Community structure of polypores (Basidiomycota) in Andean alder wood in Argentina: Functional groups among wood‐decay fungi?

Abstract The polypores (Aphyllophorales s.l., Basidiomycota) are very effective wood decayers. Different species differ in their capacity to decay wood; therefore, many functionally different species can be found decaying different substrate conditions (decay stages and log diameter). This study aimed to describe the structure of the wood‐decay polypore communities that occur on different states of wood of the Andean alder (Alnus acuminata) within Argentina and to identify groups of polypore species that share the same substrate condition, and thus might have a similar functional role in the decay processes. We found 16 polypore species, among which Trametes versicolor, Bjerkandera adusta and Trametes cubensis were dominant species, showing the highest relative frequency in alder wood. Species richness was lower on trunks of living trees and higher on dead branches. Based on preferential occurrence on different wood conditions, a cluster analysis distinguished three groups, each of them containing one of the three dominant species. This corresponds to the situation of other groups of organisms, where each functional type consists of a dominant species that accounts for most of the ‘function’ and several subordinate species with similar functions. Albeit preliminary, our results provide a formal classification of wood‐decay fungi into functional types.     

Chemical Composition of Cacti Wood and Comparison with the Wood of Other Taxonomic Groups

The aims of this study were to determine the wood chemical composition of 25 species of Cactaceae and to relate the composition to their anatomical diversity. The hypothesis was that wood chemical components differ in relationship to their wood features. The results showed significant differences in wood chemical compounds across species and genera (P < 0.05). Pereskia had the highest percentage of lignin, whereas species of Coryphantha had the lowest; extractive compounds in water were highest for Echinocereus, Mammillaria, and Opuntia. Principal component analysis showed that lignin proportion separated the fibrous, dimorphic, and non‐fibrous groups; additionally, the differences within each type of wood occurred because of the lignification of the vascular tissue and the type of wall thickening. Compared with other groups of species, the Cactaceae species with fibrous and dimorphic wood had a higher lignin percentage than did gymnosperms and Acer species. Lignin may confer special rigidity to tracheary elements to withstand desiccation without damage during adverse climatic conditions.     

Feeding ecology and phylogenetic structure of a complex neotropical termite assemblage,revealed by nitrogen stable isotope ratios

1. In the current ecological classification of termites, four feeding groups (I–IV) are recognised, corresponding to a gradient of decomposition from sound wood to highly mineralised organic matter in the soil. 2. Nitrogen stable isotopes (hereafter δ¹⁵N) were used to place termites from French Guiana rainforests along a wood‐soil decomposition gradient, to test (i) whether feeding group assignation based on morphological characters was accurate and actually represented diet specialisation thresholds, and (ii) to what extent the dietary specialization of species is explained by phylogeny (phylogenetic autocorrelation). 3. δ¹⁵N values vary over a range of 13‰, suggesting that diet diversification contributes to the high species diversity in French Guiana. δ¹⁵N values span a similar interval in all Termitidae subfamilies. Ranges of different subfamilies broadly overlap, although each of them diversified preferentially on one side of the wood‐soil decomposition gradient. Congeneric species share similar feeding habits, whereas distant species tend to feed on distinct substrates. 4. Feeding groups did not completely match stable isotope data: there was no discontinuity between Groups III and IV, and no correlation between anatomical criteria used to distinguish these groups and δ¹⁵N values. Nor was there any consistent difference in δ¹⁵N values between wood feeders of the families Rhinotermitidae (Group I) and Termitidae (Group II). We also suggest that species feeding outside the wood‐soil gradient should be distinguished for their peculiar feeding requirements.     

Stand type is more important than red wood ant abundance for the structure of ground‐dwelling arthropod assemblages in managed boreal forests

• 1 The relationships between red wood ants (Formica rufa group) and other ground‐dwelling arthropods were studied in young managed forests stands in Eastern Finland. The main objectives were: (i) to test the influence of stand type (dominant tree species; age: sapling versus pole stage) and numbers of red wood ants on the occurrence of other ground‐dwelling arthropods and (ii) to study the occurrence of red wood ants versus other arthropods on a distance gradient from ant mounds. We used pitfall traps set in 5–14‐year‐old sapling stands and 30–45‐year‐old pole‐stage stands of Scots pine (Pinus sylvestris L.) and birch (Betula spp.) forests.
• 2 Pitfall trap catches of red wood ants did not vary significantly between the forest stand types, although some groups of other arthropods showed clear responses to stand type (e.g. catches of other Formicinae and Gnaphosidae were higher in sapling stands than in pole‐stage stands). The number of red wood ants clearly explained less of the variation in assemblages of other ground‐dwelling arthropods than the forest stand type.
• 3 Red wood ant numbers decreased significantly with distance from the mounds, but the other ground‐dwelling arthropods were insensitive to this gradient or even showed a preference for proximity to ant mounds and high ant activity.
• 4 The results obtained in the present study suggest that wood ants do not have strong effects on several other ground‐dwelling arthropod groups in young managed forests other than in the immediate vicinity of their mounds.

     

Colonisation of experimentally immersed wood in south eastern Australia: responses of feeding groups to changes in riparian vegetation

We investigated macroinvertebrate abundance and functional feeding groups colonising experimentally-positioned woody substrates of different species in streams with three different riparian vegetation types. Native Eucalyptus forest formed a dense closed canopy over our streams; introduced (exotic, alien) pine plantation forest did not fully shade the streams, and grassland streams were completely open, although with woody riparian vegetation well upstream of our sites. Macroinvertebrate assemblages varied taxonomically and functionally with both wood species and riparian vegetation composition. Two specialist feeding groups responded clearly to riparian vegetation: wood gougers were most common in forested streams, and algal grazers in more open streams. Gougers colonised native Eucalyptus wood in preference to alien species. Other feeding groups responses showed complex interactions between vegetation and wood type. Our results indicate the importance of sampling appropriate substrates when assessing questions of this type – if seeking shifts in functional organisation, the substrates on which the feeding groups of interest occur must be sampled. The composition of the riparian strip may influence xylophilous communities as much as the structure (i.e. whether closed or open).     

Wood Decomposition of Cyrilla racemiflora (Cyrillaceae) in Puerto Rican Dry and Wet Forests: A 13‐year Case Study1

We studied the decomposition of Cyrilla racemiflora logs over a 13‐yr period in tropical dry and wet forests in Puerto Rico. The mean mass loss, ratio of soft to hard wood, nutrient concentrations, and the diversity of wood‐inhabiting organisms were greater in logs decomposing in the dry forest than in the wet forest. Termites were also more abundant in the logs collected from the tropical dry forest than the tropical wet forest. High moisture content and a low animal diversity on the logs in the wet forest seem to retard wood decay in this habitat. Wood decay rates in the tropical dry forest can be related to the high diversity of species and functional groups of wood‐inhabiting organisms.     

MORPHOGRAM: A NOVEL DIAGRAM TO ORGANIZE THE TRANSITIVE SECONDARY XYLEM ELEMENTS OF BASAL TOMATO (SOLANUM LYCOPERSICUM) INTERNODES

In the internodal secondary xylem of tomato (Solanum lycopersicum L. cv. Moneymaker) there are five main groups of secondary xylem elements which can be distinguished in wood macerates of basal internodes of the plant. Their top-frequency lengths are distinct: ray parenchyma cells (80 μm); fusiform parenchyma cells and strands (250 μm); vessel members (290 μm); tracheids (350 μm); and fibrous elements (590 μm), although there is overlap in length and morphology. The imperforate axial elements are strikingly diverse and morphologically intergrading, precluding ready classification according to traditional wood anatomical standards. In a novel, more appropriate, flexible categorization the variability in imperforate axial elements is depicted in a morphogram in which pit shape is plotted against cell length and cell morphology. This morphogram organizes the various elements without imposing an absolute classification. It is concluded that the appreciable variation in tomato wood samples results from developmental plasticity. The morphogram elucidates the extent and nature of element variation at the morphological level. Thus, it can be used to record developmental plasticity of wood tissues to assess interplant variation in wood tissue development, as well as intraplant plasticity.     

Quantitative trait locus (QTL) analysis of wood quality traits in <Emphasis Type="Italic">Eucalyptus nitens</Emphasis>

To identify the chromosomal regions affecting wood quality traits, we conducted a genome-wide quantitative trait locus (QTL) analysis of wood quality traits in Eucalyptus nitens. This information is important to exploit the full potential of the impending Eucalyptus genome sequence. A three generational mapping population consisting of 296 progeny trees was used to identify QTL associated with several wood quality traits in E. nitens. Thirty-six QTL positions for cellulose content, pulp yield, lignin content, density, and microfibril angle (MFA) were identified across different linkage groups. On linkage groups (LG)2 and 8, cellulose QTL cluster with pulp yield and extractives QTL while on LG4 and 10 cellulose and pulp yield QTLs cluster together. Similarly, on LG4, 5, and 6 QTL for lignin traits were clustered together. At two positions, QTL for MFA, a physical trait related to wood stiffness, were clustered with QTL for lignin traits. Several cell wall candidate genes were co-located to QTL positions affecting different traits. Comparative QTL analysis with Eucalyptus globulus revealed two common QTL regions for cellulose and pulp yield. The QTL positions identified in this study provide a resource for identifying wood quality genes using the impending Eucalyptus genome sequence. Candidate genes identified in this study through co-location to QTL regions may be useful in association studies.     

Adaptive latitudinal trends in the mandible shape of Apodemus wood mice

Aim Size and shape of the mandible are investigated across the latitudinal range of the European wood mouse (Apodemus sylvaticus), in order to address the relative importance of genetic structure, insularity, and geographical gradient in patterning morphological variation. Results are compared with those on two Asiatic species of wood mice, A. argenteus and A. speciosus. Location The European wood mouse is sampled by a set of trapping localities including both, islands and mainland populations, as well as the four genetic groups identified in previous studies. The localities cover a latitudinal gradient from 55° N to 36° N. Methods Different Fourier methods are applied to the outlines of mandibles and their results compared in the case of A. sylvaticus. All provide similar results and allow a quantification of the size and shape variations across the geographical range of the European wood mouse. Using the method allowing for the best reduction of the informative data set, a comparison of the European wood mouse with the two Asiatic species was performed. Results Within the European wood mouse A. sylvaticus, a strong latitudinal gradient in mandible shape overrides the influence of insularity and genetic structure. Yet, random morphological divergence in insular conditions can be identified as a secondary process of shape differentiation. Size displays no obvious pattern of variation, neither with insularity or latitude. A comparison with two other species of wood mice suggests that a similar latitudinal gradient in mandible shape exists in different species, mandibles being flatter in the north and wider in the south. Main conclusion The latitudinal gradient in mandible shape observed in the three species of wood mice is interpreted as an intraspecific adaptive response to gradual changes in feeding behaviour.     

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.     

Decomposition of Japanese beech wood by diverse fungi isolated from a cool temperate deciduous forest

We assessed 62 fungal strains in 31 species of wood decay fungi in the ability to decompose wood blocks of Japanese beech (Fagus crenata) under a pure culture condition. Fungi were collected in a cool temperate beech forest in Japan and isolated from the inside of beech logs and from sporocarps fruiting on logs and snags of beech that were different in diameter and decay class. Fungi in Holobasidiomycetidae showed marked decomposition of lignin and carbohydrate. These fungi were divided into three groups according to the pattern of lignin and carbohydrate utilization. Phanerochaete filamentosa decomposed lignin selectively. Lampteromyces japonicus, Steccherinum rhois, Trichaptum biforme, Stereum ostrea, Mycena haematopoda, Antrodiella albocinnamomea, Daedalea dickinsii, Daedaleopsis tricolor, Ganoderma tsunodae, and Trametes versicolor decomposed lignin and carbohydrates simultaneously. Psathyrella candolleana, Lenzites betulinus, and Trametes hirsuta decomposed carbohydrates selectively. Species in the Phragmobasidiomycetidae and in the Ascomycota caused low mass loss of wood.     

Predator-avoidance behavior in anuran tadpoles: a new bioassay for characterization of water-soluble cues

Most surveys of large wood in streams are conducted by counting and measuring every piece of large wood within a reach, a technique that is effective but time-consuming. In this study we evaluated an alternative method that takes less time and can be employed in studies in which an estimate of total large wood volume along a stream reach is the primary metric of interest. In first- through third-order streams we estimated in-stream large wood volume and large wood frequency, comparing large wood census estimates to those from a modified a line-intercept technique that has been commonly used in terrestrial forest surveys. Estimates of large wood volume from line transects located in the geographic center of the stream (parallel to stream axis and equidistant from bankfull margins) were highly correlated with those from the wood census (P < 0.001, r ² = 0.88, Pearson’s r = 0.935), but produced slightly greater estimates of large wood volume (regression slope = 1.28, SE = 0.16). Line-intercept estimates of large wood frequency (number per 100 m of stream) were significantly correlated to the wood census counts, but the line-intercept method underestimated frequency by about 50% (P = 0.016). Differences in the estimated large wood volume between line-intercept and wood census surveys were associated with variability in the diameter of the large wood, but unrelated to stream bankfull width, for the range of stream sizes evaluated in this study (≈ 2 to 11 m). Our results suggest that in small constrained streams, line-intercept surveys are an effective method for estimating in-stream large wood volume and that these estimates better approximate results from whole-stream census techniques where the diameter of in-stream wood is relatively consistent. Handling editor: K. Martens     

ANATOMY OF A LIGNITIZED WOOD FROM SENFTENBERG

A piece of lignitized wood from the Miocene of Senftenberg, Germany, was identified as a type of compression wood, and was studied anatomically, as groundwork, in an investigation on cell wall cellulose and lignin. The wood showed affinity to modern Cryptomeria and Taxodium. In each growth ring the early wood was compacted. By contrast, cellular structure in the late wood had been retained to a high degree. Massive compaction of the early wood most likely occurred during the initial stages of sedimentation prior to mineralization. Numerous cell wall deformations in late wood tracheids apparently originated from compressive forces applied to the wood during sedimentation.     

Ultra-structural organisation of cell wall polymers in normal and tension wood of aspen revealed by polarisation FTIR microspectroscopy

Polarisation Fourier transform infra-red (FTIR) microspectroscopy was used to characterize the organisation and orientation of wood polymers in normal wood and tension wood from hybrid aspen (Populus tremula × Populus tremuloides). It is shown that both xylan and lignin in normal wood are highly oriented in the fibre wall. Their orientation is parallel with the cellulose microfibrils and hence in the direction of the fibre axis. In tension wood a similar orientation of lignin was found. However, in tension wood absorption peaks normally assigned to xylan exhibited a 90° change in the orientation dependence of the vibrations as compared with normal wood. The molecular origin of these vibrations are not known, but they are abundant enough to mask the orientation dependence of the xylan signal from the S₂ layer in tension wood and could possibly come from other pentose sugars present in, or associated with, the gelatinous layer of tension wood fibres.     

<Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> as a model for gelatinous fiber formation

Trees and herbaceous plants continuously monitor their position to maintain vertical stem growth and regulate branch orientation. When orientation is altered from the vertical, they form a special type of wood called reaction wood that differs chemically and structurally from normal wood and forces reorientation of the organ or whole plant. The reaction wood of dicotyledons is called tension wood and is characterized by nonlignified gelatinous fibers. The altered chemical and mechanical properties of tension wood reduce wood quality and represent a major problem for the timber and pulping industries. Repeated clipping of the emerging inflorescence stems of Arabidopsis thaliana augments wood formation in organs, including those inflorescence stems that are allowed to develop later. Gravistimulation of such inflorescence stems induces tension wood formation, allowing the use of A. thaliana for a molecular and genetic analysis of the mechanisms of tension wood formation.     

Osservazioni sulla microflora fungina di ceppaie di abete bianco

Abstract

Mycoflora of Silver fir (Abies alba Mill.) stumps. - This work is a first contribution to the knowledge of the mycoflora colonizing Silver fir (Abies alba Mill.) stumps in Italy.

Autochthonous fungal species were isolated from the wood of A. alba stumps from three different sites in the Tuscan Apennines.

Frequency values for the isolated species and taxonomic groups were calculated.

Deuteromycetes (57–82.5%) occurred more frequently than basidiomycetes (5–36%), phycomycetes (0.7–11.6%) and ascomycetes (0–1%). The most common genera were found to be: Aleurodiscus, Penicillium, Phellinus, Phialophora, Scytalidium, Sistotrema and Trichoderma.

An effective method of isolation from wood is also described.     

Wood stimulates the demethoxylation of [O14CH3]-labeled lignin model compounds by the white-rot fungi Phanerochaete chrysosporium and Phlebia radiata

Mineralization of polymeric wood lignin and its substructures is a result of complex reactions involving oxidizing and reducing enzymes and radicals. The degradation of methoxyl groups is an essential part of this process. The presence of wood greatly stimulates the demethoxylation of a non-phenolic lignin model compound (a [O¹⁴CH₃]-labeled β-O-4 dimer) by the lignin-degrading white-rot fungi Phlebia radiata and Phanerochaete chrysosporium. When grown on wood, both fungi produced up to 47 and 40% ¹⁴CO₂ of the applied ¹⁴C activity, respectively, under air and oxygen in 8 weeks. Without wood, the demethoxylation of the dimer by both fungi was lower, varying between 0.5 and 35%. Addition of nutrient nitrogen together with glucose decreased demethoxylation when the fungi were grown on spruce wood under air. Because the evolution of ¹⁴CO₂ in the absence of wood was poor, the fungi may have preferably used wood as a carbon and nitrogen source. The amount of fungal mycelium, as determined by the ergosterol assay, did not show connection to demethoxylation. P. radiata also showed a high demethoxylation of [O¹⁴CH₃]-labeled vanillic acid in the presence of birch wood. The degradation of lignin and lignin-related substances should be studied in the presence of wood, the natural substrate for white-rot fungi.     

An unusual form of reaction wood in Koromiko [<Emphasis Type="Italic">Hebe salicifolia</Emphasis> G. Forst. (Pennell)], a southern hemisphere angiosperm

Koromiko [Hebe salicifolia G. Forst. (Pennell)] is a woody angiosperm native to New Zealand and Chile. Hebe spp. belong to the otherwise herbaceous family Plantaginaceae in the order Lamiales. Reaction wood exerting expansional forces was found on the lower side of leaning H. salicifolia stems. Such reaction wood is atypical for angiosperms, which commonly form contracting reaction wood on the upper side of leaning stems. Reaction wood typical for angiosperms is formed by species in other families in the order Lamiales. This suggests that the form of reaction wood is specific to the family level. Functionally the reaction wood of H. salicifolia is similar to that found in gymnosperms, which both act by pushing. However, their chemical, anatomical and physical characteristics are different. Typical features of reaction wood present in gymnosperms such as high density, thick-walled rounded cells and the presence of (1 → 4)-β-galactan in the secondary cell wall layer are absent in H. salicifolia reaction wood. Reaction wood of H. salicifolia varies from normal wood in having a higher microfibril angle, which is likely to determine the direction of generated maturation stresses.     

Fossil wood of Euphorbiaceae from the Tertiary of West Bengal,India

The paper describes a new species of fossil wood of Euphorbiaceae, Mallotoxylon cleidionoides sp. nov. from the Tertiary Laterites near Santiniketan, Birbhum District of West Bengal. The structure of the fossil wood closely resembles the wood anatomy of the extant genus Mallotus Lour. This is the first record of the occurrence of an euphorbiaceous wood from the Tertiary of West Bengal.