bluuebunny/crossref_metadata_2025 huggingface dataset:
The continuing case for the Renshaw cell
Authors: Alvarez Francisco J. , Fyffe Robert E. W.
Published: July 2007

Renshaw cell properties have been studied extensively for over 50 years, making them a uniquely well‐defined class of spinal interneuron. Recent work has revealed novel ways to identify Renshaw cells in situ and this in turn has promoted a range of studies that have determined their ontogeny and organization of synaptic inputs in unprecedented detail. In this review we illustrate how mature Renshaw cell properties and connectivity arise through a combination of activity‐dependent and genetically specified mechanisms. These new insights should aid the development of experimental strategies to manipulate Renshaw cells in spinal circuits and clarify their role in modulating motor output.
Exercise hyperaemia: magnitude and aspects on regulation in humans
Authors: Saltin Bengt
Published: July 2007

The primary function of the cardiovascular system is to supply oxygen to tissues and organs in the body. When muscles contract the aerobic demands are met by an increase in oxygen delivery both at the systemic and the regional levels, a match that is very close and holds at submaximal exercise and when small muscle group contract also at vigorous intensities. The level of muscle perfusion reached is 250 ml min−1 (100 g)−1 in muscle of sedentary subjects and in endurance‐trained athletes 400 ml min−1 (100 g)−1 has been reported. These levels of peak exercise hyperaemia equal what has been observed in other species. One consequence of these high muscle blood flows is that the human heart cannot support an optimal blood flow in whole body exercise (arms and legs combined) and sympathetically mediated vasoconstriction, also in arterioles feeding active limb muscles, contributes to matching peripheral resistance in order to maintain blood pressure. Respiratory muscles appear to have a higher priority for a blood flow than limb and torso muscles. There is no consensus in regard to which locally produced substances elicit the vasodilatation when muscle contracts. In addition to NO, data are presented for various metabolites of arachidonic acid and also on ATP, possibly released from the red cells. Using blockers of nitric oxide synthase (l‐NMMA or l‐NAME) and the enzymes producing epoxyeicosatrienoic acid (EET) (sulpaphenozole or tetraetylammonium chloride) or prostaglandins (indomethacin), muscle blood flow may be reduced by up to 25–40%. Evaluating the exact role of ATP has to await further studies in humans and especially the use of specific ATP receptor blockers.
Solidification Microstructure Evolution Model for Laser Cladding Process
Authors: Cao Y. , Choi J.
Published: July 2007

The laser cladding process inherently includes multiscale, highly nonlinear, and non-equilibrium transport phenomena due to nonuniform and rapid heat flow caused by the laser and the material interaction. In this work, a process model of solidification micro-structure evolution for the laser cladding process has been studied by utilizing a phase-field method. The phase-field method has become a widely used computational tool for the modeling of solidification micro-structure evolution with the advantage of avoiding tracking the interface explicitly and satisfying interfacial boundary conditions. In the present work, the numerical solutions of a phase-field model have been analyzed. The linking of the macroscale process and solidification microstructure evolution was examined by considering the relationship of macro- and micro-parameters. The effects of melt undercooling and anisotropy on the solidification micro-structure have also been studied. The predicted results with different undercoolings were compared with the microsolvability theory and a good agreement was found. Different solidification morphologies of different locations in the melt-pool are also investigated. To quantitatively study the effect of heat flux on the dendritic growth, the dendrite tip analysis was carried out. It was observed that the dendrite tip that grows in the same direction with the heat flux shows a much higher velocity than a tip that grows in the opposite direction of the heat flux.
Technical Brief: Asymptotic Temperature Distribution in a Simulated Combustion Chamber
Authors: Vyas Anand B. , Majdalani Joseph
Published: July 2007

In an axisymmetric model of a solid rocket motor, a cylindrical combustion chamber with porous walls is considered. For a posited range of operating parameters, the energy equation is perturbed and linearized using the dimensionless Péclet number. The possibility of circumventing chemical reactions while retaining the essential physics of the problem is explored. This is accomplished by artificially introducing a distributed heat source above the propellant surface. The resulting energy equation is then solved to zeroth order. The analytical solution and corresponding temperature maps are verified qualitatively using comparisons with numerical simulations of the combustion chamber.
Influence of Phonon Dispersion on Transient Thermal Response of Silicon-on-Insulator Transistors Under Self-Heating Conditions
Authors: Escobar Rodrigo A. , Amon Cristina H.
Published: July 2007

Lattice Boltzmann method (LBM) simulations of phonon transport are performed in one-dimensional (1D) and 2D computational models of a silicon-on-insulator transistor, in order to investigate its transient thermal response under Joule heating conditions, which cause a nonequilibrium region of high temperature known as a hotspot. Predictions from Fourier diffusion are compared to those from a gray LBM based on the Debye assumption, and from a dispersion LBM which incorporates nonlinear dispersion for all phonon branches, including explicit treatment of optical phonons without simplifying assumptions. The simulations cover the effects of hotspot size and heat pulse duration, considering a frequency-dependent heat source term. Results indicate that, for both models, a transition from a Fourier diffusion regime to a ballistic phonon transport regime occurs as the hotspot size is decreased to tens of nanometers. The transition is characterized by the appearance of boundary effects, as well as by the propagation of thermal energy in the form of multiple, superimposed phonon waves. Additionally, hotspot peak temperature levels predicted by the dispersion LBM are found to be higher than those from Fourier diffusion predictions, displaying a nonlinear relation to hotspot size, for a given, fixed, domain size.
Practical applications for global positioning system data from solid waste collection vehicles
Authors: Wilson Bruce G , Agar Betsy J , Baetz Brian W , Winning Anne
Published: July 2007

Studies of municipal solid waste collection systems have traditionally relied upon information collected from time and motion studies or truck logs. This type of data collection has been expensive, the volume of data collected has been small, and the reliability of the data has been suspect. A recent project in Hamilton, Ontario, monitored five municipal solid waste collection vehicles using a global positioning system (GPS) as an alternative to traditional data collection methods. The study found that the GPS data are reliable, accurate, and suitable for a range of solid waste planning purposes. Data collection was automatic and relatively inexpensive. Analysis of the data identified significant differences in the performance of the vehicles on different routes. Data collection using GPS is an improvement over traditional data collection methods, but the large volume of data generated will provide challenges for waste managers. Key words: data collection, global positioning system, municipal solid waste, refuse collection, automatic vehicle location.
Impact on water distribution system biofilm densities from reverse osmosis membrane treatment of supply water
Authors: Meckes Mark C , Haught Roy C , Kelty Keith , Blannon Janet C , Cmehil David
Published: July 2007

The quality of potable water is such that the concentration of nutrients available for growth of microorganisms within distribution systems is limited. In such systems carbon is often the growth limiting nutrient. Research conducted in the Netherlands has indicated that low levels (<10 μg/L) of available organic carbon in water is sufficient to maintain an actively growing population of heterotrophic, or organic carbon utilizing, bacteria in aquatic systems. However, the ability of commercially available and cost effective technologies to achieve such low concentrations of assimilable organic carbon in full-scale water systems is doubtful. Reverse osmosis (RO) systems have been used for many years to effectively remove contaminants from source waters. We challenged a water distribution system simulator (DSS) with water from a municipal system and water that was treated using an RO system under two concentrations of residual free chlorine to evaluate the effect of this disinfectant on biofilms in contact with low nutrient water. Our results showed that biofilm densities in the DSS carrying low nutrient RO treated water were lower than biofilm densities taken from the DSS when it carried water directly obtained from a municipal system.Key words: water distribution systems, reverse osmosis, biofilms, heterotrophic plate count, HPC, chlorine, assimilable organic carbon.
Evaluating Summer Rainfall through a Multilayered Largetooth Aspen Community
Authors: Clements John R.
Published: July 2007

This paper presents results of measurements, made separately for each of four canopy layers, of throughfall and stemflow in a multilayered stand of largetooth aspen (Populus grandidentata Michx.). Each canopy layer is identified by the predominant woody or fern species. Equations describe relationships between stemflow, stem size, and storm size, and between throughfall and storm size. In general, stemflow per stem per storm increased as both stem size and storm size increased, the latter having the greater effect. The equations varied with species. General stemflow equations were constructed to calculate stemflow per stem per storm for tree sizes and storm sizes within the measured range. Throughfall per storm increased as storm size increased, but at different rates for different canopy layers. Monthly budgets of interception, stemflow, and net rainfall for the various canopies, separately and together, were computed for the summer months of 1969 using the stemflow and throughfall equations, measured gross rainfall during all summer storms, and data on canopy structure for four plots within the stand. Interception by all canopies together amounted to 22 to 46% of monthly gross rainfall. Interception from the bracken fern canopy alone was 3 to 9%. Stemflow was about 8 to 17% of the monthly gross rainfall. The highest proportion of total stemflow was from bracken fern. Net rainfall was 54 to 78% of the monthly gross rainfall.
EcologyDevelopment of Dwarf Mistletoe (Arceuthobium) Infections on Western Hemlock, Shore Pine, and Western Larch
Authors: Smith R. B.
Published: July 2007

Newly dispersed seeds, established infections, and individually tagged shoots of hemlock dwarf mistletoe on western hemlock and shore pine, and established infections and individual shoots of larch mistletoe on western larch were examined periodically for up to 7 years, Infections on hemlock first appeared as swellings, some of which were visible during the first year after seed dispersal. Aerial shoots appeared in the second year. By the end of the third year most infections exhibited both swellings and aerial shoots. On all three hosts, mature mistletoe fruit were produced occasionally in the fourth year but generally not until the fifth year. Most female aerial shoots bore at least one crop of flowers during their existence, however, only half produced mature fruit. Aerial shoots varied in their life span from less than 1 year up to 7 years. The average was 2 to 3 years. One female shoot on larch bore five successive crops of flowers. The fastest longitudinal growth of mistletoe endophytic system occurred on western larch and the slowest was on shore pine. All infections were nonsystemic in that the endophytic system was largely confined to the swollen portions of the hosts.
Absence of "Rest" in the Cambium of Douglas-fir
Authors: Worrall John
Published: July 2007

Parts of whole plants were given a cold treatment to break rest, so that the interactions of tops and lower stems could be assessed with regard to their effect on cambial and bud growth. The cambium of seedlings of an interior British Columbia provenance of Douglas-fir was shown to have no endogenously imposed dormancy. Its activity, at least in the first 3 months of growth, was controlled strictly by the activity of the buds and shoots. However, in late June, and presumably under the influence of long photoperiods, cambial activity was initiated in those unchilled plants that showed no bud activity. In other unchilled plants, cambial activity occurred below and adjacent to adventitious shoots. The vertical and horizontal distributions of cambial activity, and the type of wood formed, were the same in chilled and unchilled cambia, provided the buds had been chilled.Lower stem chilling promoted the growth of adventitious shoots, but these were suppressed by growth of the terminal buds. Growth of terminal buds was not affected by the treatment of the lower stem. The plant material used had a chilling requirement of 29 days.
Moisture Storage Capacity and Postplanting Patterns of Moisture Movement from Seedling Containers
Authors: Day R. J. , Skoupy J.
Published: July 2007

A study was made on the movement of water from permeable-, partially-permeable-, and impermeable-walled seedling containers, filled with either peat or a peat and mineral soil mixture, into sand and loam planting soils. Irrespective of container type, there was rapid outward movement of from 15 to 39% of moisture initially stored in the containers to the surrounding soil within a few days of planting. Distinct wetting front patterns emanating from each type of container suggested that the path and eventual location of the moving moisture may be more critical for seedling survival than the amount moving into the surrounding planting soil. Radial moisture movement from the interface between the container and the soil to the soil surface from permeable- and partially-permeable-walled containers (Jiffy peat pot and Conwed tube) may aggravate evaporational losses. Elimination of radial moisture movement from an impermeable-walled container (Ontario tube) and limitation of outward flow from the open bottom to the root zone appear to be advantageous for seedling survival. Specifications for redesign of seedling containers for reforestation work are suggested.
Relative Precision of Two-Dimensional Systematic Sampling as a Function of Nonrandomness Index
Authors: Payandeh Bijan , Paine David P.
Published: July 2007

Stepwise multiple regression with logarithmic transformations was employed to establish relationships between the relative precision of systematic sampling and indices of nonrandomness. Results indicate that the relative precision of systematic sampling may be expressed as a function of the index of nonrandomness. Such relationships not only may vary from stand to stand but also may vary greatly depending on the variable of interest.
Resistance to Cronartiumribicola in Pinusmonticola: Genetic Control of Needle-Spots-Only Resistance Factors
Authors: McDonald G. I. , Hoff R. J.
Published: July 2007

Full-sib families of western white pine seedlings obtained by crossing phenotypically resistant parents were inoculated with a mixed population of Cronartiumribicola basidiospores. Families segregated into resistant and susceptible plants along patterns suggesting that the needle-spots-only resistance mechanism is controlled by two independent recessive genes.
Crown Shape in Open- and Forest-Grown Balsam Fir and Black Spruce
Authors: Honer T. G.
Published: July 2007

Crown-radius equations developed from measurements taken on open-grown balsam fir and black spruce were applied to forest-grown trees of the same species. For that part of the crown considered to be growing free of aerial competition, radii were estimated to within ±1.5 ft (±45.7 cm) at the 5% significance level. It was concluded that those portions of balsam fir and black spruce crowns estimated to be growing free of aerial competition are not significantly different from similar portions of open-grown trees of the same height and species. Coefficients and related statistics for the general crown-radius equation, CR = a1 L + a2LH + a3L2/H + a4L2, are given.
Variation with Crown Position and Leaf Age in Content of Seven Elements in Leaves of Pinusbanksiana Lamb.
Authors: Morrison I. K.
Published: July 2007

Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) were examined in September, 1969, in leaves of different ages from different parts of the crowns of twelve 30- to 33-year-old Pinusbanksiana Lamb. growing in a natural stand on coarse glacio-fluvial soil in northern Ontario. Although considerable tree-to-tree variability did occur, it was not sufficient to obscure differences related to crown position and leaf age, except in the case of N, where no trends were demonstrable. Foliar P, K, and Mg concentrations were shown to decrease with increasing leaf age, whilst foliar Ca, Fe, and Mn concentrations were shown to increase. From top to bottom of the crown, foliar P, K, and Fe concentrations decreased, whilst Ca and Mn concentrations increased. For Mg, no trend relative to crown position was discernible. Coefficients of variation were calculated and compared as were numbers of sample trees needed for statistically reliable samples.
Biomass of Fine Roots in a White Spruce Plantation
Authors: Safford L. O. , Bell Susan
Published: July 2007

Biomass of fine roots (≤3 mm diameter) in a white spruce (Piceaglauca (Moench) Voss) plantation in Maine was estimated at 696 ± 224 g/m2 or 3 kg per tree. Data consisted of 10 samples collected in midsummer from the top 45 cm of an imperfectly drained, silt loam, alluvial soil. Variation among individual samples was great, but appeared to be independent of distance to and size of closest tree. Results of this study compare favorably with published estimates of 2–3 kg per tree for other conifers in different parts of the world. The adequacy of this kind of study for understanding tree–soil relationships is discussed.
R-55 Rodent Repellent: Effect on Germination in Douglas-fir and Western Hemlock.
Authors: Edwards D. G. W. , Olsen Patricia E.
Published: July 2007

Coating Douglas-fir and western hemlock seeds with R-55, a rodent repellent, seriously reduced normal germination. Acidifying the latex sticker, or adding graphite powder, had no effect. If seeds were coated first with latex, more R-55 could be applied without significantly increasing germination losses. Both stratification and dry storage of R-55 coated seeds increased germination losses. Treatment differences detected by normal germination percentages were also reflected in germination values. Observations based on total (normal + abnormal) germination obscured the effects of the various coatings.
Lignin Utilization I. Kinetics of Base-Catalyzed Condensation Reactions of Lignin Model Compounds
Authors: Troughton G. E. , Manville J. F.
Published: July 2007

Rates of formation were measured for the base-catalyzed condensation reactions occurring between 4-alkylguaiacol compounds and their 6-methylol derivatives over the temperature range 85.5–100 °C. It was found that both the intercondensation reaction between the 4-alkylguaiacol compound and its 6-methylol derivative and the self-condensation reaction of the latter compound occurred at significant rates. In the 4-propylguaiacol – 4-methyl-6-methylolguaiacol system, the above two condensation reactions occurring in this system had the same activation energies, 35 kcal/mol. Similarly, in the 4-methylguaiacol – 4-propyl-6-methylolguaiacol system these two condensation reactions had equivalent activation energies, but slightly lower than in the former system, 32 kcal/mol. The kinetic results found for the model guaiacol compounds in this study demonstrate the possibility that a lignin-derived compound having more than one reactive position can be developed into a phenolic-type resin.
The Rate of Upward Advance and Intensification of Dwarf Mistletoe on Immature Western Hemlock
Authors: Richardson K. S. , Kamp B. J. van der
Published: July 2007

The rate of upward advance and intensification of dwarf mistletoe on immature coastal western hemlock were determined by reconstructing the infection history of individual trees from data on age, height above ground, and sex of mistletoe infections present at the time of observation. The vertical rate of spread was 30 ± 4 cm/year in a dense stand (750 trees per hectare, 19 m in height) and 65 ± 4 cm/year in an open stand (250 trees per hectare, 26 m in height). This compares with height growth of the trees of 33 and 58 cm/year in the two stands, respectively. The number of new infections per year increased logarithmically with time, doubling roughly every 4 years. An asymtotic stabilization of the rate of intensification over the last 6 years probably reflects crown closure. The results suggest that dwarf mistletoe may not be a serious threat to thrifty, immature, dense, coastal hemlock stands in southern British Columbia, unless such stands are overtopped by infected residual trees.
Cone-Induction Response of Douglas Fir to Form of Nitrogen Fertilizer and Time of Treatment
Authors: Ebell Lorne F.
Published: July 2007

Cone production increases of 2.5, 5.0 and 1.5 times that of control were obtained the year following treatment with 400 lb nitrate nitrogen per acre (1 lb/acre = 1.12 kg/ha), applied 6 weeks before vegetative bud break, at the start of bud break, and 10 days after the midpoint of the bud break period, respectively, on 20-year-old Douglas fir (Pseudotsugamenziesii (Mirb.) Franco.). Cone counts of 15, 26, 72, 142 and 155 were obtained from 0, 200, 400, 800 and 1600 lb nitrate nitrogen per acre, applied to 13-year-old trees during early bud break. Ammonium nitrogen, applied at the same rates and times, was ineffective for stimulation of cone production on either age of tree. There were no differences in rate of accumulation of total nitrogen in buds and foliage, shoot-growth responses, or total number of buds per shoot due to form of nitrogen. Nitrate treatment enhanced cone production through a reduction in bud failure during the shoot elongation period. These results suggest responses are not primarily due to improved mineral nutrition, but to a specific chemical stimulation from critically timed changes in type of nitrogen metabolism. Possible influences of temperature and rainfall on natural cone crop periodicity and on proper timing of nitrate treatment are discussed.
The Occurrence of Hybrid Swarms of Red and Black Spruces in Central New Brunswick
Authors: Manley S. A. M.
Published: July 2007

The data obtained by rating 50 plots in red × black spruce populations throughout central New Brunswick with a hybrid index indicate that red and black spruces have hybridized extensively. In the New Brunswick Lowland, gentle slopes and flat uplands form a continuum between characteristic habitats, permitting extensive contact between the two species. Where a considerable zone of contact was present, hybrid populations were established. Selection pressure is apparently strong, for despite the ideal opportunities for contact and the fertility of the hybrids, parental species remain phenotypically pure in their respective characteristic habitats (as far as these could be defined). The composition of hybrid populations was related to the extent of resemblance of 'intermediate' sites to parental site preferences. Introgressed black spruce predominated in hybrid populations, possibly due to the overriding influence of disturbances such as fire, logging, and damage to red spruce types by spruce budworm.
A New Approach for the Evaluation of Wood from Fertilized Trees
Authors: Sastry C. B. R. , Kozak A. , Wellwood R. W.
Published: July 2007

A new approach is presented to evaluate the effects of fertilizer application on wood properties of Douglas-fir, in particular weight of tracheid and its length. A specially developed quartz ultra-microbalance was used to weigh tracheids (holocellulose and alpha cellulose skeletons), from wood formed by trees treated with four different formulations (urea, NPK, (NH4)2SO4, NH4NO3).Following the year of fertilization, tracheid weight decreased or remained static for 1 or 2 years; subsequently there was an increase in the weight of individual cells. Highly significant correlations (R2 more than 64%) were found between length of tracheid and weight of carbohydrate material in it. Variations in cell weight following fertilizations, for the most part, were associated with changes in tracheid length.Although the study was not intended as a statistical sampling for the species, the results nevertheless illustrate that qualitative differences attributable to treatment composition (urea vs. NPK vs. (NH4)2SO4) exist, in that some treatments resulted in less weight of alpha cellulose per unit length of tracheid, when compared with normal wood tracheids. This reduction in cellulose fraction was suggested as a possible factor for differences observed in gross wood specific gravity in wood of some fertilized trees.
Overwinter Food Reserves of Potted Engelmann Spruce Seedlings
Authors: Ronco Frank
Published: July 2007

Lipid, protein, and hemicellulose concentrations of potted Engelmann spruce (Piceaengelmannii Parry) seedlings varied relatively little during the winter, and were nearly the same in December as the following June. Concentrations of reserve carbohydrates, in contrast, were lower in June, but the decrease was probably not important since the magnitude was no greater than the variability observed during winter. Thus, food reserve trends did not appear to support a hypothesis that mortality of planted seedlings was caused by overwinter depletion of food reserves.
Origin and Development of Aspen Root Suckers
Authors: Schier George A.
Published: July 2007

The origin and development of adventitious shoots (suckers) from the roots of trembling aspen (Populustremuloides Michx.) are described. Root suckers originate from newly initiated meristems, preexisting primordia, or suppressed short shoots, but the first two are probably the most important in sucker production. Preformed shoot primordia, protuberances from the phellogen, appear to occur on roots throughout the entire aspen range. Evidence was found of suppressed short shoots in aspen roots but not of suppressed buds buried in the periderm. Vascular trace shows that the developing sucker responds to polarity in the root; it grows distally as it extends inward and basipetally to the root cambium. Lenticels on aspen roots are illustrated.
Heart Rot of Black Spruce in Ontario. I. Stem Rot, Hidden Rot, and Management Considerations
Authors: Basham J. T.
Published: July 2007

A total of 6553 black spruce (Piceamariana (Mill.) B.S.P.) trees of commercial size were sampled throughout the range of this species in Ontario. Four distinct types of rot occurred in the merchantable boles, accounting for 3% of the volume. In black spruce, rot develops much earlier and more extensively below stump height (particularly in roots) than it does above stump height. Trees growing on drier, generally upland sites were faster growing and shorter lived than those sampled on wetter, generally lowland sites. Site, based on moisture regime, and tree age were both significantly related to the incidence of heart rot within the merchantable bole. Trees on drier sites, and the faster growing trees on all sites, were more susceptible to stem rot. The growing use of measures to accelerate the growth rate of black spruce, such as fertilization or site improvement by drainage, may raise productivity but it is also liable to increase the incidence of root and stem rot markedly.
Ethylene and the Regulation of Growth in Pine
Authors: Brown K. M. , Leopold A. C.
Published: July 2007

When branches of white pine are stressed by tying into loops, marked increases in the ethylene content of the internal atmosphere are noted. When an ethylene-generating paste is applied to localized regions, growth in diameter is increased there. It is suggested that ethylene may serve as a natural stimulator of radial growth associated with physical stress such as results from wind action.
Effect of Water Stress on Photosynthesis, Respiration, and Transpiration of Four Abies Species
Authors: Puritch George S.
Published: July 2007

The relationship between water stress and rates of net photosynthesis, respiration, and transpiration was determined for four Abies species native to Canada. Net photosynthesis, after an initial optimum rate, declined in three phases as water stress increased, viz. a rapid linear rate of decline, a second more gradual reduction and, finally, a steady rate of zero net photosynthesis. Of the four species, photosynthesis of A. grandis was affected the least by water stress, whereas that of A. balsamea was affected the most. Respiration declined at about the same water stress as photosynthesis, but was only reduced to between 40–75% of the maximum rate, depending on the species. Transpiration declined at similar water stresses to those of photosynthesis and after an initial decline, continued at between 10–30% of the maximum rate at water stresses up to 35 bars.
Seasonal, Daily, and Hourly Growth of Height and Radius in Norway Spruce
Authors: Worrall John
Published: July 2007

Daily height increment of trees was measured throughout two growing seasons as was 2-day radial increment of 212 of the same trees in the second season. The relationships between phenological variables and total growth, and the effect of environment on short term growth were assessed. Inferences taken from the latter data were tested on seedlings under more controlled conditions in the laboratory. The arbitrarily defined dates of initiation and cessation of growth, and the grand period growth rates were read from the growth curves. The respective simple r2 values between these variables and height growth were 0.10, 0.40, and 0.71, and r2 for the multiple regression of height growth and these variables was 0.94; for radial growth these values were 0.07, 0.56, 0.64, and 0.94. Length of the growing season and grand period growth rate were positively correlated. Dates of growth initiation and growth cessation were also positively correlated.Daily height growth varied considerably, depending strongly on temperature and relative humidity. The latter was associated with both a change in growth rate and a physical (nongrowth) change in size. Radial growth varied less, and depended less on environmental conditions. Minimum daily radius occurred several hours after the occurrence of maximum xylem sap tension.In seedlings, dimensional changes were very rapid on change of water stress. Day height growth rate was higher than night growth rate, presumably because of current photosynthate use.
Bark Thickness and Bark Resin Cavities on Young Lodgepole Pine in Relation to Hylobiuswarreni Wood (Coleoptera: Curculionidae)
Authors: Cerezke H. F.
Published: July 2007

Some patterns of bark thickness and bark resin cavity size, density, and their proportionate area in the inner bark on lateral roots, root-collar, and lower stem of 20–25-year-old lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) are described in relation to the oviposition and larval feeding-zone of the weevil, Hylobiuswarreni Wood. The oviposition and feeding-zone occurred where bark thickness was maximal, but where the density of cavities and their proportionate area occupied in the bark were low.
Growth and Transpiration of Black Locust Seedlings in Soil with Incorporated Cetyl Alcohol
Authors: Chaney William R. , Kozlowski Theodore T.
Published: July 2007

Growth of Robiniapseudoacacia L. seedlings was reduced by incorporation of cetyl alcohol into the soil in a greenhouse experiment. Transpiration on a leaf area basis was increased.
Small plots with unplanted plot border can distort data in biomass production studies
Authors: Zavitkovski J.
Published: July 2007

In small, dense and open-sided plantings of hybrid poplars, the edge effect extended through several rows, tree mortality increased and diameter at breast height (DHB), dry weight of individual trees, foliage weight, and leaf area index decreased from the border row to the center rows. Edge trees next to unplanted border trees tend to spread outward, thus intercepting solar radiation from a larger area than the area delineated by lower stems. When an oscillating irrigation system is used, the inner rows may receive only a fraction of the water border trees receive. This may be partly responsible for the extent of "edge effect" in this and similar studies. These irregularities could create serious problems in interpreting the results from small plantings. Some ways of reducing edge effect in production studies are proposed.
Biomass distribution and above- and below-ground production in young and mature Abiesamabilis zone ecosystems of the Washington Cascades
Authors: Grier Charles C. , Vogt Kristiina A. , Keyes Michael R. , Edmonds Robert L.
Published: July 2007

Biomass distribution and above- and below-ground net primary production were determined for 23- and 180-year-old Abiesamabilis (Dougl.) Forbes ecosystems growing at 1200-m elevation in the western Washington Cascade Range. Total organic matter accumulations were 427.0 t•ha−1 in the young stand, and 1247.1 t•ha−1 in the mature stand. Aboveground tree and detritus biomass were 49.0 t•ha−1 and 130.2 t•ha−1, respectively, in the young stand compared with 445.5 t•ha−1 and 389.4 t•ha−1 in the mature stand. Net primary production (NPP) was 18.3 t•ha−1 in the young stand and 16.8 t•ha−1 in the mature stand. Belowground dry matter production was 65% of total net production in the young stand and 73% of total net production in the mature stand. Conifer fine root production was 35.9% of NPP in the young and 66.4% of NPP in the mature stand. This apparent shift in fine root production as a proportion of NPP may be related to detritus accumulation.
Phytosociological changes in understory vegetation following timber harvest in northern Minnesota
Authors: Outcalt Kenneth Wayne , White Edwin H.
Published: July 2007

Impacts on the understory of a balsam fir (Abiesbalsamea (L.) Mill.) – paper birch (Betuiapapyrifera Marsh.) stand, caused by winter and spring full-tree logging and by winter tree-length logging which was followed by summer burning, were monitored for two growing seasons after overstory harvest. New species invaded full-tree logging sites, while compositional changes on the burned area were due primarily to the disappearance of species. Prescribed burning on the tree-length logging area prevented the quick increase in density of woody species that occurred on full-tree harvested sites. However, understory production increased on all sites, and by the end of the second season aboveground biomass was 3847, 4516, and 2604 kg/ha on the winter full-tree, spring full-tree, and winter tree-length plus burning sites, respectively, compared with 942 kg/ha on the uncut control.The major factors causing differences were prescribed burning and snow cover during harvest operations. Since our results concur with previous findings and appear predictable, resource managers can choose the technique best suited to specific objectives. However, no matter which system is used, the same core species will persist afterward, and if succession is allowed to continue, an understory will develop similar to that existing before harvest.
Epicormic branching in Rocky Mountain Douglas-fir
Authors: Bryan James A. , Lanner Ronald M.
Published: July 2007

The origin and morphology of epicormic branches in Rocky Mountain Dougas-fir (Pseudotsugamenziesii var. glauca (Beissn.) Franco) was studied by dissecting pole-sized trees. Epicormic shoots arose from buds on first-order branches, not as first-order axes buried in the bark of the trunk. The buds are suppressed 9–14 years before elongating. Epicormic shoots often produced buds at basal positions which elongated to form epicormic clusters.Intermediate trees tended to have more epicormics in the lower crown than dominants and codominants. Epicormics were significantly more frequent at higher elevations. The effects of aspect and slope were not significant.Douglas-fir stands in California and Idaho had substantially fewer trees with epicormics than stands in Utah, Wyoming, or Montana. Frequency of epicormics appears to be under genetic control. The appearance of epicormics does not require outside catastrophic influence, but is a routine event that occurs as shaded limbs decine in vigor. This habit appears to occur in several other coniferous genera.
Dieback and stump senescence following decapitation of eucalypts in relation to auxin and phenols
Authors: Blake T. J.
Published: July 2007

Decline and death in totally defoliated, decapitated seedlings of Eucalyptusobliqua L'Her. was associated with a decrease in electrical impedance ratio and an increase in inhibitor concentrations and phenol leakage from tissue slices and sap expressed from the lower stems. These changes did not occur or were less marked in E. viminalis Labill. seedlings which survived decapitation. Presence of a single, small, upwardly directed shoot on decapitated E. obliqua seedlings or certain concentrations of indole-3-acetic acid delayed or prevented seedling decline in this susceptible species. It was concluded that leakage of compartmented phenols and (or) decline in auxin levels may play a role in stump senescence. Released phenols may be the primary determinant in seedling decline or may reflect changes in levels of a shoot-produced hormone such as auxin.
Thigmomorphogenesis: changes in the morphology and chemical composition induced by mechanical perturbation in 6-month-old Pinustaeda seedlings
Authors: Telewski Frank W. , Jaffe M. J.
Published: July 2007

Seedlings of five half-sibs (seedlings that share a commom maternal parent) of Pinustaeda L. exposed to a bidirectional mechanical perturbation for 6 months exhibited a reduced rate of stem elongation and a reduction in the length of both juvenile leaves and needles. Of the five half-sibs tested, two different anatomical mechanisms of radial enlargement could be identified. Two half-sibs exhibited increased radial growth in the xylem parallel to the direction of the perturbation and no change in the axis perpendicular to the perturbation. Two exhibited a reduction in growth perpendicular to the perturbation with no change in the axis parallel to the perturbation. One half-sib appears to be intermediate between the two other pairs of half-sibs.An overall increase in extractable compounds was observed in the organic solvent fraction of mechanically perturbed seedlings. The amount of lignin appeared to remain fairly constant, and there was no change in the amounts of holocellulose or water extractable compounds.
Effects of thinning and nitrogen fertilization on branch and foliage production in Douglas-fir
Authors: Brix H.
Published: July 2007

The effect of two levels of thinning (zero and [Formula: see text] of basal area removed) and three levels of nitrogen fertilization (0,224, and 448 kg N/ha) on crown development of codominant, 24-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees was studied over a 5- to 7-year period. Thinning and heavy ferilization separately increased needle mass per tree after 7 years by 90% and, when combined, by 271%. Yearly needle production peaked 2–3 years after fertilization and resulted from an increase in needle size, needle number per shoot, and number of shoots produced. Maximum foliage mass per tree was reached 4–7 years after fertilization. Thinning effect on needle production was lower initially, but increased throughout the study period. A continuing foliage production in branches low in the crown contributed to thinning effect on foliage mass and crown size. Foliage distribution was affected most in the top half of the crown by fertilization and in the bottom half of the crown by thinning. Fertilization increased branch elongation at all crown heights, but thinning alone had no effect on crown width down to whorl 12.
Comparison of early and late timing of spray applications for control of spruce budworm in Quebec
Authors: Blais J. R. , DeBoo R. F. , Auger M.
Published: July 2007

An experiment was conducted in the Lower St. Lawrence region of Quebec in 1978 to determine (1) the validity of aerial spray applications of aminocarb timed against emerging L2 larvae of the spruce budworm (Choristoneurafumiferana (Clem.)) as well as (2) the relationship of timing spray applications and success of treatment. Two successive applications timed at peak L4–L5 (regime C) gave better results than similar treatment at peak L2 and peak L4 (regime A). Reduction in larval population density, and the amount of foliage saved due to regime C were almost twice that obtained with regime A.
An irruption of deer mice after logging of coastal coniferous forest
Authors: Sullivan Thomas P. , Krebs Charles J.
Published: July 2007

This study describes an irruption of Peromyscusmaniculatus after clear-cut logging of a coastal forest. The abundance of deer mice increased seven to eight times above previous levels in an old field habitat adjacent to the clear cut. This outbreak occurred during and after a logging operation in the fall of 1973. Several alternative explanations for this irruption include increased reproduction or reduced mortality in the deer mouse population, immigration of mice from the surrounding undisturbed forest, or immigration of animals from the clear-cut area. We conclude that removal of timber has the capacity to trigger an irruption of deer mice.
An outline of a cost–benefit analysis of increased felling in Sweden
Authors: Johansson Per-Olov
Published: July 2007

For some years it has been claimed that there is a "shortage" of roundwood in Sweden. The purpose of this paper is to examine what is meant by this shortage and to estimate social benefits and costs of an increased supply of roundwood. The estimates indicate that it is profitable for the society to eliminate the excess demand (shortage) through an increased supply.
Genetically based differences in susceptibility of white spruce to the spruce bud moth
Authors: Quiring Dan , Turgeon Jean , Simpson Dale , Smith Allan
Published: July 2007

The susceptibility of white spruce, Piceaglauca (Moench) Voss, leaders to damage by the spruce bud moth, Zeirapheracanadensis Mut. & Free., was assessed for 72 half-sib families at four half-sib family test sites and in one seedling seed orchard in New Brunswick. Trees of intermediate height (1.5–3.75 m) were the most damaged, and damage in one year was positively correlated to damage in the next. During 2 consecutive years, half-sib family explained only 1% of the variation in damage when all four test sites were analysed together. However, half-sib family explained between 2.9 and 7.9% of the variation in damage at individual sites. At the four test sites, mean growth reductions of trees in the two most susceptible families were estimated to be approximately 30% higher than those of trees in the two least susceptible families. When all 72 families were ranked with respect to height, trees in the most susceptible and least susceptible families were ranked very poorly and highly, respectively. This suggested that trees in more susceptible families were smaller because of damage by the spruce bud moth. However, this pattern was observed at all sites, including one where bud moth damage was negligible. Thus even in the absence of damage by the spruce bud moth, trees in these least susceptible families had a greater growth rate, in terms of height, than trees in the most susceptible families. This indicates that selection for plant traits reducing susceptibility to bud moth may be compatible with breeding programs attempting to improve height growth. Implications of these results for tree improvement programs are discussed.
Biomass of tropical forests of south and southeast Asia
Authors: Brown Sandra , Gillespie Andrew J. R. , Lugo Ariel E.
Published: July 2007

Stand tables from forest inventories representing more than 22 × 106 ha of forests in tropical Asia were used to estimate aboveground biomass (point and 99% confidence interval). The mean inventory-based biomass for moist forests (225 Mg/ha) was lower than that reported by direct measurements for mature forests in the same region (350 Mg/ha), whereas the mean inventory-based biomass for dry forests (82 Mg/ha) was higher than estimates based on direct measurements (55 Mg/ha). Our analyses demonstrated that human use of the forests in tropical Asia is intense, leading to degradation. Between two national forest inventories of Peninsular Malaysia in 1972 and 1981, the total area and biomass of forests declined by 18 and 28%, respectively. Modeling land-use changes and carbon dynamics of tropical Asian forests must take into consideration human impact on vegetation because such use of forests reduces their biomass and may stimulate forest growth and carbon uptake.
Compatible variable-form volume and stem-profile equations for Douglas-fir
Authors: Rustagi Krishna P. , Loveless Jr. Robert S.
Published: July 2007

A simple measure of stem form derived from geometric principles provides a basis for compatible volume and stem profile equations. Height ratios corresponding to three diameter ratios provide this measure and are compared in simple linear regression equations that predict a cylindrical form factor using data from a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stem analysis study. Further comparisons with existing volume and stem profile models from the literature show substantial gains in reducing above breast height volume prediction errors. Advantages and limitations of the models in both a theoretical and field application context are discussed.
Production and distribution of seed and pollen cones on Larixlaricina trees in young plantations
Authors: Tosh Kathleen J. , Powell G. R.
Published: July 2007

Numbers and distributions of seed and pollen cones were assessed on 90 Larixlaricina (Du Roi) K. Koch trees of 5, 6, and 7 years. Respectively, 27, 90, and 96% of the trees bore seed cones and 0, 62, and 96% bore pollen cones. Numbers of seed cones per tree averaged 9, 206, and 390 and of pollen cones, 0, 42, and 838. Ninety-nine, 88, and 30% of the seed cones were borne laterally on long shoots. At ages 6 and 7 years, 22 and 2% of the pollen cones were borne laterally. Seed cones occurred equally on side or lower surfaces of parent long shoots, but pollen cones were mainly on lower surfaces. Lateral cones were mainly borne proximally on the parent long shoots at first production; later, some were medial and a few were distal. Proportions of short shoots bearing seed cones increased acropetally. More short shoots bearing pollen cones were medial than proximal or distal. At age 6, proximal short shoots bearing pollen cones exceeded distal ones: the reverse occurred at age 7. Seed-cone and pollen-cone zones were not separate in the crowns, but within any shoot category, seed cones predominated on stronger shoots and pollen cones on weaker shoots.