bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential responses of growth, photosynthesis, respiration, and phosphate uptake to copper in copper-tolerant and copper-intolerant strains of Scenedesmus acutus (Chlorophyceae)
Authors: Nalewajko Czeslawa , Olaveson Mary M.
Published: February 2008

We detected significant differences in copper toxicity to growth and several physiological processes (e.g., photosynthesis, respiration, and phosphate uptake) in three strains of Scenedesmus acutus f. alternans demonstrating differential sensitivity to copper. The copper-intolerant strain (designated X-72) and the two copper-tolerant strains (designated X-Cu and B-4) were tested in long-term (5-day) growth bioassays and short-term (< 24 h) physiological experiments under both nutrient-sufficient and nutrient-limited conditions. The three strains showed the same pattern of sensitivity to copper for growth and for all physiological processes examined: the copper-intolerant strain, X-72, showed the greatest sensitivity, followed by X-Cu. B-4 was most tolerant. Under nutrient-sufficient conditions, growth was more sensitive to copper than photosynthesis or respiration. Depression of the growth rate to 50% of control occurred at 25, 56, and 175 nmol Cu/106 cells in X-72, X-Cu, and B-4, respectively. Photosynthesis and respiration were inhibited in cultures that were preexposed to algistatic copper dosages for 20 h prior to testing. Both processes were equally inhibited in X-72 (to about 8.5% of controls) and in X-Cu (to about 32% of controls), but respiration was more inhibited than photosynthesis in B-4 (to 47.7 vs. 67.1% of control rates). L-buthionine-S,R-sulfoximine (BSO), a known inhibitor of phytochelatin synthesis, significantly reduced the tolerance of photosynthesis to copper in X-72 but not in X-Cu or B-4. Short-term responses among several physiological processes were also examined under phosphorus and nitrogen limitation. In P-limited cultures, phosphate uptake was depressed by 50% at 3 nmol Cu/106 cells in X-72, and at 5.8 nmol Cu/106 cells in X-Cu and B-4. In N-limited cultures, photosynthesis was more tolerant to copper than in nutrient-sufficient conditions in both X-72 and X-Cu but less tolerant in B-4. Key words: copper toxicity, growth, nutrient limitation, nitrogen, phosphate uptake, photosynthesis, respiration, Scenedesmus.
Aggregating points to fit Pielou's index of nonrandomness
Authors: Stauffer Howard B.
Published: February 2008

New methods of simulating aggregated distribution of point spatial patterns have been developed. These methods aggregate points to a degree specified by Pielou's index of nonrandomness by reversing its sampling procedure. Included are a review of previous methods of simulating aggregation, a full description of the present approach, and examples of simulations with varying density levels.
Incidence and condition of vesicular–arbuscular mycorrhizae infections in the roots of sugar maple in relation to maple decline
Authors: Spitko Roberta A. , Tattar Terry A. , Rohde Richard A.
Published: February 2008

Twelve sugar maples (Acersaccharum Marsh.) on the campus of the University of Massachusetts were selected for the study in spring 1977. Trees chosen ranged from healthy to severely declined and were assigned to crown-condition classes of increasing severity from I to IV. Whole root samples from each tree were cleared in 10% KOH and stained in trypan blue to assess the degree of vesicular–arbuscular infection. Five sections of secondary feeder roots from each tree were selected at random and examined under a microscope. The number of infected cortical cells per centimetre of roots was counted to give an estimate of percent mycorrhizal infection for each tree. An inverse relationship was found between the degree of decline shown by the crown and the amount of mycorrhizal infection in the roots. Trees of class I had young infections showing extensive arbuscule development and few vesicles. In classes II to IV there was a decrease in the number of cortical cells infected by the fungus and an increase in vesicle formation, at times to the point where cortical cells were disrupted by their presence. In class IV, arbuscules that were present had undergone digestion of the fine branches so that only the collars were in evidence. Soil pH and nutritional status were determined but no relationship was found between these factors and the health of the fungal symbiont in the roots.
Snow accumulation and melt in small forest openings in Alberta
Authors: Golding D. L. , Swanson R. H.
Published: February 2008

A study was carried out from 1973 to 1976 to determine snow-trapping efficiency and ablation rates in circular openings of 1/4–6 tree heights (H) in diameter, spaced 10 H between centers. The greatest snow accumulation was in 2-H and 3-H openings, closely followed by 1-H and 3/4-H openings. Below 3/4 H, accumulation dropped off rapidly, with the minimum being in the uncut forest. Ablation rates (expressed as centimetres water equivalent per day) were least in the 1 H, followed closely by 3/4 H. Rates increased above and below 3/4 H and 1 H, with maximum rates in 5-H and 6-H openings.In 1977 and 1978 measurements were made in 14 closely spaced (2 H between centers) 1-H openings. Snow accumulation and ablation rate were the same as in the more widely spaced 1-H openings.
Barrier-zone formation in wounded stems of sweetgum
Authors: Moore Kathleen E.
Published: February 2008

The response of sweetgum trees (Liquidambarstyraciflua L.) to wounding was examined histologically. Seven stems were wounded artificially (by exposing the cambium or cutting deep into the xylem) or naturally (by fire or by frost cracks). After wounding, the cambium produced an anatomically distinct tissue which limited radial spread of discoloration and decay near the wounds. This tissue was characterized by traumatic gum canals, large amounts of longitudinal parenchyma, thin-walled fiber sclereids, callose deposits, staining of cell walls with phloroglucinol, and a weak or fading Maule reaction for lignin. This tissue extended no more than 60 cm longitudinally above and below the wounds and no more than 20 cm around the stem, less than 50% of the circumference of any tree. Gum canals and associated tissue were an effective barrier to the radial spread of discoloration and decay. Water-soluble extractives from the tissue of the annual ring formed after wounding inhibited growth of the decay fungus, Pleurotussapidus, invitro. This inhibition was not observed with extractives more than 20 cm longitudinally from the wound. These results indicate that the barrier zone formed by sweetgum in response to the stem wounds studied was limited to the vicinity of the wound and may be both an anatomical and chemical barrier. Thus, morphologically distinguishable barrier zones cannot alone account for protection of xylem formed after wounding from discoloration and decay.
Effects of increased spacing on carbon mineralization rates and temperature in a stand of young balsam fir
Authors: Piene Harald
Published: February 2008

Treatment to reduce density, from 19 000 stems/ha to about 1642 stems/ha at a regular spacing of 2.4 × 2.4 m, in a young balsam fir (Abiesbalsamea (L.) Mill.) stand stimulated carbon mineralization rates of the litter layer which were, in turn, positively correlated with inorganic nitrogen levels. Increased carbon mineralization rates were attributed to increased summer temperatures in the litter layer. Temperature measurements under the snow indicated a consistently lower winter temperature in the treated stand as compared with the control. The increased and more regular spacing in the treated stand resulted in more rapid basal area growth, increased needle weights, and greater foliar N concentrations, reflecting an increased nitrogen uptake by the trees.
Short-term influence of moose upon woody plants of an early seral wintering site in Gaspé Peninsula, Quebec
Authors: Bédard J. , Crête M. , Audy E.
Published: February 2008

Two 0.1-ha moose (Alcesalcesamericana Cl.) exclosures and two unfenced control blocks were established in an 8-year postlogging site used for winter foraging by moose. During the 5-year experiment, moose visited the two unfenced blocks each winter removing between 22 and 58 kg (dry weight) per hectare of browse. The shrub layer comprised little other than mountain maple (Acerspicatum Lam.), beaked hazelnut (Coryluscornuta Marsh.), and balsam fir (Abiesbalsamea (L.) Mill.). Stem density remained relatively constant in the exclosures while increasing markedly in the unfenced blocks with hazel stems increasing from 37 to 56% of all stems. Seedlings or sprouts of mountain maple decreased slightly in the exclosures while increasing rapidly in the unfenced blocks. Plant heights and diameters at ground level increased significantly in the exclosures. Available forage from maple and hazel increased more rapidly in the controls than in the ex-closures.We conclude that moose, even at relatively low wintering density, can exert a major role upon the physiognomy and the composition of seral shrub communities.
Sweet fern rust resistance in jack pine seedlings: geographic variation
Authors: Tauer Charles G.
Published: February 2008

Inoculation of Pinusbanksiana Lamb, seedlings from 47 provenance collections with basidiospores of Cronartiumcomptoniae Arth. from Cloquet, Minnesota, demonstrated the occurrence of resistance within the species. Percent infection obtained ranged from 100 for some Saskatchewan, Alberta, and Manitoba sources to 17 for a Michigan and an Ontario source. A band of resistance extending from southwestern Quebec to northeastern Wisconsin was delineated.
The potential of Weibull-type functions as flexible growth curves
Authors: Yang R. C. , Kozak A. , Smith J. H. G.
Published: February 2008

A new growth function, which is flexible enough in shape to accommodate most biological growth behavior, is created by adding an expanding factor to the Weibull distribution function. Many monotonically increasing biological growth phenomena can be excellently modelled by this function with various numerical values for the scale, the shape, and the upper asymptote parameters. The function is illustrated with height–age and volume–age curves for single trees and two polymorphic stand volume–age curves.
Community changes in a deciduous forest exposed to air pollution
Authors: McClenahen James R.
Published: February 2008

Vegetation was measured in seven stands on similar sites in a 50-km portion of the upper Ohio River Valley. These stands lay along gradients of chronic exposure to airborne chloride (Cl−), sulfur dioxide (SO2), fluorides (F−), and possibly other pollutants. Species richness, evenness, and Shannon diversity index were generally depressed within the overstory, subcanopy, and herb strata near industrial sources of air pollutants. A significant relationship between coefficient of community and combined air pollutant index (relative exposure of stands to Cl−, F−, and SO2) showed that similarity in species composition decreased along a gradient of increasing air pollutant exposure. Increasing air pollutant exposure reduced overstory stem density, but abundance of vegetation in other strata tended to increase along the same gradient. The relative importance of Acersaccharum Marsh. was greatly reduced in all strata with increasing pollutant exposure, whereas Aesculusoctandra Marsh. appeared tolerant of air pollutant stress. In understory strata, the importance of Linderabenzoin (L.) Blume increased with increasing pollutant exposure.
Comparisons of water potentials in bole and needle tissues of lodgepole pine
Authors: Spomer George G. , Stoszek Karel J.
Published: February 2008

Osmotic potentials of combined phloem and cambial tissues from stem plugs were compared with those of needles taken concurrently from the same Pinuscontorta Dougl. ex Loud var. latifolia Engelm. Overall, stem tissue potentials were about twice as high (less negative) as those of needles, and no correlation was found to exist between values from these two tissues. On the other hand, no significant differences existed between potentials in tissues from different heights or between north and south exposures on the same bole.
Comparison of annual ring density profiles in hardwoods and softwoods by X-ray densitometry
Authors: Cown D. J. , Parker M. L.
Published: February 2008

X-ray densitometry was used to study annual-ring density of 15 softwood and 21 hardwood tree species growing on the University of British Columbia campus. Intraring density profiles and some pith-to-bark density trends are presented. Radiographs of transverse wood sections gave the best results in most cases, but radial sections of some ring-porous hardwoods provided superior data. A fixed-density earlywood–latewood boundary criterion is satisfactory for the softwoods studied but less appropriate for most hardwoods. The softwoods vary more than hardwoods in intraring density contrast.
Energy balance and evapotranspiration estimates for a mature coniferous forest
Authors: McCaughey J. H.
Published: February 2008

Results of an energy balance study conducted in 1974 at Montmorency, Quebec, are reported. The energy balance components of a balsam fir (Abiesbalsamea L. Mill.) canopy, evaluated for 7 sample days, show marked differences in energy partitioning. The days are separated into two groups. The difference in the energy balance between the groups is related to the value of volumetric soil moisture in the top 0.1 m of soil. On days when the volumetric soil moisture is 36% or more, potential evapotranspiration conditions are operative, and evapotranspiration is the largest term in the energy balance. Also, it is strongly coupled to net radiation. Whenever the volumetric soil moisture is 32% or less, potential evapotranspiration conditions are not operative, and characteristically, the sensible heat flux to the air is the same or slightly larger than the evapotranspiration. Both fluxes are strongly coupled to the net radiation. For all hours the soil heat flux is negligible. For potential evapotranspiration, the equation developed by Priestley and Taylor is tested. Under potential evapotranspiration conditions the equation, with α = 1.26, estimates daily water loss to within 3%. The Bowen ratio solution to the energy balance is used as the standard for comparison. Whenever the volumetric soil moisture is 32% or less, α is variable and less than 1.26. The minimum value found is 0.67.
Range-wide genetic variation of black spruce
Authors: Morgenstern E. K.
Published: February 2008

Initiation and cessation of growth and total height of seedlings at ages 2 and 3 years were measured in a nursery experiment with 100 seed sources of Piceamariana (Mill.) B.S.P. from natural stands sampled across the range from the Atlantic Coast to Alaska. Correlations with climatic and geographic factors were calculated and principal component, variance, and regression analyses made. The results showed that photoperiod and temperature were major factors of natural selection and that a clinal variation pattern is predominant. Since south–north trends of photoperiod and temperature are closely related to latitude, the regression of phenological variables and of height on latitude of origin gave an indication of response gradients. Total height changed by 2 to 11% from the experimental mean if a seed source was moved 1° of latitude north or south from its native area to a new site. The consequences for seed movement and breeding programs are discussed.
The epicuticular waxes of Pinusstrobus subjected to air pollutants
Authors: Percy K. E. , Riding R. T.
Published: February 2008

The interaction of air pollutants with the epicuticular waxes of eastern white pine (Pinusstrobus L.) needles was investigated. The morphology and distribution of waxes differed between needles from trees growing in locally polluted and unpolluted atmospheres. On needles subjected to air pollutants stomatal occlusion was prominent and structural wax integrity was disrupted. Epicuticular wax modification may be an initial effect of air pollutants.
Rooting potential of Alaskan willow cuttings
Authors: Densmore Roseann , Zasada John C.
Published: February 2008

Rooting potential of cuttings of two riparian and three nonriparian taiga willows was tested under laboratory conditions, and survival of a riparian and a nonriparian species was observed under field conditions. The riparian species, Salixalaxensis (Anderss.) Cov. and Salixnovae-angliae Anderss., rapidly produced roots on all submerged portions of the cuttings. Only a few cuttings of the nonriparian species, Salixscouleriana Barratt and Salixglauca L., produced roots, and only at the basal end of the cuttings. Salixbebbiana Sarg. cuttings did not produce roots.
Short-term temperature variation in needles of Pinussilvestris L.
Authors: Christersson Lars , Sandstedt Roland
Published: February 2008

The temperatures of needles of 10- to 15-year-old trees of Pinussilvestris L. growing in a frost hollow in Sweden were measured with an ultraminiature thermocouple. The measurements were made in the spring of 1977, during days of variable cloudiness. During periods of full sun and very low wind speed the temperature of the needles exceeded that of the surrounding air by 12 to 15 °C.
Control of root morphogenesis for improved mechanical stability in container-grown lodgepole pine
Authors: Burdett A. N.
Published: February 2008

Lodgepole pine (Pinuscontorta Dougl.) seedlings were raised in containers (Styroblocks) painted with a root-growth inhibitor (exterior latex paint containing 0.1 kg/ℓ basic cupric carbonate). Contact with this wall coating completely inhibited the elongation of lateral roots, thereby preventing them from growing down or around the container wall. However, when the seedlings were planted, the inhibited lateral roots very quickly resumed growth. Consequently, the trees soon acquired a root system quite similar in basic form to that of a naturally established seedling.
A modified technique for the determination of fungal mass in decayed wood
Authors: Gurusiddaiah S. , Blanchette Robert A. , Shaw C. Gardner
Published: February 2008

A modified technique to determine fungal mass within decayed wood is presented. The technique is an accurate, rapid method providing excellent separation of glucosamine from amino acids. Equal weights of pure mycelia of Coriolusversicolor (L. ex Fr.) Quél., Hirschioporusabietinus (Dicks, ex Fr.) Donk, and Poriaplacenta (Fr.) Cooke contained different amounts of glucosamine. Chipped forest residues, inoculated with the above basidiomycetes alone and in combination with yeasts, Pichiapinus (Holst) Phaff and Saccharomycesbailii Linder var. bailii, and nitrogen-fixing bacteria, Enterobacter spp., were assayed for glucosamine after 5 (laboratory) and 16 (field) months. More fungal mycelium was present when wood chips were inoculated with H. abietinus or P. placenta than in uninoculated chips. A twofold to threefold increase in glucosamine was observed when these basidiomycetes were combined with yeasts and bacteria.
Southern pine stem form defined through principal component analysis
Authors: Liu C. J. , Keister T. D.
Published: February 2008

not available
Two recent articles on fire ecology
Authors: Wagner C. E. Van , Methven I. R.
Published: February 2008

not available
Performance of plus tree progenies of Pinuscontorta originating north of latitude 55° N in a Swedish trial at 64° N
Authors: Fries Anders , Lindgren Dag
Published: February 2008

This paper deals with the results from a half-sib progeny trial of lodgepole pine (Pinuscontorta ssp. latifolia Engelm.) in Sweden at 64° N. The progenies originate from 69 open-pollinated plus trees selected from 13 areas in British Columbia and the Yukon. The trial was planted on previous agricultural land. At age 10 years, condition and height growth differed significantly between areas of origin and between half-sib families. Northern material was healthier and more vigorous and height growth did not vary clinally with latitude. Stepwise regression analysis with height growth showed that altitude of origin gave a maximum at 650 m and, above 800 m, there was a clear decrease in height growth with increasing altitude of origin. Frequency of extra whorls differed between half-sib families only and was positively correlated with height growth and negatively correlated with forking. Genetic gain by selecting the top 15 parent trees based on 10-year-old progeny trials was estimated to be 10% for volume.
Aboveground biomass distribution within trees and stands in thinned and fertilized Douglas-fir
Authors: Barclay H. J. , Pang P. C. , Pollard D. F. W.
Published: February 2008

Nine years after thinning (removal of 2/3 of the basal area) and fertilization (at 448 kg N ha−1, applied as urea), 34-year-old Douglas-fir trees (Pseudotsugamenziesii (Mirb.) Franco) were destructively sampled. The dry weights of seven aboveground components were determined and regression equations from dbh were developed. Differences among treatments were shown for all biomass components and the proportions of the total biomass allocated to the various components. Specifically, thinning decreased the proportion of biomass allotted to wood, bark, and dead branches, while increasing the proportions in foliage and live branches; fertilization increased the proportion of biomass in branches, but had negligible effects on the proportions of other components.
A comparison of observed and long-run productivity of and demand for inputs in the Canadian lumber industry
Authors: Singh B. K. , Nautiyal J. C.
Published: February 2008

An interrelated factor demand approach was used to study the long-term productivity of and demand for inputs in the Canadian lumber industry covering the period of 1955 to 1982. The long-run, least-cost amounts of labour, capital, roundwood, and energy were obtained by imbedding a cross-stock adjustment process in the share equations of the translog cost function. These least-cost amounts, from which the short-run adjustments were removed, were then used to obtain the long-run productivity of each input. The percentage deviations of the observed amounts of each input from their least-cost levels were computed to determine the degrees of allocative inefficiencies with respect to the individual inputs. Similar deviations of the observed productivity and real total factor costs from their long-run levels were also computed. The results indicated that (i) factor demands in the Canadian lumber industry are actually interrelated, i.e., a disequilibrium in the demand for an input creates compensating adjustments in the demand for other inputs; (ii) there are economies of scale in production of lumber in Canada, but technological progress is unobservable; (iii) simulation of the actual and the least-cost paths of factor utilizations indicated substantial misallocation of each input over major parts of the sample years; (iv) the observed labour productivity increased at the rate of 2.9% per annum while, net of short-run conditions, the rate was 3.7% per annum over the sample period; and (v) productivities of other three inputs declined both on the observed and the long-run productivity paths, but such declines were relatively slower on the long-run paths.
Role of forest tenure in the investment behaviour of integrated Canadian forestry firms
Authors: Nautiyal J. C. , Rawat J. K.
Published: February 2008

Features common to forest tenure systems currently prevalent in different provinces of Canada were noted. Length of tenure and the likelihood of its extension were identified as the crucial elements of tenure for investment purposes. Tenure was found to play an important role in the investment decisions of firms with "site-specific" plants (i.e., plants with buildings, roads, and heavy equipment). Such firms would seek to overcome tenure insecurity by negotiating a tenure as long as the economic life of their plants, implying that government could employ tenure as an instrument to regulate capital investment in large forestry firms.
Foliage and canopy characteristics in relation to aboveground dry matter increment of seven jack pine provenances
Authors: Magnussen S. , Smith V. G. , Yeatman C. W.
Published: February 2008

This paper reports on foliage and tree size data collected in 1984 in an Ontario Pinusbanksiana Lamb, (jack pine) provenance trial established in 1954 at the Petawawa National Forestry Institute, Chalk River, Ont. The ratio of total needle area to needle dry weight of seven provenances showed a substantial within-tree, between-tree, and between-provenance variation that was associated with position within the tree and the average provenance tree size. Provenance mean values ranged from 11.7 to 14.3 m2/kg. The highest values were found in the tallest trees. Tree size and dry matter content varied significantly among provenances, but the relative growth rates of stem volume and aboveground biomass between the ages of 29 and 34 years averaged 5.7 and 4.9% per year in all provenances respectively. Aboveground dry matter production per hectare per year increased linearly with increasing projected leaf area index. The average increase was 1.9 t dry matter per l m2 increase in the leaf area index. Projected leaf area indices for optimally stocked stands averaged 5.0 m2/m2. The results indicated an almost constant net assimilation rate of 1.9 g aboveground dry matter per square decimetre of projected foliage per year in all provenances. Canopy foliage area was strongly correlated with basal area at 1.3 m and stem cross-sectional area at the base of the live crown. Total foliage area per unit basal area averaged 0.31 m2/cm2 at breast height and 0.70 m2/cm2 in the live crown. No significant differences were found between provenances.
Effects of prolonged cold storage on phenology and performance of Douglas-fir and noble fir 2 + 0 seedlings from high-elevation sources
Authors: Tung Chao-Hsiung , Wisniewski Luci , DeYoe David R.
Published: February 2008

Survival, phenology, and growth performance of 2 + 0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and noble fir (Abiesprocera Rehd.) seedlings planted at 1500 m in the Oregon Cascade Range were determined following a lifting on November 7 with 7 months of cold storage or lifting on March 1 with 3 months of cold storage. Storage temperature remained between 1 and 2 °C. There was no difference in Douglas-fir survival attributable to the lifting – cold-storage treatments during the first two growing seasons. The first-season survival of noble fir stored for 7 months was superior to that of those stored for 3 months, but no difference was evident after the second growing season. Timing of bud burst did not differ significantly among treatments for either species. However, the rate of bud burst was significantly greater for noble fir seedlings lifted in November and stored 7 months than for those lifted in March and stored 3 months. No difference in the rate of bud burst was observed between treatments for Douglas-fir. Shoot/root ratio for both species and treatments decreased significantly in the first growing season, but did not change significantly in the second growing season. Regardless of species, no differences were found in height growth or diameter increment between the two lifting – cold-storage treatments for the two consecutive growing seasons. The results suggest that Douglas-fir and noble fir seedlings originating from high-elevation seed sources can be lifted in fall and cold stored for 7 months without adverse effects on seedling performance.
An economic analysis of black spruce breeding in New Brunswick
Authors: Cornelius J. P. , Morgenstern E. K.
Published: February 2008

A representative black spruce (Piceamariana (Mill.) B.S.P.) breeding program was formulated using information collected from New Brunswick Tree Improvement Council cooperators. This "base program" was subjected to program profitability and program efficiency analyses. Costs and revenues were computed for a range of real discount rates. The results showed that variation in discount rates did not greatly influence the break-even level of gross discounted revenue, which was fairly stable at around $100 000 for the base orchard of 5.2 ha. Projected gross discounted revenue ranged from about $100 000 at 4.5% discount rate to $36 at 16%. With the internal rate of return at 4.4%, it was concluded that black spruce breeding is probably an economic means of securing extra wood supplies. The program efficiency component concentrated on resource allocation between plus-tree and family selection. The results suggested that current strategies are close to optimum; for a wide range of numbers of familis selected within a constant budget, gross returns remained within about 10% of the maximum possible for each assumption set. It was concluded that current breeding programs should be continued, with present recommended strategies retained.
The diameter-point method for tree taper description
Authors: Ormerod D. W.
Published: February 2008

The diameter-point method describes the taper of tree boles by a number of submodels joined at points of intrinsic changes in taper along the stem. Each submodel is constructed from equations that predict diameter at three points of relative height and one-parameter profile curves computed directly from these diameters. Advantage is taken of a simple proportional relationship between upper stem diameters at fixed relative intervals of height. Where two submodels join they share the equation that predicts diameter at the join point. The profile curves join without conditioning for continuity of slope. Equations have been developed and analysed for the 32 species–age–location groups used for forest inventory purposes in British Columbia, using three submodels and the Behre hyperbola for the profile curve. The results have shown that the method yields unbiased and precise estimates over the whole stem and is computationally more efficient than the method currently in use in British Columbia.
Physical properties of black cottonwood and balsam poplar
Authors: Kellogg R. M. , Swan E. P.
Published: February 2008

The objective of this study was to characterize selected properties of black cottonwood and balsam poplar to determine whether these species should be distinguished in their utilization. At present, black cottonwood is excluded from the "northern aspen" species group embraced by the National Lumber Grading Agency grading rules for dimension lumber and from use as core material in softwood plywood. Samples of black cottonwood were obtained from three sites in British Columbia. Samples of balsam poplar were obtained from three sites in Alberta. Ten tres were randomly selected from each site and a single 130 cm long bolt was collected immediately above breast height (1.36 m) from each tree. From two trees on each site, three additional bolts of the same length were collected immediately above the height positions located at 25, 50, and 75% of total tree height. The average basic specific gravity of the two species did not differ significantly (black cottonwood, 0.338; balsam poplar, 0.337) in this study. However, differences do exist between site averages, at least for black cottonwood. The initial green moisture contents differ significantly (black cottonwood, 160.5%; balsam poplar, 120.6%) and may be expected to affect their drying requirements differentially. For both species, the specific gravity increases and the green moisture content decreases with increasing height position in the tree. The average fiber length of black cottonwood is significantly longer than that of balsam poplar. The bending properties of strength and stiffness for black cottonwood were found to be significantly greater than for balsam poplar. Variation of these properties with height position in the tree was studied. Fiber length was found to decrease with increasing height position, while the bending strength properties were not affected by height position.
Chemical properties of black cottonwood and balsam poplar
Authors: Swan E. P. , Kellogg R. M.
Published: February 2008

Taxonomically, black cottonwood and balsam poplar are varieties of the same species. However, black cottonwood is excluded from the "northern aspen" species group embraced by the National Lumber Grading Agency grading rules for dimension lumber and from the use as core material in softwood plywood. This study examines the chemical properties of these two species varieties to assess whether continuing differentiation in their utilization is justified. Black cottonwood was sampled at three sites in British Columbia (Fraser Valley, Squamish Valley, Kingcome Inlet) and balsam poplar was sampled at three sites in Alberta (Lodgepole, Slave Lake, Lac La Biche). Representative subsamples of wood and bark meal were prepared from each original sample. Black cottonwood and balsam poplar did not differ significantly in lignin content. Within each species, the heartwood had higher lignin contents than the sapwood. The mean extractive content of the female trees is higher than that of the male trees, but this was statistically significant for only the benzene–alcohol extractive content of the black cottonwood sapwood. The pH and acidity did not differ significantly between species. However, there was a large difference between heart-wood and sapwood pH values in both species; sufficient to provide a basis for their differentiation. Acidity values were higher for both sapwoods than for heartwoods. The chemical component contents of black cottonwood and balsam poplar bark were the same, except for the benzene–alcohol extractive content, which was twice as great in balsam poplar. However, the same chemical components were found in each extractive mixture. Results do not provide any basis for separate commercial utilization of these two varieties of the same species.
Variation in seed set and proportions of outcrossed progeny with clones, crown position, and top pruning in a Douglas-fir seed orchard
Authors: Omi S. K. , Adams W. T.
Published: February 2008

The effects of clonal variability, crown position of cones, and top pruning on the proportions of viable outcrossed progeny [Formula: see text] and filled seeds (PF) were investigated in a 20-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seed orchard. Estimates of [Formula: see text] were derived by means of a maximum likelihood procedure from data from 10 allozyme loci. Values for [Formula: see text] and PF were significantly heterogeneous (P < 0.05) among six selected clones for all pruning treatment x clone combinations. On the average, estimated values for [Formula: see text] and [Formula: see text] were greater in seeds collected from the upper crown [Formula: see text] than from the lower crown [Formula: see text]. Combined over crown positions, pruning appeared to have little effect on [Formula: see text], although the proportion of filled seeds was slightly lower in pruned ramets [Formula: see text] than in unpruned ramets [Formula: see text]. The overall frequency of viable selfs [Formula: see text] in the progeny of the six clones was 0.08.
The growth and yield responses of a high site quality red pine plantation to seven thinning treatments and two thinning intervals
Authors: Liechty Hal O. , Mroz Glenn D. , Reed David D.
Published: February 2008

Seven thinning treatments with residual densities between 60 and 160 ft3/acre (13.8 and 36.8 m2/ha) of basal area were applied to a highly productive (site index, 81 ft (24.7 m); base age, 50 years) red pine (Pinusresinosa Ait.) plantation. After 10 years, periodic basal area growth was maximized over a lower and much broader range of residual densities than previously found in lower site quality stands. Total and merchantable cubic foot volume growth for the 10 year period was not significantly different between treatments. Application of these thinning treatments on a 6- compared with a 10-year interval reduced total and merchantable cubic foot volume growth while increasing the average stand diameter.
A two-stage matrix model for predicting growth of forest stands in the Northeast
Authors: Solomon Dale S. , Hosmer Richard A. , Hayslett Jr. Homer T.
Published: February 2008

Matrices are used to model ingrowth, survivor growth, and mortality for stands in different forest types in the Northeast. Equations are developed for several species from softwood and northern hardwood stand data estimating the probability of trees remaining in a diameter class, increasing one or two diameter classes, or dying. By knowing species composition and diameter distribution, FIBER predicts stand yields for managed and unmanaged stands with densities ranging from 9.2 to 41.3 m2/ha using 5-year iterations. Actual and predicted volume estimates from independent data sets are compared for different species compositions, densities, thinning operations, and harvest intervals in the softwood, northern hardwood, and mixed-wood forest types.
Organic matter dynamics of fine roots in plantations of slash pine (Pinuselliottii) in north Florida
Authors: Gholz Henry L. , Hendry Laurel C. , Cropper Jr. Wendell P.
Published: February 2008

Seasonal patterns of live, dead, and unknown viability fine (diameter, ≤10 mm) roots of pine and other vegetation in a young and old slash pine stand were sampled using monthly soil coring over a 24-month period. A distinct unimodal pattern for roots <1 mm in diameter in the surface soil was observed. Live roots increased in the spring to a peak in midsummer and then declined. Larger roots and roots deeper in the soil showed less distinct seasonal patterns, although maximum and minimum annual biomass values were sometimes significantly different. Decomposition of fine roots in buried mesh bags averaged 15–20% per year for roots <5 mm in diameter. An analysis of seasonal dynamics and decompositon rates were combined to construct organic matter budgets for the forest floor and soil. Estimated net root production for roots ≤10 mm in diameter was 590 and 626 g m−2 year−1 in the young and old stand, respectively. Root turnover contributed 214 and 452 g m−2 year−1 to detrital pools on the two sites, with the balance of production accumulating as standing root biomass or lost in decomposition. Root production and turnover rates decreased with increasing root diameter; most production was from roots <1 mm. Pine root production was greater and nonpine production was less in the older stand than in the younger stand. Compared with other temperate and boreal forests, root biomass was high and net root production relatively low. The low production:biomass ratio may be characteristic of low latitude (warm) and (or) low nutrient forest types.
The variety of soil microsites created by tree falls
Authors: Beatty Susan W. , Stone Earl L.
Published: February 2008

The uprooting of forest trees leads to the formation of microsites on the forest floor, contributing to fine-scale heterogeneity in soil properties. We found the types of microsites formed depended on the way the tree fall occurred. Tree falls were classified as either hinge or rotational types. Hinge tree falls formed when the root mat of a tree and the surrounding soil were uplifted vertically, leaving an adjacent pit in the soil. Hinge tree falls varied as to thickness of the root mat and angle of uplift. Rotational tree falls were usually a result of a ball and socket motion of the root mat and soil, which positioned the tree bole over the newly created pit. The tree falls disrupted and redistributed surface soil organic matter and subsoil. In rotational tree falls, the surface material remained intact, covering some of the pit and the adjacent side of the mound. In hinge tree falls, the surface organic matter was deposited on the throw side of the mound, leaving subsoil on the other side and in the pit. With time, however, hinge-type pits accumulated litter and eventually had more organic matter than mounds. Old mounds from both hinge and rotational tree falls had lower concentrations of calcium and magnesium, lower pH, and less moisture than pits. The tree fall process creates long-term soil patterns and maintains microsite heterogeneity in forest communities.
Insitu measurements of sulfate incorporation into forest floor and soil organic matter
Authors: Strickland Timothy C. , Fitzgerald John W. , Swank Wayne T.
Published: February 2008

Litter and soil from a mixed mature hardwood forest were examined for the capacity to incorporate 35S-labelled sulfate into organic matter insitu. Amounts of sulfate incorporated within 48 h of field incubation were 70, 49, and 18% of added 35S per gram of substrate in the O1, O2, and A horizons, respectively. These potentials increased in the respective horizons to 74, 61 and 29% after 7 days. The incorporated 35S was predominately in the form of carbon-bonded S (17–48% of added 35S). Insitu incorporation rates exceeded rates previously estimated by laboratory incubations and the former rates showed a positive response to increase sulfate loading.
Estimation of bole volume by importance sampling
Authors: Gregoire Timothy G. , Valentine Harry T. , Furnival George M.
Published: February 2008

A sampling methodology to provide an unbiased estimate of bole volume is introduced, with specific regard to its incorporation as an alternative to detailed dendrometry in a 3P sampling framework. In a demonstration of the technique to estimate merchantable volume in a 91-tree population, the average relative sampling error was 7.4%. A two-tool implementation of 3P sampling is proposed and discussed.
Forest development in canopy openings in old-growth Pseudotsuga forests of the western Cascade Range, Oregon
Authors: Stewart Glenn H.
Published: February 2008

Size and age structure, and spatial pattern analysis were used to study the population dynamics of old-growth Pseudotsugamenziesii (Mirb.) Franco forests of the western Cascade Range, Oregon, U.S.A. Tree population structures confirmed that in the absence of fire, Pseudotsuga was replaced by Tsugaheterophylla (Raf.) Sarg. and (or) Abiesamabilis (Dougl.) Forbes. Regeneration patterns of these species reflected establishment in canopy openings or under Pseudotsuga, but not under Tsuga. Abiesamabilis occurred more frequently as seedlings and saplings in openings than did Tsuga because of favourable aspects of its life history. The composition and structure of the pioneer forest developing after fire was a determinant of subsequent regeneration. If Pseudotsuga dominated, Tsuga and Abies invaded the stand at an early stage. Regeneration in stands where Tsuga was a large component, however, was limited by dense canopies and the occurrence of canopy openings. These patterns demonstrate the importance of small-scale disturbances such as tree falls in the dynamics of Pacific Northwest conifer forests.
Effect of soil salinity on stomatal conductance and photosynthesis of green ash (Fraxinuspennsylvanica)
Authors: Pezeshki S. R. , Chambers J. L.
Published: February 2008

Seedlings of green ash (Fraxinuspennsylvanica Marsh.) were subjected to four levels of salt water ranging from approximately seawater concentration to one-tenth the concentration of seawater to simulate a temporary intrusion of salt water in coastal areas and brine spills associated with oil-drilling activities. The effect of saltwater influx on subsequent stomatal behaviour and net photosynthesis was studied. Stomatal conductance was reduced up to 72% and net photosynthesis declined by as much as 86% in response to the application of saline water. Both responses were rapid and occurred shortly after treatment. In addition to substantial declines in stomatal conductance and net photosynthesis, plant water potential also declined after treatment. All levels of salt application resulted in leaf injury and the two highest concentrations caused rapid seedling mortality. The results of this study indicate that green ash seedlings are extremely sensitive to soil salinity and will not survive either saltwater intrusion or brine spills associated with oil-drilling activities. Potential long-term effects are discussed.
Role of species composition in relative density measurement in Allegheny hardwoods
Authors: Stout Susan Laurane , Nyland Ralph D.
Published: February 2008

Two frequently used measures of relative stand density, the tree area ratio and the stand density index, were fitted to data from Allegheny hardwood stands. Both were modified to reflect the influence of species composition, since the proportion of the basal area in different species groups had an important effect on the measurement of relative stand density in this mixed species forest type. The tree area ratio model provided a better fit to the data than the stand density index model, particularly when adapted to include three species groups: one based on Prunusserotina Ehrh. and Liriodendrontulipifera L., one based on Acerrubrum L., and one based on Acersaccharum Marsh, and Fagusgrandifolia Ehrh.
Incorporating feedback mechanisms into forestry decision making
Authors: Harou P. A.
Published: February 2008

Systematic feedbacks between actual and estimated cash flows should allow forestry projects to be compared with abandonment alternatives. The forestry project monitoring circle and the alternative test are briefly described and applied to forestry investments. The use of periodic feedbacks together with the alternative test improve the expected profitability of the projects and decrease their "perceived" uncertainty or risk.
Development of lenticels and adventitious roots in flooded Ulmusamericana seedlings
Authors: Angeles G. , Evert R. F. , Kozlowski T. T.
Published: February 2008

Flooding of soil for 31 days reduced growth, induced marginal leaf necrosis and abscission, caused decay of root systems, and induced morphological and anatomical changes in 10-week-old Ulmusamericana L. seedlings. The seedlings adapted to flooding by forming hypertrophied lenticels and adventitious roots on submerged portions of stems, as well as forming new roots on preexisting roots. Hypertrophy of the lenticels resulted from accelerated phellogen activity and elongation of cork cells. The increased phellogen activity extended beyond the lenticels and often resulted in ruptures of the epidermis encircling the entire stem circumference. The flood-induced adventitious roots on stems originated denovo in the ray parenchyma of the secondary phloem.
Death by attrition: a hypothesis for wave mortality of subalpine Abiesbalsamea
Authors: Marchand Peter J. , Goulet France L. , Harrington Thomas C.
Published: February 2008

Wave mortality in subalpine Abies forests of the northeastern United States is characterized by the progressive dieback of overstory dominants in a compact zone that advances systematically through mature stands and is followed by vigorous regeneration of the overstory species. The principal driving force for this dieback appears to be exposure at the edge of canopy gaps to very high winds. In this study, individual trees at the leading edge of a dieback front and trees in a thinned plot within the mature stand downwind of the advancing wave both experienced a substantial decline in foliage mass and, consequently, in prebudbreak foliar starch pool over a 2-year period. In the case of the thinned stand, this reduction was attributed to a large increase in wintertime green litter fall. Increased exposure at the wave front and in the thinned stand also resulted in a dramatic increase in root damage relative to control trees. Coincidental to breakage of roots, root xylem discoloration (attributed to wounding and invasion by root pathogens) was greater on trees at the wave front than on trees in the mature zone. Loss of active foliage and roots was accompanied by a two- to five-fold reduction in annual wood increment among dieback zone trees. These data suggest that exposed trees, which suffer a substantial reduction in crown size and foliage carbohydrate pool in an environment where growth is marginal to begin with, may not be able to keep up with the increased energy demand for root and foliage turnover and eventually suffer death by attrition of both tissues.