The relationship between the spatial organization of different cell types, of the xylem rays, and of the tree rings and the frequencies in vibrating softwoods and hardwoods was studied under controlled conditions. In total, the frequencies in 1007 standardized vibrating plates from 16 softwoods and 74 hardwoods were analysed using high resolution laser sensors (accuracy ± 0.02 μm, sampling frequency 30 kHz) for vibration measurements. Overlapping frequencies within the frequency spectra were identified by means of Fast Fourier Transformation analysis. With regard to the number of distinct frequencies within the spectra, four different vibration types were identified: type 1–one dominant frequency within the frequency spectra; type 2-two dominant frequencies within the frequency spectra; type 3-three dominant frequencies within the frequency spectra; type 4-no dominant frequencies within the frequency spectra. The presence of distinct frequencies was correlated with a highly organized spatial arrangement of tracheids in softwoods, with a storied arrangement of the xylem rays in hardwoods, and with low variation in tree-ring width in both softwoods and hardwoods. The grid size for repetition in these xylem structures influenced the frequencies of the vibrating wood in absolute numbers. The results indicate that the analysis of the anatomical structure of the wood can contribute to the grading of timber for its vibration characteristics, which is of special interest for the selection of resonance wood for musical instruments.
Xylem vessels interconnect to form the vessel network that is responsible for long-distance water transport through the plant. As plants dehydrate, the water column within vessels cavitates and gas emboli form, which block transport through embolized vessels. The impact of vessel blockages on transport through the xylem tissue depends upon vessel size and the arrangement and connections between vessels in the network. We examined if there was a correlation between vessel length and diameter within poplar stem xylem tissue using both silicone-injection and analysis of tissue volumes scanned using high-resolution computed tomography (microCT). We then used microCT to scan intact stems sampled over varying water potentials to examine if larger vessels, which would have the greatest impact on hydraulic transport, were more vulnerable to cavitation and embolism than smaller vessels. Within the xylem tissue, larger diameter vessels tended to be longer than narrow diameter vessels. Vessel size distributions indicated that most vessels were narrow and short, with fewer large vessels. Larger volume vessels tended to embolize at higher water potentials and the mean vessel volume of embolized vessels declined as water potentials declined. Hydraulic transport through the xylem tissue was near zero when about 40% of the vessels within the xylem tissue volume were embolized, suggesting important vessel network effects occur as water moves through a three-dimensional (3D) tissue. The structure of the vessel network is important in understanding the impact of emboli within vessels on the overall hydraulic function of xylem tissue.
Agarwoods such as Aquilaria spp. and Gyrinops spp. (Thymelaeaceae) produce interxylary phloem in their secondary xylem and intraxylary phloem at the periphery of the pith, facing the primary xylem. We studied young shoots of Aquilaria sinensis and characterized the development of its intraxylary phloem. It was initiated by the division of parenchyma cells localized in the outer parts of the ground meristem immediately following the maturation of first-formed primary xylem. Its nascent sieve plates bore donut-like structures, the individual pores of which were so small (less than 0.1 μm) that they were hardly visible under FE-SEM. Intraxylary phloem developed into mature tissue by means of the division and proliferation of parenchyma cells. During the shoots’ active growth period, the sieve pore sizes were 0.1–0.5 μm, with tubular elements passing through them. In the maturation stage, large clusters of sieve tubes continued to be differentiated in the intraxylary phloem. In the partial senescence stage observed in a three-centimeter-diameter branch, intraxylary phloem cells in the adaxial part became crushed, and sieve plates had pores over 1–2 μm in diameter without any callose deposition. Before and after the differentiation of interxylary phloem in the first and second internodes, callose staining detected more than twice as many sieve tubes in intraxylary phloem than in external phloem. However, after differentiation of interxylary phloem in the eleventh internode, more sieve tubes were found in interxylary phloem than in intraxylary and external phloem. This suggests that prior to the initiation of interxylary phloem intraxylary phloem acts as the principal phloem. After its differentiation, however, interxylary phloem takes over the role of principal phloem. Interxylary phloem thus acts as the predominant phloem in the translocation of photosynthates in Aquilaria sinensis.
Stryphnodendron Mart. is a widespread genus in the Neotropics and its species are widely used for their timber, in popular medicine, and for tanning. The similarities in their external morphology make species identification difficult in this genus. This study describes and compares the wood anatomy of the seven species of Stryphnodendron most frequently found in Brazilian forest remnants, in order to identify which anatomical features can be used in their segregation. From seven species 31 samples of Stryphnodendron were studied. Principal Component Analysis was used to evaluate wood anatomical characters. The species were separated into two main groups, congruent with the division into multifoliolate and paucifoliolate species, due to the presence of diffuse, lozenge-aliform and confluent axial parenchyma. In the multifoliolate group, although two subgroups were formed due to ray width in number of cells, none of the species were individualised, which corroborates previous findings of high morphological and anatomical similarities of the multifoliolate species.
Pterocarpus santalinus, listed in CITES Appendix II, is an endangered timber species as a result of illegal harvesting due to its high value and commercial demand. The growing demand for P. santalinus and timbers with the morphologically similar Pterocarpus tinctorius has resulted in confusion as well as identification problems. Therefore, it is of vital importance to explore reliable ways to accurately discriminate between P. santalinus and P. tinctorius. In this study, the method of direct analysis in real time and fourier transform ion cyclotron resonance mass spectrometry (DART-FTICR-MS), combined with multivariate statistical analysis, was used to extract chemical information from xylarium wood specimens and to explore the feasibility of distinguishing these two species. Significant differences were observed in their DART-FTICR-MS spectra. Orthogonal partial least square-discriminant analysis (OPLS-DA) showed the highest prediction, with an accuracy of 100%. These findings demonstrate the feasibility of authenticating wood types using DART-FTICR-MS coupled with multivariate statistical analysis.
Hand spinning has become increasingly popular as a recovery of the traditional techniques of natural fibre processing and cultural heritage protection. Modern spinning wheels are usually made of easily available wood species, particularly hardwoods, and one spinning wheel usually consists of one or two species. However, the wood species that were used for the individual parts of old spinning wheels in Central Europe are still unknown. To improve our understanding of traditional craftsmen and their skills, we investigated old spinning wheels that originated from Central Europe in the 19th and the 20th century. In this study, we present a collection of 643 samples from 54 artefacts representing the region between the European Alps and the Western Carpathians. Spinning wheels were usually made of 3 to 5 wood species, and the species selection varied among regions. Generally, high wood density (> 600 kg.m−3) species prevailed in Austria and Western Slovakia, but lower wood density (< 600 kg.m−3) species were preferred in the south-eastern Czech Republic. Easily workable species were used for the production of the spinning wheels, primarily Tilia, Fagus sylvatica, Picea abies, and Acer. In addition to these species, a high proportion of fruit-bearing trees and three shrubs were identified. Wood anatomy, as an important scientific method, contributed to understanding the reasons for species selection and the suitability of their properties which will enable the conservation of sustainable folk traditions and crafts, as well as the knowledge of traditional craftsmen.
Peatland ecosystems are an important archive of paleoclimatic information. Within this context, tree-ring data from trees growing in such ecosystems are extremely valuable resources, and subfossil trees from peat bogs have been widely employed in dendroclimatological studies. However, there are still gaps in our understanding of the relationships among tree growth, peatland hydrology and climate factors. Here, we summarize the principal studies on living peatland trees, with a particular focus on their use as a source of information on past climatic conditions. We discuss the main factors influencing tree growth in this environment, whether it is the local hydrological cycle or climate. We put a particular focus on the reliability of the climate signal recorded by living peatland trees, comparing it with that found in subfossil trees. Finally, we discuss the relevance of quantitative wood anatomy in the context of peatland ecosystems research.
Covariation amongst wood traits along the stem axis is important to maintain hydraulic integrity ensuring sufficient sap flow to the canopy. Here, we test how wood traits (co)vary along the trunk and whether two seasonally dry Brazilian habitats (cerrado and caatinga) influence this variation in two co-occurring species, Tocoyena formosa (Rubiaceae) and Tabebuia aurea (Bignoniaceae). The samples were collected at five heights along the main trunk of three individuals per species in both sites. We used light, scanning and transmission electron microscopy to observe the wood traits. Out of 13 wood traits, nine show relationships with sampling height: eight traits predict height in T. formosa and five in T. aurea. Contrastingly, only three traits show differences between sites and only for T. formosa. The intratrunk wood variation is reflected by the hydraulically weighted vessel diameter showing a curvilinear relationship, disagreeing with the prediction of a continuous vessel widening from tip to base. In both species, the largest vessels are linked to the thinnest intervessel pit membranes. Wood density increases basipetally for both species, being site-dependent and correlated with vessel traits in T. formosa, and site-independent and determined by fiber wall thickness in T. aurea. Furthermore, the functional role of rays was found to be different for each species, and may be related to the marked difference in ray composition. In conclusion, both species show a unique adaptation to deal with height-related constraints using species-specific co-variation amongst wood traits, while site does not contribute much to the wood variation.
Ongoing climate change is expected to alter forests by affecting forest productivity, with implications for the ecological functions of these systems. Despite its great dendrochronological potential, little research has been conducted into the use of wood density as a proxy for determining sensitivity to climate variability in Mexico. The response of Abies durangensis Martínez, in terms of wood density and growth ring width, to monthly climatic values (mean temperature, accumulated precipitation and the drought index SPEI) was analyzed through correlation analysis. Abies durangensis presents a high response, in terms of radial growth, to climatic conditions. Tree-ring widths are more sensitive to hydroclimatic variables, whereas wood density values are more sensitive to temperature. In particular, mean (MeanD) and minimum (MND) wood density values are more sensitive to climate than maximum (MXD). We found very marked spatial variations that indicate that A. durangensis responds differently to drought conditions depending on the indices of density.