Variations In Wood Structure Research Articles

Stem anatomy: development of included and intraxylary phloem in Barleria species (Acanthaceae) occurring in India

Abstract Barleria is known for its different growth forms such as herbs, shrubs, climbers, and rarely trees that show a wide range of variation in wood structure. We investigated the Indian species of Barleria and observed that all are characterized by the presence of included and intraxylary phloem. Included phloem is the strand of sieve elements embedded within the secondary xylem and is believed to perform the same general function as regular phloem (i.e. photosynthate transport). Internal/intraxylary phloem comprises sieve elements that are formed on the periphery of the pith. In the present investigation, a complete study of the stem anatomy of 36 taxa (29 species, one subspecies, two varieties, and four forms) of Indian Barleria species along with two outgroups (Crossandra infundibuliformis and Petalidium barlerioides) was carried out. This is the first comprehensive study on Indian Barleria and could be used for identification of species in the genus. Differences in the outline of stem and pith, the composition of the secondary xylem, variation in the number of the sieve elements within the included phloem islands, septation in fibres, fibre cell wall thickening, and ray types can be used for species delimitation. The present study revealed that depending on species, vessel elements were angular or oval, having a short tail at one end and a long tail on the other end, a short tail on both ends, a long tail on both ends, or without a tail. Among the species investigated, no consistency was observed in the secondary xylem rays. They were mostly uni- to biseriate in some species while in the remaining species they were uni- to multiseriate.

Utilizing wave polarization in microwave characterization of heterogeneous anisotropic materials with application to the wood industry

Abstract This paper presents a novel approach to microwave non-contact, non-destructive testing of wood, investigating additional indicators of wood structure, in particular the significance of wave polarization in transmission measurements. Contribution of wave polarization to wood characterization is studied, considering detection of rapid and gradual variations in wood structure, determination of moisture content and density distribution along the sample, as well as bulk properties detection. A set of microwave sensors in a collinear arrangement was used in two orthogonal linear polarizations. Significant findings are reported, in particular polarization dependence of moisture related attenuation, as well as improved defect detection accuracy when measurements in two orthogonal linear polarizations are considered. In addition, sorting wood samples into categories is considered and the advantages of this approach are presented.

Wood specific gravity and anatomy of branches and roots in 113 Amazonian rainforest tree species across environmental gradients

Wood specific gravity (WSG) is a strong predictor of tree performance across environmental gradients. Yet it remains unclear how anatomical elements linked to different wood functions contribute to variation in WSG in branches and roots across tropical forests. We examined WSG and wood anatomy in white sand, clay terra firme and seasonally flooded forests in French Guiana, spanning broad environmental gradients found throughout Amazonia. We measured 15 traits relating to branches and small woody roots in 113 species representing the 15 most abundant species in each habitat and representative species from seven monophyletic lineages occurring in all habitats. Fiber traits appear to be major determinants of WSG, independent of vessel traits, in branches and roots. Fiber traits and branch and root WSG increased from seasonally flooded species to clay terra firme species and lastly to white sand species. Branch and root wood traits were strongly phylogenetically constrained. Lineages differed in wood design, but exhibited similar variation in wood structure across habitats. We conclude that tropical trees can invest differently in support and transport to respond to environmental conditions. Wind disturbance and drought stress represent significant filters driving tree distribution of Amazonian forests; hence we suggest that biophysical explanations should receive more attention.

Variation throughout the tree stem in the physical-mechanical properties of the wood

This study analyses the variation of main physical-mechanical properties of wood along the longitudinal and radial directions of the tree for Abies alba Mill. growing in the Spanish Pyrenees. Smallclear specimens were used to study the properties of volumetric shrinkage (VS), density (ρ), hardness (H), bending strength (MOR), modulus of elasticity (MOE), maximum compressive strength parallel to the grain (MCS) and impact strength (K). Several models of properties variation in the longitudinal and radial directions were analyzed. Main trends of variation of properties throughout the tree stem were identified although none of them could be fitted to predictive statistical models. Along the longitudinal direction, the properties studied followed a downward trend from the base to the crown, which was not significant in all cases, indicating that no differences in quality existed. Throughout the radial directionthe trend is upward for the first 40-50 growth rings, after which it slopes downwards, more gently at first until rings 70-75 and then more steeply. This behaviour is related to variation in wood structure from the pith to the bark, depending on whether the wood is juvenile, sapwood or heartwood, and to wood maturityand microfibril angle. Authors encourage carrying further studies on other populations of A. alba in the Spanish Pyrenees to check if the trends found in this study apply to other provenances.

Radial Gradients in Wood Specific Gravity, Water and Gas Content in Trees of a Mexican Tropical Rain Forest

AbstractCell walls, water, and gas that have mechanical and physiological functions in wood, and wood specific gravity (WSG) is related to demographic traits. To understand variation in wood structure and function, we analyzed radial changes in WSG, in the gas and the water fractions from trees growing in four different habitats in a southern Mexican rain forest. Mean WSG was 0.55 ± 0.16, slightly lower than reported for other tropical forests. In 27 species, WSG decreased and in two species, it increased from pith to bark with a strong (r2 = 0.65) negative correlation between WSG in the center of the tree and the radial WSG gradient. Habitat had some effect on mean WSG and trees growing on karst had significantly higher WSG than the same species growing on alluvial soil. The cell wall, water, and gas fractions accounted for 35 percent (range: 16–50), 42 percent (28–65), and 23 percent (2–56), respectively, of wood volume, with a negative correlation between the gas and the cell wall and between the gas and the water fractions, but not between the cell wall and water fractions. Radially increasing WSG is advantageous for pioneer trees with fast initial growth. We found that the water displacement method may result in biased WSG estimates. To increase the accuracy of WSG data, we suggest to measure sample volume geometrically using a constant diameter (that of the borer tip), to include radial variation in WSG, and to consider for possible site effects on species‐specific WSG.

Drought alters timing, quantity, and quality of wood formation in Scots pine

Drought has been frequently discussed as a trigger for forest decline. Today, large-scale Scots pine decline is observed in many dry inner-Alpine valleys, with drought discussed as the main causative factor. This study aimed to analyse the impact of drought on wood formation and wood structure. To study tree growth under contrasting water supply, an irrigation experiment was installed in a mature Scots pine (Pinus sylvestris L.) forest at a xeric site in a dry inner-Alpine valley. Inter- and intra-annual radial increments as well as intra-annual variations in wood structure of pine trees were studied. It was found that non-irrigated trees had a noticeably shorter period of wood formation and showed a significantly lower increment. The water conduction cells were significantly enlarged and had significantly thinner cell walls compared with irrigated trees. It is concluded that pine trees under drought stress build a more effective water-conducting system (larger tracheids) at the cost of a probably higher vulnerability to cavitation (larger tracheids with thinner cell walls) but without losing their capability to recover. The significant shortening of the growth period in control trees indicated that the period where wood formation actually takes place can be much shorter under drought than the 'potential' period, meaning the phenological growth period.

Drought alters timing, quantity, and quality of wood formation in Scots pine

Drought has been frequently discussed as a trigger for forest decline. Today, large-scale Scots pine decline is observed in many dry inner-Alpine valleys, with drought discussed as the main causative factor. This study aimed to analyse the impact of drought on wood formation and wood structure. To study tree growth under contrasting water supply, an irrigation experiment was installed in a mature Scots pine (Pinus sylvestris L.) forest at a xeric site in a dry inner-Alpine valley. Inter- and intra-annual radial increments as well as intra-annual variations in wood structure of pine trees were studied. It was found that non-irrigated trees had a noticeably shorter period of wood formation and showed a significantly lower increment. The water conduction cells were significantly enlarged and had significantly thinner cell walls compared with irrigated trees. It is concluded that pine trees under drought stress build a more effective water-conducting system (larger tracheids) at the cost of a probably higher vulnerability to cavitation (larger tracheids with thinner cell walls) but without losing their capability to recover. The significant shortening of the growth period in control trees indicated that the period where wood formation actually takes place can be much shorter under drought than the 'potential' period, meaning the phenological growth period.

Esau's Plant anatomy: meristems, cells, and tissues of the plant body: their structure, function, and development

Preface. Acknowledgments. General References. Chapter 1. Structure and Development of the Plant Body-An Overview. Chapter 2. The Protoplast: Plasma Membrane, Nucleus, and Cytoplasmic Organelles. Chapter 3. The Protoplast: Endomembrane System, Secretory Pathways, Cytoskeleton, and Stored Compounds. Chapter 4. Cell Wall . Chapter 5. Meristems and Differentiation. Chapter 6. Apical Meristems. Chapter 7. Parenchyma and Collenchyma. Chapter 8. Sclerenchyma. Chapter 9. Epidermis. Chapter 10. Xylem: Cell Types and Developmental Aspects. Chapter 11. Xylem: Secondary Xylem and Variations in Wood Structure. Chapter 12. Vascular Cambium. Chapter 13. Phloem: Cell Types and Developmental Aspects. Chapter 14. Phloem: Secondary Phloem and Variations in Its Structure. Chapter 15. Periderm. Chapter 16. External Secretory Structures. Chapter 17. Internal Secretory Structures. Addendum: Other Pertinent References Not Cited in the Text. Glossary. Author Index. Subject Index.

Variation in wood structure of eastern larch defoliated by the larch sawfly in subarctic Quebec, Canada

We studied the wood structure of eastern larch (Larixlaricina (Du Roi) K. Koch) affected by a larch sawfly (Pristiphoraerichsonii (Htg.)) infestation that occurred in 1939 in the Lac à l'Eau-Claire and Rivière-aux-Mélèzes areas, subarctic Quebec. The objective was to document variation in wood characteristics in relation to defoliation at three study sites. Lumen diameter of tracheids and cell wall thickness were measured from thin sections representing the 1931–1955 period. Significant changes in the wood structure of larch was noticed only at the Atkinson Island site, where the radial growth pattern was typical of the insect activity. A light ring was formed the 1st year of the infestation (1939). During the 2nd year (1940), the size of tracheids (lumen) decreased abruptly along with radial growth, while the proportion of latewood increased. The variation in wood anatomy among the three study sites paralleled that in radial growth. Wood structure appears to be a good indicator of the end of an infestation.

Variation in Wood Anatomy of White Spruce in Response to Dune Activity

Variation in the wood anatomy of a white spruce (Picea glauca [Moench] Voss) growing in the surroundings of an active dune and subjected to burial by eolian sands and subsequent exposure of its main stem under wind action was studied. Maximum thickness of eolian sediments accumulated above the root collar was 3.4 m, and the stem was subsequently exposed to a depth of 1.86 m along the bole. The size of cell cavities was processed using a digitizing video camera mounted on an optical microscope for image analysis. Our results indicate that the mean increase in size of tracheids for all levels was close to 50%. The increase in tracheid size and decrease of radial growth in response to stem burial were not synchronous, the change being more rapid in cell size than in radial growth. The frequency distribution of tracheid sizes at the time of maximum sand deposition showed a general trend towards larger tracheids from lower to upper sections of the tree stem, and it differed at all levels from that of a reference tree. Because of the spontaneous response in wood anatomy of affected trees, the variation in wood structure can become a useful temporal marker, especially in sites affected by slow environmental changes.

Population variation in wood structure of white fir

Wood X-ray densitometry (inter- and intra-ring wood density, ring width) and measurements of tracheid length were used to evaluate wood structural variability in 93 trees from 33 populations of white fir (Abiesconcolor (Gord. et Glend.) Lindl.). Individuals from populations representing the geographic range of the species had been growing for 24 years in a plantation near Placerville, California. Growth ring widths showed a clinal increase from northern Oregon to southern Californian populations, due mostly to variations in width of the earlywood. Rates of change from pith to bark in tracheid lengths and earlywood density decreased from northern Oregon to southern California, with the highest rates of change being among Utah populations. Slower rates of change in tracheid length and wood density would contribute to more uniform wood structure in these southern populations. Multivariate analyses confirmed the separation of regional groups within white fir. Results indicated that there is a differentiation between northern and southern Californian white fir, consistent with the former being ascribed to A. concolor var. lowiana and the latter to A. concolor var. concolor. Arizonan populations were grouped with southern Californian white fir.

Lateral cutting force during machining of wood due to momentary disturbances in the wood structure and degree of wear of the cutting tool

The paper presents a study of the effect of momentary disturbances due to variations in wood structure on the lateral cutting force. Density, shape and fibre-direction of the disturbances, and the degree of wear of the cutting tool are taken into consideration. The paper shows that high density gradients result in high lateral forces. The highest momentary lateral force noted has a value of approximately 40 N. The geometrical shape of the cutting tool in terms of degree of wear has a big impact on the lateral force. The work indicates a potential to increase the cutting performance by a more accurate supervision of the condition of the cutting tools.

The use of gray scale images when evaluating disturbances in cutting force due to changes in wood structure and tool shape

A method is presented for studying the effect of momentary disturbances due to variations in wood structure on the cutting force near the cutting edge. Force and density measurements are converted to a gray scale image. This method is very effective as regards the evaluation of experimental tests.

Variation in wood structure of white fir along an elevational transect

Several wood structural characteristics were measured in 15-year-old Abiesconcolor (white fir) from four populations along an elevational transect in the central Sierra Nevada region. The trees had been growing in a plantation near Placerville, California. Growth rings were narrower at breast height, latewood percentage tended to be greater, and tracheids were shorter in trees from higher elevation populations. Proportion of family variance components was greater than population for specific gravity and spiral grain angle. The characteristics that showed greatest population components of variation would be largely determined by durations and rates of shoot and radial growth. Presumably, length of the growing season would exert stronger selection pressure on these variables than on other characteristics of wood structure.

ALTERNATIVES TO THE ASSESSMENT OF EARLYWOOD AND LATEWOOD IN DICOTYLEDONOUS TREES: A STUDY OF STRUCTURAL VARIATION IN GROWTH RINGS OF APPLE (MALUS PUMILA MILL.)

SummarySeveral indices describing the variation in wood structure within growth rings of dicotyledon trees were examined in apple (Malus pumila Mill.) scions grafted on to four rootstocks of different vigour. The cross‐sectional dimensions of 9600 fibres and 7200 vessel elements were measured in each rootstock and scion combination. Indices incorporating lumen width and wall thickness of fibres varied more or less linearly across growth rings, so that assessment of latewood could be made only by selecting some arbitrary limit, which may not be suitable for all rootstocks. The patterns of variation in vessel lumen area within growth rings varied markedly between rootstocks, and gave no clear indication of the point in the ring at which latewood formation might begin. A less extensive study of the distribution of tissues in the xylem at five positions across a growth ring showed that there tended to be a prominent reduction in the proportion of vessels, and an increase in the proportion of fibres between 10 and 30% of the distance across the ring. It was concluded that the concept of earlywood and latewood is not helpful to fundamental studies of wood structure and formation, and that in industry, measurement of relevant properties, such as the density of wood or fibres, may be made as easily as the determination of proportions of earlywood and latewood, however these wood zones be defined.

Variation in wood structure in relation to wood quality

Variation in wood structure in relation to wood quality

Anatomy of Seed Plants

INTRODUCTION. Internal Organization of the Plant Body. Summary of Types of Cells and Tissues. General References. DEVELOPMENT OF THE SEED PLANT. The Embryo. From embryo to the Adult Plant. Apical Meristems and Their Derivatives. Differentiation, Specialization, and Morphogenesis. References. THE CELL. Cytoplasm. Nucleus. Plastids. Mitochondria. Microbodies. Vacuoles. Paramural Bodies. Ribosomes. Dictyosomes. Endoplasmic Reticulum. Lipid Globules. Microtubules. Ergastic Substances. References. CELL WALL. Macromolecular Components and Their Organization in the Wall. Cell Wall Layers. Intercellular Spaces. Pits, Primary Pit--Fields, and Plasmodesmata. Origin of Cell Wall During Cell Division. Growth of Cell Wall. References. PARENCHYMA AND COLLENCHYMA. Parenchyma. Collenchyma. References. SCLERENCHYMA. Sclereids. Fibers. Development of Sclereids and Fibers. References. EPIDERMIS. Composition. Developmental Aspects. Cell Wall. Stomata. Trichomes. References. XYLEM: GENERAL STRUCTURE AND CELL TYPES. Gross Structure of Secondary Xylem. Cell Types in the Secondary Xylem. Primary Xylem. Differentiation of Tracheary Elements. References. XYLEM: VARIATION IN WOOD STRUCTURE. Conifer Wood. Dicotyledon Wood. Some Factors in Development of Secondary Xylem. Identification of Wood. References. VASCULAR CAMBIUM. Organization of Cambium. Developmental Changes in the Initial Layer. Patterns and Causal Relations in Cambial Activity. References. PHLOEM. Cell Types. Primary Phloem. Secondary Phloem. References. PERIDERM. Structure of Periderm and Related Tissues. Development of Periderm. Outer Aspect of Bark in Relation to Structure. Lenticels. References. SECRETORY STRUCTURES. External Secretory Structures. Internal Secretory Structures. References. THE ROOT: PRIMARY STATE OF GROWTH. Types of Roots. Primary Structure. Development. References. THE ROOT: SECONDARY STATE OF GROWTH AND ADVENTITIOUS ROOTS. Common Types of Secondary Growth. Variations in Secondary Growths. Physiologic Aspects of Secondary Growth in Roots. Adventitious Roots. References. THE STEM: PRIMARY STATE OF GROWTH. External Morphology. Primary Structure. Development. References. THE STEM: SECONDARY GROWTH AND STRUCTURAL TYPES. Secondary Growth. Types of Stems. References. THE LEAF: BASIC STRUCTURE AND DEVELOPMENT. Morphology. Histology of Angiosperm Leaf. Development. Abscission. References. THE LEAF: VARIATIONS IN STRUCTURE. Leaf Structure and Environment. Dicotyledon Leaves. Monocotyledon Leaves. Gymnosperm Leaves. References. THE FLOWER: STRUCTURE AND DEVELOPMENT. Concept. Structure. Development. References. THE FLOWER: REPRODUCTIVE CYCLE. Microsporogenesis. Pollen. Male Gametophyte. Megasporogenesis. Female Gametophyte. Fertilization. References. THE FRUIT. Concept and Classification. The Fruit Wall. Fruit Types. Fruit Growths. Fruit Abscission. References. THE SEED. Concept and Morphology. Seed Development. Seed Coat. Nutrient Storage Tissues. References. EMBRYO AND SEEDLING. Mature Embryo. Development of Embryo. Classification of Embryos. Seedling. References. Glossary. Index.

Variations in Wood Structure

Variations in Wood Structure