Fractionation of Forest Residues of Douglas-fir for Fermentable Sugar Production by SPORL Pretreatment

Douglas-fir (Pseudotsuga menziesii) forest residues were physically fractionated through sieving. The bark and wood were separated for large-sized fractions (>12.7?mm), and their contents were determined. The chemical compositions of the large fractions were calculated based on the contents and chemical compositions of the bark and wood. The chemical compositions of the fine fractions were analyzed. The bark and wood content in the fine fractions was calculated based on the measured glucan and lignin contents in each fraction. It was found that fractionation by particle/chip size can effectively fractionate bark and wood and therefore lignin from carbohydrates. The large-sized fractions (>12.7?mm) represent approximately 60?% of the collected forest residues but only contain approximately 37?% of the total bark and 35?% of the total ash, or a selectivity over bark and ash of 1.6 and 1.7, respectively. Pretreatment of forest residues by sulfite pretreatment to overcome recalcitrance of lignocelluloses and subsequent enzymatic hydrolysis revealed the presence of 14.3?% bark can reduce substrate enzymatic digestibilities (SED) 16?% compared with that from a bark-free sample. The SED of a bark is 41?% compared with 73?% for wood when pretreated under the same conditions. Separating pretreatment of bark from wood is beneficial for producing a more enzymatically digestible substrate. The results from the present study could have significant implications for harvesting forest residues.     

Trophic relationships and main trends in morphological adaptations of larval mouthparts in sciaroid dipterans (Diptera,Sciaroidea)

The morphological structure of mouthparts and trophic relationships have been studied in the larvae of sciaroid dipterans developing in decaying wood and fruiting bodies (carpophores and basidiomes) of various fungi. Six structural types of mandibles are distinguished, and their specific features are analyzed in relation to the larval mode of life and type of feeding. It is shown that predation is not common in this group. The majority of epibiontic larvae have mandibles that operate like a scraper, collecting various small particles from the substrate surface, which accounts for a mixed type of feeding in these larvae. Original Russian Text ? N.P. Krivosheina, A.I. Zaitzev, 2008, published in Izvestiya Akademii Nauk, Seriya Biologicheskaya, 2008, No. 6, pp. 703–712.     

Effects of flooding on wood and bark anatomy of four species in a mangrove forest community

Variation in the wood and bark anatomy of the dominant species of a mangrove forest community in Mexico was evaluated in relation to some environmental factors, and their physiological adaptations to salinity and flooding period are discussed. The forest is characterized by three zones according to the presence of dominant tree species and flooding periodicity. Vessel arrangement and wood and bark ray height are strongly associated with flooding zones where trees are growing. Variance analyses revealed significant differences among zones for these anatomical characteristics. Soil texture and water salinity were the most useful parameters for the prediction of values of anatomical characteristics. More abundant vessels in radial multiples in a shorter flooding period suggest a functional advantage of multiple vessel groups. Taller wood and bark rays in response to prolonged flooding period can be attributed to anoxic conditions. Among zones, significant differences in the vulnerability index of the species were detected, but not with respect to relative conductivity. Significant differences among zones exist for wood and bark characteristics involved in vertical and horizontal water transport, photosynthates and gas exchange.     

Biomechanical properties of the trunk of the devil's walking stick (Aralia spinosa; Araliaceae) during the crown-building phase: implications for tree architecture

During the crown-building phase, the mechanical architecture of the trunk of Aralia spinosa exhibits considerable ontogenetic variation. All trunks were tapered along their length, and taper was dependent on both ramet size and age; older, larger trunks were more tapered than younger, smaller trunks. Trunk specific gravity, % bark, wood, and pith exhibited considerable inter- and intra-ramet variation. Specific gravity increased with both increasing ramet size and age, and declined acropetally in the majority of ramets sampled. Wood specific gravity was generally unrelated to ramet size, age, or position along the length of the trunk. Percent wood increased while % pith decreased with increasing ramet size and age. There was no relationship between % bark and either ramet size or age. Both % bark and % wood tended to decline acropetally, while % pith increased acropetally. On average, 47% of the variation in specific gravity could be attributed to % wood, while 77% could be attributed to % pith. Percent bark accounted for only 14% of the variation in specific gravity. We suggest that the relatively pithy trunk of Aralia spinosa (average range: 4-15%) allows for rapid height growth, but imposes severe constraints on crown architecture and the maximum size attainable by this species.     

Diaspore bank of bryophytes in tropical rain forests: the importance of breeding system,phylum and microhabitat

Diaspore banks are crucial for the maintenance and resilience of plant communities, but diaspore banks of bryophytes remain poorly known, especially from tropical ecosystems. This is the first study to focus on the role of diaspore banks of bryophytes in tropical rain forests. Our aim was to test whether microhabitat (substrate type) and species traits (breeding system, phylum) are important in explaining the diaspore bank composition. Using samples cultivated in the laboratory, we assessed the number of species and shoots emerging from bark, decaying wood and soil from two sites of the Atlantic rain forest (montane and sea level) in Brazil by comparing the contribution of species by phylum (mosses, liverworts) and breeding system (monoicous, dioicous). More species emerged from bark (68) and decaying wood (55) than from soil (22). Similar numbers of species were found at both sites. Mosses were more numerous in terms of number of species and shoots, and monoicous species dominated over dioicous species. Substrate pH had only weak effects on shoot emergence. Species commonly producing sporophytes and gemmae had a high contribution to the diaspore banks. These superficial diaspore banks represented the extant vegetation rather well, but held more monoicous species (probably short-lived species) compared to dioicous ones. We propose that diaspore bank dynamics are driven by species traits and microhabitat characteristics, and that short-term diaspore banks of bryophytes in tropical rain forests contribute to fast (re)establishment of species after disturbances and during succession, particularly dioicous mosses investing in asexual reproduction and monoicous mosses investing in sexual reproduction.     

Pattern of Substrate Preferences of Free Living Protists (Myxomycetes) on Decaying Wood

We have studied the influence of the stage of decomposition and acidity of wood, as well as the illumination of the microhabitat on the species composition, abundance, and occurrence of slime molds (Myxomycetes) of the xylobiontic (inhabitants of the wood) substrate complex of forest communities in Siberia (Altai krai, Altai Republic, and Novosibirsk oblast). This work is based on a study of 1777 samples of fruit bodies (sporophores) of myxomycetes. In the analysis of data for communities of Myxomycetes of the xylobiontic substrate complex, we recognize a successional series which clearly correlates with the stage of wood decomposition. The study of the distribution of the species composition of the slime mold on wood of various stages of decomposition shows that the maximum number of species is observed on dead trunks where the wood is of medium density and the bark can easily be separated (W3). The lowest specificity and diversity of species composition is observed on the fallen trunks of trees with very dense wood and dense bark (W1). These dead trees have low water-retaining capacity, tight bark, and almost intact wood containing large amounts of lignin, preventing the invasion of plasmodia and myxamoebae of Myxomycetes into the trunk. A study of the location of slime-mold colonies in relation to the illumination level shows that the greatest number of species is found on the front, side, and bottom parts of dead trunks of woody plants. The least specificity and the least variety of Myxomycetes species are found on apical parts of dead tree trunks facing the sun. The exception are species with large fruit bodies such as Fuligo septica and Reticularia splendens, which are most often observed on the upper parts of the sun facing trunks of woody plants. In the research area, the complex of species typical for wood of coniferous trees is described. It is noted that acidophilic slime molds of the genera Comatricha and Cribraria can be traced in xylobiontic and epiphytic–corticuloid substrate complexes.     

Wound reaction after bark harvesting: microscopic and macroscopic phenomena in ten medicinal tree species (Benin)

In Africa, little is known about how the vascular anatomy of medicinal tree species is influenced by bark harvesting, and the ability of species to react against debarking needs to be better understood. This study aims to evaluate the temporal and spatial impact of bark harvesting on wood anatomy and to determine the extent to which a tree’s ability to close the wound after bark harvesting is affected by anatomical changes in the wood. We harvested bark from ten medicinal tree species located in an Isoberlinia doka woodland in Central Benin. Two years after debarking, the wound closure was measured and one tree per species was cut at the wound level to collect a stem disc. On the cross section of each disc, vessel features (area, density and specific conductive area) were measured in the radial direction (before and after wounding) and on three locations around the disc surface. We found that during early wound healing, all species produced vessels with a smaller area than in unaffected wood and this significantly decreased the specific conductive area in eight of the investigated species. However, after 2 years, only six trees had restored their specific conductive area. In addition, a significant positive correlation (r = 0.64, P < 0.005) confirmed the relationship between the specific conductive area and tissue production to close the wound and delineated the study group into two groups of trees. Therefore, we concluded that vessels appeared to be very good anatomical indicators of the tree’s reactions to debarking.     

Lichens on dead wood: species‐substrate relationships in the epiphytic lichen floras of the Pacific Northwest and Fennoscandia

Dead wood is an important habitat feature for lichens in forest ecosystems, but little is known about how many and which lichens are dependent on dead wood. We reviewed substrate use by epiphytic lichens in the combined floras of Fennoscandia and the Pacific Northwest of North America based on literature and herbarium data and analyzed substrate affinity relative to life form, reproductive mode and major phylogenetic group within the floras. A total of 550 (43%) of the 1271 epiphytic species in the combined floras use wood, and 132 species (10%) are obligately associated with dead wood in one or both regions. Obligate and facultative wood‐dwelling guilds in the two floras were strongly similar in terms of internal guild structure in each region, but differ somewhat in species composition, while the bark‐dwelling guild differs strongly in both. Most obligate dead wood users are sexually reproducing crustose lichens. The largest numbers of species are associated with forest structural features such as logs and snags that have been greatly reduced by forest practices. Conservation of lichens inhabiting wood requires greater attention to crustose lichen species and the development of conservation strategies that look beyond numbers and volumes of dead wood and consider biologically meaningful dead wood structure types.     

The influence of cambial age on breeding for wood properties in Picea glauca

We investigated the influence of cambial age on correlations between different wood traits and the possibility of early selection in order to help decision-making for the improvement of juvenile wood in white spruce (Picea glauca (Moench) Voss). Increment cores were analysed from 375 trees covering 25 open-pollinated families from a 30-year-old provenance–progeny trial in Quebec, Canada. Genetic and phenotypic correlations between different mechanical and fibre anatomy-related wood traits were found to vary with cambial age. Most correlations became stronger in magnitude in rings closer to the bark. An exception is the correlation between microfibril angle (MFA) and the modulus of elasticity where correlations were strongly negative from the pith to the bark. Age–age correlations for different wood traits were found to be high and possible gains from early selection were estimated to be good in ring 8 and older for most traits. MFA was the trait with the strongest potential for selection as early as ring 4, but a detrimental correlation with wood density may represent a drawback of such a juvenile selection approach. Estimates showed that selection concentrated on a few easily measurable traits such as wood density and core length holds promise to obtain superior genetic gains for mechanical properties, but negative impacts would be expected on fibre anatomy traits related to pulp quality. These findings show the need for more carefully planned breeding and selection strategies if one wishes to improve several traits for different end uses.     

Macroinvertebrates of flooded trees in the man-made Volta Lake (Ghana) with special reference to the burrowing Mayfly Povilla adusta Navas

Summary The species composition of periphytic macroinvertebrates on and in flooded trees differs at different localities on the Volta Lake. The main differences concern chironomid and trichopteran larvae. The reasons for this lie in the different exposure of trees to wave action, in the availability of soft wood and bark as a substrate, and in the distance of trees off-shore. All these factors determine the intensity of growth of the periphytic algae. The growth of the periphytic fauna will also be influenced by the density of phytoplankton on which it feeds. Other factors, such as oxygen concentration and the turbidity of the water, are also likely to affect the productivity of the whole community.The abundance of Povilla nymphs, the most common organism in trees, seems to depend on the type of the substrate. The bark of trees is exploited more than the wood, and trees with harder wood are less attacked than those with soft wood. Macroscopically, the male nymphs can be distinguished from female nymphs from a length of 6.0 mm, and they start to emerge when 9.0 mm long. Females emerge from 14.0 mm length. Nymphs tend to be heavier in dense populations. The difference in the weight of nymphs may be due to differences in availability of food.Nymphs of Povilla were found to feed both on solitary and attached periphytic algae, together with detritus and planktonic algae. Because of the great abundance of Povilla the nymphs of this species are of great importance in the conversion of algae into animal protein, being themselves heavily exploited by fish.No lunar periodicity, such as occurs on Lake Victoria, was found, and Povilla in the Volta Lake seems to emerge continuously.     

The mechanical role of bark

The ability of stem bark to resist bending forces was examined by testing in bending segments of Acer saccharum, Fraxinus americana, and Quercus robur branches with and without their bark. For each species, the bark contributed significantly to the ability of stem segments differing in age to resist bending forces, but its contribution was age-dependent and differed among the three species. The importance of the mechanical role of the bark decreased basipetally with increasing age of F. americana and Q. robur stem segments and was superceded by that of the wood for segments ≥ 6 yr old. A. saccharum bark was as mechanically important as the wood for stem segments 7 yr old but was not a significant stiffening agent for younger or older portions of stems. On average, the stiffness of the bark from all three species was 50% that of the wood. However, the geometric contribution to the flexural rigidity of stems made by the bark (i.e., the bark's second moment of area) was sufficiently large to offset its lower stiffness (Young's modulus) relative to that of the wood. A simple model is presented that shows that the bark must be as mechanically important as the wood when its radial thickness equals 32% that of the wood and its stiffness is 50% that of the wood. Based on this model, which is shown to comply with the data from three species purported to have stiff woods, it is evident that the role of the bark cannot be neglected when considering the mechanical behavior of juvenile woody stems subjected to externally applied bending forces.     

Phylogeny of a Macaronesian radiation: host-plant use and possible cryptic speciation in Liparthrum bark beetles

The Macaronesian islands are well known for their unique endemic floras of woody plants. Many of these unusual plant groups provide important novel resources for bark and wood boring beetles which breed in dead or moribund parts of their host plants. The bark beetle genus Liparthrum exploits a wide range of unusual host plants and has its highest proportion of species living on the Macaronesian Islands. We used DNA sequences of the mitochondrial Cytochrome Oxidase I gene and the nuclear Elongation Factor 1 alpha gene, and morphological characters, to estimate the phylogenetic relationships among species endemic to these archipelagos, and to trace the evolution of host-plant use. All parsimony and Bayesian analyses of the combined data, and maximum likelihood analyses of the molecular data, showed that species associated with Euphorbia are monophyletic. We also found genetic and subtle morphological evidence for three cases of cryptic speciation in one polyphyletic species associated with different Euphorbia plants, showing that high levels of host specialisation can occur also in insects breeding in older and very dry, dead plant tissues.     

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.     

Modelling Woody Plant Tissues5

An electrical impedance spectrum (20 Hz to 1 MHz) was measuredin both the bark and wood of current-year and one-year-old Scotspine (Pinus sylvestris L.) shoots. The measured impedance spectrawere analysed in reference to two lumped circuits and a distributedcircuit. It was found that neither of the two lumped circuitsfit the data from bark or wood as well as the distributed model.The lumped (double-shell) model fit fairly well for bark, butpoorly for wood. It is proposed that the good fit of the distributedmodel and the poorer fit of the lumped models are due to a widerange of cell sizes in the bark and wood. The distributed circuitused in the present study may be useful for describing differentiatedplant tissues for physiological studies. Key words: Bark, electrical impedance, equivalent circuit, Pinus sylvestris L., wood     

Cryptogam communities on fallen logs in the Duke Forest,North Carolina

Abstract. I studied cryptogam (i.e. bryophyte and lichen) communities on fallen logs in the Duke Forest, Durham and Orange Counties, North Carolina, USA, to determine the relationship of log characteristics and microsite to community composition. Species composition and abundance were estimated for 111 randomly selected fallen logs. Interior wood samples were used to identify the tree species. I determined physical and chemical characteristics for each log, and described the log microsite. Canonical Correspondence Analysis (CCA) detected a clear gradient in cryptogam species composition which is correlated with the species of log and the presence of bark. Communities on hardwood bark, hardwood wood, and pine substrates were the most distinct. CCA also revealed that the microsite is not as closely related to species composition as are substrate pH and density. The majority of the cryptogam species encountered on the fallen logs are commonly reported from other substrates in the forest. However, within the habitat type of fallen logs, several species were apparently restricted to certain substrate types.     

The conservation requirements of an endangered hoverfly, Hammerschmidtia ferruginea (Diptera, Syrphidae) in the British Isles

The saprophagous larva of the endangered hoverfly, Hammerschmidtia ferruginea (Fallén, 1817) (Diptera, Syrphidae) develops in wet, decaying sap under the bark of dead trees and branches of aspen, Populus tremula L. (Saliaceae). However this breeding site is transient: wet decay builds up patchily over 1.5–2 years of the tree or branch dying and lasts for a further 1–3 years before the bark falls off. Between 1990 and 2006, H. ferruginea swung through a cycle of abundance when the number of localities where it was detected dropped from 13 to 5 and back to 8. Fluctuations in amounts of dead wood caused by winds and storms probably explain this population swing. When there are few dead trees and branches, H. ferruginea breeds in sap flows on live P. tremula trees and populations are maintained but at low levels. To prevent local extinctions during periods when fallen wood is scarce, breeding habitat can be supplemented by felling trees and branches. Fallen wood with wet decaying sap is also important as an assembly site for mate selection. Adult food plants include flowers of bird cherry Prunus padus, rowan Sorbus aucuparia and hawthorn Crategus monogyna. Adults were recorded dispersing up to 1 km but are probably able to move further than this.     

Improving wood quality in the western gulf forest tree improvement program: the problem of multiple breeding objectives

Currently, both industrial and private landowners in the Western Gulf Forest Tree Improvement Program (WGFTIP) area are compensated for their timber primarily based on the weight or volume of green wood reaching the mill gate. This places an immediate economic focus on adaptability and volume growth. However, selection for volume growth alone could result in decreased wood quality over time. Wood quality characteristics including stem straightness, wood specific gravity, and microfibril angle have either neutral or slightly unfavorable genetic correlations with volume growth in the WGFTIP loblolly pine (Pinus taeda L.) program. Since most WGFTIP members also consider wood quality an important selection criterion, the WGFTIP must define the best possible set of selection criteria given that (1) no single set of breeding objectives can be considered optimal for multiple products and (2) improvement in wood quality has no readily recognized economic importance in the existing market. To meet this challenge, the WGFTIP has implemented different strategies for its mainline breeding and deployment populations. In the mainline population, consistent breeding and selection criteria are used across members, while in the various deployment populations, selections are tailored to meet the specific needs of each member. The WGFTIP is also developing an elite wood quality population (WQEPop) based on backward selection. For the WQEPop to be successful, the economic importance of improved wood quality must be recognized, and landowners must be compensated for growing higher quality timber, especially if this results in reduced volume production. Improved methodology for within-family selection and for wood quality trait measurement is also important.     

Changes in nitrogen levels and free amino acids in rooting cuttings of mulberry (Moms alba)

Total and protein nitrogen in bark and wood of parent stems of mulberry ( Morns alba L. cv. Ichinose) decreased readily and to the same extent during leafing-out of the buds, but the decrease in wood was less marked than in bark. Simultaneously, soluble nitrogen in both bark and wood also declined but the depletion was less marked than that of total and protein nitrogen. During the same period total nitrogen in the new shoots and adventitious roots increased drastically; however, the increase in total nitrogen in the growing parts during rooting was almost the same as the decrease in total nitrogen in the parent stems. Proline, the prevalent amino acid in wood and bark of the parent stems, decreased drastically during rooting, whereas during the same period asparagine in the developing buds, callus and adventitious roots increased markedly and became the predominant amino acid. The amount of arginine was relatively high in bark of the parent stems but Low in wood and the buds. The level of arginine in bark decreased considerably during the experiments (as did that of proline). The results suggest that the nitrogen required by the growing parts (sinks) in the rooting cuttings comes mainly from protein breakdown in bark of the parent stems (source), although stored protein in wood (source) and soluble nitrogen in bark and wood (sources) also play a part in storage of nitrogen. Asparagine is suggested to be the main nitrogen transport compound in the new growth of the tree and the initiating roots of cuttings.     

A review of biomass quality research relevant to the use of poplar and willow for energy conversion

It has been recognized that the chemical and physical properties of biomass feedstocks can play an important role in the efficiency of most energy conversion processes. These properties include the ratio of bark to wood, moisture content, specific gravity, calorific or heating value, and the relative content of extractives, α-cellulose, hemicellulose, and lignin.A review of the literature dealing with the quality of poplar and willow biomass feedstock for energy conversion revealed that considerable variation existed in many of these traits. This variation may make it possible to improve the quality of feedstock through breeding and selection.Little information exists with respect to heritability (both in the broad sense and narrow sense), the genetic correlation between characters, and the presence of genotype-environment interaction. A better understanding of these parameters is essential if the apparent variability is to be used to improve biomass quality.     

Wood and bark anatomy of Hypocalyptus support its isolated taxonomic position in Leguminosae

The wood and bark anatomy of all three species of Hypocalyptus from the monotypic South African endemic tribe Hypocalypteae were studied. Despite large morphological differences (especially in habit) the species were found to be similar in wood and bark structure. Discontinuities are quantitative only, relating mainly to differences in growth form between H. oxalidifolius, a short-lived shrublet, and the two other species, H. coluteoides and H. sophoroides, both of which are erect shrubs or small trees of up to 6 m tall. Hypocalyptus wood has a mesomorphic structure with vessels solitary or in small groups, reflecting relatively moist habitats in fynbos vegetation. In contrast to many genera of Leguminosae for which data are available, crystals are absent from the wood. This is the first report of tanniniferous tubes in the wood of Leguminosae (previously reported only in Myristicaceae and a genus from Ulmaceae). The presence of tanniniferous tubes and the absence of crystals in all three species of Hypocalyptus underline the isolated position of the genus and support its tribal status.