Wood science covers in particular the areas of the formation and composition as well as the chemical, biological and physical-mechanical properties of wood. First comprehensive studies have already ...been published in the last century. Detailed knowledge of wood is required for the processing of wood, the production of wood-based materials, and the utilization of wood and wood-based materials as buildings and various other products such as furniture. This review gives a brief overview on the progress in wood chemistry, wood biology (including photosynthesis and biodeterioration), and physical-mechanical properties of wood and wood-based materials. These fundamentals are also essential for understanding technological processes and product development.
Prof. Dr. Dieter Eckstein (1939-2021) was a leading scientist, teacher, mentor, leader, promoter and motivator in the field of dendrochronology and wood biology. After graduating in wood science and ...receiving a PhD in dendrochronology, he was professor of wood biology at the University of Hamburg. From 1995-2004, he was Director of the Department of Wood Biology, University of Hamburg, and of the Institute of Wood Biology and Wood Protection at the Federal Research Centre for Forestry and Forest Products in Hamburg, Germany. His work had a decisive influence on the development of wood anatomy, wood biology and dendrochronology and his laboratory was a reference point for dendrochronology worldwide. He supported dendrochronologists throughout Europe and around the world in their pioneering work to establish dendrochronology laboratories and develop dendrochronology in numerous countries, including Slovenia.
Prof. Dr. Dieter Eckstein (1939 - 2021) significantly influenced the global development of dendrochronology and the underlying science of wood biology. Eckstein’s research areas included ...dendroclimatology, xylogenesis, ecophysiology, and quantitative wood anatomy. His personal and collaborative work continues to improve our understanding of both the natural environment and human cultural development. The techniques he developed and championed resolved long-standing difficulties in the application of tree-ring science to understand both natural processes and human effects on tree and forest development. As importantly, he nurtured and promoted both the careers and the lives of many fellow scholars and students around the world. Here we present a systematic bibliography of more than 280 publications that illustrates the development of tree-ring research in Europe and elsewhere throughout the almost 50 years of Eckstein’s career. Throughout his scientific career, Eckstein pioneered, developed, and promoted research opportunities with his students and co-workers at the University of Hamburg and beyond. His greatest legacy for his students and colleagues, and which we are challenged to continue, is to continue to build the international spirit of a "dendrofamily".
Background
Vessel‐associated cells (VACs) are highly specialized, living parenchyma cells that are in direct contact with water‐conducting, dead vessels. The contact may be sparse or in large tight ...groups of parenchyma that completely surrounds vessels. VACs differ from vessel distant parenchyma in physiology, anatomy, and function and have half‐bordered pits at the vessel‐parenchyma juncture. The distinct anatomy of VACs is related to the exchange of substances to and from the water‐transport system, with the cells long thought to be involved in water transport in woody angiosperms, but where direct experimental evidence is lacking.
Scope
This review focuses on our current knowledge of VACs regarding anatomy and function, including hydraulic capacitance, storage of nonstructural carbohydrates, symplastic and apoplastic interactions, defense against pathogens and frost, osmoregulation, and the novel hypothesis of surfactant production. Based on microscopy, we visually represent how VACs vary in dimensions and general appearance between species, with special attention to the protoplast, amorphous layer, and the vessel‐parenchyma pit membrane.
Conclusions
An understanding of the relationship between VACs and vessels is crucial to tackling questions related to how water is transported over long distances in xylem, as well as defense against pathogens. New avenues of research show how parenchyma‐vessel contact is related to vessel diameter and a new hypothesis may explain how surfactants arising from VAC can allow water to travel under negative pressure. We also reinforce the message of connectivity between VAC and other cells between xylem and phloem.
Functional lifespans of xylem vessels Jacobsen, Anna L.; Valdovinos-Ayala, Jessica; Pratt, R. Brandon
American journal of botany,
02/2018, Volume:
105, Issue:
2
Journal Article
Peer reviewed
Open access
Premise of the Study
Xylem vessels transition through different stages during their functional lifespan, including expansion and development of vessel elements, transition to vessel hydraulic ...functionality, and eventual transition to post‐functionality. We used information on vessel development and function to develop a model of vessel lifespan for woody plants.
Methods
We examined vessel functional lifespan using repeated anatomical sampling throughout the growing season, combined with active‐xylem staining to evaluate vessel hydraulic transport functionality. These data were combined with a literature review. The transitions between vessel functional lifespans for several species are illustrated, including grapevine (Vitis vinifera L., Vitaceae), English oak (Quercus robur L., Fagaceae), American chestnut Castanea dentata (Marshall) Borkh.; Fagaceae, and several arid and semi‐arid shrub species.
Key Results
In intact woody plants, development and maturation of vessel elements may be gradual. Once hydraulically functional, vessel elements connect to form a vessel network that is responsible for bulk hydraulic flow through the xylem. Vessels become nonfunctional due to the formation of gas emboli. In some species and under some conditions, vessel functionality of embolized conduits may be restored through refilling. Blockages, such as tyloses, gels, or gums, indicate permanent losses in hydraulic functional capacity; however, there may be some interesting exceptions to permanent loss of functionality for gel‐based blockages.
Conclusions
The gradual development and maturation of vessel elements in woody plants, variation in the onset of functionality between different populations of vessels throughout the growing season, and differences in the timing of vessel transitions to post‐functionality are important aspects of plant hydraulic function.
From the sap’s perspective Schenk, H. Jochen; Espino, Susana; Rich-Cavazos, Sarah M. ...
American journal of botany,
02/2018, Volume:
105, Issue:
2
Journal Article
Peer reviewed
Open access
Premise of the Study
Xylem sap in angiosperms moves under negative pressure in conduits and cell wall pores that are nanometers to micrometers in diameter, so sap is always very close to surfaces. ...Surfaces matter for water transport because hydrophobic ones favor nucleation of bubbles, and surface chemistry can have strong effects on flow. Vessel walls contain cellulose, hemicellulose, lignin, pectins, proteins, and possibly lipids, but what is the nature of the inner, lumen‐facing surface that is in contact with sap?
Methods
Vessel lumen surfaces of five angiosperms from different lineages were examined via transmission electron microscopy and confocal and fluorescence microscopy, using fluorophores and autofluorescence to detect cell wall components. Elemental composition was studied by energy‐dispersive X‐ray spectroscopy, and treatments with phospholipase C (PLC) were used to test for phospholipids.
Key Results
Vessel surfaces consisted mainly of lignin, with strong cellulose signals confined to pit membranes. Proteins were found mainly in inter‐vessel pits and pectins only on outer rims of pit membranes and in vessel‐parenchyma pits. Continuous layers of lipids were detected on most vessel surfaces and on most pit membranes and were shown by PLC treatment to consist at least partly of phospholipids.
Conclusions
Vessel surfaces appear to be wettable because lignin is not strongly hydrophobic and a coating with amphiphilic lipids would render any surface hydrophilic. New questions arise about these lipids and their possible origins from living xylem cells, especially about their effects on surface tension, surface bubble nucleation, and pit membrane function.
Premise of the Study
Dimensions and spatial distribution of vessels are critically important features of woody stems, allowing for adaptation to different environments through their effects on ...hydraulic efficiency and vulnerability to embolism. Although our understanding of vessel development is poor, basipetal transport of auxin through the cambial zone may play an important role.
Methods
Stems of Populus tremula ×alba were treated with the auxin transport inhibitor N‐1‐naphthylphthalamic acid (NPA) in a longitudinal strip along the length of the lower stem. Vessel lumen diameter, circularity, and length; xylem growth; tension wood area; and hydraulic conductivity before and after a high pressure flush were determined on both NPA‐treated and control plants.
Key Results
NPA‐treated stems formed aberrant vessels that were short, small in diameter, highly clustered, and angular in cross section, whereas xylem formed on the untreated side of the stem contained typical vessels that were similar to those of controls. NPA‐treated stems had reduced specific conductivity relative to controls, but this difference was eliminated by the high‐pressure flush. The control treatment (lanolin + dimethyl sulfoxide) reduced xylem growth and increased tension wood formation, but never produced the aberrant vessel patterning seen in NPA‐treated stems.
Conclusions
These results are consistent with a model of vessel development in which basipetal polar auxin transport through the xylem‐side cambial derivatives is required for proper expansion and patterning of vessels and demonstrate that reduced auxin transport can produce stems with altered stem hydraulic properties.
Premise of the Study
Recent research has highlighted the importance of living tissue in wood. Polyploidization can impact amounts and arrangements of living cells in wood, potentially leading to ...increased drought tolerance. Tetraploid variants were created from the apple cultivar Malus ×domestica ‘Gala’ (Gala‐4x), and their vulnerability to drought‐induced cavitation and their hydraulic capacitance were compared to those of their diploid predecessors (Gala‐2x). Assuming a positive correlation between polyploidy and drought tolerance, we hypothesized lower vulnerability and higher capacitance for the tetraploid.
Methods
Vulnerability to drought‐induced cavitation and the hydraulic capacitance were quantified through acoustic emission and continuous weighing of shoots during a bench‐top dehydration experiment. To underpin the hydraulic trait results, anatomical variables such as vessel area, conduit diameter, cell wall reinforcement, and ray and vessel‐associated parenchyma were measured.
Key Results
Vulnerability to drought‐induced cavitation was intrinsically equal for both ploidy variants, but Gala‐4x proved to be more vulnerable than Gala‐2x during the early phase of desiccation as was indicated by its significantly lower air entry value. Higher change in water content of the leafy shoot, higher amount of parenchyma, and larger vessel area and size resulted in a significantly higher hydraulic capacitance and efficiency for Gala‐4x compared to Gala‐2x.
Conclusions
Both ploidy variants were typified as highly sensitive to drought‐induced cavitation, with no significant difference in their overall drought vulnerability. But, when water deficit is short and moderate, Gala‐4x may delay a drought‐induced decrease in performance by trading hydraulic safety for increased release of capacitively stored water from living tissue.
The paper discusses the research results on the influence of forest types on the wood specific gravity of Scots pine as an integral indicator of wood quality. For the study, pine stands were selected ...in the forest conditions of the Precarpathian region (Ukraine). In the forest type of wet pine broadleaves biotope, wood density at the moisture content of 8% varied in the range from 356 to 735 kg∙m-3 with an average value of 511 kg∙m-3 and exceeded the similar indicator in fresh pine broadleaves biotope by 11%. A linear relationship between the wood specific gravity and the number of annual tree rings in 1 cm was established, which was described by the equation of the first level. A multiple comparison of the obtained research results allowed to distinguish four groups of wood samples in relation to wood density and the number of growth rings in 1 cm. The average value of the wood density for the first group of samples with the number of annual rings less than 5 pcs.∙cm-1 is equal to 385 kg∙m-3, and for the fourth with the number of annual rings more than 16 pcs.∙cm-1 - 601 kg∙m-3. The last one was characterized by the largest range of changes of the wood density, which varied from 445 to 735 kg∙m-3. The obtained results are of practical importance for the selection of stemwood for its desired purpose.
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