There is a need to determine stiffness at an early age, to help capture genetic breeding opportunities for better structural lumber. The current study investigates the possibility of selecting Pinus radiata clones with high modulus of elasticity (MOE). Various ways of measuring MOE are examined: traditional static bending, axial compression of bolts, existing sonic methods, as well as a tool specifically configured for resonance on short bolts. Wood characteristics and microfibril angle are measured on discs taken from each tree. Results show a good correlation between acoustic and static measurements of modulus of elasticity. Moreover, the selected seven radiata clones differ in stiffness by a factor of two, and much of this variation seems to relate to differences in microfibril angle. The results validate the assumption that there is potential to improve wood stiffness of radiata pine genetically. This work does not offer definitive solutions but explores a number of approaches that could be utilised as a selection tool in tree breeding for better product performance of radiata lumber. Here, development of methods based on acoustics is shown to assist in the necessary mass screening of clones for stiffness properties. Methoden zum Messen der Steifigkeit von jungen BäumenFür die genetische Züchtung besteht ein Bedarf, schon zu einem frühen Zeitpunkt die Steifigkeit der Bäume zu bestimmen, um höherwertigeres Schnittholz zu erzielen. Die gegenwärtige Untersuchung prüft die Möglichkeit Klone von Pinus radiata mit hohen MOE-Werten zu selektieren. Verschiedene Methoden zur MOE-Messung werden untersucht: konventionelle statische Biegetests, axiale Kompression von Stäben, vorhandene (Ultra)-Schallmethoden, sowie ein spezielles Gerät zum Messen der Resonanz von kurzen Stäben. Holzeigenschaften und Fibrillenwinkel wurden an Scheiben gemessen, die von jedem Baum entnommen wurden. Die Ergebnisse zeigen eine gute Korrelation zwischen akustischen und statischen Messungen des MOE. Die sieben ausgewählten Klone unterschieden sich in ihrer Steifigkeit um den Faktor 2, wobei ein Großteil dieser Variationen mit Unterschieden im Mikrofibrillenwinkel zusammenhängt. Die Ergebnisse bestätigen die Vermutung, daß ein Potential zum Verbessern der Holzfestigkeit durch genetische Methoden bei Pinus radiata vorhanden ist. Diese Arbeit bietet keine definitiven Lösungen. Sie untersucht eine Anzahl von Ansätzen zur Selektion bei der Züchtung im Hinblick auf bessere Schnittholzprodukte. Die entwicklung von akustischen Methoden erwies sich als hilfreich beim notwendigen Massen-Screening der Festigkeitseigenschaften der Klone.
Abstract. Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land–atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The “sapfluxnetr” R package – designed to access, visualize, and process SAPFLUXNET data – is available from CRAN.
SUMMARYTracheid length, microfibril angle, spiral grain, wood density, MOE, MOR, compressive strength, modulus of rigidity and their inter-relationships were investigated for 50 Siberian larch trees (Larix sibirica) collected from five natural stands. No inter-stand variation in tracheid length, microfibril angle and spiral grain was observed. No effect of tracheid length and microfibril angle on the mechanical properties was observed. Inter-stand variation in wood density was significant especially within the latewood. Minimum density within a ring seemed to be the major source of variation for average density within the heartwood, whereas the effect of maximum density on average density was greater within the sapwood. Wood density, which was much higher for a given ring width than in plantation-grown Japanese larch (Larix kaempferi), had a major effect on the mechanical properties.
Bordered pit membranes of Cryptomeria japonica were examined successively from the outermost sapwood to the heartwood by scanning electron microscopy and by ultraviolet microspectrophotometry in an attempt to evaluate the time course of the secondary deposition of incrusting materials and to gain clues to their chemical composition. Scanning electron microscopy revealed that the bordered pit membranes were covered by incrusting materials from the middle layer of the sapwood to the heartwood. Both the amount and the appearance of the deposited incrusting materials differed among four regions of the wood, namely, the middle to inner layer of the sapwood, the innermost layer of the sapwood, the intermediate wood and the heartwood. From our results it appears that, in C. japonica, incrusting materials are deposited on bordered pit membranes by stages over several years. Apparent absorption of ultraviolet light by the bordered pit membranes was detected in the analysis of the innermost layer of the sapwood, the intermediate wood and the heartwood. The incrusting materials deposited in these zones were probably phenolic compounds. However, differences in the manner and extent of the absorption of ultraviolet light were found between these three regions of the wood. The results of microspectrophotometric analysis also suggested the phased deposition of incrusting materials at the bordered pit membranes of C. japonica.
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