Description of Intra-Annual Changes in Cambial Activity and Differentiation of Secondary Conductive Tissues of Aesculus hippocastanum Trees Affected by the Leaf Miner Cameraria ohridella

Aesculus hippocastanum trees are commonly infested by the leaf miner Cameraria ohridella, whose larval activity causes the destruction of the leaf parenchyma and induces defoliation. Pest attacks result in, e.g., production of smaller fruits and tree re-flowering in autumn. Concerning pest influence on stem structure only scarce information of narrower annual growth rings of wood has been published. Therefore, we determined the effect of the presence of the leaf miner infestation on intra-annual cambial activity and on differentiation of conductive tissues. These data were compared with phenological phases and pest activity. Pest feeding resulted in changes in onset, cessation and duration of cambial divisions, and differentiation of secondary xylem. The duration of cambial activity was about a month shorter in heavily infested trees and was connected with premature tree defoliation. Affected trees were characterised by a reduction in cambial divisions and earlier cessation of wood differentiation resulting in narrower wood rings. Furthermore, the infested trees exhibited altered wood structure, with more vessels of smaller diameters, however these changes did not affect its theoretical hydraulic conductivity. Interestingly, pest attack did not influence secondary phloem differentiation. The probable influence of long-term infestation on tree growth and condition was discussed.O

Is the quality of the non-native Douglas-fir wood produced in the Czech forests comparable to native softwoods?

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.O

Xylogenesis and phloemogenesis of Norway spruce in different ages stands at middle altitudinal zone

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.O

Effects of Wood Particles from Deadwood on the Properties and Formaldehyde Emission of Particleboards

The volume of deadwood increases annually because of changes in environmental, climatic, and hydrological conditions. On the other hand, during the last decade, manufacturers of wood-based boards have been facing an acute problem of a shortage of conventional raw materials. The purpose of this study was to evaluate the possibility of using wood particles from deadwood in the production of particleboards. Three-layer particleboards with different content of deadwood particles (0%, 25%, 50%, 75%, 100%) were produced. Conventional urea-formaldehyde (UF) resin was used for gluing the particles. The physical and mechanical properties of the boards, as well as the formaldehyde content in the boards, were determined. In addition, the effect of adding melamine-urea-formaldehyde (MUF) resin to UF adhesive on the properties of the boards was investigated. Replacing conventional sound wood particles with deadwood particles leads to deterioration of the physical and mechanical properties of the boards. The boards from deadwood particles absorb more water and swell more. The bending strength (MOR), modulus of elasticity in bending (MOE), and internal bonding (IB) values for boards with 100% deadwood particles are reduced by 26.5%, 23.1%, and 72.4%, respectively, compared to reference boards from sound wood particles. Despite this, a significant advantage is that boards made from 100% deadwood particles are characterized by 34.5% less formaldehyde content than reference boards made from conventional sound wood. Moreover, adding 3% of MUF resin to UF adhesive increases MOR, MOE, and IB by 44.1%, 43.3%, and 294.4%, respectively.O

Tree-ring width and variation of wood density in Fraxinus excelsior L. and Quercus robur L. growing in floodplain forests

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 kgBULLET OPERATORm-3 and 618.2 kgBULLET OPERATORm-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.O

Auxin (IAA) and soluble carbohydrate seasonal dynamics monitored during xylogenesis and phloemogenesis in Scots pine

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.O

FexIKA method parameters affecting black locust heartwood extraction yield

The influence of certain adjustable parameters (sample property, temperature, and solvent type) on the advanced fexIKA extraction outputs was determined. Extracts were obtained from black locust (Robinia pseudoacacia L.) heartwood and analysed by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). The amount of extract yield remained similar, regardless of the wood particle size, whereas the total amount of phenolic compounds gradually decreased when the particle size increased. The highest amounts of extractives were obtained at higher temperatures, and at 170 and 200oC, a significant influence from the temperature on the chemical composition was noticed. Namely, the phenol and robinetin yields increased, while the rest of the main phenolic compounds were degraded. Additionally, at higher temperatures (170 and 200oC), two newly formed furfural compounds were detected.O

The importance of Arctic driftwood for interdisciplinary global change research (Short Communication / Methodological note)

The Arctic is one of the regions most sensitive to global warming, for which climate and environmental proxy archives are largely insufficient. Arctic driftwood provides a unique resource for research into the circumpolar entanglements of terrestrial, coastal and marine factors and processes – past, present, future. Here, first dendrochronological and wood anatomical insights into 639 Arctic driftwood samples are presented. Samples were collected across northern Norway (n =430) and north-western Iceland (n =209) in 2022. The overall potentials and limitations of Arctic driftwood to improve tree-ring chronologies from the boreal forest, and to reconstruct changes in sea ice extent and ocean current dynamics are discussed. Finally, the role driftwood has possibly played for Arctic settlements in the past hundreds of years is examined

Carbon and nitrogen accumulation in common Alder forest (Alnus glutinosa Gaertn.) in plain of Drava river

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)

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 sequestration1, and its formation in trees consumes around 15% of anthropogenic carbon dioxide emissions each year2. 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 scales3–6. They also suggest that these two growth processes exhibit differential sensitivities to local environmental conditions. Indeed, in the wellwatered 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 factors7 may shift the phase timing of stem size increase and woody biomass production in the future