Durability Of Heartwood Research Articles

Re-evaluation of the Assessment Done by FFPRI to Elucidate the Natural Durability of Heartwood

Re-evaluation of the Assessment Done by FFPRI to Elucidate the Natural Durability of Heartwood

Genomic selection reveals hidden relatedness and increased breeding efficiency in western redcedar polycross breeding.

Western redcedar (WRC) is an ecologically and economically important forest tree species characterized by low genetic diversity with high self‐compatibility and high heartwood durability. Using sequence capture genotyping of target genic and non‐genic regions, we genotyped 44 parent trees and 1520 offspring trees representing 26 polycross (PX) families collected from three progeny test sites using 45,378 SNPs. Trees were phenotyped for eight traits related to growth, heartwood and foliar chemistry associated with wood durability and deer browse resistance. We used the genomic realized relationship matrix for paternity assignment, maternal pedigree correction, and to estimate genetic parameters. We compared genomics‐based (GBLUP) and two pedigree‐based (ABLUP: polycross and reconstructed full‐sib [FS] pedigrees) models. Models were extended to estimate dominance genetic effects. Pedigree reconstruction revealed significant unequal male contribution and separated the 26 PX families into 438 FS families. Traditional maternal PX pedigree analysis resulted in up to 51% overestimation in genetic gain and 44% in diversity. Genomic analysis resulted in up to 22% improvement in offspring breeding value (BV) theoretical accuracy, 35% increase in expected genetic gain for forward selection, and doubled selection intensity for backward selection. Overall, all traits showed low to moderate heritability (0.09–0.28), moderate genotype by environment interaction (type‐B genetic correlation: 0.51–0.80), low to high expected genetic gain (6.01%–55%), and no significant negative genetic correlation reflecting no large trade‐offs for multi‐trait selection. Only three traits showed a significant dominance effect. GBLUP resulted in smaller but more accurate heritability estimates for five traits, but larger estimates for the wood traits. Comparison between all, genic‐coding, genic‐non‐coding and intergenic SNPs showed little difference in genetic estimates. In summary, we show that GBLUP overcomes the PX limitations, successfully captures expected historical and hidden relatedness as well as linkage disequilibrium (LD), and results in increased breeding efficiency in WRC.

Cellular level chemical changes in Scots pine heartwood during incipient brown rot decay

The heartwoods of many wood species have natural resistance to wood decay due to the accumulation of antifungal heartwood extractives. The natural durability of heartwoods has been extensively investigated, yet very little information is available on the initiation of heartwood decay. This experiment examined the onset of Rhodonia placenta brown rot decay in Scots pine heartwood in order to identify the key changes leading to heartwood decay. An imaging approach based on Raman imaging and multivariate image analysis revealed that the degradation of heartwood began in the innermost cell wall layers and then spread into the remaining cell walls and the middle lamella. Pinosylvins were extensively degraded in the cell walls, middle lamella and extractive deposits, while unidentified material most likely consisting of hemicelluloses and/or lipophilic extractives was removed from the inner cell wall layers. Changes similar to inner cell wall degradation were seen in the remaining cell walls in more advanced decay. The results indicate that the key change in incipient heartwood decay is the degradation of antifungal heartwood extractives. The inner cell wall degradation seen in this experiment may serve a nutritive purpose or facilitate the penetration of degradative agents into the cell walls and middle lamella.

Understanding the natural durability of some African tropical heartwoods toward Pycnoporus sanguineus and Antrodia sp.: lignin structure and cellulose morphology control

The natural durability of the heartwoods from Testulea gabonensis Pellgr. (T. gabonensis), Julbernardia pellegriniana (J. pellegriniana), Aucoumea klaineana Pierre (A. klaineana), and Tieghemella africana Pierre (T. africana) widely used for windows, door frames, frameworks, closets, cupboards and plywood in the Congo Basin or other countries in the world were studied. The samples were exposed to Pycnoporus sanguineus (P. sanguineus) and Antrodia sp. Factors such as extracts toxicity, lignin syringyl to guaiacyl (S/G) ratio, cellulose crystalline, and fibers morphology which control the resistance of the wood toward white- and brown-rot fungi were investigated. Unextracted woods displayed a strong natural durability against P. sanguineus compared to Antrodia sp., except for A. klaineana which didn’t show significant difference concerning its durability against the white- or the brown-rot fungus. Unextracted heartwoods from T. gabonensis and T. africana were very durable against P. sanguineus; they contain extracts with strong toxicity toward that white-rot fungus. However, A. klaineana and J. pellegriniana heartwoods were moderately resistant to P. sanguineus. For the extracted heartwoods, the lowest mass loss against P. sanguineus was achieved by T. gabonensis heartwood which was the richest in G type units. The highest mass loss was obtained from the three other heartwoods displaying the highest content on S units. Heartwoods with high crystallinity index and long cellulose fibers were more resistant to Antrodia sp. compared to A. klaineana which displayed the shortest cellulose fibers (624 μm) and the lowest crystallinity index (59%).

Resistance of the S1 layer in kempas heartwood fibers to soft rot decay

Naturally durable heartwoods, where available, continue to be used as support structures in environments considered hazardous, particularly in ground contact. However, durability of heartwoods against wood decay microorganisms varies. Therefore, it is important to evaluate heartwood products for their in-service performance in order to maximise benefits derived from this valuable natural resource of limited supply. In the work presented, wood pieces from a kempas (Koompassia malaccensis) utility pole that had been placed in service in an acidic soil in Malaysia, and in time had softened at the ground-line position, were examined by light and transmission electron microscopy to evaluate the cause of deterioration.Light microscopy (LM) provided evidence of extensive attack on fibre cell walls by cavity-producing soft rot fungi. Transmission electron microscopy (TEM) revealed in greater detail the distribution and micromorphologies of cavities as well as their relationships to the fine structure of fibre cell walls, which consisted of a highly electron dense middle lamella, a moderately dense S1 layer and a multilamellar S2 layer with variable densities, reflecting differences in lignin concentration. The resistance of the moderately dense S1 layer to soft rot was a feature of particular interest and is the main focus of the work presented. The resistance appeared to be correlated with high lignification of the outermost region of the S2 wall, interfacing with the S1 layer, an unusual cell wall feature not previously described for normal wood.

Mold and Decay Resistance of Thermally Modified Douglas-Fir Heartwood

Abstract Most thermal modification studies have attempted to improve the durability of sapwood; however, it may be more fruitful to improve the durability of heartwood that already has some inherent durability. The effects of pretreatments with boron or glycerol coupled with thermal modification on resistance to mold growth and fungal degradation were examined for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) heartwood, which is classified as moderately durable. Pretreatment with boron had marked effects on resistance to both mold and decay fungi, but the results were consistent with the well-known effects of this fungicide. Pretreatment with glycerol appeared to reduce mold resistance and had no effect on degradation by decay fungi. Thermal modification enhanced mold resistance with increasing temperature but had only a slight effect on decay resistance. These results suggest that thermal modification does not enhance performance to levels that meet North American durability requirements for aboveground, exterior exposures.

Prediction of the Decay and Termite Resistance of Western Red Cedar Heartwood

Abstract Western red cedar (WRC; Thuja plicata) is highly valued for its natural durability. Rapid methods to assess heartwood durability are needed to identify breeding stock that will ultimately yield trees with durable wood when harvested. Chromatographic methods to detect heartwood extractives have been developed, but these still require significant time and laboratory resources and rely upon an understanding of the relationship between extractives and durability that is still incomplete. Visible/near-infrared (VIS/NIR) spectroscopy combined with multivariate statistical analysis has been used to rapidly predict a wide range of wood properties, including extractive content and decay resistance. The present work investigates the ability of VIS/NIR spectroscopy to predict extractive content, decay resistance, and termite resistance of WRC heartwood and explores the association between extractive content and durability. Partial least squares (PLS) models based on VIS/NIR spectra had moderate predictive ability for lignans, plicatic acid, beta-thujaplicinol, and total extractives. Other extractives were poorly predicted. Developed PLS models were not predictive for decay resistance but were moderately predictive of termite resistance. Decay and termite resistance were not strongly associated with any measured extractive. A moderately strong correlation was observed between termite resistance and red coloration (a*). Some of the models developed may be suitable for screening, but none are accurate enough for phenotyping.

Natural Durability and Apparent Specific Weights of Acrocarpus fraxinifolius Wight & Arn (Pink Cedar) Cultivated in the Province of Misiones, Argentina.

The objectives of this study were to explore the natural durability of heartwood and sapwood facing the action of the fungus Laetiporus sulphureus BAFC: 205, and also to determinetheapparent specific weightsof twelve years old Acrocarpus fraxinifolius Wight & Arn tree woods (Pink cedar), grown in Misiones, Argentina. The selected trees werefelledand sectionedinto logs, then sawed into strips from which the samples were obtained in order to carry out the durability testing following the modified European Norm No 113, and the apparent specific weight using theIRAM Argentine Norm No.9544. The results showed that heartwood is non-resistant, sapwood is perishable, and also according to the apparent specific weight it must be classified as half-heavy wood.We conclude that the A. fraxinifolius wood can be used mainly for interior constructions and for furniture.

Investigations on natural durability of important European wood species against wood decay fungi. Part 1: Laboratory tests

The durability of heartwood from European larch, Sessile oak and Scots pine was tested in laboratory against wood decay basidiomycetes and soft rot. The durability test was performed according to CEN/TS 15083-1:2005 with Coniophora puteana, Oligoporus (Poria) placenta and Trametes (Coriolus) versicolor. CEN/TS 15083-2:2005 was applied in order to test the timber with a bioactive soil substrate against soil rotting organisms. For Sessile oak, a very high durability against basidiomycetes (DC 1) was found in contrast to a low durability (DC 4) against soft rot fungi. Furthermore the results indicated that the durability of European larch and Scots pine is slightly deteriorated after leaching according to EN 84:1997. Beside this a minor influence of raw density on mass loss was detected for larch.

Effects of lateral wood zone on brown rot resistance of untreated and linseed oil-impregnated Scots pine wood

Various oils can be used to lower the equilibrium moisture content and increase the service life of Scots pine wood products. The aim of this study was to investigate effects of the lateral wood zone on the brown rot resistance of untreated and linseed oil-impregnated Scots pine wood in a laboratory test (EN 113). Significant differences were found in the mean mass losses of treated and untreated specimens taken from three lateral heartwood zones, but not between specimens taken from sapwood. The treatment had no significant effect on sapwood, although it seems to have some positive effect on the durability of heartwood, apparently due to interactive effects with the high extractives contents of heartwood.

Comparative termite resistance of 12 Malaysian timber species in laboratory tests

Abstract The effect of wood density and extractive compounds on heartwood durability against subterranean termites was studied. Twelve species of Malaysian hardwoods were tested against Coptotermes curvignathus and C. gestroi using a standard laboratory method. The results indicated that amount of extractive content is related to Malaysian hardwood termite durability.

Durabilidade natural da madeira de três espécies florestais em ensaios de campo.

Com o objetivo de avaliar a durabilidade natural da madeira, amostras de alburno e de cerne de Luehea divaricata (açoita-cavalo), Carya illinoinensis (nogueira-pecã) e Platanus x acerifolia (plátano), medindo 2,5 x 2,5 x 30,0 cm (radial x tangencial x longitudinal), foram submetidas a ensaios experimentais em um povoamento de Pinus e em campo aberto. Durante um ano, as amostras foram periodicamente pesadas e avaliadas pelo critério de notas, para determinar o percentual de perda de massa e índice de deterioração, respectivamente. Os resultados mostraram que, independente da espécie e do tipo de lenho, o ambiente dentro da floresta é mais favorável a deterioração da madeira do que fora dele. Apesar da elevada correlações entre a perda de massa e o índice de deterioração foram observadas variações na avaliação da durabilidade da madeira entre esses critérios. Para todas as espécies, a madeira proveniente do alburno foi a mais atacada. Para perda de massa não foi observada diferença entre as espécies avaliadas, entretanto, o índice de deterioração apontou o plátano como a mais atacada.

Natural durability and phenolic content in dried Scots pine heartwood

The durability of Scots pine heartwood has previously been shown to be affected by the industrial drying process of sawn lumber. The durability of heartwood from boards dried at temperatures between 20°C-110°C was studied by measuring the mass loss in a decay test with a brown rot fungus (Coniophora puteana), and the concentration of total phenolics was measured according to the Folin-Ciocalteu (FC) assay. The relation between mass loss and phenolics in dried heartwood showed a weaker negative correlation at lower levels of phenolics as compared to the strong relationship found in a study on heartwood from standing Scots pine trees. Mass loss in dried heartwood showed a weak negative correlation to density. Heating of extractives-rich green sawdust under moist conditions resulted in a reduction of phenolics with temperature up to 180 oC and with increasing time. The concentration of phenolics in heated, green sawdust was higher in extractives-rich pine heartwood than in heartwood with a normal extractives content.

Natural durability of heartwoods from European and tropical Africa trees exposed to marine conditions

Marine durability of heartwoods obtained from tropical African and European species against marine borer attacks in underwater exposure in Turkish coasts was investigated. Test hangers including wood species of 18 European and 15 African wood species were fastened to test area and exposed at a depth of 6 m along the coasts of seas (East and West Black Sea, Marmara Sea, Aegean, East and West coasts of mediterranean in Turkey seashore). Most European wood samples suffered severe attacks from boring organisms. On the other hand, some tropical African species (Lophira alata, Nauclea diderichii, Tieghemella heckelii, Chlorophora excelsa, Distemonanthus benthamianus, Pterocarpus soyauxii and Millettia laurentii) showed high natural marine durability in all seas, while the rest of them were only

Wounding response in xylem of Scots pine seedlings shows wide genetic variation and connection with the constitutive defence of heartwood

In this greenhouse experiment, 3-year-old Scots pine (Pinus sylvestris L.) seedlings were wounded by drilling holes through the stem. In the xylem next to the wound, the concentration of resin acids (RAC) increased, and the production of extractives typical for heartwood (stilbenes) and knotwood (stilbenes and lignans) of mature trees was induced. The induced stilbenes were pinosylvin (PS) and pinosylvin monomethyl ether (PSM), and the lignans nortrachelogenin (NTG) and matairesinol (MR). There was positive phenotypic correlation between concentrations of the different extractives. Except for the RAC, the extractive concentrations showed no correlation with the size of the seedlings. The treated seedlings belonged to half-sib families, which enabled the estimation of the genetic parameters for the response variables. The proportion of heritable variation (heritability, h(2)) in the concentration of PS, NTG and MR varied between 0.71 and 1.03, whereas for PSM and RAC the heritability was lower (0.35 and 0.31). Genetic correlation was significant between PS and PSM (r = 0.55, P = 0.018), and between NTG and MR (r = 0.50, P = 0.033). Heritabilities were also estimated on the basis of the regression of the offspring on their mothers h(2)(0P). These estimates were assessed for the concentration of PS, PSM and RAC in the wound response area of the seedlings and correspondingly in the heartwood of their mothers. The heritability was highest for the concentration of PS h(2)(0P). The findings of this study support the suggestion that the wounding of Scots pine seedlings may facilitate the development of an early testing method for breeding heartwood durability.

Protection by tropolones against H2O2-induced DNA damage and apoptosis in cultured Jurkat cells

Tropolones, the naturally occurring compounds responsible for the durability of heartwood of several cupressaceous trees, have been shown to possess both metal chelating and antioxidant properties. However, little is known about the ability of tropolone and its derivatives to protect cultured cells from oxidative stress-mediated damage. In this study, the effect of tropolones on hydrogen peroxide-induced DNA damage and apoptosis was investigated in cultured Jurkat cells. Tropolone, added to the cells 15 min before the addition of glucose oxidase, provided a dose dependent protection against hydrogen peroxide induced DNA damage. The IC50 value observed was about 15 μM for tropolone. Similar dose dependent protection was also observed with three other tropolone derivatives such as trimethylcolchicinic acid, purpurogallin and β-thujaplicin (the IC50 values were 34, 70 and 74 μM, respectively), but not with colchicine and tetramethyl purpurogallin ester. Hydrogen peroxide-induced apoptosis was also inhibited by tropolone. However, in the absence of exogenous H2O2 but in the presence of non-toxic concentrations of exogenous iron (100 μM Fe3+), tropolone dramatically increased the formation of single strand breaks at molar ratios of tropolone to iron lower than 3 to 1, while, when the ratio increased over 3, no toxicity was observed. In conclusion, the results presented in this study indicate that the protection offered by tropolone against hydrogen peroxide-induced DNA damage and apoptosis was due to formation of a redox-inactive iron complex, while its enhancement of iron-mediated DNA damage at ratios of [tropolone]/[Fe3+] lower than 3, was due to formation of a lipophilic iron complex which facilitates iron transport through cell membrane in a redox-active form.

Rapid prediction of natural durability of larch heartwood using Fourier transform near-infrared spectroscopy

The feasibility of Fourier transform near-infrared (FT-NIR) spectroscopy for rapidly determining the natural durability of the heartwood of larch trees (Larix decidua Mill. and Larix kaempferi (Lamb.) Carrière) was investigated. FT-NIR spectra were collected from solid wood with a fibre-optical probe. Basidiomycetes tests using Coniophora puteana and Poria placenta were carried out on larch heartwood (European standard EN 113), with pine sapwood (Pinus sylvestris L.) used as a reference. The relative resistance to decay (x value) was calculated, and durability classes were estimated according to European standard EN 350-1. Partial least squares regressions between the data sets of wood decay tests (x values) and the FT-NIR spectra were calculated. It was found that multiplicative scatter correction considerably improved the model predictability. High coefficients of correlation (r) and low root mean square errors of prediction (RMSEP) were obtained for cross validation based on wood decay tests with P. placenta (r = 0.92, RMSEP = 0.077, range 0.27-1.13) and C. puteana (r = 0.97, RMSEP = 0.078, range 0.07-1.58). Overall, NIR spectroscopy has proven to be an accurate and fast method for the nondestructive determination of natural durability, which might be highly relevant for intensive tree breeding programs and for efforts to optimize wood utilization.

Fungicidal activity of beta-thujaplicin analogues.

The fungicidal activity of analogues of beta-thujaplicin, a natural product responsible for the durability of heartwood of several cupressaceous trees, was investigated in vitro on the growth of different white and brown rot fungi involved in wood biodegradation, Coriolus versicolor, Phanerochaete chrysosporium, Poria placenta and Gloephyllum trabeum. The study shows that 2-hydroxycyclohepta-2,4,6-trienone (tropolone), easily prepared according to a literature procedure, possesses interesting fungicidal activity when compared to beta-thujaplicin, azaconazole, tebuconazole and copper oxine, which suggests this compound should be examined further as a potential biocide for wood preservation.

Heartwood decay resistance by vertical and radial position in Douglas-fir trees from a young stand

Heartwood durability of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) was studied as a function of vertical and radial position in boles of trees with a wide range of leaf area/sapwood area ratios. Six 34-year-old trees were harvested from each of three plots established 14 years before: very dense, thinned, and thinned and fertilized. Heartwood samples from three radial positions and five heights were incubated with the decay fungus Postia placenta (Fr.) M. Larsen et Lombard. There were no significant differences in wood mass loss (decay resistance) by vertical or radial position. One could expect that trees with high leaf area/sapwood area could have the carbon to produce heartwood that is more resistant to decay than trees with lower leaf area/sapwood area. However, we found no relationship between leaf area above node 20, sapwood area there, or their ratio, and the decay resistance of outer heartwood at that node. These results suggest that, for young Douglas-fir trees, heartwood durability does not vary with position in the bole or with environments that alter the tree's balance of sapwood and leaf area. We suggest that young stands may thus be robust with respect to the effect of silvicultural regimes on heartwood durability.

Flavonoids and Isoflavonoids with Antifungal Properties fromPlatymiscium yucatanumHeartwood

Platymiscium yucatanum is a tropical wood highly resistant to the fungi Lenzites trabea and Coriolus versicolor. In order to determine the reason for this property, heartwood extracts and isolated compounds were tested in vitro against these fungi. The methylene chloride extract completely inhibited (5 mg/ml) the mycellium growth of both fungi. Chromatographic separation of the extract afforded several flavonoids and isoflavonoids, among them the novel 4,2',5'-trihydroxy-chalcone, isoliquiritigenin (4,2',4'-trihydroxychalcone), (+)-liquiriti-genin, (+)-medicarpin, and homopterocarpin. The coumarin aesculetin dimethyl ether was also isolated. Antifungal activity of five of the isolated compounds were measured at 0.25 mg/ml. (+)-Medicarpin and the two chalcones inhibited the growth of both fungi. Aesculetin dimethyl ether and (+)-liquiritigenin were only active against C. versicolor. (+)-Medicarpin was the most active of the compounds tested and had greater activity than phenol against C. versicolor. The results suggest that the various compounds present all contributions in some degree to the heartwood durability, but not all compounds are equally effective.