Распределение механических свойств древесины лиственных пород в годовых кольцах, выявленных методом сканирующего наноиндентирования

The paper presents the results of mechanical properties scanning by means of nanoindentation across the annual growth rings of deciduous trees wood, small-leaved lime (Tilia cordata) and common oak (Quercus robur) in particular. Significant variations in microhardness H and Young’s modulus E radial dependencies have been found for any of the studied species. Results can be useful 1) to amend the understanding the nature of macromechanical properties of various wood species and to reveal the details of their formation depending upon microstructural characteristics, 2) to optimize the technologies of growing, reinforcement and subsequent usage of the wood, 3) to develop new independent methods in dendrochronology and dendroclimatology

Reconstruction of historic fossil CO₂ emissions using radiocarbon measurements from tree rings

<p>This project aims to reconstruct historic fossil fuel derived CO₂ (CO₂ff) emissions from two closely located point sources in Taranaki, New Zealand. The Vector gas processing plant and the Ballance agri-nutrients ammonia urea plant have combined emissions of ~0.16 TgC yr⁻¹ since 1970 and 1982 respectively. Previous work found 2–5 ppm CO₂ff in short term integrated samples collected 600m downwind of the Vector plant. This study extends the dataset back 30 years using radiocarbon measurements in tree rings. Trees incorporate CO₂ from the local atmosphere into their annual growth rings. Measurements of ¹⁴C in polluted and clean air trees were compared to the Baring Head Δ¹⁴CO₂ atmospheric record. As CO₂ff emissions are devoid of ¹⁴C addition of CO₂ff will cause a decrease in ¹⁴C directly related to the amount of CO₂ff present. Trees growing immediately downwind of the Vector plant and from clean air locations in Taranaki and Baring Head Wellington, were cored and cut into one year growth increments. Two cellulose preparation methods were tested to confirm effectiveness at removing mobile extractive components and lignin. Radiocarbon and stable isotope results showed that the ANSTO method was more effective than the Rafter method. The clean air trees compare well with the Baring Head atmospheric record whereas trees growing downwind of the Vector plant demonstrate lower ¹⁴C content consistent with CO₂ff addition. Historic CO₂ff emissions were reconstructed for the polluted trees, with 1–3ppm of CO₂ff in the Luscombe chestnut tree and 4–7 ppm CO₂ff in the Vector pine tree. CO₂ff observations were compared with reported emissions from the Vector and Ballance plants. Observed CO₂ff increased by 10% in the Vector pine tree for the period 1994–2012 relative to pre-1994 levels, whereas combined CO₂ff emissions increased by 64%. No increase was observed in the Luscombe chestnut tree for the same time period. Meteorological analysis was performed to assess the relative contribution of CO₂ff from the sources to the trees. It is proposed that the trend observed in the Vector pine is due to the dominance of emissions from the Ballance plant and a relatively minor contribution from the Vector plant.</p>

Reconstruction of historic fossil CO₂ emissions using radiocarbon measurements from tree rings

<p>This project aims to reconstruct historic fossil fuel derived CO₂ (CO₂ff) emissions from two closely located point sources in Taranaki, New Zealand. The Vector gas processing plant and the Ballance agri-nutrients ammonia urea plant have combined emissions of ~0.16 TgC yr⁻¹ since 1970 and 1982 respectively. Previous work found 2–5 ppm CO₂ff in short term integrated samples collected 600m downwind of the Vector plant. This study extends the dataset back 30 years using radiocarbon measurements in tree rings. Trees incorporate CO₂ from the local atmosphere into their annual growth rings. Measurements of ¹⁴C in polluted and clean air trees were compared to the Baring Head Δ¹⁴CO₂ atmospheric record. As CO₂ff emissions are devoid of ¹⁴C addition of CO₂ff will cause a decrease in ¹⁴C directly related to the amount of CO₂ff present. Trees growing immediately downwind of the Vector plant and from clean air locations in Taranaki and Baring Head Wellington, were cored and cut into one year growth increments. Two cellulose preparation methods were tested to confirm effectiveness at removing mobile extractive components and lignin. Radiocarbon and stable isotope results showed that the ANSTO method was more effective than the Rafter method. The clean air trees compare well with the Baring Head atmospheric record whereas trees growing downwind of the Vector plant demonstrate lower ¹⁴C content consistent with CO₂ff addition. Historic CO₂ff emissions were reconstructed for the polluted trees, with 1–3ppm of CO₂ff in the Luscombe chestnut tree and 4–7 ppm CO₂ff in the Vector pine tree. CO₂ff observations were compared with reported emissions from the Vector and Ballance plants. Observed CO₂ff increased by 10% in the Vector pine tree for the period 1994–2012 relative to pre-1994 levels, whereas combined CO₂ff emissions increased by 64%. No increase was observed in the Luscombe chestnut tree for the same time period. Meteorological analysis was performed to assess the relative contribution of CO₂ff from the sources to the trees. It is proposed that the trend observed in the Vector pine is due to the dominance of emissions from the Ballance plant and a relatively minor contribution from the Vector plant.</p>

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.

A Guarneri violin in the attic: the power of dendrochronology for analysing musical instruments

Dendrochronology is the science that dates wooden artefacts by measuring annual growth rings visible in the wood. And, in the case of musical instruments, the method is non-invasive. In addition, dendrochronology can also help to identify the wood’s provenance and to supply information on how the soundboard was made, giving details of ring width and regularity. This study also demonstrates the effectiveness of dendrochronology in attributing a musical instrument to an important luthier. It deals with a privately owned violin, whose date and origin had previously remained uncertain, despite various attempts to authenticate, at least, its technical and stylistic characteristics. The outermost tree-ring of the instrument’s soundboard was dendrochronologically dated to the year 1696 and attributed, with certainty, to the Italian luthier Giuseppe Guarneri filius Andreae, father of the famous Bartolomeo Giuseppe Guarneri "del Gesù". Thanks to dendrochronology, in this way, a twin of an already existing violin has been identified that was made by the same luthier. Both violins are identical in construction, having the same veining and dimensions, and the wood from the same tree was used in all parts, including the soundboard. Dendrochronology has, thus, been proven to be an extremely useful method, which has transformed a violin of uncertain value into a museum piece.

Influence of Age on the Strength of Different Species of Timber

Timbers are used as structural members in various areas of construction works. Hence the knowledge of properties of wood especially strength and factors affecting the strength of timber is very important. This study was conducted to determine the effect of age on the structural strength of timber. The wood species studied are Iroko (Chlorophora excelsa), Nigerian Mahogany (Khaya anthotheca) and Ita (Celtis mildbraedii). The age of timber were determined by counting the number of annual growth rings, which is the combination of early wood and late wood and samples of different ages of timber, were obtained by personal visit to the forest where fresh timber was cut. The samples obtained were machined and trimmed to standard size with respect to BS 373 1957 (imprint 1999), 20mm X 20mm X 60mm for the determination of maximum compressive strength parallel to grain (MCS//), 20mm X 20mm X 20mm for static shear strength and 20mm X 20mm X 300mm to determine the bending strength. The samples obtained were carried to the laboratory at Forestry Research Institutes of Nigeria (FRIN) in Ibadan for testing using Instron Tensiometer machine. SPSS was used to analyze the relationship between strength and age of timber. The result obtained showed that the maximum compressive and Shear strength for Iroko, were at 120years, whereas it has maximum bending strength at 70years. Nigeria Mahogany and Ita has maximum compressive, bending and shear strength at 80 years, and 70 years respectively and among the three timber samples Ita is better in compression and shear strength and iroko is better in bending strength. It was concluded that age of timber has significant influence on timber strength

MECHANICAL PROPERTIES OF POLISH-GROWN PINUS SYLVESTRIS L. STRUCTURAL SAWN TIMBER FROM THE BUTT, MIDDLE AND TOP LOGS

The research consisted in testing Polish sawn timber dedicated for construction applications made of pines (Pinus sylvestris L.) that grew in the Silesian Forestry Region, taking into account three parts of the log: butt, middle and top. The boards had the same cross section, a nominal thickness of 40 mm and width of 138 mm, typical for Polish structural timber. The mean nominal length of the boards under research amounted to 3500 mm. Each set was composed of 70 boards. Before the tests, boards were dried in an industrial drier until reaching the moisture content of 12%, and they were planed on 4 sides. First of all, the sawn timber was graded into strength classes, and their dynamic modulus of elasticity (MOE_dyn) was tested with a non-destructive method, with the use of a portable MTG device. The next step consisted in a bending test with four points of support, according to the EN 408 standard, and with the use of the TiraTest 2300 machine, in order to determine the global modulus of elasticity (MOE_EN-408) and the static bending strength, also referred to as modulus of rupture (MOR). Finally, the average growth ring width was determined for each board (PN-D-94021), as well as wood density according to EN-408. The hereby paper presents the test results for all the tested sawn timber boards, taking into account the part of log that each board came from: butt, middle or top. The hereby paper presents the influence of density on the mechanical properties of wood, taking into account the location on the round timber. The analysis does not include the influence of the width of annual growth rings and the proportion of latewood on the wood properties under research.

Climate fluctuations drive the recruitment and growth of temperate grassland plants

Recent climate warming is associated with the increasing magnitude and frequency of extreme events, including heatwaves and drought periods worldwide. Such events can have major effects on the species composition of plant communities, hence on biodiversity and ecosystem functioning. Here we studied responses of Central European dry grassland plants to fluctuating temperature and precipitation over the last thirty years with monthly temporal resolution. We assessed the seasonal and annual dynamics of plant recruitment and growth based on the analysis of annual growth rings from the root collar. Although most studies so far applied such methods to trees and shrubs, we focused on typical grassland plants, two forbs and two chamaephytes. We related the recruitment and annual growth to monthly and annual precipitation, temperature and aridity between 1991 and 2019. We revealed species-specific responses, namely the (i) recruitment of deep-rooted, heavy-seeded species was positively affected by precipitation in both late winter-early spring and summer, whereas recruitment of shallow-rooted, light-seeded species was weakly influenced by climate fluctuations; (ii) growth of shallow-rooted species was more adversely affected by high summer temperature and drought than the growth of deep-rooted species. The population age structure of all the studied species was affected by the climate of the past decades. Most individuals established in the wet period of the 2000s, fewer in the precipitation-poorer 1990s, and the establishment was considerably reduced in the dry and warm period of the 2010s. Our findings indicate that the change towards warmer and drier climate has a profound effect even on drought-adapted ecosystems such as temperate dry grasslands. However, plant responses to various climatic extremes are species-specific, depending on their characteristics, such as life form or rooting depth. Consequently, the ongoing and anticipated climate warming will likely result in complex changes in species composition and other ecosystem properties of temperate grasslands