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Boreal mixed forests of trembling aspen (Populus tremuloides) and white spruce (Picea glauca) can provide higher outputs of many ecosystem goods and services, combined with resilience for changing environmental conditions. In this study, we examine the growth of white spruce and aspen over a range of stand compositions created by spot and broadcast treatments of broadleaves using manual and chemical means, aspen spacing, and untreated control. Twenty-two growing seasons postharvest, treatment responses created a range of broadleaf densities and spatial arrangements, reflected in significant differences in heights and diameters of the spruce mixedwood component. At this early seral stage, treatments have generated diversity in both tree species composition and stand structure. Modeling of the stand structures created by the different treatments provided outcomes ranging from pure conifer to broadleaf dominated when assessed by merchantable volumes. Broadleaf manipulations changed the relative proportion of spruce and broadleaf species in a mixture, achieving a variety of potential landscape and stand-level goals. Treatment differences were often not statistically significant until at least 16 years after stand initiation. Monitoring the achievement of mixedwood management goals will require longer time periods than currently employed for broadleaf or conifer monocultures. [ABSTRACT FROM AUTHOR]

To extend service life in exterior cladding applications, wood must be treated and/or coated. White spruce (Picea glauca (Moench) Voss) is a common wood species used in Canada for exterior cladding applications. White spruce is a refractory species and can be hard to treat with conventional approaches. Organosilanes could be an interesting wood treatment as condensation between organosilanes and wood hydroxyls can occur leading to a decrease in hydroxyl content, which are responsible for the dimensional instability of the wood. White spruce was pressure-treated with different formulations of organosilanes using acid and basic catalysts as well as hydrolysed and non-hydrolysed organosilanes. Weight percent gains were quite low (up to 11%) due to white spruce anatomy, and also because the organosilanes were located only in the cell wall. White spruce treated with organosilanes showed the best anti-swelling efficacy (up to 30%) for a non-hydrolysed formulation using an acid catalyst and the smallest organosilane molecule. The basic catalyst did not improve the anti-swelling efficacy compared to the acid catalyst because of its low mass gain. Three types of commercial coatings were applied on the treated wood and untreated control. The coated samples were submitted to accelerated UV exposure for 1,500 h to evaluate colour change and adhesion. The opaque stain exhibited the smallest total colour change (ΔEab*) with or without the modification of organosilanes. [ABSTRACT FROM AUTHOR]

Static bending tests to measure modulus of elasticity (MOEST) or wood stiffness provide an indicator of the structural performance of a finished product. These tests are however, slow and expensive. Tests to measure MOE using non-destructive testing (NDT) provide alternatives to MOEST tests; however, relationships between the different modes of measurement need to be established. Non-destructive testing MOE measured by two methods (SilviScan [MOESS] and time of flight [MOETOF]) have been compared with MOEST for lodgepole pine and white spruce. The relationships between stress wave speed (SWS) and MOEST have also been evaluated. Simple linear regressions of MOESS, MOETOF, and SWS had greater explanatory power (higher coefficients of determination (R2)) than did multiple linear regressions including growth rate or other wood fibre attributes. Simple linear regression from MOETOF and MOESS on MOEST had lower R2 for lodgepole pine than for white spruce; however, the converse was true for SWS. SWS had the highest R2 (89%) and MOESS the lowest R2 (47%) when regressed on MOEST in lodgepole pine. The results were tool and species specific, suggesting that R2 between MOEST and non-destructive testing MOE values must be validated separately for each commercial tree species and for each measurement technique. [ABSTRACT FROM AUTHOR]

Diameter at Breast Height (DBH) plays an important role in forest management. New technologies such as airborne and terrestrial Light Detection and Ranging (LiDAR) are expensive and time-consuming. We explored the iPad LiDAR sensor to measure DBH considering affordability and availability. The study was carried out at a research forest plantation near Thunder Bay, Ontario, Canada. Five plots were selected for differences in stem spacing, average DBH and species, and made 360° scans separately. A manual circle fitting method was used to produce circular features for the estimation of DBH. The coefficient of determination (R2) between estimated DBH and field measurements was 0.52, indicating a moderate accuracy. The Root Mean Square Error (RMSE) of DBH estimation ranged from 2.82 cm to 8.24 cm. The accuracy of smaller red pine trees was found to be relatively higher than that of larger red pine and white spruce trees. These accuracies did not change with the distance from the scanning location to trees. Therefore, results showed the potential use of an iPad LiDAR Scanner for DBH estimation. We recommend developing an application combining the iPad's location and LiDAR sensors and incorporating a precise positioning method for fieldwork, and further broad field testing. [ABSTRACT FROM AUTHOR]

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Nickel (Ni) in trace amounts is important in plant nutrition; it can also be toxic in excess. The objective of this study was to determine if nickel affects gene expression in white spruce (Picea glauca). Nickel toxicity was assessed by treating seedlings with an aqueous solution of nickel nitrate salt [Ni(NO3)2] at different doses (150, 800 mg/kg, and 1600 mg/kg) using a completely randomised design. Expression of the genes encoding 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) and glutathione reductase (GR) in roots and needles were investigated using RT qPCR analysis. No damage was observed on P. glauca seedlings. This study revealed that Ni induces an upregulation of ACCD at low and high doses tested in roots. Nickel treatments resulted in a downregulation of GR at low dose (150 mg/kg) in needles and an upregulation at low and high doses in roots. This suggests that the low level of bioavailable nickel in mining sites in Ontario and other regions can trigger changes in gene expression. The results also show that potassium nitrate induces a significant effect on gene expression in P. glauca mostly at high concentrations. [ABSTRACT FROM AUTHOR]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Depletion of white spruce (Picea glauca) in mixedwood forest is a frequent problem, particularly in stands that were high-graded as a result of inadequate silviculture and spruce budworm (Choristoneura fumiferana) epidemics. To provide information that will help guide restoration efforts, we assessed the effect of four seed-tree retention (STR: 0, 10, 40 and 60 trees/ha) levels and two scarification (SC: patch scarification and disk-trenching) types on white spruce reintroduced by planting in a high-graded yellow birch (Betula alleghaniensis)–conifer stand. We present the 9-year results from the seedling physiology, nutrition and morphology. Physiology and nutrition changed with years, but did not vary with STR levels and SC types. Significant increases in the number of internodal branches, height growth, and total height at the two lowest STR levels and after release suggest that the performance of white spruce in terms of morphology and growth is sensitive to small variations in available light. Because seedling morphology and growth were similar between SC types, a moderate disturbance of the forest floor by disk-trenching would be sufficient at a relatively low cost. Our findings highlight that the STR levels influenced the morphology and growth of planted white spruce seedlings more than the SC types. [ABSTRACT FROM AUTHOR]

We employ a dendrochronological approach to examine spatial variation in radial tree growth-climate relationships and responses to global climate oscillations across the geographic ranges of Picea glauca and Picea engelmannii. Tree-ring chronologies were constructed for 77 sites and analyzed using correlation coefficients for monthly climatic variables. In general, for Picea glauca, stands in the western portion of its range had significant negative correlations with temperature during fall, winter, and spring; only summer temperature was positively correlated with tree growth. In eastern North America, Picea glauca growth was negatively correlated with winter and spring temperature. Across the north-south range of Picea engelmannii, growth of northern populations was positively correlated with temperature in most seasons except spring, which had negative correlations, and response to winter precipitation differed between northern and southern populations. However, some monthly values for both species correlations were altered due to decadal oscillation phase, especially for the Pacific Decadal Oscillation. [ABSTRACT FROM AUTHOR]

Decades of live-fire training exercises have left millions of acres of military training lands contaminated with various munitions constituents such as dinitrotoluene. Those that pose a threat to higher organisms due to their toxicity and mobility in the soil are of particular concern. Plants aid in the biodegradation and phytoextraction of contaminants, and site-specific ecotoxicity determinations are critical to inform effective remediation strategy. These ecotoxicity determinations are lacking in cold-adapted plants and would be very informative for contaminated training lands in cold regions. Therefore, we conducted a phytotoxicity study to determine the median effective concentration (EC50) of 2,4-dinitrotoluene (2,4-DNT) to four native Alaskan plant species in a sub-Arctic soil at two different temperatures. Plant species investigated were white spruce (Picea glauca), field locoweed (Oxytropis campestris), bluejoint grass (Calamagrostis canadensis), and Jacob's ladder (Polemonium pulcherrimum). Seedling emergence, fresh plant mass, and dry plant mass were used to model plant response to 2,4-DNT contamination. White spruce was most tolerant to 2,4-DNT contamination (EC50 = 130.8 mg kg−1) and field locoweed was least tolerant (EC50 = 0.38 mg kg−1). In general, Arctic plant species were more vulnerable to 2,4-DNT when compared to plant types native to temperate or tropical regions. [ABSTRACT FROM AUTHOR]

The processes for producing conifer planting stock by somatic embryogenesis (SE) in conifers are described. Implementation of SE presents opportunities and limitations at various stages of the in vitro process. The topic of genetic stability, or somaclonal variation, is a particular concern and reviewed. Following the in vitro processes, several factors affect the successful acclimation, early growth and field performance of SE planting stock. Experiences with other conifer species in the context of commercial production are reviewed. While SE production has historically been a very labor-intensive process, recent advances have been made to automate the various steps. Developments to enable SE for Norway spruce in Sweden are described. [ABSTRACT FROM AUTHOR]

Tree species identification is important in forest management. The multispectral lidar Titan of Teledyne Optech Inc. can improve tree species separation by providing classification features computed from the three-channel intensities, ratios and normalized differences. However, the value of features used in classification algorithms (e.g., random forest, RF) may vary with tree size. The focus of the present study is to show how tree height influences the 3D and intensity features, how this relationship may affect the species classification accuracy, and how different classification strategies may circumvent this problem. Six needleleaf species (Pinus resinosa, Pinus strobus, Pinus sylvestris, Larix laricina, Picea abies and Picea glauca), found in plantations of different ages, were sampled to train classifiers. Some features yielded a good discriminatory power for species identification, despite their relation to tree height (r2 up to 0.6). Two classification strategies—a) using only size-invariant features (SIF) and b) training separate classifiers per tree height strata (HSC)—were compared to a standard classification (STD: all features, without height stratification). The accuracy of the SIF approach was lowest, useful variables being removed due to their relationship to tree height. The HSC provided only a minor improvement over the STD results. [ABSTRACT FROM AUTHOR]

Although sustainable forest management is accepted worldwide in concept, challenges in the methods of implementation remain. Using local data sets from Alberta, Canada, we show that a simulation approach can assist the implementation of sustainable forest management by improved understanding of product potential and other forest ecosystem goods and services that forests can provide for a given forest inventory. This will assist facilitating trade-offs among them for an optimal wood utilization strategy to achieve sustainable forest management. In this example, effects of wood utilization standard on merchantable volume, lumber volume, and number of trees that can produce at least one piece of lumber are quantified, and a conversion method for wood volumes under different wood utilization standards is presented. Wood utilization standard is the combination of stump height and diameter inside bark at merchantable height, which considerably influences available volume quantity of forest resource. However, such influences have not been quantified for sustainable forest management implementation. Our results not only confirmed that merchantable and lumber volumes increased with decreasing stump height and diameter inside bark at merchantable height, but also revealed that this trend will not hold when diameter inside bark at merchantable height is less than 7 cm. [ABSTRACT FROM AUTHOR]

Contamination of soils with the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, Research Department Explosive) as a result of military applications is a large-area problem globally. Since coniferous trees dominate the vegetation of large areas of military land in Central Europe, particularly in Germany, the long-term fate of14C-RDX in the conifers Scots pine and Dwarf Alberta spruce was studied. Acetic acid was the most effective solvent for the removal of extractable RDX residues from homogenates of RDX-laden tree material (85%, 80–90% and 64–80% for roots, wood and needles, respectively). On average, only a fifth of RDX-derived14C was bound in non-extractable residues (NER). Within the main cell wall compartments, lignin was the dominant binding site for NER (needles: 32–62%; roots: 38–42%). Hemicellulose (needles: 11–18%; roots: 6–11%) and cellulose (needles: 12–24%; roots: 1–2%) were less involved in binding and a considerable proportion of NER (needles: 15–24%; roots: 59–51%) was indigestible. After three-year incubation in rot chambers, mineralisation of tree-associated14C-RDX to14CO2clearly dominated the mass balance in both tree species with 48–83%. 13–33% of14C-RDX-derived radioactivity remained in an unleachable form and the remobilisation by water leaching was negligible (< 2%). [ABSTRACT FROM PUBLISHER]

Tree improvement programs aim to develop families that are well-adapted to future growing conditions. To gain insight into the stability of the family genetic response to climate change, white spruce (Picea glauca) seedlings from 60 full-sib families were subjected to a combination of two temperature regimes and two levels of CO2over two growing seasons. There was positive effect of warmer temperatures and higher CO2on some growth variables but no significant family × treatment interactions. Instantaneous water use efficiency was the only physiological trait that was affected positively by the CO2treatment, showing a 51% increase that was consistent across families. [ABSTRACT FROM PUBLISHER]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Height and diameter of white spruce clones were measured over two growing seasons in a forest nursery and for 4 more yr at two field sites. Clonal heritability (Hc2) was moderate and stable in the nursery, but decreased with age, reaching 0.26 and 0.11 for height and 0.14 and 0.04 for diameter, respectively, at the two field sites. Height exhibited weak to moderate Hc2and strong genotypic correlations with the different growth characteristics. The strong age-age genotypic correlations (≥0.809) and nursery-plantation correlations (≥0.347) for height indicate that selection for height can be conducted at a young age thus reducing the costs of clonal tests. [ABSTRACT FROM PUBLISHER]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Density manipulation of overstory aspen provides increased light levels to promote growth of understory spruce, while it may also impact the air and soil temperature. We monitored temperature for three growing seasons in young mixedwood stands of variable density at two boreal locations in Alberta, Canada. Results indicate that partial aspen cover provides frost protection that may be location specific. Mean air temperature was similar or increased slightly across aspen densities during the growing season, while mean soil temperature significantly increased with decreasing overstory cover. The amount of accumulated air and soil heat over the growing season was inversely related to aspen density. The differential impact of density on temperature contributes to variation in growth relationships and may explain regional differences in competition effects. [ABSTRACT FROM AUTHOR]

Recent studies have revealed positive and negative trends in the radial growth of treeline white spruce (Picea glauca) as temperatures have warmed in recent decades. Investigators have speculated that negative growth trends reflect the increasing importance of temperature-induced drought stress, yet direct observations of drought-induced stomatal closure have not been made in white spruce near the Arctic treeline. In this study, we measured needle gas exchange, a variety of needle traits, and branch growth in contrasting growing seasons on a riverside terrace near the Arctic treeline in Noatak National Preserve, northwest Alaska. Needle gas exchange was limited by cold soils (<7 °C), nighttime frosts, large vapor pressure deficits (VPD) and/or low soil water contents during the majority of our midday measurements. Near optimal conditions for needle gas exchange were consistently found in late August, when soils were relatively warm, air temperatures were moderate, and the VPD was relatively small. Defoliation during a two-year bud moth infestation (Zeiraphera spp.) substantially reduced branch growth, obscured potential relationships between needle gas exchange and growth, and revealed the importance of whole canopy gas exchange measurements. Results of our study show there is a very narrow window of environmental conditions for near optimal needle gas exchange in white spruce near the Arctic treeline. Although we identified many abiotic constraints on needle gas exchange, a single biological factor likely had the greatest effect on annual branch growth. [ABSTRACT FROM AUTHOR]

Height and diameter distributions between improved and unimproved (checklot) seedlots for white spruce [Picea glauca (Moench) Voss] and black spruce [Picea mariana (Mill.) BSP] were compared using the two-parameter Weibull function. Individual tree height at age 5-15 years and diameter at breast height at age 15 years that were collected from two series of large-plot realized gain tests were used for this purpose. For both species, improved seedlots did not significantly (α=0.05) change the shape parameter of the distributions relative to their checklots, suggesting that an overall shape value will be adequate to predict tree size distributions of various improved seedlots. The most important finding was that seedlot influenced the scale parameter (related to the range of the distribution) significantly, but from a practical viewpoint, only those scale values of the higher rated seedlots (i.e. seedlots collected from a rogued seed orchard or superior families) were significantly higher (α=0.05) than those of the respective unimproved seedlot. The changes in scale value of the alternative improved seedlots relative to the checklot (ΔScale) were comparable in magnitude to the respective realized genetic gains, suggesting that tree improvement effects on the scale value can be adjusted by realized genetic gains. The results also suggest that site and age significantly affected the scale value; in general, ΔScale became larger at earlier ages or on better sites. The findings reported here will be used in the development of yield functions for genetically improved white and black spruce in New Brunswick. [ABSTRACT FROM AUTHOR]

Here we present the first tree-ring series (1850-2003) of stable carbon (δ13C) and oxygen (δ18O) isotope ratios from a high-latitude treeline site in northwestern Canada. Both δ13C and δ18O were measured at annual resolution from whole-ring α-cellulose of three white spruce trees (Picea glauca [Moench] Voss) growing in the Mackenzie Delta. There is a strong positive association between δ13C and maximum summer temperatures. This relation likely results from the influence of temperature-induced drought stress on stomatal conductance. Mean summer relative humidity is also significantly correlated, inversely, with δ13C reflecting its direct influence on stomatal conductance. The δ18O record is strongly and positively correlated with early-spring to mid-summer minimum temperatures likely owing to the temperature dependence of δ18O in precipitation and uptake of this water during the growing season. Mean summer relative humidity is also significantly and inversely correlated with δ18O due to leaf water evaporative enrichment. Our δ13C and δ18O records contain a large amount of climate-driven variability indicating their considerable potential to infer past climate changes in the Mackenzie Delta. [ABSTRACT FROM AUTHOR]

In Canada, the coniferous forest was generally found to be nitrogen (N) deficient, but base cation deficiencies may be becoming more prevalent. Newly-developed nutritional standards based on leaf nutrient concentrations and compositional nutrient diagnosis (CND) were applied on published data of white spruce nutrition from sites across Canada. Results suggest that nutritional disorders in white spruce are not restricted to N deficiencies. Based on nutrient concentrations, deficiencies are common, particularly in phosphorus (P), potassium (K), and calcium (Ca), but toxicities are rare. The CND analysis revealed some cases of excess N, P, and magnesium (Mg). [ABSTRACT FROM AUTHOR]

Hydrocarbon-contaminated wastes generated from oil and gas drilling activities may be used as a soil amendment once composted and further decomposition of residual hydrocarbons can be accomplished after the composts are applied to soils. To test if N fertilization may enhance hydrocarbon decomposition, we investigated the effects of N application on hydrocarbon degradation in different-aged composts (1-, 2-, 3-, and 4-year-old composts, coded as 1Y, 2Y, 3Y, and 4Y composts, respectively) through a pot experiment planted with white spruce (Picea glauca [Moench] Voss) seedlings. The percentage degradation of total petroleum hydrocarbon (TPH, C11 to C40) in the composts without N fertilization was correlated to initial NH4+ concentrations (R = 0.99, P<0.001). The percentage degradation of TPH was highest in the 3Y compost (41.1%) that had an initial level of 325.3 mg NH4+-N kg-1 and the lowest in the 1Y compost (9.3%) that had an initial level of 8.3 mg NH4+-N kg-1. The degradation of TPH was enhanced by N fertilization in the 1Y (from 9.3 to 15.3%) and 4Y composts (from 14.3 to 22.6%) that had low initial NH4+ concentrations. Our results show that application of NH4+-based fertilizers may enhance the degradation of TPH when initial NH4+ concentrations in the compost are low. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of spruce budworm (Choristoneura fumiferana) on balsam fir (Abies balsamea) and white spruce (Picea glauca) at Itasca State Park in northwestern Minnesota. We studied the species composition, age structure, and radial growth patterns in tree rings along five belt transects at sites infested with spruce budworm. Our objectives were to: (1) discover when the latest spruce budworm outbreak started; (2) determine whether tree growth was similarly reduced in earlier decades, suggesting earlier spruce budworm outbreaks; and (3) test whether radial tree growth and the start of the outbreak(s) were correlated with climate. We used the computer program OUTBREAK to determine that the current spruce budworm infestation began to reduce tree growth in the 1 990s, before it was detected by park officials in 2001. The tree-ring record indicated that growth of the host-species trees was periodically reduced at all sites prior to the 1990s. We found no consistent relationship between temperature/ precipitation and the initiation of spruce budworm outbreaks, as reconstructed by the OUTBREAK program, at the southwestern edge of the distribution of balsam fir. The Palmer Drought Severity Index, however, was positive (i.e., wetter-than-normal conditions) before increased spruce budworm activity at all sites. Outbreaks are related to climatic conditions, but they also depend on other factors such as the availability of sufficient food for the spruce budworm. [ABSTRACT FROM AUTHOR]

The 19-20-year effects of mechanical site preparation, windrow burning, chemical site preparation, and postplanting vegetation control on survival and growth of planted white spruce are reported from two boreal sites in British Columbia, Canada. Survival differed between treatments at both sites, but was relatively good (≥77%) even in untreated plots. Current data regarding the proportion of spruce that were physically overtopped by vegetation and previous results from related soils and vegetation studies suggest that lasting reductions in tall shrub and aspen abundance were more important to spruce growth than early microenvironmental effects associated with manipulating the rooting environment. At Inga Lake, postplanting vegetation control produced a 13-fold increase in spruce volume over the control after 19 years, which was statistically equivalent to increases resulting from fine mixing, plow-inverting and windrow burning site preparation treatments. At Iron Creek, chemical site preparation and plow-inverting quadrupled spruce volume, whereas mounding, patch scarification and disc trenching were ineffective. Growth and yield simulations using treatment-specific site index curves for Inga Lake suggested that rotation length could be shortened by 12-16 years through the use of site preparation or postplanting vegetation control. However, untreated areas, due to the relatively good survival of white spruce at age 19, were predicted to produce equivalent volume if left to grow to mean annual increment culmination age. [ABSTRACT FROM AUTHOR]

The objectives of this study were (1) to compare six methods for predicting parameters of the Weibull probability density function (PDF) for diameter at breast height (dbh) distribution in the unthinned white spruce plantations in eastern Canada with respect to their applicability, and (2) to evaluate their predictive abilities in terms of error index (EI) and Kolmogorov-Smirnov (K-S) statistic. The reasons for undertaking this study were (1) there are no available models for the dbh distributions of the studied species and (2) to determine the best method for projecting dbh distributions of white spruce plantations. A total of 113 sample plots which consisted of the commonly measured stand-level variables [stand age (A), site index at 25-year base age (SI), average height of dominant and co-dominant trees (Hd), and stand density (SD)] and associated diameter frequency distributions were used in this study. Of all the six prediction methods, the moment-based and percentile-based parameter recovery approach (PRM and PCT), maximum likelihood estimation regression (MLER), cumulative distribution function regression (CDFR) and parameter prediction method (PPM) were able to be applied for adequately modeling the diameter frequency distributions for the data sets used in this study. The moment-percentile estimation hybrid method (HYBM) performed the poorest. PCT was most highly recommended as it had the consistently lowest EI and K-S statistic values for both fit and validation data sets. Therefore, the dbh distributions for white spruce plantations could be predicted at a point over time using the established methods here, especially the PCT method, from the stand variables (A, SI, Hd, SD). [ABSTRACT FROM AUTHOR]

To better understand the effects of cloning on observations of fungal ITS sequences from Picea glauca (white spruce) roots two techniques were compared: (i) direct sequencing of fungal ITS regions from individual root tips without cloning and (ii) cloning and sequencing of fungal ITS regions from individual root tips. Effect of root tip size was investigated by selecting 20 small root tips (SRT, 1.0-2.0 mm long) and 20 large root tips (LRT, 5.0-6.0 mm long). DNA was isolated from each tip and PCR-amplified with fungal-specific primers. PCR reactions were divided into two portions, one of which was sequenced directly and one of which was cloned first followed by sequencing of 12 random clones. With direct sequencing all 20 SRT produced an identifiable sequence, while only 13 of 20 LRT (65%) yielded an identifiable sequence. With cloning and sequencing all 40 tips produced identifiable fungal ITS sequences regardless of size. Failure of direct sequencing in LRT was associated with the presence of multispecies assemblages. Cloning identified 18 taxa overall while direct sequencing identified four. Cloning was not affected by tip size and identified more taxa relative to direct sequencing, although cost and probability of observing lab-based contaminants (e.g. airborne or reagent-based) were higher. We suggest that standardized controls be run whenever clones are sequenced from environmental samples, including positive controls derived from pure cultures and negative controls that cover the entire extraction, amplification and cloning process. Additional studies on larger root segments and bulked samples are needed to determine whether cloning can detect fungi accurately and cost-effectively in complex environmental samples. [ABSTRACT FROM AUTHOR]

Many attempts have been made to reconstruct past soil chemistry from tree rings' total element concentrations. However, a few recent studies have shown that some elements are highly mobile within some tree species' sapwood, which may complicate the interpretation of temporal trends. To investigate element mobility in xylem of balsam fir (BF) and white spruce (WS), a dendrogeochemical method was utilized, which consists in sequentially extracting tree ring samples with water and diluted hydrochloric acid (HCl; 0.05 M) followed by a complete digestion in nitric acid (residual). The results show that, within the sapwood of BF and WS, potassium (K) and phosphorus (P) are found mostly in the water extract whereas divalent cations [calcium (Ca), magnesium (Mg), strontium (Sr), manganese (Mn), zinc (Zn), and barium (Ba)] are mainly present as soluble or exchangeable forms. Total xylem concentration generally decreased in the following order for both tree species: Ca > Mg > Mn > Zn, Ba > Sr. At the opposite, the vast majority of aluminum (Al) (>99%) and iron (Fe) (>95%) is found in the residual fraction, suggesting that these elements are not affected by radial reequilibration during circulation of the sap. Because Al soil availability is known to increase with decreasing pH, this element can potentially be used for past reconstruction of soil pH. [ABSTRACT FROM AUTHOR]

This study examined the impact of increased irrigation efficiency on the hardening and frost tolerance of 2-year-old containerized white spruce seedlings in the context of groundwater protection, irrigation management and the maintenance of seedling quality in northern climates. The seedlings were grown under three different irrigation regimes (IR =30%, 40% and 55% v/v; cm3 H2O/cm3 substrate) and were hardened under conditions of natural photoperiod and temperature. After being subjected to artificial frost tests on four sampling dates during autumn, the seedlings were compared for bud development and frost tolerance. IR had no influence on frost tolerance as determined by measurements of physiological (electrolyte leakage, root water loss) and morphological (shoot damage, root initiation) variables. At the end of the second growing season, there was no significant difference between IRs in seedling height, root collar diameter, shoot dry mass and root dry mass. The results indicate that the amount of water applied to large-dimension 2-year-old white spruce seedlings during the growing season can be significantly decreased without prematurely impeding their growth or hindering their acquisition of frost tolerance. [ABSTRACT FROM AUTHOR]

Thirty-five stands of mature, closed canopy black spruce (Picea mariana), white spruce (Picea glauca) and balsam fir (Abies balsamea) in Prince Albert National Park, Saskatchewan, were assessed for cumulative defoliation caused by eastern spruce budworm (Choristoneura fumiferana). Multitemporal Landsat 5 TM images (15 June 1992 and 18 July 2004) and a single-date SPOT 4 HRVIR (high resolution visible and infrared) image (19 August 2004) were obtained over these stands. Correlation analysis suggested that the strength of the relationship between the defoliation and various vegetation indices was generally moderate. The SPOT HRVIR indices were more highly correlated to cumulative defoliation than the Landsat indices, and the multitemporal Landsat TM index outperformed the single-date Landsat TM index. These results may help in the design of defoliation assessment procedures that integrate satellite remotely-sensed data and aerial sketch mapping techniques. [ABSTRACT FROM AUTHOR]

The incidence of type 2 diabetes mellitus has reached epidemic proportions worldwide. Canadian aboriginal communities, particularly the Cree Nation of Eeyou Istchee, have been identified as a high-risk population. Culturally acceptable treatment options are limited notably for diabetic complications resulting in peripheral neuropathy. Here, we describe results of an ongoing collaborative research project with Cree of Eeyou Istchee to identify botanicals capable of protecting peripheral neuronal precursors from glucose toxicity and glucose deprivation in vitro. Polar fractions of three plant organs (needles, cone, and bark) collected from Picea glauca (Moench) Voss (Pinaceae), were tested for toxicity under normoglucose, glucotoxicity, and glucose deprivation conditions. The profile of phenolic metabolites in each extract was first characterized by high-performance liquid chromatography-diode array detection-atmospheric pressure chemical ionisation mass spectrometry (HPLC-DAD-APCI/MS). We report here that these fractions are well-tolerated by PC12 neuronal precursors under normoglucose conditions. LD50 concentrations of needle extracts exceeded 100 μ g/mL, whereas the LD50 of bark and cone extracts was 40 and 36.4 μ g/mL, respectively. We further show that the cytoprotective properties of minhikw after glucose challenge are concentration-dependent and organ-specific. Needle extracts protected PC12 cells from both glucotoxicity and glucose deprivation. Bark extracts had negligible activity. Cone extracts further impaired PC12 cell glucose tolerance. This study provides the first validation of antidiabetic activity of minhikw organs at the cellular level relevant to the management of diabetic peripheral neuropathy. [ABSTRACT FROM AUTHOR]

Standards of optimum nutrition are not readily available for mature trees of the Canadian boreal forest. The objective of this study was to determine foliar nutritional standards for white spruce for all major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and manganese (Mn)] using critical values (CVA) and compositional nutrient diagnosis (CND). Trees were sampled at two locations in Ontario and Quebec to cover a gradient of soil fertility levels. A boundary-line approach was used in combination with quadratic regression models to estimate the relationship between growth and foliar-nutrient concentrations or CND scores when free of the effects of interacting environmental factors. White spruce optimum nutrition ranges were computed from significant relationships (P ≤ 0.10) for N, P, K, Ca, and Mn concentrations and for N, P, and K CND scores. Optimum concentrations for first-year needles were 12.3, 1.9, 7.3, 6.5, and 0.39 mg g -1 for N, P, K Ca, and Mn, respectively, whereas optimum CND scores were 0.17, -1.65, -0.40, and -0.30 for N, P, K, and Ca, respectively. Samples from a broader range of environmental conditions will be required in order to establish standards for all major nutrients and to ascertain toxicity levels of most nutrients. [ABSTRACT FROM AUTHOR]

Previous studies conducted in growth chambers had demonstrated the successful experimental inoculation of white spruce seedlings with anti-insectan toxin producing needle endophytes. Needles colonized with the rugulosin-producing endophyte 5WS22E1 (DAOM 229536) contained rugulosin in concentrations that impaired spruce budworm growth. Here we report experimental inoculations conducted under nursery conditions. To improve the reliability of detecting successful colonization, a polyclonal assay was developed for the target endophyte 5WS22E1. It was able to reliably detect the fungus in 500 ng subsamples of colonized needles. Seventeen months post-inoculation, 330 seedlings from 1235 inoculated were colonized. A random selection of 113 colonized seedlings was analyzed for rugulosin. Needles of most (90%) contained detectable concentrations of rugulosin. The range and distribution of the rugulosin concentrations was similar to that found in earlier tests done in growth chambers. [ABSTRACT FROM AUTHOR]

The impact of freezing temperatures and exposure times during budbreak and shoot elongation on 10-month-old containerized white spruce seedlings [ Picea glauca (Moench) Voss] was studied. Seedlings were exposed to 0, -2, -4, -6, -8 and -10°C for 0, 1, 2, 3, 4, 5 and 6 h at four stages of budbreak and shoot elongation (stage 1: unswollen bud; stage 2: swollen bud; stage 3: bud scales parted by emerging needles; stage 4: 1-5 cm of terminal shoot growth). Seedling and terminal bud survival, viability of first-year needles (developed before frost exposure), terminal shoot length, stem diameter and aerial dry mass were measured 90 days after freezing exposure. Frost severity had a much greater influence on seedling survival, damage and subsequent growth than exposure time. The bud development stage at which freezing temperatures were applied also affected survival and subsequent growth. [ABSTRACT FROM AUTHOR]

Populus balsamifera L., Betula papyrifera Marsh., Populus tremuloides Michx. and Picea glauca (Moench) Voss seedlings were grown in specialized pots that maintained a constant water-table height and allowed monitoring of water use by the tree/pot under high water-table conditions and different soil temperatures. The trees were grown at imperfectly and poorly drained water table conditions and at 5, 10 or 20°C soil temperature. In P. balsamifera , net assimilation and transpiration remained high under wet soil conditions and increased with higher soil temperatures. Populus balsamifera growth and leaf area development were severely restricted at soil temperatures of 5°C. Both B. papyrifera and P. tremuloides had low transpiration and pot level water-use rates at both water-table conditions and these did not significantly increase with increasing soil temperature. Picea glauca was negatively affected by high water tables but showed minimal response to soil temperature changes. The study suggests that P. balsamifera would be a good hydrological nurse crop to lower the water table when soils are warm, while B. papyrifera is likely to be a good nurse species in cool and imperfectly drained sites. [ABSTRACT FROM AUTHOR]

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO[sub 2] uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. [ABSTRACT FROM AUTHOR]

This study examined the effects of low-temperature storage of white spruce [Picea glauca (Moench) Voss] bareroot seedlings to determine whether the time between lifting and planting of spring-lifted seedlings could be extended. Seedlings were lifted from the nursery beds on May 4, 1994, and stored at- 2°C (frozen storage) and 4°C (cold storage) for 3, 5 and 7 weeks. Frozen storage of spring-lifted seedlings resulted in an increase in sugar levels in roots and needles that progressed with storage duration. Seedlings stored in cold storage maintained a relatively constant sugar content. Needle starch content decreased with storage duration in both frozen and cold storage. In the roots of cold-stored seedlings, starch content remained relatively constant during storage; however, in the frozen-stored seedlings, root starch levels sharply declined during the initial 3 weeks of storage. The levels of total non-structural carbohydrates (starch and sugars) decreased in both types of storage in needles, but not in roots. However, the decrease was more pronounced in the cold-stored than in the frozen-stored seedlings. Gas exchange, root growth potential and number of days to bud break were similar in frozen- and cold-stored seedlings planted in the greenhouse. However, following planting in the forest, cold-stored seedlings flushed buds earlier than did frozen-stored seedlings. The results indicate that tree nurseries could consider frozen storage of spring-lifted white spruce seedlings to facilitate lifting and planting schedules. [ABSTRACT FROM AUTHOR]

Whole root systems of 2-yr-old containerized white spruce [Picea glauca (Moench) Voss], black spruce [Picea mariana (Mill.) B.S.P.] and jack pine (Pinus banksiana Lamb.) seedlings, with intact root plugs, were exposed to various frost temperatures, which a preliminary test indicated would induce approximately 0 (control), 20, 40, 60, 80 and nearly 100% frost damage. Damage to root systems was evaluated using: (1) two measures of electrolyte leakage (relative conductivity and total tissue leakage after autoclaving); (2) water loss after pressurization; (3) chlorophyll fluorescence (F[sub v]/[sub Fm], maximal PSII photochemical efficiency) measured 4, 21 and 30 days after the beginning of seedling regrowth and (4) live root dry mass measured 21 days after the artificial frost and 60 days after the beginning of regrowth. Seedling survival and growth after the artificial frost were evaluated using live root dry mass measured after 60 days of regrowth and new shoot length, stem diameter, and root and shoot dry mass. Live root dry mass, dead tissue leakage, jack pine root water loss and fluorescence measurements were all significantly correlated with one or more of the growth variables and the number of significant correlations varied with species. Dead tissue leakage measurements appear to be the most promising method for evaluating root damage to 2-yr-old well-developed root systems of these species. [ABSTRACT FROM AUTHOR]

An index of tree growth based on the mean growth curve of black spruce shows that tree growth in the boreal forest of central Canada decreases linearly as the forest-tundra boundary is approached. A theoretical tree line is defined by black spruce growth data. The distribution of tree growth and the theoretical tree line indicate that the forest-tundra boundary is the mean summer position of the arctic front. The growth of white spruce is briefly considered, but because of a small sample size, no conclusions are drawn. [ABSTRACT FROM AUTHOR]