bluuebunny/crossref_metadata_2025 huggingface dataset:
Dorsal-fin spine growth of Heterodontus portusjacksoni: a general model that applies to dorsal-fin spines of chondrichthyans?
Authors: Tovar-Ávila Javier , Izzo Christopher , Walker Terence I , Braccini J Matias , Day Robert W
Published: March 2008

A prospective model of dorsal-fin spine growth in chondrichthyans is devised by studying the growth of spines from captive and wild Heterodontus portusjacksoni injected with several fluorochromes. Evidence was found for only two dentine layers in the spine trunk of H. portusjacksoni, contrasting with conjectures about the presence of a third middle dentine layer in some squalids. The spines have three simultaneous growth zones. The first growth zone is along the internal edge of the inner trunk dentine layer, where growth bands are deposited towards the centre (centripetally), increasing spine length and width by pressure against the cartilage rod. The second growth zone is along the external edge of the outer trunk dentine layer at the spine base, where growth bands are deposited in an opposite direction to the centre (centrifugally), increasing spine width. A third growth zone at the base of the cap enables downward expansion over the trunk. The model of concentric cones describes correctly the inner dentine layer growth pattern, whereas the outer dentine layer growth increments appear to be related to the external bands on the surface of the trunk. Growth increments from the three growth zones of the spine are all potentially useful for age estimation.
Phytoplankton species turnover controlled by physical forcing at different time scales
Authors: Pannard Alexandrine , Bormans Myriam , Lagadeuc Yvan
Published: March 2008

Changes in the physical and chemical environment induced by forcing events such as wind and rain can control the short-term dynamics of the phytoplankton community of inland waters. In two temperate reservoirs, species composition, diversity index, and species dynamics were characterized over periods of 3 weeks during different seasons, in parallel with changes in the physical and chemical structure of the water column. Dominant species and diversity index were shown to be controlled by environmental factors fluctuating on a seasonal and weekly time scale, whereas some rarer species responded to wind events and were indicators of a very short-term environmental change. As a consequence of the response of indicator species, the rate of change in species composition increased following meteorological events. Shifts in species composition were observed during each sampling period, except during the strongest stratification period. The shifts were associated with a modification of resource availability or intensity of stratification. We found that the resistance of the phytoplankton community to short-term physical forcing by wind increased with intensity of stratification. After the forcing event, the community did not return to its original structure because of modifications of the physical and chemical conditions induced by meteorological forcing on a weekly time scale.
Management inferences from a demographic analysis of sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes
Authors: Vélez-Espino Luis Antonio , McLaughlin Robert L , Pratt Thomas C
Published: March 2008

We use matrix models incorporating uncertainty in values of life history traits and density-dependent survival to assess pest management strategies implemented by the Great Lakes Fishery Commission to control nonnative sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes. The primary method of sea lamprey control has been treatment of rearing tributaries with chemical lampricides, but release of sterilized males and deployment of migratory barriers and traps are important components of the management plan. Uncertainties in the effectiveness of alternative control remain, however. Our models demonstrated that the management target of reducing lampricide use by 20% while maintaining current levels of control could be achieved if alternative methods are used to suppress current lake-wide fecundity rates by 49%–65%, assuming equal lampricide efficiency on larvae and metamorphosing individuals, or by 42%–55% when lampricide mortality on larvae is assumed to be half of that on metamorphosing individuals. At current levels of lampricide use, reduction to 72%–88% of current fecundity rates is recommended to ensure long-term control of sea lamprey populations in the face of uncertainty in current estimates of population growth rates. New control options targeting additional vital rates, such as survival of the parasitic life stage, could further reduce reliance on lampricides while maintaining effective sea lamprey control.
Retrospective analysis of harvest management performance for Bristol Bay and Fraser River sockeye salmon (Oncorhynchus nerka)
Authors: Martell Steven J.D. , Walters Carl J , Hilborn Ray
Published: March 2008

Given current knowledge of mean stock–recruitment relationships and variation in past recruitment, yield of sockeye salmon (Oncorhynchus nerka) in Bristol Bay, Alaska, and Fraser River, British Columbia, might have been at least 100%–300% larger since 1950 than was actually achieved. Most of these gains would have been due to knowledge of optimum mean spawning stock size rather than specific recruitment anomalies; knowing all future recruitment anomalies at the time of each spawning stock choice would have likely only added 2%–5% to total catches. For some stocks, delayed density dependence (cyclic dominance) might have resulted in somewhat lower yields, but under optimal management would still have been higher than were achieved. Even given only estimates of optimum spawning stock size each year based on data available as of that year, but following fixed escapement harvest policy rules, managers could likely have achieved 30%–40% higher total yield. Key management experiments for the future will involve testing for cyclic dominance effects on two major stocks (Kvichak, Late Shuswap) to determine whether stocks with strong, delayed, density-dependent survival effects should be deliberately managed through fallow rotation strategies for juvenile nursery lakes.
A temporally stable spatial pattern in the spawner density of a freshwater fish: evidence for an ideal despotic distribution
Authors: Purchase Craig F , Hutchings Jeffrey A
Published: March 2008

We explore the causal basis for a temporally stable spatial pattern in the density of spawning individuals of a freshwater fish. Based on a comparatively long-term set of data spanning one decade, reproductively active brook trout (Salvelinus fontinalis) inhabiting a near-pristine river on Cape Race, southeastern Newfoundland, occupy areas of either high or low density. Compared with their low-density counterparts, high-density aggregations are typically more than 30 times denser despite occupying only 4% of the available habitat. High-density areas are characterized by slower flow and suspected groundwater or bog-water seepage, attributes likely to increase the probability of offspring survival in Freshwater River. Disparity in density between high- and low-density aggregations declined as total population size increased, a pattern consistent with the predictions of the ideal free distribution. The larger body sizes of trout in the high-density aggregations may prevent others from occupying the most preferred spawning habitat. This spatial pattern in spawner density is consistent with that predicted by an ideal despotic distribution, although we cannot discount the influence that Allee effects might have on the distributional patterns of spawning individuals at low population sizes.
Streams modified for drainage provide fish habitat in agricultural areas
Authors: Stammler Katie L , McLaughlin Robert L , Mandrak Nicholas E
Published: March 2008

Open agricultural drains (ditches) provide necessary drainage for cropland and may also provide habitat supporting native fish assemblages. We tested whether warm-water drains in southwestern Ontario provide fish habitat similar to that of reference watercourses not subjected to drain maintenance. Features of fish assemblages and habitats were characterized using standardized protocols in 24 pairs of drains and reference watercourses. Drains and reference watercourses did not differ significantly in fish species richness, evenness, abundance, biomass, species composition, life stages, or nine of 13 physical habitat attributes expected to be altered by drain maintenance. These findings do not support concerns that drain maintenance has strong, lasting effects on fish assemblages and physical habitat features. Other landscape-level agricultural impacts may affect both drains and reference watercourses but were not examined in this study. We recommend that drains continue to be recognized as fish habitat under the Canadian Fisheries Act and that drain and fish habitat managers strive for logical, scientifically defensible drain maintenance practices that preserve fish biodiversity and habitat, while considering the needs of agriculture.
Groundwater balance in the wet zone of the USSR
Authors: Zaltsberg E.
Published: March 2008

Investigations of infiltration to the groundwater table and evaporation from it were carried out in the territory of the wet zone of the USSR during the 1970's. Relationships between infiltration, evaporation, and depth to the groundwater table were obtained. It was found that average means of these values decrease as the depth to the groundwater table increases in peat, fine sand, sandy loam, till, and varved loam. These relationships can be used for the approximate evaluation of groundwater balance in basins which have not yet been investigated. Keywords: groundwater table, balance, infiltration, evaporation.
Stability of the Fraser River Delta front
Authors: Luternauer J. L. , Finn W. D. Liam
Published: March 2008

The distributary front deposits of the delta consist mainly of interlayered sand and silt and lie in one of the most seismically active zones in Canada. Subsurface deposits at the north tend to be siltier than those at the south. Sediments on the surface of the delta slope range from clayey silts at the north to pure sands at the south. Slope angles vary from 23° at the head of the slope to 1–2° within 2 km beyond the tidal flats.Hydraulic bedforms observed on the sandy slopes southeast of the main channel gradually increase in size from small ripples to large asymmetric sand waves 2–3 m high and approximately 30 m long. They are generated primarily by flood tidal currents which scour the seabed to a water depth in excess of 100 m.Formation of gullies which crease the delta slope probably is initiated principally by failure of oversteepened deposits at a channel mouth. Previous studies have suggested that the large hummocks or ridges at the base of the slope off the Main Channel have been formed by the compressional folding of failed deposits. Recent reflection seismic surveys suggest that such a process has recurred in this area during the growth of the delta.Interpretation of SPT data, in the light of recent research findings, suggests that previous analyses have overestimated failure potential. It is estimated that the slope may withstand an earthquake with a duration corresponding to approximately 15 significant cycles of motion and a peak acceleration in the range of 11–13% G. Keywords: stability, Fraser River Delta front, mass wasting, erosion, liquefaction potential, cyclic mobility.
Effects of pile material and loading state on adhesive strength of piles in ice
Authors: Frederking R. , Karri J.
Published: March 2008

Laboratory tests on piles made of different materials (polyethylene, polyvinylchloride, steel, wood, concrete, and Inerta 160-coated steel) were used to investigate their adhesion to an ice cover at high rates of loading. Steel, wood, and concrete piles had adhesive strengths from 0.4 to 0.5 MPa; failure at these stresses occurred in the ice. Polyethylene and polyvinylchloride piles had an adhesive strength in the range 0.05–0.07 MPa; failure was characterized by separation between the pile and the ice. Inerta 160-coated steel had an intermediate strength of 0.25 MPa. Measured strengths were related both to the adhesion of ice to the pile and compliance of the pile. A special test series investigated the effect on adhesion of a tensile or compressive stress state in a polyethylene pile. An adhesive strength of 0.06 MPa was recorded in tension, and 0.13 MPa in compression, because of the relative stiffness of the pile and the ice. Keywords: ice loading, piles, ice adhesion, pile material, stress states.
Propriétés caractéristiques des argiles de l'est du Canada
Authors: Leroueil Serge , Tavenas François , Bihan Jean-Pierre Le
Published: March 2008

The compilation of numerous geotechnical data has allowed the definition of the main physical, mechanical, and hydraulic properties of marine and lacustrine clays of eastern Canada, as well as the establishment of correlations between some of these properties. The possible uses of these correlations are described.This study shows that the clays of eastern Canada exhibit a behaviour similar to that of other clays, but that they are characterized by a higher degree of structuration. Keywords: physical properties, mechanical properties, hydraulic properties, clays, Canada, correlations. [Journal translation]
Effect of particle size and strain conditions on the strength of crushed basalt
Authors: Al-Hussaini Mosaid
Published: March 2008

This paper describes the results of an investigation carried out to study the influence of particle size, stress level, density, method of consolidation, and strain conditions on the strength and compressibility of crushed basalt. All specimens were prepared at medium or high density, consolidated isotropically or under K0 consolidation, and sheared under effective confining pressure ranging from 443 to 2297 kPa. The material used in the test program had a straight line grain size distribution with maximum particle size ranges from 0.63 to 76.2 mm and minimum particle size equivalent to No. 30 U.S. standard sieve size:The tests indicated that an increase in the particle size (i.e., gradation) increases the strength and decreases the axial and the volumetric strain at failure. The study indicated further that the crushed basalt under triaxial compression has a lower shear strength than when sheared under plane strain conditions. Particles crushed were significantly influenced by the stress level and gradation and to a lesser degree by density of material. Keywords: cohesionless soils, density (mass/volume), shear tests, stress–strain diagram, compression tests, rockfill dams.
Preconsolidation pressure of Champlain clays. Part I. In-situ determination
Authors: Morin P. , Leroueil S. , Samson L.
Published: March 2008

The preconsolidation pressure of sensitive clays is an important parameter for the design of foundations on these soils, which are widespread in Eastern Canada and above all in the St. Lawrence and Ottawa Valleys where Champlain clays are found. A research study was initiated in 1979 to assess whether the preconsolidation pressure values derived from laboratory tests are representative of the preconsolidation pressure effectively mobilized in situ.Several existing structures were investigated and five of them are presented with performance records taken during and after construction together with data obtained from recent soil investigations. For each case study, the in-situ preconsolidation pressure is determined from the analysis of settlement and/or pore pressure records.The preconsolidation pressure values derived from conventional oedometer tests on good quality undisturbed samples are compared with the in-situ values and a simple correlation taking into account the overconsolidation ratio of the clay is proposed. Keywords: preconsolidation pressure, in-situ, laboratory, Champlain sea clays.
An apparatus for investigating earthquake-induced liquefaction experimentally
Authors: Morris Derek V.
Published: March 2008

An apparatus is described that simulates earthquake-induced liquefaction experimentally in a geotechnical centrifuge. Instrumentation allows dynamic motion and cyclically generated pore pressures to be measured. Modelling laws allow measurements to be related directly to an equivalent full-scale prototype, and a pilot test is described. Keywords: liquefaction, earthquakes, soil dynamics, shaking table, centrifuge.
Ultimate capacity of rigid single piles under inclined loads in sand
Authors: Chari T. R. , Meyerhof G. G.
Published: March 2008

The analysis and computation of the bearing capacity of rigid piles under inclined loads is usually based on a simplified pressure distribution along the pile length. Test data of actual pressures on such piles are scarce. Experiments were conducted with an instrumented 75 mm rigid circular pile embedded in homogeneous sand. The ultimate capacity of the pile was experimentally determined for different loading conditions and compared with analyses and test data reported previously. The interaction relationship of the load inclination on the ultimate capacity was obtained in the form of a polar diagram. Keywords: piles, lateral loads, cohesionless soils.
Distribution coefficients for strontium and cesium in overburden at a storage area for low-level radioactive waste
Authors: Johnston H. M. , Gillham R. W. , Cherry J. A.
Published: March 2008

Distribution coefficients for strontium and cesium, as one component of a hydrogeological site investigation, were determined by the batch method on 12 samples of glacial till and 7 samples of sand from the radioactive waste operations site 2 of the Bruce Nuclear Power Development. The tests were performed using two types of equilibrating solutions traced with radioisotopes; one was a solution with cation concentrations equal to the concentrations obtained in 1:1 solid–solution extracts and the other was natural groundwater obtained from piezometers at or near the depths from which the soil samples were obtained. The measured Kd values were relatively uniform within an individual hydrogeological unit, and differences between units were related to the chemical properties of both the solid and solution phases. The Kd values for both Sr and Cs obtained in the tests performed using the synthetic solutions differed from those obtained in tests using natural groundwater. The differences appeared to be related to the major chemistry of the test solutions and indicated that, to obtain Kd values that were most representative of the in situ conditions, natural groundwater should be used in the batch procedure.The measured Kd values, when used in the linear retardation equation, indicated that in the till materials, 90Sr would migrate at a rate no greater than 0.2 cm∙year−1 and 137Cs would migrate at a rate no greater than 0.001 cm∙year−1. Based on the relatively high Kd value for Cs in the sand (300 mL∙g−1), 137Cs migration through the sand unit would be of little environmental concern. On the other hand, the relatively low Kd for Sr (2 mL∙g−1) indicates that attention should be paid to the pathway role of the sand layer in any assessment of the isolation capability of the site.
Methanolysis of organophosphorus esters promoted by an M2+ catalyst supported on polystyrene-based copolymers
Authors: Didier Benoit , Mohamed Mark F , Csaszar Elizabeth , Colizza Kate G , Neverov Alexei A , Brown R Stan
Published: March 2008

The methanolysis of three neutral organophosphorus esters (a phosphonate, a phosphonothioate, and a phosphorothionate) promoted by several polymer-supported Zn(II) or Cu(II) containing catalysts was studied. The catalysts consist of a Zn(II) or Cu(II) complex with 1,5,9-triazacyclododecane or phenanthroline attached to a porous polystyrene resin. In each case, the polymer supported catalyst showed activity at near neutral sspH in methanol (8.38) and ambient temperature and provided accelerations of up to a factor of 2.9 × 106 relative to the background reaction at sspH 9.05. The solid materials could be reused several times and could be reactivated when the activity diminished. Various polymers of different porosity and extent of cross-linking were studied, with the net result being that larger porosities offer the best reactivity for catalyzed methanolysis of these OP species in methanol. This is explained by different parameters including the accessibility to reactive sites, the increase of concentration of catalytic sites on the surface of the polymer, and some cooperative effects between neighboring catalytic groups.Key words: functionalized polymer, metal containing, methanolysis, organophosphorus pesticides and CW agents, catalyst.
Chemistry of photogenerated α-phenyl-substituted o-, m-, and p-quinone methides from phenol derivatives in aqueous solution
Authors: Diao Li , Wan Peter
Published: March 2008

The enhanced photochemical reactivity of o-substituted phenols in its propensity to give o-quinone methide (o-QM) intermediates via excited state intramolecular proton transfer (ESIPT) was uncovered by Keith Yates as part of his now classic studies of photohydration of aromatic alkenes, alkynes, and related compounds. Photogeneration of QMs and the study of their chemistry along with potential biological applications are the focus of many groups. In this work, photochemical precursors to o-, m-, and p-QMs based on substituted phenols (hydroxybenzyl alcohols) and related compounds have been studied in aqueous solution as a function of pH and water content. The focus will be on QMs that are stabilized by an α-phenyl substituent, which enhances quantum yields for their formation, with the resulting QMs having longer lifetimes and easier to detect. Noteworthy is that all QM isomers can be photogenerated with the o and m isomers being the most efficient, consistent with the Zimmerman “ortho-meta” effect. m-QMs have formal non-Kekulé structures, and although they can be routinely photogenerated, are found to be most reactive. One m-QM was found to undergo a photocondensation reaction at high pH giving rise to m-substituted oligomers. The mechanism of QM formation in aqueous solution is believed to involve singlet excited phenols that undergo adiabatic deprotonation to give the corresponding photoexcited phenolate ion, which subsequently expels the hydroxide ion (photodehydroxylation). A pathway involving direct loss of water for the o-isomers is also possible in organic solvents.Key words: quinone methides, phenols, excited state acidity, solvolysis, carbocations, meta effect, photopolymerization, non-Kekulé intermediates.
Synthesis of 2,4,5-trisubstituted imidazoles catalyzed by [Hmim]HSO4 as a powerful Brönsted acidic ionic liquid
Authors: Khosropour Ahmad R
Published: March 2008

An efficient and green procedure for the synthesis of 2,4,5-trisubstituted imidazoles with various aldehydes using a catalytic amount of 1-methylimidazolium hydrogenesulfate as an active and low cost Brönsted acidic room temperature ionic liquid has been developed. The ionic liquid was easily separated from the reaction mixture and was recycled five times without any loss in activity.Key words: ionic liquid, 2,4,5-trisubstituted imidazoles, [Hmim]HSO4, aldehyde, benzil.
Carbanion reactivity — σ-adduct formation and elimination in the reactions of the carbanion from bis(phenylsulfonyl)methane with 4-nitrobenzofurazan derivatives
Authors: Asghar Basim H.M. , Crampton Michael R , Isanbor Chukwuemeka
Published: March 2008

1H NMR studies in [2H6]-DMSO show that the carbanion 4 from bis(phenylsulfonyl)methane reacts with 4,6-dinitrobenzofuroxan to yield a σ-adduct that undergoes base-catalysed elimination to yield an alkene derivative. Rate constants, measured spectrophotometrically, are reported for the corresponding reactions in methanol of 4 with 4-nitrobenzofurazan and some derivatives that give adducts at the 5-position. The intrinsic rate constant, ko, for this process has a value of 1.5 ± 0.5. The 5-adducts undergo methoxide-catalysed elimination of phenylsulfinic acid to yield alkene derivatives and rate constants for this process are reported.Key words: carbanions, 4-nitrobenzofurazan, σ-adducts, elimination reactions.
Synthesis and tautomerization study of pseudonitrosites to 1,2-nitroximes
Authors: Shaabani Ahmad , Bijanzadeh Hamid Reza , Karimi Ali Reza , Teimouri Mohammad Bagher , Soleimani Kamal
Published: March 2008

4-R-Substituted 2-nitro-1-nitrosoethylbenzenes (R = H, CH3, OCH3, Cl, F) have been synthesized under solvent-free conditions and the mechanism of their tautomerization to 2-isonitroso-1-nitro-2-phenylethanes have been investigated by 1H NMR spectroscopy.Key words: tautomerization, pseudonitrosite, mechanism, 2-nitro-1-nitrosoethylbenzene, 1H NMR spectroscopy
Multiscale modeling of longleaf pine (Pinus palustris)
Authors: Loudermilk E. Louise , Cropper Wendell P.
Published: March 2008

There are few remaining longleaf pine ( Pinus palustris Mill.) ecosystems left in the southeastern coastal plain of the United States. Restoration and maintenance of these remaining habitats requires an understanding of ecosystem processes at multiple scales. The focus of this study was to develop and evaluate a modeling framework for analyzing longleaf pine dynamics at the spatially explicit landscape scale and at the spatially implicit population scale. The landscape disturbance and succession (LANDIS) model was used to simulate landscape fire dynamics in a managed forest in north-central Florida. We constructed a density-dependent longleaf pine population matrix model using data from a variety of studies across the southeastern United States to extend an existing model. Sensitivity analyses showed that the most sensitive parameters were those from the original pine model, which was based on extensive observations of individual trees. A hybrid approach integrated the two models: the fire frequencies output from the LANDIS model were input to the matrix model for specific longleaf pine populations. These simulations indicated that small isolated longleaf pine populations are more vulnerable to fire suppression and that landscape connectivity is a critical concern. A frequent prescribed fire regime is nonetheless necessary to maintain even large longleaf pine sandhill communities that have better landscape connectivity.
The use of cellular automaton approach in forest planning
Authors: Heinonen Tero , Pukkala Timo
Published: March 2008

This study presents an optimization method based on cellular automaton (CA) for solving spatial forest planning problems. The CA maximizes stand-level and neighbourhood objectives locally, i.e., separately for different stands or raster cells. Global objectives are dealt with by adding a global part to the objective function and gradually increasing its weight until the global targets are met to a required degree. The method was tested in an area that consisted of 2500 (50 × 50) hexagons 1 ha in size. The CA was used with both parallel and sequential state-updating rules. The method was compared with linear programming (LP) in four nonspatial forest planning problems where net present value (NPV) was maximized subject to harvest constraints. The CA solutions were within 99.6% of the LP solutions in three problems and 97.9% in the fourth problem. The CA was compared with simulated annealing (SA) in three spatial problems where a multiobjective utility function was maximized subject to periodical harvest and ending volume constraints. The nonspatial goal was the NPV and the spatial goals were old forest and cutting area aggregation as well as dispersion of regeneration cuttings. The CA produced higher objective function values than SA in all problems. Especially, the spatial objective variables were better in the CA solutions, whereas differences in NPV were small. There were no major differences in the performance of the parallel and sequential cell state-updating modes of the CA.
Carbon storage in a chronosequence of red spruce (Picea rubens) forests in central Nova Scotia, Canada
Authors: Taylor Anthony R. , Wang Jian R. , Chen Han Y.H.
Published: March 2008

Red spruce ( Picea rubens Sarg.) forests are an ecologically and economically important forest type in eastern Canada. We quantified the carbon (C) stocks of natural red spruce dominated stands in central Nova Scotia. Twenty-four stands over a 140 year chronosequence were sampled. Within each stand, major C pools including above- and below-ground tree biomass, shrub and herb vegetation, dead organic matter, and upper (0–10 cm) mineral soil were measured. A nonlinear four-parameter logistic function was fitted to the total site C stock data to describe the change in total ecosystem C storage over time. Total site C storage increased throughout stand development in a general sigmoidal pattern, increasing from 94.4 Mg C·ha–1in the youngest age-class to a maximum of 247.0 Mg C·ha–1in the 81- to 100-year-old age-class, then decreasing in the oldest age-classes. Carbon pools of live vegetation, standing dead trees, and downed woody debris displayed recognizable changes in C storage throughout stand development, conforming to some of the fundamental ideas on forest stand dynamics. Overall, above- and below-ground tree biomass had the greatest influence on total site C storage dynamics. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate carbon stocks at the regional scale.
Effects of timber harvest on carbon pools in Ozark forests
Authors: Li Qinglin , Chen Jiquan , Moorhead Daryl L. , DeForest Jared L. , Jensen Randy , Henderson Rachel
Published: March 2008

We quantified and compared carbon (C) pools at a Missouri Ozark experimental forest 8 years after different harvest treatments. Total C pools were 182, 170, and 130 Mg C·ha–1for the control (no-harvest management; NHM), single-tree, uneven-age management (UAM), and clearcut even-age management (EAM) stands, respectively. Harvesting reduced the live tree C pool by 31% in the UAM, 93% in EAM stands, and increased the coarse woody debris (CWD) C pool by 50% in UAM and 176% for EAM, compared with NHM stands. UAM significantly (p = 0.02) increased the mineral soil C pool by 14%, whereas EAM had no effect. More interestingly, the distribution of C among various components (i.e., live, dead wood, CWD, litter, and soil) ranged from 0.7% to 29% on NHM stands and from 0.1% to 43% on EAM stands. Soil nitrogen (N) (%) was significantly correlated with soil C (%) in the UAM stands, whereas soil temperature was negatively related to live tree C. Soil N (%) and canopy cover were significantly correlated with live tree and soil C (%) pools at EAM stands. Our results revealed that the largest C pool in these forests was living trees. The soil and CWD C pool sizes suggest the importance of dynamics of decaying harvest debris, which influences N retention.
Spatial model of site index based on γ-ray spectrometry and a digital elevation model for two Pinus species in Tuan Toolara State Forest, Queensland, Australia
Authors: Wang Qing , Preda Micaela , Cox Malcolm , Bubb Ken
Published: March 2008

Site index prediction models are an important aid for forest management and planning activities. This paper introduces a multiple regression model for spatially mapping and comparing site indices for two Pinus species ( Pinus elliottii Engelm. and Queensland hybrid, a P. elliottii × Pinus caribaea Morelet hybrid) based on independent variables derived from two major sources: γ-ray spectrometry (potassium (K), thorium (Th), and uranium (U)) and a digital elevation model (elevation, slope, curvature, hillshade, flow accumulation, and distance to streams). In addition, interpolated rainfall was tested. Species were coded as a dichotomous dummy variable; interaction effects between species and the γ-ray spectrometric and geomorphologic variables were considered. The model explained up to 60% of the variance of site index and the standard error of estimate was 1.9 m. Uranium, elevation, distance to streams, thorium, and flow accumulation significantly correlate to the spatial variation of the site index of both species, and hillshade, curvature, elevation and slope accounted for the extra variability of one species over the other. The predicted site indices varied between 20.0 and 27.3 m for P. elliottii, and between 23.1 and 33.1 m for Queensland hybrid; the advantage of Queensland hybrid over P. elliottii ranged from 1.8 to 6.8 m, with the mean at 4.0 m. This compartment-based prediction and comparison study provides not only an overview of forest productivity of the whole plantation area studied but also a management tool at compartment scale.
Fire and substrate interact to control the northern range limit of black spruce (Picea mariana) in Alaska
Authors: Lloyd Andrea H. , Fastie Christopher L. , Eisen Hilary
Published: March 2008

Black spruce ( Picea mariana (Mill.) BSP) is a common treeline species in eastern Canada but rare at treeline in Alaska. We investigated fire and substrate effects on black spruce populations at six sites along a 74 km transect in the Brooks Range, Alaska. Our southern sites, on a surface deglaciated >50 000 years ago, had significantly more acidic soils, more black spruce, and higher seed viability than our northern sites, which were deglaciated approximately 13 000 years ago. Despite similar fire history at five of our six sites, postfire recruitment dynamics varied with surface age. Sexual reproduction was vigorous in both postfire and nonfire years in populations on the older surface. On the younger surface, vigorous sexual reproduction was restricted to postfire decades and clonal reproduction by branch layering predominated in nonfire years. At the northernmost site, which was unburned, black spruce reproduced almost exclusively by layering. The species’ northern range limit thus reflects an interaction between fire and substrate: on recently deglaciated surfaces, sexual reproduction is restricted to postfire years. This substrate-induced dependence on fire may restrict the range of black spruce to sites that burn sufficiently often to allow occasional sexual reproduction.
Fire potential rating for wildland fuelbeds using the Fuel Characteristic Classification SystemThis article is one of a selection of papers published in the Special Forum on the Fuel Characteristic Classification System.
Authors: Sandberg David V. , Riccardi Cynthia L. , Schaaf Mark D.
Published: March 2008

The Fuel Characteristic Classification System (FCCS) is a systematic catalog of inherent physical properties of wildland fuelbeds that allows land managers, policy makers, and scientists to build and calculate fuel characteristics with complete or incomplete information. The FCCS is equipped with a set of equations to calculate the potential of any real-world or simulated fuelbed to spread fire across the surface and in the crowns, and consume fuels. FCCS fire potentials are a set of relative values that rate the intrinsic physical capacity of a wildland fuelbed to release energy and to spread, crown, consume, and smolder under known or benchmark weather and fuel moisture conditions. The FCCS reports eight component fire potentials for every fuelbed, arranged in three categories: surface fire behaviour (reaction intensity, spread rate, and flame length), crown fire potential (torching and active crown fire), and available fuel potential (flaming, smouldering, and residual smouldering). FCCS fire potentials may be used to classify or compare fuelbeds that differ because of location, structure, passage of time, or management action, based on expected fire behavior or effect outcomes. As a classification tool, they are offered as an objective alternative to categorizing bulk properties of fuelbeds or stylized model inputs.
Modeling stability and resilience after slashburning across a sub-boreal to subalpine forest gradient in British Columbia
Authors: Hamilton Evelyn H. , Haeussler Sybille
Published: March 2008

Stability and resilience of conifer-dominated vegetation communities following clear-cutting and slashburning in central British Columbia, were modeled across gradients of resource availability, fire return interval (FRI), and fire severity. We hypothesized that high resource availability and long fire-free intervals would enhance stability, whereas high resource availability and short fire-free intervals would confer resilience. Fire weather indices and pre- and post-burn fuel loads were recorded and vegetation regrowth monitored for 5–11 years at 12 sites. Stepwise regression was used to model rates of revegetation, increases in vascular species richness, and pre- and post-burn similarity of species composition as a function of the environmental variables. Predicted stability for four sub-boreal to subalpine vegetation communities with contrasting resource availability and FRI corresponded closely to our hypotheses. Rates of revegetation were more strongly correlated with resource availability, whereas composition-based response variables were more strongly correlated with the FRI. Based on revegetation rates, all ecosystems were predicted to have equal resilience. However, based on vegetation composition, mesic sub-boreal ecosystems were predicted to be more resilient than mesic subalpine ecosystems because the degree of change in species composition was less sensitive to increasing burn severity. More slashburned sites with a broader range of burn severities are needed to verify these preliminary models.
Structure and regeneration dynamics of three subtropical midmontane moist evergreen broad-leaved forests in southwestern China, with special reference to bamboo in the forest understories
Authors: Tang Cindy Q. , Li Tianxing , Zhu Xiaohong
Published: March 2008

Two midmontane moist evergreen broad-leaved forests on the Ailao Mountains, Yunnan, and one on Mount Emei, Sichuan, southwestern China were studied to characterize the forest structure and dynamics as manifested in size, age, canopy gaps, regeneration modes, and the survival of seedlings. The most dominant canopy trees were species of Lithocarpus and Castanopsis of Fagaceae along with species of Machilus of Lauraceae and of Schima of Theaceae. The vertical structures of the forests were multilayered. All the canopy species had multimodal-shaped size and age distributions. In each forest of the study sites, the mean size of a canopy gap, caused mainly by the death of canopy trees, was smaller than 65 m2. No surviving seedlings of Fagaceae species were found in understories having bamboo with a coverage greater than 25% in any quadrat of the three forests. The poor seedling bank in the study forests is apparently due to the presence of bamboo in the understory. The tree regeneration may be synchronously related to the bamboo flowering event (interval approximately 55–60 years).
A conceptual framework for ranking crown fire potential in wildland fuelbedsThis article is one of a selection of papers published in the Special Forum on the Fuel Characteristic Classification System.
Authors: Schaaf Mark D. , Sandberg David V. , Schreuder Maarten D. , Riccardi Cynthia L.
Published: March 2008

This paper presents a conceptual framework for ranking the crown fire potential of wildland fuelbeds with forest canopies. This approach extends the work by Van Wagner and Rothermel, and introduces several new physical concepts to the modeling of crown fire behaviour derived from the reformulated Rothermel surface fire modeling concepts proposed by Sandberg et al. (this issue). This framework forms the basis for calculating the crown fire potentials of Fuel Characteristic Classification System (FCCS) fuelbeds (Ottmar et al., this issue). Two new crown fire potentials are proposed (i) the torching potential (TP) and (ii) the active crown potential (AP). A systematic comparison of TP and AP against field observations and Crown Fire Initiation and Spread (CFIS) model outputs produced encouraging results, suggesting that the FCCS framework might be a useful tool for fire managers to consider when ranking the potential for crown fires or evaluating the relative behaviour of crown fires in forest canopies.
Height development of shade-tolerant conifer saplings in multiaged Acadian forest standsPublication 2954 of the Maine Agricultural and Forest Experiment Station, University of Maine, Orono, Maine.
Authors: Moores Andrew R. , Seymour Robert S. , Kenefic Laura S.
Published: March 2008

Understory growth dynamics of northern conifer species were studied in four stands managed under multiaged silvicultural systems in eastern Maine. Height growth of Picea rubens Sarg., Abies balsamea (L.) Mill., and Tsuga canadensis (L.) Carr. saplings between 0.5 and 6.0 m in height was related to the proportion open sky (POS), using sapling height as a covariate. Height growth of T. canadensis equaled A. balsamea and exceeded P. rubens under very low light levels (POS < 0.1) but is much less responsive to both increasing POS and taller heights, reaching 50% of its maximum height growth at a POS of only 0.09. Abies balsamea outgrew P. rubens under similar dark conditions; at higher light levels (POS > 0.10), both species grew similarly. Evidently, no feasible overstory manipulation of light alone can promote more rapid height development of P. rubens saplings over A. balsamea. A nonlinear light-prediction model using stand basal area is linked with height-growth prediction equations to quantify sapling development from 0.5 to 6 m. Depending on overstory density, P. rubens requires a height advantage of 0.14–0.33 m over a 0.5 m tall A. balsamea to reach a height of 6 m over the same time period.
Genetic control of propagation traits in a singleCorymbia torelliana×Corymbia variegatafamily
Authors: Shepherd Mervyn , Pomroy Peter , Dieters Mark , Lee David
Published: March 2008

Genetic control of vegetative propagation traits was described for a second-generation, outbred, intersectional hybrid family (N = 208) derived from two species, Corymbia torelliana (F. Muell.) K.D. Hill & L.A.S. Johnson and Corymbia variegata (F. Muell.) K.D. Hill & L.A.S. Johnson, which contrast for propagation characteristics and in their capacity to develop lignotubers. Large phenotypic variances were evident for rooting and most other propagation traits, with significant proportions attributable to differences between clones (broad-sense heritabilities 0.2–0.5). Bare root assessment of rooting rate and root quality parameters tended to have the highest heritabilities, whereas rooting percentage based on root emergence from pots and shoot production were intermediate. Root biomass and root initiation had the lowest heritabilities. Strong favourable genetic correlations were found between rooting percentage and root quality traits such as root biomass, volume, and length. Lignotuber development on a seedling was associated with low rooting and a tendency to poor root quality in cuttings and was in accord with the persistence of species parent types due to gametic phase disequilibrium. On average, nodal cuttings rooted more frequently and with higher quality root systems, but significant cutting type × genotype interaction indicated that for some clones, higher rooting rates were obtained from tips. Low germination, survival of seedlings, and rooting rates suggested strong hybrid breakdown in this family.
Estimation of coarse root biomass and nutrient content for sugar maple, jack pine, and black spruce using stem diameter at breast height
Authors: Ouimet Rock , Camiré Claude , Brazeau Marcel , Moore Jean-David
Published: March 2008

Estimates of belowground biomass and mineralomass are fundamental to understanding carbon and element cycling in forest ecosystems. At two sites, we measured coarse root (diameter ≥2 mm) biomass by diameter class and their mineralomass for sugar maple ( Acer saccharum Marsh.), black spruce ( Picea mariana (Mill.) BSP), and jack pine ( Pinus banksiana Lamb.) trees to relate them to stem diameter at breast height (DBH). All regressions describing coarse root biomass and nutrient content as a function of stem DBH were highly significant (r2 ≥ 0.89, P < 0.001). Root mineral element (N, P, K, Ca, Mg, and S) concentrations varied with tree species and root diameter class. Sugar maple roots had higher N, P, and S concentrations than the other two tree species. Black spruce had higher root Ca concentrations. Element concentrations increased consistently with the reduction of root diameter for the three studied species. We also found that the horizontal root extent of sugar maple was related to tree DBH. In conjunction with other studies, the relationship suggests that this tree species could tolerate a 10%–20% root loss but not losses ≥28%–34%; otherwise, sugar maple health and vigour would be compromised in the short term.
Assessing innovativeness in the North American softwood sawmilling industry using three methods
Authors: Knowles Chris , Hansen Eric , Shook Steven R.
Published: March 2008

Using a mail questionnaire targeted at 500 softwood sawmills in the United States and Canada, firm innovativeness was assessed using three methods: (1) current technology, (2) self-evaluation, and (3) a new scale — the propensity to create and adopt scale. The results of these three methods were then compared to assess the performance of each method. Additionally, the relationship between firm innovativeness and financial performance was examined. Based on responses from 85 sawmills (19% adjusted response rate), the results show that both the self-evaluated and the propensity to create and adopt measures differentiate between mills with high and low levels of innovativeness. The composite of the propensity to create and adopt scale shows higher reliability (Chronbach’s α = 0.97) than the self-evaluated scale (Chronbach’s α = 0.68). Significant relationships between sawmill performance and each of the three measures of innovativeness were seen, with the propensity to create and adopt scale generally having the strongest positive relationships. Current technology was significantly related to sales growth, but not gross profit.
Short-term changes in Pinus strobus sapling height/diameter ratios following partial release: testing the acclimative stem-form development hypothesis
Authors: Zenner Eric K.
Published: March 2008

Following release, mature trees can acclimatively shift aboveground growth allocation from height to diameter at breast height (DBH) growth to adjust their stem form (reducing height/diameter ratio (HDR)) to better withstand increased wind stress. The purpose of this study was to determine if, over a 6-year period, 7- to 12-year-old eastern white pines ( Pinus strobus L.) also responded to different levels of partial release with (i) stem-form adjustments (reduced HDR) through growth-allocation shifts from height to DBH growth and (ii) lower HDR values (shorter heights) than for unreleased trees of the same DBH (“acclimative stem-form development hypothesis”). Over the 6-year postrelease period, juvenile white pine seedlings exhibited unsynchronized height and DBH growth response patterns that depended on their prerelease height growth. Height growth of faster growing white pines was temporarily reduced. Concurrently, DBH growth was enhanced with increasing release intensity. HDR reductions followed a fairly narrow and predictable trajectory, but HDR values of released trees were not lower than those of unreleased trees of the same DBH after 6 years. Juvenile white pine seedlings appear to maintain a balance among aboveground tree parts to enhance future tree stability, which may be an adaptive trait for moderately shade-tolerant species.