bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal sustainability of groundwater-source cooling in Winnipeg, Manitoba
Authors: Ferguson Grant , Woodbury Allan D
Published: October 2005

Groundwater from the Carbonate Rock Aquifer is extensively used for cooling purposes in Winnipeg, Manitoba. This paper examines the factors affecting the magnitude and timing of temperature increases at production wells in groundwater-source cooling applications through numerical modeling and observations at a case study site. Generic simulations carried out using typical hydrogeologic parameters for the Carbonate Rock Aquifer suggested that temperature increases of a few degrees occur at a typical production well only a few years after the start of operation in a given system. Spacing of the wells and pumping rates were found to have a greater affect than material properties in a homogeneous aquifer. A case study of a thermal doublet in the Winnipeg area indicated, however, that heterogeneities are capable of causing a departure from the predicted temperatures of the generic models. The case study showed that it is possible to make reasonable predictions of the behaviour of the subsurface temperature field during thermal development of the Carbonate Rock Aquifer. Temperature records of the length used in this study will not be available in new developments, however, and efforts must be made to conduct more extensive field investigations to ensure that designs can properly account for geologic conditions.Key words: geothermal energy, fractured rock, Carbonate Rock Aquifer, Winnipeg, Manitoba, injection, heat flow.
Cyclic shear response of fine-grained mine tailings
Authors: Wijewickreme Dharma , Sanin Maria V , Greenaway Graham R
Published: October 2005

The mechanical response of three different types of fine-grained mine tailings is examined using data from constant-volume cyclic direct simple shear (DSS) tests. Under cyclic DSS loading, fine-grained tailings typically exhibit a cumulative decrease in effective stress along with progressive degradation of shear stiffness. The observed shear strain development due to cyclic mobility is similar in form to that of the previously observed cyclic shear response for natural silts. The cyclic resistance ratio (CRR) of laterite tailings is observed to increase with an increase in the initial effective confining stress (σ′vc). For this material, the dilative tendency due to stress densification seems to have overridden the contractive tendency due to the increase in confining stress. In contrast, the CRR of coppergoldzinc tailings is insensitive to the initial effective confining stress, suggesting a response similar to that of normally consolidated clay. The postcyclic maximum shear strength ratio (Su-PC/σ′vc) obtained from constant-volume monotonic DSS tests is noted to increase with a decrease in the void ratio. For the fine-grained tailings considered in this study, the liquefaction susceptibility predicted using commonly used empirical criteria is not always in agreement with the liquefaction triggering determined from cyclic DSS tests.Key words: tailings, liquefaction, cyclic stress ratio, postcyclic shear strength, direct simple shear testing.
Evaluation of the stability of anchor-reinforced slopes
Authors: Zhu D Y , Lee C F , Chan D H , Jiang H D
Published: October 2005

The conventional methods of slices are commonly used for the analysis of slope stability. When anchor loads are involved, they are often treated as point loads, which may lead to abrupt changes in the normal stress distribution on the potential slip surface. As such abrupt changes are not reasonable and do not reflect reality in the field, an alternative approach based on the limit equilibrium principle is proposed for the evaluation of the stability of anchor-reinforced slopes. With this approach, the normal stress distribution over the slip surface before the application of the anchor (i.e., σ0) is computed by the conventional, rigorous methods of slices, and the normal stress on the slip surface purely induced by the anchor load (i.e., λpσp, where λp is the load factor) is taken as the analytical elastic stress distribution in an infinite wedge approximating the slope geometry, with the anchor load acting on the apex. Then the normal stress on the slip surface for the anchor-reinforced slope is assumed to be the linear combination of these two normal stresses involving two auxiliary unknowns, η1 and η2; that is, σ = η1σ0 + η2λpσp. Simultaneously solving the horizontal force, the vertical force, and the moment equilibrium equations for the sliding body leads to the explicit expression for the factor of safety (Fs)or the load factor (λp), if the required factor of safety is prescribed. The reasonableness and advantages of the present method in comparison with the conventional procedures are demonstrated with two illustrative examples. The proposed procedure can be readily applied to designs of excavated slopes or remediation of landslides with steel anchors or prestressed cables, as well as with soil nails or geotextile reinforcements.Key words: slopes, factor of safety, anchors, limit equilibrium method.
The measurement of groundwater temperature in shallow piezometers and standpipes
Authors: Alexander Matthew D , MacQuarrie Kerry TB
Published: October 2005

Accurate measurements of in situ groundwater temperature are important in many groundwater investigations. Temperature is often measured in the subsurface using an access tube in the form of a piezometer or monitoring well. The impact of standpipe materials on the conduction of heat into the subsurface has not previously been examined. This paper reports on the results of a laboratory experiment and a field experiment designed to determine if different standpipe materials or monitoring instrument configurations preferentially conduct heat into the shallow sub surface. Simulations with a numerical model were also conducted for comparison to the laboratory results. Statistical analysis of the laboratory results demonstrates that common standpipe materials, such as steel and polyvinylchloride (PVC), do not affect temperature in the subsurface. Simulations with a finite element flow and heat transport model also confirm that the presence of access tube materials does not affect shallow groundwater temperature measurements. Field results show that different instrument configurations, such as piezometers and water and air filled and sealed well points, do not affect subsurface temperature measurements.Key words: groundwater temperature, temperature measurement, conduction, piezometers, piezometer standpipes, thermal modelling.
Mechanisms of setup of displacement piles in sand: laboratory creep tests
Authors: Bowman Elisabeth T , Soga Kenichi
Published: October 2005

A series of triaxial creep tests is described, with the aim of shedding light on the mechanisms behind displacement pile setup in granular soils. The stress path leading to the creep stages has been designed to mimic, as far as possible, the installation of a pile adjacent to an element of soil. A complex strain response is found with creep in dense sands at high stress ratio, with rotation of the creep strain vector over time. A new hypothesis, involving kinematically restrained dilation of the soil close to the pile shaft and soil ageing, is proposed to explain pile setup. Influences on the creep behaviour, and hence degree of setup, are found to be particle shape and strength, relative density, and rate of loading. The application of small cyclic perturbations during creep is found to accelerate the onset of volumetric dilation and hence is proposed to accelerate setup.Key words: creep, setup, displacement piles, laboratory testing, sands.
Dynamic modelling of entrainment in rapid landslides
Authors: McDougall Scott , Hungr Oldrich
Published: October 2005

Entrainment of path material is an important feature of many rapid landslides. The associated increases in volume and changes in flow character can significantly influence mobility. A simple material entrainment algorithm, based on the assumption of natural exponential growth with displacement, has been incorporated into a new computer model designed to simulate rapid landslide motion across 3D terrain. The user controls the growth rate and can also implement a change in rheology at the onset of entrainment. A hypothetical example is used to demonstrate the influence of the mass and momentum transfer assumptions. A back-analysis of the 1999 Nomash River landslide is included to show that the simple model is capable of simulating the bulk characteristics of a complex event involving substantial entrainment.Key words: landslides, debris flows, rock avalanches, entrainment, erosion, dynamic modelling.
Quantitative investigations of the hydraulic connection between a large reservoir and a buried valley aquifer in southern Alberta
Authors: Smerdon B D , Mendoza C A , McCann A M
Published: October 2005

Quantitative investigations, including two aquifer tests and development of a three-dimensional (3D) groundwater flow model, were required to determine the hydraulic connection between an irrigation reservoir and a buried valley aquifer in southern Alberta. Evidence of seepage was detected in the buried valley aquifer 10 km east of the Pine Coulee reservoir at the onset of filling in 1999, when the reservoir level exceeded an elevation of 1035 m above sea level (a.s.l.). Concern for an increase in the local water table and the creation of artesian conditions in the aquifer prompted this study to determine the approximate location of a seepage window that appeared to be connecting the reservoir and aquifer. Observations of hydraulic head in the aquifer during the pumping tests revealed a barrier boundary when the reservoir level was at an elevation of 1035 m a.s.l. and a recharge boundary condition when the elevation exceeded 1039 m a.s.l. These data were used to calibrate a 3D groundwater flow model, which was needed to determine the hydraulic properties and approximate location of the leakage zone. The quantitative investigation showed that seepage likely occurred through the sideslopes of the flooded coulee, rather than through the low-permeability coulee floor sediments or the embankment dam. Further simulations illustrated the expected seepage rates at various reservoir supply levels and the pumping rates required for relief wells installed in the buried valley aquifer to maintain historic aquifer hydraulic head. A brief postanalysis indicated that the forecasted pumping rates were only 15% lower than have been required to maintain preconstruction water levels in the buried valley aquifer.Key words: dams, seepage analysis, groundwater modelling, buried valley aquifer, pumping test.
Upper-bound solutions of three-dimensional passive earth pressures
Authors: Škrabl S , Macuh B
Published: October 2005

This paper presents a novel approach to the determination of passive soil pressures: using the upper-bound method within the framework of limit analysis theory. It is based on a three-dimensional, kinematically admissible, rotational, hyperbolical failure mechanism. The failure mechanism is composed of the central and two lateral bodies, which are connected by a common velocity field. This approach is similar to two-dimensional stability analyses, where the log spiral potential failure surface is considered. The front surface of the central body interacts with the retaining wall; the upper surface can be loaded by surcharge loading; and the log spiral segment defines the curved failure surface of the central part. The cross sections of the lateral bodies are in agreement with the cross section of the central body. On the outer side, they are laterally bounded by a curved and kinematically admissible hyperbolic surface, which is defined by enveloping the hyperbolical half cones and part of the case surface of the leading half cone. The results give values for the passive soil pressure coefficients that are for most cases lower than the values determined by the upper-bound method of limit analysis for a translational failure mechanism, as published in the literature.Key words: limit analysis, earth pressure, passive pressure, failure surface, soilstructure interaction.
Synthesis of fused pyrazolo-, isoxazolo-, pyrimido-, and pyridopyrimidines
Authors: Thokchom Herojit S , Nongmeikapam Anita D , Laitonjam Warjeet S
Published: October 2005

A systematic study of the synthesis of the 5,7-diaryl-4-oxo-pyrazolo[3,4-d]pyrimidin-6-thiones (3), 2-phenyl-5,7-bis(2′-methylphenyl)-4-oxo-pyrazolo[3,4-d]pyrimidin-6-thiones (4b), 2(3H)-3-phenyl-5,7-diaryl-4-oxo-pyrazolo[3,4-d]pyrimidin-6-thiones (5), 5,7-diaryl-4-oxo-isoxazolo[5,4-d]pyrimidin-6-thiones (7), 3,5,7-triaryl-2,3-dihydro-4-oxo-isoxazalo[5,4-d]pyrimidin-6-thiones (8), 2-amino-6,8-diaryl-5-oxo-pyrimido[4,5-d]pyrimidin-7-thiones (9), 3,4-dihydro-2-amino-4-phenyl-6,8-diaryl-5-oxo-pyrimido[4,5-d]pyrimidin-7-thiones (10), 3-cyano-6,8-diaryl-2,5-dioxo-pyrido[2,3-d]pyrimidin-7-thiones (11) from the condensation products 1 and 2, derived from 1,3-diaryl-2-thiobarbituric acids is described.Key words: synthesis, fused, pyrazole, isoxazole, pyrimidines.
One-step synthesis of Sb2O3 broom-like belts with controllable morphology
Authors: Zhao Qingrui , Zhang Xuanjun , Yang Qing , Xie Yi
Published: October 2005

A direct and simple surfactant- and template-free route has been developed for the controlled synthesis of Sb2O3 belt-like microstructures. By adjusting the reactant ratio between SbCl3 and urea under solvothermal reaction conditions, broom-like belts and rods of Sb2O3 have been successfully prepared. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS) has been used to characterize the phases and morphologies of the as-prepared products. A possible formation mechanism is also discussed.Key words: antimony trioxide, solvothermal synthesis, broom-like belts.
Spectroscopy and electrochemistry of new 6,6′-disubstituted-4,4′-bipyrimidine molybdenum(0) and tungsten(0) tetracarbonyl complexes
Authors: Ioachim Elena , Hanan Garry S
Published: October 2005

A new family of tetracarbonyl molybdenum(0) and tungsten(0) complexes based on new 6,6′-disubstituted-4,4′-bipyrimidine ligands was synthesized and characterized. The visible region of the absorption spectrum of each complex is dominated by a metal-to-ligand charge transfer band significantly lower in energy than the corresponding transition in 2,2′-bipyridine tetracarbonyl metal complexes. The 6,6′-substituents create a larger π-electronic system in the substituted bipyrimidines and are consequently better π acceptors than even the parent 4,4′-bipyrimidine. The absorption bands are shifted bathochromically with a decrease in solvent polarity.Key words: molybdenum and tungsten, nitrogen ligands, tetracarbonyl metal complexes, absorption spectroscopy, electrochemistry.
Characterization and identification of disintegrins inCrotalushorridusvenom by liquid chromatography and tandem matrix-assisted laser desorption ionization - quadrupole ion trap time-of-flight (MALDI-QIT-TOF) mass spectrometry
Authors: Galán Jacob A , Sánchez Elda E , Bashir Sajid , Pérez John C
Published: October 2005

Two disintegrins were purified from the venom of Crotalus horridus by multiple-dimension liquid chromatography (MDLC) (specifically C18 reverse phase (RP) high-performance liquid chromatography followed by size exclusion chromatography (SEC), and anion exchange chromatography (SCX)). Both disintegrins were subjected to mass spectrometry to determine their intact molecular mass, the number of disulfide linkages, and protein sequence, respectively. These disintegrins were named horrdistatin 1 (nominal mass, 7231 Da) and horrdistatin 2 (nominal mass, 7451 Da), and had IC50(inhibitory concentrations) of 12.5 and 16.2 nmol/L (at 50%), respectively. For sequence confirmation from the C-terminal end, both disintegrins were derivatized using chemical-assisted fragmentation (CAF) and subsequently unzipped via collision-induced dissociation (CID) by matrix-assisted laser desorption  ionization  quadrupole ion trap time-of-flight (MALDI-QIT-TOF) mass spectrometry.Key words: disintegrins, mass spectrometry, snake venom, Timber rattlesnake, Crotalus horridus.
Induced structural changes of a supported planar bilayer after exposure to halothane  A real-time atomic force microscopy study
Authors: Shamrakov L G , Cramb D T
Published: October 2005

Atomic force microscopy (AFM) was used to study the effect of the general anesthetic halothane on a supported DOPC phospholipid bilayer, under conditions of high anaesthetic loading. The presence of the anaesthetic in the lipid-induced restructuring of the supported bilayer, erosion of the bilayer from the mica surface, and the formation of lipid aggregates. Addition of halothane to lipid vesicles prior to adsorption on the mica surface inhibited the lysis of adsorbed vesicles and thus no planar bilayer formation was observed.Key words: lipid bilayer restructuring, atomic force microscopy, halothane, anesthesis.
Synthesis and structure of new trichloromethyl-β-diketones  5-Trichloromethylisoxazole and 5-isoxazolecarboxylic acid derivatives
Authors: Martins Marcos A.P , Brondani Sergio , Leidens Victor L , Flores Darlene C , Moura Sidnei , Zanatta Nilo , Hörner Manfredo , Flores Alex FC
Published: October 2005

An improved method for the synthesis of a new series of trichloromethyl-β-diketones including 1,1,1-trichloropentan-2,4-dione (2a), 1,1,1-trichloro-3-methylhexan-2,4-dione (2b), 4,4,4-trichloro-1-phenylbutan-1,3-dione (2c), 4,4,4-trichloro-2-methyl-1-phenylbutan-1,3-dione (2d), 2-trichloroacetylcyclohexanone (2e), 4-tert-butylcyclohexanone (2f), 4-tert-butylcycloheptanone (2g), and 4-tert-butylcyclooctanone (2h) is reported. A multinuclear NMR study showed that β-dicarbonyl compounds 2b and 2d2h are predominantly in the keto form and 2a and 2c are in the enol form. The trichloromethyl-β-diketones react with hydroxylamine hydrochloride leading to three sets of isoxazole derivatives.Key words: acetals, acylation, trichloromethyl-1,3-diketones, 2-trichloroacetylcycloalkanones, isoxazoles, cyclocondensation.
Convenient tetrahydropyranylation of alcohols and phenols by catalytic ferric sulfate hydrate (Fe2(SO4)3·xH2O)
Authors: Li Lingjun , Zhu Lizhi , Zhang Xinying , Zhang Guisheng , Qu Guirong
Published: October 2005

Ferric sulfate hydrate (Fe2(SO4)3·xH2O) is found to be an efficient heterogeneous catalyst for the tetrahydropyranylation of alcohols and phenols at ambient or near ambient temperature. In addition, selective monotetrahydropyranylation of symmetrical diols is achieved under similar conditions. The deprotection of THP ether and direct transformation of THP ether to the corresponding acetate by Fe2(SO4)3·xH2O is also studied. The simplicity of manipulation, mild conditions, reusable catalyst, good selectivity, and environment benign characters make this method a good alternative way for the THP protection of alcohols.Key words: tetrahydropyranylation, selective monotetrahydropyranylation, ferric sulfate hydrate, green chemistry.
One-pot conversion of β-aminocrotononitrile to secondary enaminonitriles including chiral ones  Application to synthesis
Authors: Chatterjee A , Mishra M , Chowdhury SK Dutta , Mahalanabis Kumar K
Published: October 2005

A highly efficient one-pot conversion of β-aminocrotononitrile to secondary enaminonitriles including chiral ones is described. In contrast to β-aminocrotononitrile, some of these N-substituted β-enaminonitriles on reacting with acid chlorides show a unique preference for C-terminal selection allowing preparation of pyrazoles without separation of regioisomers. In addition, use of secondary enaminonitriles also provided access to pyrazoles that are not obtainable with primary enaminonitriles owing to an exclusive preference for N-terminal selection.Key words: β-aminocrotononitrile, N-substituted enaminonitriles, regioselective, pyrazoles.
Oxazoline chemistry. Part VIII. Synthesis and characterization of a new class of pincer ligands derived from the 2-(o-anilinyl)-2-oxazoline skeleton  Applications to the synthesis of group X transition metal catalysts
Authors: Decken Andreas , Gossage Robert A , Yadav Paras N
Published: October 2005

The synthesis and characterization of a new and readily synthesized class of potentially anionic pincer ligands with C1 point group symmetries is described. These materials can be made via amide coupling of a 2-(2′-anilinyl)-2-oxazoline unit with picolinic acid; the incorporation of enantiopure oxazoline fragments facilitates the construction of chiral C1 pincers. Treatment of the free ligands with Pd metal sources leads to the formation of amidoPd pincer complexes in good yield. One of these Pd complexes has been characterized by single crystal X-ray diffraction methods, which confirms the proposed tridentate binding mode of the ligand and the formation of an amido NPd bond. The metal complexes have been shown to be suitable precusors for catalytically active Pd species that are useful for CC bond forming reactions, notably the Heck reaction under standard conditions. Key words: oxazoline, 4,5-dihydro-2-oxazole, palladium, pincer ligand, amido, Heck reaction.
Detection and quantification of Leptographium wageneri, the cause of black-stain root disease, from bark beetles (Coleoptera: Scolytidae) in Northern California using regular and real-time PCR
Authors: Schweigkofler Wolfgang , Otrosina William J , Smith Sheri L , Cluck Daniel R , Maeda Kevin , Peay Kabir G , Garbelotto Matteo
Published: October 2005

Black-stain root disease is a threat to conifer forests in western North America. The disease is caused by the ophiostomatoid fungus Leptographium wageneri (W.B. Kendr.) M.J. Wingf., which is associated with a number of bark beetle (Coleoptera: Scolytidae) and weevil species (Coleoptera: Curculionidae). We developed a polymerase chain reaction test to identify and quantify fungal DNA directly from insects. Leptographium wageneri DNA was detected on 142 of 384 bark beetle samples (37%) collected in Lassen National Forest, in northeastern California, during the years 2001 and 2002. Hylastes macer (LeConte) was the bark beetle species from which Leptographium DNA was amplified most regularly (2001: 63.4%, 2002: 75.0% of samples). Lower insectfungus association rates were found for Hylurgops porosus (LeConte), Hylurgops subcostulatus (Mannerheim), Hylastes gracilis (LeConte), Hylastes longicollis (Swaine), Dendroctonus valens (LeConte), and Ips pini (Say). The spore load per beetle ranged from 0 to over 1 × 105 spores, with only a few beetles carrying more than 1 × 103 spores. The technique permits the processing of a large number of samples synchronously, as required for epidemiological studies, to study infection rates in bark beetle populations and to identify potential insect vectors.
Phenotypic variation in growth and biomass distribution for two advanced-generation pedigrees of hybrid poplar
Authors: Wullschleger Stan D , Yin T M , DiFazio S P , Tschaplinski T J , Gunter L E , Davis M F , Tuskan G A
Published: October 2005

To assess the genetic control of biomass distribution in trees, phenotypic variation in the distribution of dry mass to stems, branches, leaves, coarse roots, and fine roots was examined in two hybrid poplar (Populus trichocarpa Torr. & A. Gray (T) × Populus deltoides Bartr. ex Marsh. (D)) families grown under field conditions. Family 331 was an inbred F2(TD × TD) pedigree, whereas family 13 was an outbred backcross BC1(TD × D) pedigree. Fractional distribution of total whole-tree biomass to shoots and roots during their establishment year averaged (±SD) 0.62 ± 0.09 and 0.38 ± 0.09, respectively, across 247 genotypes in family 331, and 0.57 ± 0.06 and 0.43 ± 0.06, respectively, across 160 genotypes in family 13. In contrast, fractional distribution of total biomass in 2-year-old trees was 0.79 ± 0.04 to shoots and 0.21 ± 0.04 to roots. Allometric analysis indicated that as trees increased in age, biomass was preferentially distributed to stems and branches, whereas distribution to roots declined. Quantitative trait loci (QTL) analysis for family 13 indicated 31 QTL (likelihood of odds >2.5) for traits measured. The percent phenotypic variation explained by any single QTL ranged from 7.5% to 18.3% and averaged 11.2% across all QTL. These results show that aboveground and belowground patterns of biomass distribution are under genetic control. This finding has wide-ranging implications for carbon sequestration, phytoremediation, and basic biological research in trees.
Deep subsoil nutrient uptake in potassium-deficient, aggrading Pinus resinosa plantation
Authors: Buxbaum C AZ , Nowak C A , White E H
Published: October 2005

Growth of Pinus resinosa Ait. (red pine) on a potassium-deficient sandy soil at the Charles Lathrop Pack Demonstration Forest in Warrensburg, New York, is influenced by fine-textured lenses at 23 m below grade. A possible mechanism for an observed increase in surface soil potassium over time is nutrient uptake by red pine roots penetrating into these fine-textured, subsoil layers, and subsequent cycling of these nutrients between foliage and surface soil horizons. To test this hypothesis, we applied nutrient tracers directly to the deep subsoil and measured their uptake over several growing seasons: Strontium was applied in 1989 and 1993, while rubidium-free potassium (the Rb/K reverse tracer method) was applied only in 1993. Trees treated in 1989 had significantly greater concentrations of foliar and bud strontium than control trees, and trees treated only in 1993 also demonstrated significant uptake of potassium 2 years after treatment. These effects were present regardless of whether the trees had been surface-fertilized with potassium five decades earlier. The results demonstrate the importance of subsoil nutrient pools in forest ecosystem function.
The establishment and development of oak forests in the Ozark Mountains of Arkansas
Authors: Soucy Rick D , Heitzman Eric , Spetich Martin A
Published: October 2005

The disturbance history of six mature white oak (Quercus alba L.)  northern red oak (Quercus rubra L.)  hickory (Carya spp.) stands in the Ozark Mountains of northern Arkansas were reconstructed using tree-ring and fire-scar analysis. Results indicate that all six stands originated in the early 1900s following timber harvesting and (or) fire. These disturbances initiated a pulse of oak-dominated establishment. Most sites were periodically burned during the next several decades. Abrupt radial growth increases in all stands during the 1920s to 1940s reflected additional disturbances. These perturbations likely provided growing space for existing trees, but did not result in increased seedling establishment. Thus, multiple disturbances were important in the origin and development of the stands studied. By the 1930s and 1940s, oak establishment was replaced by shade-tolerant, fire-intolerant non-oak species; few oak recruited into tree size classes after the 1950s. The decrease in oaks and the increase in non-oaks coincided with fire suppression. Few scars were recorded during the past 6070 years. Prescribed fire may be an important management tool in regenerating oak forests in northern Arkansas.
Human impact on size, age, and spatial structure in a mixed European larch and Swiss stone pine forest in the Western Italian Alps
Authors: Motta Renzo , Lingua Emanuele
Published: October 2005

Spatiotemporal development and human impact on dynamic processes were investigated in the mixed European larch (Larix decidua Mill.) and Swiss stone pine (Pinus cembra L.) subalpine forest of Lago Perso (Piedmont, Italy). We mapped and measured all 295 trees (DBH ≥4 cm) and 914 saplings (>10 cm height, <4 cm DBH) in a permanent plot (1 ha). One core per tree was extracted upslope at 50 cm height, and dendrochronological techniques were applied to reconstruct age structure and growth patterns. All of the data collected were stored in a GIS, and tree and stem crown maps were generated and analysed to quantify spatial patterns. Ripley's K(t) univariate and bivariate point pattern analyses were employed to assess the degree of spatial autocorrelation. Documentary research was conducted to reconstruct human land use. The stand is uneven-aged, and there were no obvious age cohorts or other evidence of major disturbances in the past. Stone pine saplings and trees and larch saplings exhibited a clumped structure. The same clumping was not so evident in larch trees. The observed structural changes are mainly related to human land use and grazing regime. Although human influence is still manifest, in the recent decades natural dynamics have become the predominant influence on the forest's structure and processes.
Changes in landscape composition and stand structure from 19452002 on an industrial forest in New Brunswick, Canada
Authors: Etheridge David A , MacLean David A , Wagner Robert G , Wilson Jeremy S
Published: October 2005

Detailed 19441947 cruise data and maps were used to compare species composition, age-class distribution, and stand structure between 1945 and 2002, for a 190 000 ha industrial forest in New Brunswick, Canada. Softwood forest area in 1945 and 2002 was similar, at 40% and 42%, respectively, but mixed hardwoodsoftwood decreased from 37% to 18%, and hardwood increased from 10% to 25%. Forest management from 1945 to 2002 resulted in the forest (1) becoming younger, with 86% of the trees >70 years old in 2002 versus 44% in 1945, (2) becoming denser, with 100300 more stems per hectare and 47 m2/ha more basal area in 2002, and (3) having less balsam fir (Abies balsamea (L.) Mill.)  31%66% in 1945 versus 4%38% in 2002 of basal area for stands with >30% softwood. Management reduced balsam fir to lower mortality associated with spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks. The area of old (≥70 years old, with ≥10 trees/ha ≥30 cm DBH) and large (≥70 years old, with ≥5 trees/ha ≥45 cm DBH) spruce-fir and mixedwood wildlife habitats decreased from 112 600 and 55 200 ha in 1945 to 8200 and 7200 in 2002, respectively, while hardwood habitat increased from 22 800 to 71 500 ha. Management increased timber production while maintaining similar softwood species composition, but altered age structure and areas of mixedwood and hardwood forest types.
Canadian national tree aboveground biomass equations
Authors: Lambert M-C , Ung C-H , Raulier F
Published: October 2005

The estimation of aboveground biomass density (organic dry mass per unit area) is required for balancing Canadian national forest carbon budgets. Tree biomass equations are the basic tool for converting inventory plot data into biomass density. New sets of national tree biomass equations have therefore been produced from archival biomass data collected at the beginning of the 1980s through the ENergy from the FORest research program (ENFOR) of the Canadian Forest Service. Since the sampling plan was not standardized among provinces and territories, data had to be harmonized before any biomass equation could be considered at the national level. Two features characterize the new equations: estimated biomass of the compartments (foliage, branch, wood, and bark) are constrained to equal the total biomass, and dependence among error terms for the considered compartments of the same tree is taken into account in the estimates of both the model parameters and the variance prediction. The estimation method known to economists as seemingly unrelated regression allowed the inclusion of dependencies among the error terms of the considered biomass compartments. Sets of equations based on diameter at breast height (dbh) and on dbh and height have been produced for 33 species, groups of hardwood and softwood, and for all species combined. Biomass predicted by the new equations was compared with that estimated from provincial equations to evaluate the loss of accuracy when scaling up from the regional to the national scale. Bias and error of prediction from the set of national equations based on dbh and height were generally more similar to those from provincial equations than to those of predictions from the set of equations based on dbh alone.
Germination, penetration, and infection by Arceuthobium americanum on Pinus banksiana
Authors: Brandt J P , Hiratsuka Y , Pluth D J
Published: October 2005

Information on the establishment of Arceuthobium americanum Nutt. ex Engelm. on its host, jack pine (Pinus banksiana Lamb.), is required to improve knowledge of this critical development stage and improve pest management. Laboratory and field observations on four populations of A. americanum seeds from Alberta collected in 2000 and 2001 and histological observations on one population were used to determine the timing and histopathology of parasite establishment on jack pine. Seed germination remained near zero until 110 d after placing seeds in storage; germination peaked after 230 d in 2001 and between 230 and 320 d in 2002. Interannual variation in germination timing at study sites was high. Interannual variation in percentage of germination was low, as was variation in percentage of germination from different seed sources. Germinated seeds of each seed source were significantly larger (48%) than seeds that did not germinate. Penetration at the base of spur shoots began during JuneAugust and usually continued until JuneJuly of the next year. The odds of infection when the germinant survived until the second growing season were 2655 times greater than the odds of infection when the germinant withered in the first growing season. Symptoms of infection usually occurred 1315 months after germination and were consistent for all seed sources and sites.
Successional pathways on different surficial deposits in the coniferous boreal forest of the Quebec Clay Belt
Authors: Lecomte Nicolas , Bergeron Yves
Published: October 2005

To infer successional pathways on different surficial deposits in northwestern Quebec, we combined the chronosequence approach to the study of within-stand species' vertical distribution. The deposits sustained different frequencies of postfire stand composition types and successional trajectories. After fire, Picea mariana (Mill.) B.S.P. dominated all stands on organic deposits, while shade-intolerant species dominated the canopy in over 30% and 60% of stands, respectively, on fine- and coarse-textured deposits. In the absence of fire, P. mariana eventually dominates the canopy of all stands on every deposit. However, as the frequency of Larix laricina (DuRoi) K. Koch and Abies balsamea (L.) Mill. in old stands (>100 years) are, respectively, positively and negatively correlated with the deposits' paludification potential, changes in composition in this landscape appear to be driven by the species' tolerance to shade and paludification. Structural changes were characterized by the replacement of closed dense stands by open stands. The diversity of P. mariana stand structures within the youngest age-classes suggests that fire severity may also explain the diversity of stand structures within this landscape. As among-stand structural diversity decreases with increasing time elapsed since fire, converging structural development pathways may be occurring in this landscape.
Effects of an introduced pathogen on resistance to natural disturbance: beech bark disease and windthrow
Authors: Papaik Michael J , Canham Charles D , Latty Erika F , Woods Kerry D
Published: October 2005

In forests of eastern North America, introduced pathogens have caused widespread declines in a number of important tree species, including dominant species such as American beech (Fagus grandifolia Ehrh.). Most studies have focused on changes in forest composition and structure as a direct result of mortality caused by a pathogen. Our field studies of windthrow resistance in forests of northern New York and northern Michigan demonstrate that resistance of beech trees to windthrow is severely reduced by beech bark disease (BBD). This reduced resistance was primarily due to the increase in the probability of stem breaks of moderately and highly infected beech trees. The severity of BBD infection on individual trees has a significant negative effect on resistance to windthrow. We tested potential consequences of this for long-term composition and structure in these forests by using a simulation model, SORTIE. We found that species such as yellow birch (Betula alleghaniensis Britt.) and eastern hemlock (Tsuga canadensis (L.) Carr.) increased in basal area primarily because of the effect BBD had on the creation of new seedbed substrates. Our results highlight the indirect effects that host-specific pathogens can have on community dynamics and species coexistence in forests.
Precision and accuracy of three alternative instruments for measuring soil water content in two forest soils of the Pacific Northwest
Authors: Czarnomski Nicole M , Moore Georgianne W , Pypker Tom G , Licata Julian , Bond Barbara J
Published: October 2005

We compared the accuracy and precision of three devices for measuring soil water content in both natural and repacked soils and evaluated their temperature sensitivity. Calibrations were developed for a capacitance instrument (ECH2O), a time domain reflectometry cable tester (CT), and a water content reflectometer (WCR) in soils collected from the Wind River and H.J. Andrews Experimental Forests. We compared these calibrations with equations suggested by manufacturers or commonly used in the literature and found the standard equations predicted soil moisture content 0%11.5% lower (p < 0.0001) than new calibrations. Each new calibration equation adequately predicted soil moisture from the output for each instrument regardless of location or soil type. Prediction intervals varied, with errors of 4.5%, 3.5%, and 7.1% for the ECH2O, CT, and WCR, respectively. Only the ECH2O system was significantly influenced by temperature for the range sampled: as temperature increased by 1 °C, the soil moisture estimate decreased by 0.1%. Overall, the ECH2O performed nearly as well as the CT, and thanks to its lower cost, small differences in performance might be offset by deployment of a greater number of probes in field sampling. Despite its higher cost, the WCR did not perform as well as the other two systems.
Using 13C nuclear magnetic resonance spectroscopy for the study of northern hardwood tissues
Authors: Johnson Chris E , Smernik Ronald J , Siccama Thomas G , Kiemle David K , Xu Zhihong , Vogt Daniel J
Published: October 2005

Nuclear magnetic resonance (NMR) spectroscopy is a useful tool for examining the structural chemistry of natural organic matter. The use of cross-polarization and magic-angle spinning to study 13C functionality (CPMAS 13C NMR) is convenient, but not always quantitative. We used various 13C NMR techniques to examine the structural chemistry of bark and wood of sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Ehrh.), and yellow birch (Betula alleghaniensis Britt.). Spin counting experiments showed that 87%97% of the 13C in the samples was observable by CPMAS 13C NMR. A comparison of CPMAS and Bloch decay experiments revealed few differences in spectral properties. Together, these results suggest that CPMAS 13C NMR is quantitative for these tissues. We observed little variation in the structural chemistry of wood, either among samples of the same species or among species. Within-species variations in bark chemistry were greater than in wood, probably because of variations in environmental conditions. However, we observed no significant differences in bark chemistry among the species. Bark and wood chemistry differed significantly, with the bark spectra displaying greater contributions from lignin, suberin, waxes, and resins. Hardwood spectra differ from softwood spectra in the aromatic C regions because of the contribution of syringyl units to hardwood lignin. Hardwood bark appears to contain less tannins than softwood bark. Together, the quantitative and qualitative features of CPMAS 13C NMR spectra are useful for studying the ecology of living and detrital wood and bark.
Effects of post-thinning density and repeated fertilization on the growth and development of young lodgepole pine
Authors: Brockley R P
Published: October 2005

The effects of factorial combinations of post-thinning density and fertilization on the growth and development of young lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) were investigated in central British Columbia. The effects of density and fertilization (repeated every 5 years) on tree height were small relative to the effects on stem radial growth. Tree radial growth increased with thinning intensity, whereas per-hectare growth was greatest at the highest residual density. Fertilizer effects varied across the range of residual densities tested. Tree and stand volume gains following fertilization were less, in both relative and absolute terms, at 600 trees/ha than at 1100 or 1600 trees/ha. Vigorous response of understory vegetation to nutrient additions (and strong competition for water and nutrients) may have reduced the effectiveness of fertilization on tree growth at 600 trees/ha relative to higher stand densities. Results indicate that the combined positive effects of thinning and fertilization on the growth of young lodgepole pine will accelerate stand development, thereby shortening technical rotation length. Results also indicate that significant growth gains following fertilization of thinned lodgepole pine will partially compensate for stand volume losses due to thinning. However, fertilization may be less effective at low stand densities, where negative effects of thinning on harvest volume are greatest.
Wetland drying and succession across the Kenai Peninsula Lowlands, south-central Alaska
Authors: Klein Eric , Berg Edward E , Dial Roman
Published: October 2005

This study documents the scale and intensity of drying over the last half century in the Kenai Lowlands of south-central Alaska. Using historical aerial photos and field sampling of wetlands, including muskegs, kettle ponds, and closed and open basin lakes, we present data on drying and successional changes in woody vegetation between 1950 and 1996. The results of this study suggest that the Kenai Peninsula is becoming both woodier in its vegetation and drier. A regional analysis of 1113 random points indicated increased forest cover and decreased open and wet areas in both burned and unburned areas between 1950 and 1996. A census of water bodies in three subregions indicates that almost two-thirds of water bodies visited show some level of decrease in spatial area. Over 80% of field sites visited have experienced some level of drying, where vegetation transects indicate substantial invasion into former lake beds by facultative upland plants. These results are consistent with a regional change in climate that is both warming and drying as documented in Kenai and Anchorage weather records.
Evaluating the effect of precommercial thinning on the resistance of balsam fir to windthrow through experimentation, modelling, and development of simple indices
Authors: Achim A , Ruel J -C , Gardiner B A
Published: October 2005

A tree-pulling experiment was carried out in stands of balsam fir (Abies balsamea (L.) Mill.) to evaluate the effects of early thinning on windthrow resistance. Forty trees from four stands were pulled over. Two stands had received a precommercial thinning 9 and 14 years previously, respectively, and the two others were unthinned controls. There were no significant inter-stand differences in the relationship between the critical turning moments required to overturn or snap the trees and their stem mass. The results were input into a model calculating critical wind speeds using the approach developed for the ForestGALES model. Simulations were run for four different stand densities. The mensurational characteristics for each run were taken from the results of a spacing trial established in balsam fir stands at Green River, New Brunswick. For stem breakage, the model predicted a gradual increase in critical wind speeds with wider spacing. The increase was smaller for tree overturning. The pattern of differences remained very similar after a simulated commercial thinning removing 30% of the basal area. Reductions in critical wind speeds were on the order of 4 m·s1 in all cases. Simple indices were developed that could estimate the relative results given by the model.
Seasonal differences in freezing tolerance of yellow-cedar and western hemlock trees at a site affected by yellow-cedar decline
Authors: Schaberg Paul G , Hennon Paul E , D'Amore David V , Hawley Gary J , Borer Catherine H
Published: October 2005

To assess whether inadequate cold hardiness could be a contributor to yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) decline, we measured the freezing tolerance of foliage from yellow-cedar trees in closed-canopy (nondeclining) and open-canopy (declining at elevations below 130 m) stands at three sites along an elevational gradient in the heart of the decline in southeastern Alaska. Foliar freezing tolerance was also assessed for sympatric nondeclining western hemlock (Tsuga heterophylla (Raf.) Sarg.). Measurements were made in the fall, winter, and spring to evaluate if seasonal differences in cold hardiness help explain species-specific injury. Significant differences in freezing tolerance attributable to site, canopy closure, species, and the interaction of canopy closure and species were each detected for at least one sample period. However, only two results were consistent with field reports of yellow-cedar decline: (1) between winter and spring measurements, yellow-cedar trees dehardened almost 13 °C more than western hemlock trees, so that yellow-cedar trees were more vulnerable to foliar freezing injury in spring than western hemlock; and (2) stands below 130 m appeared more vulnerable to freezing injury than stands above 130 m.
Efficiency of early selection for rotation-aged growth and wood density traits in Pinus radiata
Authors: Li Li , Wu Harry X
Published: October 2005

A total of 1097 cross-sectional wood disks from breast height were sampled from two rotation-aged (27 and 31 years from planting) genetic trials of radiata pine (Pinus radiata D. Don) in Australia to estimate the genetic correlation between early and rotation-aged growth and wood quality traits and the efficiency of early selection. Annual growth-ring width and density, diameter at breast height (DBH), and area-weighted density (AD) from 30 open-pollinated families were measured using X-ray densitometry. Genotype × site interactions were not significant for density and growth traits. Ring density increased steadily from the pith to cambial age 14, and then density had little change in the following years. For AD, the family and individual heritability estimates were about 0.60 and 0.30 after the first 2 years. For DBH, family and individual narrow-sense heritability estimates increased steadily after the first 4 years, and family heritability increased to 0.7 at a cambial age of 11 and had little change thereafter. Individual heritability estimate increased to 0.4 at cambial age 14 and was similar for the later ages. Beyond a cambial age of 5 years, there were strong negative genetic correlations of around 0.80 between AD and DBH. Ageage genetic correlations for AD were high and reached 0.80 and above after cambial age 3. Ageage genetic correlations for DBH were similar to AD, except the first two years. The most efficient early selection year was between ages 4 and 6 years after planting for AD, and between ages 8 and 11 years for DBH.