bluuebunny/crossref_metadata_2025 huggingface dataset:
Carotenoid profiles of yeasts belonging to the genera Rhodotorula, Rhodosporidium, Sporobolomyces, and Sporidiobolus
Authors: Buzzini Pietro , Innocenti Marzia , Turchetti Benedetta , Libkind Diego , van Broock Maria , Mulinacci Nadia
Published: September 2007

Eighteen yeast species of the genera Rhodotorula , Rhodosporidium , Sporobolomyces , and Sporidiobolus , each one represented by its type strain, were investigated with the objective of evaluating their carotenoid composition. The pigments were extracted from yeast cells, quantified by high pressure liquid chromatography diode array detector and the main compounds were confirmed by atmospheric pressure chemical ionization quadrupole mass spectrometry. Significant (P < 0.01) differences among several species and (or) genera were observed. Thirteen strains were seen to be able to produce carotenoids, from 16.4 to 184 μg/g cell dry mass and from 6.0 to 1993.4 μg/L culture. The main carotenoids produced were identified as torularhodin, torulene, γ-carotene, and β-carotene. The correlation matrix calculated on the basis of the carotenoid composition data matrix indicated significant (P < 0.01) relationships between torulene and torularhodin (r = 0.81), γ-carotene and torulene (r = 0.49), β-carotene and torulene (r = –0.72), as well as β-carotene and γ-carotene (r = 0.64). These significant correlation coefficients may suggest that species belonging to the genera Rhodosporidium, Sporobolomyces, and Sporidiobolus possess a carotenoid biosynthetic pathway analogous to that elsewhere postulated for Rhodotorula species.
Greenhouse environment and epidemiology of grey mould of container-grown Douglas-fir seedlings
Authors: Peterson Michael J. , Sutherland Jack R. , Tuller S. E.
Published: September 2007

The environmental parameters associated with grey mould, Botrytiscinerea Fr.: Nocca & Balbis, on container-grown Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco, were studied in a plastic-covered greenhouse and a fibreglass-covered greenhouse near Victoria, British Columbia. Disease losses and numbers of B. cinerea spores were much higher in the fibreglass-covered house, where seedlings were taller and more succulent because the fibreglass reduced light intensities. From July to October the length of time when the combination of temperature and relative humidity that favours B. cinerea spore germination and infection was 14.5 times greater in the fibreglass-covered than in the plastic-covered house. Conditions beneath the seedling canopy that enhance the disease were more prevalent in July and August than in the autumn when the disease becomes evident, suggesting that earlier application of preventive fungicides may benefit disease control. Grey mould inoculum originated from outside the greenhouses, but once the disease was established on the seedlings, numbers of spores within the houses exceeded those outside. Airborne spore numbers both outside and within the greenhouses were highest during the day. Numbers of spores within the houses peaked when the irrigation system was on; this is ascribed to the mechanical effect of the irrigation water on spore dispersal rather than to changes in greenhouse environmental parameters.
The effects of overrun improvements on stumpage price inflation
Authors: Cardellichio Peter A. , Binkley Clark S.
Published: September 2007

Overrun has been increasing in United States sawmills, particularly in recent years. While some of this increase may be attributed to log scaling biases, a substantial portion is apparently due to technological improvement. Have these technological improvements increased or dampened the rate of stumpage price inflation? Proponents of residual pricing theory argue that higher overrun causes stumpage prices to increase because lumber producers are able to pay more for stumpage. On the other hand, some analysts argue that higher overrun causes stumpage prices to fall by reducing the demand for stumpage. This paper addresses the controversy by means of a simple theoretical model of an integrated lumber market. The effect of improved overrun on stumpage price inflation is ambiguous and depends on the elasticity of both lumber demand and stumpage supply. However, by choosing reasonable values for key parameters, we conclude that at the level of the large producing region, say the Pacific Northwest, technology-based overrun improvements have most likely slowed the rate of stumpage price inflation.
Photosynthate translocation during union development in Picea grafts
Authors: Beeson Jr. R. C. , Proebsting W. M.
Published: September 2007

Rootstocks (Piceaabies (L.) Karst.) and scions (Piceapungens Engelm.) were labelled separately during graft union development with 14CO2 and translocation of the labelled photosynthate determined qualitatively and quantitatively. Rootstock photosynthates did not cross the graft union after scion budbreak had started. Total recovery of labelled scion photosynthates in scions declined from nearly 60% to less than 10% during the 1st week after grafting, and did not increase until xylem connections were established 1-2 weeks before budbreak. Less than 2% of the recovery from the scion was found in the graft union before scion budbreak. Most of the label recovered before scion budbreak was in the needle sugar fraction. After budbreak, most of the label was recovered in elongating buds.
The separation of Betulapopulifolia and Betulapendula and their status in Ontario
Authors: Catling P. M. , Spicer K. W.
Published: September 2007

The North American Betulapopulifolia differs from the European Betulapendula in having a larger number of peltate resin glands on greyish twigs, leaves with long–caudate tips, and a dense pubescence on the adaxial surface of the pistillate scales. Furthermore, B. populifolia is a plant of acid, peaty, or sandy substrates, whereas B. pendula grows in acid to neutral or occasionally slightly alkaline substrates. The bark of B. pendula exfoliates in long thin strands, whereas in B. populifolia it exfoliates as small, very thin rectangular flakes or appears not to exfoliate at all. The basal parts of older trunks of B. pendula often develop vertical fissures, which never develop in B. populifolia. Analysis of variance suggests that the most useful quantitative characters for distinguishing the two species are scale width and the length/width ratio of the terminal one-quarter of the leaf. Several other quantitative characters are useful discriminators but are not entirely reliable by themselves. Discriminant analyses with and without qualitative characters separated a sample of North American B. populifolia from a sample of European B. pendula. The derived discriminant formula placed many members of a variable natural population from near Ottawa in an intermediate position, suggesting hybridization. The use of heavily weighted qualitative characters in the discriminant formula placed much of the hybrid population in the B. populifolia group, whereas the use of quantitative characters alone placed much of the hybrid population in the B. pendula group. As putative hybrids are being widely distributed by nurseries, the identification of the two species is likely to become increasingly problematic. Betulapendula is a widespread and naturally spreading escape from cultivation in southern Ontario, while B. populifolia is a native species confined in Ontario to the eastern portion of the province between the Ottawa and St. Lawrence rivers, with a possible outlier in Elgin County in southwestern Ontario.
Construction of a stand growth model utilizing photosynthesis and respiration relationships in individual trees
Authors: Sievänen Risto , Burk Thomas E. , Ek Alan R.
Published: September 2007

A discrete growth model for an individual tree in a forest stand is presented. The model is based on simplified photosynthesis and respiration relationships. Implementation of the model also requires functions for change in live crown ratio and stems per unit area. Tree growth predictions are expressed in terms of biomass and basal area. A preliminary evaluation of the model is made using data from the literature on the growth of even-aged stands of red pine (Pinusresinosa Ait.). The model produced both short- and long-term trends consistent with stand growth data. The evaluation suggests further possibilities for model component refinement.
Effects of acid mist on invivo pollen tube growth in red maple
Authors: Ryn D. M. Van , Lassoie J. P. , Jacobson J. S.
Published: September 2007

The effects of mist acidity on invivo pollen germination and tube elongation of red maple (Acerrubrum L.) were investigated. Branches with female flowers were exposed to simulated mist at pH values of 5.6, 4.6, 3.6, and 2.6. After exposure, stigmas were pollinated with fresh, untreated pollen. Following a growth period of 24 h, styles were excised, stained, and observed with fluorescence microscopy to determine the number of grains that had germinated and the number of tubes that had grown to the base of the style. Both germination and tube growth were sensitive to the pH of mist. During one trial, as mist pH decreased from 5.6 to 2.6, the mean number of grains that germinated decreased from 60 to 19 and the mean number of tubes that grew to the base of the style decreased from 3.8 to 1.0. Only at pH 2.6 was there a significant relationship between number of germinating pollen grains and number of tubes reaching the base of the style. The effects of acidity on pollen germination invivo were similar to, but not as severe as, those obtained previously with pollen germinated invitro.
Genetic variation in aspects of leaf growth of Populusclones, using the leaf plastochron index
Authors: Ceulemans R. , Impens I. , Steenackers V.
Published: September 2007

Leaf growth characteristics of seven clones of Populustrichocarpa, P. nigra, and interspecific hybrids with P. deltoides were examined on 1-year-old cuttings grown in a controlled-environment growth chamber. The plastochron index, a morphological time scale that is a linear function of time and correlated with other morphogenetic and physiological developmental processes, was applied to this development and growth study. Uniformity of leaf initiation was studied; new leaves were initiated at regular time intervals, at least under the controlled conditions of this study. Clones with a high leaf production rate (e.g., P. nigra clone Italica) had a low leaf growth rate and leaves reached maturity at a high leaf plastochron index (LPI 11). Fast-growing and high-yielding P. trichocarpa × P. deltoides hybrids showed the highest leaf growth rates and had a similar leaf production rate to P. trichocarpa. Despite considerable differences in leaf production rates, leaf maturity, and absolute leaf growth rates, only small differences in relative leaf growth rate were observed among the clones.
Equations for estimating aboveground components of young Douglas-fir and red alder in a coastal Oregon plantation
Authors: Helgerson Ole T. , Cromack Kermit , Stafford Susan , Miller Richard E. , Slagle Rod
Published: September 2007

Localized log–log regression equations were developed for young red alder (Alnusrubra Bong.) and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) to predict branch and leaf dry weights from branch diameters, and leaf and branch dry weights (predicted from branch diameters), bole volumes and weights, and tree heights from stump and breast-height diameters. Correlation coefficients were generally greater than 0.9. These equations will be useful for similar sites in estimating aboveground biomass at precommercial thinning, fuel loadings, nutrient cycling, and productivity.
Accelerated short-term genetic testing for loblolly pine families
Authors: Williams Claire G.
Published: September 2007

The following experiment was done to test the hypothesis that acceleration of seedling growth increases the juvenile–mature correlation for growth. Growth traits of 18 open-pollinated loblolly pine (Pinustaeda) familes were compared across (i) field trials measured 8 years after planting (mature age), (ii) a short-term test environment with a supplemental incandescent light source (20-h photoperiod) and a higher fertilizer level, and (iii) a short-term test environment with no supplemental day length and a lower fertilizer level. The ranking of two seedlots of known, extreme performance and the juvenile–mature correlations were used as the criteria of early testing success. Juvenile–mature (family mean) correlations were low (r = 0.13) for the growth-accelerating environment relative to the natural day length environment (r = 0.59) and two check seedlots ranked correctly only in the natural day length environment. The genetic correlations between the short-term tests are high for total height [Formula: see text] but lower for height produced after first budset, the trait that has shown value as a juvenile indicator [Formula: see text] The growth-accelerating treatment increases growth per unit time but prompts abnormal shoot development. The nonaccelerating treatment with no supplemental light offered the most promise for genetic testing of 1st-year loblolly pine seedlings.
Canopy profiles of some Piedmont hardwood forests
Authors: Hedman Craig Wallace , Binkley Dan
Published: September 2007

Relationships between canopy profiles and site quality were examined in 11 old, uneven-aged (>180 years) hardwood forests in the Piedmont of eastern North Carolina. Site fertility was indexed by extractable soil calcium and phosphorus, by the content of calcium, phosphorus and nitrogen in litter fall, and by the aboveground net primary productivity of each stand. Canopy profiles were indexed by the leaf area index for each 3.3-m height interval. Total leaf area index correlated highly with most measures of site fertility, but we found no clear patterns between canopy profiles and any measure of site fertility. We conclude that site fertility is reflected in broad ecosystem-level variables such as total leaf area index and stand productivity, but that detailed patterns such as canopy profiles relate strongly to specific stand composition, age structure, and history.
Spruce–fir decline and gap dynamics on Camels Hump, Vermont
Authors: Perkins T.D. , Klein R.M. , Badger G.J. , Easter M.J.
Published: September 2007

Widespread and conspicuous dieback of red spruce (Picearubens Sarg.) accompanied by asymptomatic declines in balsam fir (Abiesbalsamea (L.) Mill.) and white birch (Betulapapyrifera var. cordifolia (Regel.) Fern.) trees on Camels Hump, Vermont, prompted an investigation into the role of spruce–fir decline on gap expansion, tree health, and regeneration dynamics. Forty percent of the study area on Camels Hump was occupied by recent forest gaps in the summer of 1989. Gaps were growing northwesterly (direction 322°) at a rate of 0.8–1.2 m•year−1. Prevailing winds in the study area are from the south-southeast. Gap expansion appears to play a dominant role in continuing forest disturbance. Red spruce vigor was low in all dominance classes (53% foliar retention), while vigor of balsam fir and birch (yellow (Betulaalleghaniensis Britt.) and white) was somewhat higher. Exposure and wind flagging of different tree species within the same crown dominance classes were similar, but apical foliar damage was greater in spruce than in fir or birch. Red spruce and birch trees were older than balsam fir within comparable crown classes. Wind flagging was significantly correlated with crown exposure in red spruce and balsam fir, while diameter was the most important factor related to flagging in birch. All three species tended to die while standing. Dead balsam fir trees were twice as likely as red spruce to have been windthrown or diseased, whereas dead red spruce showed a much higher incidence of past and present insect infestation. Live birch had low levels of biotic damage. Density of red spruce seedlings was low within gaps and adjacent canopy sites. Balsam fir seedling density was significantly higher in the canopied areas, whereas birch density was marginally higher in gap areas. There were no significant differences in ages of spruce or fir seedlings growing in gaps and closed canopy areas. Birch seedlings in gaps were older and taller than those under the canopy, indicating low survivorship of birch under the forest canopy. It is likely that this forest will be predominantly composed of balsam fir and birch in the near future.
Timber harvest scheduling in a fuzzy decision environment
Authors: Bare B. Bruce , Mendoza Guillermo A.
Published: September 2007

Linear programming is a widely used tool for timber harvest scheduling in North America. However, some potential problems related to infeasible harvest schedules, overly optimistic objective function values, and the need to strictly satisfy all constraints included in deterministic model formulations have been raised. This paper describes a fuzzy approach for explicitly recognizing the imprecise nature of the harvest flow constraints usually included in harvest scheduling models. The objective function and selected constraints are viewed as soft, and satisfactory solutions are derived and discussed for several scenarios. An illustrative sample problem is presented to demonstrate the methodology, and a comparison with solutions derived from a traditional linear programming model is presented.
Some considerations when selecting young jack pine families using growth and form traits
Authors: Morris Dave M. , Parker William H. , Seabrook Rod
Published: September 2007

The purpose of this study was to provide background information on the heritabilities and genetic correlations for important growth and form traits in 3-year-old jack pine (Pinusbanksiana Lamb.) to help evaluate an experimental five-category quality index. Height, diameter, crown diameter, number of branches, number of stem crooks, number of leaders, and crown density were recorded for 3-year-old progeny of 400 jack pine families at the Blue Bird Lake family test in northern Ontario. Narrow-sense (single-tree) heritabilities ranged from 0.08 for crown diameter to 0.17 for height, but no measurable component of family variance was associated with number of leaders. Genetic correlations were negligible between growth and some form characters, but were very high and unfavourable for number of crooks versus height and diameter (0.93 and 0.82, respectively). Thus, the preliminary indication is that selection for maximum increase in growth rate will result in a trade-off in terms of number of stem crooks. It was determined that the experimental quality index could not be used as a stand-alone selection tool. Discriminant analysis indicated that a high level of error (38%) in assigning progeny to the five quality classes existed. This error may be caused by overlap between quality classes, errors made in evaluation by field personnel, or most likely the inability to summarize overall tree form based on the five form traits determined for this study.
Activity of sucrose synthase and soluble acid invertase following germination of pinyon (Pinusedulis) seeds
Authors: Murphy J. Brad , Rutter Mark R. , Hammer Mark F.
Published: September 2007

The developmental pattern and relative activities of sucrose synthase (EC 2.4.1.13) and soluble acid invertase (EC 3.2.1.26), and the associated contents of sucrose and hexoses, were analyzed in the cotyledons, hypocotyl, and radicle of pinyon (Pinusedulis Engelm.) seedlings following radicle emergence. Sucrose synthase activity did not appear to be correlated with organ growth, but showed a close association with sucrose content. Conversely, there was a high degree of correlation between soluble acid invertase activity and growth of the various organs. Hexose content also was correlated with the level of invertase activity. Thus, soluble acid invertase appeared to be directly involved in providing respiratory and biosynthetic substrates in growing organs, while the role of sucrose synthase was less clear, being more active in tissues that are involved in sucrose import and transport and possibly sucrose to starch conversion.
Nutrient cycling in Huntington Forest and Turkey Lakes deciduous stands: nitrogen and sulfur
Authors: Mitchell M.J. , Foster N.W. , Shepard J.P. , Morrison I.K.
Published: September 2007

Biogeochemical cycling of S and N was quantified at two hardwood sites (Turkey Lakes watershed (TLW) and Huntington Forest (HF)) that have sugar maple (Acersaccharum Marsh.) as the major overstory component and are underlain by Spodosols (Podzols). TLW and HF are located in central Ontario (Canada) and the Adirondack Mountains of New York (U.S.A), respectively. Major differences between the TLW and HF sites included stand age (300 and 100 years for TLW and HF, respectively), age of dominant trees (150–300 and 100 years for TLW and HF, respectively), and the presence of American beech (Fagusgrandifolia Ehrh.) at HF as well as lower inputs of SO42− and NO3− (differences of 99 and 31 mol ion charge (molc)•ha−1•year−1, respectively) at TLW. There was an increase in concentration of SO42− and NO3− after passage through the canopy at both sites. A major difference in the anion chemistry of the soil solution between the sites was the much greater leaching of NO3− at TLW compared with HF (1300 versus 18 molc•ha−1•year−1, respectively). At HF, but not TLW, there was a marked increase in SO42− flux (217 molc•ha−1•year−1) when water leached from the forest floor through the mineral soil. The mineral soil was the largest pool (>80%) of N and S for both sites. The mineral soil of TLW had a C:N ratio of 16:1, which is much narrower than the 34:1 ratio at HF. This former ratio should favor accumulation of NH44+ and NO3− and subsequent NO3− leaching. Laboratory measurements suggest that the forest floor of TLW may have higher N mineralization rates than HF. Fluxes of N and S within the vegetation were generally similar at both sites, except that net requirement of N at TLW was substantially lower (difference of 9.4 kg N•ha−1•year−1). The higher NO3− leaching from TLW compared with HF may be attributed mostly to stand maturity coupled with tree mortality, but the absence of slow decomposing beech leaf litter and lower C:N ratio in the soil of the former site may also be contributing factors.
Régénération après feu de l'épinette noire (Piceamariana) et du pin gris (Pinusbanksiana) dans la forêt boréale, Québec
Authors: St-Pierre Hélène , Gagnon Réjean , Bellefleur Pierre
Published: September 2007

Age structure analysis was performed in black spruce (Piceamariana (Mill.) B.S.P.) and jack pine (Pinusbanksiana Lamb.) stands following fire (i) to determine if there is a time lag between black spruce and jack pine establishment and (ii) to compare the composition of the regeneration with regard to the original stand. The study was conducted in an area burnt in 1983, 100 km northwest of Lake Saint-Jean, Quebec. Five years after fire, the age structure of the regeneration shows an early establishment of jack pine and black spruce, with more than 95% of the seedlings established during the first three growing seasons after fire (excluding the year of fire). The age structures were similar in mature stands and in the regeneration for the jack pine while they differed for black spruce. Errors in age determination due to suppression of adult trees sampled or other causes could explain the difference in the establishment pattern of young and mature black spruces. Compared with the mature stand, the postfire regeneration had an increased proportion of jack pine. The study concludes that both species can regenerate shortly after fire, but in somewhat varying proportions.
Crooked leaders and nutrition in Fraser fir Christmas trees
Authors: Hinesley L. Eric , Campbell C. Ray
Published: September 2007

Current-year foliage from the upper crown of Fraser fir (Abiesfraseri (Pursh) Poir.) Christmas trees with normal and abnormally spiraled or crooked leaders was sampled monthly between July and November over a 3-year period. Bark, wood, and small roots were also collected in November 1988, and foliage was collected from the upper whorl and leader on two dates in 1989. Concentrations of several nutrients varied significantly between crooked and straight trees in some years, but not across all years. With several elements, changes in concentration during the growing season were inconsistent across years. Some differences were too small to be of practical significance; others favored trees with crooked leaders when compared with nutritional guidelines. Concentrations of all elements varied considerably among trees, and nearly all nutrients exhibited significant temporal changes in concentration during the growing season. Concentrations also varied by sampling position. Nitrogen concentration tended to be higher in the foliage of crooked trees. Because there was no consistent pattern of deficiency, excess, or imbalance for any particular nutrient, the crooked leader problem in Fraser fir appears to have no distinct nutritional basis.
Isozyme variation in quaking aspen in Minnesota
Authors: Lund Steven T. , Furnier Glenn R. , Mohn Carl A.
Published: September 2007

Variation at 10 polymorphic isozyme loci was examined for nine populations of quaking aspen (Populustremuloides Michx.) in Minnesota. Mean observed and expected estimates of isozyme heterozygosity were 0.217 and 0.220, respectively, with no significant differences in allele frequencies among populations and no significant deviations from genotype frequencies expected under Hardy–Weinberg equilibrium. These results suggest relatively high levels of gene flow among populations and a mating system involving little inbreeding.
Opportunity costs of regional income redistribution: evidence from reforestation investments in British Columbia
Authors: Kooten G.C. van , Thompson W.A. , Vertinsky I.
Published: September 2007

More than half a million hectares of productive forest land in British Columbia have gone out of production because of inadequate reforestation following timber harvesting or destruction of the forest by insects or fire. Investments in reforestation of this backlog, not sufficiently restocked forest land are an important instrument of regional development in British Columbia. In this paper, economic efficiency losses associated with various allocations of reforestation funds among three regions of the province are examined. Income distributional weights are imputed for these regions based upon the allocation of reforestation monies. The results indicate that economic inefficiencies may arise from overinvestment in reforestation and from ignoring economic criteria in the prioritization of sites for treatment. However, there is evidence that the opportunity costs associated with regional equity concerns are not large.
Peat water content measurement using time domain reflectometry
Authors: Pepin Steeve , Plamondon André P. , Stein Jean
Published: September 2007

The calibration of time domain reflectometry, previously established for an organic soil of 0.422 Mg•m−3 bulk density, was established for peat blocks with bulk densities ranging from 0.06 to 0.25 Mg•m−3. An empirical relationship between the volumetric water content and the measured apparent dielectric constant was established in the laboratory. This relationship can be used to estimate volumetric water content between 0.21 and 0.95 cm3•cm−3 with a standard deviation of 0.03 cm3•cm−3. The large variations observed during the calibration were mainly attributed to the size and heterogeneousness of peat samples. When water tables in the field were high, standard deviation decreased to 0.02 cm3•cm−3, which agrees very well with other time domain reflectometry experiments.
Influence of spacing and short rotations on Populustrichocarpa × deltoides coppice
Authors: Auclair Daniel , Bouvarel Luc
Published: September 2007

Height growth and dry woody biomass production were studied on Populustrichocarpa × deltoides (Beaupré) coppiced at 1-, 2-, and 3-year intervals on a converted woodland in central France. For each rotation, two different planting densities were studied, ranging from 2000 to 20 000 cuttings per hectare. The experiment, which lasted for 6 years, allowed comparisons between establishment and subsequent coppice cycles on relatively large treatment plots (400 stools per plot). The highest planting densities yielded fewer shoots per stool and reduced height and diameter growth. Individual stool biomass was reduced by high stool densities; however, total biomass per unit area was higher, resulting from the greater number of stools. Height growth was greatly influenced by climatic variability, principally rainfall. Biomass production was greater after coppicing than during the establishment phase for the 2- and 3-year rotations, in spite of low water availability. Biomass production decreased in the 1-year rotation during 3 years, but was subsequently followed by a higher production, in strong relation with water availability. At the planting density of 5000 per hectare, total biomass yield was higher for the longest rotations. There was no evidence of ageing of the stumps even after six 1-year rotations.
Role of Armillaria calvescens and Glycobius speciosus in a sugar maple decline
Authors: Bauce Eric , Allen Douglas C.
Published: September 2007

Sugar maple, Acersaccharum Marsh., decline may be reversible during early stages before secondary insects and fungi invade stressed trees. Treatment with boric acid reduced the regenerative capacity of Armillariacalvescens Bérubé & Dessureault rhizomorphs and the percent infection of trembling aspen, Populustremuloides Michx., stakes used as a bioassay. One year after treatment, crown condition and cambial electrical resistance of trees initially in early stages of crown dieback improved compared with controls. The crown condition of sugar maples previously attacked by the sugar maple borer, Glycobiusspeciosus (Say), did not improve during 5 years of observation, whereas 18% of uninfested trees in similar initial crown condition did improve. Sugar maple borer was more abundant in declining trees [Formula: see text] than is typical of nondeclining infested trees [Formula: see text]. Declining trees had more sugar maple borer damage than apparently healthy trees (no evidence of crown dieback). The borer and the fungus are important contributing agents that prevent recovery of many declining sugar maples.
Measuring resistance of chestnut trees to chestnut blight
Authors: Anagnostakis Sandra L.
Published: September 2007

Four species of chestnut trees and four kinds of hybrids were inoculated with two virulent strains of the chestnut blight fungus (Cryphonectriaparasitica (Murr.) Barr). Rate of canker expansion was measured over 114 days (June–September), and rate change was used as a quantitative assessment of individual tree resistance. Cankers on two typical American chestnut trees (Castaneadentata (Marsh.) Borkh.) expanded at a rate of 1 mm/day. Expansion rates on Chinese chestnut (Castaneamollissima Blume) ranged from 0.2 to 0.6 mm/day, and the rates on two Japanese chestnut trees (Castaneacrenata Siebold & Zucc.) were 0.08 to 0.2 mm/day. Our single Henry chestnut (Castaneahenryi (Skan) Reh. & Wilson) tree allowed rates of 0.3 and 0.8 mm/day. Most rates on American–Chinese and Japanese–American hybrids were from intermediate between rates on Asian and American trees to near the rates on American trees. However, a first-generation backcross of Chinese–American × American only allowed expansion rates of 0.3 and 0.4 mm/day, similar to the lowest rates on Asian trees.
Conversion of dense lodgepole pine stands in west-central British Columbia into young lodgepole pine plantations using prescribed fire. 1. Biomass consumption during burning treatments
Authors: Blackwell B. , Feller M.C. , Trowbridge R.
Published: September 2007

The ecological effects of different treatments used to convert dense Pinuscontorta var. latifolia Engelm. stands into young P. contorta plantations are determined. The treatments used were felling the trees with a bulldozer and either broadcast burning the slash or bulldozing the slash into windrows, which were then burned. Burns were conducted under different fuel moisture conditions and state of fuel curing to achieve four classes of fire severity. The preburn surface fuel load was relatively high due largely to fallen dead woody materials (10−21 kg/m2). The biomass of the forest floor (5−10 kg/m2) was similar to that of the tree slash (5−13 kg/m2), while the understory vegetation was a minor component (0.3−0.5 kg/m2). The quantity of slash and understory vegetation consumed by burning increased with the preburn mass of the same components. Forest floor consumption depended primarily on the preburn forest floor mass for windrow burns and on forest floor moisture content as well as preburn forest floor mass for broadcast burns. Fire severity generally did not have a strong influence on biomass consumption, although it did significantly influence forest floor consumption. There was a general trend, however, of increasing biomass consumption in broadcast burns with increasing fire severity. Windrow burning consumed more biomass than did broadcast burning under similar weather and fuel moisture conditions. Windrow burning resulted in uniformly high biomass consumption that was relatively independent of fuel moisture over the wide range of fuel moistures studied.
Effects of ozone and simulated acidic precipitation on above- and below-ground growth of loblolly pine (Pinustaeda)
Authors: Qiu Z. , Chappelka A.H. , Somers G.L. , Lockaby B.G. , Meldahl R.S.
Published: September 2007

Loblolly pine (Pinustaeda L.) seedlings from two families differing in ozone sensitivity were exposed to four ozone concentrations (charcoal-filtered (subambient ozone concentration), nonfiltered (ambient ozone concentration), non-filtered × 1.7, and nonfiltered × 2.5) and three levels of acidic precipitation (pH = 3.3, 4.3, and 5.3) in modified open-top chambers for one growing season at Auburn, Alabama. Seedlings were planted in the ground in root-exclusion tubes that isolated root systems of individual seedlings. Foliage, stem, and root biomass, three-dimensional root surface area (root surface area × π; in cm3), final height, and groundline diameter were recorded and analyzed. Foliage dry matter and root surface area decreased and root to shoot ratio significantly increased with increasing ozone concentrations for the ozone-sensitive family. There were no significant pH effects for this family. No significant differences in either ozone or pH treatments occurred for the ozone-tolerant family. The possible implications on long-term effects of ozone and acidic precipitation on loblolly pine growth are discussed.
Productivité de pessières noires boréales régénérées par marcottage à la suite de vieilles coupes totales au Québec
Authors: Paquin Raynald , Doucet René
Published: September 2007

Five black spruce (Piceamariana (Mill.) B.S.P.) stands originating from clear-cutting between 1924 and 1941 in the Baie-Comeau area of Quebec were studied to determine post-harvest growth. The analysis revealed that most stems originated from layers released by clear-cutting of the main stand. Present stem height is closely related to height at time of release: stems that were taller at release are now generally dominant or codominant in the main canopy and tend to contribute more to merchantable stand volume. Volume production of these stands is comparable to that of better sites of normal yield tables for black spruce. This means that black spruce layers occupying the understory, including stems a few meters high, can lead to the etablishment of productive stands when released by clear-cutting of the main stand. Despite the relatively advanced age of stems, decay does not seem to be more prevalent in these stands than in stands originating from seed, whose total age would be equivalent to release age of the stands studied.
Midwinter weight gain of excised white spruce branchlets at the northern tree line
Authors: Scott Peter A. , Hansell Roger I.C.
Published: September 2007

A net weight gain was recorded during midwinter abrasion experiments with 3-year-old branchlets excised from tree-line white spruce (Piceaglauca (Moench) Voss). Subsequent experimentation with 96 two-year-old branchlets, including 6 controls, confirmed an average weight gain of approximately 8% even though there was considerable needle loss from abrasion by wind-driven snow particles. A statistically significant pattern of weight gain was evident, with the largest branchlets, which had the lowest surface area to volume ratio, showing the least gain. A similar pattern in weight loss during thawing and drying of some of the branchlets indicates that the weight gain is apparently the result of rehydration during an unusual winter warming, when the ambient temperature exceeded −11 °C.
Modifying sexual expression of containerized jack pine by topping, altering soil nitrogen and water, and applying gibberellins
Authors: Fogal W.H. , Coleman S.J. , Wolynetz M.S. , Schooley H.O. , Lopushanski S.M. , Anderson M.L.
Published: September 2007

The numbers of seed strobili and pollen strobilus clusters and the extent of branch terminal growth were determined on 6-year-old containerized jack pine (Pinusbanksiana Lamb.) trees following modification of the soil nitrogen (N) supply (NH4NO3 at 3, 100, or 300 mg N/L; NO3− at 100 mg N/L; or NH4+ at 100 mg N/L in a nutrient solution), soil water supply (soil water potentials above −20 kPa compared with potentials near −70 kPa), and tree crown size (intact trees outside polythene shelters and lightly versus severely topped trees under polythene shelters). These factors were tested with or without biweekly foliar applications of spray solutions containing 400 mg/L of GA4/7. Intact trees outside polythene shelters did not display sexual or growth responses to N or GA4/7 treatments. Seed strobilus production on topped trees under shelters was not influenced by the level of topping or N supply, but it was depressed by low soil moisture potentials and stimulated by GA4/7 with high or low soil water potentials. Pollen strobilus production was depressed by severe topping and by low soil water potential; it was stimulated by GA4/7 on lightly topped trees but not on severely topped trees and by a low (3 mg N/L) N supply. In the year after treatment, terminal growth of a branch from the 2-year-old nodal whorl was not influenced by nitrogen supply or by light topping but it was increased by severe topping; it was increased by GA4/7 treatment if soil water potential was high but not with low water potential; it was depressed by low soil water potential.
Competition for nitrogen between Pinusradiata and pasture. I. Recovery of 15N after one growing season
Authors: Clinton P.W. , Mead D.J.
Published: September 2007

As part of a monthly N fertilizer application program, 15N-labelled fertilizers were applied on one occasion, in spring, to 4-year-old Pinusradiata D. Don growing under different levels of competition. The three competition levels were removal of pasture, simulated grazing, and rank ryegrass–cocksfoot–clover pasture. Pinusradiata assimilated similar quantities of 15N when it was supplied as 15NO3− or 15NH4+ in the simulated-grazing treatment. Removing pasture competition doubled tree 15N, but total uptake into above and belowground components did not exceed 15.4% of the 15N applied. Pasture uptake of 15NO3− and 15NH4+ was not significantly different when recovery in pasture stubble and roots at the final harvest was included with the recovery from all pasture harvests. However, 15NO3− recovery was 40% greater than 15NH4+ in aboveground herbage. Uptake by rank pasture was less than half that of the simulated-grazing treatment. Uptake by artificially grazed pasture did not reduce 15N movement into the P. radiata canopy to the same extent as uptake by rank pasture. However, there was little evidence that the simulated-grazing treatment provided any benefit to tree growth through increased cycling of N or reduced pasture root growth. There were no significant differences in 15N recovery between treatments in the 0–20 cm depth of soil; on average this was 49% of the N applied. Total system recovery was 107, 92, 76, and 71% for the 15NO3−-treated, 15NH4+-treated simulated-grazing, 15NH4+-treated rank-pasture, and no-pasture treatments, respectively. The loss of 15N from the system could not be accounted for by leaching to depths of 60 cm. Hence, in the no-pasture treatment, where the loss of 15N was greatest, 15N loss may have been due to denitrification.
Fine-textured soil bands and oak forest productivity in northwestern lower Michigan, U.S.A.
Authors: McFadden Joseph P. , MacDonald Neil W. , Witter John A. , Zak Donald R.
Published: September 2007

The relationship between fine-textured soil bands and forest productivity was studied by comparing three mixed-oak (Quercusrubra L. and Quercusalba L.) stands that had little or no fine-textured banding with three stands that had bands. The degree to which soil factors could account for differences in productivity between banded and unbanded stands was examined using two methods, one based on field observations (banding codes) and the other based on laboratory textural analysis. Because stand ages were not significantly different, overstory biomass was used as an index of productivity. Mean overstory biomass in the banded stands was 312 Mg/ha, significantly greater than 170 Mg/ha measured in the unbanded stands. Mean percent clay + silt and mean banding code also were significantly higher in banded than in unbanded stands. Linear regression analysis indicated that mean percent clay + silt accounted for 57% of the variation in overstory biomass, whereas mean banding code accounted for 40% of the variation. In the oak stands we studied, variation in productivity can be explained largely by differences in soil texture associated with fine-textured bands. We also found a positive relationship between mean banding code and mean percent clay + silt (r2 = 0.90), which suggests that the field method of quantifying banding can produce values that are highly correlated with soil texture and, by extension, forest productivity.
Regeneration of subalpine fir (Abieslasiocarpa) following fire: effects of climate and other factors
Authors: Little Ronda L. , Peterson David L. , Conquest Loveday L.
Published: September 2007

Subalpine fir (Abieslasiocarpa (Hook.) Nutt.) regeneration following fire was studied at two locations that burned in 1902 northeast of Mount Rainier, Washington. Tree establishment dates were compared with local climatic records using multiple and logistic regression to identify potential relationships between seasonal climate and annual tree establishment. The influence of microsite features on forest regeneration was also explored. Little regeneration occurred in the first 30 years after the fires, and most trees established in the 1950s, 1977, 1983, and 1989. The dominance of trees <50 cm tall at both sites indicates that trees are continuing to establish on these burns. Establishment is positively correlated with warm, dry springs with low snow accumulation, and cool, wet summers with some variation in significant monthly climate between sites. Tree establishment following fire is greater near other trees and woody debris than other microsite features; however, the microsites available and used for tree establisment may change over time as snags fall and trees establish. More than 50% of the recently established trees (<50 cm tall) are located near larger trees and shrubs, and few (<10%) trees are growing in exposed mineral soil. Older trees (≥50 cm tall) are frequently observed near woody debris. The response of subalpine fir regeneration to changes in climate will depend on the magnitude and seasonality of changes in weather, especially during spring. Tree establishment may be enhanced if there is less snow accumulation and a longer growing season. However, warmer, drier summers could result in additional moisture stress to seedlings, especially at sites with high solar radiation (south and west aspects) and well-drained soils.
Composition and development of conifer regeneration in thinned and unthinned natural stands of western hemlock and Sitka spruce in southeast Alaska
Authors: Deal Robert L. , Farr Wilbur A.
Published: September 2007

Natural regeneration of understory conifers was studied in 1988, 9–14 years after thinning of even-aged stands of western hemlock (Tsugaheterophylla (Raf.) Sarg.) and Sitka spruce (Piceasitchensis (Bong.) Carr.) on upland sites in southeast Alaska. Two age-classes of stands were compared: young stands, <30 years old that before thinning had open forest canopies and understories of conifer regeneration, shrubs, herbs, and forbs; and older stands, 31–98 years old, that before thinning had closed forest canopies and little or no understory vegetation. In 1988, dominant understory conifers in young stands were 2–4 m tall, and about the same age as trees in the overstory. In the older stands there was dense new regeneration that germinated 2–3 years after thinning and averaged 0.6–1.5 m tall. Seventy-two to 100% of all regeneration was hemlock. The rest was Sitka spruce. The amount of regeneration increased and the percentage of hemlock decreased with increasing thinning intensity. Thinning of young stands on upland sites appears to benefit understory conifers, which rapidly expand to fill in the available growing space. Heavy thinning in older stands promotes dense germination of understory conifers making it difficult for other understory plants to become established.
A method to adjust simultaneously for spatial microsite and competition effects
Authors: Magnussen Steen
Published: September 2007

A patchy microsite mosaic gives rise to positive spatial correlations among first-order neighbors in field trials. Competition for a resource in short supply tends to enhance size differences among first-order neighbors. Simulation studies demonstrated that positive spatial autocorrelations will seriously inflate family variance components and, thus, the individual narrow sense heritability in sib trials with multiunit plots in randomized complete block designs. Moderate levels of competition between first-order neighbors had the effect of lowering this inflation. Results from simulated single-tree plot designs were never biased. In the absence of strong competition, this design type is clearly preferable. An effective method for adjusting results obtained from multiunit plot designs is presented. Adjusted values of family variances and heritabilities were within 6% of the true values in two of three simulations. Adjustments are based on an iterative nearest neighbor (NN) regression on family values and a NN adjustment of ANOVA residuals. An application of the NN adjustments to height and diameter data in a jack pine (Pinusbanksiana Lamb.) sib test lowered heritabilities of height to the expected level and indicated similar levels of genetic control of the two traits.