bluuebunny/crossref_metadata_2025 huggingface dataset:
Current Status of Vaccines for Schistosomiasis
Authors: McManus Donald P. , Loukas Alex
Published: January 2008

Schistosomiasis, caused by trematode blood flukes of the genusSchistosoma, is recognized as the most important human helminth infection in terms of morbidity and mortality. Infection follows direct contact with freshwater harboring free-swimming larval (cercaria) forms of the parasite. Despite the existence of the highly effective antischistosome drug praziquantel (PZQ), schistosomiasis is spreading into new areas, and although it is the cornerstone of current control programs, PZQ chemotherapy does have limitations. In particular, mass treatment does not prevent reinfection. Furthermore, there is increasing concern about the development of parasite resistance to PZQ. Consequently, vaccine strategies represent an essential component for the future control of schistosomiasis as an adjunct to chemotherapy. An improved understanding of the immune response to schistosome infection, both in animal models and in humans, suggests that development of a vaccine may be possible. This review considers aspects of antischistosome protective immunity that are important in the context of vaccine development. The current status in the development of vaccines against the African (Schistosoma mansoniandS. haematobium) and Asian (S. japonicum) schistosomes is then discussed, as are new approaches that may improve the efficacy of available vaccines and aid in the identification of new targets for immune attack.
Influence of shelter on night temperatures, frost damage, and bud break of white spruce seedlings
Authors: Groot Arthur , Carlson Derek W.
Published: January 2008

Measurements of frost damage and bud-break phenology were made during the spring of 1993 and 1994 on planted white spruce (Piceaglauca (Moench) Voss) seedlings and on trembling aspen (Populustremuloides Michx.) suckers in combination with measurements of minimum air temperature and long-wave radiation in forest openings of different sizes and configurations (1.5-ha clearcut, 9 and 18 m wide strips, 9 and 18 m diameter circular openings and intact forest) near Chapleau, Ontario. The average minimum air temperature during early summer (May–June) decreased linearly as the sky view factor of the forest openings increased. The average difference in minimum air temperature between the forest and clearcut opening was nearly 3 °C for the period, and during clear night sky conditions, this temperature difference approached 6 °C. The difference in minimum temperature between the forest and clearcut during cloudy night sky conditions was slightly greater than 1 °C. Differences in minimum air temperature between the forest and each of the openings increased with decreasing incoming long-wave radiation. The largest differences occurred between the forest and the clearcut with low incoming long-wave radiation (cloudless nights). Minimum air temperatures in the 9-m strip and 9-m circle differed little from minimums in the forest under all long-wave radiation regimes. Moderation of air temperature on clear nights would be best achieved with sky view factors of less than 0.3, implying a maximum strip width of 0.6 tree heights and a maximum patch diameter of 2.2 tree heights. Damage to white spruce seedlings after a frost in the spring of 1993 increased with increasing sky view factor. Nearly 75% of the seedlings in the clear-cut had medium or heavy frost damage, while only 2% of the seedlings in the 9-m circle and forest were frost damaged. Opening size and configuration had little influence on the timing of bud break in either the white spruce seedlings or the trembling aspen suckers.
Selection for biomass production based on respiration parameters in eucalypts: acclimation of growth and respiration to changing growth temperature
Authors: Criddle R.S. , Anekonda T.S. , Sachs R.M. , Breidenbach R.W. , Hansen L.D.
Published: January 2008

This paper examines the relation between respiratory physiology and growth rate and the effects of environment on this relation for the purpose of developing means for accelerating and improving selection of trees for biomass production. The relations among biomass production, respiratory metabolism, and growth temperature in controlled environments were determined for three Eucalyptus genotypes (clones). Eucalyptuscamaldulensis 4016, E. camaldulensis C11, and Eucalyptusgundal (Eucalyptusgunnii × Eucalyptusdalrympleana hybrid) GD1 were selected for this study because of known qualitative differences in their field growth responses to temperature. These clones were grown in controlled environments at three temperatures. Measurements were made of growth rate, metabolic heat rate, and dark CO2 production rate for plants grown at each of the three temperatures. This allowed determination of respiration rates of plants originally adapted for growth in different climates, but acclimated during growth at three different controlled temperatures, and also determination of respiration changes resulting from short-term changes in temperature. Growth rates of the three clones differed in their patterns of response to changes in growth temperature. For example, C11 grew most rapidly at the highest temperature, while GD1 was slowest at high temperature. Metabolic rates and the temperature dependence of metabolic rates of the clones differed and the pattern of differences changed when plants became acclimated to growth at different temperatures. Changes in metabolic properties of the three clones with growth and measurement temperatures are consistent with the growth rate changes. In general, increased growth rate was accompanied by increased respiration rate measured either as heat rate or as rate of CO2 production. Growth rates were inversely related to two measures of metabolic energy use efficiency. Growth rates decreased as values of heat loss per gram dry weight produced and values of heat loss per mole of CO2 produced increased. Recognition of these relations between growth rate and respiration parameters at different temperatures in controlled environement may allow prediction of relative growth rate performance of Eucalyptus clones over a range of growth climates.
Effect of thinning on the foliar nutrient status of Scots pine stands on drained boreal peatlands
Authors: Hökkä Hannu , Penttilä Timo , Hånell Björn
Published: January 2008

Foliar responses to thinning in midrotation stands of Scots pine (Pinussylvestris L.) were studied in six thinning experiments (0–50% of basal area removed) established on drained peatlands in northern Finland and southern Sweden. The trophic level of the sites varied from ombrotrophic to meso-eutrophic. Needle sampling and analyses were carried out on individual trees of dominant and suppressed canopy layers. The variation in the needle dry mass and in the element concentrations and contents, calculated as plot means, was explained by thinning treatment, blocking by site groups and randoming blocking within the site. Thinning increased foliar concentrations of P, needle size, and contents of N, P, and K in all the canopy layers. It was concluded that thinning improved the foliar nutrient status by reducing the competition for nutrients.
Measurement error causes bias in site index equations
Authors: Goelz J.C.G. , Burk T.E.
Published: January 2008

Modeling height in the context of site index involves two processes: (i) estimating height at base age (site index), given height at some other age, and (ii) estimating height at some desired age given height at base age. When these two processes are modeled by individual functions for each process, height is assumed to be measured without error when on the right-hand side of the equation, but possessing error when on the left-hand side of the equation. This assumption causes a bias in the parameters of the site index curves. The bias in the estimated parameters is evident in the magnitude of the curves and in the shape of the curves, the typical change of shape of the curves from low site index to high site index is underestimated. An ad hoc method is presented that solves the problem. The ad hoc method is conceptually related to methods used in linear regression and to maximum likelihood estimation in a measurement errors problem context. A general measurement errors model is presented as an alternative. The measurement errors model requires an independent estimate of measurement error.
Freezing dehydration damages roots of containerized Scots pine (Pinussylvestris) seedlings overwintering under subarctic conditions
Authors: Sutinen Marja-Liisa , Mäkitalo Kari , Sutinen Raimo
Published: January 2008

The survival of conifer roots under winter conditions is not well understood. The effect of long-lasting freezing at extremely low temperatures on the survival of the roots of Scots pine (Pinussylvestris L.) seedlings from a timberline seed source was studied. One-year-old containerized seedlings were kept for 4 months under winter conditions typical of the subarctic region. The freezing treatment was accelerated by preventing snow accumulation on half of the seedlings. The proportion of living root tissue and the amount of sugars (glucose, fructose, and sucrose) and starch in the needles and roots were measured at weekly intervals. The temperature within the growth medium without snow cover fell on a number of occasions to −30 °C. The lowest temperature recorded within the snow-covered growth medium was −20 °C. The sugar content increased faster and to a higher level in the seedlings without snow cover, but it did not affect root survival. The proportion of living root tissue without a cover of snow decreased by 80% by the end of December, and the roots were completely injured by the end of February. There was only a slight decrease in the proportion of living roots among seedlings covered by snow. The reduced root survival was not directly related to exposure to the lowest freezing temperatures; instead, it was manifested some weeks after exposure. This suggests that dehydration resulting from prolonged severe freezing caused root damage. The presence of a cover of snow reduces subzero temperature extremes and the severity of dehydration; together, these result in enhanced root survival.
Spatial heterogeneity of a Scots pine canopy: an assessment by hemispherical photographs
Authors: Walter J.-M.N. , Himmler C. Grégoire
Published: January 2008

To characterize the spatial heterogeneity of forest canopies at various scales, leaf area index (LAI) and transmission of photosynthetically active radiation (PAR) were measured. Six Scots pine (Pinussylvestris L.) stands, representing typical growth stages, from regeneration to mature forest, were selected for study, in Alsace, France. In each stand, hemispherical photographs were taken near the ground at regular intervals along transects, digitized, and analyzed. Gap fractions were inverted to provide estimates of LAI. Light transmission through the canopy was calculated by means of a numerical method. In a typical mature stand, the variability of LAI and PAR transmittance was spatially assessed by means of semi-variograms; spatial autocorrelation occurred up to about 10 m. This result provided a guide to optimize the sampling at the forest mosaic level. For the whole forest, LAI ranged from 1.6 to 7.8; PAR transmittance ranged from 0.02 to 0.59 under overcast sky and from 0.01 to 0.48 under clear sky (June). Maximum variability was found in the youngest stand, owing to a row effect, and in the two oldest stands, which include Norway spruce (Piceaabies (L.) Karst.) patches in the understory. Intermediate variability characterized maturing stands. Methodological problems concerning LAI and PAR transmission estimated by indirect approaches are discussed, as well as the spatial structure of these variables.
Catalase isozymes as biochemical markers of different developmental stages in cypress (Cuptessussempervirens)
Authors: Racchi M.L. , Chiusi A.P. , Giannini R.
Published: January 2008

The expression of catalase isozymes has been investigated to define the different developmental stages of cypress (Cupressussempervirens L). To examine the temporal pattern of catalase expression during development, catalases in dry seeds, young embryos, and different tissues of the mature plant were characterized by native polyacrylamide gel electrophoresis. The data indicated the presence of two patterns of expression: one specific to the seed and young embryo and another for the mature plant. Defined isoforms were specific to each developmental time. The results indicated that different catalase isozymes are developmentally expressed. Consequently the changes in their expression pattern can be used to define the development stages of the tree.
Acorn production by oaks in central coastal California: influence of weather at three levels
Authors: Koenig Walter D. , Knops Johannes M.H. , Carmen William J. , Stanback Mark T. , Mumme Ronald L.
Published: January 2008

Mean annual acorn crop size of oaks in central coastal California correlated with weather for four of five species. For the deciduous Quercuslobata and Quercusdouglasii, larger crops were produced in years when April temperatures were warmest, while for the evergreen Quercusagrifalia and Quercuschrysolepis, crops were larger when there was more rain one and two years prior to the year when acorns were produced. No correlations were found between weather and mean annual acorn production by Quercuskelloggii. Within years, individual Q. douglasii that flowered during periods of greater solar radiation produced more acorns, and during 1 of 5 years individual Q. lobata and Q. agrifolia produced larger crops when they flowered during warm, dry periods. These results indicate that conditions favorable for pollination and fertilization strongly enhance mean annual acorn production in Q. lobata and Q. douglasii and may have an effect on differences in acorn crop size among individual Q. lobata, Q. douglasii, and Q. agrifolia. Mean annual acorn crops of these three species were significantly concordant among three sites in central coastal California 300 km apart. Weather conditions were also significantly correlated, especially annual rainfall and mean April temperatures. Thus, the environmental factors that have the strongest influence on mean annual acorn production within a site are also those that are the most geographically concordant. However, we found no relationship between environmental factors and differences in mean annual acorn production by these same three species at the three sites.
Detection of observer bias in ongoing forest health monitoring programmes
Authors: Strand Geir-Harald
Published: January 2008

This article describes a method for detecting bias between observers in monitoring programmes where crown density is used as the indicator of forest health. The method concentrates on trees where the surveyor team has changed from year to year and compares the changes reported by each separate pair of observers. It shows that observer bias is present in the Norwegian monitoring programme. Observer bias can give an artificial impression of geographical patterns if surveyors are allowed to operate regionally and may also result in inconsistent or even false reports about change in crown density. Monitoring programmes cannot differentiate between effects of observer bias and real environmental changes unless the observers are assigned to monitoring sites on a permanent basis.
Species composition of old-growth and riparian Sitka spruce–western hemlock forests in southeastern Alaska
Authors: Hanley Thomas A. , Hoel Terje
Published: January 2008

We studied six 1.2-ha stands, two each of three types of forest: (1) old-growth, riparian floodplain forest, (2) old-growth, upland forest, and (3) 40-year-old, red alder (Alnusrubra Bong.) riparian forest originating after clear-cut logging of floodplain forest. Sitka spruce (Piceasitchensis (Bong.) Carrière) dominated the old-growth riparian stands and shared dominance with western hemlock (Tsugaheterophylla (Raf.) Sarg.) in the uplands. Regeneration was predominantly spruce in the alder riparian, spruce and hemlock in the old-growth riparian, and hemlock in the upland stands. Total understory biomass and ground cover did not differ significantly between forest types, but species-specific biomasses did differ (P < 0.05). Understory of the upland forest was dominated by early blueberry (Vacciniumovalifolium Sm.) and Alaska blueberry (Vacciniumalaskensis How.), while that of both riparian types was dominated by devilsclub (Oplopanaxhorridum (Sm.) Miq.). Other species-specific differences occurred in forbs (three species) and mosses (three species). Contrary to typical stand age–understory relations in upland conifer forests of the region, the understory of the 40-year-old red alder stands was very species rich and productive.
Incorporating predictions into an annual forest inventory
Authors: Deusen Paul C. Van
Published: January 2008

Growth modeling of forests at the individual tree and stand levels is a highly refined procedure for many forest types. A method to incorporate predictions from such models into a forest inventory system is developed. Variance components from the actual measurements and from the predicted measurements are used to estimate the variance of the combined predicted value. The only assumption required to justify this method is that the model estimate has a bias that does not change from one time period to the next. The estimation procedure proposed here can also incorporate remotely sensed information via a regression estimator.
Prediction of throughfall quantities under different forest stands
Authors: Mahendrappa M. K. , Kingston D. G. O.
Published: January 2008

The quantitative distribution of throughfall in fertilizer-treated and control plots under six softwood and three hardwood stands and rainfall in open areas close to these stands were intensively measured during 1977–1978. Standard rain gauges and improvised funnel-type collectors were used for measuring both throughfall and rainfall in the open. The improvised funnel-type collectors with an orifice smaller than that of the standard rain gauges were found to be suitable for accurately measuring quantities of both open rainfall and throughfall. Simple linear regression models of the form Y = b − a were sufficient to predict throughfall quantities (Y) based on rainfall (X) measurements. The relationship between the quantities of throughfall and rainfall was highly significant in each case. Application of urea at a rate of 225 kg N ha−1 did not affect either the slope (b) or the elevation (a) of the relationship. No significant differences were found between the relationships calculated for 1977 and 1978 for any species except balsam fir (Abiesbalsamea (L.) Mill) and larch (Lurixlaricina (Du Roi) K. Koch). The difference for balsam fir was probably a result of extensive defoliation by the spruce budworm (Choristoneurafumiferana (Clem.)). In most cases, values of the slopes (b) of the models for the different species were not significantly different. The nine species did, however, differ significantly from one another in terms of the minimum quantity of rain (a/b) that must fall before throughfall was measurable in the collectors.
Resin acid, turpentine, and caloric content of paraquat-treated slash pine
Authors: Kossuth Susan V. , Roberts Donald R. , Huffman Jacob B. , Wang Shih-Chi
Published: January 2008

Slash pines (Pinuselliottii Engelm.) were injected with 2% paraquat cation (weight/weight basis) and harvested after 24 months. Each stem was cut into three bolts and the amounts of resin acids and of turpentine, the net energy value, and the moisture content were measured. In the lower bolt, adjacent to the treated zone, a 984% increase in resin acids and a 2460% increase in turpentine were found. Averaged over the entire tree stem (three bolts) resin acids increased 407% and turpentine 784%. Moisture content was reduced 53.2% in the lower bolt and 28.4% in the middle bolt and increased 10% in the upper bolt. Turpentine amounts from treated and untreated trees were qualitatively similar and had an average heating value of 10 369 cal/g (1 cal = 4.1868 J). Lower moisture and increased resin of the treated trees increased the caloric content of the lower 152-cm bolt by 33.1% above controls and of the whole tree stem by 12.7% above the controls.
Gap dynamics in a hemlock–hardwood forest
Authors: Hibbs David E.
Published: January 2008

The dynamies of small openings in a hemlock–hardwood stand at the Harvard Forest, Petersham, Massachusetts, were studied. Rates of lateral growth of canopy tree species into openings ranged from 6 to 14 cm/year with a maximum of 26. Red oak (Quercusrubra L.) (RO) had the highest rate of lateral expansion. In small openings (r < 0.25 × tree height), regenerating species ranked by rate of height growth were as follows: black birch (Betulatenta L.) (BB) > red maple (Acerrubrum L.) (RM) > yellow birch (B. alleghaniensis Britton) (YB) > hemlock (Tsugacanadensis (L.)Carr.) (HK) = red oak; in moderate size openings (r = 0.25 to 0.5 × tree height), the ranking was birches = RM > RO > HK; in open grown even-aged stands, the ranking was RO > BB = RM = YB > paper birch (B. papyrifera Marsh.) [Formula: see text] HK. A comparison of rates of height growth with opening closure rates indicates that tree reproduction is not successful in openings of less than about 0.5 × tree height in diameter. This is primarily because small openings close quickly by lateral growth of the surrounding canopy trees and is not simply a factor of changes in rates of height growth with opening size.
Control of Phellinusweirii in Douglas-fir stumps by the fumigants chloropicrin, allyl alcohol, Vapam, or Vorlex
Authors: Thies W. G. , Nelson E. E.
Published: January 2008

Four fumigants (chloropicrin, allyl alcohol, Vapam, and Vorlex), applied to holes in Phellinusweirii (Murr.) Gilb. infested Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stumps, eliminated the fungus from the stumps and most roots. No significant difference in effectiveness was noted among the chemicals. Stump size and condition were probably the factors which most influenced the effectiveness of the treatments. Fumigants merit further study for eliminating P. weirii from stumps and roots of Douglas-fir to reduce losses from this fungus.
Effect of accelerating growth on flowering in lodgepole pine seedlings and grafts
Authors: Wheeler N. C. , Ying C. C. , Murphy J. C.
Published: January 2008

Seedlings and grafts from lodgepole pine (Pinuscontorta var. latifolia Dougl.) plus-tree selections in British Columbia were established and maintained in the greenhouse under 24-h photoperiod for 6 months. Subsequently, seedlings were outplanted in the nursery and grafts in a breeding orchard at Red Rock Research Centre. In the 5th year from seed (1980), the proportion of flowering trees and the average number of seed cones per flowering tree were roughly six times greater for accelerated growth seedlings (81%, 18 flowers/tree) than for controls (12%, 3.6 flowers/tree). Differences in pollen cone production were of similar magnitude. Flower enhancement in seedlings carried over into the next year. Grafted trees were considerably less productive than seedlings. At age 5 a mean of four female strobili were produced on 77% of treated grafts compared with 1.6 strobili on 36% of untreated controls. These values decreased slightly in 1981. Pollen production was yet to be observed on grafted materials. While the superiority in height of accelerated seedlings relative to controls has steadily decreased since time of establishment, large differences in number of branches per tree and biomass remain. Root systems of accelerated seedlings generally were excessively pot-bound, resulting in considerable root grafting after outplanting. The possible causes of increased flower production in accelerated growth trees are briefly discussed. The production of both pollen and seed cones in numebrs large enough to support a modest breeding scheme greatly increases the opportunity for rapid generation turnover in forest trees such as lodgepole pine and permits greater flexibility in planning a long-term tree improvement program.
Decay and canker formation by Phellinuspini in white and balsam fir
Authors: Blanchette Robert A.
Published: January 2008

Phellinuspini (Thore ex Fr.) A. Ames var. cancriformans Larsen, Lombard, Aho and P. pini (Thore ex Fr.) A. Ames var. pini on white fir (Abiesconcolor (Gord. and Glend.) Lind. and balsam fir (A. balsamea Mill.), respectively, initiated a nonspecific host response in phloem and xylem. Light and scanning electron microscopy were used to elucidate canker formation and morphological characteristics of decayed wood. In phloem, cells occluded around infected areas but the fungus was not confined. Barrier zones in xylem consisted of numerous tangential series of resin ducts, parenchyma cells, and twisted tracheids. Although many barrier zones are formed, often several within one annual ring, the fungus was not effectively compartmentalized. The successful penetration or evasion of barrier zones resulted in canker enlargement by both fungi. Phellinuspini var. cancriformans caused a typical white rot decay of heartwood in white fir whereas P. pini var. pini in balsam fir caused a selective delignification of wood.
Water relations, growth, and survival of root-wrenched Douglas-fir seedlings
Authors: Duryea Mary L. , Lavender Denis P.
Published: January 2008

Root wrenching in the nursery was investigated in relation to Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedling growth and survival under field conditions. Immediately after wrenching, seedlings had lower plant water potential and leaf conductance of water vapor than unwrenched seedlings. At lifting, shoots of wrenched seedlings were shorter, lighter, and of smaller diameter than those of unwrenched seedlings. Seedlings from four of six seed sources tested had significantly lighter taproots after wrenching, but lateral root and total root weights were not significantly different. Mainly because of lighter shoots, wrenched seedlings had smaller shoot–root ratios than controls. After field planting, wrenched and unwrenched seedlings at a droughty site did not differ in leaf conductance or plant water potential, and throughout exposure to a simulated summer drought in pots, all seedlings showed equal plant water potential, leaf relative water content, and seedling condition. However, wrenched seedlings of four seed sources did not set a bud as quickly during drought and had significantly fewer active roots than unwrenched seedlings. In no case did root wrenching improve growth or survival in the field, and among four seed sources shoot growth was significantly less than that of unwrenched seedlings after 3 years.
Specific gravity and tracheid length variation of white spruce in Alberta
Authors: Taylor Fred W. , Wang Eugene I. C. , Yanchuk Alvin , Micko Michael M.
Published: January 2008

Specific gravity and tracheid lengths were measured for increment cores from 10 trees in each of four selected white spruce (Piceaglauca (Moench) Voss) stands in Alberta. The data show large specific gravity differences among sample stands and from tree to tree within stands. Longer tracheids were found in mature wood of trees grown in the more northern stands sampled. A few trees were intensively examined to determine the variation of properties within the stem. The complex variation patterns from pith to bark and stump to crown are reported with comments on the importance of these variation patterns to breeding programs for the improvement of the wood properties. A somewhat unusual finding was that white spruce produces wood in top logs that is of equal or greater specific gravity and tracheid length than wood produced in butt logs.
Growth of lodgepole pine and white spruce in the central interior of British Columbia
Authors: Eis S. , Craigdallie D. , Simmons C.
Published: January 2008

Height, diameter, volume growth, crown width, and stocking of lodgepole pine (Pinuscontorta Dougl.) and white spruce (Piceaglauca (Moench) Voss) were studied on the three most common forest sites in the central interior of British Columbia, to estimate their potential growth and their suitability for pure or mixed stands in managed second-growth forests established by planting. Spruce only should be planted on moist to wet Alluvium sites; both species appear to be equally suitable on moist Aralia sites, and pine only should be planted on dry to moist Cornus–Moss sites. In mixed forest, suppressed spruce will have little volume at the time of pine harvest. In general, managed, fully stocked second-growth forests should produce greater volume per hectare than the present natural, unmanaged forests.
Population structure, genic diversity, and morphological variation in Pinuscontorta Dougl.
Authors: Wheeler Nicholas C. , Guries Raymond P.
Published: January 2008

Lodgepole pine (Pinuscontorta Dougl.) occupies a large and ecologically diverse range in western North America. The species is generally recognized as consisting of four subspecies, three of which are widespread and the fourth endemic to the north coast of California. Geographic isolation of subspecies is nearly complete although gene flow may occur in certain instances. Moderate heterozygosity estimates (0.10–0.14) and low standard errors of the estimate (0.02–0.04) were obtained for all populations of lodgepole pine and are comparable with other recent studies of conifers that based estimates on 20 or more loci. The distribution of allozyme variation indicates that very little population differentiation has occurred. Approximately 91% of the allozyme variability resides within populations, with 3 and 6% distributed among subspecies and among populations, respectively. The extent of population differentiation is far less than that observed for many herbaceous plants but similar to reports for other conifers. In contrast, a large proportion of morphometric variation in lodgepole pine cone and seed traits is distributed among subspecies (38%) and among populations within subspecies (19%). This may be attributed to the effects of strong selective pressures acting on important reproductive structures and to the conventional methodology for analyzing morphometric variation. The present study confirms, with minor exceptions, an earlier taxonomic treatment of lodgepole pine. Notably, the assignment of lodgepole pine in the Cascade Range of southern Oregon to ssp. murrayana is probably inappropriate. While morphological data suggest a close affinity to ssp. murrayana, allozyme data suggest that populations in this area should be assigned to ssp. latifolia.
Effects of sulfur dioxide on water relations of hybrid poplar foliage and bark
Authors: Biggs Alan R. , Davis Donald D.
Published: January 2008

Hybrid poplar cuttings were exposed to 0.25 ppm SO2 for 72 h/week for 14 consecutive weeks in 1979. In 1980, a second set of cuttings was exposed to 0.12 ppm SO2 for 72 h/week for 6 consecutive weeks. Foliar and bark water potential, osmotic potential, and the pressure component, as well as leaf conductance, were determined during or following exposure and compared with data from unexposed control plants. Leaf conductance was stimulated during 72-h exposures to 0.25 ppm SO2. Six 72 h/week exposures to 0.12 ppm SO2 had no effect on conductance, but induced changes in foliar water potential and osmotic potential.
Decomposition of red spruce and balsam fir boles in the White Mountains of New Hampshire
Authors: Foster Jeffrey R. , Lang Gerald E.
Published: January 2008

Decomposition rates for red spruce (Picearubens Sarg.) and balsam fir (Abiesbalsamea (L.) Mill.) boles on the forest floor were determined for midelevation forests of the White Mountains from a chronosequence of previously logged stands. Density changes in wood and bark were described using a negative exponential model, yielding decay constants of 0.033 and 0.029/year for spruce and fir wood, respectively. The two species were not statistically different in terms of mass loss. Bole diameter had no influence on the decay rate of red spruce. Fir boles in midelevation forests decayed significantly faster than those in high-elevation forests measured in another study. Net accumulation of N, P, Ca, and Mg occurred in the wood of both species. N accumulated in bark, but P, Ca, and Mg behavior was variable. Na and K behavior was similar in the wood and bark of both species, with Na release concomitant with mass loss, while K was lost faster than mass. C:N ratios declined, and N:P ratios converged on a value of ca. 20, in the wood and bark of both species.
Interaction of soil pH and genotype on growth and nutrient uptake of sycamore seedlings
Authors: Pope P. E.
Published: January 2008

Seedlings from four families of American sycamore (Platanusoccidentalis L.) were grown in a glasshouse for 16 weeks in a Groseclose silt loam soil (Typic Hapludults) in which the soil reaction (pH) had been adjusted from 6.20 to 4.25, 5.50, 6.75, or 8.00 by the addition of Al2(SO4)3 or CaCO3. On the average, seedling height and total dry weight increased with increasing soil reaction to pH 6.7 and then declined. Percentage of foliar P, K, and Ca was largest at a soil pH of 5.5 and declined with an increase or decrease in soil reaction. Foliar P, K, and Ca content is highly correlated with soil pH, seedling total dry weight, and available soil nutrients. Growth of seedlings from individual families, in response to alterations in soil pH, is variable, but the data suggest certain families exhibit significantly greater growth and nutrient uptake than others at soil pH values below 6.8. This fact may be of prime concern in hardwood seedling nursery production, where specific families are being grown, and in the evaluation of growth responses in tree improvement programs.
Total biomass and biomass production of Pinusroxburghii trees growing in all-aged natural forests
Authors: Chaturvedi O. P. , Singh J. S.
Published: January 2008

Detailed morphometric measurements for individual trees in an age series (16–128 years) of P. roxburghii Sarg were carried out. The dry weight of each component of the tree increased with age and total aboveground biomass in a 128-year-old tree was 1939 kg. Satisfactory allometric equations relating biomass of different components with circumference at breast height (cbh) and square diameter × height (d2h) were developed. The error in estimates was lower when the independent variable included tree height. Within an individual tree the biomass of bole increased downwards and the canopy of the tree was concentrated towards the upper part of the tree. The intercomponent biomass relationships were also significant, and the resulting allometric equations carried less error than the equations using cbh as the independent variable. The cumulative dry matter produced by a sample tree within its lifetime was much greater than the respective current biomass. The largest proportion of the production was accounted for by the tree crown and fine roots, while the largest biomass resided in the bole. The maximum current biomass increment was attained at the age of 39 years. The mean annual production increased with age except for bole and root system where it first increased and then attained a constant value after 61 years. The relationships of bole and shoot production per annum to total leaf area and fine roots for different age periods indicated a significant spurt of activity during 36–39 years and a secondary limited spurt during 97–103 years in the life history. The production of nonphotosynthetic components was significantly related with the leaf area and with foliage production.
The SBBB distribution: a potentially useful trivariate distribution
Authors: Schreuder Hans T. , Bhattacharyya Helen T. , McClure Joe P.
Published: January 2008

The proposed SBBB distribution allows for a more complete summarization of stand structure data than has been possible in forestry until now. For two data sets constructed out of a large loblolly pine data set to resemble possible plantations, the univariate SB and the trivariate SBBB distributions fit the data reasonably well as measured by χ2. The median regression of volume in terms of diameter and height gave results almost as good as the standard combined variable model. Computer programs needed to implement the system are available.
Nitrogen fixation and acetylene reduction in decaying conifer boles: effects of incubation time, aeration, and moisture content
Authors: Silvester Warwick B. , Sollins Phillip , Verhoeven Thomas , Cline Steven P.
Published: January 2008

Free-living microaerophiles fixed 15N2 and reduced acetylene in fallen tree boles at two old-growth Pseudotsugamenziesii stands in western Oregon. Acetylene reduction was most rapid under an atmosphere of 2–10% O2, whereas under prolonged anaerobic conditions it was at or below detection limits. Acetylene reduction rates increased up to fourfold during long-term incubations in acetylene (> 12 h). Ratios of acetylene reduction to N2 fixation frequently exceeded 6.0 during such long-term incubations but averaged 3.5 when samples were incubated < 7 h; consequently, long-term incubation of low-activity material in acetylene should be avoided. A preliminary survey indicated that N2 fixation by free-living organisms in fallen boles was less than other potential N inputs to fallen boles and to the forest ecosystem.
Natural hybridization between Populusalba L. and the native aspens in southeastern Michigan
Authors: Spies Thomas A. , Barnes Burton V.
Published: January 2008

The objective of the study was to determine the abundance, pattern of occurrence, and ecology of natural hybrids between the introduced European white poplar, Populusalba L., and the native North American aspens, Populusgrandidentata Michx. and P. tremuloides Michx., in southeastern Michigan. A systematic search was made for P. alba and its hybrids in parts of Washtenaw, Livingston, and Jackson counties. Twenty-seven P. alba clones were located; all were female. Forty-one hybrids between P. alba and P. grandidentata and two hybrids between P. alba and P. tremuloides were located. The mean density of all hybrids was one per 898 ha. Eighty-one percent of the hybrids occurred in groups of two or more and 91% were located within 1.6 km of a P. alba tree. Hybrids occurred exclusively on disturbed sites and across a wide range of moisture regimes. Most hybrids became established between 1930 and 1945, a time period when many farms were abandoned in southeastern Michigan. No effective phenological barrier to continued hybridization or backcrossing was found. The absence of hybrid establishment in the last 30 years was attributed to reduction of suitable seed germination sites in the vicinities of P. alba trees due to reduced human activity and progressing plant succession.
The use of ground flora to indicate edaphic factors in upland ecosystems of the McCormick Experimental Forest, Upper Michigan
Authors: Pregitzer Kurt S. , Barnes Burton V.
Published: January 2008

Groups of ground-flora species indicating similar habitat conditions, termed ecological species groups, were studied over the rather narrow range of upland environmental conditions of the Cyrus H. McCormick Experimental Forest, north-central Upper Michigan, United States. Nonparametric and multivariate statistical techniques were used to analyze frequency of occurrence data and contrast the relative indicator value of the groups and species. Species distributions were finely adapted to the local environmental situation. It was possible to identify specific soil drainage, texture, and fertility levels using the ecological species groups with a known probability of error. For example, presence of the Osmunda species group indicated a 90% probability of soil mottling within the upper 40 cm. By observing the presence and absence of the Clintonia and Osmunda species groups it was possible to classify soil drainage (moist conditions) at the 5% level of significance. Similarly, presence of the Viola species group indicated significantly higher soil pH and total nitrogen levels. The combined approach of studying species distributions along single- and multi-factor environmental gradients facilitated understanding of the specific indicator value of the individual ecological species groups. Results demonstrate the ability of the groups to speed the process of soil and site mapping. Because of the demonstrated specificity of species and changes in soils, climate, and composition from place to place, it is probably necessary to systematically reaffirm specific plant-environment relationships when using plants as indicators of forest potential.
Radial growth reductions of Pinusstrobus L. correlated with foliar ozone sensitivity as an indicator of ozone-induced losses in eastern forests
Authors: Benoit L. F. , Skelly J. M. , Moore L. D. , Dochinger L. S.
Published: January 2008

A study of the radial increment growth of native eastern white pine (Pinusstrobus L.) evaluated the possible effects of oxidant air pollution (primarily ozone) in long-term growth of forest species in the Blue Ridge Mountains of Virginia. Ten plots of three white pines of reproducing age (one each classified as tolerant, intermediate, and sensitive to ozone on a foliar basis) were sampled. Plots were dispersed over 446 km from the northern end of the Skyline Drive in Shenandoah National Park to the southern most part of the Blue Ridge Parkway in Virginia. Mean annual radial increment growth of the ozone sensitive trees was significantly smaller (P = 0.01) than that of tolerant trees for the period 1955–1978. Mean increment growth of all trees, regardless of their sensitivity to ozone, decreased during the period. Precipitation was positively correlated with radial growth in all sensitivity classes prior to 1964, but negatively correlated after 1964.
Soil fertility after logging in the northern Rocky Mountains
Authors: Stark N.
Published: January 2008

Measurements of dry biomass, the concentration of 10 biologically essential ions and other data from compartments of a Douglas-fir – western larch (Pseudotsugamenziesii (Mirb.) Franco – Larixoccidentalis Nutt.) forest were used to study the nutrient impacts of various harvest treatments. Precipitation additions about equalled leaching losses as has been shown elsewhere. Any ions lost in harvest must be replaced by available ions in the soil root zone and ions recycled from decay above and below ground. Conventional harvest of wood >7.6 cm removes about 1% of the total ecosystem cations. Data show that decay and available and accessible soil ions could easily replace the ions lost in a single rotation with conventional harvest. Total aboveground harvest would reduce the decomposer populations and remove the supporting substrate, resulting in possible ion deficiencies during the next rotation (excluding weathering additions). Whole-tree harvest would leave marginal amounts of Mn available or recyclable in the ecosystem on these young soils to support the next rotation. Two guidelines for harvest and nutrient cycling in the Rocky Mountains were developed: (i) The growth of a forest within a rotation should not be subsidized by ions released through weathering during that rotation because the soil will not mature in fertility. (ii) There should be enough biologically essential ions on site at the time of harvest to grow the next three to four forest rotations to maintain a healthy ecosystem.
Adventitious rooting of eight conifers into a volcanic tephra deposit
Authors: Zobel Donald B. , Antos Joseph A.
Published: January 2008

During the second growing season after the 1980 eruption of Mount St. Helens, AbiesamabilisDougl. ex Forbes, A. procera Rehd., and Pinusmonticola Dougl. ex D. Don produced adventitious roots into tephra, the first known instance of rooting by these species. Abieslasiocarpa (Hook.) Nutt., Chamaecyparisnootkatensis (D. Don) Spach, Thujaplicata Donn. ex D. Don, Tsugaheterophylla (Raf.) Sarg., and T. mertensiana (Bong.) Carr. also adventitiously rooted; Pseudotsugamenziesii (Mirb.) Franco did not.
Survival and growth of outplanted Douglas-fir seedlings inoculated with mycorrhizal fungi
Authors: Bledsoe Caroline S. , Tennyson K. , Lopushinsky W.
Published: January 2008

Mycorrhizal and nonmycorrhizal container-grown Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were outplanted on dry, burned-over sites in eastern Washington. Prior inoculation of seedlings did not significantly increase survival or height growth, but biomass increment during the first growing season was substantially reduced. New roots of all seedlings became colonized by native mycorrhizal fungi within 5 months after planting.
A new analytical model based on the −3/2 power rule of self-thinning
Authors: Smith N. J. , Hann D. W.
Published: January 2008

A nonlinear analytical model is developed to describe the relationship between average plant size (weight or volume) and stand density in single-aged, monospecific plant populations. The model gives estimates of the slope and intercept of the −3/2 power rule asymptote, the nature of the size–density trajectory, and such features as relative density at crown closure and the effects of soil type or site index. The model is tested by growing red alder (Alnusrubra Bong.) seedlings under greenhouse and lath house conditions at three initial spacings (8 × 8, 4 × 4, and 2 × 2 cm) and two soil types (river loam and alder forest soil) for 525 growth days. There are seven harvests, starting at crown closure. All size–density trajectories tend consistently towards the same single asymptote irrespective of initial spacing, soil type, or age. The asymptote slope and intercept are 1.46 and ca. 94 kg tree−1•m−2. The crown closure line is parallel to the asymptote at a relative density of 4.6 × 10−3. The model also adequately describes the size–density trajectories for 20–50-year-old red pines (Pinusresinosa Ait.) growing at six initial spacings. The asymptote slope and intercept are 1.6 and ca. 87 × 103 m3•tree−1•ha−1, respectively.
Heritability, gain, and C effects in rooting of western hemlock cuttings
Authors: Foster G. Sam , Campbell Robert K. , Adams W. Thomas
Published: January 2008

Analysis of clonal variation for five rooting traits of western hemlock (Tsugaheterophylla (Raf.) Sarg.) clones demonstrated that clonal variation was due to both genetic and C effects (i.e., physiological or morphological characteristics unique to the ortet because of its specific environment). The potential bias to genotypic values of clones owing to C effects was significant, but heritability and gain estimates were only slightly biased. The five rooting traits were highly heritable (H2 = 0.87–0.92), and predicted genetic gain from clonal selection was substantial. Genetic correlations between pairs of traits were generally high (0.66−0.99); therefore, when selecting for any one trait, correlated responses can be expected in other traits.
Genetic structure and mating system of white spruce (Piceaglauca) in a seed production area
Authors: King John N. , Dancik Bruce P. , Dhir Narinder K.
Published: January 2008

Embryos and megagametophytes of open-pollinated seed of 37 white spruce (Piceaglauca (Moench) Voss) trees from a seed production area were analyzed by starch gel electrophoresis to determine the genetic structure and mating system over 2 seed crop years. Analysis of four polymorphic enzyme loci (Gdh, Idh, Pgm, and Pgi-2) for spatial and temporal genetic structure and mating system indicated substantial deviations from the random mating model that is assumed when open-pollinated families are designated as half-sibs.