Heart Wood Research Articles

Chemical characterization of sapwood and heartwood of Fraxinus angustifolia growing in Algeria

The result of this study is the chemical characterization of sapwood (SW) and heartwood (HW) of Fraxinus angustifolia native to Algeria. Lipophilic and hydrophilic extractives were isolated by means of an accelerated solvent extractor (ASE) using hexane and the acetone/water mixture respectively. The acid hydrolysis and methanolysis methods were used to determine cellulose and hemicelluloses contents. The Tappi Standards T 222 and UM 250 allowed Klason and acid-soluble lignin quantification respectively. Alkaline hydrolysis of wood samples followed by HPLC analysis was performed to determine the acetyl groups. The method detailed in TAPPI T 211 (2002) for determining the ash content was used. It was found that the SW and HW of Fraxinus A. had almost similar amounts of the main components, averaging 40.00 wt% cellulose, 28.00 wt% hemicelluloses within 18.00 wt% of xylan, 22.00 wt% lignin, 3% extractives and 0.83 wt% ash. However, the HW contained more triglycerides (0.08 wt%) than the SW (0.02 wt%). On the other hand, mannitol was the most predominant hydrophilic extractive in SW (1.60 wt%) than in HW (1.02 wt%). These findings are useful for practitioners in the paper, biofuel, cosmetics, food, pharmaceutical and chemical industries for the assessment of Fraxinus A. wood chemical treatment parameters.

Wood Extractives of Silver Fir and Their Antioxidant and Antifungal Properties.

The chemical composition of extractives in the sapwood (SW), heartwood (HW), knotwood (KW), and branchwood (BW of silver fir (Abies alba Mill.) was analyzed, and their antifungal and antioxidant properties were studied. In addition, the variability of extractives content in a centripetal direction, i.e., from the periphery of the stem towards the pith, was investigated. The extracts were analyzed chemically with gravimetry, spectrophotometry, and chromatography. The antifungal and antioxidative properties of the extracts were evaluated by the agar well diffusion method and the diphenyl picrylhydrazyl radical scavenging method. Average amounts of hydrophilic extractives were higher in KW (up to 210.4 mg/g) and BW (148.6 mg/g) than in HW (34.1 mg/g) and SW (14.8 mg/g). Extractives identified included lignans (isolariciresinol, lariciresinol, secoisolariciresinol, pinoresinol, matairesinol) phenolic acids (homovanillic acid, coumaric acid, ferulic acid), and flavonoids epicatechin, taxifolin, quercetin). Secoisolariciresinol was confirmed to be the predominant compound in the KW (29.8 mg/g) and BW (37.6 mg/g) extracts. The largest amount of phenolic compounds was extracted from parts of knots (281.7 mg/g) embedded in the sapwood and from parts of branches (258.9 mg/g) adjacent to the stem. HW contained more lignans in its older sections. Hydrophilic extracts from knots and branches inhibited the growth of wood-decaying fungi and molds. KW and BW extracts were better free radical scavengers than HW extracts. The results of the biological activity tests suggest that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties. The results of this study describe BW as a potential source of phenolic extractives in silver fir.

Maclura tinctoria Extracts: In Vitro Antibacterial Activity against Aeromonas hydrophila and Sedative Effect in Rhamdia quelen

Maclura tinctoria is a tree species native from Brazil and rich in phenolic compounds. Since plant antibacterial activity is highly associated with phenolic compound concentration, we aim to evaluate the in vitro antimicrobial activity of different extracts against fish pathogenic bacteria. In addition, some phenolic compounds have central depressant effects and can be useful in aquaculture due to possible sedative and/or anesthetic effects. Four M. tinctoria extracts were extracted separately with ethanol; leaves (LE), bark (BE), heartwood (HE), and the sapwood (SE). In vitro antimicrobial activity was tested against Aeromonas strains at concentrations of 6400 to 3.125 μg/mL. The sedative effect was evaluated for 24 h with 30 and 100 mg/L concentrations. Chemical composition was analyzed by HPLC-DAD-MS. The HE extract had the best MIC (400 µg/mL) and MBC (800 µg/mL) compared to the LE, BE, and SE extracts. LE extract induced deep sedation and the BE, SE, and HE extracts induced light sedation. Additionally, BE, SE, and HE induced a normal behavior without side effects. Polyphenolic compounds with antimicrobial activity and sedative effects were identified mainly in HE. Thus, HE extract is safe and can be used as a sedative for silver catfish.

Comparative metabolomics analysis reveals the color variation between heartwood and sapwood of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook

To reveal the correlation between the metabolites profiles and the wood color variation, metabolomics analysis of heartwood (HW) and sapwood (SW) of Chinese fir at two different ages was performed. The metabolite profiling was obtained using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometer (UPLC/Q-TOF-MS/MS). The results demonstrated that a total of 12,581 metabolites were obtained, of which 850 were annotated to the Human Metabolome Database (HMDB). Principal component analysis (PCA) and orthogonal partial least squares-discriminantion analysis (OPLS-DA) displayed a distinctly variation from HW group and SW group, 21 phenolic compounds including flavonoids, coumarins and derivatives, and stilbenes accumulated most in the HW group, which could be responsible for the darker of HW. As for variation in metabolites between tree ages, the HW and SW from older Chinese fir accumulated greater frequency of secondary metabolites than those from the younger ones. The metabolic pathway enrichment analysis revealed the flavonoid biosynthesis pathway extremely changed between the groups of HW and SW, HW-24Y and HW-19Y, and SW-24Y and SW-19Y, respectively, implying that the identified flavonoid metabolites in this study could clarify the wood color difference between HW and SW in kaihua 3 clone Chinese fir. The results of this study may provide valuable information regarding how the metabolic compositions and the potential of flavonoid pathway alter the wood coloring.

Hinokitiol inhibits RANKL-induced osteoclastogenesis in vitro and prevents ovariectomy-induced bone loss in vivo

Osteoporosis is a metabolic bone-loss disease characterized by abnormally excessive osteoclast formation and bone resorption. Identification of natural medicines that can inhibit osteoclastogenesis, bone resorption, and receptor activator of nuclear factor-κB ligand (RANKL)‐induced signaling is necessary for improved treatment of osteoporosis. In this study, hinokitiol, a tropolone-related compound extracted from the heart wood of several cupressaceous plants, was found to inhibit RANKL-induced osteoclast formation and bone resorption in vitro. Hinokitiol inhibited early activation of the ERK, p38, and JNK–MAPK pathways, thereby suppressing the activity and expression of downstream factors (c‐Jun, c‐Fos, and NFATC1). Consistent with the above in vitro findings, hinokitiol treatment protected against ovariectomy-induced bone loss in vivo. Collectively, our results imply that hinokitiol can potentially serve as an effective agent for treating osteoclast-induced osteoporosis.

Amelioration of diabetic nephropathy with extracts of Pterocarpus santalinus heart wood and Brassica nigra seeds via regulation of insulin resistance and modulation of genes in streptozotocin induced diabetic rats

The current study was designed to investigate the possible effects of aqueous extract of Pterocarpus santalinus heart wood and Brassica nigra seeds on streptozotocin (STZ) induced diabetic rats. Adult male albino rats of 24 numbers were used in this study and were divided into four groups, each group contain 6 animals. For induction of diabetes rats were received STZ (65 mg/kg body weight). After STZ induction the remaining three groups were split as follow: group 2 served as diabetic untreated group, group 3 served as diabetic group treated with aqueous Pterocarpus santalinus extract and group 4 served as diabetic group treated with aqueous Brassica nigra extract. STZ administration produced significant increase in serum glucose, HbA1c, Homeostatic Model Assessment insulin resistance (HOMA-IR), lipids, creatinine and urea levels; also, significant decrease in insulin level, Homeostatic Model Assessment insulin sensitivity (HOMA-IS), Quantitative Insulin Sensitivity Check Index (QUICKI) and Glomerular filtration rate (GFR). At molecular level, STZ administration produced significant up-regulation in the mRNA of Thioredoxin-interacting protein (TXNIP), The Nod-like receptor protein 3(NLRP3) and inflammasome and Apoptosis-enhancing nuclease (AEN). The effects of aqueous extracts of P. santalinus wood and B. nigra seeds were evidenced by significant decreased in serum levels of glucose, HbA1c, lipids, creatinine and urea as well as significant increase in insulin, HDL and GFR level. Further treatment with aqueous extracts of Pterocarpus santalinus and Brassica nigra down-regulated the mRNA of TXNIP, NLRP3 and AEN. The results of this study concluded that aqueous extracts of P. santalinus and B. nigra reduced the effects of STZ- induced diabetes and they can be used for the treatment of diabetes and its complication.

Dimensional Stability of Waterlogged Scots Pine Wood Treated with PEG and Dried Using an Alternative Approach

Low-intensity drying is widely believed to protect waterlogged archeological wood against the adverse effects of dimensional alteration and cracking. However, slow drying generates substantial costs for the conservation process. This study compares the effects on conservation of highly-degraded sapwood (SW) and slightly-degraded heartwood (HW) from waterlogged archeological Scots pine wood treated with polyethylene glycol either as a mixture of polyethylene glycol (PEG) 400/4000 or PEG 2000 solution and air-dried using different approaches. The reference air-drying approach, using gradually decreasing air relative humidity (RH), i.e., 96, 86, 75, 66, and finally 44% (multi-stage schedule), was compared to an alternative approach, using constant RH of 44% (single-stage schedule). The Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the decomposition of hydrophilic chemical wood components and revealed differences in the degree of degradation of waterlogged SW and HW. The drying time of PEG-treated waterlogged wood air-dried using a one-stage schedule was shorter compared to the drying time using multi-stage drying. Multivariate analysis (ANOVA) revealed that the drying schedule used after impregnation of waterlogged wood with PEG can have a beneficial effect on wood hygroscopicity and dimensional stability. The drying schedule significantly affected the equilibrium moisture content (EMC) of SW and HW and reduced tangential (ST) shrinkage of SW. These results show the positive effect of the single-stage alternative drying approach on the dimensional stability of highly-degraded Scots pine SW impregnated with PEG 2000. In the case of slightly-degraded HW, the drying approach did not affect wood preservation. These results can be useful for the conservation of highly-degraded waterlogged Scots pine wood.

Pretreatment of Cellulose from Sugarcane Bagasse with Xylanase for Improving Dyeability with Natural Dyes.

In this study, cellulose was obtained from sugarcane bagasse (SCB) and treated with xylanase to remove residual noncellulosic polymers (hemicellulose and lignin) to improve its dyeability. The cellulose fibers were dyed with natural dye solutions extracted from the heart wood of Ceasalpinia sappan Linn. and Artocarpus heterophyllus Lam. Fourier-transform infrared (FTIR) spectroscopy, Raman analysis, and whiteness index (WI) indicated successful extraction of cellulose by eliminating hemicellulose and lignin. The FTIR analysis of the dyed fibers confirmed successful interaction between natural dyes and cellulose fibers. The absorption (K) and scattering (S) coefficient (K/S) values of the dyed fibers increased in cellulose treated with xylanase before dyeing. Scanning electron microscopy (SEM) analysis showed that the surface of alkaline-bleached fibers (AB-fibers) was smoother than alkaline-bleached xylanase fibers (ABX-fibers), and the presence of dye particles on the surface of dyed fibers was confirmed by energy-dispersive spectrometry (EDS) analysis. The X-ray diffraction (XRD) revealed a higher crystallinity index (CrI), and thermal gravimetric analysis (TGA) also presented higher thermal stability in the dyed fibers with good colorfastness to light. Therefore, xylanase treatment and natural dyes can enhance dyeability and improve the properties of cellulose for various industrial applications.

Beneficial effect of phospholipase A2 group IIA inhibitors from Acacia suma in obesity: an in silico and in vitro study

Acacia suma Roxb. (Fabaceae) is Ayurvedic medicine distributed in Karnataka, Bengal and Bihar region. Phytoconstituents of A. suma were retrieved from ChEIB databases and queried for phospholipase A2 group IIA inhibitors. The present study is an effort to find out a novel therapeutic solution for the management of obesity disorders. Out of 29 reported compounds three were identified in modulating phospholipase A2 group IIA inhibitor their drug likeness score andprobable gene expression was identified. Docking study was performed using autodock4.0 to predict binding affinity of phytoconstituents with phospholipase A2 group IIA inhibitor and compared with clinically proven drug ‘Orlistat’ as lipase inhibitor. The respected pathway to show networking between phytochemicals and target were analyse by kyoto encyclopedia of genes and genomes pathway analysis for regulated genes. Further, in silico findings were validated for hydroalcoholic extract of A. suma by in vitro lipase inhibition assay. Molecular docking result revealed the presence of three flavonoid compounds for lipase inhibition activity namely: (1) (5S,7R,8R,9R,10S)-(−)-7,8–seco-7,8–oxacassa-13,15-diene-7,17-diol (2) Fisetinidol-(4α,6)-gallocatechin and (3) Quercetin4′-O-α-l-rhamnopyranosyl-3-O-β-d-allopyranoside. However, Quercetin4′-O-α-l-rhamnopyranosyl-3-O-β-d-allopyranoside was predicted to possess the highest docking score i.e. − 7.6 kcal/mol with phospholipase A2 group IIA. The in vitro findings revealed significant anti-lipase activity with IC50 value − 46.07 μg/ml. Hence, the in silico and in vitro approaches has presented strong binding affinity and significant lipase inhibition activity respectively which supports anti-obesity potential of heart wood hydroalcoholic extract of A. suma.

Differential Gene Profiling of the Heartwood Formation Process in Taiwania cryptomerioides Hayata Xylem Tissues.

Taiwania (Taiwania cryptomerioides) is an important tree species in Taiwan because of the excellent properties of its wood and fascinating color qualities of its heartwood (HW), as well as the bioactive compounds therein. However, limited information is available as to the HW formation of this species. The objective of this research is to analyze the differentially expressed genes (DEGs) during the HW formation process from specific Taiwania xylem tissues, and to obtain genes that might be closely associated with this process. The results indicated that our analyses have captured DEGs representative to the HW formation process of Taiwania. DEGs related to the terpenoid biosynthesis pathway were all up-regulated in the transition zone (TZ) to support the biosynthesis and accumulation of terpenoids. Many DEGs related to lignin biosynthesis, and two DEGs related to pinoresinol reductase (PrR)/pinoresinol lariciresinol reductase (PLR), were up-regulated in TZ. These DEGs together are likely involved in providing the precursors for the subsequent lignan biosynthesis. Several transcription factor-, nuclease-, and protease-encoding DEGs were also highly expressed in TZ, and these DEGs might be involved in the regulation of secondary metabolite biosynthesis and the autolysis of the cellular components of ray parenchyma cells in TZ. These results provide further insights into the process of HW formation in Taiwania.

A comparative metabolomics analysis of the components of heartwood and sapwood in Taxus chinensis (Pilger) Rehd.

Taxus chinensis is a well-known gymnosperm with great ornamental and medicinal value. Its purple red brown heartwood (HW) has many attributes such as straight texture, high density, mechanical strength, rich elasticity and corrosion resistance that is highly prized commercially. T. chinensis sapwood (SW), in comparison, lacks these important traits. At present, little is known about the differences of metabolites between the SW and HW in T. chinensis. Widely targeted metabolic profiling was performed to analyze the metabolic profiles of HW and SW in T. chinensis using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-EI-MS). A total of 607 metabolites were detected in HW and SW. Among them, 146 metabolites were significantly higher, and 167 metabolites significantly lower, in HW as compared to SW. These differential metabolites were mainly involved in metabolic pathways and biosynthesis of secondary metabolites, such as flavonoids, flavone and flavonol, phenylpropanoids and antibiotics. Moreover, 71 flavonoids and isoflavones were found to be significantly different between HW and SW. Our results show the difference of components between the HW and SW, which has potential significance to further elucidate the mechanism of HW color formation. The results will provide insight into the metabolites associated with wood color formation and useful information for understanding the metabolites associated with wood quality.

Folklore poly herbal extract: How is it implicated in the control of seizure susceptibility?

Epilepsy is a chronic neurological disorder characterized by anenduring predisposition to generate seizures, may be associated with emotional and cognitive dysfunction. The study was to examine the antiepileptic potential of folklore polyherbal extract (PHE) which consists ofPterocarpus Santalinus, Mesua Ferrea. Linn. and Vetiveria zizanioides in experimental models of epilepsy using swiss albino mice. Ethanolic extract of three driedpowders taken from stamens of Mesua Ferrea. Linn. (MF), heart wood of Pterocarpus Santalinus (PS) and roots of Vetiveria zizanioides (VZ) were evaluated against Maximum Electroshock (MES) and Strychnine Induced Convulsions (SIC). The preliminary qualitative phytochemical analysis of PHE showed presence of alkaloids, flavonoids, steroids, saponins, triterpenoids and glycosides. The extract was subjected to behavioral parameters, anxiolytic, locomotor activity and motor co-ordination activity and also estimated biogenic amines in the brain. The PHE was showed anticonvulsant activity against MES-induced convulsion; tonic extension phase was abolished and offered a significant inhibition against SIC. PHE exhibited significantly increased the brain levels of serotonin, dopamine, noradrenaline and monoamine. PHE shows significant effect in behavioral activities at thedose of 500 mg/kg when compared to standard drug phenytoin (25mg/kg).The PHE contains flavones and saponins which may responsible for its CNS activity. The present study indicates the PHE possess the anti-epileptic activity by different mechanisms. Future studies are required to know the molecular mechanism of actions of PHE. Effect of Polyherbal extract on maximal electroshock induced seizures in miceTabled 1GroupsDuration of HLTE (sec)Quantal protection% protectionControl15.67±0.514/666.67Polyherbal extract14.33±0.81*5/683.33Phenytoin (25mg/kg)15.33±0.51*6/6100 Open table in a new tab

Muntingia Calabura: Potential Source of Pharmacologically Active Substances

Plants are generally measured as origin of natural drugs and are extensively used in herbal formulations. Muntingia calabura (Muntingeaceae) is indigenous to Central America and Southern Mexico It is abundantly disseminated throughout Asian countries especially in India. The present research was done on the isolation, pharmacological study of the isolated compounds derived from root heart wood and bark of the root of Muntingia calabura. For this study, six compounds were taken into account and later it was divided into two categories as flavonoids and chalcones. The isolated compounds were further screened for their attributed pharmacological traits. All the compounds screened noticed to possess significant medicinal properties.

In Vitro and In Vivo Evaluation of the Anticancer and Anti-inflammatory Activities of 2-Himachelen-7-ol isolated from Cedrus Libani

Cedrus libani is a majestic evergreen tree native to the Mediterranean mountains of Lebanon, Syria and Turkey. In this study, the tree heart wood was extracted using hexane to produce C. libani oil extract (CLOE) as a dark oil. GCMS analysis of CLOE identified up to 30 compounds whereby 2-himachalen-7-ol (7-HC) was the most abundant (40%). 7-HC was isolated using column chromatography and the identity of the white crystalline solid was confirmed via NMR spectroscopy and X-Ray Crystallography. 7-HC demonstrated potent cytotoxic activity against several human cancer cell lines including brain (SF-268, IC50 8.1 μg/mL) and colon (HT-29, IC50 10.1 μg/mL; Caco-2, IC50 9.9 μg/mL) with ovarian (Sk-OV-3, IC50 > 50 μg/mL) cells being the most resistant. However, while HT-29 displayed resistance to Cisplatin, 7-HC was 8–10 folds more potent. Co-treatment with 7-HC and Cisplatin showed a significant synergistic anti-proliferative effect against SF-268, HT-29 and Caco-2 cells. 7-HC also exhibited significant anti-inflammatory effect in formalin-induced paw edema in rats. Western blot analysis revealed that 7-HC displayed dose dependent inhibition of LPS-induced COX-2 protein expression in isolated rat monocytes. The present study demonstrates that 7-HC possesses promising anticancer and anti-inflammatory activities, and may serve as a lead molecule in cancer therapy.

Anti-HIV-1 activity and safety profile of a polyherbal gel formulation as a candidate microbicide

Microbicides represent one of the promising options for the prevention of sexually transmitted HIV infection. Medicinal plants have a long history of use to provide treatment against many diseases. In this regard, polyherbal aqueous gel formulation comprising 50% ethanolic extract prepared from the heart wood of Acacia catechu, leaves of Lagerstroemia speciosa, fruits of Aegle marmelos, Phyllanthus emblica and Terminalia chebula using carbopol 974 P NF polymer has been prepared. The gel formulation showed significant anti-HIV-1 activity against both CXCR4 tropic (HIV-1NL4.3) and CCR5 tropic (HIV-1NLAD8) viruses with IC50 values of 58.17 ± 4.4 and 63.54 ± 6.8 μg/ml respectively. It also showed significant inhibition of HIV-1 reverse transcriptase (p = 0.004), protease (p = 0.014), and integrase (p = 0.018) enzymes activity as compared to gel base. The gel formulation did not show any adverse effect on the viability of the vaginal lactobacilli, human vaginal keratinocytes (Vk2/E6E7), and the monolayer formed by Caco-2 cells. Furthermore, no significant changes in the secretion of pro-inflammatory cytokines such as IL-1β, IL-6, IL-8, IL-10, IL-12p70, and TNF from the gel formulation treated Vk2/E6E7 cells were observed as compared to cells treated with gal base or medium control. Gel formulation did not show any significant increase in mutagenic index using Salmonella typhimurium. Gel formulation stored at either 30 ± 2 °C or 40 ± 2 °C was stable for 6 months for anti-HIV-1 activity. In conclusion, the polyherbal gel formulation reported herein having potent anti-HIV-1 activity and with limited safety profile may be a promising candidate as an herbal microbicide.

Wood Density Variations of Legume Trees in French Guiana along the Shade Tolerance Continuum: Heartwood Effects on Radial Patterns and Gradients

Increasing or decreasing wood density (WD) from pith to bark is commonly observed in tropical tree species. The different types of WD radial variations, long been considered to depict the diversity of growth and mechanical strategies among forest guilds (heliophilic vs. shade-tolerant), were never analyzed in the light of heartwood (HW) formation. Yet, the additional mass of chemical extractives associated to HW formation increases WD and might affect both WD radial gradient (i.e., the slope of the relation between WD and radial distance) and pattern (i.e., linear or nonlinear variation). We studied 16 legumes species from French Guiana representing a wide diversity of growth strategies and positions on the shade-tolerance continuum. Using WD measurements and available HW extractives content values, we computed WD corrected by the extractive content and analyzed the effect of HW on WD radial gradients and patterns. We also related WD variations to demographic variables, such as sapling growth and mortality rates. Regardless of the position along the shade-tolerance continuum, correcting WD gradients reveals only increasing gradients. We determined three types of corrected WD patterns: (1) the upward curvilinear pattern is a specific feature of heliophilic species, whereas (2) the linear and (3) the downward curvilinear patterns are observed in both mid- and late-successional species. In addition, we found that saplings growth and mortality rates are better correlated with the corrected WD at stem center than with the uncorrected value: taking into account the effect of HW extractives on WD radial variations provides unbiased interpretation of biomass accumulation and tree mechanical strategies. Rather than a specific feature of heliophilic species, the increasing WD gradient is a shared strategy regardless of the shade tolerance habit. Finally, our study stresses to consider the occurrence of HW when using WD.

Pruning Effects on the Health of Indian Sandalwood (<i>Santalum album</i> Linn) in Agroforestry Conditions of South India

Surveys in south India revealed that Santalum album Linn. is commonly grown with forest trees and horticultural and agricultural crops. As a silvicultural practices in cultivation of S. album though pruning is not recommended many farmers follow the practice of regular pruning there by adversely affecting the health of trees. Severely pruned trees were found losing their erectness and bending indicating that pruning causes change, disorder and affect many physiological functions resulting in deterioration of overall tree health. The wounds caused by pruning sever tissue connections and enhances the infection of decay fungi. It attracts the infestation of insect pests particularly the stem and wood borers. The incidence of bark caterpillar Indarbela quardinotata Walker, red stems borer Zeuzera coffeae Nietn. and heart wood borer Aristobia octofasciculata Aurivillius was found significantly higher in pruned plantations compared un-pruned plantations. The heartwood loss ranging from 22.6 to 34.5% was observed during extraction and this loss might be attributed due to the adverse effect of pruning and other mechanical injuries inducing infection of decay fungi and infestation of stem borers in young plantations of S. album. Hence, to avoid not only the pruning but also any silvicultural practices that cause injury to sandalwood are recommended for its healthy growth and thereby to obtain desirable returns.

ДИНАМІЧНИЙ МОДУЛЬ ПРУЖНОСТІ ХВИЛЯСТО-ЗАВИЛЬКУВАТОЇ ДЕРЕВИНИ ABIES ALBA MILL.

Досліджено відмінності динамічного модуля пружності, коефіцієнта затухання та швидкості звуку хвилясто-завилькуватої деревини порівняно з прямоволокнистою деревиною ялиці білої. Графічно наведено варіацію досліджуваних показників у межах радіуса та висоти стовбура. У межах радіуса стовбура із хвилясто-завилькуватою структурою можна виділити два класи якості деревини, а саме: перший – периферійна деревина (40 % радіуса стовбура) та другий – центральна (ядрова) деревини. Структурне розміщення деревного волокна, зокрема хвилясто-завилькувате, істотно визначає фізико-механічні характеристики деревини та їх варіацію. Коефіцієнт затухання деревини змінюється: від 6 до 10 для хвилясто-завилькуватої деревини; від 12 до 14 для прямоволокнистої деревини. Встановлено прямолінійну залежність першого порядку між динамічним модулем пружності та об'ємною масою деревини. Збільшення об'ємної маси прямоволокнистої деревини зумовлює збільшення модуля пружності та описується рівнянням прямої (R²=0,69…0,72). Прямолінійна залежність між динамічним модулем пружності та щільністю хвилясто-завилькуватої деревини є інверсійною. Динамічний модуль пружності прямоволокнистої деревини знаходиться в межах від 5921 до 12995 Н∙мм-2, а хвилясто-завилькуватої деревини – від 5053 до 12393 Н∙мм-2.

Micro-morphological, physical and thermogravimetric analyses of waterlogged archaeological wood from the prehistoric village of Gran Carro (Lake Bolsena-Italy)

Abstract Oak disks from pile dwellings of the prehistoric site of Gran Carro (lake Bolsena, Italy) were analysed in order to estimate wood degradation. Micro-morphological observations showed that the microbial decay could be mainly attributed to erosion bacteria. The most important physical properties, i.e. Maximum Water Content (MWC), Residual basal Density (RDb), and the calculation of the Lost Wood Substance (LWS) highlighted that heartwood (HW) was moderately preserved, with MWC values slightly higher or comparable to that of recent oak, whereas sapwood (SW) was very degraded. Thermogravimetric analysis (TGA) was tested as an alternative method for the chemical characterisation of archaeological wood. The TGA profiles were critically discussed taking into account the results of the physical and micro-morphological analyses. Potentialities and drawbacks of TGA were underlined.

DO INHERENT AND INDUCED MIOMBO TREE TRUNK MACRO-STRUCTURAL CHARACTERISTICS INFLUENCE REGENERATION AFTER CUTTING FOR CHARCOAL PRODUCTION?

This study assessed the influence of tree trunk macro-structural characteristics on species’ potential for regeneration after cutting for charcoal production. The main objective of the study was to determine regeneration responses of species harvested for charcoal production. Diametre of the stump, bark thickness, cambium and heart wood thickness, rough and smooth bole textural groups and others were examined. Such information was necessary for regulating harvesting systems and influencing policy adjustments regarding the harvesting strategies for trees used in charcoal production. Ten transects 100 metres long each were placed parallel to each other at a minimum interval of 30 metres apart in areas where trees had been cut for charcoal in the last four years (2013 – 2017). Along each transect, five 20 m x 20 m plots were set and all tree stumps inside the plot identified and examined. The major objectives were to determine the influence of structural characteristics on the species’ potential to regenerate. Bark thickness for instance, was considered to be an important stem charesctristic as it protects the living stem tissue particulalry against wildfire. Results obtained showed that the hypotheis inititally advanced that in addition to soil moisture and nutrients, macro-structural components of each tree species influenced regeneration was false. It was initially thought that larger proportions of tree trunk macro-structural characteristics would yield higher and faster regeneration and vice versa but this was found to be false. All species with varying macrostructural characteristics successfully regenerated. The results were therefore, inconclusive and further research is required to be conducted in different agro-ecological zones to investigate other factors that may be critical in influencing regeneration. Factors such as root structure and root depth, soil structure and moisture retention capacity, level of accumulation of chemical compounds such as resins, phenols, and terpenes between species and age groups or stem size require detailed investigation. With regard to the survival of saplings after regeneration, it was recommended that formulation and implementation of a community-based fire management plan would enhance the survival of saplings. Good fire management practices together with soil moisture and fertility promote the ecological forest restoration of miombo woodlands.