bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersal gradients of conidia of the butternut canker fungus in a forest during rain
Authors: Tisserat N. , Kuntz J. E.
Published: April 2008

Dispersal gradients of conidia of Sirococcusclavigignenti-juglandacearum Nair, Kostichka, and Kuntz, the causal agent of butternut canker, were studied in the forest for various rainfall dates. During rain, large numbers of conidia from branch cankers were carried in runoff water down the tree trunks of butternut (Juglanscinerea L.), causing infections that resulted in trunk cankers. Conidia also were dispersed in small droplets or aerosols and disseminated up to 40 m from a cankered tree during rainfall. Concentrations of conidia in the air decreased exponentially with increasing distances from the inoculum source. Dispersal gradients were influenced by stand composition and (or) size of the inoculum source, with steeper gradients associated with a dense forest canopy and a small area source of inoculum. Weather conditions, excluding the necessity for rain, had little influence in altering dispersal gradients within the same stand for different rainfall dates.
Soils and foliar nutrient analysis of Chamaecyparislawsoniana and Thujaplicata in southwestern Oregon
Authors: Imper David K. , Zobel Donald B.
Published: April 2008

Surface mineral soil and foliage associated with Chamaecyparislawsoniana (A. Murr.) Parl. and Thujaplicata Donn ex D. Don were sampled at six sites in southwestern Oregon. Total soil nitrogen concentrations ranged from 0.08 to 0.37%. Percentage exchangeable concentrations of other soil nutrients were 0.0002–0.0020 P, 0.014–0.224 Ca, 0.002–0.018 K, and 0.002–0.023 Mg. Foliage of Chamaecyparis contained 0.9–1.9% N, 0.11–0.23% P, 0.8–1.9% Ca, 0.67–1.20% K, and 0.11–0.26% Mg. Foliage of Thuja contained 0.9–1.6% N, 0.12–0.24% P, 1.1–2.0% Ca, 0.52–0.95% K, and 0.06–0.23% Mg. Overall, foliage of Chamaecyparis contained significantly higher concentrations of K, and tended to have lower Ca:Mg ratios than that of Thuja. Concentrations of soil nutrients showed no obvious relation to species occurrence on a study-wide basis. Within sites where the two species grew together, however, Thuja was associated with higher soil Ca:Mg ratios and foliar Ca, and Chamaecyparis was associated with higher levels of soil K and foliar N. Foliar nutrient concentrations showed little relation to concentrations in soil, although low soil Ca, P, and Mg concentrations were reflected in foliage at some sites. Soils in the study area have higher Ca:Mg ratios and more available N than soils over much of Chamaecyparis' range. Given the apparent nutritional requirements of Thuja, it seems unlikely that it will significantly replace Chamaecyparis killed by root rot.
Effects of chilling and photoperiod on dormancy release of container-grown loblolly pine seedlings
Authors: Garber Melvin P.
Published: April 2008

Loblolly pine (Pinustaeda L.) seedlings, which set bud in fall, required exposure to chilling temperatures before growth could resume under a 10- or 12-h photoperiod; whereas a 14-h photoperiod partially substituted for the chilling requirement. A 10- to 14-h photoperiod, however, did not affect the rate of budbreak once the chilling requirement was satisfied. A broad temperature range (0 – 12 °C) was equally effective in satisfying the chilling requirement. In situations where subfreezing temperatures were sufficient to decrease the extent of shoot growth or result in seedling mortality, the rate of budbreak for surviving seedlings was not affected. Exposure to low but above freezing temperatures beyond that necessary to satisfy the chilling requirement for budbreak resulted in increased height growth. Chilling temperatures apparently were involved both in ameliorating bud dormancy and promoting vegetative growth.
Goal programming formulations and extensions: an overview and analysis
Authors: Mendoza Guillermo A.
Published: April 2008

This paper provides an overview and expository analysis of goal programming (GP) formulations and extentions. The paper surveys both the traditional and recent GP methodologies. Moreover, it also discusses some of the issues, implications, and criticisms about the technique, such as (i) use of preemptive priorities, (ii) use of weights or scaling factors among noncommensurable goals, (iii) nondominance in GP solutions, (iv) efficient target levels, (v) alternative optima and unbounded solutions, and (vi) GP as a satisficing or optimizing technique.
Tree species distributions related to climatic patterns in Michigan
Authors: Denton Shirley R. , Barnes Burton V.
Published: April 2008

Relationships between the distributions of major forest species and climatic patterns in Michigan were examined using binary discriminant analysis ordination, Kolmogrov–Smirnov statistics, histograms, and correlation coefficients. Species occurring only in southern Lower Michigan (e.g., sassafras, Sassafrasalbidum (Nutt.) Nees) were strongly associated with warm, long growing seasons that had high night temperatures, low precipitation relative to potential evapotranspiration throughout the summer months, and low heat sums prior to last spring freeze. Species found throughout Lower Michigan but not extending into Upper Michigan (e.g., black oak, Quercusvelutina Lamarck, and white oak, Q. alba L.) had similar associations except that they were not strongly associated with low heat sums prior to last spring freeze. Conifers (e.g., balsam fir, Abiesbalsamea (L.) Miller, and white pine, Pinusstrobus L.) were associated with short growing seasons of highly variable length, high heat sums prior to last spring freeze, high precipitation relative to potential evapotranspiration even in July and August when the difference between precipitation and evapotranspiration was greatest, and low night temperatures relative to daytime temperatures. All species had individualistic correlations with major climatic statistics. Species range limits, where they occurred in the state, were generally simultaneously correlated with more than one climatic variable.
Allometric relations of deciduous (Larixoccidentalis) and evergreen conifers (Pinuscontorta and Pseudotsugamenziesii) of the Cascade Mountains in central Washington
Authors: Gower Stith T. , Grier Charles C. , Vogt Daniel J. , Vogt Kristiina A.
Published: April 2008

Logarithmic equations for estimating component biomass and projected leaf area from stem diameter and (or) sapwood cross-sectional area were computed for western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in a mixed conifer stand in the Cascades of central Washington. Regression equations for estimating foliage biomass reported in this study did not compare favorably with foliage biomass allometric relations from other studies. For a given diameter, western larch supported a greater current foliage mass than lodgepole pine or Douglas-fir (P < 0.001); however, the total foliage mass of lodgepole pine was significantly greater (P < 0.001) than western larch. Despite lodgepole pine supporting a total foliage mass approximately twofold greater than western larch, allometric relations between foliage area and stem diameter were not different (P > 0.05) between the deciduous and evergreen conifer. Western larch supports a needle morphology that provides a greater photosynthetic surface area per unit of carbon invested than evergreen conifers in this environment.
Fuel succession in a western hemlock/Douglas-fir forest
Authors: Agee James K. , Huff Mark H.
Published: April 2008

Fuel succession was quantified for a 515-year chronosequence in a Tsugaheterophylla/Pseudotsugamenziesii forest. Postfire stand ages selected were 1, 3, 19, 110, 181, and 515. After initial reductions due to mortality from fire in the first 3 years, live aboveground biomass in the tree component increased over time to over 1100 t/ha. Shrub and herb layer biomass was highest in year 19 and year 515. Dead aboveground biomass had different trends for different fuel size classes; normalized fuel loadings of five dead and down fuel categories peaked at four different stand ages: 1-h and 10-h timelag (TL) fuels, age 1; 100-h TL fuels, age 19; 1000-h TL fuels, age 110; >1000-h TL fuels, age 515. Surface fire behavior was highest early in the sere and lowest at ages 110–181. Old-growth forest patches appear to be best buffered against forest fire by mature forest patches rather than old growth or recently burned natural stands.
An index to fire incidence
Authors: Quinby P. A.
Published: April 2008

To support the development and use of an index to fire incidence, historical data from modern fire records and forest resource inventory maps were used to test the null hypothesis that fire incidence within pine, intolerant hardwood, and tolerant hardwood forests does not differ significantly. The null hypothesis was tested with (i) the χ2 test of goodness of fit applied to species dominance type data within burned plots and randomly chosen plots and (ii) a t-test to identify significant fire incidence differences among the 10 overstory species and the three forest types. The first test showed a significant difference between expected and observed results. The second test showed that, although not significantly different themselves, the pine and intolerant hardwood forest types had a significantly higher fire incidence than the tolerant hardwood type. Although no one overstory species had a fire incidence significantly different from all others, each species differed significantly from at least two others. Because both post- and pre-fire data were used, it was impossible to distinguish vegetation flammability from species regeneration strategy as an explanation for fire incidence as measured. However, since crown fire is a rare event in the temperate forests of eastern North America, it is likely that most postfire vegetation samples represented the vegetation that was present at ignition. Thus, it is also likely that the majority of data indicate species flammability rather than species regeneration strategy. Finally, a method for calculating the index to fire incidence is presented.
Phenyl indole-3-thiolobutyrate increases growth of transplanted 1-0 red oak
Authors: Struve Daniel K. , Rhodus W. Timothy
Published: April 2008

The basal 1 cm of taproot of dormant bareroot 1-0 red oak (Quercusrubra L.) seedlings were given a 3-s dip in 20, 40, or 80 mM concentrations of indole-3-butyric acid (IBA), phenyl indole-3-thiolobutyrate (P-ITB), or equal parts IBA and P-ITB at 20 or 40 mM concentrations. Sixty control seedlings were dipped in 95% ethanol, while 30 seedlings were used for each auxin treatment. Seedlings were potted on May 12, 1986, and grown outdoors. At the end of the 104-day study period, all concentrations of IBA and P-ITB significantly increased number of roots regenerated (from 5.3 with 20 mM IBA to 11.9 for 80 mM IBA) compared with control seedlings. However, P-ITB-treated seedlings produced significantly more leaves (20–24) and leaf area (320–472 cm2), and up to 10 g more dry weight than IBA and non-auxin-treated seedlings. P-ITB treated seedlings had higher relative growth and net assimilation rates and lower leaf area ratio than IBA-treated or control seedlings. Seedlings treated with 20 mM of equal parts IBA and P-ITB were similar to P-ITB-treated seedlings while seedlings treated with the 40 mM IBA and P-ITB combination were similar to IBA-treated seedlings.
A comparative study of shoot and root development of interior and coastal Douglas-fir seedlings
Authors: Fielder Peter , Owens John N.
Published: April 2008

Bud development and root elongation of coastal and interior seedlots of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were compared from September through March after 4 months of growth under Styroblock container nursery production conditions. Apical development of vegetative buds was described in terms of morphology, mitotic index, apical dimensions, and cell numbers. An estimate was made of the number of leaf primordia produced on the embryonic shoot. Morphological and anatomical stages of bud development in the interior variety occurred about 4 weeks in advance of those in the coastal variety. Cell divisions ceased in apices in November and December in interior and coastal varieties, respectively, and resumed in mid-February in both varieties, so all apices were undergoing cell division by March 1. Flushing was variable but occurred earlier in the interior variety. Numbers of white root tips were highest during October and March in both varieties. Root elongation tended to follow the pattern of bud development in each variety, so the interior variety had greater numbers of white root tips >0.5 mm long about 2 weeks earlier in the fall than the coastal variety. Apical activity and peak numbers of root tips >0.5 mm long were synchronized in both varieties by the following March. In the interior variety white root tips were absent during December and January whereas some were present throughout the sampling period in the coastal variety. The interior variety produced a larger bud and entered dormancy earlier than the coastal variety when cultivated under coastal conditions. Differences in phenology between the two varieties are sufficient to justify the development of more specific nursery cultural practices to achieve maximum seedling quality.
Effect of partial cutting treatments of lodgepole pine stands on the abundance and behavior of flying mountain pine beetles
Authors: Schmitz Richard F. , McGregor Mark D. , Amman Gene D. , Oakes Robert D.
Published: April 2008

Passive barrier traps deployed at three heights above ground were used to determine the effect of five intensities of partial cutting of lodgepole pine (Pinuscontorta Dougl. ex Loud. var. latifolia Engelm.) and two unthinned check stands on response of flying mountain pine beetles (Dendroctonusponderosae Hopkins) from 1980 to 1983 on two sites in western Montana. Percentages of mountain pine beetles caught 4 years after thinning were significantly greater in the least severely thinned (27.6 m2 basal area/ha) treatment (27%) and the unthinned check (28%) than in the 25.4 cm diameter limit (8%) and the 23.0 m2 basal area/ha (7%) thinnings (P < 0.05). Numbers of mountain pine beetles trapped in the 18.4 m2 basal area/ha thinning did not differ significantly from other treatments. The proportions of mountain pine beetles caught at three trapping heights differed significantly (P < 0.05), totaling 63, 28, and 9% at midbole, midcrown, and 1.8 m above ground, respectively. Fewer trees were killed in relation to the numbers of mountain pine beetles trapped in the most severely thinned stands. However, tree mortality rates could not be attributed to thinning-induced changes in tree vigor. These findings, and the preference of flying mountain pine beetles for the midbole stratum, suggest that stand environment is an important factor regulating the severity of tree killing.
The B chromosomes of Claytoniacaroliniana (Portulacaceae) and maple forest dieback
Authors: Gervais C. , Roy G. , Grandtner M. M. , Désaulniers G.
Published: April 2008

Claytoniacaroliniana (Michx.) is a perennial early-flowering species regularly occurring in northeastern American maple forests and frequently possessing accessory (B) chromosomes. A cytological study of Claytonia populations growing in eight maple stands diversely affected by dieback has shown important variations in their B chromosome levels. The severity of dieback was negatively correlated with the presence of the B chromosomes, the observed data being adequately adjusted (R = 0.957 and 0.947) to the values estimated from the explicative variables. Different hypotheses are considered to explain the phenomenon: coincidence with a preexisting situation related to marginal habitats; ecological changes in dieback-damaged zones; or the present influence of stresses affecting both B chromosomes of Claytonia and maple trees by divergent or anologous processes.
Shoot, needle, and cambial growth phenology and branch tracheid dimensions in provenances of lodgepole pine
Authors: O'Reilly Conor , Owens John N.
Published: April 2008

Shoot and needle growth phenology was studied in first-order fourth-whorl branches from seven provenances of Pinuscontorta Dougl. ssp. latifolia Engelm. from British Columbia and the Yukon, growing in a provenance trial at Prince George, British Columbia. The phenology of tracheid production was followed in cross sections from the midportion of the 1st-year increment of similar branches. Tracheid diameter and wall thickness were measured at increments across the ring in sections from dormant branches. Differences among provenances in the dates of growth initiation were small or negligible, although early relative growth rates were higher in the northern provenances. The times of cessation differed greatly among provenances for needle and cambial growth, but less for shoot elongation. Duration of growth had the largest effect on final needle length and tracheid numbers. Shoot length was affected largely by rates of elongation. The northern provenances had few, narrow-diameter, relatively thin-walled tracheids. Provenances showed contrasting patterns in diameter measurements across the ring, but wall thickness displayed a more consistent trend.
Prediction of long-term growth rates of larch clones by calorimetric measurement of metabolic heat rates
Authors: Hansen L. D. , Lewis E. A. , Eatough D. J. , Fowler D. P. , Criddle R. S.
Published: April 2008

A linear correlation exists between long-term growth rates and calorimetrically measured metabolic heat rates in some clones of larch (Larixlaricina (Du Roi) K. Koch). The metabolic heat rate per gram of tissue was found to be highly variable among clones from different trees and reproducible for clones of the same tree. The ordering of metabolic rates for clones was shown to be independent of the physiological growth stage in which the measurements were made. Winter-hardened tissue was found to be immediately active on warming to room temperature.
Inoculation of lodgepole pine with four blue-stain fungi associated with mountain pine beetle, monitored by a heat pulse velocity (HPV) instrument
Authors: Yamaoka Y. , Swanson R. H. , Hiratsuka Y.
Published: April 2008

In two separate experiments in the field, healthy 80-year-old lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) were inoculated with four blue-stain fungi that are associated with mountain pine beetle (Dendroctonusponderosae Hopk.) and beetle-attacked trees. Inocula of Ophiostomaclavigerum (Robins.-Jeff. & Davids.) Harrington, O, huntii (Robins.-Jeff.) de Hoog & Scheffer, O. montium (Rumb.) von Arx, and O. minus (Hedge.) H. & P. Sydow were prepared on sawdust media. Inoculum was placed under the bark in two areas (8 × 5 cm each), one above the other, separated by a 15-cm space in which heat pulse velocity (HPV) sensors were installed. HPVs in the inoculated trees were monitored daily for 4 weeks. In sections inoculated with O. clavigerum, HPVs were significantly reduced 10 to 13 days after inoculation in both experiments. Sapwood under the inoculated area was visibly altered and colonized by the fungus. The other three fungi did not significantly reduce HPVs. These results proved the capability of O. clavigerum to colonize functional sapwood and stop sap flow within a short period of time and reconfirmed the importance of this fungus in the mortality of trees attacked by mountain pine beetle.
Comparisons of yellow cypress trees of seedling and rooted cutting origins after 9 and 11 years in the field
Authors: Karlsson Ingemar , Russell John
Published: April 2008

Trees of rooted cutting and seedling origins of yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) were compared for survival and growth in two field experiments at 9 and 11 years after establishment. Experiment 1 evaluated seedlings and rooted cuttings from 1-, 3-, and 7-year-old donors. Experiment 2 compared rooted cuttings from 2-year-old donors and seedlings from the same 10 open-pollinated families. Survival was high in both experiments, with no significant differences between propagule types. In experiment 1, trees of rooted cutting origin from 1-year-old donors were significantly taller than trees of rooted cutting origin from 3- and 7-year-old donors, but there was no significant difference between trees of seedling and rooted cutting origin from any of the donor age groups. Experiment 2 found no significant differences between trees of rooted cutting and seedling origin in height or diameter, and no significant differences between families. However, in this experiment, rooted cuttings had significantly fewer multiple tops than seedlings. It is concluded that the use of rooted cuttings is a viable alternative to seedlings in reforestation of yellow cypress.
Effects of ozone and acidic fog on red spruce needle epicuticular wax ultrastructure
Authors: Percy K. E. , Krause C. R. , Jensen K. F.
Published: April 2008

The effect of ozone and acidic fog on the epicuticular wax structure of elongating red spruce (Picearubens Sarg.) was examined. Needle exposure to 70 and 250 ppb ozone for 11 weeks resulted in a coalescence of crystalline tube ends within epistomatal chambers. Exposure to acid fog at pH 3.0 resulted in the formation of amorphous wax deposits over the existing tubes within the epistomatal chambers. New structures consisting of upright, irregular wax plates were observed in nonstomatal areas on needles exposed to pH 3.0 fog. These findings indicate that ozone and acid fog applied at near ambient doses can alter epicuticular wax ultrastructure on elongating red spruce needles. Ultrastructural changes induced by ozone and acid fog resulted from a direct pollutant interaction with wax crystallization and wax biosynthesis, respectively, and were not due to erosion or weathering of needle surfaces.
Variation in N, P, and K status and N efficiency in some North American willows
Authors: Simon M. , Zsuffa L. , Burgess D.
Published: April 2008

Differences in N, P, and K status and N efficiency of some North American willow species and their clones were observed and evaluated. Salixeriocephala Michx., S. lucida Mühl., and S. exigua Nutt., represented by five clones each, were raised from cuttings in potted loamy sand for 113 days. Plants were subjected to three levels of fertilization (equivalent to 125, 250, or 500 kg N/ha) applied at exponential rates of addition (0.06, 0.071, and 0.082, respectively), using complete nutrient solutions and were compared with control plants (no fertilizer added). The experiment showed that nutrient concentration and nutrient uptake in the plants depended not only on treatments but also on species and clones. Thus, species and clones that removed smaller amounts of nutrients per unit of biomass could be selected. Species had a larger effect than clones on nutrient concentration and content. Total nutrient content, at the same treatment level, depended primarily on biomass production. Significant variation existed among species and clones in the ratio of biomass/total N. Salixeriocephala (the best species) produced 35.1% more than the other species, and the best experimental clones within species produced 27.8–41.6% more stem per unit of N than the poorest clones.
Jack pine establishment on ash from wood and organic soil
Authors: Thomas P. A. , Wein Ross W.
Published: April 2008

Wildfires after prolonged drought consume quantities of fallen trees and soil organic layers. We hypothesized that conflicts within the literature about establishment success of conifers on the resulting ash were a result of the different types of ash used (from wood or peat) and degree of leaching. This was tested using jack pine (Pinusbanksiana Lamb.) in field and laboratory experiments. Ash from peat was chemically neither detrimental nor advantageous to jack pine establishment. No seedlings survived on unleached wood ash. Leaching improved germination and survival, but leached aspen ash was usually a poorer substrate than leached ashes from conifers. There was no consistent differences between ash from different conifers nor degree of decomposition prior to burning. Chemical analysis of the wood ash suggested the high pH of 10.6–12.5 caused by high hydroxide and bicarbonate levels to be directly harmful.
de Liocourt's law and the truncated law
Authors: Chevrou R. B.
Published: April 2008

New estimates are proposed for de Liocourt's law parameter q (the q-ratio) and for the number of trees in each diameter class, which depends only on the average diameter of the tallied trees. A new empirical diameter distribution that fits real tree numbers and tree volumes in the diameter classes better than de Liocourt's law does for both even-aged and uneven-aged stands is then presented. It is named the truncated law, because the age of the trees is truncated on the right by a maximum value. It depends on two parameters, α and β, α being related to the average annual thinning rate and β being related to the maximum age of the trees and the average diameter of the oldest trees. It is shown that the average diameter of the tallied trees, as well as the q-ratio, depends on the thinning rate, on the maximum age of the trees, on the average diameter growth for a specific set of environmental conditions, and on silviculture. de Liocourt's law is a special case of the truncated law.
Genetic relationships of meadow vole (Microtus pennsylvanicus) populations in central Appalachian wetlands
Authors: Francl K. E. , Glenn T. C. , Castleberry S. B. , Ford W. M.
Published: April 2008

We sequenced and compared variation within a 375-base-pair segment of the mitochondrial DNA control region of 323 meadow voles ( Microtus pennsylvanicus (Ord, 1815)) among 14 populations to determine the influence of past and present landscape connectivity among isolated wetlands in the central Appalachian Mountains. To best explain observed differences among sites, we used genetic and landscape-level (GIS) data to test a null hypothesis (no genetic differences) and three alternate explanations of significant variation owing to founder effects, effective population size, or isolation by distance. Sequencing results revealed 16 distinct haplotypes (1–8 haplotypes/site), with two present in samples from most wetlands, and half of the remaining haplotypes concentrated in specific geographic clusters. Our findings best support the explanation that founder effects have influenced current genetic patterns among sites. These founder effects are likely due to historical land-use activities such as exploitative logging (ca. 1880–1920; creating early successional habitats for voles) and subsequent forest regeneration over the past half century; they were also likely influenced by postglacial colonization patterns. Therefore, current genetic diversity in these populations seems to largely reflect the number and source of voles that successfully colonized these isolated wetlands during the window of opportunity immediately following extensive logging.
Differential responses of marsh predators to rainfall-induced habitat loss and subsequent variations in prey availability
Authors: Canepuccia A. D. , Farias A. A. , Escalante A. H. , Iribarne O. , Novaro A. , Isacch J. P.
Published: April 2008

Rainfall has increased in many regions during recent decades, but most information is from dryland ecosystems, which precludes generalizations about its ecological consequences. We explored the effects of increased flooding on the Geoffroy’s cat, Leopardus geoffroyi (d’Orbigny and Gervais, 1844), and pampas fox, Pseudalopex gymnocercus (G. Fischer, 1814), exposed to an abnormally rainy period in marshes at Mar Chiquita, Argentina. In particular, we assessed the effects of flooding on (i) habitat use by L. geoffroyi and P. gymnocercus, (ii) abundance of their main prey, and (iii) functional responses of predators to variations in prey abundance. Overall, simple regression analysis identified negative effects of flooding on abundance of prey (rodents, waterbirds, and arthropods), but structural-equation modeling and logistic generalized linear models identified differential effects of rainfall on habitat use by and functional responses of predators, respectively. Habitat use by L. geoffroyi was more negatively affected by interannual variability in flooding-induced habitat loss, particularly through its effect on waterbirds. At the same time, habitat use by P. gymnocercus was less affected, likely because this species was less dependent on prey from flooded areas and used higher elevation habitats. Given that most native grasslands in elevated areas have been converted to agriculture, the more specialized L. geoffroyi faces a greater threat if current trends of climate change persist in this region.
Potential of habitat complexity for mitigating interference competition between native and non-native salmonid species
Authors: Hasegawa Koh , Maekawa Koji
Published: April 2008

This study aimed to confirm the mitigation effect of structurally complex habitat on interspecific interference competition between native and non-native salmonid species. We evaluated the effects of habitat complexity (number and size of aggregates of large woody debris and length of undercut banks) and other habitat components that were related to the local abundance of salmonids (dimension and mean depth of pool, mean particle size, and mean current velocity) on the local abundance of native white-spotted char ( Salvelinus leucomaenis (Pallas, 1814)) in allopatry and sympatry with non-native brown trout ( Salmo trutta L., 1758). The field survey was conducted in a Japanese montane stream. The number of char in pool habitats in the allopatric area correlated positively with habitat size, i.e., pool dimension. The number of char in the sympatric area with trout was positively correlated with habitat complexity, while it was negatively correlated with number of trout. In this study, we found that structurally complex habitats might be effective in mitigating interspecific competition between native white-spotted char and non-native brown trout in a montane stream.
Early survival of Punjab urial
Authors: Awan Ghulam Ali , Festa-Bianchet Marco , Gaillard Jean-Michel
Published: April 2008

There is almost no information on age-specific survival of Asiatic ungulates based on mark–recapture studies. Survival of marked Punjab urial ( Ovis vignei punjabiensis Lydekker, 1913) aged 0–2 years was studied in the Salt Range, Pakistan, in 2001–2005. Male lambs were heavier than females at birth. The relationship between litter size and birth mass varied among years, with a tendency for twins to be lighter than singletons. Birth mass had a positive but nonsignificant relation with survival to 1 year. Neither sex nor litter size affected survival to 1 year, which averaged 55% (95% CI = 41%–68%). There was no sex effect on survival of yearlings, which averaged 88% (95% CI = 4%–100%). Although survival of lambs and yearlings was similar to that reported for other ungulates, apparent survival of 2- and 3-year-olds was very low at only 47%, possibly because of emigration. Early survival in this protected area is adequate to allow population growth, but more data are required on adult survival.
Recent porcupine expansion at tree line: a dendroecological analysis
Authors: Payette Serge
Published: April 2008

The northernmost porcupine (Erethizon dorsatum L.) populations in the western part of northern Quebec are found at tree line along the Hudson Bay coast. A dendrochronological analysis of feeding scars produced during the dormant period indicates that this species expanded significantly during the 20th century, particularly during the last 25 years. Confined to small, marginal forest sites during the 19th century, porcupine range increased afterwards and climaxed during the 1960's and 1970's with the occupance of remote altitudinal tundra sites. This change in porcupine range coincides with the area where white spruce (Picea glauca (Moench) Voss) expanded during the last 100 years because of climatic warming. It is hypothesized that porcupine populations responded to climate change with a time lag of several decades associated with forest-niche building.
Estimation of snowshoe hare population density from turd transects
Authors: Krebs Charles J. , Gilbert B. Scott , Boutin S. , Boonstra R.
Published: April 2008

We counted the number of snowshoe hare (Lepus americanus) fecal pellets on 50 quadrats of 0.155 m2 on each of six areas near Kluane Lake, Yukon Territory, once a year from 1977 to 1983. On four of these areas we livetrapped hares once a month and estimated population density from the Jolly–Seber model. Average hare density for the year was linearly related to fecal pellet counts (r = 0.94) over the range 0–10 hares/ha. Mean turd counts also are related to the variance of these counts by Taylor's power law with exponent 1.30, indicating a clumped pattern in turd deposition. Fecal pellet counts provide a quick and accurate method for snowshoe hare censuses on an extensive scale.
Enzymes of energy metabolism in salmonid hearts: spongy versus cortical myocardia
Authors: Ewart H. Stephen , Driedzic William R.
Published: April 2008

The maximal in vitro activity of key enzymes of energy metabolism from the spongy and cortical layers of adult Atlantic salmon (Salmo salar) hearts was determined. Enzymes were also measured in hearts from salmon parr and smolt, and from juvenile and adult trout (Salvelinus fontinalis). Indices of carbohydrate metabolism, hexokinase, and lactate dehydrogenase were significantly higher in the spongy than in the cortical layer of the salmon heart. Markers of aerobically based fatty acid metabolism (carnitine palmitoyl transferase, β-hydroxyacyl CoA dehydrogenase, and cytochrome oxidase) were higher in the cortical region. Although there were clear differences in metabolic organization between the two tissue layers, the absolute magnitude of the enzyme activities suggest that the large variance in oxygen delivery to the two regions does not present a major constraint on aerobic energy metabolism. In both salmon and trout, the hearts from large animals exhibited much higher enzyme activities at many loci than the hearts from small animals. The data imply that there is an increase in metabolic fuel supply on a per gram weight basis in large hearts. This is contrary to the accepted paradigm of scaling of aerobic metabolism. Myoglobin content was highly variable amongst experimental groups. High levels of myoglobin were associated with potential conditions of low extracellular oxygen availability.
Genetic basis of sterility in hybrid males from crosses of Glossina morsitans morsitans and Glossina morsitans centralis (Diptera: Glossinidae)
Authors: Gooding R. H.
Published: April 2008

Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado carrying from one to three marker genes on each chromosome were hybridized. F1 females were backcrossed and the resulting backcross males were tested for their ability to inseminate and to fertilize both G. m. morsitans and G. m. centralis; these abilities were then related to the genetic constitution of each male. Hybrid males having an X chromosome from one subspecies and a Y chromosome from the other were sterile, as were about half the males having X and Y chromosomes from the same subspecies. There is weak evidence for autosomal involvement in hybrid sterility but this involvement is not through genetical recombination between the loci Ao and Xo, nor does it depend upon the number of autosomes from the same taxon as the sex chromosomes. Hybrid males descending from G. m. morsitans females could not fertilize G. m. centralis although they could inseminate them. F1 hybrid females had lower than expected intrachromosomal recombination in the X chromosome and in linkage group II, and hybrid females tended to use autosomes of G. m. centralis origin more frequently than chromosomes from G. m. morsitans. Models for evolution of the maternally inherited sterility factor(s) suggest that G. m. centralis is ancestral to G. m. morsitans. Use of hybrid males descending from female G. m. morsitans for genetic control of G. m. centralis is proposed.
Sexual dimorphism in the cranial development of Scandinavian moose (Alces alces (L.) alces)
Authors: Bartosiewicz László
Published: April 2008

Sex-dependent developmental changes in eight cranial measurements were studied using a stepwise discriminant analysis and allometric equations on 99 Scandinavian moose (Alces alces (L.) alces) skulls to define gross sex-related tendencies. While a considerable overlap between sexes is apparent when only univariate statistics are compared, allometric equations show differences between sexes in terms of relative growth intensities. All measurements studied display more intensive growth in males when compared with basal length. In the facial portion of the skull, however, the relative increase of palatal length is particularly rapid, while growth of the premolar row is especially slow in females. Other signs of secondary sexual dimorphism appear in neurocranium measurements and are apparently related to the seasonal presence of antlers in bulls.
Supercooling ability of aphid populations from British Columbia and the Canadian Arctic
Authors: O'Doherty Rose , Ring Richard A.
Published: April 2008

Adults and first-instar nymphs of the peach–potato aphid Myzus persicae of Canadian origin maintained under favourable laboratory conditions were capable of extensive supercooling potential, to below −20 °C, as were summer morphs which were field collected in British Columbia. Adult Aphis epilobii collected in summer from the Arctic also possessed considerable supercooling capacity. The data are comparable with those gathered in other aphid cold hardiness studies and suggest that a general pattern of supercooling potential may exist in aphid species and may be independent of geographical or habitat origins.
THE IMPACT OF MEDIA COVERAGE ON THE DYNAMICS OF INFECTIOUS DISEASE
Authors: LIU YIPING , CUI JING-AN
Published: April 2008

In this paper, we give a compartment model to discuss the influence of media coverage to the spreading and controlling of infectious disease in a given region. The model exhibits two equilibria: a disease-free and a unique endemic equilibrium. Stability analysis of the models shows that the disease-free equilibrium is globally asymptotically stable if the reproduction number (ℝ0), which depends on parameters, is less than unity. But if ℝ0 > 1, it is shown that a unique endemic equilibrium appears, which is asymptotically stable. On a special case, the endemic equilibrium is globally stable. We discuss the role of media coverage on the spreading based on the theory results.
AN IMPULSIVE PREDATOR-PREY SYSTEM WITH BEDDINGTON–DEANGELIS FUNCTIONAL RESPONSE AND TIME DELAY
Authors: ZHANG HONG , GEORGESCU PAUL , CHEN LANSUN
Published: April 2008

This paper deals with an impulsive predator-prey model with Beddington–DeAngelis functional response and time delay, in which the evolution of the predators takes them through two stages, juvenile and mature. It is assumed that only mature predators are able to hunt for prey and reproduce and the time delay is understood as being the time spent by the juvenile predators from birth to maturity. It is first seen that the dynamics of the model can be completely determined through the use of a reduced system consisting of the equations for prey and mature predators, respectively. Using the discrete dynamical system determined by the stroboscopic map, one first determines the mature predator-free periodic solution of the reduced system. By means of comparison techniques, one then deduces sufficient criteria for the global stability of the mature predator-free periodic solution and for the permanence of the reduced system, which yield similar properties for the initial system. As a result, it is observed that time delay and pulses have a crucial effect upon the dynamics of our model.
Fluorescence Imaging of Membrane Dynamics
Authors: Groves Jay T. , Parthasarathy Raghuveer , Forstner Martin B.
Published: April 2008

Imaging membrane dynamics is an important goal, motivated by the abundance of biochemical and biophysical events that are orchestrated at, or by, cellular membranes. The short length scales, fast timescales, and environmental requirements of membrane phenomena present challenges to imaging experiments. Several technical advances offer means to overcome these challenges, and we describe here three powerful techniques applicable to membrane imaging: total internal reflection fluorescence (TIRF) microscopy, fluorescence interference contrast (FLIC) microscopy, and fluorescence correlation spectroscopy (FCS). For each, we discuss the physics underpinning the approach, its practical implementation, and recent examples highlighting its achievements in exploring the membrane environment.
Neural Stimulation and Recording Electrodes
Authors: Cogan Stuart F.
Published: April 2008

Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.
Regulation of Food Intake Through Hypothalamic Signaling Networks Involving mTOR
Authors: Woods Stephen C , Seeley Randy J , Cota Daniela
Published: April 2008

To maintain normal activity, single cells must assure that their energy needs and utilization are continuously matched. Likewise, multicellular organisms must constantly coordinate energy intake and expenditure to maintain energy homeostasis. The brain, and the hypothalamus in particular, plays a critical role in integrating and coordinating several types of signals, including hormones and nutrients, to guarantee such homeostasis. Like single cells, the hypothalamus also profits from intracellular pathways known to work as fuel sensors to maintain energy balance. One such pathway is the mammalian target of rapamycin (mTOR). mTOR integrates different sensory inputs to regulate protein synthesis rates in individual cells, and it has recently been implicated in the central nervous system to regulate food intake and body weight as well. This review provides an overview of the role of hypothalamic intracellular fuel sensors in the overall control of energy balance and discusses the potential contribution of these fuel-sensing mechanisms to the metabolic dysregulation associated with obesity.
Changes in Surface Stress of Au Electrode during Underpotential Deposition of Bi and Pb.
Authors: Seo Masahiro , Yamazaki Makiko
Published: April 2008

The changes in surface stress of Au electrode (mainly oriented to (111) plane) during underpotential deposition (UPD) of Bi and Pb were measured by a bending beam method to investigate the relation between surface stress and structure of the adlayer. The surface stress changed to the compressive direction as Bi- or Pb-UPD proceeded. The changes in surface stress to the compressive direction responded sensitively to the structural changes of the Bi- or Pb-adlayer. The biaxial modulus of (p x root 3)-2Bi monolayer or hexagonal close-packed Pb monolayer on Au (111) electrode was estimated from the relation between the changes in surface stress and the surface elastic strain of the monolayer obtained by surface X-ray scattering. The factors influencing the changes in surface stress during UPD of Bi or Pb were discussed in connection with the structural changes of the adlayer.
In Situ Stress Measurements During Al UPD onto (111)-Textured Au from AlCl3-EtMeImCl Ionic Liquid
Authors: Stafford G. R. , Beauchamp Carlos
Published: April 2008

In situ stress measurements were made during Al underpotential deposition (upd) onto (111)-textured Au from Lewis acidic aluminum chloride - 1-ethyl-3-methylimidazolium chloride using the wafer curvature method. The surface stress response consists of three distinct features. In the potential range of 1.2 V to 0.6 V the surface stress moves in the tensile (positive) direction which we attribute to the desorption of AlCl4- from the Au surface. This is consistent with adsorbate-induced stress models that appear in the literature. At the start of Al upd, the surface stress moves in the compressive direction, in contrast to the tensile stress expected based on the positive lattice misfit. We attribute this compressive stress to the formation of Al-Au bonds which partially satisfy the bonding requirements of the Au surface atoms, thereby reducing the tensile surface stress inherent to the clean Au surface. In the latter stages of Al upd, the surface stress once again moves in the tensile direction which we attribute to Al-Au alloying.
Mechanisms of Cu Electroless Plating onto Si(100) in Diluted HF Acid Solutions Containing CuSO4 or CuCl2
Authors: Dos Santos Sebastião G. , Hashimoto Alexandre , Hasenack Claus
Published: April 2008

Presented in this work are the mechanisms of Cu plating onto (100) Si surfaces in diluted hydrofluoric acid (D-HF) solutions containing CuSO4 or CuCl2. For D-HF/CuSO4 baths, it was observed that: (a) Si dissolution occurs; (b) For each atom of Cu which plates, one atom of Si is consumed; (c) Si oxidation occurs at the Cu/Si interface; (d) Bubbles of an inflammable gas were uniformly distributed over the Cu films. Also, for D-HF/CuCl2 baths, it was observed that: (e) Si dissolution occurs; (f) for each two atoms of Cu which plate, one atom of Si is consumed; (g) Oxygen was detected across the Cu films; (h) No bubble of gas appeared. Based on these observations, Si oxidation followed by silicon oxide etching was inferred to occur during Cu plating in D-HF/CuSO4 baths and Si dissolution induced by fluorine ions was inferred to occur during Cu plating in D-HF/CuCl2 baths.
An XAFS Study of Nickel Chloride in the Ionic Liquid 1-Ethyl-3-Methyl Imidazolium Chloride/ Aluminum Chloride
Authors: Roeper Donald , Cheek Graham T. , Pandya Kumi , O'Grady William
Published: April 2008

Nickel chloride was studied with cyclic voltammetry and X-ray absorption spectroscopy in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Acidic melts display metal stripping peaks which are not observed in the basic melt. EXAFS analysis shows that the nickel is tetrahedrally coordinated with chloride ions in the basic solution. In the acidic solution the nickel is coordinated by six chloride ions that are also associated with aluminum ions.
Spectroelectrochemistry of [(bpy)2Ru(tatpp)]Cl2, a Photocatalyst for Hydrogen Generation
Authors: Lezna Reynaldo O. , De Tacconi Norma R. , MacDonnell Frederick
Published: April 2008

The mononuclear ruthenium(II) complex [(bpy)2Ru(tatpp)]2+ (with bpy = bypyridine, tatpp = 9,11,20,22-tetraaza tetrapyrido[3,2-a:2'3'-c:3",2"-l:2"',3"']-pentacene) is photoactive and capable of proton-coupled electron transfer reactions. Electrochemical characterization in acetonitrile and aqueous media indicates that four electrons are accepted by the tatpp ligand of this complex. A rich array of electroreduced and protonated products was determined by UV-visible transmittance and reflectance spectroelectrochemistry. The multiple-electron uptake capability and appropriate energy levels in this complex is shared by its analog, the dinuclear [(bpy)2Ru(tatpp)(bpy)2]4+ complex, and therefore both are considered potential photocatalysts for hydrogen generation. Their photocatalytic lifetime was found significantly longer than the standard [Ru(bpy)3]2+ photocatalyst.