Brown-rot Decay Research Articles

From deadwood to forest soils: quantifying a key carbon flux in boreal ecosystems

Deadwood represents a dynamic carbon pool in forest ecosystems where microbial decomposition causes fluxes of CO2 to the atmosphere through respiration and organic carbon to the soil through leakage and fragmentation. This study characterises different stages of deadwood of Norway spruce (Picea abies). 35 Norway spruce trees were sampled and categorized on a 0–5 decay scale. For the 14 trees in classes 0–3, two stem discs were collected from two heights. For the 21 trees in classes 4 and 5, a single sample per tree was taken, because decay was relatively uniform throughout the stem. The relative amount of hemicellulose and cellulose declined moderately from decay class 1 to 3 and substantially from decay class 3 to class 4 but small amounts were still present in decay class 5. The relative lignin proportion increased substantially from decay class 3 to 4 and dominated in decay class 5. Relative carbon content increased from 50 to 56% during the decomposition process due to the increasing accumulation of lignin residuals being a typical signature of brown rot decay. A laboratory experiment including three species of brown rot fungi verified decomposition close to 70% of Norway spruce biomass and resulted in 55% carbon content. This was similar to the carbon content in decay class 4 and 5. A novel approach is presented to quantify the carbon flux from deadwood to the soil. First, we calculated the residual proportion of carbon in decayed wood compared to the initial carbon content of live trees. Subsequently, we extended the calculation to determine the amount of remaining carbon from non-decayed wood that was transferred to the soil during each decay class. The approach showed that Norway spruce wood decomposition under field conditions transfers at least 39–47% of the initial wood carbon to the soil carbon pool, depending on soil type. This strengthens the previously under-communicated fact that the carbon flux from deadwood to soil is higher from brown rot decomposition in boreal forests than the corresponding carbon flux in temperate and tropical forests where deadwood is more influenced by white rot fungi.

Synthesis and preservation performance of lanthanum-tannin complex from Cercis glabra Pampan

This article explores the feasibility of rare earth element-tannin complexes as a wood preservative. The tannins (T) from Cercis glabra Pampan. are extracted, sulfonated (ST), and coordinated with lanthanum (La) elements to fabricate the complexes (La-T, and La-ST). Results show that two stable complexes, La-T and La-ST, are successfully formed by coordinating the La-ions with the phenolic hydroxyl groups in T and ST. Sulfonated tannins have a better adsorption capacity for lanthanum ions. The mass percentage of La in La-ST (36.50%) is higher than that in La-T (24.85%). The results of the white-rot decay test reveal that wood treated with La-T (1.98%) and La-ST (2.58%) preservatives has significantly lower weight loss rates compared to the untreated (28.94%). However, the brown rot decay test demonstrates that wood treated with La-T (62.68%) and La-ST (50.81%) only has slightly lower weight loss rates compared to the untreated (71.84%). Finally, the leaching of La-T and La-ST treated poplar wood was significantly lower than La self-treated ones. This novel approach can produce stable rare earth-wood preservatives and improve the wood's bio-durability and anti-leaching properties, thus remarkably enhancing the outdoor performance of modified wood products.

Dimensionally stable and durable wood by lignin impregnation

Cracking, warping, and decaying stemming from wood's poor dimensional stability and durability are the most annoying issues of natural wood. There is an urgent need to address these issues, of which, sustainable and green chemical treatments are favorably welcomed. Herein, we developed a facile method through the incorporation of environmentally friendly biopolymer lignin into wood cells for wood dimensional stability and durability enhancement. Enzymatic hydrolysis lignin (EHL) was dissolved into various solvents followed by impregnation and drying to incorporate lignin into wood cells. Impregnation treatment was developed to incorporate into wood to improve its dimensional stability, durability, and micromechanics. The anti-swelling efficiency reached up to 99.4 %, the moisture absorption decreased down to 0.55 %, the mass loss after brown rot decay decreased to 7.22 %, and the cell wall elasticity as well as hardness increased 8.7 % and 10.3 %, respectively. Analyses acquired from scanning electron microscopy, fluorescent microscopy, and Raman imaging revealed that the EHL was successfully colonized in cell lumen as well as in cell walls, thus improved wood dimensional stability and durability. Moreover, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed EHL interaction with the cell wall components, thus the wood mechanical property was not impaired significantly, whereas nanoindentation data indicated even slight mechanical enhancement on the cell walls. This facile approach can improve the wood properties in multiple aspects and remarkably enhance the outdoor performance of modified wood products. In addition, using lignin as a natural modifying agent to improve wood performance will have a great positive impact on the environment.

Characterizing properties of fungal-decayed cross laminated timber (CLT) connection assemblies

The effects of brown rot decay fungi on mechanical properties of CLT connection assemblies were investigated. CLT connections evaluated were assembled with code approved angle bracket connectors and modelled as floor-to-wall systems in mass timber buildings. Physical changes, mass loss and quasi-static cyclic tests were used to assess the performance of connection assemblies up to 40 weeks after fungal inoculation. Peak load, stiffness, energy dissipation and ductility of connections were characterized based on force–displacement data generated from the destructive test of connections. Assemblies experienced up to 57 % loss in load carrying capacity and 90 % loss in energy dissipating capacity of the connections after 40 weeks of fungal exposure. Connection stiffness was only slightly impacted over this period but wetting and redrying caused significant degradation of connection ductility.

Degradation by brown rot fungi increases the hygroscopicity of heat-treated wood

Heat treatment increases the decay resistance of wood by decreasing its hygroscopicity, but the wood material remains degradable by fungi. This study investigated the degradation of heat-treated wood by brown rot fungi, with the aim of identifying fungal-induced hygroscopicity changes that facilitate degradation. Scots pine sapwood samples were modified under superheated steam at 200 and 230 °C and then exposed to Coniophora puteana and Rhodonia placenta in a stacked-sample decay test to produce samples in different stages of decay. Sorption isotherms were measured starting in desorption from the undried, decaying state to investigate their hygroscopic properties. Although there were substantial differences in degradative ability between the two fungi, the results revealed that decay by both species increased the hygroscopicity of wood in the decaying state, particularly at high relative humidity. The effect was stronger in the heat-treated samples, which showed a steep increase in moisture content at low decay mass losses. The reference samples showed decreased hygroscopicity in absorption from the dry state, while the heat-treated samples still showed an increase at low mass losses. Near infrared spectroscopy showed that the early stages of decay were characterised by the degradation of hemicellulose and chemical changes to cellulose and lignin, which may explain the increase in hygroscopicity. The results provide a new perspective on brown rot decay and offer insight into the degradation of heat-treated wood.

Simultaneous Thermal Analysis for characterization of fungal depolymerisation of Norway spruce

After fungal decay experiments chemical characterisation of the wood is often a routine and several methodological approaches are available. In this study, we tested if simultaneous thermal analysis (STA) is a valid alternative to traditional wet chemical methods since STA allows significantly smaller sample size and faster analysis. Three model fungi including the brown rot fungi Rhodonia placenta and Gloeophyllum trabeum and the white rot fungus Trametes versicolor were employed in the study using Norway spruce as substrate. The experiment was harvested after 10, 20 and 52 weeks. At each harvest interval, aliquots of the material were characterized by STA and wet chemical methods. The results validated that STA can be effectively used to estimate cell wall composition of brown rot depolymerised wood. However, STA slightly overestimated cellulose at brown rot decay above 50%. The method was not verified for simultaneous white rot because STA only estimated hemicellulose correctly compared to the wet chemical method. Hence, STA is considered suitable for brown rot fungi below 50% mass loss but not for simultaneous white rot because STA did not estimate cellulose and lignin correctly.

First Report of Brown Rot Caused by Monilinia polystroma on Sweet Cherry and Almond in Italy.

Brown rot decay is an important disease of pome and stone fruits. In Italy, the main pathogens on stone fruits are Monilinia laxa, M. fructigena, and M. fructicola (Spitaler et al. 2022a). In addition, Monilinia polystroma (G. Leeuwen) L. M. Kohn (van Leeuwen et al. 2002), was recently found in Italy on peach (Martini et al. 2014), pear (Martini et al. 2015), plum (Abate et al. 2018), apple (Rosati et al. 2021), and quince (Spitaler et al. 2022b). In South Tyrol province, sweet cherry (Prunus avium L.) and almond (Prunus dulcis Mill. D. A. Webb), plants of the Rosaceae family and belonging to stone fruits, were observed to be frequently affected by brown rot. Affected cherries as well as almonds showed brown lesions, covered by yellowish or buff-colored stroma in concentric rings. Symptomatic cherries became shriveled, while symptomatic almonds remained firm. To determine the pathogen, single spore isolates were obtained from five symptomatic fruits, each from a cherry orchard of the cultivar Kordia in July 2021 and almond trees of the variety Dulcis in August 2021. Both sample sites were situated in Vadena/Pfatten. Infestation in the cherry orchard, covered by a rain-protection foil, was determined to be about 1 %. In almond, over 50 % of the fruits of various ripening stages showed brown rot symptoms. On potato dextrose agar (PDA) at 22 °C and a photoperiod of 16 h, isolates from both fruits matched the morphological characteristics of M. polystroma (Vasić et al. 2016) within 14 days. DNA was extracted from mycelium and the rRNA encoding gene region using ITS4 and ITS6 primers as well as a genomic sequence of unknown function using the primers UniMon_Forw and UniMon_Rev (Petróczy et al. 2012), were amplified and sequenced. MegaBLAST analysis revealed 100 % identity with M. polystroma sequences of the NCBI GenBank (rRNA encoding region: NR_154198; genomic region: JN128836). Sequences were deposited in GenBank under the accession numbers OP642545/OP654171 (cherry) and OP642546/OP654172 (almond). Pathogenicity was confirmed with mature cherries cultivar Duroncino or almost mature almond fruit of the variety Dulcis, respectively: 16 samples each for both fruits were surface-sterilized by dipping in 75 % ethanol for 10 s and subsequent rinsing with sterile water for 10 s. Mycelial plugs (1 mm) were dislodged from a 7-day old colony and inserted in a 1 mm hole into the fruits. Incubation was performed in plastic boxes under the conditions described above. PDA-inoculated fruit were used as controls. All cherries and all almonds were completely covered by brown rot lesions 7 days and 15 days post inoculation, respectively. Control fruits remained symptomless. Conidia were produced in branched chains on mycelium-inoculated fruit. Conidia were one-celled, limoniform, hyaline, measuring 13.1 to 22.2 × 9.7 to 14.8 µm (cherry) and 14.1 to 20.8 × 10.7 to 15.3 µm (almond). Additionally, 16 fruits each were inoculated with 20 µL conidial suspension (5 x 10^3 spores/mL) from mycelium-inoculated fruits. All cherries as well as all almonds were completely covered by brown rot lesions 7 days and 15 days post inoculation. Control fruits remained symptomless. To confirm identity, the fungus was isolated from five spore-inoculated fruits each for cherry and almond. The isolates showed identical morphological features and sequence identity as the original isolates. To our knowledge, this is also the first report of M. polystroma on almond, while the pathogen has already been reported on sweet cherry in Poland (Poniatowska et al. 2016). These additional host plants identified in this study suggest a broad impact of M. polystroma on Italian stone fruit production. Due to the economically important cultivation of stone fruit, further knowledge about the pathogens' host range will help to assign brown rot symptoms to M. polystroma and to improve targeted control strategies.

Fine-scale cation dynamics and control by Rhodonia placenta and Pleurotus ostreatus during wood decay

Fungi are the primary decomposers of wood across the globe. They redistribute the vast pool of wood carbon to other parts of the carbon cycle using mechanisms that also have intriguing potential in bioconversion and biotechnology applications. To make a living in the relatively sparse microenvironment of wood, these filamentous fungi must import many of their needs, including cations. Understanding the timing of cation import can help us validate the functions of cations in wood decay and create a clearer understanding of these complex wood degradation mechanisms. In this study, we resolved cation timing dynamics across space for two fungi (brown rot fungus Rhodonia placenta and white rot fungus Pleurotus ostreatus) using a wood wafer system. We found some expected patterns of the cation dynamics for both fungi, and a clear role for iron at the early stages of brown rot decay. On the other hand, the lack of an increase in manganese during initial white rot decay was surprising. Unexpectedly, we also saw a spike in copper during early brown rot decay that demands more investigation as a potential player in the brown rot mechanism.

Subcellular level impact of extractives on brown rot decay of Norway spruce elucidated by confocal Raman microscopy and multivariate data analysis

Subcellular level impact of extractives on brown rot decay of Norway spruce elucidated by confocal Raman microscopy and multivariate data analysis

Pectin decomposition at the early stage of brown-rot decay by Fomitopsis palustris.

The sapwood of Japanese cedar (Cryptomeria japonica D. Don) was decayed by the brown-rot fungus Fomitopsis palustris under bright and dark conditions. Scanning electron microscopy revealed the presence of mycelia inside the wood even after 1 week from the start of fungal exposure. Moreover, holes were observed in the torus after fungal exposure. Ruthenium red staining revealed that the pectin in pits was largely absent for 3 weeks. These events occurred before the mass loss of wood samples was confirmed at the early stage. Moreover, FpPG28A was more highly expressed at the hyphal front on a pectin-containing medium under dark conditions compared with bright conditions. This up-regulation under dark conditions indicated that the pectin decomposition ability was promoted inside the wood where light could not reach. In conclusion, we suggest that the brown-rot fungus completed its hyphal expansion within the wood via pectin decomposition in pits before holocellulose decomposition.

Molecular phylogeny and taxonomy of the remarkable genus Leptoporus (Polyporales, Basidiomycota) with description of a new species from Southwest China.

Leptoporus is a rare and remarkable genus, mainly occurring in coniferous forests in the Northern Hemisphere. Recent phylogenetic studies showed that Leptoporus belongs to Irpicaceae in the phlebioid clade. It is worth noting that most species in the phlebioid clade can cause white-rot decay, except for the Leptoporus species, which can cause a brown-rot decay. In this study, we performed phylogenetic and taxonomic studies of Leptoporus and related genera. Molecular phylogenetic analyses were conducted based on sequences from multiple loci including the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA gene (nLSU), the largest subunit of RNA polymerase II gene (RPB1), the second largest subunit of RNA polymerase II gene (RPB2), and the translation elongation factor 1-α gene (TEF1). Combined with morphological characteristics, a new species, Leptoporus submollis sp. nov., is discovered and illustrated from Southwest China.

Evaluation of in situ preservation method applied at a terrestrial archaeological shipwreck site by use of sacrificial wood samples installed for 25 years

In 1995 remains of a 13th century shipwreck, “the Kronholmen cog”, was discovered in sandy soil at a golf green on the island of Gotland, Sweden. Prior to backfilling and in situ preservation, four sacrificial wood samples (SWS) of sound pine sapwood were installed for long-term monitoring of wood decaying processes. In year 2020, the site was re-opened to evaluate the protective nature of the site. All SWS and six archaeological samples were taken for a comparative analysis. Observations by light- and scanning electron microscopy showed severe microbial decomposition by fungi and bacteria. Based on occurrence of decay forms in the wood fibres, soft rot (SR) was identified as the main degrader of both SWS and in the first 2 cm of the heavily eroded archaeological material, accompanied by bacteria (type tunnelling bacteria (TB)). Moderate decay by bacteria (type erosion bacteria, EB) in archaeological samples indicated longer period during the last 700 years under waterlogged and anaerobic condition – e.g., protective. Only initial decay of erosion bacteria (EB) was observed in SWS, strongly indicating a non-protective environment during the last 25 years. Severe brown rot decay was established in SWS and archaeological wood located in the front of the wreck where burial conditions were most critical (0.5 m above groundwater level, and 0.4 below soil/air interface). Here, a total of 0.50 cm surface layer of SWS was lost, yielding an initial decay rate of 20% in 25 years. In general, surfaces were heavily attacked especially for archaeological samples, and plant roots penetrated the soft and degraded surface layer. We conclude that the site since backfilling in 1995 has been semi-oxygenated and has promoted more severe fungal decomposition of cultural heritage. Thus, the site is not able to protect and preserve the precious archaeological remains for future generations and actions must be taken. SWS are concluded to be an important technique for long term monitoring of archaeological sites preserved in situ.

Chemical Characterization and Visualization of Progressive Brown Rot Decay of Wood by Near Infrared Imaging and Multivariate Analysis.

Brown rot fungi cause a type of wood decay characterized by carbohydrate degradation and lignin modification. The chemical and physical changes caused by brown rot are usually studied using bulk analytical methods, but these methods fail to consider local variations within the wood material. In this study we applied hyperspectral near infrared imaging to Scots pine sapwood samples exposed to the brown rot fungi Coniophora puteana and Rhodonia placenta to obtain position-resolved chemical information on the fungal degradative process. A stacked-sample decay test was used to create a succession of decay stages within the samples. The results showed that the key chemical changes associated with decay were the degradation of amorphous and crystalline carbohydrates and an increase in aromatic and carbonyl functionality in lignin. The position-resolved spectral data revealed that the fungi initiated degradation in earlywood, and that earlywood remained more extensively degraded than latewood even in advanced decay stages. Apart from differences in mass losses, the two fungi produced similar spectral changes in a similar spatial pattern. The results show that near infrared imaging is a useful tool for analyzing brown rot decayed wood and may be used to advance our understanding of fungal degradative processes.

Biological Durability of Acetylated Hornbeam Wood with Soil Contact in Hungary

This test aimed to discover if industrially acetylated hornbeam can tolerate real-field conditions in Hungary, where various microorganisms can attack the wood separately or cooperatively. Untreated samples accompanied the modified wood to assess the degradation capacity of the soil. The test also focused on weather parameters, the Scheffer index, and soil properties. The untreated stakes showed insect damage, soft rot decay, white rot decay, wasp stripping, moss, and cracks. All of the beech and hornbeam stakes broke after 3.5 years, and the last Scots pine sapwood stakes broke after 6 years. To date, acetylated hornbeam exhibits stronger resistance than untreated hornbeam, beech, and Scots pine sapwood. The acetylated hornbeam stakes showed no decay after 6 years of exposure, and they became dry shortly after being taken from the soil. Acetylated hornbeam stake number 7 had superficial brown rot decay after 18 months, which gradually worsened over the years. The Fourier transform infrared spectroscopy analysis revealed that this stake had lower acetyl content. It was associated with hornbeam wood; it had a wet pocket or a part that was not as permeable and achieved a lower grade of acetylation.

Combination of Sodium Bicarbonate (SBC) with Bacterial Antagonists for the Control of Brown Rot Disease of Fruit.

Simultaneous treatment with antagonistic bacteria Bacillus amylolquefaciens (SF14), Alcaligenes faecalis (ACBC1), and the food additive sodium bicarbonate (SBC) to control post-harvest brown rot disease caused by Monilinia fructigena, and their effect on the post-harvest quality of nectarines were evaluated. Four concentrations of SBC (0.5, 2, 3.5, and 5%) were tested. Results showed that bacterial antagonists displayed remarkable compatibility with different concentrations of SBC and that their viability was not affected. The results obtained in vitro and in vivo bioassays showed a strong inhibitory effect of all treatments. The combination of each bacterial antagonist with SBC revealed a significant improvement in their biocontrol efficacies. The inhibition rates of mycelial growth ranged from 60.97 to 100%. These results also indicated that bacterial antagonists (SF14 or ACBC1) used at 1 × 108 CFU/ mL in combination with 2, 3.5, or 5% SBC significantly improved the control of M. fructigina by inhibiting the germination of spores. Interestingly, disease incidence and lesion diameter in fruits treated with SF14, ACBC1 alone, or in combination with SBC were significantly lower than those in the untreated fruits. In vivo results showed a significant reduction in disease severity ranging from 9.27 to 64.83% compared to the untreated control, while maintaining the appearance, firmness, total soluble solids (TSS), and titratable acidity (TA) of fruits. These results suggested that the improved disease control by the two antagonistic bacteria was more likely due to the additional inhibitory effects of SBC on the mycelial growth and spore germination of the pathogenic fungus. Overall, the combination of both bacteria with SBC provided better control of brown rot disease. Therefore, a mixture of different management strategies can effectively control brown rot decay on fruits.

Fungal Degradation of Extractives Plays an Important Role in the Brown Rot Decay of Scots Pine Heartwood.

Scots pine heartwood is known to have resistance to wood decay due to the presence of extractives, namely stilbenes and resin acids. However, previous studies have indicated that these extractives are degradable by wood decaying fungi. This study aimed to investigate the relationship between extractive degradation and heartwood decay in detail and to gain insight into the mechanisms of extractive degradation. Mass losses recorded after a stacked-sample decay test with brown rot fungi showed that the heartwood had substantial decay resistance against Coniophora puteana but little resistance against Rhodonia placenta. Extracts obtained from the decayed heartwood samples revealed extensive degradation of stilbenes by R. placenta in the early stages of decay and a noticeable but statistically insignificant loss of resin acids. The extracts from R. placenta-degraded samples contained new compounds derived from the degraded extractives: hydroxylated stilbene derivatives appeared in the early decay stages and then disappeared, while compounds tentatively identified as hydroxylated derivatives of dehydroabietic acid accumulated in the later stages. The degradation of extractives was further analysed using simple degradation assays where an extract obtained from intact heartwood was incubated with fungal mycelium or extracellular culture fluid from liquid fungal cultures or with neat Fenton reagent. The assays showed that extractives can be eliminated by several fungal degradative systems and revealed differences between the degradative abilities of the two fungi. The results of the study indicate that extractive degradation plays an important role in heartwood decay and highlight the complexity of the fungal degradative systems.

Non-enzymatic modification of the crystalline structure and chemistry of Masson pine in brown-rot decay

Masson pine undergoes rapid degradation by brown-rot fungi, but how the fungus alters the microstructure of Masson pine cell wall is still unclear. In this study, Masson pine samples were incubated with Gloeophyllum trabeum to aid in characterizing changes in the crystalline structure of cellulose and chemical composition of wood in brown-rot decay. Fungal action resulted in an initial increase in wood cellulose crystallinity and crystallite width because of early removal of the more amorphous celluloses, followed by a decrease in crystallinity and crystallite size. All data suggest that hemicellulose, amorphous cellulose and crystalline cellulose are sequentially depolymerized via a non-enzymatic pathway, concurrent with early-stage changes in the rearrangement of cellulose chains and the diffusion of depolymerized less-crystalline polysaccharides out of the cell wall. Our work provides insight into the role of a non-enzymatic system in brown-rot decay as well as its potential application in lignocellulose preservation and biorefineries.

Effect of photodegradation on fungal colonization on wood during initial stage of brown-rot decay

Abstract Photodegradation and decay may happen simultaneously on wood under many exposure conditions. The aim of this study was to explore the effect of photodegradation on fungal colonization during initial stage of brown-rot decay of wood. For this purpose, southern pine (Pinus spp.) wood was exposed to accelerated UV weathering for different durations, and then decayed by a brown-rot fungus (Gloeophyllum trabeum). The changes in wood microstructure, chemical composition, surface color, crystallinity, fungal colonization pathways, and photodegradation products after weathering and decay were evaluated and characterized. The results showed that both weathering and decay led to obvious color change on wood surface. The photodegradation of wood resulted in the formation of cracking in cell wall, thus creating new voids. The photodegradation products, which mainly consisted of phenols, diterpenoid acids, and other lignin derived compounds, appeared in the cell lumen. During the initial stage of brown-rot decay, fungal hyphae invaded into wood through inherent voids such as ray cells, axial tracheids, and pits, and completed the initial colonization after 20 days. After photodegradation, hyphae could also invade wood from the new voids, and the acidic photodegradation products promoted the non-enzymatic degradation process of brown-rot. However, lignin derived compounds seemed to inhibit the further activity of decay fungi.

Fomitopsis betulina . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Fomitopsis betulina . Sporophores of this fungus are found on both living and dead trees, where the fungus causes a brown-rot decay of heartwood, eventually reducing the substratum to a red-brown friable mass. Some information on its associated organisms and substrata, dispersal and transmission, habitats and conservation status is given, along with details of its geographical distribution (Asia (China (Gansu, Heilongjiang, Jilin, Nei Mongol Autonomous Region, Shaanxi, Sichuan, Xinjiang Autonomous Region, Yunnan), India (Meghalaya, Uttarakhand), Iran, Japan, Kazakhstan (Akmola, East Kazakhstan, Kostanay, North Kazakhstan), Nepal, Russia (Altai Krai, Altai Republic, Amur Oblast, Chelyabinsk Oblast, Irkutsk Oblast, Kamchatka Krai, Khabarovsk Krai, Khanty-Mansi Autonomous Okrug, Krasnoyarsk Krai, Novosibirsk Oblast, Omsk Oblast, Primorsky Krai, Sakha Republic, Sakhalin Oblast, Sverdlovsk Oblast, Tomsk Oblast, Tyumen Oblast, Yamalo-Nenets Autonomous Okrug, Zabaykalsky Krai), South Korea, Uzbekistan), Central America (Belize, Panama), Europe (Åland Islands, Andorra, Austria, Belarus, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Isle of Man, Italy, Latvia, Lithuania, Luxembourg, Netherlands, Norway, Poland, Portugal, Romania, Russia (Bryansk Oblast, Chuvash Republic, Ivanovo Oblast, Kaliningrad Oblast, Kaluga Oblast, Kirov Oblast, Komi Republic, Kostroma Oblast, Krasnodar Krai, Kursk Oblast, Leningrad Oblast, Mari El Republic, Moscow Oblast, Murmansk Oblast, Nizhny Novgorod Oblast, Orenburg Oblast, Perm Krai, Pskov Oblast, Republic of Bashkortostan, Republic of Dagestan, Republic of Karelia, Republic of Mordovia, Republic of Tatarstan, Ryazan Oblast, Samara Oblast, Saratov Oblast, Smolensk Oblast, Tula Oblast, Tver Oblast, Udmurt Republic, Vladimir Oblast, Yaroslavl Oblast), Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine, UK), North America (Canada (Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Ontario, Prince Edward Island, Quebec, Yukon Territory), USA (Alabama, Alaska, Arkansas, California, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, Virginia, Washington, West Virginia, Wisconsin)), South America (Argentina, Colombia)).

Prediction model based on chemical composition change for the mechanical degradation of Korean pine (Pinus koraiensis) after brown-rot fungi (Gloeophyllum trabeum) invasion

Abstract In order to predict the mechanical properties of Korean pine after brown-rot decay based on its chemical composition change, 252 samples were prepared and exposed to a 14-week accelerated laboratory decay test using the brown-rot fungus Gloeophyllum trabeum. The mass loss, parallel-to-grain compressive strength, parallel-to-grain tensile strength and bending strengths were tested. Then chemical components and scanning electron micrograph analysis were conducted every two weeks. Results indicated that the mass loss rates of the samples increased with the increasing decay time and were negatively correlated with the sample volume. The strength loss rates were positively correlated with the decay time and mass loss rates. After 14 weeks the average strength loss rates of the parallel-to-grain compressive, tensile and bending samples reached 32%, 41% and 41%, respectively. Strengths degradation was found sensitive to the change of cellulose and hemicellulose contents. Further, mathematical regression models were proposed based on the content changes of the cellulose and hemicellulose to quantitatively predict the degradation of the strengths of Korean pine after brown-rot decay.