the arch length is closer to the dental measurements while the widths, especially the first one, are isolated. The best discriminant measurements are the diameters of the first premolars and the canine, the first arch width and the arch length. Among controls, the arch is narrowed and shorter for the propositi with absence and wider for the propositi with reduction. Teeth measurements are always smaller in propositi.     

Progressive plant invasion and colonization of an area adjacent to ancient woodland at Edford Wood, Somerset, England

Edford Wood, near Holcombe in Somerset, England has a rich and varied flora. Topography and species composition indicate that much of the woodland is of ancient origin. The history of the site is complex, with the woodland long subjected to considerable human disturbance from surface mining of coal, drainage and the felling of larger trees. Documentary and other evidence has revealed that part of the wood has developed from grassland during the present century. This area of secondary woodland illustrates processes of succession as woodland plants invade.     

Late-glacial and Holocene climate dynamics at the steppe/forest ecotone in southernmost Patagonia, Argentina: the pollen record from a fen near Brazo Sur, Lago Argentino

We present a pollen record from a fen at the eastern shore of Brazo Sur south of Lago Argentino, Argentina (core BRS 1/06, 50°34′54″S, 72°54′52″W, 198 m a.s.l.). The coring site is located in the transition zone from humid grass steppe to Andean Nothofagus forest. With the exception of a mid-Holocene sand layer, the record covers the interval between 13,350 and 1,700 cal b.p., indicating that there could have been no recurrence of Late-glacial conditions in Brazo Sur, as has been suggested in the literature as having been contemporary with the Younger Dryas interval in the northern hemisphere. The Late-glacial and early Holocene periods at Brazo Sur are characterized by fluctuations between humid grass-dominated steppe associations and drier ones dominated by Asteraceae and Ericaceae. At the start of the Holocene, the pollen influx increased. Nothofagus dominance began by 7,700 cal b.p. probably due to increasing moisture. Present-day closed Nothofagus forest developed around 2,500 cal b.p., related to a further increase in moisture.     

Size and age at sexual maturity of Atlantic argentine,Argentina silus: a critique

Synopsis A recent analysis of size and age at sexual maturity ofArgentina silus on the Scotian Shelf is invalid because field maturity stage data collected during the non-spawning, quiescent stage of the reproductive cycle were unreliable for distinguishing between immature and resting mature stages. Thus two-thirds of the data used must be discounted. Utilization of different length measurement criteria for different years, for which no correction is made, could introduce substantial error in length at maturity estimates based on the remaining data. Age data collections were restricted to one 12 month period and thus were inadequate to characterize age at maturity by 5 yr time periods as attempted in this analysis. No attempt is made in the analysis to determine whether available samples adequately represent the population with regard to maturity i.e. whether immature and mature fish of the same length had an equal probability of being sampled. It is demonstrated here that maturity ogives can differ greatly depending on assumptions made concerning the representativeness of samples. Many of the criticisms made are likely valid for a series of papers on maturity of Atlantic coast fishes by the same author.     

Spectrophotometric resolution of ternary mixtures of tryptophan, tyrosine, and histidine with the aid of principal component-artificial neural network models

A simple and sensitive spectrophotometric method to resolve ternary mixtures of tryptophan (Trp), tyrosine (Tyr), and histidine (His) in synthetic and water samples is described. It relies on the different kinetic rates of the analytes in their oxidative reaction with potassium ferricyanide (K(3)Fe(CN)(6)) in alkaline medium. The absorbance data were monitored on the analytical wavelength (420 nm) of K(3)Fe(CN)(6) spectrum. Synthetic mixtures of the three amino acids were analyzed, and the data obtained were processed by principal component-artificial neural network (PC-ANN) models. After reducing the number of spectral data using principal component analysis, an artificial neural network consisting of three layers of nodes was trained by applying a back-propagation learning rule. Tangent and sigmoidal transfer function were used in the hidden and output layers, respectively. The analytical performance of this method was characterized by relative standard error. The method allowed the determination of Trp, Tyr, and His at concentrations between 10 and 55, 10 and 60, and 10 and 40 microg ml(-1), respectively. The results show that the PC-ANN is an efficient method for prediction of the three analytes.     

Negative charge at the consensus sequence for the serum- and glucocorticoid-inducible kinase,SGK1, determines pH sensitivity of the renal outer medullary K+ channel,ROMK1

The renal outer medullary K(+)-channel ROMK1 is upregulated by the serum- and glucocorticoid-inducible kinase SGK1, an effect potentiated by Na(+)/H(+)-exchanger-regulating-factor NHERF2. SGK1 phosphorylates ROMK1 at serine44. To explore the role of SGK1 phosphorylation, serine44 was replaced by an alanine ([S44A]ROMK1) or an aspartate ([S44D]ROMK1). Wild type ROMK1, [S44A]ROMK1, and [S44D]ROMK1 were expressed in Xenopus oocytes with or without constitutively active [S422D]SGK1 and NHERF2, and K(+) current (I(KR)) determined. Cytosolic pH required for halfmaximal I(KR) (pK(a)) amounted to 7.05+/-0.01 for ROMK1, 7.07+/-0.02 for [S44A]ROMK1, and 6.83+/-0.05 for [S44D]ROMK1. Maximal I(KR) was [S44D]ROMK1>wild type ROMK1>[S44A]ROMK1. Coexpression of [S422D]SGK1 and NHERF2 enhanced the activity of ROMK1, [S44A]ROMK1 and [S44D]ROMK1, but led to a significant shift of pK(a) only in wild type ROMK1 (6.95+/-0.03). In conclusion, phosphorylation by SGK1 or introduction of a negative charge at serine44 shifts the pH sensitivity of the channel and contributes to the stimulation of maximal channel activity by the kinase.     

Modelling multiple ovulation,fertilization, and embryo loss in human fertility studies

Models of human fertility that incorporate information on timing of intercourse have assumed that a single ovum is released each menstrual cycle. These models are misspecified if two or more viable ova are sometimes released in a single cycle, which is known to occur in dizygotic twin pregnancies. In this paper, we propose a model for multiple ovulation in humans. We assume that the unobservable number of viable ova in each cycle follows a multinomial distribution. Successful fertilization of each ovum depends on the ability of the cycle to support a pregnancy and on the aggregate of a set of unobservable Bernoulli trials representing the fertilizing effects of intercourse on various days. Our model accommodates general covariate effects, allows for heterogeneity among couples, and accounts for a sterile subpopulation of couples. Information on early detection of pregnancy can be incorporated to estimate the probability of embryo loss. We outline a Markov chain Monte Carlo algorithm for estimation of the posterior distributions of the parameters. The methods are applied to data from a North Carolina pregnancy study, and applications to studies of assisted reproduction are described.     

Age and growth studies of chondrichthyan fishes: the need for consistency in terminology, verification, validation, and growth function fitting

Validated age and growth estimates are important for constructing age-structured population dynamic models of chondrichthyan fishes, especially those which are exploited. We review age and growth studies of chondrichthyan fishes, using 28 recent studies to identify areas where improvements can be made in describing the characteristics of ageing structures (both traditional and novel) utilized to estimate ages of sharks, rays, and chimaeras. The topics identified that need consistency include the: (1) terminology used to describe growth features; (2) methods used to both verify and validate age estimates from chondrichthyan calcified structures, especially edge and marginal increment analyses; and (3) the functions used to produce and describe growth parameters, stressing the incorporation of size at birth (L ₀) and multiple functions to characterize growth characteristics, age at maturity and longevity.     

Ordination and classification in the upland Rugege forest (Rwanda,Central Africa)

Summary Quantitative data on habitat and vegetation from 42 releves of the Rugege forest have been submitted to different ordination and classification methods.The habitat factors which have an important effect upon vegetation are: hydromorphy, abundance of tree layer and depth of soil.The different ordination (principal components analysis and reciprocal averaging) and numerical classification methods applied to the same set of data lead to consistent results. The numerical classification seems better than the Braun-Blanquet's method.Four groupings have been defined.The future developments of ecological studies in the Rugege forest are discussed in relation to the forest conservation.All data presented in this work were collected during my stay in the National Institute of Scientific Research of Rwanda, 1971 – 1972. Part of the computations (numerical analysis and principal components analysis) was carried out at the Nijmegen University's IBM 370/155; I am happy to thank Dr. E. van der Maarel and Dr. J.G.M. Janssen for their welcome and assistance. The reciprocal averaging ordinations and the principal components analysis on the basis of correlation between relevés were performed on the Louvain-La-Neuve University's IBM 370/158; I am very grateful to Professeur Berthet for this important assistance.This paper corresponds to part of a thesis presented at the Liège University on 7th November 1973.     

Synthesis, single crystal structure and DNA cleavage studies on first N-ethyl substituted three coordinate copper(I) complex of thiosemicarbazone

A copper(I) complex [Cu(CETH)₂Cl] (Ia), where CETH = cuminaldehyde-4-ethyl-3-thiosemicarbazone (I), is prepared and structurally characterised. The complex crystallizes in orthorhombic space group pna2(1) with the unit cell parameters; a = 9.8598(14) Å, b = 15.411(2) Å, c = 0.817(3) Å, V = 2055.9(4) Å³ and Z = 4. The neutral complex has the copper(I) centre bonded to two thioketonic sulphur donor in η¹-S bonding mode and one chloride giving ‘Y’ shape geometry. The complex is diamagnetic and exhibits a copper to ligand charge transfer bands at 351 and 398 nm in dimethylformamide. The complex shows quasireversible cyclic voltammetric response at 0.41 V (ΔEp = 300 mV) at 50 mVS⁻¹ in DMF for the Cu(II)/Cu(I) oxidation couple. Complex Ia shows marginal nuclease activity with pUC18 DNA in the presence of reducing agent (Dithiotretal) and hydrogen peroxide.