bluuebunny/crossref_metadata_2025 huggingface dataset:
Foliar and cortical monoterpenes in Sitka spruce: potential indicators of resistance to the white pine weevil, Pissodesstrobi Peck (Coleoptera: Curculionidae)
Authors: Brooks J. E. , Borden J. H. , Pierce Jr. H. D.
Published: April 2008

To determine whether a resistant chemotype to the white pine weevil, Pissodesstrobi Peck, could be identified, the relative composition of monoterpenes in weevil-susceptible Sitka spruce, Piceasitchensis (Bong.) Carr., was compared to that in apparently resistant trees. Foliar and cortical analysis of trees from Green Timbers Nursery in Surrey, Nootka Island, Sayward, and the Nass River Valley, B.C., revealed significant differences between 38 resistant and 60 susceptible trees. The foliage of resistant trees, compared with that of susceptible trees, had significantly lower amounts of isoamyl isovalerate at three sites and lower amounts of isopentenyl isovalerate at one site. Amounts of a α-pinene, β-pinene, camphene, and camphor were significantly higher in some resistant trees, but these differences were not consistent between sites. Myrcene, β-phellandrene, and limonene levels were much higher in the cortex of susceptible trees than the resistant trees from the Nass River and Green Timbers Nursery. Thus none of the monoterpenes, singly or in combination, is a consistent indicator of resistance to the white pine weevil. The two isovalerates could possibly be used as indicators of resistance. However, a broader spectrum of resistance characteristics should be employed if breeding for resistance is desired.
The centroid of tree crowns as an indicator of abiotic processes in a balsam fir wave forest
Authors: Robertson Alexander
Published: April 2008

Wave forests are rare and were previously known only in high altitude Abiesbalsamea forests in northeastern U.S.A. and in subalpine A. veitchii – A. mariesii forests in Japan. Wave forests have been discovered at several locations in Newfoundland, including a very large and unique wave forest extending over 100–150 km2 on the coastal plain of northwestern Newfoundland. The wave fronts, characterized by dead tree strips, are mostly sinusoidal with an axis aligned in the direction of the prevailing wind, are spaced 100–150 m apart, and move in 55-year cycles. Crest-shaped wave fronts are concave on the windward side, occur as random events, and leave a trailing edge to the right of the prevailing wind that becomes a sinusoidal wave front. Two types of wave cycles, uniformcycle and brokencycle, have been identified as regular and random events, respectively. This paper reports the initial results of a detailed study on the impact of wind on the dynamics of a wave forest and concentrates on the centroid as a measure of crown asymmetry useful for distinguishing between purely biotic (mainly competition) and abiotic (mainly wind) processes as the primary cause of crown asymmetry. The development of wave forests at Spirity Cove is described based on the hypothesis that longitudinal helical roll vortices are primarily responsible for their formation.
Regeneration and growth of lodgepole pine in small openings in the Alberta Foothills
Authors: Bernier P. Y.
Published: April 2008

A survey carried out in 13-year-old circular openings of 1, 2, 4, and 6 tree heights (H) in diameter, in a 1H east–west strip, and in a 20-ha clear-cut of similar ages shows that regeneration of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) in the 4H and 6H cuts is comparable with that of the larger clear-cut. Regeneration is poor in the 2H opening and nonexistent in the 1H circular openings. The 1H east–west strip shows good regeneration.
Leaf and root osmotic adjustment in drought-stressed Quercusalba, Q. macrocarpa, and Q. stellata seedlings
Authors: Parker William C. , Pallardy Stephen G.
Published: April 2008

The leaf and root tissue water relations of Quercusalba L., Quercusmacrocarpa Michx., and Quercusstellata Wang. seedlings before and after drought were examined to evaluate the occurrence and comparative extent of osmotic adjustment in seedlings of these species. Drought resulted in active osmotic adjustment in leaves of all three species, with decreases in osmotic potential at full tissue hydration and at the turgor loss point from 0.25 to 0.60 MPa. Active osmotic adjustment in Q. stellata, and increased root tissue elasticity in Q. macrocarpa and Q. alba, resulted in turgor loss of roots occurring at a water potential 0.36 to 0.66 MPa lower in drought-stressed than in well-watered seedlings. Species differed in tissue water relations only before drought, with Q. stellata exhibiting lower osmotic potentials than Q. alba and Q. macrocarpa. Estimates of the osmotic potential at full saturation were generally lower in leaves than in roots, but the osmotic potential at turgor loss was similar. Roots exhibited turgor loss at lower values of relative water content and experienced a more gradual decrease in water potential per unit water content during dehydration than did leaves. This response indicates greater relative tissue capacitance in roots than in leaves in these species.
Foliar analysis using near infrared reflectance spectroscopy
Authors: Wessman Carol A. , Aber John D. , Peterson David L. , Melillo Jerry M.
Published: April 2008

Near infrared reflectance spectroscopy was evaluated as a method for measuring nitrogen and lignin content in foliage of native forest and prairie species. Near infrared reflectance spectra (1590 to 2357 nm) were obtained for 163 samples of dried green leaves and leaf litter from 18 deciduous and 2 coniferous tree species. Forty additional spectra were obtained from grass species. Reflectance (R) spectra were recorded as log (1/R) and transformed to the first and second derivative of log (1/R). Multiple linear regressions, predicting wet chemistry values based on near infrared reflectance spectra, yielded correlation coefficients of 0.98 for Kjeldahl nitrogen and 0.78 for lignin, with standard errors of 0.11% for nitrogen and 2.9% for lignin. Results suggest that near infrared reflectance spectroscopy is very effective for rapid (approximately 2 min per sample) determination of foliar lignin and nitrogen and should be considered for use as a routine analytical method.
Marking forest insects: evaluation of two systems for the systemic introduction of rubidium into Douglas-fir trees
Authors: McLean J.A. , Tuytel J.
Published: April 2008

Mauget® and Medicap® systems were evaluated for the systemic introduction of RbCl into Douglas-fir trees in the University of British Columbia Research Forest, Maple Ridge, B.C. Single, double, and triple rings of devices were placed on trees and Rb levels in foliage were monitored every 2 weeks for 8 weeks. At 8 weeks, trees were felled and phloem and sapwood samples were collected. Wounding associated with the injection devices was evaluated. Triple ring Mauget® injectors gave best results with more than 1890 ppm Rb in leader foliage. Rb levels were evenly distributed by height and aspect throughout the study trees. Highest levels of Rb were found in phloem tissue and these were often 3 times those in adjacent sapwood. Greater wounding, measured by failure to lay down current year springwood, was associated with the Medicap® implants. Some of this was probably caused by our failure to fully insert and thereby seal the implants properly in the tree, and a second factor may have been Rb toxicity as the capsule and RbCl crystals dissolved. A single ring of Mauget® injectors and a double ring of Medicaps® resulted in foliar Rb concentrations high enough for labelling of defoliating insects. High phloem levels of Rb suggest that bark beetles feeding on these trees would also be well labelled.
Compaction by forestry equipment and effects on coniferous seedling growth on four soils in the Alberta foothills
Authors: Corns Ian G.W.
Published: April 2008

Soils developed on four parent materials (glaciolacustrine clay, clay loam till, coarse fluvial, and loamy eolian) in west-central Alberta were examined to determine residual effects of logging and use of site-preparation equipment upon soil bulk density. These studies were conducted on sites that were logged during the previous 24 years. Compaction was evident on all soils except those of the Summit association, which were dominantly Brunisolic Gray Luvisols developed on cobbly fluvial deposits of Tertiary age. Compaction was greatest on soils of the Marlboro association, which were dominantly Brunisolic Gray Luvisols developed on clay loam till. Soil bulk density values on the clear-cuts had recovered to those of the controls at comparable depth at ages ranging from 0 (Summit) to 17–21 years (Marlboro). Lodgepole pine and white spruce seedlings were grown on the four soils compacted in the laboratory to three bulk densities approximating the following field conditions: (1) those observed or expected immediately following logging and site preparation; (2) those observed 5–10 years after logging and site preparation; and (3) undisturbed control. In most cases, significant reduction in nine expressions of seedling growth (maximum root depth, maximum root depth in soil core, total weight, shoot weight, root weight, stem diameter, shoot height, seedling survival, and shoot weight: root weight ratio) was observed with increased bulk density.
Effects of thinning on water stress and growth in Douglas-fir
Authors: Aussenac Gilbert , Granier André
Published: April 2008

The effects of a systematic thinning (alternate row) on water stress and growth in a 19-year-old Douglas-fir plantation (Pseudotsugamenziesii var. menziesii Franco) was studied during 5 years in northeastern France. Thinning has an important effect on water balance. The increase of the soil water reserve led to a lower duration and level of water stress in the thinned plot, especially during the first 3 years after thinning. This study revealed a rapid evolution of the water balance, since the evapotranspiration ratio of the two plots (control and thinned) had increased from 0.83 during the 1st year to 1.03 during the 5th year after thinning. Together with microclimate influences, thinning increased tree growth substantially (more than 100%); this growth increase resulted from a higher growth rate and longer growth periods (from 26 to 49 days).
A modification of the Ek–Payandeh nonlinear regression model for site index curves
Authors: Newnham R. M.
Published: April 2008

A new nonlinear regression model for constructing site index curves is described that, unlike previous models based on the Chapman–Richards growth model, produces sets of curves that are constrained to pass through the appropriate height at the index age as well as through the origin. The model was tested on two sets of height–age data, one from published yield tables and the other from stem analyses, and was found to give a good fit in both cases. There was a minimum loss of accuracy compared with a similar, unconstrained model.
Influence de stress contrôlés sur la sensibilité du bouleau jaune au chancre godronien causé par Godroniacassandrae Peck f.sp. betulicola Groves
Authors: Desprez-Loustau M. L. , Dessureault M.
Published: April 2008

Water-, nutrient-, or cold-stressed yellow birch seedlings showed an increased susceptibility to Godroniacassandrae Peck f.sp. betulicola Groves only when inoculation took place at the end of the growing season or during the dormant season. The effect of water stress was related to an observed decrease in plant water potential. Nitrogen deficiency increased susceptibility and markedly reduced growth both in diameter and height. However, a phophorus deficiency did not affect the disease or diameter growth, although height growth was slightly reduced. Increased susceptibility caused by cold stresses was proportional to the intensity of the stress. Susceptibility of younger shoots was not increased as much as that of older ones. Results show that G. cassandrae is weakly aggressive on yellow birch, attacking only weakened plants or dying twigs on healthy trees.
Relationships between the moisture content of fine woody fuels in lodgepole pine slash and the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System
Authors: Trowbridge R. , Feller M. C.
Published: April 2008

Unsuccessful attempts to ignite slash resulting from the mechanical knocking down of lodgepole pine in west central British Columbia led to a short-term investigation of the relationship between the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System and the moisture content of various fine fuel components <1 cm in diameter. Of the types of fuel sampled, the moisture contents of B.C. Forest Service fuel moisture sticks and aged slash were similar to, and well correlated (r = 0.79 and 0.81, respectively) with, the equivalent moisture content calculated from the Fine Fuel Moisture Code. The Fine Fuel Moisture Code was not designed to relate to the moisture content of uncured fuels. Thus, the moisture contents of fresh living slash (material from knocked down trees still attached to living roots) and of fresh dead slash (material unattached to living trees that had not yet experienced a complete fire season in which to fully cure) were poorly correlated with moisture content (r = 0.16 and 0.42, respectively). The moisture content of the progressively curing, needle-bearing fresh dead slash was relatively high at the beginning of the fire season, but became similar to the moisture content during the first half of July. This suggests that the Fine Fuel Moisture Code can also be used to predict the moisture content of such fine slash after these fuels have cured for approximately 3 months during the snow-free period.
Gibberellin A4/7 enhances seed-cone production in field-grown black spruce
Authors: Ho Rong H.
Published: April 2008

Black spruce (Piceamariana (Mill.) B.S.P.) grafts growing in a seed orchard were sprayed with gibberellin A4/7, and grafts and trees in families growing in arboreta were sprayed with gibberellin A4/7 and (or) vitamin E from vegetative bud burst to the end of shoot elongation. Gibberellin A4/7 was very effective in promoting seed cones and 400 mg/L appeared optimal. Vitamin E at 1000 mg/L was not effective. Vegetative bud burst occurred in mid-May and shoot elongation ended in late June. Needle primordia were visible on the apices of newly formed buds at the end of June. Reproductive buds had fewer bud scales than vegetative buds. It appeared that potential reproductive buds terminated their bud scale initiation earlier. Gibberellin A4/7 application to promote seed-cone production should be carried out before bud-type differentiation. This coincides with the end of lateral shoot elongation.
Histoire récente des épidémies de la Tordeuse des bourgeons de l'épinette au nord du lac Saint-Jean (Québec): une analyse dendrochronologique
Authors: Morin Hubert , Laprise Danielle
Published: April 2008

The chronology of spruce budworm (Choristoneurafumiferana (Clem.)) oubreaks for the past 200 years has been reconstructed by dendrochronological analysis of balsam fir (Abiesbalsamea (L.) Mill.) and white spruce (Piceaglauca (Moench) Voss) samples from virgin forests, unaffected by insecticide spraying programs and recently protected against fires in the north and northwest of Lac Saint-Jean. Outbreaks began around 1974, 1944, 1909, and possibly, 1832. They are closely linked with those described in the Laurentide wildlife reserve. The frequency, duration and severity of growth rings suppression associated with outbreaks are similar to those registered during outbreaks in the southern forests, except for the 1974 outbreak, which was shorter and less severe. Other outbreaks registered in southern regions, where the proportion of balsam fir is higher, have reached this region where balsam fir populations are marginal. These results underline the importance of these ecological disturbances in the population dynamics of the host trees of the region.
Optimizing any-aged management of mixed-species stands. I. Performance of a coordinate-search process
Authors: Haight Robert G. , Monserud Robert A.
Published: April 2008

Optimal any-aged management problems for mixed-species stands have been solved for the first time. Problem formulation calls for periodic planting and harvesting controls to be applied without constraints on the stand age or size structure over time; classical definitions of both even- and uneven-aged management are, thus, subsets of this general any-aged management definition. The solution technique is a derivative-free, coordinate-search process called the method of Hooke and Jeeves. The optimizer incorporates without modification the Stand Prognosis Model, a single-tree simulator that is used extensively in the western United States. This paper focuses on sensitivity analysis and performance of the optimizer on problems with both short and long time horizons and with different definitions of the harvest controls. Superior harvest regimes are found by defining harvest controls with relatively wide diameter-class boundaries and with broad species groups. In all cases examined, there is variability in present value and harvest pattern associated with the choice of the starting point for the optimizer. The cause of these multiple optima is a nonconvex and discontinuous response surface produced by the single-tree simulator. This points out the need to examine the results from several random starts before making conclusions about optimal timber harvesting.
Growth and maintenance respiration in stems of Pinuscontorta and Piceaengelmannii
Authors: Ryan Michael G.
Published: April 2008

Stem maintenance respiration was linearly related to live-cell volume for lodgepole pine (Pinuscontorta var. latifolia Engelm.) from 4 to 36 cm dbh and for Engelmann spruce (Piceaengelmannii Parry) from 0 to 20 cm dbh. Sapwood contained greater than 80% of the total live-cell volume in stems. Bole surface area, commonly used to estimate tree respiration costs, poorly estimated stem maintenance respiration. At 15 °C, maintenance costs for lodgepole pine were 6.6 × 10−5 kg C•(kg C sapwood)−1•d−1. Stem respiration during the growing season, both corrected and uncorrected for maintenance, correlated well with annual stemwood growth. Annual stem maintenance respiration for trees and stands can be estimated using sapwood volume, sapwood temperature, and knowledge of respiratory behavior. Total respiration (construction plus maintenance) estimated using stem growth and a model of maintenance respiration was compared with actual respiration measurements integrated over a 100-d growing season. Estimated respiration agreed with the integrated measurements for Engelmann spruce, but overestimated the integrated measurements by 73% in lodgepole pine. These results suggest that estimates of stem respiration made during the growing season may be affected by transpiration.
A comparison of chronologies from tree rings
Authors: Riitters Kurt H.
Published: April 2008

Forty-five-year ring width index chronologies were estimated by five mean-value functions applied to 183 ring width series from four similar sites. The effects of autocorrelation on the comparisons among mean-value functions were explored by fitting Box–Jenkins models to individual-tree index series prior to pooling (prewhitening), and to the pooled chronologies obtained from the mean-value functions (postwhitening). Among the mean-value functions tested, the principal component scores and the biweight yielded the highest cross correlations between chronologies from different sites, whereas the average, the median, and the median polish did not perform as well. Prewhitening and postwhitening tended to decrease both intersite correlations and correlations between chronologies from different mean-value functions for the same site.
Growth and N status of Populus in mixture with red alder on recent volcanic mudflow from Mount Saint Helens
Authors: Heilman Paul E.
Published: April 2008

Eleven months after the May 1980 eruption of Mount Saint Helens in southeastern Washington, United States, three Populus clones were planted in an experiment on the Toutle River mudflow deposit. The trees grew at an abnormally slow rate and by 3 years were overtopped by a dense stand (14 600 ± 3600 trees/ha) of red alder seeded naturally onto the site. Over the 6-year period of the study, the total N content of the soil increased an average of 56 kg•ha−1•year−1•. Foliar N concentration in Populus increased significantly from a mean late summer – early autumn value in the 2nd year (1982) of 0.69% N to a value of 2.06% N at the end of the seventh growing season. The mean annual height growth of the largest Populus averaged <0.5 m/year in the first 3 years, increasing to an average of over 1.0 m/year in the 5th and 6th years. Fertilizer treatments with N (as urea) and N + P (as urea plus treble superphosphate) placed in the soil near the individual Populus at a maximum rate of 5.3 g N/tree increased height growth in the year of fertilization (1982) and the following year (the response in height growth for the 2 years totaled 64%). After 1984, no significant effects of fertilizer on height growth, total height, or diameter were evident. Nitrogen fertilization significantly increased foliar N concentration (1.54% N with the highest N treatment vs. 0.69% N in the control) in the year of treatment only. Phosphorus fertilization had no significant effect on growth or foliar P concentration. At 6 years, only 2% of the Populustrichocarpa Torr. & Gray clone and 13% of the tallest Populus hybrid were equal to or above the mean height of alder dominants and codominants (6.2 m). Additionally, the diameter growth of Populus was severely limited: the trees had only 8% of the cross-sectional area of "normal" trees for their height. Results indicated that on sites of low N such as the mudflow, Populus may not compete satisfactorily in mixture with alder. Such behavior is in sharp contrast to sites of high N, where red alder cannot compete with Populus.
Reproduction of salal (Gaultheriashallon) under forest canopy
Authors: Bunnell F. L.
Published: April 2008

Sexual and vegetative reproduction of salal (Gaultheriashallon Pursh) was measured under forest canopies of different closure. Sexual reproduction occurred only at ≤33% closure; vegetative reproduction occurred under sparse and dense closure. Crown closure influenced sexual reproduction primarily through interception of radiation and associated reductions in salal vigour. Irradiance had a greater influence on the mode of reproduction than did shoot density, and allocation of total reproductive effort (sexual plus vegetative) was contrary to optimality models, but consistent with resource limitation. No shoot <5 years old flowered; shared costs of flowering indicated physiological integration among salal shoots. Vegetative reproduction was negatively associated with age (r2 = 0.95), and 85% of the space occupied after 9 years of growth was occupied during the first 3 years. Under canopy the spatial pattern of salal shoots was better adapted to maintain plant persistence than to colonize new areas. Implications of salal's rates and modes of reproduction to forest and wildlife management are noted.
Comparison of methods for estimating forest overstory cover: differences among techniques
Authors: Bunnell Fred L. , Vales David J.
Published: April 2008

Thirteen techniques for estimating forest overstory cover or mean crown completeness were tested for differences in angle of view of the technique and interaction with mean crown completeness or height to base of live crown. With increasing angle of view from common locations, mean estimates of mean crown completeness increased and the standard deviation decreased. For techniques with angles of view >30° there was interaction among techniques with changing overstory cover. As mean crown completeness increased, the differences between wide- and narrow-angled techniques decreased and converged to 0 at a rate dependent on the angle of view. For most techniques the estimate of mean crown completeness increased with height to base of live crown. The more narrow the angle of view the greater was the effect of increasing height to base of live crown. Differences among techniques were those expected from basic trigonometry; they occur because wider angles of view are less likely to encounter only space without canopy. Attempts to develop relations between overstory cover and other factors (e.g., snow interception, understory growth) should use angles of view appropriate to the factor being studied.
Effects of preconditioning on carbohydrate and amino acid composition of osmotically stressed black spruce (Piceamariana) cuttings
Authors: Zwiazek J. J. , Blake T. J.
Published: April 2008

The effects of preconditioning on osmotic potentials and the composition of soluble carbohydrates and free amino acids were studied in ramets of black spruce (Piceamariana Mill. B.S.P.). Plants were grown in solution culture and preconditioned by exposure to increasing concentrations of polyethylene glycol, and their osmotic potentials and composition of free amino acids and soluble carbohydrates were determined. Preconditioning increased levels of soluble carbohydrates compared with unconditioned plants. When the preconditioned and unconditioned plants were subjected to a subsequent, more severe osmotic stress with polyethylene glycol, high levels of monosaccharides and certain amino acids were observed in both preconditioned and unconditioned plants. During stress, preconditioned plants had lower (more negative) osmotic potentials and contained slightly higher levels of amino acids, but carbohydrate levels did not significantly differ from unconditioned plants. The increase in free amino acids and carbohydrates was insufficient to explain the drop in osmotic potentials resulting from preconditioning treatment.
Analysis of chestnut and scarlet oak stump sprout growth
Authors: Tworkoski T. J. , Ross M. S. , Hopper G. M.
Published: April 2008

This paper describes stem unit development of chestnut (Quercusprinus L.) and scarlet oak (Q. coccinea Muenchh.) stump sprouts growing on mesic and xeric sites in the Ridge and Valley physiographic region of southwest Virginia. On xeric sites, scarlet oak sprouts produced longer stem units than chestnut oak sprouts, whereas chestnut oak produced more flushes than scarlet oak. However, seasonal height growth was the same for both species. On xeric sites, 39% of the chestnut oaks flushed at least three times compared with 9% on the xeric site. Stem unit length among flushes of chestnut oak was similar, regardless of site. In oaks, stem unit analysis can be useful for evaluating growth components that may affect regenerative success and subsequent stand yield.
Human vs. machine: identification of bat species from their echolocation calls by humans and by artificial neural networks
Authors: Jennings N. , Parsons S. , Pocock M. J.O.
Published: April 2008

Automated remote ultrasound detectors allow large amounts of data on bat presence and activity to be collected. Processing of such data involves identifying bat species from their echolocation calls. Automated species identification has the potential to provide more consistent, predictable, and potentially higher levels of accuracy than identification by humans. In contrast, identification by humans permits flexibility and intelligence in identification, as well as the incorporation of features and patterns that may be difficult to quantify. We compared humans with artificial neural networks (ANNs) in their ability to classify short recordings of bat echolocation calls of variable signal to noise ratios; these sequences are typical of those obtained from remote automated recording systems that are often used in large-scale ecological studies. We presented 45 recordings (1–4 calls) produced by known species of bats to ANNs and to 26 human participants with 1 month to 23 years of experience in acoustic identification of bats. Humans correctly classified 86% of recordings to genus and 56% to species; ANNs correctly identified 92% and 62%, respectively. There was no significant difference between the performance of ANNs and that of humans, but ANNs performed better than about 75% of humans. There was little relationship between the experience of the human participants and their classification rate. However, humans with <1 year of experience performed worse than others. Currently, identification of bat echolocation calls by humans is suitable for ecological research, after careful consideration of biases. However, improvements to ANNs and the data that they are trained on may in future increase their performance to beyond those demonstrated by humans.
Effect of environmental stress on fluctuating asymmetry in certain morphological traits in Drosophila ananassae: nutrition and larval crowding
Authors: Vishalakshi C. , Singh B. N.
Published: April 2008

The association of fluctuating asymmetry and phenotypic and genetic variability with environmental stress was investigated using poor nutrition and larval density as stresses on 10 recently collected isofemale lines of Drosophila ananassae Doleschall, 1858. Trait means for different morphological traits were reduced by stress, whereas phenotypic and genetic variability increased. The levels of fluctuating asymmetry and positional fluctuating asymmetry were similar in flies reared on poor and standard media. In constrast, there is a significant difference in both asymmetry measures in the flies reared at different larval densities for all traits. However, when asymmetry values across all traits were combined into a single index, composite fluctuating asymmetry, significant differences were found in males and females reared at different larval densities but not under nutritional stress. Moreover, composite fluctuating asymmetry is higher in males than in females, suggesting that males are more vulnerable to developmental stress. The results suggest that trait means are more sensitive to stress than fluctuating-symmetry measures and that the effect of stress is trait- and sex-specific. Generalizations based on the use of fluctuating asymmetry as an indicator of environmental stress in D. ananassae should therefore be used with caution.
Factors affecting the relationship between seed removal and seed mortality
Authors: Moore J. E. , Swihart R. K.
Published: April 2008

S.B. Vander Wall et al. (Ecology, 86: 801–806 (2005)) criticized seed dispersal studies that use seed removal as a proxy for seed predation, because secondary dispersal processes following removal are important to seed fates for many plants. We compared seed removal rates with direct estimates of seed mortality and another mortality index, based on a 3-year experiment that included five temperate deciduous tree species and four exclosure treatments designed to identify effects of different seed consumer groups. Patterns of seed removal rates generally did not match patterns of mortality. Removal and mortality rates were both highest in seed-poor years, indicative of response to food limitation, but annual food abundance interacted with seed type differently for removal rates than for mortality rates. The effect of exclosure type (access by different consumers) on removal rates was opposite its effect on mortality rates; seeds were removed fastest from exclosures that allowed access to tree squirrels (genus Sciurus L., 1758), but these seeds had the lowest mortality because Sciurus is an important seed disperser. We discuss types of studies in which seed removal may be a reasonable index of seed mortality, and we stress the importance of justifying assumptions concerning links between removal and predation.
Differential use of similar habitat by Harlequin Ducks: trade-offs and implications for identifying critical habitat
Authors: Heath Joel P. , Montevecchi William A.
Published: April 2008

Interactions between ecological processes operating at different scales are critical aspects of habitat suitability requiring careful consideration in conservation planning. Our previous research indicated that local abundance and demographics of subpopulations of Harlequin Ducks ( Histrionicus histrionicus (L., 1758)), structured in 11 river canyons in northern Labrador, were influenced by predation risk from nest-site-limited raptors. At demographic extremes, where raptors were absent, Harlequin Ducks were stable at high densities, with positive-projected growth, suggesting that they were at carrying capacity and a source of emigrants. In contrast, where raptors were abundant, low density, highly variable populations of ducks approached local extinction in some years, with subsequent increases suggestive of immigration rescue effects. A comparison of resources for Harlequin Ducks indicated no differences in habitat availability among these putative “source” and “sink” subpopulations. In the present study, we used multivariate analysis to identify habitat characteristics important for home-range use within these river canyons and to develop habitat suitability indices (HSI). Despite similar habitat availability, different characteristics were locally important. In a sink where predation risk was high, only danger-reducing habitat characteristics (i.e., overhang vegetation) were identified as important, whereas invertebrates was a predominant characteristic of the source HSI. Despite similar habitat availability, HSI developed in source and sink habitats would, respectively, over- and under-estimate regional habitat availability. Informed conservation and management strategies will therefore require integrating individual trade-offs about predation risk and resources into a multiscale context.
Territory dynamics and patterns of female recruitment in Red-winged Blackbirds (Agelaius phoeniceus)
Authors: Dickinson T. E. , Lein M. R.
Published: April 2008

The territorial boundaries defended by male Red-winged Blackbirds (Agelaius phoeniceus) shifted over the course of the breeding season. The establishment of new males in a colony, the redefinition of boundaries among neighbors, and the recruitment of new females were all related to changes in boundary locations. No significant correlations were found between harem size and either territory size or the abundance of preferred nesting sites. High rates of aggressive interactions did, however, coincide with the recruitment of new females and accompanied territory shifts. Many boundary changes were associated with the guarding by males of females that were showing interest in nest sites outside the area formerly defended by the male. If a female's behavior in an area precipitates conflicts among neighboring males, then it could be a mechanism whereby females simultaneously compare the attributes of males and influence the quality of their territories. Such a mechanism would ensure that a female obtains what she has determined to be the best available nest site and a male that can defend her choice. A more active role for females should be included in models of the evolution of mating systems.
A qualitative and quantitative study of the reproductive cycle of the giant scallop, Placopecten magellanicus, in the Bay of Fundy (New Brunswick, Canada)
Authors: Beninger Peter G.
Published: April 2008

The reproductive activity of a nearshore giant scallop (Placopecten magellanicus) population in the Bay of Fundy was studied over a 17-month period using qualitative histological staging, quantitative stereology, and gonosomatic index techniques. The major spawning period extended from August to late September in both years, and no winter resting period was observed. Larval metamorphosis and settlement from this major spawning could be expected from early September to early October. Histological examination revealed that 33% of the males sampled were in advanced stages of maturity in December and January. Although direct histological observation and stereology provide the most information, the gonosomatic index coupled with macroscopic gonad examination allows a rapid and accurate assessment of reproductive activity.
Mechanisms of filter feeding in immature Simulium bivittatum Malloch (Diptera: Simuliidae) and Isonychia campestris McDunnough (Ephemeroptera: Oligoneuriidae)
Authors: Braimah Stephen A.
Published: April 2008

Immatures of Isonychia campestris McDunnough and Simulium bivittatum Malloch, fed mixtures of six size classes of polystyrene particles, captured particles that were smaller than the pore spaces between filtering structures more efficiently than was expected if filters functioned only as mechanical sieves. Capture efficiency was highest for the smallest (0.5 – 5.7 μm) particles. Relative efficiencies of filters for capturing suspended particles by four aerosol filtration mechanisms show that interception and diffusive deposition are mechanisms by which smaller particles reach the filter surface. The latter mechanism is a better predictor of size distribution of 0.5- to 5.7-μm particles captured by both insects. Adhesion of particles to filtering structures is probably by hydrophilic–hydrophobic or ionic interaction between particles and filters.
Morphological variation in deer mice in relation to sex and habitat
Authors: Xia Xuhua , Millar John S.
Published: April 2008

Peromyscus maniculatus borealis were collected in two habitats with contrasting physiognomic features in the Kananaskis Valley, Alberta, in the summer of 1983. We tested for differences between sexes and habitats using 4 body measurements (body length, tail length, hind foot length, and ear length) and 10 cranial (including mandibular) measurements of 222 and 192 adult P. m. borealis, respectively. Body measurements of 132 juveniles and five cranial (including mandibular) measurements from 124 juvenile skulls were analysed similarly. When differences in body length were controlled, adult males had significantly longer hind feet than adult females. The mandible was also significantly longer in adult males than in adult females. We interpreted the longer hind foot length in adult males as an adaptation to provide greater mobility, and the differences in mandibular morphology as a consequence of differential habitat use between the two sexes. No significant differences were found between juvenile males and females. Sexual dimorphism appeared to be age dependent rather than size dependent when adults and juveniles of similar body size were analysed.
Succession and phenology of beetle faunas (Coleoptera) in the fungus Polyporellus squamosus (Huds.: Fr.) Karst. (Polyporaceae) in Silesia, Poland
Authors: Klimaszewski Jan , Peck Stewart B.
Published: April 2008

Data are presented on the beetle fauna and its succession and phenology on the fruiting bodies of the polypore fungus Polyporellus squamosus in the Wroclaw area of Silesia in southwestern Poland. Ninety-eight species of beetles (over 2000 specimens) in 20 families were found. Species are grouped according to four different stages of maturity of the fungus fruiting body. Beetles were numerically most abundant on the fungus in the stage before ripening of the spores, but the greatest species diversity was in the final senescent stage of the dry fruiting body. Greatest numerical abundance and species diversity occurred during May. Thirty-eight species are reported from this fungus for the first time. The beetles are tentatively grouped into ecological categories of mycetobionts, mycetophiles, and mycetoxenes.
Abundance, growth, and food supply of white suckers (Catostomus commersoni) in relation to lake morphometry and pH
Authors: Trippel Edward A. , Harvey Harold H.
Published: April 2008

Associations between the abundance, body growth, and food supply (chironomid and ephemeropteran larvae) of white suckers, and lake morphometry and water chemistry were determined for eight Ontario lakes. White sucker abundance was low in three deep–acid lakes, intermediate in two deep–circumneutral lakes, and high in three shallow–acid lakes. Abundance was negatively correlated with both maximum lake depth (r = −0.71) and mean lake depth (r = −0.67) and positively correlated with the morphoedaphic index (r = 0.67). Generally, 4-year-old white suckers were largest in deep–acid lakes, intermediate in size in deep–circumneutral lakes, and smallest in shallow–acid lakes. Fork length and somatic weight at age 4 were negatively correlated with white sucker abundance (r = −0.76 and −0.80, respectively), positively correlated with density of chironomid larvae (r = 0.62 and 0.68, respectively), and negatively correlated with pH (r = −0.67 and −0.70, respectively). The von Bertalanffy estimates of maximum attainable fork length (Lx) for both sexes were substantially larger in both deep–acid and deep–circumneutral than in shallow–acid lakes. Correlations indicated that oligotrophic lakes contain white suckers with a large Lx, the strongest correlation being with maximum lake depth (female Lx, r = 0.84; male Lx, r = 0.89).
Food habits of the Common Barn-Owl in British Columbia
Authors: Campbell R. Wayne , Manuwal David A. , Harestad Alton S.
Published: April 2008

The diet of the Common Barn-Owl, Tyto alba, in British Columbia was determined from analysis of 30 218 prey remains recovered from 11 787 pellets between 1941 and 1981. Small mammals were the main prey accounting for 98.0% of all remains, with rodents (80.1%) and insectivores (17.8%) the primary prey groups. Microtus townsendii accounted for nearly three-quarters of all prey and 84.3% of mammalian-prey biomass. Food habits varied among five geographical areas. Voles (Microtus spp.) and shrews (Sorex spp.) were primary and secondary prey, respectively, in all areas but Vancouver City, where Norway rats (Rattus norvegicus), house mice (Mus musculus), and birds (Columba livia, Sturnus vulgaris, and Passer domesticus) predominated. Microtus townsendii was the primary prey in all seasons (1973 and 1978), with autumn the season of highest numbers of voles. Other prey were inversely proportional to the incidence of microtines in the diet. Over 13 years, from 1967 to 1981, microtines accounted for between 65.3 and 84.5% of all prey items and their occurrence in the diet generally followed population trends of grassland mammals. A positive correlation between percent occurrence in the diet and population density was noted for the principal food, M. townsendii.
Computer analysis of polarized spacing patterns with special reference to the larvae of the black fly, Simulium vittatum
Authors: Eymann M. , Schmidt J. M. , Friend W. G.
Published: April 2008

A computer analysis of spacing patterns which makes fewer assumptions than either nearest-neighbour distance or plot frequency analysis techniques is described. This analysis determines if the spacing pattern is polarized in any direction, and can compensate for the possible effect of the size and shape of the organism on the spacing pattern. The output of the analysis is a two-dimensional frequency distribution which represents the likelihood of finding a neighbour near an average individual. This output can be represented by a two-dimensional map. The method requires a sample size greater than 50, and in its present form cannot assign statistical significance to the resulting probability distribution.
Interpatch dispersal of the cabbage butterfly
Authors: Fahrig L. , Paloheimo J. E.
Published: April 2008

The purpose of this project was to study the dispersal behaviour of female Pieris rapae (cabbage butterfly), with the goal of understanding the relationships between population abundance and dispersal mechanisms. Field studies indicated that (i) female flight orientation is not affected by the presence of a host plant patch, (ii) the number of eggs laid by a female on a patch is independent of patch size, at least within the range 18 to 18 000 plants, and (iii) dispersal rate of adult females from host plant patches is high. A model of egg abundance based on these assumptions was found to explain 85.4% of the variation in log egg abundance data taken from the literature. We suggest that, even though females disperse at high rates and are unable to orient towards host patches, populations maintain generally high abundances because host patches are common and widely distributed, and female flight paths are long. Both of these are expected to increase the probability of host detection.
Lethal effects of vanadium to two life stages of brook trout Salvelinus fontinalis (Mitchill)
Authors: Ernst W. R. , Garside E. T.
Published: April 2008

Alevins of brook trout (Salvelinus fontinalis) were less sensitive to vanadium than were yearlings, the 96-h LC50 being 24 and 7 mg V/L, respectively. "Lethal thresholds" were not attained during alevin exposures for 33 days and yearling fish exposures for 12 days. Vanadium solutions were also rendered less toxic by the addition of sulphuric acid and sodium hydroxide, suggesting that a toxic effect of vanadium is an increased loss of electrolytes from membrane surfaces.
A preliminary characterization of alkaline digestive proteases in the posterior midgut of the face fly, Musca autumnalis De Geer
Authors: Campbell F. C. , Houseman Jon G. , Morrison P. E.
Published: April 2008

Alkaline proteases in the posterior midgut of the face fly, Musca autumnalis De Geer, were identified using specific synthetic substrates and nonspecific substrate azocasein. Identification was confirmed with potential protease activators and inhibitors. Optimal azocasein hydrolysis occurred at pH 8.0 and substrate hydrolysis was inhibited by EGTA (ethyleneglycol-bis-(2-aminoethyl ether)-N,N-tetraacetic acid), tosyl-L-lysine chloromethyl ketone (TLCK), and soybean trypsin inhibitor (STI). Tryptic proteolysis was identified by maximal hydrolysis, at pH 8.0, of trypsin specific substrates BAPNA (benzoyl-DL-arginine-p-nitroanilide) and TAME (tosyl-L-arginine methyl ester). TAME hydrolysis was inhibited by PMSF (phenylmethylsulfonyl fluoride), STI, pepstatin A, and dithiothreitol (DTT), but BAPNA hydrolysis was inhibited only by STI and DTT. Chymotrypsin was demonstrated by maximal hydrolysis of BTEE (benzoyl-L-tyrosine ethyl ester) at pH 8.0 and DTT, PMSF, and STI inhibited hydrolysis of this substrate. Aminopeptidase activity was demonstrated by maximal hydrolysis of leucine-p-nitro-anilide at pH 8.0 and the peptidase was inhibited by o-phenanthroline. Carboxypeptidase A-like enzyme hydrolyzed hippuryl-DL-phenyllactic acid maximally at pH 7.5 and carboxypeptidase B showed maximum hydrolysis of hippuryl-L-arginine at pH 7.0. Both carboxypeptidases were inhibited by EDTA (ethylene diamine tetraacetic acid), EGTA, and DTT and carboxypeptidase A was also inhibited by PMSF.
Deposition of aluminum in the gill epithelium of rainbow trout (Salmo gairdneri Richardson) subjected to sublethal concentrations of the metal
Authors: Youson John H. , Neville Christine M.
Published: April 2008

Rainbow trout (Salmo gairdneri Richardson) were exposed to acid and sublethal concentrations of inorganic aluminum (1.6 μM at pH 6.1; 2.8 μM at pH 5.5, 5.0, and 4.5); aluminum was also administered in combination with organic acid at pH 4.5 and 5.0. The gill epithelium was examined by transmission electron microscopy and by electron probe X-ray microanalysis. Control fish at pH 7.3 without aluminum showed normal morphology but increased acidity and (or) decreased hardness resulted in a greater exposure of chloride cells at the epithelial surface. All fish exposed to aluminum had electron-dense particles on the surface of the respiratory (pavement) epithelial cells and chloride cells of the gills and most cells had these deposits in varying concentrations within cytoplasmic vacuoles and dense bodies. It was shown by X-ray microanalysis that the deposits contained aluminum. Increased acidity did not alter the pattern of distribution of aluminum particles but a heavy concentration of this metal followed the addition of organic acid. The accumulation of aluminum on and within epithelial cells and increased exposure of chloride cells in the gills could reflect decreased oxygen uptake and increased ion loss in trout, and probably are responsible for the toxicity of aluminum to fish in an acid environment.