Annual Ring Width Research Articles

Nanomechanical/Micromechanical Approach to the Problems of Dendrochronology and Dendroclimatology

The most widespread approach in dendrochronology (wood dating) and dendroclimatology (climate reconstruction) is based on measurement of the width of annual growth rings by analyzing optical images of wood cross sections. This approach is quite efficient and easy to implement but it has inherent drawbacks. Raw data for these techniques originate from the optical properties of the wood surface, which are not directly related to other properties of wood, mechanical properties in particular. This paper describes a new quantitative approach applicable to dendrochronology and dendroclimatology based upon measurement of the micromechanical properties of wood by employing nanoindendation and digital sclerometry. It yields not only the width of annual growth rings and early and late wood layers with an accuracy not inferior to optical methods, but also rich data on the mechanical properties of the wood with a high spatial resolution that could be brought to subcellular scale if necessary. This data can be used for the dendrochronological analysis of archeological finds and the evaluation of climatic parameters during tree growth with a time resolution of up to a month or even better, which is unlike other common methods with a time resolution of one year. Moreover, the detailed continuous profiling of local mechanical properties can form a basis for improving our understanding of the nature and mechanisms of the formation of macromechanical properties important for applications and can clarify the climate factors that have the greatest impact on such properties.

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.

Annual ring width in the arctic-alpine dwarf-shrub species Salix herbacea - Dataset from long-term alpine ecosystem research in central Norway (LTAER-NO)

Here, we present a datapaper containing microscopically measured data of annual ring widths in the arctic-alpine dwarf-shrub species Salix herbacea (central Norway). The dataset will be updated with future measurements.

Annual ring width in the Mediterranean-alpine shrub species Cytisus galianoi - dataset from long-term alpine ecosystem research in the Sierra Nevada, Spain (LTAER-ES)

This is a datapaper including microscopically measured data of annual ring widths from the Mediterranean-alpine shrub species Cytisus galianoi (Sierra Nevada, Spain). The dataset will be updated with future measurements.

Радиальный рост ели (Picea abies (L.) Karst. × P. obovata Ledeb.) в условиях горных разработок

A dynamic of radial growth of spruce near a quarry of kimberlite pipes is investigated in this study. The quarry is considered as a potential source of anthropogenic impact. The research takes place at the central part of the White Sea Kuloi plateau, at the diamond deposit named after M.V. Lomonosov. The wood cores for dendrochronological analysis are from six trail plots located at different distances from the active quarry. The annual radial increment of spruce in all plots ranges from medium to high or very high. It is noticed that spruce trees have different durations of depression and expression cycles. The growth rates of the trees from the same plot do not coincide, or they show similarities to certain periods of tree’s life with cyclical patterns. In most cases, minimum and maximum extremes are observed near the well-known values of solar activity cycles. An inverse relationship is found between duration and repetition of the cycles. The measurements from all trail plots show a decrease in the amplitude of radial growth, which started in 2000. It took much greater extent in the period from 2010 to 2019. The samples of the spruce, which were taken from the oligotrophic habitats located near the quarry, indicate an increase of width of annual rings in the last 10–20 years. Fifty percent of them reveal a distinct radial extent. The trees from the most distant trail area are characterized by high simultaneity in the dynamics of the annual layers. Moreover, it is found a decrease in the maximum value of radial growth relative to the entire series of observations. Likewise, a reduce in the amplitude of increments is noted as a rise in the repeatability of relative growth indices below the regular values. It can be assumed that the change in the trend of radial growth in spruce in the oligotrophic habitats is mostly associated with the formation of а depression cone and, as a result, a general lowering of the groundwater level. For citation: Barzut O.S., Surso M.V. Radial Growth of Spruce (Picea abies (L.) Karst. × P. obovata Ledeb.) in the Conditions of Mining Impact. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 58–72. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-58-72

Response of Radial Growth of Mongolian Pine to Climate Factors in Mu Us Sandy Land, Inner Mongolia

The Mu Us sandy land is located on the northwestern edge of the East Asian monsoon region in China, and its environment is fragile and sensitive to climate change. To explore the response of the radial growth of Mongolian pine (Pinus sylvestris var. mongolica), the main afforestation tree species in this area, to climate change, a traditional method of tree-ring climatology was adopted to analyze the correlation of radial growth to climatic factors in the region from 1959 to 2019 based on annual ring widths of Mongolian pine. The results showed that water and heat conditions in May of the current year were the main climatic factors restricting the growth of this tree species in the Mu Us sandy land, mainly manifested as a negative correlation with the average temperature and maximum temperature in May of the current year, while a positive correlation with precipitation in this month. In addition, the average temperature and minimum temperature in March of the current year are also restricted to tree growth. Mongolian pine is one of the excellent tree species suitable for desertification control and afforestation in the Mu Us sandy land. Under the background of the changing climate, becoming warmer and drier, the effect of drought stress on the radial growth of Mongolian pine will become more and more prominent. If the temperature continues to increase in the future, the radial growth and carbon sequestration of Mongolian pine in Mu Us sandy land will be severely affected.

Effects of radial growth rate on juvenile wood properties of Pinus sylvestris planted in Mongolia

The establishment of forest plantations in boreal zones in Mongolia is important for wood production as well as carbon dioxide fixation. The present study aims to elucidate the juvenile wood properties (basic density, modulus of elasticity [MOE], modulus of rupture [MOR], and compressive strength parallel to grain) of plantation-grown Pinus sylvestris to promote the establishment of plantations. In addition, the effect of the radial growth rate on wood properties was also evaluated using a linear mixed-effects model. In the juvenile wood phase, wood properties were increased from the pith to bark side based on the results of model selections. Up to the 20th annual ring from the pith, the estimated mean values of basic density, MOE, MOR, and compressive strength were 0.40 g/cm3, 5.35 GPa, 65.1 MPa, and 28.4 MPa, respectively. Variance component ratios of growth categories were low in wood properties, with the exception of basic density, suggesting that the radial growth rate did not affect wood properties in the juvenile wood phase in this species growing in Mongolia. Based on the results obtained in the present study, we have concluded that although basic density in the faster growth category yielded relatively lower values, appropriate radial growth promotion during the initial stage of growth in P. sylvestris trees planted in Mongolia exerted no negative impact on juvenile wood properties. Keywords: annual ring width, basic density, compressive strength, modulus of elasticity, modulus of rupture

Long-Term Climate Sensitivity of Resin-Tapped and Non-Resin-Tapped Scots Pine Trees Based on Tree Ring Width and Blue Intensity

The resin tapping of pine trees in Poland ended in the early 1990s. However, we can still find individual trees, and sometimes larger groups of trees, that were tapped. This study focused on the effect of the mechanical wounding of trees during resin tapping on the growth and climatic sensitivity of pine trees. The study concerned a 160-year-old pine stand in northwestern Poland in which resin tapping was last performed in the 1970s. All the trees had remained standing because of their high quality, which had destined them for seed collection. The stand included both resin-tapped (RT) and non-RT (NRT) trees. Our study was based on a dendrochronological analysis of two signals—annual tree ring widths (TRWs) and their delta blue intensity (DBI). We observed a significant increase in annual TRW after resin tapping had ceased, alongside a decrease in the DBI. The temporal stability in growth response was examined using daily climatic correlations from 1921 to 2021. It was found that the climatic sensitivity of RT and NRT pines was similar. There were differences in only some of the years, most while resin tapping was occurring, and then approximately 20 years after the resin tapping had ceased. However, these were small differences that mainly related to the strength of the correlation. It was also discovered that we can obtain different types of information from the study of TRWs and DBI.

Forest growth responds more to air pollution than soil acidification.

The forests of central Europe have undergone remarkable transitions in the past 40 years as air quality has improved dramatically. Retrospective analysis of Norway spruce (Picea abies) tree rings in the Czech Republic shows that air pollution (e.g. SO2 concentrations, high acidic deposition to the forest canopy) plays a dominant role in driving forest health. Extensive soil acidification occurred in the highly polluted "Black Triangle" in Central Europe, and upper mineral soils are still acidified. In contrast, acidic atmospheric deposition declined by 80% and atmospheric SO2 concentration by 90% between the late 1980s and 2010s. In this study we oserved that annual tree ring width (TRW) declined in the 1970s and subsequently recovered in the 1990s, tracking SO2 concentrations closely. Furthermore, recovery of TRW was similar in unlimed and limed stands. Despite large increases in soil base saturation, as well as soil pH, as a result of repeated liming starting in 1981, TRW growth was similar in limed and unlimed plots. TRW recovery was interrupted in 1996 when highly acidic rime (originating from more pronounced decline of alkaline dust than SO2 from local power plants) injured the spruce canopy, but recovered soon to the pre-episode growth. Across the long-term site history, changes in soil chemistry (pH, base saturation, Bc/Al soil solution ratio) cannot explain observed changes in TRW at the two study sites where we tracked soil chemistry. Instead, statistically significant recovery in TRW is linked to the trajectory of annual SO2 concentrations or sulfur deposition at all three stands.

Efficiency of early selection for growth and wood quality traits of slash pine in three progeny trials in southern China

Abstract A firm understanding of the early selection efficiency of ring width and wood quality traits is a prerequisite for breeding of higher growth rates and wood quality of slash pine (Pinus elliottii Engelm.). To accomplish effective early selection for the studied traits, wood core samples were collected from 360 trees of 20 open-pollinated families from three slash pine rotation-aged (harvest age) genetic trials. Wood cores were measured by SilviScan, and the annual patterning, heritability, age-age genetic correlation and efficiency of early selection for ring width, modulus of elasticity (MOE), microfibril angle (MFA) and wood density for early to reference age (age 27) were investigated. The greatest annual ring width was observed at age 4, and this trait decreased gradually toward the bark. Different radial trends were found for MOE and MFA. Wood density was lowest near the pith and then increased steadily with age. Overall, heritability was moderate to high for all area-weighted wood quality traits. Very high age-age genetic correlation values were observed for all traits researched. Estimates of efficiency for early selection indicated that the optimal age of early selection for ring width was 9–12 years, while that for area-weighted MOE, MFA and wood density was 7–8 years.

Physical and Acoustical Properties of Wavy Grain Sycamore Maple (Acer pseudoplatanus L.) Used for Musical Instruments

The wood used in the construction of musical instruments is carefully selected, being the best quality wood from the point of view of the wood structure. However, depending on the anatomical characteristics of the wood, the resonance of wood is classified into quality classes. For example, sycamore maple wood with curly grains is appreciated by luthiers for its three-dimensional optical effect. This study highlights the statistical correlations between the physical and anatomical characteristics of sycamore maple wood and its acoustic and elastic properties, compared to the types of wood historically used in violins. The methods used were based on the determination of the acoustic properties with the ultrasound method, the color of the wood with the three coordinates in the CIELab system and the statistical processing of the data. The sycamore maple wood samples were divided into anatomical quality classes in accordance with the selection made by the luthiers. The results emphasized the multiple correlations between density, brightness, degree of red, width of annual rings, acoustic and elastic properties, depending on the quality classes. In conclusion, the work provides a valuable database regarding the physical–acoustic and elastic properties of sycamore maple wood.

Investigation of Trees' Sensitivity to Drought: A Case Study in the Opole Region, Poland

<i>Pinus sylvestris</i> L. is the most common tree species growing in Poland. Trees of this species are considered to be resistant to difficult meteorological conditions; however, in the past decades, many of them have died and been cut down by foresters. The measurements of the annual tree ring width can provide information on how trees respond to drought events. This study aimed to investigate the potential differences between healthy and declining trees (identified as trees to be cut down by foresters). For this purpose, we collected samples of five trees from each group and analysed them using dendrochronological and quantitative wood anatomy approaches. We measured ring width index (RWI) chronologies for healthy and declining trees and compared them with climate data. Additionally, we compared some anatomical features of trees from both groups as cell wall thickness (CWT) and lumen area (LA). The conducted analyses showed significant differences between healthy and declining trees. In particular, declining trees were characterised by lower RWI, LA and CWT values, especially in the past 20 years, and showed greater sensitivity to changes in temperature and humidity than healthy trees.

Basic Characteristics of Black Locust (Robinia pseudoacacia L.) Wood Grown Under Different Site Conditions: A Review

This study provides an overview of the basic characteristics of Robinia pseudoacacia cultivated throughout Europe. After studying the literature, we concluded that air temperature and precipitation amounts significantly influenced the annual ring width of R. pseudoacacia. In addition, the light, water, and nutrient supply affected tree growth by increasing growth intensity, thus reducing vessel diameters and pieces per unit area. Black locust wood grown in Belgium has a higher volumetric shrinkage (16 %) and tangential shrinkage (8.8 %) and a considerably higher modulus of elasticity (15,700 MPa) compared to wood from Poland and Hungary. The vessel diameters measured in the latewood of Robinia wood grown in Hungary (70-140 μm) exceeded those in Greece (24 μm). Knowledge of the mechanical and physical characteristics of new black locust clones wood already in cultivation via breeding is incomplete. The same applies to climate change effects. The review article recommends that future research investigate the basic characteristics of new cultivars planted in different locations.

Growth Response of Pinus wallichiana to Changing Climate in Temperate Regions of Central Nepal

Climate influences both the structure and function of the forest ecosystem. A dendrochronological study was carried out in temperate forest at Patney Bhanjyang Community Forest of Kavrepalanchok district in Central Nepal to verify and record the impact of climate on radial growth by using the tree cores of Pinus wallichiana. A total of 60 tree cores were collected by using increment borer and annual ring widths were analyzed by using the standard dendrochronological technique. We produced a 74-year-old tree ring width chronology of P. wallichiana from the region and examined the critical climatic factor for radial growth and the temporal trend of Basal Area Increment (BAI). Our results showed that the tree radial growth was not influenced by maximum temperature. However, it was positively correlated with the minimum temperature of the previous year September (0.30) indicating that cool previous September is favorable for radial growth. Similarly, the radial growth of Pine showed a positive correlation with the total rainfall of January (0.33) and March (0.33), showing that enough moisture in the very early growing season contributes positively to radial growth. We found a decline in BAI after 2000 AD until 2005, although BAI was relatively stable despite the decreasing trend of rainfall. We did not find the impact of climatic factor for the decline in BAI. However long-term study of different climatic, ecological and anthropogenic influences are necessary to know more about the growth–climate relationship of P. wallichiana in temperate forests of Nepal.

Effect of Type of Forest Growth Conditions and Climate Elements on the Dynamics of Radial Growth in English Oak (Quercus robur L.) of Early and Late Phenological Forms

The pattern of annual radial growth is influenced by various factors: the local growth conditions, the age structure, and the ecotypes or provenances of trees. A more in-depth approach to the study of specific growth patterns of tree forms is needed to predict the further genesis of forests. This research was carried out on healthy English oak trees of early (EF) and late (LF) phenological forms in Shipov Forest, Voronezh Region. The dendroclimatic analysis was performed on permanent sample plots in wet, dry, and very dry oak stands grown on different soil types. The effect of precipitation on annual ring width was assessed using a one-way ANOVA. The LF showed higher radial growth rates on wet sites than the EF did on dry ones. Their annual radial growth was less stable and more variable compared with the LF. For both phenoforms, the most important radial growth factors are the composite indicators reflecting the ratio of temperature and moisture (Selyaninov’s hydrothermal coefficient and Lang’s rain factor). Generally, the radial growth minima coincided in time on dry and wet sites, and the periods of maximum growth were associated with high-water years.

How Wood Quality Can Be Shaped: Results of 70 Years of Experience

This experiment was conducted in the pine woods of central Europe at a research area established in 1951. The experimental area of 1.35 ha was set up in a 14-year-old pine tree stand, which was divided into lots, and the pruning procedure took place in different variants. Some lots constituted control lots without pruned trees. The trees were pruned in four variants, reducing the living tree crown by 1/4, 1/3, 1/2, and 2/3 of its length. The study’s main aim was to determine the influence of pruning forest trees on the tree tissue. Moreover, the study attempted to answer whether pruning was a significant procedure for wood valorisation, and if yes, then which variant was the optimal one for Scots pine growing on the European plain. The results indicated a significant impact of pruning young pine tree stands on the properties of wood tissue, which differed regarding the adopted pruning variant. Significant differences in the width of annual rings, the size of the particular areas of the annual rings (latewood or earlywood), and the wood density depending on the pruning variant were observed. Furthermore, the results indicated that pruning induced numerous processes, which optimised the physiological and mechanical functions of the tree trunks. The outcome of this optimisation was, among others, the diversification of the vascular and strengthening area of the annual ring as well as the wood density, which was a reaction to reducing a part of the assimilation apparatus. From the technical wood value viewpoint, the optimal pruning variant for pine was between 1/3 to 1/2 of the living crown.

Evaluation of Softwood Timber Quality—A Case Study on Two Silvicultural Systems in Central Germany

Norway spruce (Picea abies (L.) H.Karst) trees planted with high stem densities produce finely branched, solid logs but are vulnerable to extreme weather events, e.g., storms. Over the last decades spruce stands have been planted at lower stand densities, resulting in wider crowns, lower crown bases, and higher stand stability, but this might decrease the quality of coniferous timber due to an increased growing rate and wider annual rings. Therefore, in this case study we investigated the influence of different silvicultural treatments and stand densities on tree morphology and wood properties of 100 spruce trees up to sawn timber as the final product. Tree morphology was assessed using mobile laser scanning. Ring width analysis, wood density measurements, and the four-point bending strength test on visually graded boards were conducted to gain information on wood properties and product quality. In stands thinned from below, higher wood densities were observed due to smaller annual rings compared to stands that were thinned from above at equal annual ring widths. In addition, crown asymmetry and the height-to-diameter ratio were identified as proxies for wood density. Lastly, visually assessed quality differences between the forest stands were discerned on the examined boards.

Forest characteristics, population structure and growth trends of threatened relict Pseudotsuga forrestii in China

Pseudotsuga forrestii is a relict evergreen coniferous tree species in Pinaceae endemic to China. P. forrestii tree numbers have greatly decreased due to deforestation, over-utilization and habitat degradation. Here we clarify P. forrestii community types, structure, species diversity, seedling recruitments and growth trends. We identified four P. forrestii community types: (1) Pseudotsuga forrestii - Quercus guyavifolia - Acer davidii evergreen coniferous and broad-leaved mixed forest; (2) Pseudotsuga forrestii - Pinus yunnanensis - Quercus guyavifolia evergreen coniferous and broad-leaved mixed forest; (3) Pseudotsuga forrestii evergreen coniferous forest; (4) Pseudotsuga forrestii - Abies georgei var. smithii evergreen coniferous forest. P. forrestii forests are characterized by both warm temperate and temperate affinities. Simpson diversity, Pielou evenness, Shannon–Wiener diversity indices ranged from 0.75 to 0.76, 0.74–0.81, and 1.62–1.93, respectively, with no significant differences among the four forest types. The forest stratification was multilayered. The canopy layer was generally 10–25 m tall, with the emergent layer reached 25–42 m. DBH and age structures of P. forrestii showed multimodal distributions. Its maximum age P. forrestii was 570 years with a DBH of 143 cm. The growth of annual ring width of P. forrestii was slow, and generally decreased with age, whereas the basal area at the breast height increased with age. Established seedlings/saplings were mainly found in unstable micro-habitats. Regeneration of P. forrestii depends on moderate natural disturbances. Finally, we provide recommendations for P. forrestii conservation.

Automatic estimation of annual ring profiles in Norway spruce timber boards using optical scanning and deep learning

In softwood species, annual ring width correlates with various timber characteristics, including the density and modulus of elasticity along with bending and tensile strengths. Knowledge of annual ring profiles may contribute to more accurate machine strength grading of sawn timber. This paper proposes a fast and accurate method for automatic estimation of ring profiles along timber boards on the basis of optical scanning. The method utilizes two 1D convolutional neural networks to determine the pith location and detect the surface annual rings at multiple cross-sections along the scanned board. The automatically extracted rings and pith information can then be used to estimate the annual ring profile at each cross-section. The proposed method was validated on a large number of board cross-sections for which the pith locations and radial ring width profiles had been determined manually. The paper also investigates the potential of using the automatically estimated average ring width as an indicating property in machine strength grading of sawn timber. The results indicated that combining the automatically estimated ring width with other prediction variables can improve the accuracy of bending and tensile strength predictions, especially when the grading is based only on information extracted from optical and laser scanning data.

WOOD DENSITY AND ANNUAL RING WIDTH OF PEDUNCULATE OAK FROM STANDS GROWN ON FORMER AGRICULTURAL LAND

The main aim of this study was to determine differences in basic density and average annual ring width of pendulate oak wood collected from trees grown on former agricultural land and on forestland, using a dimensional method. The experiment was carried out in thewestern part of Poland, near to Poznan, which is in the central part of the European range of pedunculate oak. In our study the average basic density was 0.528 g.cm-3, and the value for former agricultural land was lower by 0.026 g.cm-3 than that for forest land. Differences in basic density values between these two land types were statistically significant. The average annual ring width in samples collected from forest land in our study was 2.48 mm, samples from former agricultural land were characterized by wider average annual rings. The results suggest that there are significant differences in quality of wood from former agricultural land and from forest. However, from view of wood quality and applications the difference is not important.