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The productivity of economically valuable focal trees in mixtures is often improved by inclusion of lower‐value nursing species, but the mechanisms underpinning such effects are poorly resolved. This gap in understanding limits the capacity to develop efficient planting strategies for forests and woodlands to contribute to net‐zero and other critical ecosystem functions. Here, we undertook a plant–soil feedback experiment to test the hypothesis that feedback effects improve the biomass of Sitka spruce [Picea sitchensis (Bong.) Carr] in soil conditioned by monocultures of heterospecific nurse species, and a mixture comprising Sitka spruce and heterospecifics, compared to soil conditioned by only Sitka spruce. Sitka spruce saplings had greater biomass in soil conditioned by Scots pine monocultures (Pinus sylvestris L.) and the mixture compared to their own soil or soil conditioned by silver birch (Betula pendula Roth). Statistical models showed that colonization of ectomycorrhizal fungi on tree roots in the feedback phase was positively related to seedling biomass, and significantly influenced plant growth strategy. Soil inorganic nitrogen concentrations were strongly affected by monocultures and mixtures in the conditioning phase, but these effects were not related to biomass of seedlings in the feedback phase. However, the positive associations among microbial biomass nitrogen, extractable ammonium in soil, and the activity of the nitrogen‐degrading enzyme N‐acetylglucosaminidase may influence seedling biomass in the longer‐term by stimulating nitrogen cycling. Synthesis and applications. Our findings show that in the crucial early phases of tree growth, plant–soil feedback plays an important role in shaping productivity of Sitka spruce and the nitrogen cycle in forest soils, the latter which may have important consequences for tree biomass in the longer‐term. Our findings demonstrate the importance of the nursing effect in the early stages of plant growth and provide a mechanistic explanation both for long‐held observations of nursing effects in forestry systems and for biodiversity effects in natural woodlands. The nursing effect was largely driven by the activity of symbiotic ectomycorrhizal fungi, and therefore it is important for practitioners to ensure nursing species monocultures or mixtures support ectomycorrhizal fungi that are compatible with high‐value target species. [ABSTRACT FROM AUTHOR]

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]

Sitka spruce (Picea sitchensis (Bong.) Carr.), is a highly valuable commercial tree species in Ireland, UK and elsewhere in Europe but there is relatively little information available in relation to the performance of improved material. The primary objective of this study was to explore the genetic variation in competitive ability and determine how a spatial model improved the accuracy of genetic estimates over time for Sitka spruce. To achieve this, the study employed competition index (Hegyi's I) and spatial analysis on height and diameter data from genetic improvement trials in Ireland. A total of 54 half-sib families of Sitka spruce were included in the study. The trials had been established to identify superior genotypes among the plus trees which had been included in the improvement programme in Ireland. The study revealed that spatial heterogeneity significantly affects the genetic estimates for Sitka spruce. The results indicated that spatial analysis could provide valuable insights into the genetic trials of Sitka spruce and improve the accuracy of genetic evaluations. Heritability increased by 104% for diameter at breast height (DBH) using a spatial analysis approach, compared with a more traditional non-spatial model approach. It was found that thinning practices can affect the response of genetic performance to spatial heterogeneity. In addition, genetic variation in competitive ability was observed. The results highlight the importance of considering spatial dependence in the design but more importantly in the analysis of genetic trials and provides a framework for future research on the genetic improvement of Sitka spruce populations. [ABSTRACT FROM AUTHOR]

Natural regeneration can reduce costs compared with replanting. However, its use requires knowledge about how either active or passive management will affect the balance between quality and quantity in the timber supply. This study aimed to quantify the effects of respacing on volume recovery and wood properties. Two British forest experiments using Picea sitchensis with various respacing distances and an un-respaced control were assessed 21–22 years after the treatments were applied. Tree dimensions were measured and used to quantify slenderness, merchantable volume, and sawlog volume. Wood properties were assessed on a sub-sample using mechanical testing. Generalised linear mixed models were used to examine differences between treatments and sites. Respacing decreased slenderness and increased relative sawlog volume and branch size. Wider respacing reduced wood strength and the widest respacing reduced wood stiffness. Respacing did not affect wood density. However, at the relatively low productivity sites considered here, respacing to 2.1 m represented the best compromise for current markets. In summary, not respacing improved some wood properties but reduced tree stability and the proportion and volume of sawlogs, which will negatively affect forest value. [ABSTRACT FROM AUTHOR]

Winter storage of seedlings in freezers reduces the amount of heat sum available for growth in the following growing season compared to seedlings stored outdoors. To test the effects of a reduced growing period on the autumn frost hardiness of the six species most used in Icelandic afforestation, seedlings were stored outdoors or in a freezer during winter. In spring, the seedlings were planted on 24 May, 7 June, 21 June, and 5 July, and the frost hardiness of all treatments was tested on 12 and 26 September. In general, the probability of freezing damage increased with a later planting date, with outdoor-stored seedlings having the lowest probability of damage. The timing of frost events was of great importance; the later the freezing date, the less damage was observed. Growth cessation occurred at different times for each species, and they responded differently to the reduced heat sum. Lodgepole pine and birch accumulated the most frost hardiness in September. Sitka spruce had less autumn frost hardiness than Lutz spruce. Hybrid larch accumulated less frost hardiness than Russian larch and was most sensitive to the reduced heat sum. The results can be used to determine which species should be prioritised in frozen storage with regard to Iceland's short growing season. [ABSTRACT FROM AUTHOR]

Summary: Endemic species of ectomycorrhizal fungi (EMF) are found throughout many biomes, but it is unclear whether their localized distribution is dictated by habitat filtering or geographical barriers to dispersal.We examined community composition (via long‐read metabarcoding) and differences in sporocarp nutrition between endemic and cosmopolitan EMF species across perhumid temperate rainforests of British Columbia, characterized by soils with high nitrogen (N) supply alongside low phosphorus (P) and cation availability.Endemic EMF species, representing almost half of the community, had significantly greater sporocarp N (24% higher), potassium (+16%), and magnesium (+17%) concentrations than cosmopolitan species. Sporocarp P concentrations were comparatively low and did not differ by fungal range. However, sporocarp N% and P% were well correlated, supporting evidence for linkages in N and P acquisition. Endemics were more likely to occur on Tsuga heterophylla (a disjunct host genus) than Picea sitchensis (a circumpolar genus). The Inocybaceae and Thelephoraceae families had high proportions of endemic taxa, while species in Cortinariaceae were largely cosmopolitan, indicating some niche conservatism among genera.We conclude that superior adaptive traits in relation to perhumid soils were skewed toward the endemic community, underscoring the potentially important contribution of these localized fungi to rainforest nutrition and productivity. [ABSTRACT FROM AUTHOR]

In species with large and complex genomes such as conifers, dense linkage maps are a useful resource for supporting genome assembly and laying the genomic groundwork at the structural, populational, and functional levels. However, most of the 600+ extant conifer species still lack extensive genotyping resources, which hampers the development of high-density linkage maps. In this study, we developed a linkage map relying on 21,570 single nucleotide polymorphism (SNP) markers in Sitka spruce (Picea sitchensis [Bong.] Carr.), a long-lived conifer from western North America that is widely planted for productive forestry in the British Isles. We used a single-step mapping approach to efficiently combine RAD-seq and genotyping array SNP data for 528 individuals from 2 full-sib families. As expected for spruce taxa, the saturated map contained 12 linkages groups with a total length of 2,142 cM. The positioning of 5,414 unique gene coding sequences allowed us to compare our map with that of other Pinaceae species, which provided evidence for high levels of synteny and gene order conservation in this family. We then developed an integrated map for P. sitchensis and Picea glauca based on 27,052 markers and 11,609 gene sequences. Altogether, these 2 linkage maps, the accompanying catalog of 286,159 SNPs and the genotyping chip developed, herein, open new perspectives for a variety of fundamental and more applied research objectives, such as for the improvement of spruce genome assemblies, or for marker-assisted sustainable management of genetic resources in Sitka spruce and related species. [ABSTRACT FROM AUTHOR]

The ongoing loss of red‐listed coastal heathlands is a threat to biodiversity and cultural heritage legacies throughout the Atlantic coastal regions of Europe. It is possible to restore degraded and afforested heathlands, but restoration interventions are often labour‐intensive and costly, and the outcome of specific restoration actions are not well documented. We assess the efficiency of restoring coastal heathlands through natural succession (i.e. 'passive restoration') after removal of Sitka spruce Picea sitchensis (Bong.) Carr. plantations. The study was replicated on two neighbouring islands in a nature reserve in Western Norway. Low‐intensity free‐range sheep grazing was implemented as part of the reserve management plan. Furthermore, we tested the effect of leaving the clear‐felled woody material as chips on site, this being a cost‐efficient strategy on islands. Succession was monitored 1, 2, 4/5 and 8 years after clear‐felling, and revegetation of vascular plants and bryophytes was compared to target heathland vegetation. Surprisingly, we found different successional trajectories on the two islands. Species composition on one island approached target heathland vegetation during succession, but not on the other. Wood chips reduced species richness and slowed the restoration process, but these negative effects were only short‐term (<8 years). Differences in seed bank composition and soil conditions due to land use may explain the deviating successional trajectories on the two islands. We also found that management actions beyond clear‐felling and introducing sheep grazing are necessary due to the rapid seed regeneration of the Sitka spruce. [ABSTRACT FROM AUTHOR]

Precommercial thinning and tree pruning are frequently used together to improve timber quality and wildlife habitat in even-aged Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla) stands. Thinning enhances crop tree growth and understory plant production; however, the benefits and drawbacks of tree pruning have received less attention. Tree pruning was investigated in two long-term experiments on the Tongass National Forest, Alaska, USA. Experiment 1 tracked four uniformly thinned sites for ~30 years that received 2.4, 3.6, and 5.2 m lift, and no pruning treatments. Experiment 2 tracked 11 sites for 16 years that received thinning/no pruning, thinning plus pruning (25% of trees), thinning plus pruning (50% of trees), and no thinning/no pruning treatments. We investigated (i) how pruning lift height affects tree form and understory production and (ii) how pruning density affects canopy closure and understory production. In Experiment 1, pruning reduced butt log taper and did not adversely affect diameter or height in either species. Pruning lift was visible in height-to-live crown measurements. Crown recession occurred first in low lift treatments and later in all treatments until crown form was similar after 28–31 years. Epicormic branching rates in Sitka spruce peaked 6–9 years after treatment before falling sharply. Deer forage declined through time and did not differ between lift treatments. In Experiment 2, canopy closure was lower shortly after thinning and pruning, but did not differ from the control after 16 years. Epicormic branching rates were greater shortly after thinning and pruning but did not differ from the control after 16 years. Deer forage declined with canopy closure and thinned and pruned treatments exhibited greater forage than the control. We conclude that pruning can improve log quality for timber applications but does not enhance understory plant biomass and deer forage over thinning treatment alone. [ABSTRACT FROM AUTHOR]

Mosquitoes of the genera Aedes, Anopheles and Culex vector a wide range of pathogens seriously affecting humans and livestock on a global scale. Over-reliance on insecticides and repellents has driven research into alternative, naturally-derived compounds to fulfil the same objectives. Steam distilled extracts of four plants with strong, yet attractive, volatile profiles were initially assessed for repellency in a dual-port olfactometer using Aedes aegypti as the model species. Picea sitchensis was found to be the most repellent, proving comparable to leading products when applied at 100% (p = 1.000). Key components of conifer-derived volatile profiles were then screened via electroantennography before those components eliciting an electrophysiological response were assayed individually in the olfactometer; according to WHO protocol. The most promising 5 were selected for reductive analyses to produce an optimised semiochemical blend. This combination, and a further two variations of the blend, were then progressed to a multi-species analysis using the BG-test whereby bite-attempt frequency on hands was assessed under different repellent treatments; assays were compared between Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus. Efficacy was found against all three species, although it was found that Ae. aegypti was the most susceptible to the repellent, with An. gambiae being the least. Here, a novel, naturally-derived blend is presented with weak spatial repellency, as confirmed in laboratory assays. Further work will be required to assess the full extent of the potential of the products, both in terms of field application and species screening; however, the success of the products developed demonstrate that plant metabolites have great capacity for use in the repellent sector; both to improve upon known compounds and to reduce the usage of toxic products currently on the market. [ABSTRACT FROM AUTHOR]

Red Crossbills (Fringillidae: Loxia curvirostra) are finches specialized to pry open cones and extract seeds of coniferous trees. Within the species, variable bill morphology may provide more efficient foraging on some species of conifers than others. Subgroups also have distinctly different contact calls often given in flight (hereafter, call types). Variable morphology and discrete call types suggest the existence of distinct evolutionary lineages. Because coniferous trees produce seeds on irregular and unpredictable schedules, crossbills wander widely in search of food. The key conifer hypothesis suggests that each call type diverged by specializing on a single conifer species to maximize foraging efficiency, while other hypotheses have emphasized geographic isolation as a driver of lineage divergence. To quantify the degree to which call types occur with specific conifer species, we surveyed Red Crossbills in five ecoregions of western and central Oregon, USA, an area with high conifer diversity. Two of five call types (Types 5 and 10) were encountered in only one ecoregion and associated with their hypothesized key conifers. Three others (Types 2, 3, and 4) were found to wander widely and did not exclusively align geographically with their presumed key conifer species. Whereas types 2 and 3 were sometimes associated with their proposed key conifers, they wandered widely during our 2-year study and occurred with a wide variety of conifers. Type 4 was not significantly associated with its key conifer and also wandered widely during our study. Relationships of call types with key conifers were weaker in the winter and spring, when Types 3 and 4 were frequently encountered in hard-coned pines rather than their soft-coned key conifer species. In our study area, the key conifer hypothesis was strongly supported only for call type 10 as that call type was not encountered away from the coastal range of Sitka Spruce (Picea sitchensis). We found mixed support for the key conifer hypothesis based on our measure of geographic associations of crossbills with a diverse array of coniferous tree species. In most cases we observed, crossbills wandered widely and associated with multiple species of conifers. [ABSTRACT FROM AUTHOR]

Sitka spruce is a widely planted and economically important tree species in the United Kingdom; hence, identifying any future biotic or abiotic threats to its productivity is important. Defoliating insects are widely considered to be major forest disturbance agents, and these can include the sawflies (Symphyta), which are well known to reach high population densities that can cause significant outbreak events, leading to tree mortality or impacts on growth.The aim of the current study was to investigate the abundance and diversity of sawflies within stands of Sitka spruce over an elevation range and to evaluate whether there were any potentially important species present. Experimental plots were established in two commercial forest plantations in mid‐Wales, and the adult sawfly community was assessed over a 3‐year period using yellow pan traps.Sixty species of sawfly were caught over the 3‐year period, which accounted for >11% of all known British sawfly species. Results indicated that there were generally greater abundance and diversity of sawflies at lower elevational plots, where temperatures were higher. The most abundant sawfly species captured in the study was the notable defoliator species, the mountain spruce sawfly (Epicenematus montanus), which was found in particularly high numbers in the low‐elevation plot in Hafren forest. A further seven spruce‐associated sawfly species were also caught across the experimental plots.The study highlighted the presence of a number of notable spruce‐associated sawfly species (E. montanus and Pristiphora spp.), some of which have caused significant defoliation of spruce (Picea) species in Europe. The generally higher abundance of these sawflies at lower elevations indicated that Sitka spruce may potentially become more vulnerable to defoliation events caused by sawfly outbreaks in the future, especially when considering current projected climate change predictions. [ABSTRACT FROM AUTHOR]

Introduced tree species have become increasingly important in the context of the ongoing climate change. This paper focuses on the dendrochronology of the most widespread introduced tree species in the British Isles – Sitka spruce (Picea sitchensis [Bong.] Carr.) – in comparable soil conditions in England, Czechia, and Slovakia. The research aims to evaluate the growth dynamics and the influence of climatic factors on this tree species while comparing it with economically main tree species in Europe – Norway spruce (Picea abies [L.] Karst.). Based on the analysis of 150 increment cores, the radial growth of Sitka spruce was on average 24.2% higher than that of Norway spruce. The highest increments in 52 to 62-year-old stands were achieved in England by both Sitka spruce (8.7 mm) and Norway spruce (7.0 mm). In terms of negative pointer years (NPYs), there was no difference in the number of years with a significantly low increment between the two species at any site. The lowest effect of climatic factors on growth was found in Czechia, while the highest was in England. Higher resistance to climate was found for Sitka compared to Norway spruce. In general, the main limiting factor for the growth was the lack of precipitation in the previous year’s vegetation season, or heavy frost in England. In Central Europe, due to low precipitation, Sitka spruce will not be a substantial introduced tree species in the future, but on suitable sites, it can achieve high production potential and play a significant role for increasing stand diversity in the face of climate change.

The biogenic volatile organic compounds (BVOCs) emitted by Sitka spruce (Picea sitchensis) trees, housed in a plant growth chamber, were characterised by a combination of on-line (time-of-flight chemical ionisation mass spectrometry) and off-line (gas chromatography-mass spectrometry) techniques. In total, 74 BVOCs were identified in the Sitka spruce emissions, 52 of which were oxygenated compounds, with piperitone (C10H16O), an oxygenated monoterpene, being the dominant emission. Other prevalent emissions included isoprene and five monoterpenes (myrcene, β-phellandrene, δ-limonene, α-pinene, and camphene). Temperature, photosynthetic photon flux density (PPFD) and stress were all found to alter the emission profiles, with different BVOCs exhibiting different responses. Three different plant growth cycles were used to identify the emission pathways (pooled or biosynthetic) for each BVOC, through determination of the relationships of the emission flux with temperature and with PPFD. The majority of the BVOCs emitted by Sitka spruce were found to originate from biosynthetic and pooled pathways simultaneously, with those from a stressed tree having a much lower contribution from the biosynthetic pathway than a healthy tree. Standardised emission fluxes (temperature 30 °C and PPFD 1000 µmol m-2 s-1) were calculated for all BVOCs using the appropriate standardisation model (pooled, biosynthetic or combined). Annual emission fluxes for all Stika spruce plantations in Ireland were determined for piperitone (8,200 tonne year-1), isoprene (13,000 tonne year-1) and monoterpenes (1,600 tonne year-1). At the current conditions of the Irish climate the annual BVOC flux for isoprene was found to exceed that for piperitone, although this is expected to change in a warming climate. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to quantify the environmental impacts of Sitka spruce timber products harvested from the forestry sector in Ireland. This data is typically country-specific and is required to accurately quantify the environmental impacts associated with its production to better understand the impacts on the environment. Methods: A representative model utilising the ReCiPe midpoint approach is developed for the forest sector and the production of log products in Ireland from primary data collected from the national forestry agencies, boardmill and sawmills over a 12-month period, where the last two represent 100% and 67% of the national production volume, respectively. The model was analysed using Life Cycle Assessment (LCA) and the resulting environmental impacts of log production are presented for two different boundary conditions, namely 'cradle-to-forest road' and 'cradle-to-factory gate' which considers the transport of the logs for further processing. Results and discussion: The results are presented for the reference functional unit of 1 m3 of Sitka spruce log product but the results are also shown for 1 rotation of 1 ha of forest area, which allows comparisons with existing studies that utilise similar metrics such as a given area of forest. The results show that typically, clearfell operations are the most significant contributor to all impact categories. The contribution of the remaining operations in descending order of magnitude are thinning operations, forest road construction and maintenance, site preparation options, seedling production and finally forest maintenance operations. The extended model ('cradle-to-factory gate' model), which includes transport or delivery, has demonstrated a significant contribution due to transport alone where it was found to be responsible for, on average, 50% of each impact category presented (excluding land occupation) highlighting its significance. Conclusions: The underlying Life Cycle Inventory (LCI) data, which quantifies the total outputs of emissions and substances to air, land and water, is presented. It can be seen that the contribution of different operations varies significantly dependent on the log type which provides important data which can be further incorporated into future studies for downstream products utilised in the construction industry. [ABSTRACT FROM AUTHOR]

Key message: This study compares the measured radial variation in wood stiffness, strength, and density of noble fir, Norway spruce, western hemlock, and western red cedar by developing mixed-effects models for each property using age as the explanatory variable. These models could be used to simulate the effect of rotation length and species choice on sawn wood properties. Context: Timber production in Great Britain relies primarily on Sitka spruce. The use of multiple species is desirable to mitigate against biotic and abiotic risks posed to a single species. When considering alternative species, quantifying and modeling radial variation in wood properties is important to determine the potential for sawn timber production at a given rotation length. Aims: To build empirical models for the radial variation in wood properties that can account for species. Methods: Clear-wood samples were produced along radial transects in trees from four conifer species: Abies procera Rehder, Picea abies (L.) Karst, Tsuga heterophylla (Raf.) Sarg., Thuja plicata Donn. ex D.Don. Modulus of Elasticity, Modulus of Rupture, and density were measured on each species according to established standards. Mixed-effects models were built using ring numbers from the pith and species as explanatory variables. Results: The same model forms could be used across the four species. Nonlinear models were developed for the Modulus of Elasticity and density. For the Modulus of Rupture, a linear model was most appropriate. The effect of species in the models was significant. Conclusion: At similar rotation lengths, noble fir, Norway spruce, and western hemlock can produce timber with comparable properties to Sitka spruce. Overall, western red cedar would have worse properties for structural use. [ABSTRACT FROM AUTHOR]

Many quantitative genetic models assume that all genetic variation is additive because of a lack of data with sufficient structure and quality to determine the relative contribution of additive and non-additive variation. Here the fractions of additive (fa) and non-additive (fd) genetic variation were estimated in Sitka spruce for height, bud burst and pilodyn penetration depth. Approximately 1500 offspring were produced in each of three sib families and clonally replicated across three geographically diverse sites. Genotypes from 1525 offspring from all three families were obtained by RADseq, followed by imputation using 1630 loci segregating in all families and mapped using the newly developed linkage map of Sitka spruce. The analyses employed a new approach for estimating fa and fd, which combined all available genotypic and phenotypic data with spatial modelling for each trait and site. The consensus estimate for fa increased with age for height from 0.58 at 2 years to 0.75 at 11 years, with only small overlap in 95% support intervals (I95). The estimated fa for bud burst was 0.83 (I95=[0.78, 0.90]) and 0.84 (I95=[0.77, 0.92]) for pilodyn depth. Overall, there was no evidence of family heterogeneity for height or bud burst, or site heterogeneity for pilodyn depth, and no evidence of inbreeding depression associated with genomic homozygosity, expected if dominance variance was the major component of non-additive variance. The results offer no support for the development of sublines for crossing within the species. The models give new opportunities to assess more accurately the scale of non-additive variation. [ABSTRACT FROM AUTHOR]

The UK proposes additional bioenergy plantations and afforestation as part of measures to meet net-zero greenhouse gas emissions, but species and locations are not yet decided. Different tree species emit varying amounts of isoprene and monoterpene volatile organic compounds that are precursors to ozone and secondary organic aerosol (SOA) formation, the latter of which is a component of PM 2.5. The forest canopy also acts as a depositional sink for air pollutants. All these processes are meteorologically influenced. We present here a first step in coupling information on tree species planting suitability and other planting constraints with data on UK-specific BVOC emission rates and tree canopy data to simulate, via the WRF-EMEP4UK high spatial-resolution atmospheric chemistry transport model, the impact on UK air quality of four potential scenarios. Our "maximum planting" scenarios are based on planting areas where yields are predicted to be ≥ 50 % of the maximum from the Ecological Site Classification decision support system (ESC DSS) for Eucalyptus gunnii, hybrid aspen (Populus tremula), Italian alder (Alnus cordata) and Sitka spruce (Picea sitchensis). The additional areas of forest in our scenarios are 2.0 to 2.7 times the current suggestions for new bioenergy and afforestation land cover in the UK. Our planting scenarios increase UK annual mean surface ozone concentrations by 1.0 ppb or 3 % relative to the baseline land cover for the highest BVOC-emitting species (e.g. E. gunnii). Increases in ozone reach 2 ppb in summer when BVOC emissions are greatest. In contrast, all the additional planting scenarios lead to reductions in UK annual mean PM 2.5 – ranging from - 0.2 µg m -3 (- 3 %) for Sitka spruce to - 0.5 µg m -3 (- 7 %) for aspen – revealing that PM 2.5 deposition to the additional forest canopy area more than offsets additional SOA formation. Relative decreases in annual mean PM 2.5 are greater than the relative increases in annual mean ozone. Reductions in PM 2.5 are least in summer, coinciding with the period of maximum monoterpene emissions. Although only a first step in evaluating the impact of increased forest plantation on UK air quality, our study demonstrates the need for locally relevant data on land cover suitability, emissions and meteorology in model simulations. [ABSTRACT FROM AUTHOR]

Bark-feeding and wood-boring insect pests can have significant negative impacts on conifers and wood production. The damage they cause is expected to increase in the future due to climate change and the growth of international trade. This study employed DNA barcoding of beetle juveniles (Coleoptera) sampled from standing trap trees and cut log piles at regular intervals over a 2-yr period to monitor the beetle community dynamics and associated environmental factors. Tree species was found to have a major influence on beetle communities, most strikingly at the start of early decay stages. Lower species diversity was reported from standing trap tree samples compared to log pile samples, likely due to higher residual defences in dying and recently dead trees. While the species identified from standing trap trees are more likely to be a threat to the forestry sector, the species found in the log piles are more likely to be beneficial due to their high abundance and their ability to compete with pests for breeding substrate. The analysis of beetles collected inside trees revealed additional information on ontogenetic niches and host preferences beyond that acquired solely from flight interception trap data. Our results offer insights on community composition and dynamics of bark-feeding and wood-boring insect species in Welsh conifer forests and provide resources for monitoring and management of potential pest species. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is a major pathophysiological problem defined by severe inflammation and acute disease with substantial morbidity and death. It is known that lipopolysaccharide (LPS) induces ALI by causing oxidative stress and inflammation. The goal of this study was to investigate the protective effect of astringin on LPS-induced ALI and probable pathways. Astringin is a stilbenoid, the 3-β-D-glucoside of piceatannol, mainly found in the bark of Picea sitchensis. The findings showed that astringin prevented LPS-induced cellular damage by reducing the generation of oxidative stress in LPS-stimulated A549 lung epithelial cells. Furthermore, astringin extensively decreased the production of inflammatory factors such as TNF-α, IL-1β, and IL-6. In addition, the western blot results revealed that the ability of astringin to reduce oxidative stress and the generation of inflammatory cytokines by inhibiting the ROS-mediated PI3K/AKT/NF-κB pathway could be the reason for its protective effect against LPS-induced ALI. Overall, the results suggest that astringin could be a possible inhibitor of ALI triggered by LPS for pediatric lung injury. [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]

Image courtesy of Justin G. A. Whitehill, North Carolina State University, USA. B Cover Legend b Sitka spruce stone cell cluster (green) contrasted against polyphenolic cells (magenta) and primary walls (blue). (Whitehill I et al i ., pp. 2138-2152). [Extracted from the article]

Afforestation and reforestation to meet 'Net Zero' emissions targets are considered a necessary policy by many countries. Their potential benefits are usually assessed through forest carbon and growth models. The implementation of vegetation demography gives scope to represent forest management and other size-dependent processes within land surface models (LSMs). In this paper, we evaluate the impact of including management within an LSM that represents demography, using both in-situ and reanalysis climate drivers at a mature, upland Sitka spruce plantation in Northumberland, UK. We compare historical simulations with fixed and variable CO2 concentrations, and with and without tree thinning implemented. Simulations are evaluated against the observed vegetation structure and carbon fluxes. Including thinning and the impact of increasing CO2 concentration ('CO2 fertilisation') gave more realistic estimates of stand-structure and physical characteristics. Historical CO2 fertilisation had a noticeable effect on the Gross Primary Productivity seasonal–diurnal cycle and contributed to approximately 7% higher stand biomass by 2018. The net effect of both processes resulted in a decrease of tree density and biomass, but an increase in tree height and leaf area index. [ABSTRACT FROM AUTHOR]

In recent years, the use of hybrid composites, in which natural fibers combine with synthetic fibers, in place of composite structures consisting only of synthetic fibers has become increasingly popular due to growing environmental concerns and the need to develop sustainable, more lightweight, recyclable materials required for engineering applications. In this regard, the present paper is an attempt to show the usage of sitka spruce as an alternative to synthetic E-glass fiber and natural flax fiber in design of interply hybrid composite structures in terms of fundamental frequency, buckling resistance and weight. The single-objective and multi-objective approaches are considered to acquire optimum design for non-hybrid and hybrid structures. The modified versions of the optimization methods Differential Evolution (MDE), Nelder Mead (MNM) and Simulated Annealing (MSA) algorithms are considered to solve problems. The results show that the optimum design of the hybrid graphite/epoxy-sitka spruce laminated plate to obtain the structure having a more lightweight (e.g., 53%), higher frequency (e.g., 65%) and buckling resistance (e.g., 90%) was computed and compared with those of the hybrid graphite-flax/epoxy, neat sitka spruce, neat flax/epoxy and neat glass/epoxy laminated composite plates. [ABSTRACT FROM AUTHOR]

This article seeks to animate historical resource geographies by uncovering unforeseen material lineages and foregrounding the lived experiences of otherwise unremembered resource workers. We revisit research on the historical resource geographies of the guitar, adapting what McGeachan (2018) calls 'the trace' to connect material archival fragments with visceral, ethnographic encounters in multiple sites, in the present. Unlike classical instruments with extensive documentation, the guitar's historical resource geographies remain opaque, being mass manufactured since the 1800s from commercial timbers with vague provenance. Here, we trace one guitar wood, Sitka spruce (Picea sitchensis) — the most common for soundboards — from a chance discovery in a Pennsylvania factory archive to the Pacific Northwest to confirm colonial, industrial, and military origins. Sitka's material traces also facilitated impromptu ethnographic encounters, including opportunities to meet surviving ex-workers in Hoquiam, Washington state, who, many decades ago, milled wood for musical instruments. Following the trace in multiple, unexpected directions enabled us to sense the working lives of ex-timber workers while confronting environmental legacies, bearing witness to the people, places, and trees behind the guitar. Our research validates feminist and anticolonial methodological approaches that, while tracing material fragments in time and space, encounter the world viscerally. Resulting empirical explanations are richer, open to emotional ambivalence and ongoing dialogue. • Historical resource geographies are animated through material traces. • Archival and ethnographic fragments invite nonlinear research trajectories. • Traces the guitar industry's past exploitation of Sitka spruce. • Researchers 'bear witness' to diverse experiences and emotions. • Everyday cultures in past workplaces are sensed: hidden lives and labour. [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]

Long-read sequencing technologies have improved significantly since their emergence. Their read lengths, potentially spanning entire transcripts, is advantageous for reconstructing transcriptomes. Existing long-read transcriptome assembly methods are primarily reference-based and to date, there is little focus on reference-free transcriptome assembly. We introduce "RNA-Bloom2 [https://github.com/bcgsc/RNA-Bloom]", a reference-free assembly method for long-read transcriptome sequencing data. Using simulated datasets and spike-in control data, we show that the transcriptome assembly quality of RNA-Bloom2 is competitive to those of reference-based methods. Furthermore, we find that RNA-Bloom2 requires 27.0 to 80.6% of the peak memory and 3.6 to 10.8% of the total wall-clock runtime of a competing reference-free method. Finally, we showcase RNA-Bloom2 in assembling a transcriptome sample of Picea sitchensis (Sitka spruce). Since our method does not rely on a reference, it further sets the groundwork for large-scale comparative transcriptomics where high-quality draft genome assemblies are not readily available. Most existing long-read transcriptome assembly methods rely on reference genomes and transcript annotations, while reference-free methods remain scarce. Here, Nip et al. introduce RNA-Bloom2, a reference-free method that requires substantially less memory and runtime than other reference-free methods. [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]

Sitka spruce (Picea sitchensis) needles contain a variety of bioactive compounds including phenolic compounds and flavonoids, many of which have been used in the cosmetic, pharmaceutical, and food industries. This study aimed to investigate the effects of novel extraction techniques, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and simultaneous ultrasound-microwave-assisted extraction (UMAE) on the recovery of phenolic, flavonoids and associated antioxidant and anti-cancer properties from Sitka spruce (Picea sitchensis) needles. The ferric reducing antioxidant power (FRAP) assay was used to evaluate the antioxidant capacity, and the Alamar Blue assay using the human brain glioblastoma cancer cellline (U-251 MG) was used to evaluate the cytotoxicity activity. Results showed that US-probe accomplished the highest recovery of phenolic and flavonoids at 38 W cm-2 for 10 min (106.3 f 2.5 mg GAE g-1 DW and 63.2 i 3.8 mg QE g-1 DW, respectively). Hence, the highest cytotoxicity activity of IC5O (0.0114% w/v) was achieved by US-probe at 19 W cm-2 for 10 min. However, the antioxidant capacity of (2591.3 f 92.5 mM TE g-1 DUO was achieved under UMAE at ultrasound intensity of 38 W cm-2, microwave power of 302.4 W for 10 min. This study emphasised the potential application of UAE and MAE in the extraction of bioactive as an environmentally friendly method to be used in the valorisation of by-products in food and agro-industries. This supports the use of renewable natural resources in an efficient way to produce high-value compounds therefore it is in line with the new era of bioeconomy and its new biorefinery concepts. [ABSTRACT FROM AUTHOR]

To investigate how source and processing control the composition of "terrestrial" dissolved organic matter (DOM), we combine soil and tree leachates, tree DOM, laboratory bioincubations, and ultrahigh resolution Fourier-transform ion cyclotron resonance mass spectrometry in three common landscape types (upland forest, forested wetland, and poor fen) of Southeast Alaska's temperate rainforest. Tree (Tsuga heterophylla and Picea sitchensis) needles and bark and soil layers from each site were leached, and tree stemflow and throughfall collected to examine DOM sources. Dissolved organic carbon concentrations were as high as 167 mg CL−1 for tree DOM, suggesting tree DOM fluxes may be substantial given the hypermaritime climate of the region. Condensed aromatics contributed as much as 38% relative abundance of spruce and hemlock bark leachates suggesting coniferous trees are potential sources of condensed aromatics to surface waters. Soil leachates showed soil wetness dictates DOM composition and processing, with wetland soils producing more aromatic formulae and allowing the preservation of traditionally biolabile, aliphatic formulae. Biodegradation impacted soil and tree DOM differently, and though the majority of source-specific marker formulae were consumed for all sources, some marker formulae persisted. Tree DOM was highly biolabile (> 50%) and showed compositional convergence where processing homogenized DOM from different tree sources. In contrast, wetland and upland soil leachate DOM composition diverged and processing diversified DOM from different soil sources during bioincubations. Increasing precipitation intensity predicted with climate change in Southeast Alaska will increase tree leaching and soil DOM flushing, tightening linkages between terrestrial sources and DOM export to the coastal ocean. [ABSTRACT FROM AUTHOR]