Distribution of Myxomycetes on coarse woody debris of <Emphasis Type="Italic">Pinus densiflora</Emphasis> at different decay stages in secondary forests of western Japan

The relationship between myxomycete species and the decay stage of wood of Pinus densiflora coarse woody debris was investigated in warm temperate secondary forests of western Japan. The number of species and species diversity of the myxomycete community reached the maximum on moderately decayed wood. The 25 dominant species recorded from 8 or more samples of the total 1530 samples were arranged in order of the succession index corresponding to the stage of decay. Species on slightly decayed hard pine wood were characterized by Stemonitis splendens, Enerthenema papillatum, and Physarum viride, whereas species of Cribrariaceae were found on brittle decayed soft wood increasing abundance according to the decay stages. Most of the species occurred where there was sufficient moisture preserved in the environment of the decaying wood, although S. splendens specifically emerged in low-moisture environments. Because the myxomycete species had preference to different decay stages of wood, it appears that they change sequentially during myxomycete community succession on dead pine wood according to the progression of decay.     

Association between myxomycetes and the decay stage of coarse woody debris in an evergreen broadleaf forest in warm temperate Japan

Myxomycetes inhabit coarse woody debris in varying stages of decay; however, their ecology in the dead wood of evergreen broadleaf trees is not well known. In this study, we examined the relationships between myxomycete species and the decay stage of wood from fallen trees in an evergreen broadleaf forest in Japan. Myxomycete species richness and abundance were calculated for eight stages of decay in fallen logs, according to the appearance and wood hardness of log portions. A total of 70 myxomycete species (including varieties) were found on the logs. Moderately decayed wood was the preferred habitat of myxomycetes (57 species; 81% of the total) and most species inhabited moist decayed wood. Analysis by nonmetric multidimensional scaling enabled the differentiation of myxomycete assemblages, with five groupings recognized across the progression of decay. Forty-two species preferred a particular decay stage, represented by the decay index. Physarum viride and Stemonitis splendens particularly preferred the less-decayed wood and Stemonitopsis typhina var. similis especially inhabited the well-decayed wood. Species from the order Physarales dominated the less-decayed wood, whereas Trichiales and Liceales species dominated the softer well-decayed wood. Myxomycetes diversity was high in and varied among logs with various stages of decay in a typical Japanese evergreen forest.     

Influence of harvest gaps and coarse woody material on click beetles (Coleoptera: Elateridae) in Maine’s Acadian forest

In order to maintain biodiversity in forests, it has been recommended that harvests be designed after patterns of natural disturbance. Using a long-term study that includes harvest treatments designed to emulate tree-fall gap disturbances in Maine’s Acadian forest, we examined how the species richness, abundance, diversity, and assemblage similarity of click beetles inhabiting coarse woody material (CWM) were affected by gap harvesting and CWM characteristics (diameter, degree of decay, and type of wood). There were few differences in beetle assemblages between 0.07 and 0.12 ha harvest gap treatments. Four of the most common species had higher abundances under a closed forest canopy than within harvest gaps. Species richness and total abundance were higher in CWM that had larger diameters and were more decayed. Species assemblages also differed with the degree of wood decomposition. Diversity was higher in CWM from softwood trees than hardwood trees. Results from this study suggest that small (<0.2 ha) harvest gaps with living trees retained throughout the gap can maintain click beetle assemblages similar to that of an unharvested forest. Forest managers also need to address the temporal continuity of CWM, including different types of wood (hardwood and softwood), a range of decay conditions, and a range of diameter classes, especially larger diameters (>35 cm).     

Wood decomposing abilities of diverse lignicolous fungi on nondecayed and decayed beech wood

We tested the decay abilities of 28 isolates from 28 lignicolous fungal species (Basidiomycota, Ascomycota and Zygomycota) with the pure culture test. We used beech wood powder in varying moisture conditions and decay stages (nondecayed, intermediately decayed and well decayed) as substrates. The weight loss in wood powder was -0.2-17.8%. Five isolates of Basidiomycota (Bjerkandera adusta, Mycena haematopus, Omphalotus guepiniformis, Trametes hirsuta, Trametes versicolor) caused high weight losses in nondecayed wood. We detected significant effects of decay stage on weight loss in wood in most isolates tested, whereas moisture content rarely had an effect on weight loss. Among Basidiomycota and Xylariaceae in Ascomycota weight loss was greater for nondecayed wood than for intermediately and well decayed wood. In contrast four isolates in Ascomycota (Scytalidium lignicola, Trichoderma hamatum, T. harzianum, T. koningii) caused substantial weight loss in intermediately and well decayed wood, although they rarely caused weight loss in nondecayed wood. Zygomycota caused low weight loss in wood. Wood decay stages also affected decomposition of wood chemical components. Acid-unhydrolyzable residue (AUR) decomposition was reduced, whereas holocellulose decomposition was stimulated by some strains of Basidiomycota and Ascomycota in well decayed wood. T. harzianum in particular caused significant weight loss of holocellulose in well decayed wood, although this fungus caused negligible weight loss of both AUR and holocellulose in nondecayed wood. We discuss these changes in the decay patterns of AUR and holocellulose with varying wood decay stages in relation to the role of fungal decomposition of woody debris in forests.     

How to Make a Beetle Out of Wood: Multi-Elemental Stoichiometry of Wood Decay,Xylophagy and Fungivory

The majority of terrestrial biomass is wood, but the elemental composition of its potential consumers, xylophages, differs hugely from that of wood. This causes a severe nutritional imbalance. We studied the stoichiometric relationships of 11 elements (C, N, P, K, Ca, Mg, Fe, Zn, Mn, Cu, Na) in three species of pine-xylem-feeding insects, Stictoleptura rubra, Arhopalus rusticus (Coleoptera, Cerambycidae) and Chalcophora mariana (Coleoptera, Buprestidae), to elucidate their mechanisms of tissue growth and to match their life histories to their dietary constraints. These beetles do not differ from other Coleoptera in their absolute elemental compositions, which are approximately 1000 (N), 100 (P, Cu) and 50 (K, Na) times higher than in dead but undecayed pine wood. This discrepancy diminishes along the wood decay gradient, but the elemental concentrations remain higher by an order of magnitude in beetles than in highly decayed wood. Numerical simulation of the life history of S. rubra shows that feeding on nutrient-poor undecayed wood would extend its development time to implausible values, whereas feeding on highly decomposed wood (heavily infected with fungi) would barely balance its nutritional budget during the long development period of this species. The changes in stoichiometry indicate that the relative change in the nutrient levels in decaying wood cannot be attributed solely to carbon loss resulting from decomposer respiration: the action of fungi substantially enriches the decaying wood with nutritional elements imported from the outside of the system, making it a suitable food for wood-eating invertebrates.     

Diffusion and seasonal dynamics of O2 in woody debris from the Pacific Northwest,USA

O₂ is an important regulator of physiological processes involved in the decomposition of woody debris, yet O₂ levels and diffusion rates within decomposing logs are largely unknown. We examined how O₂ diffusion rates in decayed and sound wood varied with moisture and density, and we compared predicted with observed seasonal changes in oxygen concentration in logs in a Pacific Northwest old-growth Pseudotsuga menziesii forest. In the laboratory, the oxygen diffusion coefficient (D_O2) was determined in the longitudinal and radial (or tangential) directions on wood cores of varying moisture content and density. In the field, O₂ was measured in tubes inserted to three radial depths (2, 6 and 15 cm) within logs of two species (Pseudotsuga menziesii and Tsuga heterophylla) and five decay classes (where class 5 = most decayed). In both the radial and longitudinal directions, D_O2 increased exponentially as the air filled pore space (AFPS) increased and as density decreased. In the field, mean O₂ concentrations in logs were not significantly different between species. Mean O₂ concentrations were significantly lower in the least decayed logs as compared to the most decayed logs. Mean O₂ concentrations decreased with radial depth only in decay class two logs. Seasonal O₂ levels did not consistently vary with log moisture, respiration, or air temperature. The comparison of the results from a model that assumes oxygen diffuses only in the radial direction to field data indicates that laboratory measurements of oxygen diffusion may underestimate field oxygen concentrations. Cracks, insect galleries and other passages in decayed logs, and longitudinal oxygen diffusion may account for this discrepancy. In the field, log oxygen concentrations were rarely as low as 2%, indicating anaerobic conditions may not be as common in logs as we previously thought. Oxygen limitations on decomposition may occur in relatively sound and/or water soaked wood, but probably not in decayed logs in a terrestrial setting.     

古田山国家级自然保护区木腐真菌物种多样性及分布

木腐真菌是微生物的一个重要类群, 主要以倒木为生长基质, 通过产生各种水解酶将倒木的纤维素、木质素和半纤维素分解为小分子物质, 对促进森林生态系统中的营养物质循环发挥着重要的生态功能。于2016年8月在浙江古田山国家级自然保护区开展的木腐真菌野外调查, 利用形态学和DNA序列分析对采集的标本进行了物种鉴定, 并分析了木腐真菌的物种组成和地理成分。在采集的158份标本中鉴定木腐真菌45属92种, 其中白腐真菌78种, 褐腐真菌14种。古田山的木腐真菌物种区系组成中, 热带-亚热带成分比例最高。在158份木腐真菌标本中, 97份标本采自直径大于10 cm的倒木或树桩上, 分属于76个种, 是木腐真菌生长的主要基质大小类型; 48份标本采自直径为2-10 cm的枝干上, 分属38个种; 13份标本采自直径小于2 cm的枝干上, 分属12种。不同腐烂等级倒木上生长的真菌数量和种类差异明显, 其中一级腐烂倒木上采集到9份标本(7种), 二级腐烂倒木上采集到86份标本(45种), 三级腐烂倒木上49份标本(29种), 四级腐烂倒木上14份标本(14种)。结果表明, 林分中倒木直径大小和腐烂程度是影响木腐真菌生长与分布的重要因子。     

Wood-inhabiting fungi on fallen logs of Norway spruce: relations to forest management and substrate quality

A survey of the patterns of wood decaying fungi as to occurrence of sporocarps on naturally fallen logs of Norway spruce ( Picea abies ) was undertaken in two nearby forest stands with different histories of management. One stand was an old-growth forest with few signs of logging, and the other stand was selectively logged 60–80 years ago. Altogether 118 species were found. Forest management had a negative impact on the species diversity. Newly fallen and weakly decayed logs in a natural forest had a higher species richness, more red-listed species, as well as more indicator species compared to similar logs in a managed forest. The importance of dead wood for species diversity of wood inhabiting fungi was clearly demonstrated. Presence of logs in later stages of decomposition increased the total species number in a natural forest stand with 42 (63 %), compared to a survey of only newly fallen and weakly decayed logs. Presence of logs in later stages of decomposition also increased the diversity of the species pool colonising newly fallen and weakly decayed logs. The highest number of fruiting species was found on intermediately decayed logs and on logs lying in contact with the ground. The fungal gradient as revealed in a DCA ordination was primarily related to decay. A successional pathway based on the primary decayer Fomitopsis pinicola was not detected.     

mRNA abundance changes during flagellar regeneration in Chlamydomonas reinhardtii.

Flagellar amputation in Chlamydomonas reinhardtii induces the accumulation of a specific set of RNAs, many of which encode flagellar proteins. We prepared a cDNA clone bank from RNA isolated from cells undergoing flagellar regeneration. From this bank, we selected clones that contain RNA sequences that display several different patterns of abundance regulation. Based on quantitation of the relative amounts of labeled, cloned cDNAs hybridizing to dots of RNA on nitrocellulose filters, the cloned sequences were divided into five regulatory classes: class I RNAs remain at constant abundance during flagellar regeneration; classes II, III, and IV begin to increase in abundance within a few minutes after deflagellation, reach maximal abundance at successively later times during regeneration, and return to control cell levels within 2 to 3 h; and class V RNA abundance decreases during flagellar regeneration. Alpha- and beta-tubulin mRNAs are included in regulatory class IV. The abundance kinetics of alpha-tubulin mRNAs differ slightly from those of beta-tubulin mRNAs. The availability of these clones makes possible studies on the mechanisms controlling the abundance of a wide variety of different RNA species during flagellar regeneration in Chlamydomonas.     

The Effect of a Copper Smelter Emissions on the Stock and Decomposition of Coarse Woody Debris in Spruce and Fir Woodlands

We have studied the share of coarse woody debris (CWD) reserves at different decay classes in the spruce and fir woodland within the impact area of aerial pollution from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast). Control and impact areas slightly differ in total reserves and number of trunks of CWD (sum of standing and fallen dead wood). However, the number of CWD tends to grow in proximity to the plant. The mechanisms involved in CWD-reserve formation differ between impact and control sites. A larger number of relatively thin trunks prevail in CWD reserves of impact sites when compared to the lower number of thick trunks at control sites. The CWD share of 30% in the total number of dead and living trees did not differ across pollution loads. However, the share of CWD reserves in total stock is 1.9 times higher near the plant than at the control site. The share of logs at the initial stages of decomposition (first and second decay classes) is 3.2 times higher in terms of CWD number and 4.2 times higher in terms of CWD reserves than at the control sites. This points to the strong inhibition of CWD decomposition. The pattern of decay classes of all sizes of fallen trees significantly differs in volume across pollution zones.     

Changes in ant communities along an age gradient of cocoa cultivation in the Oumé region,central Côte d'Ivoire

We identified the extent to which ant diversity occurs despite conversion of forests into cocoa plantations by examining the communities across four age classes of plantations (classes I–IV with increasing age from 0–5 to 21–40 years) and in their original forests. An extensive sampling protocol consisting of pitfall trapping, leaf litter sampling, soil sampling and hand sampling was used to characterize ant species richness and composition in three replicates of each age class and in the remaining forest patches. A total of one hundred ant species was found in all habitats combined. While the forest was the richest habitat (73 species), species richness in the different plantation age classes varied as follows (sorted in descending order): class IV (69 species) > class III (57 species) > class I (52 species) > class II (43 species). Age gradient was thus significantly positively correlated with mean species richness and with the relative abundance of some subfamilies. The species composition differed greatly between some plantation age classes and the forest. The two youngest cocoa age classes (I and II) were most dissimilar to the forest. In contrast, forest ants were well represented in the old cocoa age classes (III and IV). Three functional guilds (generalist predators, specialist predators and territorially dominant arboreal species) were in their relative abundance significantly correlated to the age gradient. Overall, cocoa cultivations retaining a floristically diverse and structurally complex forest structure are a suitable management system for the conservation of ant species of the formerly forested habitats.     

Influence of snag characteristics on saproxylic beetle assemblages in a south Swedish beech forest

Effects of snag characteristics on saproxylic beetles were studied in an area of managed beech forest in southern Sweden. A snag survey was combined with a beetle survey using 30 small window traps directly attached to beech snags. The total number of species was lower in the snags which were most decayed than in the three younger decay classes, while the number of red-listed species remained the same regardless of the stage of decay. The number of fresh wood species declined and the number of rot hole species increased with increasing snag decay. The diversity of fungicolous and decayed wood species peaked at the intermediate stage of decay in the snags. CCA ordination confirmed that the stage of decay in the snags was most important for species composition, followed by sun exposure. There were no general differences in species density and composition between managed and unmanaged stands. Our study suggests that most species are able to find suitable habitat within a radius of a few kilometres and that the total amount of habitat in an unfragmented forest area is more important for species diversity than the spatial distribution of this habitat. Our data also shows that species diversity increases with habitat diversity. Snags formed from giant beech trees seem to be particularly important for rare species living in rot holes. We conclude that for a high species diversity there is a requirement for snags in different stages of decay, size and degree of sun exposure.     

Effects of decay classes and diameter classes on physico-chemical properties of Pinus koraiensis log in a typical mixed broadleaved-Korean pine forest

AimsLog is an important component for most of forest ecosystems. It plays crucial roles in maintaining soil fertility, sustaining biodiversity and cycling of carbon (C) and nutrient. However, physico-chemical properties of logs vary with decay classes and diameter classes. Our objective was to study effects of decay classes and diameter classes on physico-chemical properties of logs in a typical mixed broadleaved-Korean pine forest in northern China.MethodsIn this study, logs of Pinus koraiensis were chosen as it was the constructive species in the typical mixed broadleaved-Korean pine forest. Logs of P. koraiensis at each decay classes (I-V) were divided into four diameter classes, including diameter class i ≤ 10.0 cm, diameter class ii: 10.1-30.0 cm, diameter class iii: 30.1-50.0 cm, and diameter class iv > 50.0 cm. Then, we explored effects of different decay classes, diameter classes and their interactions on the physico-chemical properties of logs for both the heartwood and sapwood.Important findings The results showed that the physico-chemical properties of heartwood and sapwood generally exhibited similar variations. Their moisture content both increased with an increasing decay class, whereas wood density both decreased with an increased decay class and diameter class. The carbon concentrations of the sapwood showed a trend of gradual increasing during decomposition, and there was an accumulation in nitrogen (N) and phosphorus (P) concentrations of the heartwood and sapwood with an increased decay class, simultaneously. Only N and P concentrations of the heartwood increased and then decreased with an increasing diameter class. The cellulose content decreased with an increasing decay class. In contrast to the cellulose, the lignin content increased with an increased decay class. However, cellulose and lignin contents exhibited no distinct trend among diameter classes. The moisture content of logs had a significant positive correlation with C, N, P concentrations and lignin content (except P concentrations of the heartwood), but had a significant negative correlation with the cellulose content (p< 0.05). The wood density was negatively correlated with C, N, P concentrations and the lignin content, but it was positively correlated with the cellulose content (p< 0.05). Therefore, physico-chemical properties of logs had unique patterns along both decay classes and diameter classes, and the physical properties of logs (the moisture content and wood density) were important factor affecting the variations of their chemical contents.     

腐烂等级、径级对典型阔叶红松林红松倒木物理化学性质的影响

倒木是森林生态系统的重要组成部分, 在地力维护、生物多样性保持以及碳(C)和养分循环等方面具有重要意义, 但倒木物理化学性质随其腐烂等级和径级而变化。为了深入理解腐烂等级和径级对倒木物理化学性质的影响, 该研究以典型阔叶红松林的建群种——红松(Pinus koraiensis)的倒木为研究对象, 将其每个腐烂等级(I-V)下的倒木分为4个径级(径级i ≤ 10.0 cm、径级ii 10.1-30.0 cm、径级iii 30.1-50.0 cm、径级iv >50.0 cm), 研究了不同腐烂等级、径级及两者交互作用对倒木心材和边材物理化学性质的影响。结果表明: 心材和边材具有相似的变化规律。倒木心材和边材含水率随着腐烂等级增加而增加, 而木材密度随腐烂等级和径级的增加均呈下降趋势; 边材C含量以及心材和边材的氮(N)、磷(P)含量随腐烂等级增加呈上升趋势, 心材N、P含量随径级增加呈先增加后减少的趋势; 纤维素含量随腐烂等级增加呈下降趋势, 而木质素含量呈上升趋势, 纤维素和木质素含量随径级增加没有明显变化规律。倒木含水率与C、N、P、木质素含量(除心材P含量)显著正相关, 与纤维素含量显著负相关; 木材密度与C、N、P、木质素含量显著负相关, 与纤维素含量显著正相关。由此可见, 倒木物理化学性质受不同腐烂等级和径级的影响有各自的变化规律, 且倒木的物理性质(含水率和木材密度)是影响化学含量变化的重要因素。     

Succession of saproxylic beetles associated with decomposition of boreal white spruce logs

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Inhibition and Stimulation Effects in Communities of Wood Decay Fungi: Exudates from Colonized Wood Influence Growth by Other Species

The effects of exudates from uncolonized and from partly decayed beech wood on the extension rates of 16 later stage decay fungi were investigated. The partly decayed wood had been colonized by the pyrenomycete Eutypa spinosa, or the basidiomycetes Fomes fomentarius, Stereum hirsutum, and Trametes versicolor, all known as common early decay agents in European beech forests. Sterilized wood pieces were placed onto 0.5% malt agar, opposite to small agar plugs containing the test fungi. The latter showed very variable and species-specific growth responses to the various wood types. The presence of uncolonized wood stimulated extension rates in many species, whereas the four previously decayed wood types had variable stimulatory or inhibitory effects. Wood decayed by S. hirsutum resulted in reduced extension rate, delayed growth, or total inhibition in the majority of species, thus it is suggested that this species uses secondary metabolites in a defensive strategy. A single species was, however, stimulated in the presence of S. hirsutum-decayed wood. In contrast, the presence of wood decayed by F. fomentarius was stimulatory to 45% of the species. The other previously decayed wood types generally resulted in more variable responses, depending upon species. The results are discussed in an ecological context and it is suggested that the exudates from the partly decayed wood that are responsible for the reported effects may function as infochemicals, structuring microbial communities in wood.     

Fungal wood decomposer activities influence community structures of myxomycetes and bryophytes on coarse woody debris

Dead wood is an important habitat for forest organisms, and wood decay fungi are the principal agents determining the dead wood properties that influence the communities of organisms inhabiting dead wood. In this study, we investigated the effects of wood decomposer fungi on the communities of myxomycetes and bryophytes inhabiting decayed logs. On 196 pine logs, 72 species of fungi, 34 species and seven varieties of myxomycetes, and 16 species of bryophytes were identified. Although white rot was the dominant decay type in sapwood and heartwood, brown and soft rots were also prevalent, particularly in sapwood. Moreover, white rot and soft rot were positively and brown rot negatively correlated with wood pH. Ordination analyses clearly showed a succession of cryptogam species during log decomposition and showed significant correlations of communities with the pH, water content, and decay type of wood. These analyses indicate that fungal wood decomposer activities strongly influence the cryptogam communities on dead wood.     

The community structures of the coniferous and deciduous dead wood‐dwelling arthropods in Korea

We examined the structure of the arthropod community among deciduous and coniferous dead woods along the process of wood decay. We collected dead wood‐dwelling arthropods from April 2010 to October 2011 by using a vacuum aspirator and an electric chain saw in three areas (Mt. Woonak, Mt. Wolchul, Mt. Jingang) in Korea. We identified them to species levels and classified them into functional groups. We collected 8792 arthropods (5 classes, 20 orders, 58 families, and 93 species). The species richness and abundance of arthropods increased with the progress of decay in dead woods. The evenness index seemed to be shown at a lower value at late decay stage than at early‐ and mid‐decay stages. The diversity index (H′) in conifers was lower than that in deciduous dead woods at the early decay stage but this situation was reversed at the late decay stage. Arthropod communities of functional groups, except the xylophagous insects, did not differ in the variables, but the proportion of xylophagous insects increased as the decay stages progressed. The abundance of arthropods and xylophagous was statistically significantly different. The patterns generated by non‐metric multidimensional scaling in the overall arthropod community composition revealed that the species composition between study areas were significantly different. We confirmed that dead woods play very important roles as arthropods' habitats. Thus, we suggest that the role of dead woods should be emphasized in the management of forest ecosystems.     

Succession in myxomycete communities on dead <Emphasis Type="Italic">Pinus densiflora</Emphasis> wood in a secondary forest in southwestern Japan

Changes in myxomycete communities and species were investigated over an 8-year period in relation to the decay state of dead Pinus densiflora Siebold & Zucc. wood on which myxomycete fruiting bodies occurred. The study was carried out during three different seasons in a pine forest in southwestern Japan. A total of 44 species and seven varieties of myxomycetes were recorded. The species richness and diversity of the annual myxomycete communities did not clearly change in relation to the series of years, but the percent similarity of the myxomycete community from the beginning of the survey through the following years tended to decrease every season. The ordination of the annual communities, analyzed using non-metric multidimensional scaling (NMDS), indicated that seasonal factors on the first axis and the decay state of the wood on the second axis were significantly related. Species colonization patterns were arranged using succession indices and the distribution of certain species at particular times of the year: Arcyria ferruginea, A. obvelata, Lamproderma arcyrionema, and Physarum viride early in the year and Stemonitopsis hyperopta, Cribraria intricata, Lindbladia cribrarioides, Lamproderma columbinum, Tubifera ferruginosa, and Trichia verrucosa later on. Changes in the relative abundance of colony sizes of several species showed annual trends. Species using slightly decayed wood at the beginning were replaced by those using more brittle wood as the years progressed. Myxomycete succession on dead wood changed through time as the wood decayed, based on species preferences for particular decay stages.     

Fungal decomposition of woody debris of Castanopsis sieboldii in a subtropical old-growth forest

Fungi, especially basidiomycetes, are the primary agents of woody debris decomposition in terrestrial forest ecosystems. However, quantitative data regarding the abundance and decay activity of wood-inhabiting fungi are lacking, especially for tropical and subtropical areas. This study demonstrates the dynamics of decay columns of wood-inhabiting fungi within decaying woody debris of Castanopsis sieboldii and the wood decay activities of those fungi in a subtropical natural forest. Among six basidiomycetes and two ascomycetes observed as sporocarps on fallen boles of C. sieboldii, Microporus affinis was most abundantly observed in terms of frequency of sporocarps and as percentage area of decay columns within cross-sections of boles, especially those in the early stages of decomposition. In decay columns of M. affinis, both acid-unhydrolyzable residue (AUR) and holocellulose decayed simultaneously, and wood relative density decreased to 45.8% of that of fresh C. sieboldii wood. A pure culture decay test under laboratory conditions showed that M. affinis was a strong decomposer of AUR and holocellulose. These results suggest that M. affinis has a central role in lignocellulose decomposition of wood of C. sieboldii in the early stages of decomposition.