Density Distribution in Wood of European Birch (Betula pendula Roth.)

Abstract

The aim of the presented research is to perform a comprehensive analysis of wood density variability on the longitudinal and transverse cross-section of log trees at the age of 70 to 72 years of Betula pendula Roth. and the creation of density distribution maps. Furthermore, the determination proportion of juvenile and mature wood was done. Wood density was determined with a non-destructive method using an isotopic densimeter. It was found that the wood location, both in cross-section and longitudinal section of the trunk, had a statistically significant effect on the average density of birch wood. The average density of whole logs was significantly higher than the average density at the breast height. On the cross-section, the distribution of average densities determined at the breast height, as well as on 1/4 of the log height, properly depicted the distribution of average densities on the cross-section determined for the whole logs. The geographical direction (north-south) did not have a statistically significant effect on the distribution of average densities on the cross-section of the tested birch logs.In the ring-porous wood species, vessels in juvenile wood are distributed over the entire width of the annual rings as in case diffuse-porous wood species. Another feature that occurs in juvenile wood is the type of perforation in the vessels. In juvenile wood vessels with a simple perforation, ladder perforation was noticed [10]. Mature wood is created by cambium cells when they reach their maximum dimensions. This part of the wooden tissue is characterized by relatively constant cell dimensions and properties [15]. Compared with mature wood, juvenile wood usually stands out by the smaller length of anatomical elements and the proportion of late-wood, which is associated with lower density and worse mechanical properties [6,14,[16][17][18]. Depending on the class and wood species, the strength of juvenile wood constitutes from 50% to 70% of the strength and hardness of mature wood [19].Wood density is one of the most important technological parameters defining its industrial use. The popular species list includes birch wood (Betula) from the birch family (Betulaceae) [20], occurring in almost all of Europe, with the exception of Spain, Greece, and the southern part of Italy, as well as in parts of Asia Minor, Caucasus, and western Siberia. Birch is a pioneer species, rapidly growing and plays an important role in the early stages of primary and secondary succession, as well as in preparing areas for settlement by more demanding species [21]. Moreover, birch belongs to the basic species in plantations of fast-growing forest trees [22]. That wood species is used in industrial applications for the production of plywood, veneers, and furniture, and is a valuable raw material for the pulp, paper, and board industry [3,23]. Due to the significant economic importance of birch wood, many studies on the distribution of density in birch wood have been found in the literature, particularly depending on its age and diam...

Genetic Parameters of Stem and Wood Traits in Full-Sib Silver Birch Families

“…Some comparable studies of juvenile silver birch [10,19,81] had average density values of: 478 kg m −3 for 22-year-old Finnish provenance trials [81], 455 kg m −3 for Latvian plantation-grown birch for ages 11 to 15 years [19], and of 429 kg m −3 for 11-year-old Swedish birch clones [10]. The density values obtained in this report are similar to other studies, yet there is variation within families, and often even within a stem [20,89], which is ignored when average values are used.…”

Effects of Fertilization on Wood Formation in Naturally Regenerated Juvenile Silver Birch in a Norway Spruce Stand in South Sweden

“…It is important to consider the effects of cambial age on stem wood density [52], as the relative fiber wall thickness increases in birch as the tree gets older [27,38]. The trees' average density seemed to increase with increasing cambium age in Figure 2, yet including the random effect of age did not improve the predictive power of ring width or basal area in the mixed models.…”

“…No damaged trees were accepted. The trees were 4-10 years old (at DBH), and all of the wood was therefore considered to be juvenile [51,52]. Two discs were removed from each tree at breast height (1.3 m), as samples from 1.3 m high generally provide a good estimate of the whole tree density value [53].…”

Modeling of radial variations of wood properties in naturally regenerated trees of Betula platyphylla grown in Selenge, Mongolia

“…H. Hara naturally grown in Japan, we recently reported that the boundary determined by radial variations of fiber length was around 1.5 to 4.2 cm from the pith or the 10th to 17th annual ring from the pith [9]. Similar results in terms of radial variations of the density and mechanical properties have been obtained in other Betula species (e.g., B. ermanii Cham., B. maximowicziana Regel, B. pendula Roth, and B. platyphylla), where the region around 5 to 8 cm from the pith has been clearly marked as a low-density and low-strength properties region [16][17][18]. These radial variations of wood properties might be related to the xylem maturation process [9,[11][12][13][14][15]18].…”

“…Similar results in terms of radial variations of the density and mechanical properties have been obtained in other Betula species (e.g., B. ermanii Cham., B. maximowicziana Regel, B. pendula Roth, and B. platyphylla), where the region around 5 to 8 cm from the pith has been clearly marked as a low-density and low-strength properties region [16][17][18]. These radial variations of wood properties might be related to the xylem maturation process [9,[11][12][13][14][15]18]. Therefore, further research is needed to clarify the xylem maturation process for B. platyphylla trees grown in Mongolia to understand the core wood and outer wood properties.…”