Ring-width Variations Research Articles

<i></i>Ring width distribution as a valuable anatomical trait for predicting bending strength and rigidity in European oak wood beams

Ring width variability affects the elasticity and strength of wood members. This study was conducted to determine which dispersion statistics of annual ring width distributions measured in cross section in European oak (Quercus robur L.) wood beams are useful as covariates in models for predicting modulus of elasticity (MOE) and modulus of rupture (MOR). For this purpose, 21 European oak trees growing in north-western Spain were felled, logged and sawn. The planks obtained were air-dried and surfaced into beams (50×100×2,000 mm), which were visually graded according to the UNE 56544:2022 standard. MOE, MOR, moisture content and density (determined according to EN 408:2010 standard) and abundance of sapwood and ring widths were determined in 30 beams apt for structural purposes. MOE was significantly related to standard deviation, variance and interquartile range of the ring width distribution in the beam. MOE was also related to mean ring width (r =-0.52, p<0.01) and maximum ring width per beam (r =-0.54, p<0.01), an easy to measure variable. MOR was also related to ring width distribution parameters, although yielding lower r values. The influence of ring width evenness and maximum ring width can be considered to improve visual strength grading standards for European oak timber.

A process-based model of climate-driven xylogenesis and tree-ring formation in broad-leaved trees (BTR).

The process-based xylem formation model is an important tool for understanding the radial growth process of trees and its influencing factors. While numerous xylogenesis models for conifers have been developed, there is a lack of models available for non-coniferous trees. In this study, we present a process-based model designed for xylem formation and ring growth in broad-leaved trees, which we call the Broad-leaved Tree-Ring (BTR) model. Climate factors, including day length, air temperature, soil moisture, and vapor pressure deficit, drive daily xylem cell production (fibers and vessels) and growth (enlargement, wall deposition). The model calculates the total cell area in the simulated zone to determine the annual ring width. The results demonstrate that the BTR model can basically simulate inter-annual variation in ring width and intra-annual changes in vessel and fiber cell formation in Fraxinus mandshurica (ring-porous) and Betula platyphylla (diffuse-porous). The BTR model is a potential tool for understanding how different trees form wood and how climate change influences this process.

Radial Variation in Growth Ring Widths with Reference to Age from Juvenile Wood to Mature Wood of Five Selected Indian Woods

Radial Variation in Growth Ring Widths with Reference to Age from Juvenile Wood to Mature Wood of Five Selected Indian Woods

Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

Dendrochronology is a technique that can be applied as a retrospective monitoring (RM) approach to evaluate the performance of nutrient application in forest ecosystems. Applying the RM approach across operations lacks experimental controls, which may adversely affect accuracy and precision of estimates due to greater mismatches in stand conditions between treated and untreated plots. To test the rigor of the RM approach, we collected increment cores of coastal Douglas fir (Pseudotsuga menziesii var. menziesii) at eight sites of an experiment where stands were fertilized in 1971. First, we tested the approach under ideal conditions by sampling from treated and untreated plots of the experiment. Second, we tested the approach using newly established surrogate control (SC) plots, which differed in ecological site classification from those of the treated plots to understand how robust the approach was to mismatches in conditions between treated and untreated samples. We hypothesized that detrending ring width would mitigate error in responses to nutrient application resulting from mismatches in site classification. Within the experiment, the approach indicated an average increase of 15% (5% to 26%, p < 0.05) growth response to operational doses of urea. Different responses were found when the analysis relied on SC plots. Detrending low-frequency variation in ring widths eliminated differences in results arising, at least in part, to mismatches in site class. However, it also reduced the growth response using the experimental control plots to 10%. Dendrochronology with detrending shows promise in the ability to mitigate variation introduced by mismatches in ecological site classification that may occur in operational monitoring. Based on these results, we see potential to implement RM with operations to evaluate and optimize stand selection criteria.

Response sensitivity processes of conifers radial growth to climate factors based on tree ring width variations

The tree radial growth process exhibits complex signals in response to climate change. These signals can significantly influence the tree growth process. Essential physiological factors play a critical role in determining growth-response differences. However, the mechanisms affecting the nonlinear response of conifer species growth to climate change have yet to be fully elucidated. In this study, we measured the characteristic signals of growth process-wide (narrow) rings from two conifer species, Qinghai spruce (Picea crassifolia Kom.) and Chinese pine (Pinus tabuliformis Carr.) in the subalpine zone at the southern edge of the Tengger Desert, and analyzed their phenology and seasonal water-heat utilization dynamic mechanisms using the process-based Vaganov-Shashkin model (VS-oscilloscope). Our investigation demonstrates that both species are sensitive to temperature, although P. crassifolia is more responsive to temperature-induced drought stress. Furthermore, the phenology and seasonal water-heat utilization dynamics are the main driving forces behind the climate response sensitivity and radial growth trends of conifer species. The study revealed earlier dormancy for both species in narrow rings, as well as earlier growth initiation for P. crassifolia. Additionally, temperature was identified as the key cause of growth decline trends in the middle growing season. The limited soil moisture caused by temperature-induced deficits in the end growing seasons was also responsible for the frequent narrow rings of P. tabuliformis. Therefore, we propose that management and conservation measures for subalpine ecosystems should be formulated based on the response sensitivity and physiological mechanism of conifer species.

Tree Ring Width Responses of Pinus densiflora and Robinia pseudoacacia to Climate Variation in the Mount Tai Area of Northern China

To effectively combat climate change and put plans in place to enhance the health and quality of forests, research on the connections between long-term climate change and tree ring width is essential. Here, Pinus densiflora Siebold & Zucc. and Robinia pseudoacacia L. in the Mount Tai area were studied. Specifically, their tree ring width characteristics were investigated according to the principles of dendrochronology, based on the analysis of multiyear climate data (1972–2022). The results showed that (1) the variation in tree ring width of Pinus densiflora Siebold & Zucc. generally decreased. Its basal area increment sequence presented a “growth-decline” change process. The trend for Robinia pseudoacacia L. was stability at first and then a reduction. Its basal area increment sequence presented a “growth-stabilization” change process. (2) The standard chronologies of both tree species contained more environmental information than the residual chronologies, rendering the former more appropriate for analysis. (3) The tree ring width of Pinus densiflora Siebold & Zucc. was positively correlated with the mean maximum temperature in February, March, and July, the mean temperature in May, and the mean precipitation in December of the previous year and June of the current year. The tree ring width of Robinia pseudoacacia L. was positively correlated with the mean and maximum temperatures in October of the previous year, the mean maximum temperature in May of the current year, and the mean temperature in July of the current year. This variable was positively correlated with the mean precipitation in November of the previous year and July of the current year but negatively correlated with the mean minimum temperature in November of the previous year and the mean temperature in December of the current year. (4) During 1987–1988, 1994–1995, 2005–2006, and 2018–2019, the tree ring width was restricted by rising temperatures and low precipitation, with variations in tree ring width observed in various hydrological periods. (5) The moisture index, followed by the warmth index, precipitation and temperature, was the primary climate factor determining the tree ring width in both tree species.

An Overview of Extreme Years in Quercus sp. Tree Ring Records from the Northern Moldavian Plateau

In this study, we made use of a regional oak tree-ring network from six stands that cover the northern Moldavian Plateau (eastern Europe) to analyze how different tree ring parameters (i.e., early wood tree-ring width, late wood tree-ring width, and total tree-ring width) of Quercus sp. are influenced by the occurrence of extreme climatic events (e.g., long-lasting drought events). In order to explore the influence of extreme hydroclimatic events on tree ring width, we have selected each of the six most extreme positive and negative years of tree growth and addressed the seasonal cycle of tree growth in comparison with the main climatic parameters, then evaluated both the current and lagged consequences of extreme hydroclimatic events on tree ring width and the capacity of trees to recover. Our results indicate that the variability of oak tree ring width from the Moldavian Plateau is mainly influenced by the availability of water resources, and that an important limiting growth factor for Quercus sp. is the occurrence of long-lasting drought events, e.g., at least two years in a row with severe drought conditions.

Climate Overrides the Influence of Microsite Conditions on Radial Growth of the Tall Multi-Stemmed Shrub Alnus alnobetula at Treeline.

Green alder (Alnus alnobetula), a tall multi-stemmed deciduous shrub, is widespread at high elevations in the Central European Alps. Its growth form frequently leads to asymmetric radial growth and anomalous growth ring patterns, making development of representative ring-width series a challenge. In order to assess the variability among radii of one shoot, among shoots belonging to one stock and among stocks, 60 stem discs were sampled at treeline on Mt. Patscherkofel (Tyrol, Austria). Annual increments were measured along 188 radii and analyzed in terms of their variability by applying dendrochronological techniques. Results revealed a high agreement in ring-width variation among radii of one shoot, among shoots of one stock and largely among stocks from different sites, confirming the pronounced limitation of radial stem growth by climate forcing at the alpine treeline. In contrast to this, a high variability in both absolute growth rates and long-term growth trends was found, which we attribute to different microsite conditions and disturbances. These factors also override climate control of radial growth under growth-limiting environmental conditions. Based on our findings we provide recommendations for the number of samples needed to carry out inter- and intra-annual studies of radial growth in this multi-stemmed clonal shrub.

Advanced Workflow for Taking High-Quality Increment Cores - New Techniques and Devices

In dendroecological research, precise dating of each single growth ring is a basic requirement for all studies, focusing on ring-width variations only, chemical or isotope analyses, or wood anatomical studies. Independent of the sampling strategy for a certain study (e.g., climatology, geomorphology), the way samples are taken is crucial for their successful preparation and analyses. Until recently, it was sufficient to use a (more or less) sharp increment corer to obtain core samples that could be sanded for further analyses. Since wood anatomical characteristics can be applied to long time series, the need to obtain high-quality increment cores has taken on a new meaning. Essentially, the corer needs to be sharp(ened) when used. When coring a tree by hand, there are some problems in handling the corer, resulting in the hidden occurrence of micro cracks along the entire core: When starting to drill by hand, the drill bit is strongly pressed against the bark and the outermost ring until the thread has fully entered the trunk. At the same time, the drill bit is moved up and down as well as sideward. Then, the corer is drilled all the way into the trunk; however, it is necessary to stop after each turn, change the grip, and turn again. All these movements, as well as the start/stop-coring, puts mechanical stress on the core. The resulting micro cracks make it impossible to create continuous micro sections, as they fall apart along all these cracks. We present a protocol to overcome these obstacles by applying a new technique using a cordless drill to minimize these problems when coring a tree, as well as its effect on the preparation of long micro sections. This protocol includes the preparation of long micro sections, as well as a procedure to sharpen corers in the field.

Advanced Workflow for Taking High-Quality Increment Cores - New Techniques and Devices

In dendroecological research, precise dating of each single growth ring is a basic requirement for all studies, focusing on ring-width variations only, chemical or isotope analyses, or wood anatomical studies. Independent of the sampling strategy for a certain study (e.g., climatology, geomorphology), the way samples are taken is crucial for their successful preparation and analyses. Until recently, it was sufficient to use a (more or less) sharp increment corer to obtain core samples that could be sanded for further analyses. Since wood anatomical characteristics can be applied to long time series, the need to obtain high-quality increment cores has taken on a new meaning. Essentially, the corer needs to be sharp(ened) when used. When coring a tree by hand, there are some problems in handling the corer, resulting in the hidden occurrence of micro cracks along the entire core: When starting to drill by hand, the drill bit is strongly pressed against the bark and the outermost ring until the thread has fully entered the trunk. At the same time, the drill bit is moved up and down as well as sideward. Then, the corer is drilled all the way into the trunk; however, it is necessary to stop after each turn, change the grip, and turn again. All these movements, as well as the start/stop-coring, puts mechanical stress on the core. The resulting micro cracks make it impossible to create continuous micro sections, as they fall apart along all these cracks. We present a protocol to overcome these obstacles by applying a new technique using a cordless drill to minimize these problems when coring a tree, as well as its effect on the preparation of long micro sections. This protocol includes the preparation of long micro sections, as well as a procedure to sharpen corers in the field.

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.

Variations in Ring Width and Gas Components in Wood of Larch Trees Injured by the Fire of 1908

Variations in Ring Width and Gas Components in Wood of Larch Trees Injured by the Fire of 1908

Blue is the fashion in Mediterranean pines: New drought signals from tree-ring density in southern Europe

Long-term records of tree-ring width (TRW), latewood maximum density (MXD) and blue intensity (BI) measurements on conifers have been largely used to develop high-resolution temperature reconstructions in cool temperate forests. However, the potential of latewood blue intensity (LWBI), less commonly used earlywood blue intensity (EWBI), and delta (difference between EWBI and LWBI, dBI) blue intensity in Mediterranean tree species is still unexplored. Here we developed BI chronologies in moist-elevation limits of the most southwestern European distribution of Pinus nigra subsp. salzmanii Arnold. We tested whether BI variables derived from tree rings of black pine are better proxies than ring-width variables to reconstruct long-term changes in climatic factors and water availability. For this we applied correlations and regression analyses with daily and monthly climate data, a spatial and temporal drought index (Standardized Precipitation-Evapotranspiration Index-SPEI) and Vapour Pressure Deficit (VPD), as well as atmospheric circulation patterns: North Atlantic Oscillation (NAO), Southern Oscillation Index (SOI) and Western Mediterranean Oscillation (WeMO). We found a positive relation between black pine growth (RW) and temperature during the winter preceding the growing season. Among all variables LWBI and dBI were found to be more sensitive than TRW to SPEI at low-elevation site, with EWBI series containing an opposite climatic signal. LWBI and dBI were significantly related to June and September precipitation at high-elevation site. Winter VPD was related with higher EWI and LWI series, whereas dBI and EWBI were related with January SOI and February NAO. We confirm the potential of long-term dBI series to reconstruct climate in drought-prone regions. This novel study in combination with other wood anatomical measurements has wide implications for further use of BI to understand and reconstruct environmental changes in Mediterranean conifer forests.

Isolated Trees in Two Tibetan Plateau Treelines Reveal Growth Plasticity to Harsh Conditions of the Little Ice Age

Trees greater than 150 years old growing in the current treelines were most likely isolated tree outposts above previous treelines of the Little Ice Age (LIA). An intuitive question is, how did these isolated trees grow at such a high elevation in the cold environment? Here, we tackle this question using tree-ring width data of the Northern Hemisphere’s highest treelines at 4900 m a.s.l. (Basu) and 4680 m a.s.l. (Langkazi) on the Tibetan Plateau. The results showed that an age-related exponential growth trend did not exist in most of the ring-width sequences of the sampled trees. The values of ring widths in the isolated trees had a similar pattern of probability distribution during and after the LIA. The coefficients of variation in ring widths of the isolated trees were significantly greater than those of the non-isolated trees in their common growth period. Synchronicity of annual change in radial growth among trees varied in time. These results indicated that the isolated trees in the LIA developed an adaptive ability to slow down radial growth rate and modulate growth synchronicity among individuals in cold stressful environments. Our study highlights growth plasticity in isolated trees above treelines for coping with harsh conditions in the LIA.

Warming effects on tree-ring variables in P. hartwegii Lindl. at the extremes of its natural elevational distribution in central Mexico

In alpine forests, the impact of warming differs at the upper and lower extremes of the elevation gradient causing trees to compensate through different adaptive mechanisms. The objective was to retrospectively evaluate the radial growth response to recent interannual climate variation in Pinus hartwegii trees growing at the extremes of their elevational gradient on two volcanic mountains in central Mexico (La Malinche and Nevado de Toluca). Increment cores collected from 174 P. hartwegii trees were used to estimate time-series of growth ring including ring width and density variables, as well as basal area increment (BAI) and ring biomass (BIO) for 1964–2016. Differences in average radial growth and time-trends of ring variables in response to climate variables were estimated based on correlations of ring variables, BAI, and BIO with inter-annual variation in temperature, rainfall, and length of the frost-free period (FFP). Results showed higher average values of ring width and density variables, as well as BAI and BIO (i.e., higher productivity) at low elevation on both mountains. Time-trends for BAI and BIO were positive at both ends of the elevation gradient, but ring width and density variables followed opposite trends. Inter-annual variation of ring variables was explained more by temperature than by rainfall or FFP; however, temperature was negatively correlated with RW and positively with RD, even though BAI and BIO were positively correlated with temperature (All them with P < 0.001) at both elevational end on both mountains. For most of the ring variables, the total variation explained by the ANOVA model was more related to the linear warming trend (greater than 67%). Warming is affecting radial growth of P. hartwegii trees differently at high versus low elevation on both mountains, showing warning signs from the perspective of functional traits, but not in terms of productivity.

Relationship between the xylem maturation process based on radial variations in wood properties and radial growth increments of stems in a fast-growing tree species, Liriodendron tulipifera

Promoting wood utilization from fast-growing tree species is one solution to address supply and demand issues relating to wood resources while sequestering carbon dioxide in large quantities. Information on the quality of wood from fast-growing tree species and its relationship with changes in stem size is essential for promoting the establishment of plantations and wood utilization of fast-growing tree species. To explore the relationship between the xylem maturation process and radial growth increments of stems in fast-growing tree species, we examined radial variations in annual ring widths and wood properties in Liriodendron tulipifera in Japan. The cambial ages at which current annual increment and mean annual increment values were greatest were 4.9 years and 7.4 years, respectively. Based on radial variations evaluated by mixed-effects modeling of wood properties, all properties increased or decreased near the pith before becoming stable towards the cambium. Changing ratios of multiple wood properties at 1-year intervals became stable after a cambial age of 9 years. These results point to an ecological strategy in L. tulipifera, in which there is a tradeoff between radial growth increments and wood properties. As part of this strategy, in response to competition among individual trees within a stand, the tree produces a large volume of xylem with lower physical and mechanical properties, allowing it to increase its volume faster than that of the surrounding trees. Subsequently, it produces xylem that is more stable, with greater physical and mechanical properties. This wood forms at a slower growth rate compared to the xylem that forms at the time of initial tree growth. Based on the ecological strategy adopted by L. tulipifera, wood that forms before a cambial age of 9 years can be used for utility applications, and wood that forms after a cambial age of 9 years can be used for structural applications.

Modeling the tensile mechanical properties of silver birch timber boards

In this paper, the variability of tensile mechanical properties of silver birch timber is investigated and models for the prediction of tension strength and stiffness are developed. Through visual inspections and non-destructive tests, various strength and stiffness related indicators are identified. Destructive tension tests are subsequently performed for the determination of strength and stiffness. On each timber board, strains are measured at four localized regions, whereby, the stiffness of knot sections and clear wood sections are determined. Variability in strength, stiffness, density, knots, grain angle, and annual ring width are investigated along with the relationships between them. A hierarchical model is developed for the prediction of timber board stiffness and the reduction of stiffness due to knots. Models for the prediction of timber board strength and knot cluster strength are developed according to equality and inequality information of the failed specimens, by means of censored regression analysis. Results indicate suitable global and local predictions for silver birch timber, given the dynamic modulus of elasticity, median slope of grain, and knot geometries.

Dendroclimatological Analysis of Fir (A. borisii-regis) in Greece in the frame of Climate Change Investigation

The potential correlation between fir tree-ring width (Abies borisii regis Mattf.) variability and the respective variability of the main climatic parameters in the region of University Forest of Pertouli (central Greece) are being analyzed in the current study, taking into consideration a 60-year period (1961–2020). Correlation and response function analyses were applied to examine the climate–tree-growth relationship. Precipitation was found to be the most crucial and driving factor that most intensively influences the tree growth of A. borisii-regis trees under Mediterranean climate conditions. It was evident that this species is characterized by drought sensitivity and even a short and mild drought event could significantly influence adversely its growth and productivity. June, May and July precipitation present the higher and statistically significant correlation of monthly precipitation with tree-ring width, affecting the ring-width variability by 31.2%. Temperature (mean, max or min) does not seem to highly influence the tree growth, despite the obvious and statistically significant trend increase that has been recorded in the last decades within the frame of climate change. June maximum temperature presents a strong negative correlation with tree-ring width, while April maximum temperature is positively correlated with tree-ring width. The combined impact of precipitation and max temperatures on tree-ring growth is 38.5%. Snow did not reveal any statistically significant correlation to tree-ring width, independent of the height of monthly snow accumulation. A. borisii-regis grown in high altitudes in the Mediterranean region demonstrate high adaptability to the recorded temperature increase and could potentially be able to adapt in future to even warmer climate conditions. The constructed tree-ring chronology could be utilized towards the implementation of further dendroclimatological analyses and climate reconstruction.

Inter-annual and inter-species tree growth explained by phenology of xylogenesis.

Summary Wood formation determines major long‐term carbon (C) accumulation in trees and therefore provides a crucial ecosystem service in mitigating climate change. Nevertheless, we lack understanding of how species with contrasting wood anatomical types differ with respect to phenology and environmental controls on wood formation.In this study, we investigated the seasonality and rates of radial growth and their relationships with climatic factors, and the seasonal variations of stem nonstructural carbohydrates (NSC) in three species with contrasting wood anatomical types (red oak: ring‐porous; red maple: diffuse‐porous; white pine: coniferous) in a temperate mixed forest during 2017–2019.We found that the high ring width variability observed in both red oak and red maple was caused more by changes in growth duration than growth rate. Seasonal radial growth patterns did not vary following transient environmental factors for all three species. Both angiosperm species showed higher concentrations and lower inter‐annual fluctuations of NSC than the coniferous species.Inter‐annual variability of ring width varied by species with contrasting wood anatomical types. Due to the high dependence of annual ring width on growth duration, our study highlights the critical importance of xylem formation phenology for understanding and modelling the dynamics of wood formation.

Did stand opening 60 years ago predispose a European beech population to death?

Widespread increases in tree mortality have fueled the debate on the mechanisms of heat- and drought-related tree death. While much research focused on the immediate causes of tree death, the role of predisposing factors for death is not well understood. We employed tree-ring and climate sensitivity analysis of growth to study the importance of legacy effects of past disturbances for growth patterns and a recent mortality burst in a protected European beech (Fagus sylvatica) forest, comparing groups of live and recently died trees in the same stand. Live and dead trees showed a decade-long decrease in radial growth since the severe 1976 drought, which indicates that the high mortality in the last two decades is not solely caused by recent drought spells, but that trees were apparently predisposed by previous events to death decades later. An even more distant event than the 1976 drought that has imprinted on the chronologies is the severe 1947 drought in combination with extensive logging at that time. It appears that stand opening 60 and 40 years ago due to high immediate drought mortality in conjunction with heavy logging resulted in much higher inter-annual ring width variability with more extreme negative and positive pointer years in the subsequent years, and led to permanent reduction in tree health. We identified the first derivative of the ring width curve as the most reliable early-warning signal of a predisposition to drought-induced death, while inter-annual growth variability and growth resistance and resilience to drought were less suited. We suggest that the causes of recent climate warming-related dieback of beech and other temperate hardwood forests may only be fully grasped, when the imprint of past stress events on growth and vitality is understood. The physiological mechanisms causing legacy effects with long delay of death require further study.