Vladimír Gryc

Woody biomass production lags stem-girth increase by over one month in coniferous forests

Wood is the main terrestrial biotic reservoir for long-term carbon sequestration(1), and its formation in trees consumes around 15% of anthropogenic carbon dioxide emissions each year(2). However, the seasonal dynamics of woody biomass production cannot be quantified from eddy covariance or satellite observations. As such, our understanding of this key carbon cycle component, and its sensitivity to climate, remains limited. Here, we present high-resolution cellular based measurements of wood formation dynamics in three coniferous forest sites in northeastern France, performed over a period of 3 years. We show that stem woody biomass production lags behind stem-girth increase by over 1 month. We also analyse more general phenological observations of xylem tissue formation in Northern Hemisphere forests and find similar time lags in boreal, temperate, subalpine and Mediterranean forests. These time lags question the extension of the equivalence between stem size increase and woody biomass production to intra-annual time scales(3, 4, 5, 6). They also suggest that these two growth processes exhibit differential sensitivities to local environmental conditions. Indeed, in the well-watered French sites the seasonal dynamics of stem-girth increase matched the photoperiod cycle, whereas those of woody biomass production closely followed the seasonal course of temperature. We suggest that forecasted changes in the annual cycle of climatic factors(7) may shift the phase timing of stem size increase and woody biomass production in the future.

Plastic and locally adapted phenology in cambial seasonality and production of xylem and phloem cells in Picea abies from temperate environments

Despite its major economic importance and the vulnerability of Picea abies (L.) H. Karst. to climate change, how its radial growth at intra-annual resolution is influenced by weather conditions in forest stands with a high production capacity has scarcely been explored. Between 2009 and 2011, phenological variation in seasonal cambial cell production (CP) was analysed in adult P. abies trees from three contrasting sites, differing in altitude and latitude. The results indicate that the timing of cambial CP is a highly synchronic process within populations since in all cases the cambium simultaneously started and stopped producing xylem and phloem cells. Our results also demonstrate that the phenology of cambial CP is highly variable and plastic between years, depending on seasonal temperature and precipitation variation. Differences among sites, however, are only partially explained by different environmental (elevation and altitude) and climatic conditions, suggesting that local adaptation may also play a decisive role in the strategy of P. abies for adapting wood and phloem increments to function optimally under local conditions.

Plasticity in variation of xylem and phloem cell characteristics of Norway spruce under different local conditions

There is limited information on intra-annual plasticity of secondary tissues of tree species growing under different environmental conditions. To increase the knowledge about the plasticity of secondary growth, which allows trees to adapt to specific local climatic regimes, we examined climate–radial growth relationships of Norway spruce [Picea abies (L.) H. Karst.] from three contrasting locations in the temperate climatic zone by analyzing tree-ring widths for the period 1932–2010, and cell characteristics in xylem and phloem increments formed in the years 2009–2011. Variation in the structure of xylem and phloem increments clearly shows that plasticity in seasonal dynamics of cambial cell production and cell differentiation exists on xylem and phloem sides. Anatomical characteristics of xylem and phloem cells are predominantly site-specific characteristics, because they varied among sites but were fairly uniform among years in trees from the same site. Xylem and phloem tissues formed in the first part of the growing season seemed to be more stable in structure, indicating their priority over latewood and late phloem for tree performance. Long-term climate and radial growth analyses revealed that growth was in general less dependent on precipitation than on temperature; however, growth sensitivity to local conditions differed among the sites. Only partial dependence of radial growth of spruce on climatic factors on the selected sites confirms its strategy to adapt the structure of wood and phloem increments to function optimally in local conditions.

The analysis of tropical wood discoloration caused by simulated sunlight

This study investigated the wood surface discoloration due to simulated sunlight of tropical woods native to South America. Wood of jatoba (Hymenaea courbaril L.), massaranduba (Manilkara bidentata A. Chev.), tigerwood (Astronium graveolens Jacq.), angelim amargoso (Vatairea spp.), angelim pedra (Hymenolobium spp.) and angelim vermellho (Dinizia excelsa Ducke) was exposed to a treatment by xenon-arc lamp light simulating outdoor sunlight, for 144 hours. Colour measurement of exposed and non-exposed areas of samples was performed by means of a spectrophotometer measuring in CIEL∗a∗b∗ colour system. The resulting wood discoloration was evaluated according to the value of the overall colour change ΔE∗. Changes of particular parameters (L∗,a∗ and b∗) were also observed during exposure. The wood surface darkened rapidly during the first hours of exposure to simulated sunlight. Later, samples showed only a slight increase in lightness. Within one wood species the colour changes were more significant (higher ΔE∗) for lighter samples.ZusammenfassungIn dieser Studie wurde die Verfärbung von Holzoberflächen aufgrund von simulierter Sonneneinstrahlung an den in Südamerika beheimateten tropischen Holzarten Jatoba (Hymenaea courbaril L.), Massaranduba (Manilkara bidentata A. Chev.), Tigerwood (Astronium graveolens Jacq.), Angelim amargoso (Vatairea spp.), Angelim pedra (Hymenolobium spp.) und Angelim vermellho (Dinizia excelsa Ducke) untersucht. Dabei wurden diese über eine Dauer von 144 Stunden mit einer Xenonlampe bestrahlt. Mit einem Spektralphotometer wurden Farbmessungen an bestrahlten und nicht bestrahlten Probenflächen unter Verwendung des CIEL∗a∗b∗ Farbsystems durchgeführt. Die Gesamtverfärbung wurde entsprechend des Wertes ΔE∗ beurteilt. Bei der Bestrahlung wurde die Änderung der Parameter L∗,a∗ und b∗ ebenfalls bestimmt. In den ersten Stunden der Bestrahlung dunkelte die Holzoberfläche schnell, später nahm die Helligkeit leicht zu. Innerhalb einer Holzart waren die Farbveränderungen bei den helleren Proben stärker ausgeprägt (größeres ΔE∗).

THE EFFECTS OF DROUGHT ON WOOD FORMATION IN FAGUS SYLVATICA DURING TWO CONTRASTING YEARS

We studied the effect of local weather conditions on intra-annual wood formation dynamics and wood structure of European beech (Fagus sylvatica L.) from a temperate location in the Czech Republic in two consecutive years, 2010 and 2011, characterized by different amounts of precipitation. Microcores were taken at weekly intervals and transverse sections of cambial and xylem tissue were prepared for light microscopic observation. Air temperature and soil moisture content were measured daily at the research plot. Tree-ring formation patterns and vessel features showed different responses to climatic factors in the two years. In 2010, the onset of cambial cell production occurred almost 10 days later than in 2011, when a considerably reduced amount of rainfall was already observed in the winter and spring months, as shown in Standardized Precipitation Index (SPI) values. Lack of precipitation in 2011 caused premature cessation of cambial cell division and markedly narrower annual xylem increments. Vessel density and water conductive area were higher in 2011 than in 2010. Average vessel size in general did not change. In response to local weather conditions, beech controls its hydraulic conductivity mainly by changing the number of vessels and tree growth rate, followed by vessel size. The lower sensitivity of vessel diameter to hydrological alterations confirms previous studies by other authors.

The influence of wood density on longitudinal wave velocity determined by the ultrasound method in comparison to the resonance longitudinal method

The paper deals with the relationship between density and the velocity of sound wave propagation in wood. The wave velocity was measured using the heartwood of doussie (Afzelia bipindensis), merbau (Intsia bijuga), panga panga (Miletia stuhlmannii Taub.), tigerwood (Astronium graveolens Jacq.) and zebrano (Microberlinia brazzavillensis) by the two methods: ultrasound and resonance longitudinal. The velocity measured by the ultrasound method was always higher than the values gained by the resonance longitudinal method. However, there is a high correlation between the results of both methods. A change in sound wave velocity due to a change in density was not confirmed for any of the species. A similar conclusion was reached in the comparison among species.

Cenomanian angiosperm wood from the Bohemian Cretaceous Basin, Czech Republic.

The first permineralized angiosperm wood from the Cenomanian of the Bohemian Cretaceous Basin (Czech Republic) is described. The wood is diffuse porous, with vessels solitary and in radial multiples of 2–5, perforation plates are exclusively simple, and tyloses abundant. Rays are usually 4–7-seriate and heterocellular, narrower rays are rare. The fossil is designated as Paraphyllanthoxylon aff. utahense Thayn, Tidwell et Stokes. Other occurrences of Paraphyllanthoxylon are reviewed and the equivocal botanical affinity of the taxon is discussed.

The Relation of Fibre Length and Ray Dimensions to Sound Propagation velocity in wood of selected Tropical Hardwoods

This study investigates the relation of fibre length and ray dimensions to the sound propagation velocity in four commercial tropical hardwoods. The species used in the study were Doussie (Afzelia bipindensis Harms), Merbau (Intsia bijuga (Colebr.) Kuntze), Muiracatiara (Astronium graveolens Jacq.) and Wenge (Millettia laurentii De Wild.). The sound propagation velocity was established by the frequency-resonance method. A positive correlation was obtained between fibre length and sound velocity within species. The correlation was stronger in species with a higher proportion of libriform fibres. A trend analogous to fibre length within species was observed for ray ratio but, in contrast to fibre length, the correlation was strong also between species. The samples with higher and at the same time narrower rays (higher ray ratio) showed a higher velocity of sound propagation along the grain.

Changing Face of Wood Science in Modern Era: Contribution of Nanotechnology

BACKGROUND Wood science and nanomaterials science interact together in two different aspects; a) fabrication of lignocellulosic nanomaterials derived from wood and plant-based sources and b) surface or bulk wood modification by nanoparticles. In this review, we attempt to visualize the impact of nanoparticles on the wood coating and preservation treatments based on a thorough registration of the patent databases. METHOD The study was carried out as an overview of the scientifically most followed trends on nanoparticles utilization in wood science and wood protection depicted by recent universal filed patents. This review is exclusively targeted on the solid (timber) wood as a subject material. RESULTS Utilization of mainly metal nanoparticles as photoprotection, antibacterial, antifungal, antiabrasive and functional component on wood modification treatments was found to be widely patented. Additionally, an apparent minimization in the emission of volatile organic compounds (VOCs) has been succeeded. CONCLUSION Bulk wood preservation and more importantly, wood coating, splay the range of strengthening wood dimensional stability and biological degradation, against moisture absorption and fungi respectively. Nanoparticle materials have addressed various issues of wood science in a more efficient and environmental way than the traditional methods. Nevertheless, abundant tests and regulations are still needed before industrializing or recycling these products.

Wood anatomy and acoustic properties of selected tropical hardwoods

Selected anatomical features and ground tissue composition were studied in four tropical hardwoods (Afzelia sp. [Doussie], Intsia sp. [Merbau], Astronium sp. [Muiracatiara] and Millettia sp. [Wenge]). These woods can be applied in musical instrument production, especially for xylophone bars. The measured density, 1st bending natural frequency and the logarithmic decrement of damping were used to calculate other acoustic properties such as dynamic young modulus of elasticity (Erf ), specific modulus of elasticity (E´/ρ), internal friction (tan δ), and acoustic conversion efficiency (ACE).The correlations between anatomy and acoustic properties were determined. Despite difficulties in specifying general characteristics of hardwoods due to their complicated and variable structure, correlations valid between species were found for specific modulus of elasticity. Specific modulus of elasticity was negatively correlated with ray tissue volume and positively with ray height to width ratio and fiber length. The diversity in ground tissue composition was the main criterion for the species choice and probably should condition diverse correlations of anatomical features found for individual species. It seems that better acoustic properties (higher stiffness, ACE or specific modulus of elasticity) are performed by wood with longer fibers and slender rays, causing minimal deflection of adjoining fibers.