Cambial Age Research Articles

Wood density and chemical composition variation of Eucalyptus urophylla clone in different environments

Abstract Variability in Eucalyptus wood density and chemical properties is crucial to understanding important factors for the forest-based industry, such as sampling methods and wood suitability as raw material. This study aimed to evaluate the basic density and chemical composition of the radial positions of young wood from the Eucalyptus urophylla clone grown under different precipitation levels. Trees from E. urophylla clonal plantations were collected in Inhambupe, Jandaíra and Itanagra, Bahia State, Brazil. Trees’ basic density and chemical composition (total extractive, lignin, hemicelluloses and α-cellulose) were determined based on the basal log of each tree, at four radial positions (1, 2, 3 and 4). It was found that the basic density and α-cellulose of wood are influenced by the cambial age and the site rainfall. There was greater increase in sections close to the bark (positions 1 and 4) and in more humid environments (sites Itanagra and Jandaríra). This finding highlights the association between wood basic density and chemical composition, mainly in the holocellulose content.

Tip-to-base conduit widening remains consistent across cambial age and climates in Fagus sylvatica L.

Water transport, mechanical support and storage are the vital functions provided by the xylem. These functions are carried out by different cells, exhibiting significant anatomical variation not only within species but also within individual trees. In this study, we used a comprehensive dataset to investigate the consistency of predicted hydraulic vessel diameter widening values in relation to the distance from the tree apex, represented by the relationship Dh ∝ Lβ (where Dh is the hydraulic vessel diameter, L the distance from the stem apex and β the scaling exponent). Our analysis involved 10 Fagus sylvatica L. trees sampled at two distinct sites in the Italian Apennines. Our results strongly emphasize that vessel diameter follows a predictable pattern with the distance from the stem apex and β~0.20 remains consistent across cambial age and climates. This finding supports the hypothesis that trees do not alter their axial configuration represented by scaling of vessel diameter to compensate for hydraulic limitations imposed by tree height during growth. The study further indicates that within-tree variability significantly contributes to the overall variance of the vessel diameter-stem length exponent. Understanding the factors that contribute to the intraindividual variability in the widening exponent is essential, particularly in relation to interspecific responses and adaptations to drought stress.

A python package implementing Direct Reconstruction Technique (DIRECT) for dendroclimatological studies

The DIrect REConstruction Technique (DIRECT) is a dendroclimatological method that constructs a climatic response surface to account for changes of climatic response with tree age. This surface is then used as a transfer function for climatic reconstructions. Unlike widely-used standardization methods such as the traditional curve-fitting approach, the regional curve standardization, and their signal-free modifications that perform detrending explicitly, DIRECT accounts for age-size related trend in tree-ring measurements by construction of the response surface dependent on two variables: tree-ring parameter (width, blue intensity etc.) and cambial age. The method is capable of taking into account nonlinear climatic response of trees and differing response of younger and older trees. Here we describe an application of the newly developed open-source Python package that implements DIRECT (https://github.com/Gr1Lo/direct) to one real and one theoretical dataset. The package consists of functions for reading the initial data, constructing a response surface, and for reconstructing climate variables via this surface. The functions for visual assessment of the initial data and for the estimation and selection of parameters for constructing the response surface are also presented. Also here we provide a comparison of the DIRECT method with traditional standardization-reconstruction routines.

Radial distribution of heartwood extractives in second-growth western redcedar

Western redcedar has high economic value and has been traditionally used for cultural purposes by Indigenous communities. Second-growth redcedar is potentially growing faster due to lower planting densities, fertilization, and tree breeding. Little quantitative information is available about the impact of management practices on wood quality, particularly heartwood extractives. This study evaluated the effects of growth rate and site on heartwood extractives at two locations aged 70–90 years in British Columbia, Canada. A three-parameter sigmoid model was fit to the data using nonlinear mixed effects to analyze the relationship between heartwood extractives relative to cambial age, growth rate, and sampling site. The southern site had significantly higher cumulative extractive concentrations, while all extractive concentrations increased faster. This study shows that smaller trees will reach their peak concentrations earlier than larger trees. Results show that faster growth through active management of western redcedar may lead to increased and more uniformly distributed content of heartwood extractives.

Lower wood stiffness in old-growth than in post-cut and post-fire stands indicates forest structure is a key driver of wood properties in black spruce

Forest fires and logging drive the structure of boreal forest landscapes. According to recent studies, stand origin is a key driver of the variation in wood properties in black spruce (Picea mariana (Mill.) BSP.), although the underlying mechanisms remain to be elucidated. By comparing post-cut, post-fire and old-growth forests, this study aimed to better distinguish the effects of stand structure from those of the seed or layer origin of the trees on wood properties. We conducted comparative analyses based on ecological characteristics of the sites and static bending tests of small, defect-free wood specimens. Black spruce stands with a regular structure established after logging or fire exhibited higher stiffness at a given cambial age than old-growth forests with irregular structures, as well as lower wood density in the first 40 rings near the pith. However, the bending strength was comparable in all three types of forests studied. Differences in wood stiffness among stand types appeared to be driven more by stand structure than by the seed or layer origin of the stems.

Inter- and intra-growth ring variations of wood carbon fractions in Pinus tabuliformis

Abstract Carbon fraction (CF) of trees is essential for quantifying forest carbon (C) stocks. Considerable attention has been paid to CF variations at various levels with the exception of inter- and intra-growth rings. Herein, the inter- and intra-growth ring variation of CF in Pinus tabuliformis was investigated. Elemental analysis was performed to obtain CF values of the earlywood and latewood in each growth ring of the xylem. Patterns of CF variation at the growth ring level were evaluated using mixed-effect models. The results showed that latewood CF, 50.6 %, was significantly higher than earlywood CF, 49.9 % (p < 0.01). In particular, inter-growth ring variations of CF differed between heartwood and sapwood, as well as between juvenile wood and mature wood. CF values decreased nonlinearly with cambium age toward the heartwood or juvenile wood, with estimated least-squares means of 50.4 % and 51.8 %, respectively. While CF values were almost unaltered in sapwood, and slightly decreased in mature wood, with estimated least-squares means of 50.0 % and 50.2 %, respectively. It indicates that patterns of CF variation between juvenile wood and mature wood are important to estimate the C stock of P. tabuliformis. This research provides insights into C uptake dynamics to support forest management and wood utilization.

Environmental and ontogeny effects in wood fiber properties of Pterocarpus ericaneus (Poir.)

ABSTRACT The present study examined the wood properties of Pterocarpus erinaceus, a species found in West Africa's Guineo-Sudanian and Sudano-Sahelian zones. The primarily focus was on wood fiber properties, which serve as indicators of cambial growth and the transition between juvenile and mature wood. The aim was to analyze the factors contributing to the variability of the wood fiber properties. Specifically, it examined the effect of cambial age and ecological factors on fiber properties and analyzed how the fiber properties influence density and dimensional characteristics of the wood. Measurements of fiber properties were obtained from 451 specimens collected in the Guinean, Sudanian, and Sahelian zones in Burkina Faso, Niger, and Togo. The results indicate significant variations in average fiber parameters among the three climatic zones. This variability leads to an increase in the length, width, and thickness of the fibers along the north–south decreasing rainfall gradient. However, no noteworthy correlations were observed between cambial age and fiber properties, posing challenges in distinguishing between juvenile and adult wood. In terms of correlation, the analysis shows that fiber length has no effect on physical properties, but fiber width significantly influences basic density, wood shrinkage, and the fiber saturation point (FSP).

Cambial Age Influences PCD Gene Expression during Xylem Development and Heartwood Formation

Heartwood formation is an important ontogenetic stage in Scots pine (Pinus sylvestris L.). The amount of heartwood determines the proportion of functionally active sapwood in the total trunk biomass as well as the quality of wood. The key criterion for heartwood formation is the death of xylem ray parenchyma cells. Previously, models that described the patterns of heartwood formation, depending on the cambial age, were derived from Scots pine trees of different ages. The cambial age is the number of annual xylem layers at the core sampling site at a certain trunk height. We studied the features of the occurrence of programmed cell death (PCD) processes during the xylem differentiation and heartwood formation of 80-year-old Scots pine trees, depending on the cambial age, under the lingonberry pine forest conditions in the transition area of the northern taiga subzone and tundra. We have shown that the distance from the cambial zone to the heartwood boundary does not change significantly with stem height. As the cambial age increases, the lifespan of the formed xylem ray parenchyma cells increases and the activity of PCD genes decreases during the formation of both (1) xylem (in the outer layers of sapwood) and (2) heartwood (in the inner layers of sapwood and transition zone). We hypothesized that the decisive factor in the PCD initiation during heartwood formation is the distance of the xylem ray parenchyma cells from the cambial zone. The younger cambium forms wider annual increments, and therefore the xylem ray parenchyma cells in these parts of the trunk reach the distance from the cambial zone earlier, which is necessary for PCD initiation.

European larch sapwood: A model for predicting the cambial age and for a more accurate dating

European larch (Larix decidua Mill.) holds significant importance as a forest tree species throughout the Alps and in certain regions of central Europe. Its extensive use as construction timber has made it a subject of substantial interest in dendroarchaeological studies aimed at understanding the long-term interactions between human societies and forests. Precise dating of felling phases, accurate estimation of the age of harvested wood, and information on the geographical origin of wood play a crucial role when it comes to characterize these interactions. In this study, we compiled a large dataset of L. decidua samples from across the European Alps to provide a robust statistical model that predicts the cambial age of L. decidua trees based on the number of heartwood rings. By extension, this model can be used to estimate the number of sapwood rings so as to approximate the felling date and to more precise date archaeological larch timber. The model requires almost complete heartwood sequences (<5 missing rings) to achieve accurate estimations. Our results also evidence that the ratio between the number of sapwood and heartwood rings varies across the Alps. At the same time, the indicator developed in this work is not suitable for a determination of wood origin, raising doubts about the effectiveness of attempts aimed at dendroprovenancing L. decidua based on sapwood.

Age of heartwood initiation in trunks of young Pinus sylvestris L. trees in the taiga zone

Summary This work is part of a project investigating the heartwood formation process in Scots pine. Despite the economic and ecological importance of pine heartwood (HW), the process of its formation in many respects remains poorly understood. Scientists believe that HW formation in Scots pine begins at 9–20 years, however, systematic studies of HW initiation age in this species have not previously been conducted. Samples were collected from 105 P. sylvestris trees aged 10 to 25 years, growing in the middle and northern taiga subzones, as well as on the border of the northern taiga subzone with the tundra. Samples were taken at the trunk base according to a single technique and processed using two biochemical (peroxidase activity, pinosylvin presence) and two anatomical markers (presence of extractives on the tracheid pit membranes, nuclei disappearance) characterizing different events during HW formation. Biochemical markers showed an overestimation in the number of HW annual rings compared with HW determination based on anatomical criteria by 1–3 years, on average. Attempts to detect peroxidase activity showed a negative result in the inner sapwood annual ring, while detectable pinosylvin accumulation occurred in the transition zone (TZ). We have detected for the first time true HW (without living cells) in Scots pine samples with a cambial age (CA) of 15–17 years. The number of growth rings in TZ and HW in young trees depended on growth conditions. These results are important for understanding the mechanisms of HW formation and developing realistic models of this process, including changing climate conditions.

Development of Spatiotemporal Whole-Stem Models for Estimating End-Product-Based Fibre Attribute Determinates for Jack Pine and Red Pine

The objective of this study was to develop spatiotemporal whole-stem wood quality prediction models for a suite of end-product-based fibre attribute determinates for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Aiton): specifically, for wood density (Wd), microfibril angle (Ma), modulus of elasticity (Me), fibre coarseness (Co), tracheid wall thickness (Wt), tracheid radial diameter (Dr), tracheid tangential diameter (Dt), and specific surface area (Sa). Procedurally, these attributes were determined for each annual ring within pith-to-bark xylem sequences extracted from 610 jack pine and 223 red pine cross-sectional disks positioned throughout the main stem of 61 jack pine and 54 red pine sample trees growing within even-aged monospecific stands in central Canada. Deploying a block cross-validation-like approach in order to reduce serial data dependency and enable predictive performance assessments, species-specific calibration and validation data subsets consisting of cumulative moving average values were systematically generated from the 27,820 jack pine and 11,291 red pine attribute-specific annual ring values. Graphical, correlation, regression and validation analyses were used to specify, parameterize and assess the predictive performance of tertiary-level (ring-disk-tree) hierarchical mixed-effects whole-stem equations for each attribute by species. As a result, the jack pine equations explained 46, 66, 74, 63, 59, 72, 42 and 48% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. The red pine equations explained slightly higher levels of variation except for Me: 50, 71, 31, 83, 72, 78, 56 and 71% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. Graphical assessments and statistical metrics related to attribute and species-specific residual error patterns and goodness-of-fit, lack-of-fit and predictive error metrics, revealed an absence of systematic bias, misspecification or aberrant predictive performance. Consequently, the resultant parameterized models were acknowledged as acceptable functional descriptors of the intrinsic spatiotemporal cumulative developmental patterns of the studied end-product fibre attribute determinates, for these two pine species. Although predicted development patterns were similar between the species with the greatest degree of nonlinearity occurring before a cambial age of approximately 30 years, irrespective of attribute, jack pine exhibited a greater degree of nonlinearity in the Wd and Dt developmental trajectories, whereas red pine exhibited a greater degree of nonlinearity in the Ma, Me, Co, Wt, Dr and Sa developmental trajectories. Potential biomechanical linkages underlying the observed attribute distribution patterns, as well as the potential utility of the models in forest management, are also discussed.

Thinning effectively mitigates the decline of aging Mongolian pine plantations by alleviating drought stress and enhancing plant carbon balance

Intensifying drought around the globe poses strong challenges to the growth and survival of trees, emphasizing the urgency of understanding the physiological mechanisms of drought-induced tree decline and mortality and the necessity of using silvicultural approaches to mitigate drought effects on tree growth. We experimentally explored whether thinning enhances tree growth vigor and drought resilience in early aging Mongolian pine (Pinus sylvestris var. mongolica Litv.) plantations in a water-limited area of Northeast China using dendrochronological methods. Meanwhile, we compared plant hydraulic traits, water relations, and non-structural carbohydrate concentrations between trees growing in the thinned and un-thinned stands with the aim of unraveling the physiological mechanisms underlying the density effects on tree growth performance. The results showed that basal area increments of Mongolian pine trees in the high-density plantations started to decline continuously at tree cambium age of around 15 years over about a decade, while thinning effectively reversed their growth decline. Trees in thinned stands exhibited significantly higher predawn leaf water potentials, higher stem hydraulic conductivities, and larger carbon reserves than trees in un-thinned stands. Although trees growing in high-density stands maintained as low risks of xylem hydraulic dysfunction as trees growing in low-density stands, that was at the cost of substantially reducing tree crown size through branch mortality that unavoidably undermined their carbon balance at the whole-plant level. Consistently, trees growing in the thinned low-density stands showed significantly higher levels of non-structural carbohydrate reserve in stems and enhanced growth resilience to extreme drought than trees growing in the high-density reference stands. Our results suggest that thinning can effectively enhance xylem hydraulic transport efficiency and reduce the risk of carbon imbalance by increasing soil water availability and hence mitigates the early aging of Mongolian pine plantations in water-limited environments.

The influence of age on the timber properties and grading of Scots pine and larch in Ireland

Abstract Scots pine (Pinus sylvestris L.) and larch (Larix spp.) are two species that could contribute to diversifying Ireland’s timber supply. However, there is little knowledge about their properties as well as their variation with age. The aim of this study is to investigate the structural properties (modulus of elasticity, strength and density) of Irish-grown Scots pine and larch and the effect of cambial age on timber grading. Structural-sized pieces were used for this purpose, and the timber properties, knots and ring width were measured on 158 and 250 pieces of Scots pine and larch, respectively. Characteristic values of the properties and indicative yields for different strength classes were calculated. The age effect was assessed using an empirical approach, and a novel modelling approach that disaggregates the timber properties at the annual growth ring level. Yields above 90 per cent of C20 were achieved for Scots pine, whereas larch achieved a 100 per cent yield of C24 strength class. The effect of cambial age in the grading properties indicated that older boards increased the characteristic values of a timber population. In Scots pine, the empirical approach showed that the yields increased by up to 26 per cent when using pieces up to 50 years old compared with pieces up to 30 years old. In larch, the use of pieces up to 40 years old increased the yields by up to 16 per cent compared with using pieces up to 30 years old. The results of the modelling approach were consistent with the values obtained in the empirical analysis and can help to make informed decisions regarding rotation lengths for the production of structural timber. Our results found that cambial ages of 40 years in Scots pine produce high yields of structural timber, whereas 30 years are enough for larch.

Radial growth rate does not affect radial variation of latewood tracheid length in aged trees of Thujopsis dolabrata var. hondae

Summary Tracheid length is lowest at the pith and then it increases rapidly as cambial age increases up until it reaches an asymptote value in what is known as ‘Sanio’s first law’. However, it is still unclear the effect of radial growth rate on latewood tracheid length and the effect of radial variation pattern of latewood tracheid length on the boundary position between juvenile and mature wood in aged trees. Radial variation modeling was applied to annual ring width and latewood tracheid length in aged trees (79–238 years old) of Thujopsis dolabrata var. hondae grown in natural forests and a plantation in Shimokita Peninsula, Aomori, Japan. In addition, the effect of differences in radial variation patterns of latewood tracheid length on the boundary age between juvenile and mature wood was evaluated. Cambial age showing the maximum values of current annual increment and mean annual increment was 42–121 and 65–189 years for natural forests and 30–33 and 46–52 years for the plantation, respectively. A mixed-effects model based on a logarithmic function with an explanatory variable of only cambial age, and random intercepts of stand and individual tree, was selected as the one best explaining the radial variation of latewood tracheid length. The estimated boundary cambial age was approximately 20 years in all trees regardless of radial growth rate. We concluded that (1) the regularity of radial variation in tracheid known as ‘Sanio’s first law’ can be adapted to at least about 250 annual rings from the pith in T. dolabrata trees, (2) the boundary cambial age is similar to that in younger trees, and (3) the effect of radial growth rate on latewood tracheid length is minimal in T. dolabrata.

Resin tapping influence on maritime pine growth depends on tree age and stand characteristics

Resin is a renewable forest resource that can increase the economic value of some forests in rural areas. Resin production is associated with climatic conditions. However, its impact on trees’ growth remains unclear. Here, we studied radial growth in six Portuguese Pinus pinaster forests that had been resin tapped for 5–7 years along a latitudinal and climatic gradient to understand whether resin tapping affects tree growth, and how it is affected by climate, stand and tree traits. Tree-ring width (TRW) on tapped and untapped trunk sides was compared before and during the tapping period. Tree-ring width decreased in the three youngest populations (< 30 years), with no changes in older populations (> 40 years), while TRW increased after resin harvesting began in the oldest stand (> 55 years). Annual resin-tapping impact (RTI), calculated as the ratio between TRW during tapping years and the 5-year average TRW before tapping, was below and above 1 in the younger and older stands, respectively. Among stand characteristics and across sites, RTI was negatively correlated with tree competition and positively correlated with TRW, cambial age, and tree height. Climatic conditions had a minor role on tree growth response to resin tapping. Our main conclusion is that the effect of resin extraction on growth is age-dependent. Our results encourage the co-production of resin and wood on maritime pine stands over 40 years old where resin extraction impact on growth is negligible.

Determination of ring-level dynamic modulus of elasticity in loblolly pine from measurements of ultrasonic velocity and specific gravity

Abstract Wood stiffness (modulus of elasticity, MOE) is an important property for conifer wood, with the variability in MOE largely being a function of both the specific gravity (SG) (wood density) and the angle of the microfibrils within the S2 layer of longitudinal tracheids. Rapid analysis techniques can be used together to quantify MOE; while SG can be determined with relative ease, this is not the case for microfibril angle, requiring expensive X-ray diffraction equipment. An alternative to microfibril angle is to measure longitudinal acoustic velocity. The objective of this study was to measure and then model the within tree variation in dynamic MOE (MOEdyn) by developing the methodology to measure ultrasonic velocity (USV) in radial samples from pith to bark using ultrasonic frequencies (&amp;gt;20 kHz). A total of 419 pith-to-bark radial strips, collected from multiple height levels in 92 loblolly pine (Pinus taeda) trees, were processed to obtain matching SG (2mm longitudinal) and USV (8.2-mm longitudinal) samples. Ring-by-ring SG was measured using X-ray densitometry and time-of-flight USV was measured at a 10-mm radial resolution from pith to bark. A subset of samples was sent to SilviScan to determine microfibril angle using X-ray diffraction. The relationship between microfibril angle and USV was strong (R2 = 0.91, RMSE = 2.6°). Nonlinear mixed-effects models were then developed to predict radial variation in SG, USV and MOEdyn. Fixed effects for the models, which included cambial age and height of disk within tree, had pseudo R2 values of 0.67 for SG (RMSE = 0.051), 0.71 for USV (RMSE = 316 m/s) and 0.69 for MOEdyn (RMSE = 1.9 GPa). When combined with SG measurements from X-ray densitometry, USV measurements from pith to bark are a powerful tool for assessing variability in wood stiffness.

Identification and Expression Profile of CLE41/44-PXY-WOX Genes in Adult Trees Pinus sylvestris L. Trunk Tissues during Cambial Activity

WUSCHEL (WUS)-related homeobox (WOX) protein family members play important roles in the maintenance and proliferation of the stem cells in the cambium, the lateral meristem that forms all the wood structural elements. Most studies have examined the function of these genes in angiosperms, and very little was known about coniferous trees. Pine is one of the most critical forest-forming conifers globally, and in this research, we studied the distribution of WOX4, WOX13, and WOXG genes expression in Pinus sylvestris L. trunk tissues. Further, we considered the role of TDIF(CLE41/44)/TDR(PXY) signaling in regulating Scots pine cambial activity. The distribution of CLE41/44-PXY-WOXs gene expression in Scots pine trunk tissues was studied: (1) depending on the stage of ontogenesis (the first group of objects); and (2) depending on the stage of cambial growth (the second group of objects). The first group of objects is lingonberry pine forests of different ages (30-, 80-, and 180-year-old stands) in the middle taiga subzone. At the time of selection, all the trees of the studied groups were at the same seasonal stage of development: the formation of late phloem and early xylem was occurring in the trunk. The second group of objects is 40-year-old pine trees that were selected growing in the forest seed orchard. We took the trunk tissue samples on 27 May 2022, 21 June 2022, and 21 July 2022. We have indicated the spatial separation expressed of PsCLE41/44 and PsPXY in pine trunk tissues. PsCLE41/44 was differentially expressed in Fraction 1, including phloem cells and cambial zone. Maximum expression of the PsPXY gene occurred in Fraction 2, including differentiating xylem cells. The maximum expression of the PsCLE41/44 gene occurred on 27 May, when the number of cells in the cambial zone was the highest, and then it decreased to almost zero. The PsPXY gene transcript level increased from May to the end of July. We found that the highest transcript level of the PsWOX4 gene was during the period of active cell proliferation in the cambial zone, and also in the trees with the cambial age 63 years, which were characterized by the largest number of cell layers in the cambial zone. In this study, we have examined the expression profiles of genes belonging to the ancient clade (PsWOXG and PsWOX13) in stem tissues in Scots pine for the first time. We found that, in contrast to PsWOX4 (high expression that was observed during the period of active formation of early tracheids), the expression of genes of the ancient clade of the WOX genes was observed during the period of decreased cambial activity in the second half of the growing season. We found that PsWOX13 expression was shifted to Fraction 1 in most cases and increased from the phloem side, while PsWOXG expression was not clearly bound to a certain fraction. Based on the data, the role of the CLE41/44-PXY-WOX signaling module in regulating P. sylvestris cambial growth is discussed.

Fusing tree-ring and permanent sample plot data to model influences of climate and thinning on tree growth in larch plantations in northeast China

An improved understanding of the effects of thinning and climate on tree growth is essential to adopting adaptive forest management strategies under climate change. In this study, we developed a climate-sensitive individual-tree growth model for Changbai larch (Larix olgensis) in northeast China by fusing tree-ring and permanent sample plot data. We assessed the impacts of tree age, competition, site condition, thinning, and climate on radial growth using the mixed-effects modeling approach. Results showed that the radial growth rate of Changbai larch decreased with increasing cambial age and competition intensity. Radial growth was negatively associated with summer water deficit and positively associated with spring growing degree-days. Radial growth also responded positively to mean annual precipitation of the previous year. In addition, a significant positive effect of thinning on radial growth was observed. The magnitude of thinning effects was affected by thinning intensity and time elapsed since the thinning. Hierarchical partitioning analysis showed that cambial age was the most important factor affecting growth (relative contribution 35.96%), followed by competition (31.42%), climate (19.24%), thinning (8.40%), and site condition (4.98%). Compared to unthinned plots, moderate- and high-intensity thinning significantly enhanced the radial growth under unfavorable climates, indicating that thinning has great potential to mitigate the negative effects of future climate. Disentangling different sources of variations in ring width will help advance our understanding of the factors driving radial growth and reduce the uncertainty in forest management decisions.

Detecting the changes of wood properties with respect to elapsed years since wood formation by the eigenvalue distribution of near infrared spectral matrices

The effects of aging on wood properties are usually evaluated based on cambial age, with the assumption that the properties do not change once the wood has formed. This study examined changes in wood properties with the number of years elapsed since wood formation. Near-infrared (NIR) spectra were acquired from various positions of 20 sample trees, and changes in the spectra were examined with respect to elapsed years. We considered changes in multiple traits inclusively, rather than individually, using the distribution of eigenvalues calculated from NIR spectral matrices. The diffusion of eigenvalues with an increase in elapsed years followed Dyson’s Brownian motion. The gradual increase in the first eigenvalue, which is equivalent to the Helmholtz-free energy, indicates that the xylem in the heartwood changes to a more ordered physical state over time. The variations in Shannon entropy and density matrix with elapsed years revealed the irreversibility of the aging process. The proposed method is independent of a specific coordinate system and can, therefore, be applied using a wide variety of information other than that obtained from NIR spectra.

Plant-Programmed Cell Death-Associated Genes Participation in Pinus sylvestris L. Trunk Tissue Formation.

Molecular genetic markers of various PCD (programmed cell death) variants during xylo- and phloemogenesis have been identified for the first time in Scots pine under lingonberry pine forest conditions in Northwest Russia (middle taiga subzone). PCD is a genetically determined process. Gene profiles of serine and cysteine proteases (endopeptidases), endonucleases, and metacaspases families are often considered markers of the final xylogenesis stage. In the present study, we examined the gene expression profiles of the BFN (bifunctional endonuclease) family-BFN, BFN1, BFN2, BFN3, and peptidase (cysteine endopeptidase, CEP and metacaspase, MC5) in the radial row, in addition to the vascular phloem and cambium (F1), differentiating xylem (F2), sapwood (SW), and transition zone during the active cambial growth period of uneven-aged pine trees (25-, 63- and 164-cambial age (c.a.) years old). We have shown that the expression patterns of the PCD-related genes did not depend on the cambial age but were largely determined by plant tissue type. In the radial row F1-F2-SW, we studied the activities of enzymes, including sucrose in metabolism (sucrose synthase, three forms of invertase); antioxidant system (AOS) enzymes (superoxide dismutase, catalase); and peroxidase andpolyphenol oxidase, which belonged to AOS enzymes and were involved in the synthesis of phenolic components of cell walls. The activity of the enzymes indicated that the trunk tissues of pine trees had varying metabolic status. Molecular genetic PCD regulation mechanisms during xylem vascular and mechanical element formation and parenchyma cells' PCD during the formation of Scots pine heartwood were discussed.