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1.
This paper evaluated the density and biological resistance of pinewood samples modified with thermo-mechanical densification and thermal post-treatment. The samples were densified with 20 and 40% compression ratios at either 110 or 150 °C. The thermal post-treatment was then applied to the pine samples at 185 and 212 °C for 2 h. These samples were exposed to white-rot (Trametes versicolor) and brown-rot (Coniophora puteana) fungi for twelve weeks and the resulting mass loss was determined. In the densified samples, the effects of the compression ratio on T. versicolor-initiated mass loss and of the compression temperature on C. puteana-initiated mass loss were found to be significant. The mass loss was less in the samples compressed at 150 °C with the 40% ratio, while the highest mass loss was observed in the undensified samples. In the thermally post-treated samples, the resistance to both decay fungi was significantly increased with the increase of the treatment temperature. The mass loss in the thermally post-treated samples at 212 °C after T. versicolor and C. puteana fungi testing was reduced by 73 and 67%, respectively. However, the effect of the densification processes on decay resistance in the thermally post-treated samples was insignificant. 相似文献
2.
《Wood material science & engineering》2013,8(4):242-244
Abstract This study assessed the decay resistance of Pinus leucodermis wood to the brown-rot fungus Coniophora puteana. Based upon the median weight losses of 30.65% for heartwood and of 34.68% for sapwood obtained in the biological tests, both the heartwood and sapwood material examined was classified as not durable (durability class 5) according to the CEN/TS 15083-1 classification. Total extractives were low, 3.93% in heartwood and 1.00% in sapwood, while lignin content was 22.60% and 25.41% in heartwood and sapwood, respectively. It is highly recommended to use protective treatments before using P. leucodermis wood in outdoor conditions. 相似文献
3.
Amine Moubarik Bertrand Charrier Fatima Charrier Antonio Pizzi Ahmed Allal 《Annals of Forest Science》2009,66(1):109-109
4.
《Southern Forests》2013,75(3):223-234
The aims and objectives of this study were to investigate the potential to predict laminated veneer lumber (LVL) stiffness from wood properties measured on trees and logs, and determine variation in log, wood and veneer properties as a function of tree height and age. Log selections were made from trees in three stands that were planned for harvesting at 14, 20 and 21 years of age. Rotary peeled veneer recovery from the logs was on average 65%. After drying, Metriguard testing showed over 50% of the veneer had an estimated dynamic modulus of elasticity (MOEdyn) above 12 GPa, with 20% above 14 GPa, and that veneer from the second log by tree height had higher MOEdyn values. In visual assessment to the AS/NZS 2269.0:2012 Standard, no veneer could be utilised in a panels face or subface positions and the older-age stand provided almost four times the volume of usable veneer. Standing-tree acoustic wave velocity (AWV) explained a moderate amount of variance in log MOEdyn and Pearson correlation coefficients between the (Metriguard) veneer MOEdyn, log AWV, log MOEdyn and disc basic density were significant, positive and strong, with log AWV explaining most of the observed variance in log stiffness. A moderately strong and positive linear regression existed between log AWV and veneer MOEdyn, supporting the use of log AWV tools for the ranking of stiffness in fibre-grown plantation E. nitens logs. Mechanical strength testing of LVL studs extracted from panels manufactured from the trial’s veneer indicated they equalled, and for some tested parameters exceeded, the characteristic design strength values previously published by commercial LVL manufacturers for equivalent size pine products. 相似文献
5.
Heat treatment of wood at relatively high temperatures (in the range of 150–280°C) is an effective method to improve biological
durability of wood. This study was performed to investigate the effect of heat treatment process optimisation on the resistance
against fungal attack, including basidiomycetes, molds and blue stain fungi. An industrially used two-stage heat treatment
method under relatively mild conditions (<200°C) was used to treat the boards. Heat treatment of radiata pine sapwood revealed
a clear improvement of the resistance against the brown rot fungi Coniophora puteana and Poria placenta. Increasing process temperature and/or effective process time during the first process stage, the hydro thermolysis, appeared
to affect the resistance against C. puteana attack, but the effect on the resistance against P. placenta was rather limited. Heat treated radiata pine showed a limited resistance against the white rot fungus Coriolus versicolor and process variations during the hydro thermolysis stage appeared not to affect this resistance. A clear difference between
the resistance of heat treated Scots pine sapwood and heartwood against fungal attack is observed. Scots pine heartwood showed
a higher resistance against C. puteana and P. placenta but also against the white rot fungus C. versicolor. Similar results were obtained when heat treated birch was exposed to brown and white rot fungi. Heat treatment showed an
improved resistance against C. puteana attack, especially at higher temperatures during the hydro thermolysis stage. A clear improvement of the durability was also
observed after exposure to the white rot fungus C. versicolor and especially Stereum hirsutum. Increasing the process temperature or process time during the hydro thermolysis stage appeared to have a limited effect
on the resistance against C. versicolor attack. Heat treated radiata pine and Norway spruce were still susceptible to mold growth on the wood surface, probably due
to the formation of hemicelluloses degradation products (e.g. sugars) during heat treatment. Remarkable is the absence of
blue stain fungi on heat treated wood specimen, also because the abandant blue stain fungi were observed on untreated specimen.
Molecular reasons for the resistance of heat treated wood against fungal attack are discussed in detail contributing to a
better understanding of heat treatment methods. 相似文献
6.
Potential of indigenous multistrata agroforests for maintaining native floristic diversity in the south-eastern Rift Valley escarpment, Ethiopia 总被引：3，自引：2，他引：1
Most studies undertaken in the field of agroforestry have focussed on system design, soil fertility management, and system interactions. Less emphasis has been placed on biodiversity aspects. The aim of this study is to investigate the potential of indigenous, multistrata agroforests for maintaining native woody species diversity in the south-eastern Rift Valley escarpment, Ethiopia. A total of 60 farms, representing three agroforest types (enset-AF, enset-coffee-AF and fruit-coffee-AF), were randomly selected along altitudinal gradients. Enset (Ensete ventricosum) is a perennial, herbaceous monocarpic banana-like plant which serves as a food plant in Ethiopia. The three agroforests are results of the domestication of natural forests and intensification of the landuse systems centuries ago. Sample-based assessment protocols were employed to place sample quadrats and to measure all individuals in the quadrats. A total of 58 woody species, belonging to 49 genera and 30 families, was recorded. Of all woody species identified, 86% were native. The highest proportion of native woody species was recorded in enset-AF (92%), followed by enset-coffee-AF (89%) and fruit-coffee-AF (82%). Among native tree species, Millettia ferruginea and Cordia africana were the most widespread. In all, 22 native woody species were recorded as of interest for conservation, acccording to IUCN Red lists and local criteria. Among them, Pygeum africanum and Rhus glutinosa were categorised as vulnerable in the wild, and in need of conservation priority. The introduction of non-native fruit trees in agroforests can be a threat to maintenance of native woody species. Management strategies favoring enset and coffee will also put other native tree species at risk. A smaller number of native woody species was recorded in fruit-coffee-AF, but a higher mean basal area and stem number. The mean basal area and stem number ranged from 5.4?±?0.5 to 11.7?±?1.0?m2?ha?1 and 625?±?84 to 1,505?±?142 stems?ha?1, respectively. Altitude explained 68 and 71% of the variation in species richness and abundance, respectively. Finally, it is concluded that recognition of the indigenous agroforestry system as an option for maintaining native woody species should be given more attention, to counteract the local threat of these species from the wild. 相似文献
7.
The aim of this study is to characterise the properties of juvenile and mature heartwood of black locust (Robinia pseudoacacia L.). Content, composition and the subcellular distribution of heartwood extractives were studied in 14 old-growth trees from
forest sites in Germany and Hungary as well as in 16 younger trees of four clone types. Heartwood extractives (methanol and
acetone extraction) were analysed by HPLC-chromatography. UV microspectrophotometry was used to topochemically localise the
extractives in the cell walls. The natural durability of the juvenile and mature heartwood was analysed according to the European
standard EN 350-1. Growth as well as chemical analyses showed that, based on extractives content, the formation of juvenile
wood in black locust is restricted to the first 10–20 years of cambial growth. In mature heartwood, high contents of phenolic
compounds and flavonoids were present, localised in high concentrations in the cell walls and cell lumen of axial parenchyma
and vessels. In juvenile wood, the content of these extractives is significantly lower. Juvenile wood had a correspondingly
lower resistance to decay by Coniophora puteana (brown rot fungus) and Coriolus versicolor (white rot fungus) than mature heartwood. 相似文献
8.
Joseph Dahlen P. David Jones R. Daniel Seale Rubin Shmulsky 《Wood Science and Technology》2013,47(6):1167-1176
Visually graded Douglas-fir (DF) has wide variability within grade. Variability for 2 × 4 lumber has likely increased because harvest has shifted from federal forests to private plantation forests that contain high percentages of juvenile wood. To investigate resource variability, six No. 2, 2 × 4 DF packages were acquired from six mills. From each package, 124 samples were destructively tested in bending. Mean modulus of elasticity (MOE15) ranged from 9.8 to 13.4 GPa, and three mills did not meet the grade requirements (11.0 GPa). Bending strength (F b) ranged from 5.5 to 11.3 MPa, and three mills did not meet the grade requirements (9.3 MPa). ANOVA of MOE15 % and F b showed significant differences at the 0.05 significance level. MOE15 explained from 50 to 78 % of the variability in strength. These data suggest that variation between mills is high and destructive testing is critical for more accurate characterization of lumber properties. 相似文献
9.
There are indications that the drying process may have negative effects on the natural durability of wood. The impact of various
drying processes on the durability of Scots pine lumber has been evaluated with mass loss in a decay test with brown rot fungus,
Coniophora puteana, as measure of the decay resistance of sapwood and inner and outer heartwood. Drying with or without steam conditioning was
performed in six different series: air drying, kiln drying at temperature ranges commonly used in Swedish sawmills at 70°C
and 90°C with two different regulation principles, and one high-temperature drying at 110°C. Durability varied considerably
both between and within boards. Sapwood showed considerable less durability than heartwood. No difference in durability was
found between inner heartwood and outer heartwood. Air-dried heartwood showed the highest durability compared to other drying
series. The lowest durability in sapwood and heartwood was found for series dried at the 90°C temperature level with high
material temperature early in drying. The interpretation is that the duration of high material temperature at high moisture
content (MC) is the critical combination for decay resistance in heartwood. Steam conditioning after drying decreased durability
in sapwood. 相似文献
10.
《Wood material science & engineering》2013,8(2):101-106
Abstract The effect of heat treatment on decay resistance of white birch was evaluated for different incubation periods ranging from 2 to 12 weeks using three species of brown rot and one species of white rot fungus. The results of weight loss tests showed that the white rot fungus, Trametes versicolor, effectively degraded the untreated wood (73.5%). While the degradation of untreated wood by brown rot fungi species, Gloephyllum trabeum (11.6%) and Conifora puteana (6.2%), was considerably less compared to T. versicolor, the third brown rot fungi studied, Poria placenta, caused an appreciable degradation of the same species (52.4%). The results clearly showed that the heat treatment reduced the effect of fungi attack on white birch. Increasing the heat treatment temperature from 195 to 215°C resulted in reduction of weight loss, consequently, reduction in fungal attack. As an example, the weight loss reductions due to T. versicolor, P. placenta, G. trabeum and C. puteana attack was 62.2%, 71.3%, 89.6% and 100%, respectively, compared to the weight loss of untreated wood when it is heat treated at 215°C. Thus, these results confirmed that the heat treatment increased the biological resistance of white birch. 相似文献
11.
Yannick Curnel Dominique Jacques Notburga Gierlinger Luc E. Pâques 《Annals of Forest Science》2008,65(8):810-810
12.
S. Nami Kartal Christian Brischke Andreas O. Rapp Yuji Imamura 《Wood Science and Technology》2006,40(1):63-71
Evaluation of wood preservatives in soil-contact tests is becoming an important issue since detoxification of wood-protecting
compounds by fungi and bacteria found in soil may decrease the resistance of treated wood. In this study, the decay resistance
of wood treated with didecyl dimethyl ammonium tetrafluoroborate (DBF), a recently developed quaternary ammonia compound,
was evaluated in both soil bed and laboratory decay resistance tests. Small specimens (5×10×100 mm3) of DBF-treated and untreated sugi sapwood were subjected to decay in laboratory soil bed tests (DIN ENV 807 (2001)) followed
by Basidiomycetes tests (DIN EN 113 (1996)). Exposure in field soil and compost soil substrates was used to observe the effects
of wood degrading and other soil-inhabiting micro-organisms on the decay resistance of the specimens. Soil bed tests showed
that DBF-treated wood specimens at 7.7 kg/m3 retention level (1% DBF solution concentration) showed better performance compared to 0.01 and 0.1% DBF treatments. The 7.7 kg/m3 retention level was also effective to protect the wood specimens against Coniophora puteana and Coriolus versicolor in Basidiomycetes tests. It is concluded that detoxification of wood preservatives in soil contact is an important factor
to determine protective properties of treated wood in ground contact applications. Further experiments with larger specimens
are needed to observe the performance of DBF-treated wood at higher retention levels in field above ground and ground contact
tests.
Dedicated to Prof. Dr. H.C. Mult. Walter Liese on the occasion of his 80th birthday. 相似文献
13.
《Forest Ecology and Management》2004,199(1):115-123
Studies on basic density of woody species in Amazonian savannas are needed to convert data on woody volume to biomass. These ecosystems, which have large carbon stocks, emit greenhouse gases annually due to frequent burnings. Basic density (g cm−3: oven-dry weight/wet volume), measured from complete sample disks (bark, sapwood and heartwood), was calculated for the most abundant woody species in three types of open savannas (Sg: grassy-woody savanna; Sp: savanna parkland; Tp: steppe-like parkland) in Roraima, a state in the northern part of Brazil’s Amazon region. The species selected represent 90–95% of the woody biomass estimated in these ecosystem types. Seven additional species were lumped in an “others” group. In total, we sampled 107 trees: 40 in Sg, 37 in Sp and 30 in Tp. Bowdichia virgilioides (0.516 ± 0.021 (S.E.) g cm−3) was the species with the highest basic density, followed by the “others” group (0.485 ± 0.057 g cm−3), Curatella americana (0.413 ± 0.028 g cm−3), Byrsonima crassifolia + B. coccolobifolia (0.394 ± 0.019 g cm−3), Himatanthus articulatus (0.375 ± 0.020 g cm−3) and B. verbascifolia (0.332 ± 0.020 g cm−3). Basic density of the species with the greatest woody biomass in Roraima’s open savannas (C. americana and B. crassifolia + B. coccolobifolia) did not differ significantly at the 5% level (ANOVA) among the three ecosystem types studied. Wood basic density in these savannas (weighted mean = 0.404 ± 0.025 g cm−3) is lower than that in Amazonian forests (weighted mean = 0.680 g cm−3). These results reduce uncertainty in calculations of carbon stocks and of greenhouse gas emissions from clearing and burning tropical savanna. 相似文献
14.
Natural durability of two plantation woods, Chinese fir and I-214 poplar, was investigated thoroughly by three testing methods,
namely an accelerated laboratory decay test, a fungus cellar test and a field test. After the decay test using Postia placenta and Trametes versicolor, Chinese fir and the I-214 poplar showed 34% and 69% of mass loss, respectively, indicating they should be classified as
slightly durable and non-durable wood. This conclusion was confirmed by the fungus cellar test and the field test. Like the
performance in the decay test, I-214 poplar showed no resistance to termites either in the laboratory or in the field, whereas
Chinese fir would be classified as moderately resistant.
[Supported by Sino-Japanese Technical Cooperation Project Titled “Studies on Chinese Plantation Wood” (JICA PROJECT/033-1418-E-O)] 相似文献
15.
Te-Hsin Yang Song-Yung Wang Cheng-Jung Lin Ming-Jer Tsai Far-Ching Lin 《Journal of Wood Science》2007,53(1):31-39
The purpose of this study was to measure the strain of glulam laminae by affixing a strain gauge at the central axis of the
lateral face in order to determine the effect of the configuration of the glulam. Japanese cedar and southern pine were used
in the study. The strain and stress of the laminae during the bending test were recorded, and the modulus of elasticity (MOE) was calculated. The influence of the MOE of the adhesive layers was also considered. Results showed that the MOE of the laminated elements increased as its specific gravity increased, although the specific gravity was not the only factor
evaluated. The MOE of glulam (E
bsg) measured by the strain gauge method was very close to the observed MOE of glulam (E
b) and a significant linear relationship was identified. The MOE (e) of laminae measured by the strain gauge method was very close to that determined (E) under the “free condition” before bonding. The difference between the modified MOE (E
bsa) and E
bsg was not significant. The MOE of glulams made of heterogeneously graded lumbers were about 23% and 31% larger than the average MOE of their laminae for Japanese cedar and southern pine, respectively. The actual neutral axis was just below the longitudinal
center line. It shifted slightly within the proportional limit range and moved downward when the load increased. 相似文献
16.
17.
Joseph Dahlen P. David Jones R. Daniel Seale Rubin Shmulsky 《Wood Science and Technology》2013,47(6):1153-1165
Visually graded southern pine (SP) has wide variability within grade. For 2 × 4 lumber, this variability has increased because it is harvested from both natural forests and plantation forests where trees contain high percentages of juvenile wood. To investigate resource variability, six kiln-dried No. 2 2 × 4 SP packages were acquired from six mills. From each package, 124 samples were destructively tested in bending. Mean modulus of elasticity (MOE15) ranged from 9.2 to 13.1 GPa, and three mills did not meet the design values (11.0 GPa). Bending strength (F b) ranged from 7.6 to 11.9 MPa, and four mills did not meet the design values (10.3 MPa). Analysis of variance of MOE15 and F b showed significant differences between mills. MOE15 explained from 33 to 51 % of the variability in F b. These data suggest that variation between mills is high and destructive testing is critical for more accurate characterization of lumber properties. 相似文献
18.
Species-specific oligonucleotide primers for detecting wood rot fungi, Gloeophyllum trabeum, Trametes versicolor, Coniophora puteana, and Serpula lacrymans, and the primer detecting a group of related fungi to G. sepiarium were developed. These primer sequences were picked up from the internal transcribed spacer region between small-subunit rDNA
and large-subunit rDNA. The species selectivities of the developed primers were checked. Real-time polymerase chain reaction
(PCR) was carried out using these highly specific primers to quantitatively detect at least of 0.01 ng genome DNA of the target
species. This quantitative PCR was also used to differentiate the target species DNA from mixed species DNA. A PCR-based technique
using the species-specific primers would be applicable to multiple-sample assay in diagnosis of wood decay and to investigation
of environmental fungal populations.
Part of this article was presented at the International Symposium on Wood Science and Technology (IAWPC 2005), Yokohama, November
2005 相似文献
19.
This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.An erratum to this article can be found at 相似文献
20.
Acoustic emissions of pine wood samples (Pinus sylvestris L.) previously infected with the soft-rot fungi (Chaetomium globosum Kunze) and brown-rot fungi (Coniophora puteana (Schum. ex Fr.) Karst.) were measured in the perpendicular to grain compression test, in the radial direction. It was found
that even a minimum mass loss (below 1%) caused by enzymatic deterioration of the wood substance resulted in an increase in
acoustic emission level in the compression test measured perpendicular to grain in the radial direction. A particularly sensitive
indicator of wood enzymatic destruction were cumulative counts of acoustic emission related to the value of the applied compression
load.
Received 4 March 1997 相似文献