bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Temperature in the Entanglement Kinetics of a Polymer Melt
Authors: Jeyaseelan R. S. , Giacomin A. J.
Published: February 2008

Large-amplitude oscillatory shear (LAOS) experiments were conducted at different temperatures on a molten low-density polyethylene standard, designated IUPAC LDPE X. Jeyaseelan et al. (1993) have successfully employed a simplification of transient network theory to describe the LAOS behavior of this polymer melt, at 150°C. The transient network is described by two kinetic rate constants, one for the formation of entanglements due to Brownian motion (k1), and another for the destruction of entanglements (k2) due to the imposed deformation. Upon comparison of the predictions of this transient network theory with the measured LAOS behavior of this polymer, we find that the kinetic rate constants k1 and k2 are invariant in the range of temperatures examined (150 to 190°C). The temperature dependence of departures from linear viscoelasticity is fully accounted for in the equilibrium entanglement kinetics.
Tension of Conductor Under Concentrated Loads
Authors: Yu P. , Wong P. S. , Kaempffer F.
Published: February 2008

A common difficulty in the analysis and design of transmission and distribution lines is to determine a conductor’s tension and its static profile under concentrated loads. For relatively small concentrated loads (such as detuning pendulums on transmission lines), approximation methods may give good predictions. For large concentrated loads (such as fallen trees on distribution lines), however, exact solutions must be found. This paper presents methodologies to compute conductor tension and static profile in three-dimensional space using both approximate and exact solution procedures under concentrated loads with different boundary conditions. Practical engineering examples from galloping control of transmission lines and mechanical coordination of distribution lines are given to demonstrate the applicability of the theory.
On Young’s Modulus for Anisotropic Media
Authors: Boulanger P. , Hayes M.
Published: February 2008

If a piece of homogeneous anisotropic elastic material is subject to simple tension along a direction n for which Young’s modulus E(n) is an extremum, then the corresponding strain field is coaxial with the simple tension stress field. An appropriate set of rectangular cartesian coordinate axes may be introduced such that three of the elastic compliances are zero. In this coordinate system the displacement field may be written explicitly and corresponds to a pure homogeneous deformation.
Peroxidase activity during adventitious root formation in avocado microcuttings
Authors: García-Gómez Maria Luisa , Sánchez-Romero Carolina , Heredia Antonio , Pliego-Alfaro Fernando , Barceló-Muñoz Araceli
Published: February 2008

Peroxidases seem to play an important role in the regulation of auxin levels during the rooting of cuttings. In avocado, leaf peroxidase activity remained constant throughout the rooting process in the three fractions analyzed (soluble, ionically, and covalently bound to cell wall). Soluble peroxidase activity in stem basal parts increased twofold after 3 days and then remained constant until the end of the process. Cationic and anionic electrophoresis revealed a lower number of isoenzymes in the stems than in the leaves. Histological stainings at stem basal parts were also carried out to localize the enzyme activity. Peroxidase was active in all tissues at the time the cutting was taken, with vascular bundles and epidermis giving the strongest reactions. During the process of root formation peroxidase activity was closely associated with growth and differentiation processes, e.g., cambial cell division and xylogenesis; a strong reaction was also found in the developing root primordia. The possible role of peroxidases in the regulation of auxin levels during the rooting process in avocado is discussed. Key words: auxin, avocado, peroxidase, rooting.
Chronologie du développement du fruit en relation avec la croissance végétative chez l'abricotier Prunus armeniaca L. cv. Rouge du Roussillon
Authors: Costes E. , Jaffuel S. , Audubert A. , Jay M. , Lichou J. , Demene M. N.
Published: February 2008

The chronology of fruit development and vegetative growth is described for the apricot cultivar 'Rouge de Roussillon'. We observed a synchrony between the major events of fruit development and those of vegetative growth. This allows us to complete a descriptioon of phases in fruit by taking in account the unfurling of preformed, then newly formed parts of growth units (GU). During the first period, which lasts approximately 12 days following full flowering, numerous events unfold simultaneously. In the absence of leaves, everything the tree produces during this period depends on its reserves. During the second period (from around 12 to 30 days) cell division ceases in the future fruit and the preformed parts of the growth units unfurl. From 30 to 60 days after full flowering, the fruit develops little, while the neoformed parts of the growth units are formed. The cessation of growth is spread out at intervals during this period and, at 60 days, 80% of GU have ceased to grow. The embryo continues its development until about 90 days, while the number of growing shoots is limited. Finally, beyond 90 days, the fruit finishes its enlargement while new growth units appear on the tree. The period of direct concurrence between vegetative and floral development seems limited to the two early periods. In effect, the preformed leaves in the winter bud seem to be incapable of providing assimilates to all the growing organs. Consequently, the priority is alternatively vegetative growth (unfurling of newly formed leaves) then fruit development. Key words: apricot, embryogenesis, growth, flowering, fruit development. [Journal translation]
Étude expérimentale de la ramification acrotone d’un Pelargonium ligneux (géranium rosat)
Authors: Vincent Grégoire
Published: February 2008

Acrotonie branching refers to the superior development of distal axillary shoots along the supporting branch. Although acrotony is quite common the underlying physiological mechanisms remain unknown. A careful study of the acrotonic growth habit of "géranium rosat" in various conditions allows one to distinguish three components. The first two are consequences of fixed gradients of growth potential that seem to set up at an early stage of ontogeny. They are tightly related to the morphogenetical sequence of initiation of the successive meristems. The third component is more variable and is probably related to competition for light due to mutual shading. Key words: branching, acrotony, Pelargonium, géranium rosat.
A numerical taxonomic study of Armeria maritima (Plumbaginaceae) in North America and Greenland
Authors: Lefèbvre Claude , Vekemans Xavier
Published: February 2008

Principal components analysis, discriminant analysis, cluster analysis and two level nested analysis of variance were performed on 961 herbarium specimens of Armeria maritima covering the complete geographic range of the species in North America and Greenland. Among the monomorphic, self-compatible specimens combining coarsely reticulate pollen and papillous stigma, we recognized three subspecies. Along the Pacific coast from California to Vancouver Island, the single taxon ssp. californica is proposed, which includes the formerly described var. purpurea. In arctic and subarctic regions, ssp. sibirica, which includes var. labradorica, and ssp. interior are recognized as distinct entities. The latter has a restricted distribution and can be easily distinguished morphologically owing to its glabrous calyces. The morphological variation between ssp. californica and ssp. sibirica is continuous and some overlap occurs. The best diagnostic characters are two ratios: sheath length to flower head width and outer involucral bract length to flower head width. Geographic trends are obvious: a reduction in plant size with increasing latitude and an increase in frequency from west to east of hairy scapes and holotrichous calyces. The dimorphic and self-incompatible ssp. maritima is maintained because of its distinct breeding system (papillate stigma associated with finely reticulate pollen and smooth stigma associated with coarsely reticulate pollen). Subspecies maritima is only found in south Greenland and some specimens are morphologically similar to eastern monomorphic plants. Key words: Armeria maritima, North America, numerical taxonomy.
Interpreting variability among isolates of Macrophomina phaseolina in pathogenicity, pycnidium production, and chlorate utilization
Authors: Mihail J. D. , Taylor S. J.
Published: February 2008

One hundred and fourteen isolates of Macrophomina phaseolina from tissue of hosts in the Asteraceae, Euphorbiaceae, Fabaceae, and Poaceae, and from cultivated and noncultivated soils in Somalia (east Africa) and Arizona were tested for pathogenicity, ability to form pycnidia, and chlorate-utilization phenotype. Hyphal interactions of pairs of isolates from noncultivated soils in Somalia and Arizona were examined to address the possibility of genetic reproductive isolation of two geographically separated populations. Isolates from the Poaceae were less pathogenic and formed pycnidia less frequently compared with isolates from dicot host tissue. Chlorate-utilization phenotype was unrelated to host tissue source. However, isolates that infrequently or never produced pycnidia were more likely to have chlorate-sensitive phenotypes. Apparently successful hyphal fusions were observed for 64.3% of confrontations where one isolate was taken from Arizona and one was from Somalia, implying no barrier to genetic interchange at this initial level of interaction. While M. phaseolina is a heterogeneous species that cannot be partitioned into distinct subspecific groups based upon function, it appears that isolates colonizing the Poaceae are more restricted in pathogenicity than the general population. Key words: chlorate utilization, geographic isolation, host specialization, hyphal interactions, Macrophomina phaseolina.
Local and regional vegetation change on the northeastern Olympic Peninsula during the Holocene
Authors: McLachlan J. S. , Brubaker L. B.
Published: February 2008

The postglacial vegetation history of the northeastern Olympic Peninsula was investigated at different spatial scales by comparing the pollen, macrofossil, and charcoal records from a low elevation lake (Crocker Lake) and a nearby forested swamp (Cedar Swamp). The regional pollen record from Crocker Lake revealed a parkland of coniferous species with divergent modern ecological tolerances, including Pinus contorta, Picea sitchensis, and Abies lasiocarpa during the late glacial period (~ 13 000 – 10 000 BP). Disturbance-adapted species such as Alnus rubra and Pseudotsuga menziesii dominated forests during the early Holocene (10 000 – 7000 BP). Modern forests containing mesic late-successional species such as Tsuga heterophylla and Thuja plicata were established during the late Holocene (7000 BP to present). During the late glacial period, the local vegetation at Cedar Swamp was dominated by Alnus sinuata. Hydrologic changes resulted in the establishment of a deep marsh during the early Holocene. Hydrosere succession from an open aquatic environment to a forested wetland and disturbance-mediated alternations between Thuja plicata and Alnus rubra characterized the local vegetation during the late Holocene. Throughout the Holocene, the vegetation of the northeastern Olympic Peninsula was governed by broad climatic and physiographic parameters at the regional scale and the effects of local geomorphologic constraints and disturbance history at the finer landscape scale. Key words: fossil pollen, vegetation history, Olympic Peninsula, Quaternary.
Native prairie grasses and microbial community responses to reclamation of taconite iron ore tailing
Authors: Noyd Robert K. , Pfleger F. L. , Norland Michael R. , Sadowsky Michael J.
Published: February 2008

The effect of reclamation treatments on seeded native grass cover and species composition, soil microbial biomass carbon, and populations of actinomycetes, fungi, free-living N2-fixing bacteria, and aerobic heterotrophic bacteria was compared in field plots in coarse taconite tailing. Reclamation treatments consisted of all possible combinations of three rates of composed yard waste, three rates of fertilizer, and inoculation with arbuscular mycorrhizal fungi. Composted yard waste increased plant cover, soil microbial biomass, and populations of all groups of microorganisms compared with unamended, non-inoculated control plots. Microbial populations and biomass in tailing plots were low compared with natural soils and were correlated with plant cover and available P. Mycorrhizal inoculation resulted in a 6% increase in plant cover, although this was not significant, and significantly enhanced N2-fixer populations in June but did not affect other groups of microorganisms. There were no differences between moderate and high rates of composted yard waste. We conclude that incorporation of a moderate rate of organic matter can ameliorate the stressful conditions of coarse taconite tailing and can enhance the initiation of a functional soil ecosystem able to support the establishment of seeded native prairie grasses and may provide a long-term solution to reclamation of taconite tailing. Key words: arbuscular mycorrhizal fungi, mine reclamation, soil microorganisms, composted yard waste.
Isolation and characterization ofCryphonectria parasiticamutants that mimic a specific effect of hypovirulence-associated dsRNA on laccase activity
Authors: Rigling Daniel
Published: February 2008

Hypovirulent, double-stranded (ds) RNA-containing strains of the chestnut blight fungus Cryphonectria parasitica were previously shown to produce less laccase activity than virulent strains when grown on malt extract agar containing tannic acid (Bavendamm reaction). Three mutants that lacked this specific laccase activity were selected after UV mutagenesis of a dsRNA-free, wild-type strain. Complementation tests and sexual crosses showed that all mutations were recessive, two were allelic (lacR1-1 and lacR1-2), and one (lacR2) was nonallelic. No linkage was detected between the two loci. None of the known C. parasitica laccases (LAC1, LAC2, and LAC3) was substantially reduced in the lacR1 mutants. The lacR2 mutant, in contrast, produced about 10-fold less extracellular LAC1 and LAC3 activities than the wild-type strain. Intracellular LAC2 was reduced to about 50% in this mutant. These results suggest a role for both LAC1 and LAC3 in the Bavendamm reaction. The three mutations had no significant effect on fungal virulence, pigmentation, and sporulation, all phenotypes that were suppressed in an isogenic dsRNA-containing strain. Key words: Endothia parasitica, genetics, hypovirulence, dsRNA, chestnut blight.
Development of primary branches and crown profile of Fraxinusexcelsior
Authors: Cluzeau Catherine , Goff Noel Le , Ottorini Jean-Marc
Published: February 2008

The relationship between stem and branch growth of common ash (Fraxinusexcelsior L.) was studied from cumulated annual increments of stems and branches determined by stem and branch analysis on 19 unforked trees aged 12–60 years. An allometric relationship between branch length and cumulated stem growth above the branch base was modified to account for an additional tree height effect, and fitted to the pooled branch and stem data. The crown dimensions of trees were derived from the branch growth equation and an average mean branching angle, by solving a crown radius equation. This crown profile prediction method was checked individually on tree samples by comparing observed and simulated crown radii; satisfying results were obtained, except for some trees that were suppressed for a long period.
Stock and stand tables for point, double sampling with a ratio of means estimator
Authors: Oderwald Richard G.
Published: February 2008

A method is proposed for adjusting small-sample-based stock and stand table entries from point, double sampling with a ratio of means estimator. The proposed adjustment uses the characteristics of the ratio of means estimator, ensures that totals from the stock and stand tables match the large sample estimates, and preserves the volume–basal area ratio by DBH class before and after adjustment. Bias and variance estimates for the adjusted stock table entries are presented.
Effects of live tree fumigation on nontarget vegetation
Authors: Luoma Daniel L. , Thies Walter G.
Published: February 2008

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees, both healthy and infected by Inonotussulphurascens (Pilát) M.J. Larsen, F.F. Lombard, & J.W. Clark (Phellinusweirii sensu lato), were fumigated with chloropicrin or methylisothiocyanate at a site in the Oregon Coast Range. Ten growing seasons later, vegetation cover on plots around treated and untreated individuals was evaluated to determine fumigant effects on nontarget plants. Total plant cover and individual species cover for Berberisnervosa Pursh and Stokesiellaoregana (Sull.) Robins were significantly reduced in the chloropicrin treatment plots. The dominant shrub, Gaultheriashallon Pursh, was little affected in chloropicrin plots. Slightly greater species richness and Rubusursinus Cham. & Schlecht. cover in chloropicrin plots were attributed to higher light levels and other factors associated with reduced shrub cover on the treated plots. Multivariate analysis showed little overlap in plant community structure between chloropicrin-treated and control plots. Detection of effects due to the methylisothiocyanate treatment was hindered by the lack of strictly paired control trees. The results are discussed in relation to the retrospective nature of the study.
Relation between genetic diversity and pollution impact in a 1912 experiment with East European Pinussylvestris provenances
Authors: Oleksyn J. , Prus-Glowacki W. , Giertych M. , Reich P.B.
Published: February 2008

Results are presented of genetic variation and growth decline due to pollution for 11 European populations, 1 Turkish population, and 1 Siberian population of Scots pine (Pinussylvestris L.) growing in a provenance experiment established in 1912 in Pulawy, southeastern Poland. Since 1966 this area has been subjected to acute pollution from a nitrogen-fertilizer factory emitting high levels of SO2, NOx, NH3, and other toxic compounds. A significant negative correlation was found between genotype polymorphism indices and radial growth decline since 1966 assessed using tree-ring analysis (r = −0.58, P = 0.04). Populations with the highest values for genotype polymorphism index, numbers of alleles per locus, and numbers of genotypes per locus exhibited less of a decline in radial growth than those populations with lower values for these parameters. The results provide experimental support for the hypothesis that genetically richer populations are better adapted to changing conditions and suggest that such populations are less sensitive to air pollution in terms of growth reduction.
Distribution of coarse woody debris in a mountain stream, western Cascade Range, Oregon
Authors: Nakamura Futoshi , Swanson Frederick J.
Published: February 2008

The distribution of coarse woody debris in a fifth-order Cascade Range (Oregon) stream system was examined from a geomorphic point of view. The number, volume, location, orientation, decay class, and pool formation roles of coarse woody debris were investigated. The processes of coarse woody debris production, transport, and storage, which vary with channel and valley floor geomorphology, are responsible for the pattern of coarse woody debris distribution on valley floors. Channel width and sinuosity are the main factors that control production, storage sites, and hydrologic effects of coarse woody debris. The amount of coarse woody debris and the number of pool-forming pieces are relatively high in wide, sinuous reaches, where a complex structure of floodplains and riparian forests develops in association with a braided channel pattern. These relations are transferable to other systems with similar relations of coarse woody debris piece length to channel width.
Osmotic adjustment and its use as a selection criterion in Eucalyptus seedlings
Authors: Lemcoff Jorge H. , Guarnaschelli Ana B. , Garau Ana M. , Bascialli María E. , Ghersa Claudio M.
Published: February 2008

Osmotic adjustment was studied in 6-month-old seedlings of Eucalyptuscamaldulensis Dehnh., Eucalyptustereticornis Smith, Eucalyptusviminalis Labill., and Eucalyptusgrandis Hill ex Maiden. Because osmotic adjustment is related to water-stress tolerance, it can be used as a selection criterion of material adapted to drought. Half of the individuals of each species were submitted gradually to water stress, while the rest were maintained in soil at field capacity. Twenty-five days later the effect of stress on the development of osmotic adjustment was analyzed. All species had adjusted osmotically. The lowest osmotic adjustment was observed in E. camaldulensis and E. grandis (14.1% and 15.2%, respectively). Eucalyptusviminalis and E. tereticornis had values of 32.3% and 41.9%, respectively. Our results demonstrate that species differ significantly in their extent of osmotic adjustment under drought stress, and that it is possible to use this inductive plant feature as one of the criteria to select, during early developmental stages, Eucalyptus genotypes adapted to drought-prone environments. Some phylogenetic considerations are presented.
Transient chimeric gene expression in pollen of five conifer species following microparticle bombardment
Authors: Hay Irene , Lachance Denis , Aderkas Patrick Von , Charest Pierre J.
Published: February 2008

Mature pollen of lodgepole pine (Pinusconcorta Dougl.), yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach), western hemlock (Tsugaheterophylla (Raf.) Sarg.), jack pine (Pinusbanksiana Lamb.), and black spruce (Piceamariana (Mill.) B.S.P.) was bombarded with gold particles coated with four different plasmid constructions, pRT99GUS, pBM113Kp, pAct1-D, and pGA984, using the biolistic PDS-1000/He device. A protocol was devised for efficient gene transfer and gene expression assay in pollen. False positive results for expression of the β-glucuronidase (GUS) gene assayed with the substrate X-glucuronide were observed with pollen of yellow cypress, western hemlock, and lodgepole pine. The highest levels of transient GUS gene expression were obtained with plasmid pBM113Kp, which carried the GUS gene under the control of the wheat abscisic acid inducible early methionine promoter. The plasmids pRT99GUS (35S promoter) and pAct1-D (rice actin promoter) yielded similar intermediate levels of transient GUS gene expression. The pollen-specific promoter of the α-tubulin gene from Arabidopsisthaliana (pGA984) yielded the lowest levels of gene expression in pollen. Of the four species, yellow cypress showed the lowest levels of transient GUS gene expression and black spruce yielded the highest levels. The neomycin phosphotransferase II (NPT II) gene was also tested as a reporter gene for pollen transformation and was easily assayed via ELISA. The fusion gene between NPT II and GUS genes was detected at a lower level than the nonfused NPT II gene when under the control of the same 35S promoter. The method devised here could be used for the study of tissue-specific gene expression in conifer pollen.
Effects of carbon and lime additions on mineralization of C and N in humus from cutovers of western red cedar–western hemlock forests on northern Vancouver Island
Authors: Prescott C.E. , McDonald M.A.
Published: February 2008

The potential for amendments of simple C compounds or lime to improve N availability in humus from cedar–hemlock cutovers was tested in laboratory incubations and a greenhouse bioassay. Rates of C and N mineralization in samples of humus and woody humus during aerobic incubations in the laboratory were not affected by additions of potato starch. Mineralization of C was stimulated and net N mineralization was reduced after glucose addition. Microorganisms in humus may not be capable of degrading starch, and simpler C sources such as glucose increase immobilization of N in microbial biomass. The biomass of seedlings of western red cedar (Thujaplicata Donn), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Sitka spruce (Piceasitchensis (Bong.) Carr.) grown in pots containing cedar–hemlock humus amended with dolomitic lime was similar to the biomass of seedlings grown in unamended humus after 18 months. Seedlings grown in humus amended with N and P fertilizers were significantly larger than those grown in unamended or lime-amended humus. It is unlikely that applications of C or lime to cedar–hemlock cutovers would increase rates of N mineralization from humus. Additions of nutrients appear to be the only practical means of alleviating the nutrient supply problems on these sites.
Loblolly pine regeneration and competing vegetation 5 years after implementing uneven-aged silviculture
Authors: Shelton Michael G. , Murphy Paul A.
Published: February 2008

The effects of three basal areas (9.2, 13.8, and 18.4 m2/ha), maximum diameters (30.5, 40.6, and 50.8 cm), and site indices (≤24.6, 24.7–27.4, and ≥27.5 m at 50 years) on establishment and development of loblolly pine (Pinustaeda L.) regeneration and competing vegetation were determined on 81 permanent, 0.20-ha plots in south Arkansas and north Louisiana. Plots were harvested to the designated basal areas, maximum diameters, and a q-factor of 1.2 using the single-tree selection method during 1983 (a bumper seed year) and 1985 (a seed year failure); this necessitated including the year of harvest as a fourth variable. Pine regeneration and competing vegetation were evaluated 4 or 5 years after treatment. Models were developed to predict the number and percent stocking of pine seedlings and saplings and the percent coverage of competing vegetation. Fit indices ranged from 0.21 to 0.52 for pine regeneration and from 0.15 to 0.73 for coverage of competing vegetation. Pine regeneration was generally greatest for the 1983 harvest, the largest maximum diameters, and the poorest sites. Coverage for vines, hardwoods, and total vegetation was greatest on the good sites and generally for the lowest basal areas. Coverage of grasses, herbs, and shrubs did not vary significantly among treatments. Results suggest that seed production and competing vegetation influence the initial amounts of loblolly pine regeneration obtained with uneven-aged silviculture using single-tree selection.
Efficacy of antiaggregants for the pine engraver, Ipspini (Coleoptera: Scolytidae)
Authors: Devlin D.R. , Borden J.H.
Published: February 2008

The responses of pine engravers, Ipspini (Say), in British Columbia to ipsdienol-baited traps containing low, medium, and high dose rates of the antiaggregants verbenone and ipsenol, released from impregnated polyethylene and polypropylene beads, respectively, remained significantly lower than responses to ipsdienol-baited control traps throughout the spring. During the summer, the responses remained low only in traps containing medium and high dose rates of impregnated beads. Antiaggregant treatment densities of 100 and 400 bubble cap release points per hectare reduced the numbers of pine engravers caught in ipsdienol-baited, multiple-funnel traps by 66.1 and 76.8%, respectively. In 50 × 50 m thinning-simulation plots treated with a broadcast distribution of antiaggregant-impregnated beads in 1990, 32.9% of the felled lodgepole pines, Pinuscontorta Dougl., were attacked; in untreated control plots, 53.1% were attacked. The mean attack density per square metre of available bark surface in the treated plots (1.3) was significantly lower than that in the untreated plots (1.9); however, where attack occurred there was no difference (8.8 and 9.4 attacks/m2, respectively). In a 1991 experiment, verbenone- and ipsenol-impregnated beads were applied to 15 × 15 m thinning-simulation plots at initial release rates of 2.5 mg of verbenone and 0.05 mg of ipsenol per square metre of ground surface per day, and at double these rates. For three treatments, low and high rates 3 weeks prior to the first attack by I. pini and a high rate 2 weeks prior to attack, the mean attacks per square metre of available bark surface per week were reduced by 77.1, 82.9, and 97.1%, respectively, compared with attacks on felled pines in untreated control plots. The results of these experiments suggest that a timely application of broadcast antiaggregants would prevent the development of an outbreak population of I. pini.
Root freezing tolerance and vitality of Norway spruce and Scots pine seedlings; influence of storage duration, storage temperature, and prestorage root freezing
Authors: Lindström Anders , Stattin Eva
Published: February 2008

This study investigated the effect of different cold storage conditions on (i) root freezing tolerance of Norway spruce (Piceaabies (L.) Karst.) and Scots pine (Pinussylvestris L.) and (ii) the vitality of seedlings that suffered freezing injury to roots prior to storage. Container-grown seedlings, 1 year old, were stored from the end of October to April in three environments with different root temperatures: outdoor storage (−0.5 to 11.0 °C), cool storage (0.7 to 3.7 °C), or frozen storage (−5.0 to −3.8 °C). Root freezing tolerance was determined prior to storage in October and during storage in January and March. Maximum root freezing tolerance for both species occurred in January, when over 50% of spruce and pine seedlings survived 2 h exposure to −25 and −20 °C, respectively. At this time, roots of frozen-stored spruce were significantly more freezing tolerant than outdoor-stored seedlings, whereas storage environment had no significant effect on pine. Freezing tolerance in roots of both species decreased from January to March in all test environments but to a lesser extent at the subzero temperatures in the frozen storage. Root freezing to −10, −15, or −20 °C in late October before storage resulted in reduced poststorage survival of seedlings in April. Pine was more adversely affected (0–13% survival) than spruce (0–85% survival). Freezing of roots prior to storage caused the lowest survival with frozen storage.
Role of glutathione on recovery of red-osier dogwood plants from "near-lethal" heat stress
Authors: Shirazi A.M. , Siller-Cepeda J.H. , Fuchigami L.H.
Published: February 2008

not available
Black spruce somatic embryo germination and desiccation tolerance. II. Effect of an abscisic acid treatment on protein synthesis
Authors: Beardmore Tannis , Charest Pierre J.
Published: February 2008

In this paper, the biochemical changes associated with a 20 μM abscisic acid (ABA) and desiccation treatment on mature black spruce somatic embryos (SEs) were examined. It was previously shown that this ABA treatment of black spruce SEs resulted in an earlier, more uniform germination (i.e., root and shoot growth synchrony) and increased SE tolerance to slow and fast desiccation. In this paper, mature SEs (control SEs) were either placed on maturation media containing 20 μM ABA for 7 days (ABA-treated SEs) or placed on maturation media for 7 days without ABA (control–ABA SEs). Only the ABA treatment resulted in an increased SE protein content, dry mass, and SE ABA content compared with the control SEs. The ABA treatment was the only treatment that maintained a high percent germination following slow desiccation. Seven proteins with molecular mass of 42-, 33-, 32-, 28-, 27-, 21-, and 20-kDa were identified as storage proteins. An examination of in vivo protein synthesis showed that storage protein synthesis occurred in control SEs, ABA-treated SEs, and control –ABA SEs. There were minor changes, such as a cessation or decline in storage protein synthesis, in the ABA-treated and control –ABA SEs. Protein isolated from the treated and control SEs was probed with an antibody raised to the maize dehydrin. This antibody reacted strongly to a 23-kDa protein and reacted slightly to three other proteins in mature zygotic and somatic embryos and in all treated SEs. The ABA-treated SEs appeared to have a slightly elevated quantity of the 23-kDa dehydrin-like protein (based on intensity of the band in the Western blot). Desiccation of these SEs resulted in a decline in this protein to a level similar to that found in the controls. The ABA treatment induced the synthesis of two low molecular mass proteins (12- and 8-kDa) and their synthesis continued after these somatic embryos were desiccated. The synthesis of the 8-kDa protein was induced when control SEs were desiccated. These results suggest that the ABA treatment extended the maturation stage of development of the black spruce SEs and resulted in an increase in a dehydrin-like protein.
Effets des coupes d'éclaircie et des variations climatiques interannuelles sur la production et la teneur en sucre de la sève d'une érablière
Authors: Pothier David
Published: February 2008

A study was initiated in 1975 on a sugar maple (Acersaccharum Marsh.) stand of the Station forestière de Duchesnay (46°57′N, 71°39′W) to determine the effect of thinning on sap production of sugar maple. From 1975 to 1989, spring sap flow and sugar concentration were measured in 58 sample plots distributed in five blocks within which three intensities of thinning (0, 22, and 35% of the initial basal area) were applied. Thinning intensities only accounted for a small part of the variation in sap volume per tap and sap sugar concentration. However, more than 60% of the variation of these two sap characteristics was related to year-to-year variations. This suggests that sap yield and sap sugar concentration were largely controlled by the different climatic conditions that occurred during these years. Hence, sap yield was strongly correlated with the number of days characterized by temperature fluctuations around 0 °C during springtime and by winter precipitation. Sap sugar concentration was also correlated to the number of days with temperature fluctuating around 0 °C during springtime but all other tested meteorological variables failed to improve this relationship. While thinning intensities did not affect sap yield per tap and sugar concentration, sugar yield per hectare could be improved by thinning over the long term since it increased the potential number of taps per hectare.
Characterizing spatial structure of forest landscapes
Authors: Baskent Emin Z. , Jordan Glen A
Published: February 2008

Forest landscape management is based on the premise that resource flows as well as biodiversity levels and ecosystem processes are determined by the array and spatial arrangement of forest conditions, i.e., spatial structure, and its change over time. This paper points out that a quantitative basis for measuring spatial structure is a prerequisite to implementing forest landscape management. Without such, structural objectives cannot be established nor can the understanding of spatial dynamics necessary to achieve structural objectives be mastered. This paper presents a comprehensive collection of measurements, some old and some new, organized in a hierarchical framework. The framework organizes structural measurements by geographical scale, i.e., landscape and patch, and within these by areal, lineal, and topological categories. The hierarchical framework is offered as a means to simplify interpretation of a rather large and complex set of measurements. Using this framework, the paper presents more than two dozen measurements. In each case, the measurements are discussed in terms of calculation algorithm, interpretation, and timber and (or) wildlife habitat context. The potential use of the measurements for quantifying landscape structure is demonstrated with an example. The paper concludes with a general discussion of the implications of the measurements presented for forest landscape management.
Dynamics of ovarian follicle formation in the musk shrew (Suncus murinus L.) from birth to adulthood
Authors: Mohanty N. , Chainy G. B. N.
Published: February 2008

To understand the kinetics of ovarian follicular development in the musk shrew Suncus murinus L., the growth of follicles was studied from birth to adulthood. Six distinct types of normal follicles are described on the basis of follicular diameter (FD): class 1 (FD < 109 μm, where epitheloid cells of the theca are not differentiated); class 2 (FD between 100 and 150 μm); class 3 (FD between > 150 and 200 μm); class 4 (FD between > 200 and 250 μm); class 5 (FD between > 250 and 300 μm); and class 6 (FD > 300 μm). Folliculogenesis commenced in intrauterine life and was completed by day 10 after birth in this species. Class 1 follicles were present on day 0, whereas follicles of classes 2, 3, 4, and 5 and 6 appeared on days 10, 12, 13, and 20 after birth, respectively. The regression equations relating the growth of the oocyte to the growth of follicles exhibited a biphasic pattern as reported for other mammals. A positive linear relationship was noted between the total number of large follicles (classes 2–6) and the total number of small follicles (class 1), and between the numbers of healthy follicles and atretic follicles. The observed decrease in the total number of large follicles (classes 2–6) in the ovary in relation to age was found to be mainly due to reduction in the population of class 2 follicles. The presence of a greater number of oocytes at the time of birth and the subsequent presence of a greater number of follicles of classes 2–4 in the left ovary than in the right ovary of the musk shrew in all age groups suggests ovarian asymmetry in follicular distribution in this polyovular species.
Revision of Haliotrema species (Monogenea: Ancyrocephalidae) from Atlantic boxfishes (Tetraodontiformes: Ostraciinae): morphology, morphometrics, and distribution
Authors: Klassen Greg
Published: February 2008

Six species of Haliotrema, H. lactophrys, H. guadeloupensis, H. glandulosum, H. torridum, H. minutum, and H. kritskyi, found on the gills of seven species of Atlantic boxfishes (Ostraciinae) of the genera Acanthostracion and Lactophrys are redescribed. These species are found to be more similar to Haliotrema species on perciform hosts (i.e., Chaetodontidae, Labridae, and Mullidae) from the Caribbean than to congeners on other tetraodontiform hosts. In addition to clear morphological distinction, the results of a canonical discriminant analysis on 30 morphometric variables indicated that these variables also contribute, as a correlated group, to species distinction (p = 0.0001). The synergistic relation among the variables was identified as a shape component associated most strongly with the dorsal and ventral hamuli. The distributions of these parasite species indicated that none is specific to any one host species; specificity was more pronounced at the host genus level. Patterns of parasite distribution on host populations indicated a complicated distribution history.
The costs of reproduction in tree swallows (Tachycineta bicolor)
Authors: Wheelwright Nathaniel T. , Leary Joanna , Fitzgerald Caragh
Published: February 2008

We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.
Distribution of gizzard nematodes (Habronematoidea, Acuarioidea) of New World shorebirds (Charadriiformes), with special reference to localities of transmission
Authors: Wong P. L. , Anderson R. C.
Published: February 2008

Eleven species of gizzard nematodes were found in 27 of 41 (66%) species of the Charadriidae, Haematopodidae, Recurvirostridae, and Scolopacidae. They were found mainly in large shorebirds, possibly because they use large crustaceans (e.g., decapods) as intermediate hosts. The presence of identifiable larvae indicated that five species are transmitted in marine environments: (1) Stellocaronema skrjabini, found in 15 shorebird species, is transmitted on the Pacific and Gulf coasts of the United States and Peru; (2) Schistorophus skrjabini, found in three shorebird species, is transmitted on the Pacific and Gulf coasts of the United States; (3) Sciadiocara umbellifera, found in nine shorebird species, is transmitted along the coasts of Texas and Peru; (4) Viktorocara capillaris, found in six shorebird species, is transmitted on the Pacific and Gulf coasts of the United States; (5) Viktorocara limosae, found in 13 shorebird species, is transmitted on the Pacific coast of the United States. Acuaria sp. was found in two long-billed curlews (Numenius americanus) breeding in Alberta and one sanderling (Calidris alba) wintering in Peru. Streptocara sp. was found in four shorebird species, and the presence of larvae in a willet (Catoptrophorus semipalmatus) indicated that transmission takes place in Alberta. Chevreuxia americana, found in six shorebird species, was most common in American avocets (Recurvirostra americana) and black-bellied plovers (Pluvialis squatarola). Sciadiocara bihamata was found in four shorebird species but was most common in black-bellied plovers. Sciadiocara cucullatus was found in one long-billed curlew collected in Texas. Sobolevicephalus lichtenfelsi was found in marbled godwits (Limosa fedoa) and willets.
Influence of resource distribution and abundance on home-range characteristics of southern flying squirrels
Authors: Fridell R. A. , Litvaitis J. A.
Published: February 2008

We compared the distribution and abundance of a major food resource (mast-producing trees) and potential den sites (snags) with the composition and size of summer home ranges of eight (four male, four female) southern flying squirrels (Glaucomys volans). Large hickories (Carya ovata) (> 16 cm diameter at breast height) and beeches (Fagus grandifolia) were more abundant in intensively used portions of squirrel home ranges than in random sites. Home ranges of male squirrels also contained greater densities of large red oaks (Quercus borealis) and large white oaks (Quercus alba) than did home ranges of females. Female flying squirrels occupied home ranges with a greater abundance of snags than did males. We suggest that females moved into areas with an abundance of potential dens and relatively low food resources while rearing young in response to competition for maternal dens, or to avoid contact with other squirrels. Home ranges of males were larger than those of females. Estimated home ranges in our study area (at the northern edge of the distribution of southern flying squirrels) were 1.5–20 times larger than estimates from regions to the south. Locally, home-range size was not correlated with the abundance of mast-producing trees. However, if viewed on a biogeographic scale, home-range size may be influenced by the abundance of mast-producing trees.
Dispersion of introduced arctic hares (Lepus arcticus) on islands off Newfoundland's south coast
Authors: Small Robert J. , Keith Lloyd B. , Barta Robert M.
Published: February 2008

We describe dispersion of radio-collared arctic hares (Lepus arcticus) introduced to three islands off Newfoundland's south coast. Nearest-neighbor analyses indicated that home-range activity centers were aggregated during both summer and winter. Mean distances between activity centers were significantly less during winter than during summer, with the greatest aggregation observed when rates of fox predation were least and snow depth and persistence were greatest. Arctic hares apparently lack a rigid social-dominance system; hence, environmental factors such as availability of food sources, snow conditions, and presence of predators may primarily influence dispersion.
Repeatability of size and shape of American Pipit eggs
Authors: Hendricks Paul
Published: February 2008

Variation in size and shape of American Pipit (Anthus rubescens) eggs was studied from 1987 to 1989 at two sites in the Beartooth Mountains, Park County, Wyoming. Differences in four egg traits were detected within clutches among females for all years and at both sites; there were differences between years and sites as well. Coefficients of variation for clutch means ranged from 1.52 (breadth) to 5.02 (volume). Mean repeatability estimates (± SD) of four independent samples were 0.75 ± 0.05, 0.64 ± 0.08, 0.70 ± 0.10, and 0.70 ± 0.08 for length, breadth, volume, and elongation, respectively, suggesting a significant heritable component in the phenotypic variation of egg size and shape. The difference between mean length and breadth repeatabilities was significant (P < 0.02). Repeatabilities of volume were the most variable of all traits and varied between years by as much as 22%, and between sites in 1989 by as much as 19%. Site differences are probably due to local environmental effects, and not a result of differences in the underlying genotypic variance. Repeatability estimates for American Pipit eggs were similar to those for a variety of bird species breeding in very different habitats. However, repeatability estimates can be calculated several ways and caution should be used when comparing estimates until it can be shown that these estimates are comparable for the same population.