Search

We describe the spider communities collected by pitfall traps from forestry plantations at 16 areas across the UK, primarily planted with conifers, as part of the Biodiversity in Britain's Planted Forests research programme. The large collection of 13,863 identifiable individuals contained 191 species, mainly ones known to be associated with woodlands. The biggest source of variation in the data was a geographical gradient from the southeast to the northwest of the British Isles, presumably reflecting climatic conditions. The far northwestern sites held a relatively homogeneous assemblage typified by Micrargus apertus, while the southeastern sites held a more diverse mix of species. There was some evidence for tree species affecting the assemblage, with differences between the spiders of Sitka spruce and Norway spruce, also between Corsican pine and Scots pine. The age of forest was also influential, with highest diversity in the youngest stands. Overall, we suggest that these artificial plantations contribute to a surprising degree to our forest invertebrate biodiversity and merit further studies to elucidate the factors driving species assemblages within plantations of different tree species and of different ages. [ABSTRACT FROM AUTHOR]

Summary: Stone cells are a specialized, highly lignified cell type found in both angiosperms and gymnosperms. In conifers, abundance of stone cells in the cortex provides a robust constitutive physical defense against stem feeding insects. Stone cells are a major insect‐resistance trait in Sitka spruce (Picea sitchensis), occurring in dense clusters in apical shoots of trees resistant (R) to spruce weevil (Pissodes strobi) but being rare in susceptible (S) trees.To learn more about molecular mechanisms of stone cell formation in conifers, we used laser microdissection and RNA sequencing to develop cell‐type‐specific transcriptomes of developing stone cells from R and S trees. Using light, immunohistochemical, and fluorescence microscopy, we also visualized the deposition of cellulose, xylan, and lignin associated with stone cell development.A total of 1293 genes were differentially expressed at higher levels in developing stone cells relative to cortical parenchyma. Genes with potential roles in stone cell secondary cell wall formation (SCW) were identified and their expression evaluated over a time course of stone cell formation in R and S trees.The expression of several transcriptional regulators was associated with stone cell formation, including a NAC family transcription factor and several genes annotated as MYB transcription factors with known roles in SCW formation. [ABSTRACT FROM AUTHOR]

Our knowledge of the endophytic fungal community associated with needles of Sitka spruce (Picea sitchensis) is rather limited, which contrasts with the importance of this tree species for forestry in the UK. In our study, we focused on the detailed characterization of multiple isolates tentatively placed into the genera Nothophaeocryptopus and Rhizosphaera that were obtained from needles of Sitka spruce and co‐occurring Norway spruce (Picea abies) and Douglas fir (Pseudotsuga menziesii) at four sites in Scotland and Wales. After a thorough analysis of their phenotype and analysis of two nuclear regions (ITS rDNA and gene for β‐tubulin), we propose two species new to science and one new combination. Nothophaeocryptopus piceae was isolated from healthy green or brown needles from spruces and is currently known only as a sterile culture, but the taxonomic novelty is well supported by host affinity and results of molecular data analysis. Rhizosphaera minteri may also be distinguished based on the combination of host and molecular data, but morphologically, it is similar to R. pini. Finally, Hormonema merioides and R. pseudotsugae are found to be conspecific and a new combination R. merioides is proposed following the phylogenetic placement of this species. Our study highlights the importance of multiple approaches used in the identification of microfungi associated with coniferous needles. It is evident that morphologically identical fungi may represent distinct species differing in their host range and severity on the host. This study also provides a basis for future monitoring of these fungi associated with important coniferous forestry trees in the UK. [ABSTRACT FROM AUTHOR]

We investigated the genetic makeup of Lutz spruce, a natural hybrid between white and Sitka spruce on the Kenai Peninsula, Alaska. Microsatellites indicate 72% of individuals sampled had predominantly white spruce ancestry, whereas 14% had predominantly Sitka spruce ancestry; some individuals classified as white spruce had Sitka spruce plastid genotypes. As Picea mitochondria are maternally inherited and plastids are paternally inherited, it appears that white spruce was the ancestral seed parent of nearly all spruce on the western peninsula, whereas Sitka spruce alleles originated from pollen. Pollen records show that white spruce colonized the western peninsula ∼8500 YBP from glacial refugium, whereas Sitka spruce arrived on the eastern peninsula ∼4000 YBP after migrating up the Pacific coast. Our data suggest that Sitka spruce colonization west of the Kenai Mountains may have occurred not via seed dispersal but by long distance transport of wind-borne pollen and subsequent hybridization with established white spruce populations. Hybridization was an important mechanism that allowed Sitka spruce to expand the leading edge of its range in response to historical climate change. As the climate continues to warm, climate envelope modeling suggests Lutz spruce may ultimately displace white spruce on the western peninsula even as Sitka spruce is constrained to the eastern peninsula where it will continue to hybridize. [ABSTRACT FROM AUTHOR]

SUMMARY: Spruces (Picea spp.) are coniferous trees widespread in boreal and mountainous forests of the northern hemisphere, with large economic significance and enormous contributions to global carbon sequestration. Spruces harbor very large genomes with high repetitiveness, hampering their comparative analysis. Here, we present and compare the genomes of four different North American spruces: the genome assemblies for Engelmann spruce (Picea engelmannii) and Sitka spruce (Picea sitchensis) together with improved and more contiguous genome assemblies for white spruce (Picea glauca) and for a naturally occurring introgress of these three species known as interior spruce (P. engelmannii × glauca × sitchensis). The genomes were structurally similar, and a large part of scaffolds could be anchored to a genetic map. The composition of the interior spruce genome indicated asymmetric contributions from the three ancestral genomes. Phylogenetic analysis of the nuclear and organelle genomes revealed a topology indicative of ancient reticulation. Different patterns of expansion of gene families among genomes were observed and related with presumed diversifying ecological adaptations. We identified rapidly evolving genes that harbored high rates of non‐synonymous polymorphisms relative to synonymous ones, indicative of positive selection and its hitchhiking effects. These gene sets were mostly distinct between the genomes of ecologically contrasted species, and signatures of convergent balancing selection were detected. Stress and stimulus response was identified as the most frequent function assigned to expanding gene families and rapidly evolving genes. These two aspects of genomic evolution were complementary in their contribution to divergent evolution of presumed adaptive nature. These more contiguous spruce giga‐genome sequences should strengthen our understanding of conifer genome structure and evolution, as their comparison offers clues into the genetic basis of adaptation and ecology of conifers at the genomic level. They will also provide tools to better monitor natural genetic diversity and improve the management of conifer forests. The genomes of four closely related North American spruces indicate that their high similarity at the morphological level is paralleled by the high conservation of their physical genome structure. Yet, the evidence of divergent evolution is apparent in their rapidly evolving genomes, supported by differential expansion of key gene families and large sets of genes under positive selection, largely in relation to stimulus and environmental stress response. Significance Statement: The genomes of four closely related North American spruces indicate that their high similarity at the morphological level is paralleled by the high conservation of their physical genome structure. Yet, the evidence of divergent evolution is apparent in their rapidly evolving genomes, supported by differential expansion of key gene families and large sets of genes under positive selection, largely in relation to stimulus and environmental stress response. [ABSTRACT FROM AUTHOR]

Aphids can have a significant impact on the growth and commercial yield of spruce plantations. Here we develop a mechanistic deterministic mathematical model for the dynamics of the green spruce aphid (Elatobium abietum Walker) growing on Sitka spruce (Picea sitchensis (Bong.) Carr.). These grow in a northern British climate in managed plantations, with planting, thinning and a 60-year rotation. Aphid infestation rarely kills the tree but can reduce growth by up to 55%. We used the Edinburgh Forest Model (efm) to simulate spruce tree growth. The aphid sub-model is described in detail in an appendix. The only environmental variable which impacts immediately on aphid dynamics is air temperature which varies diurnally and seasonally. The efm variables that are directly significant for the aphid are leaf area and phloem nitrogen and carbon. Aphid population predictions include dying out, annual, biennual and other complex patterns, including chaos. Predicted impacts on plantation yield of managed forests can be large and variable, as has been observed; they are also much affected by temperature, CO2 concentration and other climate variables. However, in this system, increased CO2 concentration appears to ameliorate the severity of the effects of increasing temperatures coupled to worsening aphid infestations on plantation yield. [ABSTRACT FROM AUTHOR]

The Ansaldo A.1 "Balilla" biplane is of great historical interest, because it illustrates the level of development reached by the Italian aircraft industry during the last stages of World War I. To date, the airplane is kept in its original state, and it has never been restored. The aircraft is essentially made of wood and fabric. Wood in particular has been used in a very skilful way, making the airplane lightweight, yet elastic and resistant. In this work, the entire wooden structure of the aircraft was analysed, and the tree species were microscopically identified. Species belonging to six different genera have been identified. We found spruce in the frame, elm in the wing ribs, walnut in the propeller, alder in various plywood layers, rosewood in the outer layer of the decorative plywood, and pine in the tail rudder. The main structure of the aircraft was made of spruce, most likely a Sitka spruce, which was widely used for aircraft construction. The Ansaldo A.1 "Balilla" biplane is an excellent example of the wise use of wood before the revolution upon the boost in synthetic materials and represents an important historical and cultural heritage. [ABSTRACT FROM AUTHOR]

Norway spruce (Picea abies L. Karst) is one of the most important forest tree species with significant economic and ecological impact in Europe. For decades, genomic and genetic studies on Norway spruce have been challenging due to the large and repetitive genome (19.6 Gb with more than 70% being repetitive). To accelerate genomic studies, including population genetics, genome‐wide association studies (GWAS) and genomic selection (GS), in Norway spruce and related species, we here report on the design and performance of a 50K single nucleotide polymorphism (SNP) genotyping array for Norway spruce. The array is developed based on whole genome resequencing (WGS), making it the first WGS‐based SNP array in any conifer species so far. After identifying SNPs using genome resequencing data from 29 trees collected in northern Europe, we adopted a two‐step approach to design the array. First, we built a 450K screening array and used this to genotype a population of 480 trees sampled from both natural and breeding populations across the Norway spruce distribution range. These samples were then used to select high‐confidence probes that were put on the final 50K array. The SNPs selected are distributed over 45,552 scaffolds from the P. abies version 1.0 genome assembly and target 19,954 unique gene models with an even coverage of the 12 linkage groups in Norway spruce. We show that the array has a 99.5% probe specificity, >98% Mendelian allelic inheritance concordance, an average sample call rate of 96.30% and an SNP call rate of 98.90% in family trios and haploid tissues. We also observed that 23,797 probes (50%) could be identified with high confidence in three other spruce species (white spruce [Picea glauca], black spruce [P. mariana] and Sitka spruce [P. sitchensis]). The high‐quality genotyping array will be a valuable resource for genetic and genomic studies in Norway spruce as well as in other conifer species of the same genus. [ABSTRACT FROM AUTHOR]

Sitka spruce wood samples were subjected to different conditions of hydrothermal treatment at 140°C by varying the relative humidity and period of exposure. The control/reference and treated wood samples were evaluated using near infrared spectroscopy (NIRS), principal component analysis (PCA) and two dimensional correlation spectroscopy (2DCOS) in order to identify the structural modifications appearing during the treatment. Following this, the changes were reflected by the shifting of the bands position, modifications in bands intensities and width, as well as baseline offset. Higher modifications were identified in the 7400-6000 and 5100-4100 cm-1 regions assigned mainly to hemicelluloses and extractives, indicating that these components were the most susceptible to degradation in the present treatment conditions. Further, by PCA was possible to differentiate the modifications in the wood samples according to the time of treatment and relative humidity, while by 2DCOS was possible to identify the sequential order of modifications. [ABSTRACT FROM AUTHOR]

Longitudinal and flexural vibration tests were conducted using open-hole Sitka spruce specimens, and the effects of the size and location of the open hole on the measurement of the nominal Young's modulus and nominal shear modulus were investigated. The nominal elastic moduli often decreased as the size of the open hole increased, and the hole was located close to the mid-length of the specimen. However, the decreasing tendencies were characterised according to the direction along which the vibration was excited. To consider these phenomena, an empirical equation for deriving the nominal elastic modulus corresponding to the size and location of the open hole is proposed. The effects of the open hole were appropriately predicted using the proposed equation. [ABSTRACT FROM AUTHOR]

The shear moduli (SM) of solid wood in the longitudinal-radial (LR) and radial-tangential (RT) planes of Sitka spruce are extremely different from each other and were obtained via a torsional vibration (TV) test by varying the aspect ratios and conducting subsequent numerical analyses. The SM in both planes were accurate, when the aspect ratios of the specimens were appropriately selected, even though the SM around the torsional axis were extremely different from each other. [ABSTRACT FROM AUTHOR]

The incidence of longitudinal drought cracks in coniferous trees may increase as a consequence of climate change. While larger diameter trees are more prone to splitting, it is unclear why only some of the larger trees within the same stand typically suffer damage. Matched pairs of trees of the same size with and without cracks were studied in two adjacent pole-stage mixed stands of Sitka spruce/grand fir (Picea sitchensis/Abies grandis) and Sitka spruce/noble fir (Picea sitchensis/Abies procera) located in North-East Scotland. A range of attributes were measured on 15 damaged and undamaged trees of each species. Length and position of cracks on stems were also recorded, and annual ring width and latewood percentage measured on cores. Noble fir had significantly longer cracks and these were located higher in the stem than the other species. Fewer cracks formed on east-facing side of stems in all species suggesting that prevailing westerly winds may place greater tensile forces on the damaged sides of stems. A higher proportion of latewood (associated with higher tangential shrinkage) was found in the firs and may explain the greater incidence of cracking on grand and noble fir stems (13% and 16%, respectively) in comparison with Sitka spruce (3%). [ABSTRACT FROM PUBLISHER]

The Panel on Plant Health performed a pest categorisation of the Diprionid sawfly, Gilpinia hercyniae Hartig (Hymenoptera: Diprionidae), for the EU. G. hercyniae is a well-defined and distinguishable species, native to Europe but also present in North America, Japan, Mongolia, Korea and Pakistan, and recognised as a pest of spruce (Picea spp.). The pest is distributed in 19 Member States (MSs) of the EU. It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Greece, Ireland and the United Kingdom (Northern Ireland, Isle of Man and Jersey). Plants for planting of Picea spp. and soil and litter associated with Picea spp. are considered as pathways for this pest, which is also able to disperse by flight. The prepupae overwinter inside cocoons in the litter or in the foliage. In spring, the adults, mostly females emerge and lay 35-60 eggs per female in mature needles. The larvae feed on the mature needles through five instars. There are 1-3 generations per year; some of the prepupae undergo prolonged diapause for more than 1 year. The impact on Picea abies (= excelsa) is minimal, because only the needles of the previous years are attacked; however, outbreaks have occurred on non-native spruce, Picea glauca and Picea sitchensis. The pest is controlled everywhere by natural enemies, including nuclear polyedrosis viruses. The insects spread on plants for planting of Picea spp., with soil and litter associated with Picea spp., and by flight. The EU protected zones have a similar climate and similar host plants as the MS where G. hercyniae is established. All criteria assessed by EFSA for consideration as potential protected zone quarantine pest and as a potential regulated non-quarantine pest were met. [ABSTRACT FROM AUTHOR]

There is little information about the impacts of past Sitka spruce (Picea sitchensis [Bong.] Carr.) tree breeding on wood properties because the emphasis has traditionally been on improving stem form and growth rates. This study used both SilviScan and mechanical testing to investigate the radial variations in wood stiffness, bending strength, density and microfibril angle in defect-free samples taken from the first United Kingdom progeny trial to reach merchantable size. We tested for differences in these radial patterns of variation in half-sibling progeny of three plus trees originally selected for superior growth rate and stem form against a non-selected control. Large differences in all of the propertieswere observed with radial position, with properties generally being less desirable in the corewood. Significant undesirable differences between the improved families and the control were found for stiffness, strength and microfibril angle. There was no significant relationship between wood density and stiffness in samples taken from the inner part of the tree, where stiffness was more closely associated with microfibril angle. Overall, previous selections for growth rate and/or stem form have compromised timber properties. It is recommended that current breeding programmes focus on corewood stiffness to prevent further degradation in the wood properties of the future timber supply. [ABSTRACT FROM AUTHOR]

Pine plantations are prone to stem breakage due to high cyclic stress levels associated with hurricane force winds. Stress analytical and finite element simulation models were constructed of a representative profile of a (Sitka) Picea sitchensis tree. The profile surface stress (S) was determined due to the combined load of tree self-weight and hurricane wind speed. The results were complemented by reference to two other studies by other researchers that investigated the impact of fatigue cycles on failure (N) of pine wood and tree sway cycles to present a stem fatigue life prediction. The position of maximum surface profile stress and trunk fracture initiation location was ascertained from a non-uniform stress response. No stress uniformity along the trunk profile was observed for any wind-load case examined. The analytical model and finite element analysis of the P. sitchensis tree trunk profile revealed a statically adequate strength reserve factor of 1.4, which suggested another mode of failure was responsible. Fatigue life failure prediction was examined under cyclic and same-stress amplitude related to the hurricane wind speed of 33 m s-1. Predicted trunk fracture occurred in 2.6 hours, which dramatically reduced to two minutes with an increase in wind speed of only 1 m s-1. The calculated exposure time was similar to that recorded during Hurricane Hugo's transit in 1989. The time-to-failure prediction obtained by the method of analysis provided in this study seemed plausible, and that the profile associated with the P. sitchensis tree would suffer trunk breakage by low cycle fatigue failure. [ABSTRACT FROM AUTHOR]

The decomposition of harvest residues (brash) in managed forests has an important influence on the carbon (C) and nitrogen (N) stocks of these ecosystems. The brash input from thinning events in a 25-year-old Sitka spruce plantation was determined. A litter-bag method was used to determine the mass loss and decomposition rate of brash left on the forest floor. The changes in C and N concentrations and the C:N ratio of the needles and branches were also monitored as decomposition progressed for 2.5 years. Using the decomposition rate ( k) and estimated brash inputs, we then determined the total cumulative stock of C that the brash could supply to the deadwood pool over a 41-year rotation period. The three thinning events resulted in the addition of 37.99 t C ha and 0.61 t N ha to the forest floor. A significant mass loss of 44 % was recorded from brash decomposition bags after 2.5 years, with a rapid loss of 35 % in the first year, after which the rate of decomposition slowed. The k-value and residence time (95 % decomposition) were 0.311 year and 9.6 years, respectively. There was a 69 % increase in the N concentration of needles after 1.5 years, while an increase of 185 % in the N concentration of branches was recorded after 2.5 years. The C concentration (48.55 ± 0.20 %) did not differ significantly between the needles and branches over time. The accumulated C stock from decomposing brash at clearfell was estimated at 18.51 t C ha. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compared the canopy fauna of non-native spruce plantations with that of remnant native forests. [•] For all taxa, plantations supported a distinctly separate assemblage composition. [•] Native forests held twice as many beetle species and Diptera and Hemiptera families. [•] No differences in community structure were detected between 1st and 2nd rotation plantations. [•] Plantations were dominated by ultra-abundant aphid and midge populations. [ABSTRACT FROM AUTHOR]

Background: Cold acclimation in woody perennials is a metabolically intensive process, but coincides with environmental conditions that are not conducive to the generation of energy through photosynthesis. While the negative effects of low temperatures on the photosynthetic apparatus during winter have been well studied, less is known about how this is reflected at the level of gene and metabolite expression, nor how the plant generates primary metabolites needed for adaptive processes during autumn. Results: The MapMan tool revealed enrichment of the expression of genes related to mitochondrial function, antioxidant and associated regulatory activity, while changes in metabolite levels over the time course were consistent with the gene expression patterns observed. Genes related to thylakoid function were down-regulated as expected, with the exception of plastid targeted specific antioxidant gene products such as thylakoid-bound ascorbate peroxidase, components of the reactive oxygen species scavenging cycle, and the plastid terminal oxidase. In contrast, the conventional and alternative mitochondrial electron transport chains, the tricarboxylic acid cycle, and redox-associated proteins providing reactive oxygen species scavenging generated by electron transport chains functioning at low temperatures were all active. Conclusions: A regulatory mechanism linking thylakoid-bound ascorbate peroxidase action with "chloroplast dormancy" is proposed. Most importantly, the energy and substrates required for the substantial metabolic remodeling that is a hallmark of freezing acclimation could be provided by heterotrophic metabolism. [ABSTRACT FROM AUTHOR]

The vibrational properties of eight resonance boards made from Picea glehnii, Picea jezoensis, Picea spinulosa, and Picea sitchensis were analyzed. The modulus of elasticity and the vibration transmission velocity of the resonance board, the modulus of elasticity of the beam samples cut from the edge of the resonance board, and the vibration response time of the soundboard (TL, TR: times for the longitudinal and radial directions, respectively) were calculated. After the resonance boards were incorporated into the pianos, the sound intensity of loud (LL) and soft playing (LS), sound length (S), and the dynamic range of volume (Vd) were measured. Then the Influence of the vibrational properties of the resonance board on the acoustical quality of a piano was investigated preliminarily, and the results showed that the acoustical quality would improve notably with improvements in the vibrational properties in the y-direction of the resonance board, and that the TR affected acoustical quality more obviously than did TL. [ABSTRACT FROM AUTHOR]

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry 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.)

Differential patterns of introgression between species across ecological gradients provide a fine-scale depiction of extrinsic and intrinsic factors that contribute to the maintenance of species barriers and adaptation across heterogeneous environments., Introgression was examined for 721 individuals collected from the ecological transition zone spanning maritime to continental climates within the Picea sitchensis- Picea glauca contact zone using a panel of 268 candidate gene single nucleotide polymorphisms., Geographic clines showed a strong spatial relationship between allele frequencies and both distance from the ocean along major rivers and mean annual precipitation, indicating a strong role for environmental selection. Interspecific patterns of differentiation using outlier tests revealed three candidate genes that may be targets of long-term divergent selection between the parental species, although contemporary genomic clines within the hybrid zone suggested neutral patterns of introgression for these genes., This study provides a fine-scale analysis of locus-specific introgression, identifying a suite of candidate loci that may be targets of extrinsic or intrinsic selection, with broad application in understanding local adaptation to climate. [ABSTRACT FROM AUTHOR]

Interspecific hybridization may enhance the capacity of populations to adapt to changing environments, and has practical implications for reforestation. We use genome-wide estimates of admixture and phenotypic traits for trees in a common garden to examine the extent and direction of gene flow across a Picea hybrid zone, testing assumptions of the bounded hybrid superiority and tension zone models of hybrid zone maintenance. Seeds were collected from the ecological transition zone spanning from maritime to continental climates across the Picea sitchensis- P. glauca contact zone, and 721 trees were planted in a common garden experiment within the hybrid zone. Individuals were genotyped using a panel of 384 candidate-gene single nucleotide polymorphisms ( SNPs) putatively associated with adaptive traits in Picea, and phenotyped at age ten for height and autumn cold hardiness. Low interspecific heterozygosity in hybrids indicated that intrinsic reproductive barriers were too weak to prevent widespread recombination, although introgression appeared asymmetric with P. sitchensis dominating the zone. Whereas marker-based hybrid index was strongly correlated with climate and geography, phenotypic traits exhibited weak or no significant clines. Our results indicated that exogenous selection appeared to play a strong role in the distribution and structure of this hybrid zone, indicative of an environmentally determined bounded hybrid superiority model of hybrid zone maintenance, although endogenous mechanisms could not be ruled out. This study provides insight into the mechanisms underlying adaptation across ecologically transitional hybrid zones that will ultimately provide an additional tool in managing these economically important tree species. [ABSTRACT FROM AUTHOR]

The demand for trees for industrial application is growing steadily and not expected to plateau for at least two decades; consequently, the supply of wood must increase to meet this need. One method for increasing yield without compromising land requirements is to modify wood density. The current study uses a transcriptomic approach to identify the genes associated with wood density that are likely to be of value in Sitka spruce (Picea sitchensis (Bong.) Carr.) breeding programmes. Following extensive wood density analysis from a Sitka field grown clonal trial, three detailed microarray studies were conducted to compare the transcriptome of cambium and xylem tissue from contrasting density clonal lines. Twenty-five genes exhibited differential expression, with up to 50-fold differences in expression observed, in at least two of the three microarray experiments, and this was verified using real-time polymerase chain reaction. Identified genes included those involved in cell wall synthesis, transcriptional regulation and plant pathogen defence functional categories. A wide range of processes influence wood density, but this study has identified potential regulators in these pathways. Future studies can now use this information to understand natural variation in wood density, and manipulate the expression of these genes to improve timber quality and yield. [ABSTRACT FROM AUTHOR]

The article discusses the archives of the U.S. Army Spruce Production Division at the U.S. National Archives and Records Administration in Seattle, Washington. It notes that the division was headquartered in Vancouver, Washington and was created by the U.S. Army during World War I to increase timber production, particularly of Sitka spruce, for constructing airplanes. The author suggests that the records, which contain correspondences, could be particularly useful for genealogists because they shed light on soldiers' concerns such as furlough requests, sick leave, and promotions.

Light availability and infestation by the green spruce aphid (Elatobium abietinum) are key factors affecting the growth of Sitka spruce (Picea sitchensis) seedlings under a mature tree canopy, but their combined effect on seedling growth has not previously been quantified. A controlled outdoor experiment in which light levels (high light (HL): 100%, intermediate light (IL): 24%) and aphid infestation (absence/presence) were manipulated was conducted over 2 years to look at the effects on seedling growth and biomass distribution patterns. Aphid population assessments showed a significantly increased population density under IL, with three to four times higher cumulative aphid densities than that under HL. Defoliation rates of infested seedlings were directly related to aphid density. Total seedling biomass was strongly reduced in IL, and aphid infestation caused additional reductions in the biomass of particular components of the seedlings. Dry weight (DW) of older (≥1-year-old) needles in infested trees was significantly decreased in both years. Total root DW at the end of the second year was significantly affected by aphid infestation, and the reduction (14–18%) was similar in IL and HL treatments despite large differences in aphid density. Biomass distribution patterns in infested trees were similar to that of uninfested trees within each light treatment, indicating that the relative decreases in root biomass were accompanied by similar reductions in distribution to the above-ground parts of the seedlings. Leader extension growth of infested seedlings was reduced by 15–17% compared with uninfested seedlings under IL, whereas only a 2–3% reduction in leader extension of infested seedlings under HL was observed. The results showed that the response of seedlings to E. abietinum were primarily dependent on the light environment. The significant reduction caused by aphids on the total DW of older needles and roots, and on leader extension growth, does suggest the potential for effects to accumulate over time. [ABSTRACT FROM AUTHOR]

Mechanical tests were conducted on structural timber from a 37-year-old Sitka spruce (Picea sitchensis (Bong.) Carr), progeny trial located in Kershope Forest, Cumbria, UK. Values of modulus of rupture (MOR) and global modulus of elasticity (MOEG) in bending and density were compared between timber cut from four of the eight different seed lots which made up the experiment. Three of these seed lots were open-pollinated progeny of selected plus trees, while the fourth consisted of trees grown from an unimproved collection imported from the Queen Charlotte Islands (QCI) in British Columbia, Canada. The progenies from the plus trees were selected for their contrasting growth rates, stem form and wood density relative to the QCI control. Overall, the timber had characteristic values for density, MOR and MOEG consistent with the requirements for the C16 strength class. A significant difference in timber basic density was observed between two of the seed lots; however, there was no difference in MOR or MOEG between any of the seed lots. Most of the variation in strength properties in the study was attributable to differences between individual trees (»40 per cent) and individual pieces of timber from within a tree (»50 per cent), with only a small amount (⪅5 per cent) due to treatment differences. Results indicate that gains in merchantable log volume that have been achieved due to tree breeding do not appear to have been offset by a reduction in the mechanical properties of timber. [ABSTRACT FROM PUBLISHER]

This study describes the refinement and testing of a prototype scoring system for the visual assessment of stem straightness in Sitka spruce. The original system comprised a six-point scoring system from 1 (least straight) to 6 (straightest) based on an estimate of straight log lengths in the first 6 m of the stem. A longer log length category and additional score were added to the system to increase relevance to industry practice. The use of aids to measurement to improve the objectivity and accuracy of the visual assessment was tested. A purely visual assessment was as accurate as the measurement tools and was considerably quicker and easier to complete. A study to establish appropriate sampling levels indicated that between 60 and 100 trees should be assessed to obtain an acceptable estimate of the median and interquartile range of straightness scores for a stand. An investigation of the relationship between stem straightness score and yield of logs of different quality suggested that the scoring system may be used to differentiate between stands of different log quality. [ABSTRACT FROM PUBLISHER]

Abstract: The aim of this study was to compare the monoterpene content and distribution in litters and roots of three conifer species: Picea abies (L.) Karst, Picea sitchensis (Bong.) Carr. and Pinus sylvestris (L.). We analysed the monoterpene content of green needles, needle litter, F (fermentation) layer material and roots collected from monoculture plots. The rate of loss of monoterpenes from freshly fallen litter in the field was also studied at two monthly intervals over 10months, to assess the length of time that monoterpenes entering the litter layer remain. Monoterpene analysis was carried out by extracting homogenised samples in hexane and identifying and quantifying the resulting monoterpenes using gas chromatography with flame ionisation detection (GC–FID) and gas chromatography–mass spectrometry (GC–MS). Mean total monoterpene concentrations varied significantly between the three species examined (e.g. in freshly fallen litter 1531±96, 100±5 and 1175±122μgg−1 d. wt for P. abies, P. sitchensis and P. sylvestris); each species had distinctive and consistent monoterpene profiles associated with each type of tissue, and total monoterpene concentrations in green needles varied between individual trees of the same species, particularly for P. sitchensis. A substantial proportion of the monoterpene content of green needles remained in the needles after litter fall for P. abies (42%), P. sitchensis (11%) and P. sylvestris (30%). Although rates of monoterpene loss from needle litters varied initially (P. sylvestris > P. abies > P. sitchensis), the majority of the monoterpene content was lost after 4–6months. Maximum monoterpene emission rates from decaying litter were calculated of 39 (P. abies), 1.7 (P. sitchensis) and 39μgm−2 h−1 (P. sylvestris). Monoterpene concentrations in F layer material were very low (<10μgg−1 d. wt). Roots, particularly in P. sylvestris, represented a significant pool of monoterpenes (185±16, P. abies; 258±54, P. sitchensis; 2133±200μgg−1 d. wt, P. sylvestris). The monoterpene profile was similar between roots and litter of P. sylvestris (α-pinene most abundant), and for P. sitchensis, (limonene and α-pinene most abundant), although a different pattern was observed between needle litter (most abundant β-pinene) and roots (most abundant myrcene) of P. abies. The relatively high concentrations and different profiles of monoterpenes characterised in upper organic soil horizons here emphasise the need for their influence on soil ecological processes to be assessed. [Copyright &y& Elsevier]

Trees monitored for bark stripping over the previous 20 years were examined for timber defects by felling, then observing stain and rot in the split butt logs and strength testing wood samples. Logs (52 bark stripped, 28 controls) came from eight sites that had tree crops 28-39 years old; the logs were stratified for wound size (180 cm²), large wounds being rare. Many wounded logs had no stain or rot, but six of the 33 better-quality sawlogs were judged to be usable only for pulp. Modulus of elasticity and modulus of rupture were affected only at wounds and only in the sapwood there; at this position, mean stiffness and strength were both significantly reduced compared with control logs, with lowest means for logs with large wounds. Large wounds suffered a much greater incidence of stain and rot than small wounds, but their rarity meant that the calculated financial loss caused by the bark stripping estimated to be incurred over the whole rotation up to felling was only 3 per cent of the crop value. [ABSTRACT FROM AUTHOR]

The epiphytes of the trunks and branches of mature Sitka spruce (Picea sitchensis) trees were studied in twelve plantations containing open spaces (glades, rides and roads) in the east and southwest of Ireland. A pair of trees was studied at each site: one tree at the south-facing edge of an open space and one in the forest interior. Spruce trees were found to support a moderately diverse range of bryophytes and lichens, including two relatively rare bryophyte species. Clear patterns in vertical distribution were identified, with bryophyte richness and cover decreasing and lichen richness and cover increasing from the tree base to the upper trunk. The open spaces themselves did not appear to affect overall epiphyte diversity, with no significant differences in any of the diversity measures between edge and interior trees. The main effect of open spaces was on the epiphyte cover of the edge trees. This was related to increased light levels combined with the presence of live branches from close to ground level on the south sides of the edge trees, which produced optimum conditions for bryophytes at the tree base and lichens in the upper plots. However, this dense side-canopy negatively affected epiphyte diversity on the north sides of the edge trees. Further research is required to assess the effects of open spaces within forestry plantations on epiphyte diversity. [ABSTRACT FROM AUTHOR]

This paper presents results concerning climatic conditions affecting diameter growth of Sitka spruce introduced to Baltic Pomerania (Slawno Forest District). A relatively high homogeneity of tree-ring series permitted to construct on their basis the tree-ring chronology of Sitka spruce. A significant positive correlation was found between radial increments of Sitka spruce and air temperatures of winter and spring months (January-April) and a negative relationship between radial increments and temperature of May. This study also showed a distinctly positive correlation between diameter growth and precipitation in July and November of the previous year, and precipitation in February and in summer season (June-August) of the current year. During years with low precipitation in summer or low temperatures in winter and spring all trees produced narrow tree-rings. The proportion of air temperature and precipitation in variation of radial increment of Sitka spruce, ex- pressed by the coefficient of multiple determination, was 52%. [ABSTRACT FROM AUTHOR]

Changes in culturable aerobic bacterial communities of Sitka spruce stumps between 1 and 10 years old were investigated by isolating from the top 55 mm of the stumps. High numbers of bacteria were recovered from 15 mm below the surface of 1- and 2-year-old stumps, particularly in the sapwood, after which numbers dropped by an order of magnitude. Proportions of colony-forming units (cfu) capable of degrading cellulose and chitin increased with stump age, whereas siderophore producers decreased. Colony-forming units were grouped on the basis of 13 phenotypic characteristics, including colony form and colour, Gram stain, heat tolerance, siderophore production and production of various enzymes. Four groups of bacteria were identified; the proportions of the three Gram-negative groups varied with stump age. A quadratic relationship between bacterial diversity and stump age was detected using the Shannon–Weaver diversity index. Bacterial diversity was higher 15 mm below the stump surface than in deeper sampling points. The results are discussed in terms of the possible influence of prokaryotic organisms on the development of decay communities in Sitka spruce stumps. [ABSTRACT FROM AUTHOR]

Abstract: Analysis of expressed sequence tags (ESTs) and full-length (FL)cDNAs from species of spruce (Picea spp.) revealed a family of 35 unique dirigent proteins (DIR) and DIR-like proteins. Phylogenetic analysis indicates the spruce DIR and DIR-like genes cluster into three distinct subfamilies, DIR-a, DIR-b/d, and DIR-f, of a larger plant DIR and DIR-like gene family. Gene-specific primers were designed for 31 unique spruce DIR family genes, and closely related isoforms, and used to evaluate patterns of constitutive expression, as well as responses to herbivory by stem-boring insects (i.e., white pine weevil, Pissodes strobi) in bark tissue and defoliating insects (i.e., western spruce budworm, Choristoneura occidentalis) in green apical shoots. Furthermore, meta-analysis of microarray gene expression data obtained from a series of independent experiments using the same 16.7K cDNA array platform identified several distinct expression clusters of the spruce DIR transcriptome closely matching phylogenetic clusters of sequence similarity. Members of the DIR-a family, which also contains functionally characterized DIR from other plant species, are most prominent for their induced response to feeding by weevils on Sitka spruce bark. [Copyright &y& Elsevier]

Three genetically distinct groups of Sitka spruce, open-pollinated Queen Charlotte Island provenance, A13 selected seed and M0044 half-sib mixture, were wounded alone or wounded and inoculated with Heterobasidion annosum sensu stricto on the lower stems. Growth of the pathogen and lesion formation was compared in the three genetic groups after treatment. No differences in the rate of colonization of the three genetic groups were observed over a 40 day period; lesion lengths in the bark and sapwood correlated closely. Moreover, lesions were considerably longer in inoculated plants than in those which were wounded only. No correlations were found within or between host genetic groups in the numbers or total areas of resin canals present in the first 18 mm from the wound in bark tissues for the three host genetic groups. Formation of the ligno-suberized boundary zone (LSZ), however, was inhibited in the bark of inoculated plants, being first detected later and at a greater distance from the wound/inoculation point in the presence of H. annosum than in plants that were wounded only. Thickness of the suberin cell layers within the LSZ of M0044 plants was greater in wounded and inoculated, than in wounded only plants. The significance of these findings in relation to detecting spruce genotypes potentially resistant to H. annosum is discussed. [ABSTRACT FROM AUTHOR]

We report diurnal variations in 13C discrimination (13Δ) of Picea sitchensis (Bong.) Carr. branches measured in the field using a branch chamber technique. The observations were compared to predicted 13Δ based on concurrent measurements of branch gas exchange. Observed 13Δ values were described well by the classical model of 13Δ including isotope effects during photorespiration, day respiration and CO2 transfer through a series of resistances to the sites of carboxylation. A simplified linear of model 13Δ did not capture the observed diurnal variability. At dawn and dusk, we measured very high 13Δ values that were not predicted by either of the said models. Exploring the sensitivity of 13Δ to possible respiratory isotope effects, we conclude that isotopic disequilibria between the gross fluxes of photosynthesis and day respiration can explain the high observed 13Δ values during net photosynthetic gas exchange. Based on the classical model, a revised formulation incorporating an isotopically distinct substrate for day respiration was able to account well for the high observed dawn and dusk 13Δ values. [ABSTRACT FROM AUTHOR]

This study presents the impacts of clear-cutting and site preparation on soil and needle 15N-fractionation of Scots pine (Pinus sylvestris, L.) and Norway spruce (Picea abies (L.), Karst). Three microsites on different methods of site preparation were used: (i) mound (broken O/E/B horizons piled upside down over undisturbed humus), (ii) deep (exposed C-horizon) and (iii) shallow (exposed E/B horizon). We found significant differences between species, between closed forest and clear-cuts as well as between different site preparations. For instance, in the context of interspecific variations, the mean needle nitrogen concentrations of both seedlings (1.15,±0.10 %) and mature (1.09,±0.07 %) pine trees were significantly higher compared to corresponding needle concentrations of seedlings (0.88,±0.06 %) and mature trees (0.79,±0.02 %) of spruce. Similarly, we observed significantly more 15N-enriched needles of mature spruces (-4.0,±0.20 ‰) as well as of seedlings (-5.0,±0.11 ‰) relative to that of mature pine needles (-5.6,±0.10 ‰) and seedlings (-6.0,±0.31 ‰). These variations were assumed to be caused by the variation in mycorrhizal associations between the species. We assume that the proportion of mycorrhizal N-uptake of pines might have been larger than that of spruce. Regarding the clear-cut effects on N and 15N of both tree species, we observed that, in the mature natural stand, needle N concentrations of both pine (1.09,±0.07 %) and spruce (0.79,±0.02 %) tree species did not change significantly after clear-cutting (pine: 1.01,±0.06 %; spruce: 0.74,±0.04 % ). However, clear-cutting resulted in the significant increase in needle 15N natural abundance of both pine (-2.70,±0.06 ‰) and spruce (-2.09,±0.05 ‰) in comparison to that of natural stand (pine:-5.60,±0.10 ‰; spruce:-4.00,±0.20 ‰), which is assumed to be due to the increased level of nitrification and leaching of nitrate after clear-cutting. In the context of site preparation methods, soil and needle N were observed to be more 15N-enriched in deep and shallow treatment sites compared to that of closed forest site and untreated clear-cut site, which indicated that the main source of N uptake seems to be mainly directly from the soil of the corresponding horizons of mineral soil with higher δ15N.†Revised version of a paper presented at the VIII Isotope Workshop of the European Society for Isotope Research (ESIR), 25–30 June 2005, Leipzig-Halle, Germany [ABSTRACT FROM AUTHOR]

Abstract: The decomposing roots of harvested trees are a potential source of nutrients for new trees on both conventional and whole-tree harvested clearfell sites. Roots contain significant reservoirs of nutrients, but little is known about the magnitude and rate of their release. The aim of this study was to use stable isotope techniques in a model system to trace nutrients released by decomposing roots. Labelled biomass was obtained by growing Sitka spruce (Picea sitchensis (Bong.) Carr.) seedlings with a generous or poor nutrient supply containing elevated 15N, 41K, 26Mg and 44Ca. Labelled trees were re-potted in sand and in two contrasting soils types to remove them from the enriched isotope supply. After re-potting, the labelled above-ground biomass was harvested, removed and used in a separate study described previously (Part I of II). In the study described here (Part II of II), new Sitka spruce seedlings were planted alongside the labelled root systems. A full destructive harvest was undertaken after one growing season. Enriched 15N, 41K, 26Mg, and 44Ca were recovered in the new seedlings in both sand and soils. The elevated amounts of 15N, 41K, 26Mg and 44Ca recovered in new seedlings indicate that nutrients released from decomposing roots can make a direct contribution to the growth of new trees on restock sites. The success of this model system will provide guidance for the application of similar techniques in field experiments. [Copyright &y& Elsevier]

This paper reports on the effect of wind loading below damaging strength on tree mechanical and physical properties. In a wind-exposed Sitka spruce stand in western Scotland, 60 trees at four different levels of wind exposure (10 m, 30 m, 50 m, 90 m from edge) were characterized for stem and crown size and shape and mechanical properties, including structural Young's modulus (Estruct) natural frequency, and damping ratio. Estruct increased from the stand edge to the mid-forest, but with a large inter-tree variation. Swaying frequency and damping ratio of the trees also increased with distance from edge. Wind-exposed edge trees grew shorter, but more tapered with an overall lower Estruct, allowing for greater flexural stiffness at the stem base due to the larger diameter and for higher flexibility in the crown region of the stem. The trees at the middle of the stand compensated for their increased slenderness with a higher Estruct. Thus, for the different requirements for wind-firmness at stand edge and mid- forest, an adapted combination of tree form and mechanical properties allows the best withstanding of wind loads. The results show the requirement to understand the different strategies of trees to adapt to environmental constraints and the heterogeneity of their growth reactions in response to these strategies. [ABSTRACT FROM AUTHOR]

Abstract: The large pine weevil (Hylobius abietis) is a major pest of young conifer and broadleaf transplants on restock sites in the UK. The objectives of this study were two-fold. The first was to test the effectiveness of two methods of application of the entomopathogenic nematode Steinernema carpocapsae in infecting the various life stages of the weevil in Sitka spruce (Picea sitchensis) stumps. The second objective was to investigate the importance of distribution and development of each of the weevil life stages in order to improve our understanding of factors influencing infection by S. carpocapsae. The method of nematode application on 24 July 1997, as well as the distribution and life stage of H. abietis within the stump and root system of Sitka spruce, were all shown to affect nematode efficacy as a field-based biological control agent. In contrast, the time of felling of the trees from July to September 1995 to create these stumps did not result in different rates of nematode infection of H. abietis in the stumps 2 years post-felling, but did influence development of the pest. H. abietis larvae were more widely distributed throughout the stump and root system than pupae, callow adults and pre-emergent adults that tended to be in the upper regions of the soil and close to the stump bole. Callow adults were highly susceptible to nematode infection, but larvae and older adults were not. Pupae had similar infection to larvae possibly due to late nematode application, as laboratory studies showed similar infection rates to callow adults. The results showed that S. carpocapsae tended to remain near the point of application, with the incidence of H. abietis infection declining with increasing distance from the stump and with increasing soil depth. The distribution of the most susceptible stages was, therefore, optimal for maximum nematode infection. At the time of the trial, susceptible H. abietis life stages comprised only 14–20% of the H. abietis population and the low level of control achieved (5.2–18.3%) reflects the differential susceptibility of these stages. The short duration of the callow adult and pupal stages, combined with the variation in development rates, indicated a fairly narrow application window in which to maximise infection rates. Timing of nematode treatment to proceed or better coincide with the susceptible stages of the lifecycle, multiple applications and/or increased dose rates of nematodes would probably have increased the overall level of control. Of the two application techniques used the subsurface drench was more efficient than the surface spray application, the former targeting a greater proportion of the susceptible life stages of H. abietis. [Copyright &y& Elsevier]

Abstract: We examined the effects of forest clearfelling on the fluxes of soil CO2, CH4, and N2O in a Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation on an organic-rich peaty gley soil, in Northern England. Soil CO2, CH4, N2O as well as environmental factors such as soil temperature, soil water content, and depth to the water table were recorded in two mature stands for one growing season, at the end of which one of the two stands was felled and one was left as control. Monitoring of the same parameters continued thereafter for a second growing season. For the first 10 months after clearfelling, there was a significant decrease in soil CO2 efflux, with an average efflux rate of 4.0gm−2 d−1 in the mature stand (40-year) and 2.7gm−2 d−1 in clearfelled site (CF). Clearfelling turned the soil from a sink (−0.37mgm−2 d−1) for CH4 to a net source (2.01mgm−2 d−1). For the same period, soil N2O fluxes averaged 0.57mgm−2 d−1 in the CF and 0.23mgm−2 d−1 in the 40-year stand. Clearfelling affected environmental factors and lead to higher daily soil temperatures during the summer period, while it caused an increase in the soil water content and a rise in the water table depth. Despite clearfelling, CO2 remained the dominant greenhouse gas in terms of its greenhouse warming potential. [Copyright &y& Elsevier]

The anchorage of 40-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) trees grown in a plantation on a steep (ca. 30°) slope was compared with that of trees grown on an adjacent horizontal area. There was similar gleyed mineral soil on the sloping and horizontal areas. Trees were mechanically overturned using a winch, and anchorage was quantified by measuring load, stem angle, and tree dimensions. Trees on the slope were overturned upslope, downslope, or across-slope. Critical turning moments were calculated around the tree base and the actual hinge point. Critical wind speeds required to uproot or snap trees in this stand were modelled to compare the vulnerability of trees to upslope and downslope winds. No overall difference in anchorage was found between trees grown on the horizontal and sloping parts of the site. However, for trees on the slope, those pulled upslope showed significantly more resistance to overturning for a given stem mass than those pulled downslope. Critical turning moments calculated at the hinge point were smaller than those calculated at the stem base, but differences were small and had no effect on the comparison between treatments. Critical wind speeds for uprooting were estimated to be 28 m·s–1 for an upslope wind and 24 m·s–1 for a downslope wind on this site. The implications of these results are discussed in relation to windthrow-risk modelling and forest soil conservation. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated levels of genetic diversity and population differentiation among Sitka spruce (Picea sitchensis) populations classified as core or peripheral based on ecological niche, and continuous or disjunct based on species distribution. Large numbers of trees (N=200) were sampled from each of eight populations to evaluate the distribution of rare as well as common alleles across the species range. Codominant alleles for eight sequence-tagged site loci were classified based on frequency and geographic distribution in order to develop appropriate sampling strategies to target specific classes of alleles. An important finding of this study is the similarity in genetic diversity as measured by expected heterozygosity between core populations (mean HE=0.58) and peripheral populations (mean HE=0.56). However, there was significant inbreeding in peripheral (FIS=0.17) but not in core (FIS=0.03) populations. Large differences in gene flow estimates were observed between core (Nm=9.0) and peripheral populations (Nm=3.5). Irrespective of population classification, over 75% of the alleles were common and widespread. Only one allele was classified as rare and localized, and this allele was limited to one core, disjunct and two peripheral, disjunct populations. There was stronger evidence of past bottlenecks in peripheral, disjunct populations than in core, continuous populations. Results are used to suggest sampling strategies for capture of maximum level of genetic diversity and conservation of rare alleles. The conservation of peripheral, particularly disjunct, populations as well as populations in putative glacial refugia may present the best opportunity for conserving rare alleles. [Copyright &y& Elsevier]

Research involving the silviculture and genetic improvement of Sitka spruce (Picea sitchensis (Bong.) Carr.) is the most advanced of any tree species in Great Britain. Best practice advice and improved planting stock material are now available as growers attempt to maximize their returns according to their objectives. This paper reviews the various advances made in silvicultural and tree breeding research and summarizes the main lessons that have been learnt and the time scales involved. From this analysis it is possible to gain a clearer picture of the limits that silviculture and genetic improvement have for further tree improvements. The need for a combined approach in order to maximize the benefits of good silviculture and genetically improved material is emphasized. Recommendations have then been proposed for hardwood tree improvement in the light of the experience with Sitka spruce. In particular, there is the need for silviculture and tree breeding to address improvement of timber quality rather than purely vigour, and the use of parallel breeding strategies to enable improved material to come onto the market as quickly as possible. The need to make greater use of registered seed stands and untested clonal seed orchards, based on plus trees, as well as a more thorough system of progeny testing and selection is also discussed. [ABSTRACT FROM AUTHOR]

Stem-boring insects and methyl jasmonate (MeJA) are thought to induce similar complex chemical and anatomical defenses in conifers. To compare insect- and MeJA-induced terpenoid responses, we analyzed traumatic oleoresin mixtures, emissions of terpenoid volatiles, and expression of terpenoid synthase (TPS) genes in Sitka spruce (Picea sitchensis) following attack by white pine weevils (Pissodes strobi) or application of MeJA. Both insects and MeJA caused traumatic resin accumulation in stems, with more accumulation induced by the weevils. Weevil-induced terpenoid emission profiles were also more complex than emissions induced by MeJA. Weevil feeding caused a rapid release of a blend of monoterpene olefins, presumably by passive evaporation of resin compounds from stem feeding sites. These compounds were not found in MeJA-induced emissions. Both weevils and MeJA caused delayed, diurnal emissions of (-)-linalool, indicating induced de novo biosynthesis of this compound. TPS transcripts strongly increased in stems upon insect attack or MeJA treatment. Time courses and intensity of induced TPS transcripts were different for monoterpene synthases, sesquiterpene synthases, and diterpene synthases. Increased levels of weevil- and MeJA-induced TPS transcripts accompanied major changes in terpenoid accumulation in stems. Induced TPS expression profiles in needles were less complex than those in stems and matched induced de novo emissions of (-)-linalool. Overall, weevils and MeJA induced similar, but not identical, terpenoid defense responses in Sitka spruce. Findings of insect- and MeJA-induced accumulation of allene oxide synthase-like and allene oxide cyclase-like transcripts are discussed in the context of traumatic resinosis and induced volatile emissions in this gymnosperm system. [ABSTRACT FROM AUTHOR]

For determining the shear stress/shear strain relation, we conducted asymmetric four-point bending tests using a side-tapered specimen. Sitka spruce (Picea sitchensis Carr.) was used for the testing material. Rectangular beams with various depths were prepared and symmetric tapers were cut on both side surfaces of the beam so that the failure by shearing preceded that by bending. Asymmetric four-point bending tests were performed under a constant span length condition, and the shear stress/shear strain relations were obtained. In addition to the asymmetric bending tests, Iosipescu shear tests were conducted and the results were compared. The shear stress/shear strain relation could be obtained by the asymmetric four-point bending tests more easily and effectively than by the Iosipescu shear tests when the specimen had a proper configuration. Hence, we concluded that the asymmetric four-point bending test of a side-tapered specimen is promising for determining the shear stress/shear strain relation of wood. [ABSTRACT FROM AUTHOR]

Few microsatellite markers have been specifically developed for Picea sitchensis. In January 2004 the appearance of over 10 000 sequences of expressed regions of DNA from P. glauca in GenBank presented an opportunity for the development of additional microsatellite markers in Sitka spruce. Mono- and dinucleotide repeat sequences were located in these sequences and primers were designed around these regions. Amplification was attempted in Sitka material from a broad geographical range and the level of polymorphism was assessed. Primers were also tested in progeny of a controlled cross. Nine polymorphic loci that demonstrated Mendelian inheritance in Sitka were discovered in this study. [ABSTRACT FROM AUTHOR]

This paper describes an evaluation of the potential of medium resolution (20–30 m pixel size) satellite data to monitor the growth of Sitka spruce (Picea sitchensis Bong. Carr.) plantations in the UK. The aim is to develop a cost-effective methodology to allow crops to be monitored by remote sensing and, in particular, to provide a mechanism to identify compartments that fail to establish as commercially viable crops. The method used involves predicting forest variables from optical reflectance imagery and field observations using generalized linear modelling. The first stage of this process is to establish the quantitative relationship between forest structure and reflectance data from the Landsat ETM+ and SPOT 4 HRVIR sensors. This was investigated for 25 compartments of Sitka spruce ranging in age from 2 to 17 years. The generalized linear models used showed that mean height is most strongly correlated with reflectance data. There is, however, no relationship between tree density and reflectance data. Interestingly, despite the differences in spatial resolution between Landsat and SPOT data, the predictive models derived were almost identical. Independent field checking of these models indicates that the root mean square error of crop height predictions is 1.5 m. The study suggests that by using repeated satellite surveys, tree growth can be monitored for very low cost per unit area and data can easily be integrated into a GIS (Geographical Information System) allowing foresters to interrogate and visualize the predictions over large areas. [ABSTRACT FROM AUTHOR]

This study examined the wood properties of 24-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) progenies with highly contrasting growth rates. The progenies were established as part of a breeding programme to improve growth rate and stem form. Trees from three progenies were selected with a high growth rate relative to an unimproved control of directly imported material from the Queen Charlotte Islands (QCI), British Columbia, Canada. Trees from a further three progenies were selected that displayed a similar growth rate to the QCI control. At the time of sampling, the fastgrowing progenies had a mean volume gain over the QCI and slow-growing progenies of ~70 per cent. Trees from the fast-growing progenies were found to have significantly larger branches, less latewood, and more compression wood in comparison with the QCI control and the slow-growing progenies. On the other hand, trees from the fast-growing progenies had a smaller grain angle than the QCI control. While fast-growing progenies had lower wood density than the control, this was not significantly different. These findings suggest that, in general, the criteria used to select Sitka spruce trees in the forest as potential candidates for the breeding population would indeed lead to significant improvements of the growth performance and grain angle from improved planting stock. Breeders need to be aware, however, of possible negative influences of such selection criteria on other stem and wood properties known to influence wood strength. [ABSTRACT FROM AUTHOR]

Sitka spruce (Picea sitchensis) is highly susceptible to leader damage by the white pine weevil (Pissodes strobi). Population differences for resistance have been previously noted from older IUFRO provenance trials both from hybrid sources (the natural hybrids of Sitka and white spruce), but also in populations of pure Sitka from dryer ecological zones. It was postulated that this resistance might be common within this high hazard ‘dry’ zone because of potentially higher selection pressures from increased weevil density. Results from a population transect of this zone, established as an openpollinated progeny/provenance trial, show that resistance is not broadly based but is centred about one of the original IUFRO resistant sources. Although hazard-zone differences were significant, sources within zone, had the strongest effect in our model; particularly evident was a strongly defined population effect around the original IUFRO source. Heritability estimates for resistance were also affected by this strong source population effect. [ABSTRACT FROM AUTHOR]