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Despite growing interest in predicting plant phenological shifts, advanced spring phenology by global climate change remains debated. Evidence documenting either small or large advancement of spring phenology to rising temperature over the spatio-temporal scales implies a potential existence of a thermal threshold in the responses of forests to global warming. We collected a unique data set of xylem cell-wall-thickening onset dates in 20 coniferous species covering a broad mean annual temperature (MAT) gradient (−3.05 to 22.9°C) across the Northern Hemisphere (latitudes 23°–66° N). Along the MAT gradient, we identified a threshold temperature (using segmented regression) of 4.9 ± 1.1°C, above which the response of xylem phenology to rising temperatures significantly decline. This threshold separates the Northern Hemisphere conifers into cold and warm thermal niches, with MAT and spring forcing being the primary drivers for the onset dates (estimated by linear and Bayesian mixed-effect models), respectively. The identified thermal threshold should be integrated into the Earth-System-Models for a better understanding of spring phenology in response to global warming and an improved prediction of global climate-carbon feedbacks.

This study aimed to determine the influence of the stand age and selected weather conditions on the cambial activity, xylem and phloem formation and their development. For the analysis, microcores were taken weekly from two corresponding stands of Norway spruce (Picea abies (L.) Karst.) with various ages (35- and 106-years-old) during the growing season 2012 in the Czech Republic. Young specimens were characterised by higher cambium activity; however, more considerable variation and imbalance were found there. In old trees, delayed processes during the development of the xylem and phloem at the cell level were proved. The cambium activity started in March till mid-April, and it lasted for 22 weeks in both cases. The commencement of xylogenesis was established in the first half of May. In both investigated stands, the fully lignified ring was observed at the end of October. For the creation of most xylem cells, it was required 124 and 121 days in the young and old stands, respectively. Daily increment of 0.57 (young) and 0.49 (old) cells on average was observed during the active xylem growth. The relationship between air temperature and wood cell formation for both age groups was recorded. The precipitation influenced wood development just in the case of the young trees. Phloem formation was resistant to external influence according to the Pearson correlation coefficient. info:eu-repo/semantics/openAccess

We monitored six healthy dominant trees and six girdled Scots pine trees for two successive growing seasons (2014 and 2015) to investigate the seasonal dynamics, cambial activity, and morphology of the new xylem and phloem cells formed under environmental stress when girdling was applied during the dormant period (15 January 2014). Microcore (1.8 mm) samples were collected weekly using a Trephor tool above and below the girdling area, and weather data were measured on site. Drought stress in combination with girdling reduced the total number of differentiation days cell formation. In 2014, no significant differences in tracheid dimensions were observed between the girdled area and the control trees, while in 2015, the control trees showed significantly smaller cell wall thickness and radial dimensions of the latewood tracheids (LW) compared to 2014 and girdled trees had no occurrence of LW. Under stressful heat waves and prolonged periods of no precipitation, the trees tended to reduce the number of tracheids that were formed and exhibited smaller radial dimensions (narrower tree rings) to increase their hydraulic efficiency. Trees responded to limited water availability by forming intra-annual density fluctuations (IADFs L) in the zone of the LW to overcome stressful conditions. Although xylem cell differentiation was affected by stressful conditions, no significant variability in phloem cell dimensions was observed. Thus, the phloem tissue was less sensitive to exogenous factors.

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.

Important physical and mechanical properties were evaluated for Douglas-fir wood produced in a non-native environment. The specimens were obtained from 15 healthy co-dominant trees growing in three different sites located in the Czech Republic; they were studied for density, shrinkage, compression, and bending strength. The average density of the wood was 562.74 ± 62.47 kg·m-3 at 12% MC. The total volumetric shrinkage was in line with the respective literature, whereas the compression strength and modulus of rupture were found to be higher than the native Douglas-fir wood as well as several European softwoods. The properties of the wood produced in the Czech forests indicate the possibility of producing Douglas-fir timber of high quality.

Significance Forest trees can live for hundreds to thousands of years, and they play a critical role in mitigating global warming by fixing approximately 15% of anthropogenic CO2 emissions annually by wood formation. However, the environmental factors triggering wood formation onset in springtime and the cellular mechanisms underlying this onset remain poorly understood, since wood forms beneath the bark and is difficult to monitor. We report that the onset of wood formation in Northern Hemisphere conifers is driven primarily by photoperiod and mean annual temperature. Understanding the unique relationships between exogenous factors and wood formation could aid in predicting how forest ecosystems respond and adapt to climate warming, while improving the assessment of long-term and high-resolution observations of global biogeochemical cycles., Wood formation consumes around 15% of the anthropogenic CO2 emissions per year and plays a critical role in long-term sequestration of carbon on Earth. However, the exogenous factors driving wood formation onset and the underlying cellular mechanisms are still poorly understood and quantified, and this hampers an effective assessment of terrestrial forest productivity and carbon budget under global warming. Here, we used an extensive collection of unique datasets of weekly xylem tissue formation (wood formation) from 21 coniferous species across the Northern Hemisphere (latitudes 23 to 67°N) to present a quantitative demonstration that the onset of wood formation in Northern Hemisphere conifers is primarily driven by photoperiod and mean annual temperature (MAT), and only secondarily by spring forcing, winter chilling, and moisture availability. Photoperiod interacts with MAT and plays the dominant role in regulating the onset of secondary meristem growth, contrary to its as-yet-unquantified role in affecting the springtime phenology of primary meristems. The unique relationships between exogenous factors and wood formation could help to predict how forest ecosystems respond and adapt to climate warming and could provide a better understanding of the feedback occurring between vegetation and climate that is mediated by phenology. Our study quantifies the role of major environmental drivers for incorporation into state-of-the-art Earth system models (ESMs), thereby providing an improved assessment of long-term and high-resolution observations of biogeochemical cycles across terrestrial biomes.

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.

We analyzed the relationship between weather conditions and year-to-year (1981-1989) variation in the seasonal dynamics of cambial cell production (CCP) in Norway spruce in a monoculture forest area in the Czech Republic. We found that the timing of CCP greatly varied among the studied years. The onset of CCP occurred at the beginning of May and was strongly correlated with the April mean temperature. CCP ceased by the end of August. The timing of the cessation of CCP was more variable among trees and among years than its onset. The amount of precipitation positively influenced the duration of CCP and the average rate of cell production positively correlated to the minimum temperature in January-April, as well as the maximum temperature during the growing period. Our results show that the timing and the rate of CCP of xylem cells are influenced by temperature and precipitation. However, weather-xylem growth relations of spruce from temperate forests under climatic conditions are complex, since trees are known to respond less strongly to climatic average variation than influences of extreme conditions.

Given recent climatic trends, it is crucial to understand the plasticity and adaptiveness of forest trees in order to evaluate their current and future responses to changing climatic conditions. We investigated inter- and intra-annual xylem growth and its relation to weather factors in European beech ( Fagus sylvatica ) and a co-occurring conifer, either Norway spruce ( Picea abies ) or Scots pine ( Pinus sylvestris ), at five sites with different elevations and climatic conditions, in Spain, Slovenia and the Czech Republic. The selected sites were located in central and marginal parts across the distribution range of the investigated species. The results showed that climate-growth relationships vary between different species at the same site and within the same species at different sites, indicating diverse survival strategies among the observed species but also high plastic capacity within the same species. Moreover, xylogenesis analysis revealed the capacity of trees to adapt the beginning and cessation of wood formation depending on conditions. In case of beech, shortening growth duration in dryer and warmer environments and the opposite in the case of conifers, with which the growing period was extended in such conditions. Consequently, the plasticity capacity of beech was limited due to short growth duration, while conifers (especially pine) proved to be able to compensate climatic constrictions by growing over a longer period and becoming more adapted to survival in drought-prone environments.

The metabolic activity of phytohormones and the accumulation of carbohydrates affect the reactivation of the cambial zone and the radial increment of woody plants. We aimed to monitor the dynamics of indole-3-acetic acid (IAA) concentration and amounts of soluble carbohydrates during xylem and phloem formation of one growing season (2015). Six sample trees of Scots pine (Pinus sylvestris L.), aged 80 years on average, growing in the Sobešice research site (404 m a.s.l.) in the Czech Republic were selected. We obtained microcore samples at weekly intervals by the Trephor tool method for cell formation analysis and spectrophotometric determination of IAA and soluble carbohydrate contents. We found that time of the highest concentration of IAA (last week of April) coincided with time of the maximum number of cells in the cambial zone and highest expansion of the cell enlargement stage. When the IAA concentration was too low to be measured, latewood tracheids started to form, and late phloem sieve cell formation ceased. The highest concentration of soluble carbohydrates was 200.40 +- 21.6 µg GLU per sample (May 14). This coincided with the fastest weekly xylem cell increment. This research shows that IAA and soluble carbohydrate dynamics directly affects xylem and phloem formation. info:eu-repo/semantics/openAccess

Over the course of a year, tree physiological processes are not only directly affected by environmental conditions, but also by the tree’s own phenological stages. At the same time, phenological stages should, to a certain degree, reflect tree physiology. However, we have rather poor knowledge of the details of the interplay between phenology and ecophysiology. The objective of this study was to develop a better understanding of the links between phenology and ecophysiology. We investigated the degree to which various physiological processes are synchronized both with each other and with phenology and what information related to phenology can be obtained from instrumental ecophysiological measurements. Phenological observations, along with measurements of transmittance of photosynthetically active radiation (PAR), stem volume changes, sap flow and xylogenesis were conducted in a 45-year old European beech (Fagus sylvatica) stand in the Czech Republic. Results indicated that ecophysiology was tightly related with the phenological stage of the tree. Early spring phenological stages were closely linked with the beginning of cambial activity and the onset of sap flow, i.e., the first leaves were produced simultaneously with the beginning of stem radial growth. The highest xylem growth rates occurred in June, simultaneously with the highest sap flow rates. Cambial activity ceased with the onset of summer leaf coloring at the end of July, at the same time as the permanent decrease in sap flow rate. The end of cell wall maturation was linked to the onset of autumn leaf coloring. We conclude that instrumental measurements of tree and stand ecophysiology provided additional information better specifying the onset of particular phenostages. In our case, twelve permanently located sensors used to measure PAR transmittance captured leaf area development with acceptable accuracy, thus limiting the need for frequent visits to the forest site in the spring and autumn. Moreover, data from dendrometers showed linkages to bud break and the onset of leaf coloring. Therefore, ecophysiological measurements increased the effectiveness and accuracy of phenological observations and provided additional information about tree development in particular external conditions.

VAVRCIK, H., GRYC, V.: The methodology of making microscopical preparations of wood. Acta univ. agric. et silvic. Mendel. Brun., 2004, LII, No. 4, pp. 169-176 In this paper, there are discussed methods of making woody tissues microscopical preparations and making its microslides. There are described common methods of preparation of wood blocks, sectioning of woody tissues, staining and mounting. The differences of making wood sections and non-lignified plant sections are highlighted. The authors recommendate the fast methodology of making quality microslides of wood sections based on their own experiences. wood, microslides, microscopical preparations, methods

In the present study, anatomical features were used to identify tree species chosen to craft farming tools from the 19th and first half of the 20th century preserved in specimen inventories of the open-air museum in Stražnice, south-eastern Moravia (Czech Republic). In total, 701 samples from 337 historical farming tools were obtained from museum specimens. The samples were identified at micro- or macroscopic levels, or both. Results indicated local people used floodplain forest wood to construct farming tools in the study region. Nineteen wood species were identified; from this total, those with higher densities and better mechanical properties were used to manufacture tools, and included predominantly beech, oak, and ash. Softwood species, with lower densities were mainly used for chiseled out implements. We hypothesized regional forest species composition played an essential role in woody species choice, however the species also possessed appropriate properties. Cultivated tree species, such as fruit trees, were employed to create common objects; however, currently, these species are typically applied for special purposes. We concluded an increased number of species were employed in the past for utilitarian purposes, including tree species grown outside local forest boundaries, including cultivated fruit tree species; and species were utilized with good, although perhaps tacit, knowledge of their properties.

Oven-dry wood density variations are reported for European ash (Fraxinus excelsior L.) and English oak (Quercus robur L.) trees growing in floodplain mixed forests in South Moravia, Czech Republic. Two sites with different water regime conditions were selected along the Dyje (site A) and the Morava (site B) Rivers. In total, 20 dominant, healthy trees were chosen to determine the tree-ring structure and the oven-dry wood density (ρ0) along the radius of the stem cross section. The tree-ring width followed the common trend of a general decline as the trees aged. After removing the age influence, significant differences were observed in the tree-ring structure, recorded several years after water regime treatments. The European ash and the English oak ρ0 were found to be 677.3 kg∙m-3 and 618.2 kg∙m-3, respectively, significantly differing between the sites, for both species. High variability of ρ0 was also noticed along the stem radius in both species and sites.

Scots pine ( L.) is a resilient, wide spread species. This paper reports on the xylem and phloem cell formation process, before and after, the species was put under artificial stress by stem girdling. Microcore method was applied to a healthy control group and a standing group of girdled trees within an 80-year-old pine forest for two consecutive growing seasons (2013 and 2014). The stem girdling was applied in the middle of the first growing season (July 2013). Cambial activity timings (onset and cessation of cell division), cell formation intensity, cell differentiation, and the dynamics of the annual radial increment in the stem were analyzed. Cambial activity was inhibited and eventually ceased below the stem girdling immediately after the removal of the strip. Therefore, no latewood tracheids were formed. However, above the stem girdling and in the control trees, cell formation and tissue differentiation continued until the end of the growing season, with the girdled trees moving at a less intensive pace but for a longer period of time. During the following growing season (2014), the cambial zone was reactivated only above the stem girdling, not below, and eventually the girdled trees died. In 2014, the onset of the cambial activity was delayed and the division rate of the cells was slower in the girdled trees. Furthermore, the girdled trees formed less phloem cells than the control trees.Pinus sylvestris

GRYC, V., VAVRCIK, H., GOMOLA, S.: The variability of selected properties of beech (Fagus sylvatica L.). Acta univ. agric. et silvic. Mendel. Brun., 2007, LV, No. 4, pp. 29–36 Variability of ring width, wood density and swelling in beech from two different areas was analysed. The variability of each property was described along the stem radius. The analysis proved that the ring width decreased in direction from the pith to the outer part of the stem (cambium). Statistically signifi cant difference of mean ring width between locality 1 and 2 was not found. Density and volumetric swelling of wood were statistically signifi cantly different between localities. Results showed that the density and volumetric swelling decreased from pith to cambium. Statistically signifi cant dependency between density and volumetric swelling of wood was proved. The average wood density of beech was 752 kg·m –3 at 12% moisture content. beech wood, tree ring, density, structure of wood Dřevo je významnou obnovitelnou surovinou, na niž je vedle lesnictvi a dřevařstvi zavisla řada dalsich průmyslových odvětvi. Na rozdil od ostatnich průmyslových materialů ma tu výhodu, že je surovinou obnovitelnou. Je nutne mit na paměti, že dřevo je přirodnim materialem, který ma na rozdil od větsiny ostatnich materialů velmi variabilni strukturu a vlastnosti. Struktura dřeva a nasledne vlastnosti jsou urcovany v průběhu růstu stromu (Gryc a Horacek, 2004). Buk lesni (Fagus sylvatica L.) patři k nejvýznamnějsi listnate hospodařske dřevině nejen v Ceske republice, ale i v ostatnich statech středni Evropy. Plosne zastoupeni v roce 2005 bylo 6,6 % z celkove plochy ceských a moravských lesů (Zprava o stavu lesa a lesniho hospodařstvi Ceske republiky, 2005). Za zakladni ukazatel kvality dřeva lze považovat hustotu dřeva, ktera významným způsobem ovlivňuje větsinu jeho fyzikalnich a mechanických vlastnosti. Průměrna hustota dřeva se v připadě buku pohybuje kolem 720 kg·m –3 při vlhkosti 12 % (Trendelenburg

The aim of this work was to carry out a tree-ring analysis, to determine density, shrinkage and compressive strength parallel to the grain of Blue spruce (Picea pungens Engelm.) wood. Results of this work were specific due to the non-forest origin of the sample material that was from two solitaire trees. Tree ring analysis (determination of tree ring width and portion of latewood) was carried out on the transverse section of a stem that was taken at height of 0.3 m from the tree base. Wood properties were tested according to Czech technical standards.Trees showed wide tree rings (5.65 mm) with a small portion of latewood (12.55 %). Oven dry wood density was 371.66 kg . m−3, overall volumetric shrinkage was 9.12 % and compressive strength parallel to the grain was 42.10 MPa. Due to the low age of trees results are valid for juvenile wood.Wood properties were examined along the stem radius. Tree ring width was increasing to the age of 12th year subsequently it was constant. Tree ring width was constant along the entire stem radius. Wood density, overall volumetric shrinkage and compressive strength parallel to the grain were increasing in the direction from pith to bark.

The paper is aimed at the field of the microscopic structure of wood dealing with the description of the most important anatomic element in softwood – tracheids in a stem with the occurrence of reaction wood. Significant changes of tracheids were found along the height and radius of a stem. There were statistically significant differences between particular annual rings (variability along the stem radius). The height of a stem was also statistically significant. On the basis of the results obtained 3D models were created (for zones compression wood, opposite wood and site wood; models for radial dimension an early-wood tracheid and late-wood tracheid) depicting changes in transverse dimensions of the spruce tracheid in relation to its position in a stem. Structure of ring with compression wood was studied too. It was observed that the ring with occurrence of compression wood has a following structure: early wood tracheids at the beginning of the growing season, transitional tracheids, compression tracheids and at the end of an annual ring typical late wood tracheids. The rings with compression wood show more tracheids as compared with annual rings from the opposite side.

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.

The differences in the microscopic structure of wood based on the variables of earlywood vessel area and tree ring width were analysed in 6 trees of Pedunculate oak (Quercus robur L.) and 6 trees of Sessile oak (Quercus petraea (Mattuschka) Liebl.) in the same forest stand at a site in the Vizovice Highland (Czech Republic). The aim of this paper was to assess any differences between the two oak species when grown in the same location. Also the effect of tree-ring width and the effect of age on earlywood vessel variables were analysed. Mean values of tree-ring widths were not different between species. Earlywood vessel area chronologies were synchronized well between species. The mean values of earlywood vessel area (average vessel area, average vessel area of the first row of vessels, area of the largest vessel) showed a significant difference. Finally, we can conclude that there were differences in vessel features between these oak species.

Temperature, water availability and photoperiod are the primary drivers of tree phenological processes. However, there is lack of information how the spring temperature and summer drought affect phenology of both cambium and needles. We evaluated the interplay between xylem and needle development of mature Scots pine trees in three consecutive years differing in the spring temperatures and onset and duration of summer drought. Cambial activity began on the day of a year (DOY) 83–87, while the bud break occurred on DOY 113–119, when also the secondary cell wall of tracheids started its formation. While the timing of bud break correlated with the sum of effective temperatures, the beginning of cambial zone activity did not. The needles were fully unfolded around DOY 170, which corresponded to the transition between earlywood and latewood tracheids. Summer drought did not affect needle development, but it changed the rate of production and morphology of latewood tracheids. Latewood tracheids from the year 2015 when the drought was longest (i.e. until the second half of August in 2015 compared to the duration from June until the middle of July in the two other years) were 32% narrower and they had 34% thinner cell walls than in 2014 and 2016. The improvement of tree water status in July resulted in the formation of intra-annual density fluctuations (IADF). The interplay between needle and cambium phenology provided an insight into how the tree allocates the resources with varying temperature and soil water availability.

The dynamics of xylem formation in young Norway spruce (Picea abies (L.) Karst.) trees was analysed during one growing season in Rajec-Němčice in the Czech Republic. Microcores were taken from six 34-year-old trees in April to October 2009 at weekly intervals by means of a Trephor tool in a second generation spruce monoculture stand. The cambium activity started between 16–30 April and the last cells divided between 27 August and 17 September. The average length of cambium activity was 5.2 months. The cambium achieved its maximum width (12.3 cell layers) in June, whereas the dormant cambium contained 5.3 cell layers on average. Fitting the xylem increments to the Gompertz function showed that the period of most intensive cell formation was at the beginning of July. The total time necessary for the development of most cells was 156 days when modelled with WCDcalc script and 117 days when modelled with the Gompertz function.

Various environmental conditions (heat waves and drought events) strongly affect leaf and xylem phenology. Disentangling the influence of temperature, precipitation and soil moisture content (AWR) on the forest productivity remains an important research area. We analyzed the impact of climate variability on the leaf phenology (10 sample trees) and radial growth (17 sample trees) of European beech ( L.). The study was conducted on 130-year-old European beech trees growing in a temperate forest stand in the Czech Republic. Detailed 20-year phenological monitoring was performed at the study site (1992–2011). As expected, leaf phenological events were mainly driven by the growing season temperatures. Leaf unfolding was highly affected positively by spring temperatures and the top-layer (to 40 cm) AWR in March. The correlation of tree-ring width with the interpolated climate data was positive significant for the growing season AWR and precipitation signal. Furthermore, the water availability in the top soil layer was found to be an important predictor of tree growth and extremely low growth occurrence. The extended phenological growing season, which was caused by a temperature increase, was not followed by an increased tree-ring width. The examined relationships point out the significance of the water availability in the top soil layer in European beech stands.Fagus sylvatica

The processes of xylogenesis are very often studied with use of repeated micro-sampling method. Microcores are taken throughout the growing season. After paraffin embedding and cutting on a rotary microtome permanent microslides are prepared. The numbers of cells (tracheids) are counted for each of the three zones – radially enlarging (G), maturing (D) and matured (T) zone of the developing growth ring. These numbers of cells are an input for the R script named WCDcalc that was developed for the calculation of durations and timing of cell differentiation in developing growth rings of softwoods. WCDcalc produces a plain text file as an output and a bar plot. For each cell there is a date in day of year format (DOY) that represents the day when the cell entered the particular zone, and the duration for which the particular cell was in the zone of the developing growth ring. The bar plot interprets results graphically in two forms. First, it is shown on the display, second, it is saved as an EPS file.WCDcalc is an R script written in R language. It can be run only in R environment. WCDcalc ( http://xylogenesis.wz.cz ) was released under GNU General Public License.

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.

Nowadays many scientific 3D models of wood are available. These models are suitable only for simulation of physical fields movements in wood but not for educational purposes especially demonstration of microscopic structure of wood.3D structure of ring-porous hardwood species was created. European ash (Faraxinus excelsior L.) was selected due to its relatively simple wood structure than other wood species within ring-porous group. The model was created by manual modelling process in Rhinoceros 4.0 that is a software for visualization and modelling. Microslides were prepared from sample of ash to take micro photos that were used as a visual source for modelling. Beside these pictures made by authors of this paper other microphotos from wood anatomy publications were used. Created 3D model of ash is a VRML object (Virtual Reality Modelling Language). This format is available to viewing and presentation with severe freeware VRML browsers. These VRML browsers are available as a plug-in for standard internet browsers or as standalone VRML browsers. The model is useful for studying and teaching microscopic structure of ring‑porous hardwood species. It was created such a way to be as exact copy of original anatomical structure of ash wood as possible. The paper may be used as a cue for other authors to create their own 3D models of different wood kinds.

The aim of this study was to compare the structure of beech juvenile and mature wood in relation to wood density. The comparative analysis between juvenile and mature wood examined the diameter of vessels, the width and height of pith rays, and the number of vessels and pith rays per 1 mm 2 . The results show that the average vessel diameter as well as the width and height of pith rays reach statistically lower values in juvenile wood than in mature wood. On the other hand, no significant difference between the two types of wood has been found in terms of the frequency of vessels per 1 mm 2 . Having said that, the difference in the frequency of rays per 1 mm 2 between juvenile and mature wood is far from being negligible; juvenile wood has three times as many pith rays as mature wood. The density of juvenile wood is higher (ρ 12 = 726.07 kg/m 3 ) than the density of mature wood (ρ 12 = 701.50 kg/m 3 ).

Wood is a hygroscopic material that is affected by shape changes. The aim of this study was to analyse the variability of wood swelling in the individual anatomic directions. Wood swelling was examined on a sample tree containing compression wood. With regard to the presence of compression wood, the sample tree was divided into the following three zones: the compression wood zone (CW), the opposite wood zone (OW), and two side wood zones (SWL and SWR). The results show that the wood containing compression wood swells less at the transverse plane (in the radial and tangential direction). Conversely, the swelling of compression wood in the longitudinal direction is higher. The same proportion was established in the swelling coefficient that grew proportionally to the increasing wood density in all anatomic directions. The proportion of compression wood manifested its effects in different ways. Transversely (in the radial and tangential direction) the swelling coefficient decreased proportionally to the increasing percentage of compression wood, longitudinally, however, the opposite was the case.

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.

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.

A multi proxy approach was applied in the reconstruction of the architecture of Medieval horse stable architecture, the maintenance practices associated with that structure as well as horse alimentation at the beginning of 13th century in Central Europe. Finally, an interpretation of the local vegetation structure along Morava River, Czech Republic is presented. The investigated stable experienced two construction phases. The infill was well preserved and its composition reflects maintenance practices. The uppermost part of the infill was composed of fresh stabling, which accumulated within a few months at the end of summer. Horses from different backgrounds were kept in the stable and this is reflected in the results of isotope analyses. Horses were fed meadow grasses as well as woody vegetation, millet, oat, and less commonly hemp, wheat and rye. Three possible explanations of stable usage are suggested. The stable was probably used on a temporary basis for horses of workers employed at the castle, courier horses and horses used in battle.

Istraživanja su provedena u 95-godišnjoj visokoproduktivnoj sastojini crne johe (Alnus glutinosa Gaertn.) u Podravini. Cilj ovoga rada je istražiti glavna obilježja akumulacije i dinamike ugljika i dušika u sastojini crne johe, kao indikatora stabilnosti ekosustava i održivosti gospodarenja ovom sastojinom. Analiza dinamike i akumulacije ugljika i dušika tijekom godine obuhvatila je istraživanje tla, posebice šumske prostirke i A- horizonta, drva i kore crne johe te lista neposredno nakon odbacivanja. Masa šumske prostirke kreće se od 4,71 Mg ha–1 nakon odbacivanja lista, preko 3,36 Mg ha–1 u proljeće, do 0,51 Mg ha–1 u jesen prije ponovnog odbacivanja lista. Od jeseni do proljeća raste sadržaj ugljika i dušika u A- horizontu, a zatim ponovno opada. Akumulacija ugljika u nadzemnoj biomasi sastojine sredinom ljeta je 214,6 Mg ha–1, a u tlu je prosječno 143,5 Mg ha–1. S druge strane akumulacija dušika veća je u tlu – u nadzemnoj biomasi je 2 Mg ha–1, a u tlu dosiže čak i preko 14 Mg ha–1 (prosječno 13,8). Sveukupna akumulacija organskog ugljika u ekosustavu je 359,5 Mg ha–1, a dušika 15,8 Mg ha–1. Istraživanje je pokazalo da se radi o izuzetno vitalnoj sastojini, očito s izuzetno dobrim ekološkim uvjetima za rast crne johe. Njena se vitalnost i dugoročna stabilnost najbolje odražavaju u postojanom indeksu širine godova u posljednjih 80 godina, što potvrđuje i vrlo velika drvna zaliha, koja za sastojinu starosti 93–98 god. iznosi 751 m3 ha–1 (iznad taksacijske granice od 7 cm)., This research was conducted in a 95-year-old, highly productive stand of black alder growing in the Drava plain in Croatia. The goal was to investigate the main features of carbon-nitrogen accumulation and dynamics in the stand of black alder (Alnus glutinosa (L.) Gaertn.), as an indicator of ecosystem stability and sustainability of managing such stands. Soil physiography was investigated in a permanent sample plot sized 1 ha with growing stock of 751 m3 ha–1. In the course of one season of leaf litter decomposition, the forest floor and soil from the A horizon were sampled on three occasions; the first sampling took place after leaf drop in 2009, the second at the beginning of vegetation (April 2010), and the third before leaf drop (beginning of November 2010). The forest floor mass was determined and so was the carbon and nitrogen content in the forest floor, in the bark, in the physiologically mature leaf and in the soil, as well as the soil pH value. Dendrochronological analysis was performed on black alder wood specimens to determine wood density and carbon and nitrogen content. Data from piezometers set up within the plot for the period 1997–2000 were used to interpret the water regime. According to the research, the soil is Haplic Gleysol (Endoarenic), with a relatively shallow A horizon, of sandy-clayey to loamy-sandy texture, of weakly acidic and in the deeper part weakly alkaline reaction. The water regime is characterized by a shallow and stable groundwater level which occasionally causes shallow (up to 20–30 cm) flooding in the out-of-vegetation period, and does not drop below 130 cm in the vegetation period. The forest floor mass ranges from 4.71 Mg ha–1 after leaf drop, over 3.36 Mg ha–1 in the spring, to 0.51 Mg ha–1 in the autumn before renewed leaf drop, which indicates complete decomposition of black alder leaf litter in a yearly cycle. During this period the C:N ratio decreases from 19 to 14.8. Carbon and nitrogen content in the A horizon increases from autumn to spring, but drops again afterwards. Simultaneously, the pH value significantly drops from autumn to spring, but rises again by autumn. In mid-summer, carbon accumulation in the above-ground biomass of the stand is 214.6 Mg ha–1, while in the soil it is 143.5 Mg ha–1 on average. On the other hand, nitrogen accumulation is higher in the soil: while it is 2 Mg ha–1 in the above-ground biomass, it reaches over 14 Mg ha–1 (13.8 on average) in the soil. Overall accumulation of organic carbon in the ecosystem is 359.5 Mg ha–1, and of nitrogen it is 15.8 Mg ha–1. The research has confirmed that this is an exceptionally vital stand, evidently with excellent ecological conditions for the growth of black alder. The vitality and long-term stability of this stand is best reflected in the stable ring width index in the past 80 years, as confirmed by the very large growing stock amounting to 751 m3 ha–1 for a stand aged 93–98 (above the taxation limit of 7 cm).

The aim of research was to find out the variability of spruce ( Picea abies (L.)) Karst.) wood compression strength limits in the direction parallel to grain. The wood strength was examined using samples from a tree with present reaction (compression) wood. The strength was found out for individual stem zones (CW, OW, SWL and SWR). The zone with present compression wood (CW) demonstrated slightly higher values of wood strength limits. The differ - ences in the limits of compression strength parallel to grain in individual zones were not statistically significant. All the data acquired by measuring were used to create 3D models for each zone. The models describe the strength along the radius and along the stem height. The change of strength along the stem radius was statistically highly significant. There was an obvious tendency towards an increase in the strength limit in the first 40 years. With the increased stem height, there is a slight decrease in wood strength.

The objective of this study was to investigate the basic wood density (rho(k) ) of the silver birch (Betula pendula Roth.) trees in relation to the stand structure. This research was conducted in three stands of different structure and ages, located in the region of the lower part of the Jesenilcy Mountains in the Czech Republic. In total, 71 healthy dominant silver birch trees were randomly selected. Two samples (cores) were taken per tree for performing the tree-ring width analysis and rho(k) determination. We found that the average rho(k) of the three examined stands ranged from 471.8 to 494.6 kgm (-3) . The older trees showed a high variation of the rho(k). The age of the tree and stem diameter positively influenced the rho(k). Nevertheless, it was noted that the slenderness ratio had a negative influence on the rho(k). Overall, the prediction of wood density using stand and tree characteristics, even when the management history records are available, remains a complex hypothesis. info:eu-repo/semantics/openAccess