bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of temperature control of production and nutrient cycling in two interior Alaska black spruce ecosystems
Authors: Cleve Keith Van , Barney Richard , Schlentner Robert
Published: July 2007

Selected indices of structure and function were used to evaluate the effect of differing soil thermal regimes on soil-permafrost-dominated (muskeg) and permafrost-free (north-slope) black spruce ecosystems in interior Alaska. The poorly drained, permafrost site displayed cooler soil temperatures and higher soil moisture content than were encountered on the well-drained north slope. Mineral soil nutrient pools generally were largest on the permafrost site. However, low soil temperature acted as a negative feedback control, suppressing soil biological activity, nutrient mineralization, and tree primary production to lower levels on the soil-permafrost-dominated site as compared with the permafrost-free site. Forty percent larger accumulation of tree biomass and 80% greater annual tree productivity occurred on the warmer site.
Container- and nursery-grown black oak seedlings inoculated with Pisolithustinctorius: growth and ectomycorrhizal development following outplanting on an Ozark clear-cut
Authors: Dixon R. K. , Garrett H. E. , Cox G. S. , Johnson P. S. , Sander I. L.
Published: July 2007

Containerized and bare-rooted black oak (Quercusvelutina Lam.) seedlings were inoculated with vegetative mycelial inoculum of Pisolithustinctorius and were grown in a greenhouse and a southern Missouri nursery, respectively. Following outplanting on a typical Missouri Ozark reforestation site, field data revealed that Pisolithus ectomycorrhizae increased survival and growth of the container-grown seedlings. Container-grown seedlings inoculated with Pisolithus exhibited significantly greater shoot and root growth than noninoculated control seedlings or inoculated bare-rooted seedlings. A complimentary relationship between root initiation, leaf area development, and shoot growth suggests a better growth potential of Pisolithus-inoculated container-grown seedlings than of noninoculated container-grown or inoculated or noninoculated bare-rooted seedlings. One year after outplanting, data revealed that Pisolithus is declining on the inoculated containerized and bare-rooted seedlings, but greater amounts of Pisolithus ectomycorrhizae are persisting on the container-grown plants.
Forest fire cycles and life tables: a case study from interior Alaska
Authors: Yarie John
Published: July 2007

The negative exponential and Wiebull distributions were used to estimate stand survivorship curves for forested sites in the Porcupine River drainage of interior Alaska. The survivorship curve of Piceaglauca (Moench) Voss sites was best described by a Wiebull function, while both functions adequately described the Piceamariana (Mill.) Britton, Sterns & Poggenburg hardwood and all sites stand survivorship curve. Fire cycles calculated from the Wiebull distribution were 43, 113, 36, and 26 years for the entire study area, P. glauca, P. mariana, and hardwood sites, respectively. Fire frequencies estimated from a life table analysis were 48, 105, 43, and 30 years, respectively. The relationship between fire cycle and fire frequency calculations is discussed and various management implications are given.
Some effects of different forest litters on seed germination and growth
Authors: Ahlgren Clifford E. , Ahlgren Isabel F.
Published: July 2007

Germination and growth of 12 native herbs, shrubs, and trees were followed in five litter components characteristic of successional stages of the northeastern Minnesota forest. Various litter components stimulated or inhibited seed germination and seedling growth of some species. Germination and growth were not always similarly affected, suggesting that different factors may be involved. Inhibition and lack of inhibition of some species on certain litter components correlate with natural habitat preferences of these species and the nature of the litter in these habitats. This information can be of use in improving results of seeding for site reclamation and reforestation.
Effects of storage, temperature, and moisture stress on seed germination and early seedling development of trembling aspen
Authors: Fechner Gilbert H. , Burr Karen E. , Myers Joseph F.
Published: July 2007

Fresh seed from seven clones of Populustremuloides Michx., and seed from the same collections stored at −18 °C for 1, 6, 12, and 24 months, were germinated at five water potentials (0, −2, −4, −8, and −12 bars; 1 bar = 100 kPa) and two night–day temperature regimes (20–30 °C and 15–25 °C).Germination was not significantly reduced at any moisture stress used, by storage. Average germination of fresh seed at 0 and −2 bars was 94%. Germination at −4 bars was 61% with much variation among clones and between temperature regimes. When the effect of temperature was significant, the 20–30 °C regime was the better. At −8 and −12 bars, little or no germination occurred.Coronet development occurred on at least 85% of the seedlings from all clones, after all storage times, under either germination temperature regime, at moisture stresses up to and including −8 bars. At −12 bars, coronet development occurred much less frequently, and the 20–30 °C temperature regime was the better. Cotyledon expansion occurred on at least 80% of the seedlings at moisture stresses up to and including −4 bars. At −8 and −12 bars, the frequency of cotyledon expansion dropped, and the 20–30 °C temperature regime was the better.
Estimation of plant biomass based on the allometric equation
Authors: Yandle David O. , Wiant Jr. Harry V.
Published: July 2007

Estimation of the parameters in the allometric equation by fitting a simple linear regression to the logarithmically transformed variables results in biased estimates of the arithmetic mean. This bias expressed as a percent of the mean approaches the limit −(1 − e−σ2/2) (100) as n increases. An adjusted estimator developed by Finney rather than the one given by Baskerville should be used when s2 is large and n is small. A change of measurement scale of the x or y variables presents no difficulty, but problems arise if variables are transformed to logarithms other than base e.
Sun and shade leaves: clues to how salal (Gaultheriashallon) responds to overstory stand density
Authors: Smith N. J.
Published: July 2007

Salal (Gaultheriashallon Pursh) leaf biomass, leaf area index, specific leaf area, and leaf morphology were examined in 13 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands from 37 destructively measured 1-m2 quadrats. In response to light and stand overstory density, salal shoots produced either mainly sun leaves or mainly shade leaves. Sun leaves were associated with sunflecks in open-grown or variably stocked stands. Shade leaves were associated with diffuse light under denser stands. Sun-leaf quadrats had mean specific leaf areas less than 90 cm2/g; shade-leaf quadrats had mean specific leaf areas greater than 90 cm2/g. Sun leaves were narrower, with average leaf widths less than 5 cm. Quadrat salal leaf biomass and leaf area index peaked at Curtis' metric relative density 5.9, which corresponded to an availability of 15% of global photosynthetically active radiation. Sun-leaf quadrats occurred below relative density 5; shade-leaf quadrats occurred above relative density 4. A mixture of sun- and shade-leaf quadrats occurred between about relative density 4 and 5, depending on the uniformity of stocking.
The mating system in natural populations of Thujaorientalis
Authors: Xie Chang Yi , Dancik Bruce P. , Yeh Francis C.
Published: July 2007

EM (expectation–maximization) algorithm procedures were used to estimate mating-system parameters in four natural populations of Thujaorientalis L. from China using seven allozyme marker loci (Fest1, Idh1, Idh2, Mr, Pgi2, Skdh1, and 6Pg2). The mean single-locus outcrossing rate was 0.70 for the species, but estimates showed that there was significant heterogeneity among loci within populations. Multilocus estimates of the outcrossing rate showed that there was significant heterogeneity among populations and among trees within populations. The mean multilocus outcrossing rate (0.75) was higher than the outcrossing rate (0.63) observed in a closely related conifer, Thujaoccidentalis L., but lower than estimates that have been reported for most other conifers. Significant heterozygote deficiencies, relative to Hardy–Weinberg and mating-system equilibria, were observed in all filial populations. In contrast, the maternal populations conformed to Hardy–Weinberg and mating-system equilibria at most loci. Self-fertilization and other forms of inbreeding (e.g., sibling mating) within the sampled populations are important contributors to the low outcrossing estimates in this conifer.
Estimating the distribution of a variable measured with error: stand densities in a forest inventory
Authors: Lappi Juha
Published: July 2007

If a variable is measured (or estimated) with error, then the distribution of the measurements is flatter than the true distribution. The variance of a measured variable is the sum of the true variance and the measurement error variance. If we shrink measured values towards their mean so that the variance will be equal to the true population variance, or its estimate, the obtained empirical distribution is more similar to the true distribution than is the distribution of measured values. To estimate the population variance, an estimate of the variance of measurement errors is required. If stand densities are measured by counting trees on fixed area or angle gauge plots, then a first approximation for the measurement (sampling) error variance can be computed assuming random (Poisson) spatial pattern of trees. The suggested estimation method is illustrated using an assumed distribution of stand densities.
Potential use of bialaphos, a microbially produced phytotoxin, to control red raspberry in forest plantations and its effect on black spruce
Authors: Jobidon Robert
Published: July 2007

Bialaphos foliar sprays were tested in eastern Quebec for control of red raspberry (Rubusidaeus L.), and the tolerance of planted black spruce (Piceamariana (Mill.) B.S.P.) seedlings was determined. Approximately 3 weeks after bialaphos was applied in July, August, or September, virtually all raspberry plants were killed. Efficiency of the June application, however, was much reduced. Spruce current-year foliage was more affected than older foliage. Foliar injury was more pronounced for bialaphos applications in June and July than for applications in August. First-year spruce survival was not affected by the treatments. Second-year evaluations revealed a significant quadratic relation of (i) month of application × bialaphos rate on raspberry density and (ii) bialaphos rate on raspberry height growth. Reduction in raspberry density and height growth was greater with the 2.0 and 2.5 kg active ingredient per hectare rates applied in August. As part of the evaluation of treatment efficiency, photosynthetically active radiation reaching spruce seedlings was measured using a portable integrating radiometer. Raspberry density and height growth were both negatively correlated with photosynthetically active radiation reaching spruce seedlings. A significant quadratic relation was found between bialaphos rate and 2nd-year spruce survival, which reached 95%, regardless of month and rate of application. A significant quadratic relation was found between spruce diameter growth increment and bialaphos rate. Except for calcium, 2nd-year spruce foliar mineral content was not affected by the treatments. Bialaphos treatments in August, with rates ranging from 1.0 to 2.0 kg active ingredient per hectare, had only slight or no adverse effects on spruce survival, foliar injury, and growth increment. Selective control of red raspberry in young black spruce plantations is a function of bialaphos rate and month of application.
Dating uprooted trees: comparison and application of eight methods in a boreal forest
Authors: Dynesius Mats , Jonsson Bengt Gunnar
Published: July 2007

Eight different methods for dating the fall of uprooted trees were used in a boreal spruce forest in northern Sweden: (i) cross dating, (ii) growth release, (iii) initial growth, (iv) tree regeneration on the fallen log, (v) tree regeneration in the pit, (vi) fell scar, (vii) reaction wood, and (viii) stage of decay. First, we calibrated the cross-dating method on tree falls of known age. Then, to evaluate the limitations of the remaining methods, all methods were used on 23 tree falls of unknown age where the results of cross dating were known to be reliable. Finally, 12 tree falls of unknown age, where cross dating was hard to conduct, were dated using all methods. Most methods gave only the minimum possible age. Cross dating and growth release were the only methods that gave exact-year results (i.e., the calendar year when the tree fall supposedly occurred). All methods contributed to the dating in at least some cases. Fewer methods gave valuable information in each old (> 50 years) uprooting than in each recent (< 50 years) one. For recent uprootings, cross dating always gave best obtainable results, but for older tree falls, no method was generally superior. The simultaneous use of several methods is recommended, especially for older tree falls.
Effect of heat sums and of heat applied separately to shoots and roots on flowering in potted Piceaglauca grafts
Authors: Ross Stephen D.
Published: July 2007

Two greenhouse experiments (1985, 1987) investigated the relationship between flowering and root activity in gibberellin A4/7 treated, potted Piceaglauca (Moench) Voss grafts subjected to heat (30 vs. 20 °C in 1985, 25 vs. 18 °C in 1987) applied separately to shoots and roots for 3 or 4 weeks during the period of cone-bud differentiation. Heat applied to roots significantly reduced the percentage of white-tipped roots during this period but had no effect on seed or pollen cones produced. Heat applied to shoots, which had no consistent effect on root activity, promoted flowering independent of root temperature. These results suggest that the flowering response to heat in P. glauca is mediated through the shoot, and not by retarding root activity as has been proposed. A third experiment (1988), in which entire grafts were exposed to heat treatments of 20, 25, or 30 °C for 5 or 10 h per day, disclosed a higher temperature requirement for maximizing pollen cones (10 h at 30 °C) than for maximizing seed cones (5 h at 20 °C). Male flowering was strongly correlated with the daily sum of degrees per hour above 10 °C.
Effect of cover crops on Cylindrocladium sp. in an Ontario bare-root nursery
Authors: Juzwik J. , Testa F.
Published: July 2007

Four species were grown as cover crops and incorporated into soil of field plots at Midhurst Nursery, Midhurst, Ontario, two times per growing season for 2 successive years. After two seasons, microsclerotial populations of Cylindrocladium sp. were higher in soils planted with alfalfa (Medicagosativa L., cv. Vernal) (p = 0.03) and Sudan grass (Sorghumbicolor (L.) Moench, cv. Green Leaf) (p = 0.10), and not different in soils with spring wheat (Triticumaestivum L., cv. Glen Lea), than populations in noncropped, fallow plots. Lower populations of the fungus were detected in soils planted with flax (Linumusitatissimum L.) (p < 0.08) than in the fallow ones. Highest disease incidence in black spruce (Piceamariana (Mill.) B.S.P.) transplants occurred when grown in plots treated with alfalfa, Sudan grass, and wheat. Disease incidence was lower in transplants grown in the flax plots than in those grown in the other plots (p < 0.001), including the fallow ones (p = 0.055). Spruce mortality was also less in the flax plots compared with all other treatment plots (p < 0.001).
Relationship of concentration of gaseous hydrogen fluoride to incidence and severity of foliar lesions in black spruce and white spruce
Authors: McCune D. C. , Lauver T. L. , Hansen K. S.
Published: July 2007

Quantitative estimates of the variation in response to air pollutants in natural populations of trees must be considered in predicting the magnitude of an effect or the risk of an effect's occurrence. This subject was investigated in 2-year-old black spruce (Piceamariana (Mill.) B.S.P.) exposed for 78 continuous hours to gaseous hydrogen fluoride at concentrations of 2.3, 4.2, or 8.1 μg% F•m−3 and with 3-year-old white spruce (Piceaglauca (Moench) Voss) exposed for 50 continuous hours to hydrogen fluoride at 2.6, 5.2, or 11.1 μg F•m−3 in open-top, field exposure chambers. Tolerances to hydrogen fluoride induced foliar injury followed a lognormal distribution for black spruce and white spruce with, respectively, estimated median tolerances of 3.45 and 13.24 μg F•m−3 and standard deviations corresponding to 1.70- and 2.14-fold changes in concentration of hydrogen fluoride. The curves for the occurrence of moderate and severe degrees of injury in black spruce paralleled that for the occurrence of any hydrogen fluoride induced injury but were displaced towards greater exposures (1.29-fold for moderate and 1.77-fold for severe injury). The distribution of foliar injury on shoots indicated that a portion of the variation in tolerance might be attributed to phenologic differences among the trees. A knowledge of the sources of variation and their magnitudes is necessary to recognize both incidence and severity of pollutant-induced injury in dose-response relationships.
Foliar injury symptoms and pigment concentrations in red spruce saplings in the southern Appalachians
Authors: Andersen Christian P. , McLaughlin Samuel B. , Roy W. Kelly
Published: July 2007

The frequency and percent surface area covered by necrotic flecking on red spruce (Picearubens Sarg.) needles from sapling-sized trees were examined on nine research sites on three mountains in the southern Appalachians. Foliar pigment analysis was conducted on trees from two of the nine research sites. Flecking increased with foliar age on all sites, and on two of the mountains the area covered by flecks increased with elevation. Above 1720 m on Clingman's Dome, foliar flecking was found to constitute >8% of the upper needle surface area of 1-year-old needles. Chlorophyll a and b concentrations increased with foliar age and were greater in trees growing at the mid-elevation site (1720 m) than at the high-elevation site (1935 m) on Clingman's Dome. Pigment concentrations did not correspond to foliar flecking frequency at these two sites. Foliar flecking appears to increase over winter, and its widespread occurrence throughout the southern Appalachians suggests that regional rather than local site-related phenomena are involved.
Using high-resolution airborne spectral data to estimate forest leaf area and stand structure
Authors: Smith N. J. , Borstad G. A. , Hill D. A. , Kerr R. C.
Published: July 2007

Techniques are developed to estimate stand leaf area index using high-resolution airborne spectral imagery. Leaf area index on 8 m radius plots was found to be strongly related to the normalized ratio of wavelengths in the red (674–687 nm) and near infrared (751–755 nm) part of the spectrum. Data from 17 stands were used. Leaf area index estimates included both the overstory (Douglas-fir, Pseudotsugamenziesii Mirb. (Franco)) and the understory (salal, Gaultheriashallon Pursh) over a range of stem densities.
Timing of gibberellin A4/7 application for cone production in potted black spruce grafts
Authors: Ho Rong H.
Published: July 2007

Potted 5-year-old grafts of black spruce (Piceamariana (Mill.) B.S.P.) growing in either a heated greenhouse or an outdoor holding area were sprayed weekly at 200 mg•L−1 gibberellin A4/7 for various durations and timings. The application began 1 to 6 weeks after vegetative bud break and continued until the end of lateral shoot elongation. Sprayings ended at the same time for all treatments, about 1 week before leaf primordial differentiation on the shoot apices. The best response in seed-cone production occurred when application began 2 weeks after bud break (midstage of rapid shoot elongation) and continued for 5 weeks; treatments were also effective when applications began 3 weeks after bud break or earlier and continued for 4 to 6 weeks. Treatments initiated later (4 to 6 weeks after bud break) were not effective. Grafts kept outdoors produced more seed cones than those kept indoors. The effects on cone production of gibberellin A4/7 application at four different concentrations were compared by spraying for 6 weeks, beginning 1 week after vegetative bud burst. Gibberellin A4/7 at 200 mg•L−1 was the lowest foliar spray concentration found to be effective in promoting seed-cone production.
Factors affecting pollen dynamics and its importance to pollen contamination: a review
Authors: Di-Giovanni F. , Kevan P. G.
Published: July 2007

Pollen contamination causes major losses to genetic improvement from selection and breeding of "plus" trees in conifer seed orchards. Genetic losses arise by the influx of "wild" conspecific pollen into seed orchards and its deleterious fertilization of superior genetic lines. This review firstly addresses the basis of the problem: pollen, conifer reproduction, and the concept of seed orchard management, especially in regard to reduction of contamination. Secondly, the physical processes of pollen liberation, dispersal, and deposition are described, and examples of previous studies illuminating these phenomena given. Thirdly, past research on measuring pollen dispersal in natural stands and seed orchards in discussed in the light of modelling techniques used to predict these types of dispersal pattern. Work on the other facets of contamination measurement, gene-flow studies, are listed. It is concluded that a detailed study that combines both the physical and gene-flow aspects of pollen dispersal should be initiated to compare and contrast the two methods, and that attempts to model pollen contamination should be sought.
Ambient cloud deposition reduces cold tolerance of red spruce seedlings
Authors: DeHayes D. H. , Thornton F. C. , Waite C. E. , Ingle M. A.
Published: July 2007

Laboratory cold-tolerance assessments were conducted between September 1989 and March 1990 on red spruce (Picearubens Sarg.) seedlings exposed to combinations of ozone (O3) and cloud water for two growing seasons on the summit of Whitetop Mountain, Virginia. Chamber treatments consisted of exposure to (i) ambient O3 and cloud water, (ii) ambient O3 and no cloud water, or (iii) reduced O3 and no cloud water. Ambient-air field plots were included to assess possible chamber effects. Red spruce seedlings exposed to ambient O3 and cloud water, either in chambers or field plots, were generally least cold tolerant, and differences were significant in October, November, December, and January. During 3 of those months, seedlings exposed to ambient O3 and cloud water in chambers were significantly less cold tolerant than either seedlings exposed to reduced O3 and no cloud water or seedlings exposed to ambient O3 only. There were no definitive effects of O3 in any month. The reduction in cold tolerance of seedlings exposed to O3 and cloud water appeared to result from the negative influences of acidic cloud deposition, rather than O3. This is the first conclusive evidence that ambient cloud deposition can impair the development of cold tolerance and maximum cold tolerance achieved in midwinter for red spruce growing in its native habitat. The 3 to 5 °C reduction in cold tolerance associated with exposure to ambient cloud water in this study may be sufficient to explain the winter injury observed frequently in northern montane red spruce stands over the past 4 decades.
LETTERS/FORUM
Authors: Romesburg H. Charles , Mohai Paul
Published: July 2007

not available
Estimation of seasonal ascospore production of Mycosphaerellapopulorum
Authors: Luley Christopher J. , McNabb Jr. Harold S.
Published: July 2007

A model was developed that estimates ascospore production by Mycosphaerellapopulorum Thompson in response to degree-days. Spore production and release in two field seasons were monitored with an ascospore liberation tunnel and Vaseline-coated slide traps, respectively. Ascospore production in a moist environment and under controlled temperatures was monitored in the laboratory with the liberation tunnel. Ascospores were produced in the laboratory for periods of 192, 98, and 74 days at 9, 16, and 21 °C, respectively, after initial ascospore maturation. Field and laboratory ascospore collection data were linearized with a Gompit transformation. Regression coefficients on the linearized data were greatest when a degree-day base of 0 °C was used. Slopes of the regression lines (k-values) developed from laboratory and field (1984 season) data were not significantly different. The k-values from laboratory data and data collected during the 1985 growing season were significantly different. The difference was attributed to dry weather during the period of ascospore production and release. The laboratory regression model could be used to predict ascospore production during the growing season after initial ascospore maturation if adequate moisture is present and if degree-day accumulation is predicted.
Aspects of productivity and nutrient cycling in an 8-year-old Eucalyptus plantation in a moist plain area adjacent to central Himalaya, India
Authors: Bargali Surendra S. , Singh Surendra P.
Published: July 2007

In the present study we describe biomass, productivity, and nutrient cycling in an 8-year-old Eucalyptustereticornis Sm. (Eucalyptus hybrid) plantation and compare them with those of a Populusdeltoides Bartr. plantation of the same age and area, a natural sal (Shorearobusta Gaertn. F.) forest, and other natural forests of the central Himalaya. The total vegetation biomass of the Eucalyptus plantation (126.7 t•ha−1) was lower than that of the P. deltoides plantation (176 t•ha−1) and natural forests (163.4–786.7 t•ha−1). The net primary productivity of the Eucalyptus plantation (23.4 t•ha−1•year−1) was similar to that of the P. deltoides plantation (25 t•ha−1•year−1) and the natural sal forest (22 t•ha−1•year−1). The net nutrient uptake of Eucalyptus was lower than that of Populus plantation and natural forests.
Stand density management strategies under risk: effects of stochastic prices
Authors: Teeter Lawrence D. , Caulfield Jon P.
Published: July 2007

A method is described for determining optimal economic strategies for density management in loblolly pine (Pinustaeda L.) stands in the southern United States. A stochastic dynamic programming model employs a price state transition matrix constructed using a first-order conditional cumulative density function for price based on time-series data for national forest pine stumpage in the South. The model also incorporates WTHIN, a pine growth and yield simulator widely used in the South to support analyses of alternative stand management strategies. Results indicate that at current average prices for pulpwood, on average sites, optimal planting density decisions recommended by the stochastic model are very similar to those obtained with a deterministic price equivalent. However, there are many instances where the thinning decisions recommended by the two models are different, especially when they are used to evaluate better sites or when the price of pulpwood is substantially increased above current region-wide averages.
Bark temperature patterns in ponderosa pine stands and their possible effects on mountain pine beetle behavior
Authors: Schmid J. M. , Mata S. A. , Schmidt R. A.
Published: July 2007

Bark temperatures on the north and south sides of five ponderosa pines (Pinusponderosa Laws.) in each of four growing stock levels in two areas in the Black Hills of South Dakota were monitored periodically from May through August 1989. Temperatures were significantly different among growing stock levels and between sides of the tree. The magnitude of differences between the mean bark temperatures in partially cut stands and uncut controls was inversely related to stocking level. Maximum differences in mean bark temperatures among the growing stock levels occurred between 10:00 and 14:00, when differences between the lower growing stock levels and the controls reached 9 to 10°F (Fahrenheit temp. = 1.8(Celsius temp.) + 32). Diurnal differences were greatly influenced by the amount of cloud cover. Nocturnal temperatures generally differed by 1 to 2°F. North-side temperatures were cooler and less variable than south-side temperatures. Temperature relationships and mountain pine beetle (Dendroctonusponderosae Hopk.) behavior are discussed.
Insitu needle and fine root respiration in mature slash pine (Pinuselliottii) trees
Authors: Cropper Jr. Wendell P. , Gholz Henry L.
Published: July 2007

Respiration of needles and surface fine roots was measured in a north central Florida slash pine (Pinuselliottii Engelm. var. elliottii) plantation. A controlled temperature chamber system was used to estimate respiration rates and Q10 values of insitu tissues over a range of 10 to 35 °C. Respiration rates did not differ significantly among seasons, fertilized versus unfertilized plots, or time of day in a diurnal time series (needles). Needle respiration from the lower canopy was less than that from the upper canopy. Fine root respiration measurements were consistent with previously made estimates based on soil CO2 partitioning and trenched plots.
The influence of opening size on snow evaporation in the forests of the Alberta Foothills
Authors: Bernier Pierre Y. , Swanson R.H.
Published: July 2007

Insitu snow evaporation was measured in circular openings, from 0H (full forest) to 5H (where H is the height of the surrounding trees; approximately 20 m), cut in the lodgepole pine (Pinuscontorta Dougl.) forest of the Alberta Foothills. Additional measurements were also made in a large 40H irregular clearing. The ratios of snow evaporation measured in the circular clearings to that measured in the large irregular opening were 0.24, 0.23, 0.28, and 0.41 for the 0H, 1H, 3H, and 5H, respectively. The aerodynamic approach yielded a good estimate of average daily snow evaporation in the large opening, with a computed value of 1.01 mm versus a measured one of 1.07 mm. Snow evaporation in the 0H opening was enhanced over that attributable to turbulent transport by nighttime radiative transfer from the canopy, which kept the snow warmer than in the other openings and prevented condensation. Vertical transfer efficiencies, the slope of the curve relating snow evaporation to the product of horizontal wind speed and vertical humidity gradient, were similar in all clearing sizes in spite of possible fundamental differences in wind fields created by the various canopy–opening interactions. Comparison of data from smaller openings with data from a previous study by A.J. West suggests that differences in snow evaporation between openings can be indexed to opening size.
Compensatory shoot growth in young black birch and red maple trees
Authors: Wilson Brayton F.
Published: July 2007

Black birch (Betulalenta L.) and red maple (Acerrubrum L.) trees 1.5–2 m tall responded by compensatory (increased) shoot growth following a single treatment where shoots on the whole tree were clipped. Total shoot length of clipped trees recovered to control levels after 1 year's growth. The remaining buds on clipped shoots grew more than they would have without clipping. Frequency distributions of shoot lengths shifted toward longer lengths in clipped trees in the 1st year, but were similar to controls 2 years after clipping. The longest shoots were as long, or longer, on clipped shoots as on unclipped shoots. The major compensatory growth mechanism was increased growth of lateral buds. Clipping induced a few preventi-tious buds to form shoots and a few unclipped short shoots to grow as long shoots.
A dynamic model of tree terminal growth
Authors: Gavrikov Vladimir L. , Karlin Iliya V.
Published: July 2007

A sequence "bud–shoot–bud …" was considered to model dynamics of height growth of a pine-like tree stem. Combination of "bud–shoot" and "shoot–bud" functions allows one to calculate a series of successive terminal shoot lengths, the sum of which corresponds to tree height at a given moment. A linear approximation of the model provides a flexible algorithm to simulate a wide range of S-shaped curves. To illustrate the model developed, an experimental study on Pinussylvestris L. bud growth was carried out. Buds were subjected to "free" growth (by removing neighboring buds) and to hunger growth (by defoliation of internodes). It was shown that length of P. sylvestris shoots was linearly and strongly related to length of the parent buds under both growth conditions.
Recent growth increases in old-growth longleaf pine
Authors: West D.C. , Doyle T.W. , Tharp M.L. , Beauchamp J.J. , Platt W.J. , Downing D.J.
Published: July 2007

Longleaf pine (Pinuspalustris Mill.) tree-ring data were obtained from an old-growth stand located in Thomas County, Georgia. The tree-ring chronology from the pine stand is composed of a collection of cores extracted from 26 trees ranging in age from approximately 100 to 400 years. These cores were prepared, dated, and measured, and the resulting data were examined with dendrochronological and statistical techniques. Beginning in approximately 1950 and continuing to the present, annual increments of all age classes examined in this study have increased, resulting in an average annual ring increment approximately 40% greater in 1987 than in 1950. When compared with expected annual increment, the increase for 100- to 150-year-old trees is approximately 45%, while the increase for 200- to 400-year-old trees is approximately 35%. In terms of stand-level aboveground biomass accumulation, the increased growth has resulted in approximately 5% more biomass than expected. The increased growth cannot be explained by disturbance; stand history; or trends in precipitation, temperature, or Palmer drought severity index over the last 57 years. Increased atmospheric CO2 is a possible explanation for initiation of the observed trend, while SOx and NOx may be augmenting continuation of this phenomenon.
Patterns of nitrogen mineralization and nitrification in floodplain successional soils along the Tanana River, interior Alaska
Authors: Klingensmith K.M. , Cleve K. Van
Published: July 2007

Cold climatic conditions govern the productivity of taiga forests, yet within a successional sequence the microclimatic and biogeochemical variations also have a major effect on soil microbial activities, thus affecting plant productivity through nutrient availability. Nitrogen mineralization and nitrification were measured in primary-successional floodplain forests of interior Alaska. Forest floor and mineral soils from an early (open willow), middle (poplar–alder), and late (white spruce) successional stage were used. The effects of temperature, moisture, and NH4+ were tested in the laboratory for each of the successional stages. Potential nitrification was estimated using the chlorate-inhibition technique. Surface mineral soils and white spruce forest floor had low to undetectable rates of nitrogen mineralization and nitrification (<1–3 μg N•g−1•d−1). The poplar–alder forest floor had the most pronounced seasonal patterns and the highest rates of net NH4+ mineralization (<1–7 μg N•g−1•d−1) and net nitrification (<1–21 μg N•g−1•d−1). Temperature was limiting in early and midsuccessional stages, and both moisture and temperature were limiting in the later white spruce stage. Ammonium additions increased nitrification only in the poplar–alder forest floor, suggesting the NH4+ is not limiting in the other successional stages. The chlorate inhibition assay indicated that a considerable portion of the nitrification in the poplar–alder forest floor may be due to heterotrophic activity.
A simplified tree bait for the mountain pine beetle
Authors: Borden J.H. , Chong L.J. , Lindgren B.S. , Begin E.J. , Ebata T.M. , Maclauchlan L.E. , Hodgkinson R.S.
Published: July 2007

Seven, split-block experiments throughout British Columbia in 1989 tested the efficacy of binary tree baits containing the pheromones trans-verbenol and exo-brevicomin or ternary baits with the addition of the host tree kairomone myrcene for containing and concentrating infestations of the mountain pine beetle, Dendroctonusponderosae Hopkins, in stands of lodgepole pine, Pinuscontorta var. latifolia Engelm. Attack densities on baited trees, attack frequencies of baited trees and trees within 10 m of the baited trees, and the ratios of newly attacked, green, trees to previously attacked, red, trees were generally statistically equal between sub-blocks containing binary or ternary baits. Where statistically significant differences occurred for one or more of the above criteria in one experiment, they were generally offset by statistically significant differences in the opposite direction in another experiment. Two individual-tree experiments in 1990 that supported the equality of binary and ternary baits indicated that raising the release rate of trans-verbenol in binary baits tended to reduce their efficacy (possibly because of contamination with the antiaggregation pheromone verbenone) and showed that increasing the release rate of exo-brevicomin tended to counteract this effect. When attack frequencies were subdivided by diameter class of available trees attacked, all baits were effective in inducing attack on available trees <30.0 cm diameter at breast height (1.3 m), but attack on baited and control trees ≥30 cm diameter at breast height was equal. Provided that the trans-verbenol in binary baits does not contain or autoxidize to verbenone, myrcene can be deleted from operational tree baits.
Palatability of Anispray®-treated white spruce to snowshoe hares
Authors: Rangen Sheila A. , Hawley Alex W.L. , Hudson Robert J.
Published: July 2007

Anispray®, a foliar spray, is a relatively new chemical product used to deter herbivore browsing. White spruce (Piceaglauca (Moench) Voss) trees treated with concentrations of Anispray® ranging from 25 to 100% sustained as much browsing damage as untreated trees by snowshoe hares (Lepusamericanus Erxleben). Damage levels were similar for Anispray®-treated and untreated controls in both preference and acceptability experiments. More research is required to develop and implement silvicultural practices, such as the use of chemical repellents, to reduce damage to reforested trees by herbivores.
Forest wildfires as a recent source of CO2 at northern latitudes
Authors: Auclair Allan N.D. , Carter Thomas B.
Published: July 2007

Since 1977, the extent of forest wildfires in the boreal and western regions of North America increased 6- to 9-fold over long-term trends, and an estimated 132 × 106 ha of temperate and boreal forest burned across the northern hemisphere. Emissions during and after burning may have been a significant feedback to global warming. Simulated carbon budgets indicated a hemispheric release of 1.4 Pg C during burning and 4.1 Pg C gross from CO2 fluxes postfire. The total release (5.5 Pg C) was 43% of the biospheric CO2 release to the atmosphere, 1977–1990. Over the next century (1991–2090), continuing emissions from wood and soil decomposition will release an additional 6.9 Pg C gross. A large CO2 release was contrary to assumptions of little net carbon flux in the temperate and boreal forests. The pattern of attenuated CO2 release in northern forests also contrasted with sharp emission peaks in tropical deforestation. A simulation experiment indicated that the CO2 pulse from direct emissions per unit area was 10-fold larger in tropical deforestation than in northern forest wildfires on average; postfire release in the northern systems, however, was about 10 times longer in duration and only slightly less overall than in tropical deforestation fires.
Growth trends of blue oak (Quercusdouglasii) in California
Authors: Kertis Jane A. , Gross Rob , Peterson David L. , Arbaugh Michael J. , Standiford Richard B. , McCreary Douglas D.
Published: July 2007

Long-term growth trends of blue oak (Quercusdouglasii Hook. & Arn.) at five sites in California were quantified and interpreted with respect to annual precipitation. Mean annual basal area increment (BAI) at sites with deep soil profiles or high precipitation was twice as great as growth at other sites. In general, BAI increased sharply during approximately the first 40 years of tree growth, then increased gradually or leveled off for the next 100 years. Limited data from older trees suggest that BAI decreases gradually after this point. Growth trends are relatively homogeneous within each site, but vary among sites. Most sites have relatively high correlations with precipitation compared with coniferous species at higher elevations. Interannual variation in soil moisture availability is clearly an important factor affecting annual growth of blue oak in the Mediterranean climate of California. This is the first known dendroecological study of blue oak growth trends.
Establishment of salmonberry, salal, vine maple, and bigleaf maple seedlings in the coastal forests of Oregon
Authors: Tappeiner John C. , Zasada John C.
Published: July 2007

To identify seedling regeneration niches for four coastal Oregon shrub and hardwood species (salmonberry (Rubusspectabilis Pursh), salal (Gaultheriashallon Pursh), vine maple (Acercircinatum Pursh), and bigleaf maple (Acermacrophyllum Pursh)) we studied the seed predation, emergence, survival, and growth of these species on disturbed and undisturbed soil in thinned, unthinned, and clear-cut conifer stands on two sites in the Oregon Coast Ranges. For all species, seedling emergence and survival were greater in thinned stands than in clearcuts or unthinned stands. In addition, emergence of salmonberry and salal was greater on mineral soil than on soil in which the organic layers were intact. After four years, height of salmonberry was greatest in the clearcuts, where it averaged 23 cm. Bigleaf maple and vine maple, which were heavily browsed in the clearcuts, reached their greatest height in the thinned stands, averaging 16 and 15 cm, respectively. Salal seedlings survived only in thinned stands and grew slowly, reaching a height of only 4–5 cm in 4 years. Seedling emergence and predation both were related to seed size. On both disturbed and undisturbed soil, vine and bigleaf maple, the species with the largest seeds, had the highest rates of emergence but also the highest rates of seed predation among the four species.
Spatial and temporal relationships between growth traits and metabolic heat rates in coast redwood
Authors: Anekonda T.S. , Criddle R.S. , Libby W.J. , Hansen L.D.
Published: July 2007

The relation of metabolic heat rates to growth of coast redwood (Sequoiasempervirens (D. Don) Endl.) trees was studied as a function of time in the growing season and location within the plantation. Significant within-clone variations in growth and metabolic heat rates were found among ramets growing in different sections of the plantation. Specific metabolic heat rates of all clones began to increase in early May, peaked in mid-July, and returned to a low level by September. Metabolic heat rates of individual clones, averaged over a 5- to 6-week period, were strong predictors (R2 = 0.93) of clonal height growth during that period.
Induction, rooting, and growth capacity of adventitious shoots of Pinuscontorta
Authors: Flygh Gunnar , Grönroos Roland , Arnold Sara Von
Published: July 2007

Zygotic embryos of Pinuscontorta Dougl. ex Loud, developed adventitious buds after a pulse treatment with 250 μM benzyladenine for 2 h. The number of embryos forming adventitious buds, as well as the number of adventitious buds per embryo, depended on the length of time after pulse treatment before the embryos were transferred to fresh medium. Adventitious shoots pulse-treated with 1.23 mM indole-3-butyric acid for 6 h started to develop roots within 3 weeks and after 3 months 75% of the shoots had developed roots. Roots usually emerged from vascular tissue that was connected to the vascular cylinder in the stem. However, roots could also be initiated directly from the vascular cylinder in the stem. The average relative growth rate per day for plantlets was 5.9% compared with 9.3% for seedlings. However, there was a correlation between the initial weight of the plantlets and their relative growth rate per day. Thus, plantlets classed in the group with highest initial fresh weight had a relative growth rate of 7.3%. Differences in growth rate between plantlets and seedlings are discussed.
Effects of soil organic layer removal on regeneration after clear-cutting a northern hardwood stand in New Brunswick
Authors: Roberts Mark R. , Dong Hongyun
Published: July 2007

Our objective was to determine the effects of clear-cutting and removal of the soil organic layer and residual vegetation on regeneration of woody species from seed. Germination, survival, and height growth of woody seedlings were followed over a 4-year period after clear-cutting in plots with and without the organic layer and vegetation removed. After 4 years, Betulaalleghaniensis Britton and Rubusidaeus L. predominated on the disturbed plots. On the undisturbed plots, Rubus, Acersaccharum Marsh. (mostly advance regeneration), and Acerpensylvanicum L. (new germinants and advance regeneration) were most abundant. Germination (all species combined) was 1.2–1.5 times higher on the disturbed plots in the first 2 years. Seedling survival was 19–33% higher on the disturbed plots in years 1 and 2 because of the lower occurrence of lethal surface temperatures (>42 °C). Little recruitment of most species occurred after year 2 except for A. saccharum, which increased in density over time on both treatments. Acerpensylvanicum occurred only on the undisturbed plots and decreased steadily in density over time. Differences among species in regeneration patterns were related to seed availability, seedbed characteristics, and regeneration strategies. Betula was the tallest species on 40% of the disturbed plots in spite of higher Rubus densities. Advance regeneration dominated 57% of the undisturbed plots. The relative heights, densities, and growth rates of species indicate that Rubus provides less competition than advance regeneration for Betula crop trees.
Large-scale 35-mm aerial photographs for assessment of vegetation-management research plots in eastern Canada
Authors: Pitt D.G. , Glover G.R.
Published: July 2007

Two 35-mm cameras were mounted on a boom and suspended from a tethered helium-filled blimp to obtain nominally vertical aerial photographs (1:828 and 1:414 contact scale) of vegetation-management research plots. Photo and ground estimates of woody plant crown area (m2/ha) and rootstock density (number/ha) were compared for several experimental vegetation-control treatments. Horizontal point-sampling estimates of total crown area made directly on 1:93 scale prints (enlarged from 1:414) correlated strongly with equivalent estimates made on the ground (n = 62, r2 = 0.97). An estimated 20 ground-truth plots were required to adequately quantify photo bias and correct subsequent prediction of actual total crown area on the plots studied. Much of the observed photo bias could be attributed to the undersampling of small rootstocks. Exclusion of individual rootstocks less than 0.10 m2 in crown area (or, equivalently, <56 cm in height) resulted in a 1:1 relation between the two sampling methods for estimates of both total crown area (r2 = 0.98) and rootstock density (r2 = 0.97). If data for rootstocks in smaller size classes are not needed, uncorrected photo estimates may be appropriate for evaluation of treatment response. Ground-sampling costs averaged $200 (Canadian) per plot, compared with photo costs of $104 per plot (without ground truth) or $150 per plot (with 20 ground-truth plots). Smaller scale photos (1:828 contact) cost 11% less than the larger scale tested, but resulted in significant undersampling of individual rootstocks less than 0.2 m2 in crown area (or, equivalently, <80 cm in height).