Recent Wood Research Articles

Synthesis of hydroxylated oligoamides for their use in wood conservation

AbstractSome oligo‐ or polyamides containing several hydroxyl groups were synthesized in order to obtain new water‐soluble compounds with a high affinity for polar materials as wood, paper, and natural fibers. The interest for the synthetic procedures is the use of renewable sources as starting compounds. In fact natural compounds or their derivatives, as l‐tartaric acid, d(+)‐glucaric acid and α,α‐trehaluronic acid, were used as dicarboxylic acids in the polycondensation reactions, in order to obtain several functionalized oligoamides. All the compounds obtained in this study were characterized through FTIR and NMR spectroscopy. The oligoamides, water‐soluble and not provided with high‐molecular weights, were tested as wood consolidants. Physical properties like hygroscopicity of stabilized wood, volume shrinkage, density, and basic density were evaluated on the treated samples and compared with those obtained in the same conditions for an untreated archeological sample and a recent wood sample. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Quantifications of dendrochronological information from contrasting microdensitometric measuring circumstances of experimental wood samples

We analyzed how the pretreatment method of Scots pine (Pinus sylvestris L.) wood specimens together with X-ray methodology applied for density analyses affect resulting tree-ring data and derived proxy-based climate information. We also evaluated whether these results from two contrasting laboratory circumstances could be homogenized by applying dendroclimatic statistical methods. For this study, we measured a pair of X-ray based microdensitometry datasets using double samples of subfossil and recent wood specimens. Dendrochronological information of earlywood and latewood series was examined to determine for alterations in the resulting data. We found that the level of overall density, its trend over cambial ages and the growth amplitude altered due to the sample pretreatment/density measuring exercise, which means that comparisons of heterogeneous datasets should be, in general, regarded cautiously. Dendrochronological standardization did, however, even out several potentially biasing influences from the differing overall densities and their trends. The two latewood (maximum) density chronologies yielded paleoclimatic reconstructions which both calibrated and verified satisfactorily with the instrumental warm-season (March–September) mean temperatures. The transfer functions were found to further equalize the differences between the two proxy records. We recommend (if no strictly homogenous data are available) reconciling similar data assemblages through transfer functions with multiple independent variables.

The presence of sulfuric acid in alum-conserved wood – Origin and consequences

Abstract Dealing with the consequences of historical conservation treatments is an issue that conservators and conservation scientists will meet with increasing frequency as conservation materials naturally age and interact with materials the objects are made from. One example is the use of alum salts to treat waterlogged archaeological wooden objects during the 100-year period between 1850–1950. This now-obsolete method was widely used in Scandinavia, but also worldwide. Today many objects treated with alum are damaged and are actively deteriorating. The wood is highly acidic (pH 1-2.5), it is brittle with little remaining structural integrity. It is thought that, in addition to decay processes possibly initiated by absorbed metal ions, the presence of sulfuric acid, generated during treatment, plays a central role in the active deterioration process observed. To understand the alum treatment better, it was applied to recent wood, freshly excavated archaeological wood and pure cellulose paper. It was found that the samples became more acidic after treatment. The same material types were also treated with solutions of sulfuric acid, pH 0-3, to compare the effects of acid of known concentrations. The present contribution discusses the immediate effects of high acidity on these samples, due to the recent treatment by alum salts and by sulfuric acid. The newly treated samples were compared with alum-treated wood from the Oseberg find 100 years ago. It also includes preliminary investigations on the behaviour of alum salt during heating, in the solid state as well as in solution.

Compression Strength of Fir and Beech Wood Modified by Citric Acid

Fir wood (Abies alba Mill.) and beech wood (Fagus sylvatica L.) were impregnated by citric acid (CA) with natrium-dihidrogen-hipofosfit (NaH2PO2) as a catalyst. Part of the impregnated samples together with control samples were cured at the temperature of 140 °C for 10 hours, other part of samples was cured in microwaves for 35 minutes. Average compression strength parallel to the grain of wood modified using different regimes of curing was compared to the strength of the recent wood. Average compression strength parallel to the grain of wood retained after modification. In the case of fir wood average compression strength was even improved after modification. The results indicate that wood modified by citric acid may be considered for the purposes where compression strength properties are equally important as improved durability and dimensional stability of wood.

Aging of wood: Analysis of color changes during natural aging and heat treatment

AbstractThe color properties of aging wood samples from historical buildings have been compared with those of recent wood samples that were heat treated at temperatures ranging from 90°C to 180°C. The results of kinetic analysis obtained by the time-temperature superposition method showed that the color change during natural aging was mainly due to a slow and mild oxidation process. In other words, heat treatment could accelerate the changes in wood color that occur during aging. In one sample, the color change (ΔE*ab) after 921 years at ambient temperature was almost equivalent to that of heating (artificial aging) approximately for 6.7 h at 180°C. The results have been interpreted that the aging and the subsequent change in wood color begin at the time of tree harvesting.

Comments: Positive Forecasts

Editor's column Higher oil prices, continued enthusiasm over shale, and the influx of capital are combining to paint a bright picture for the oil and gas industry this year. Both operators and the service sector appear optimistic for growth opportunities—despite some uncertainty surrounding offshore drilling—as the industry quickly rebounds from recession. The Original E&P Spending Survey by Barclays Capital forecasts that global E&P spending will increase 11% this year, from USD 442 billion in 2010 to USD 490 billion in 2011. The survey is based on information from 402 international oil companies, national oil companies, and independents. The outlook for spending in Latin America, the Middle East and North Africa, and Southeast Asia appears particularly bright. International oil companies will post the largest increases in spending, says the study, a reversal from previous years when national oil companies led spending increases. BP, Chevron, ConocoPhillips, ExxonMobil, Shell, and Total are expected to boost expenditures by 18% in the aggregate. Factors driving the increased spending by operators include engineering and construction spending for several large liquefied natural gas projects, increased spending in Iraq, and an increase in deepwater activity, the report said. A recent Wood Mackenzie analysis reported that global upstream capital spending for 2010 would hit USD 380 billion and that many regions and sectors of the upstream industry are regaining confidence. Spending last year was about USD 19 billion higher than in 2009 but 10% lower than 2008. The Wood Mackenzie report said it expects spending to continue to increase in the short term and recover to 2008 levels by 2012 or 2013. The industry’s recovery is largely being led by spending on developing unconventional resources such as shale, the report said. Although most of the spending to date has been in developing US shale plays, operators are increasingly eyeing opportunities in Eastern Europe and elsewhere. Also boosting recovery is the influx of capital. More than half of chief financial officers (CFOs) in the oil and gas industry report that their companies’ ability to access capital and credit is either the same or better than it was a year ago, according to a study by BDO USA, an accounting and consulting organization. That renewed access to capital is allowing companies to aggressively pursue the acquisition of new properties, technologies, and other companies. In addition, 95% of the CFOs surveyed expect to maintain or increase the number of personnel employed by their companies this year. The oilfield services sector also appears healthy. The annual IHS Herold Review of the Oil Field Services Sector reported that key oil company financial performance for service companies by late last year had greatly improved, including for Baker Hughes, Halliburton, and Schlumberger as well as for offshore drilling contractors Transocean, Diamond Offshore, and Oceaneering International, among others.

Effects of burial of Quercus spp. wood aged 5910 ± 250 BP on sorption and thermodynamic properties

The hygroscopicity and thermodynamic properties of buried Quercus spp. wood aged 5910 ± 250 BP were studied and compared with wood of the same genus from recently felled trees. This was done by calculating the 35 °C and 50 °C sorption isotherms and fitting them in accordance with the GAB model. The thermodynamic parameters were obtained from the isotherms using the integration method of the Clausius–Clapeyron equation. Infrared spectra (FTIR) and X-ray diffractograms, respectively, were used to determine possible chemical modifications and changes in the crystalline structure of the cell wall. The long period of time the wood was buried caused a decrease in the crystallinity index of the cellulose and a subsequent increase of amorphous zones with new areas of access for –OH groups. As a result, the equilibrium moisture contents of the buried wood are higher than in the recent wood, in both adsorption and desorption. In terms of the thermodynamic properties, the heat involved is greater in the buried wood than in the recent wood.

Mechanical characteristics of aged Hinoki wood from Japanese historical buildings

Abstract Wood is present in many cultural heritage objects in Japan thanks to its capacity to resist over a long period of time. However, the evolution of its properties in regular use remains insufficiently known. The present study on the effect of wood aging takes advantage of the Japanese context where building traditions have been maintained for centuries. 3-point bending tests were performed in longitudinal (L) and radial (R) directions on small clear wood specimens cut from 8 historical samples and one modern reference considered of high quality by craftsmen. Although aged wood appeared more rigid and stronger than recent wood, after density and humidity corrections were applied no significant variation of L and R rigidity or L strength was observed. The post-linear behaviour, however, was drastically influenced by wood age especially in R direction where the strength and rupture energy decreased markedly with the time elapsed since the wood was processed. Well preserved aged wood considered as safe as long as it is not loaded perpendicular to grain. To cite this article: M. Yokoyama et al., C. R. Physique 10 (2009).

The impact of former agriculture on habitat conditions and distribution patterns of ancient woodland plant species in recent black alder (Alnus glutinosa (L.) Gaertn.) woods in south-western Poland

Little is known about the influence of former agricultural use of soils on the forest recovery process in post-agricultural black alder (Alnus glutinosa) woods – the most fertile and the wettest forest habitats among the European temperate forest types. Thus, studies focusing on edaphic, hydrological and light conditions responsible for colonization mechanisms present in such woodlands adjoining ancient ones were undertaken in south-western Poland. In the 16m2 quadrats of the 33 transects laid out perpendicularly across the ancient-recent forest boundary, data were collected on herb layer composition, chemical soil properties, as well as illumination level. Additionally, groundwater level in the spring months was recorded in piezometers. The number and cover of true woodland herbs were higher in ancient woods, regardless of forest type. Soils in ancient woodlands reached higher levels of Al3+, K+, cation exchange capacity (CEC), available K, P, and organic C, whereas their pH was lower. The illumination level of the forest floor was greater in recent woods. Linear regression showed that recent wood age had a negative effect on pH and base cations, but positive on Fe2+, Ca2+, available P and Mg, CEC, and on C and N contents. CCA results showed that woodland age, pH, humus type, groundwater level, available Mg and K were always among those variables having the highest contribution in explaining the distribution pattern of woodland species in recent woods. Total N and available P contents were always higher in ancient woodland soils than in recent, and their content grew with time. Thus, they cannot be treated as indicators of former agricultural use of recent alder wood soils. Urtica dioica, Poa trivialis and Galium aparine, the three competitive herbs, avoided sites with a high level of groundwater, combined with poor illumination level. In order to create the best possible conditions allowing for effective forest recovery in habitats of such high fertility, it is essential to maintain a good water regime and shade in the forest floor. This in turn reduces the competitive exclusion of woodland flora by the aggressive herbs and facilitates the immigration of typical woodland herbs.

Sorption and thermodynamic properties of buried juvenile Pinus sylvestris L. wood aged 1,170 ± 40 BP

The hygroscopicity and thermodynamic properties of buried juvenile Pinus sylvestris L. wood with an age of 1,170 ± 40 BP were compared with the corresponding values of juvenile wood of the same species from recently cut trees. The 35 and 50°C isotherms were plotted following the saturated salts method and subsequently fitted in accordance with the GAB model. The isotherms were then compared by means of the hysteresis coefficients. X-ray diffractograms were used to analyse the crystal structure of the cellulose. The effect of time on the buried wood caused hemicelluloses degradation and a decrease in the crystallinity index and the crystallite length, resulting in an increase in the proportion of amorphous zones. Because of this, the equilibrium moisture contents of the buried wood are higher than of the recent wood, both in adsorption and desorption. In terms of the thermodynamic properties, the heat involved is greater in the buried wood than in the recent wood.

Sorption and thermodynamic properties of juvenile Pinus sylvestris L. wood after 103 years of submersion

Abstract The hygroscopicity and thermodynamic properties of juvenile Pinus sylvestris L. wood taken from the submerged piles of a bridge built in 1903 over the Jiloca River, in Spain, were compared with the corresponding values of juvenile wood of the same species from recently cut trees. The 35°C and 50°C isotherms were plotted and subsequently fitted using the Guggenheim-Anderson-Boer-Dent method, and the isosteric heat of sorption was obtained through the integration method of the Clausius-Clapeyron equation. The isotherms were compared by means of the hysteresis coefficients. Infrared spectra were recorded to study the chemical modifications, and the crystal structure of the cellulose was studied by X-ray diffractograms. The submersion in water resulted in hemicellulose degradation and a decrease in the crystallinity index and the crystallite length, accompanied by a corresponding increase in the proportion of amorphous zones. Owing to this, the equilibrium moisture contents of the water logged wood are higher than in the recent wood, both in adsorption and in desorption. In terms of the thermodynamic properties, the bond energy is higher in the recent wood than in the water logged wood.

Leaf and wood carbon isotope ratios, specific leaf areas and wood growth of Eucalyptus species across a rainfall gradient in Australia

Leaves and samples of recent wood of Eucalyptus species were collected along a rainfall gradient parallel to the coast of Western Australia between Perth in the north and Walpole in the south and along a southwest to northeast transect from Walpole in southwestern Australia, to near Mount Olga in central Australia. The collection included 65 species of Eucalyptus sampled at 73 sites and many of the species were collected at several sites along the rainfall gradient. Specific leaf area (SLA) and isotopic ratio of 13C to 12C (delta 13C) of leaves that grew in 2002, and tree ring growth and delta 13C of individual cell layers of the wood were measured. Rainfall data were obtained from the Australian Bureau of Meteorology for 29 locations that represented one or a few closely located collection sites. Site-averaged data and species-specific values of delta 13C decreased with decreasing annual rainfall between 1200 and 300 mm at a rate of 1.63 per thousand per 1000 mm decrease in rainfall. Responses became variable in the low rainfall region (< 300 mm), with some species showing decreasing delta 13C with rainfall, whereas delta 13C increased or remained constant in other species. The range of delta 13C values in the low rainfall region was as large as the range observed at sites receiving > 300 mm of annual rainfall. Specific leaf area varied between 2 and 6 m2 kg(-1) and tended to increase with decreasing annual rainfall in some species, but not all, whereas delta 13C decreased with SLA. The relationship between delta 13C and SLA was highly species and soil-type specific. Leaf-area-based nitrogen (N) content varied between 2 and almost 6 g m(-2) and decreased with rainfall. Thus, thicker leaves were associated with higher N content and this compensated for the effect of drought on delta 13C. Nitrogen content was also related to soil type and species identity. Based on a linear mixed model, statistical analysis of the whole data set showed that 27% of the variation in delta 13C was associated with changes in SLA, 16% with soil type and only 1% with rainfall. Additionally, 21% was associated with species identity. For a subset of sites with > 300 mm rainfall, 43% of the variation was explained by SLA, 13% by soil type and only 3% by rainfall. The species effect decreased to 9% because there were fewer species in the subset of sites. The small effect of rainfall on delta 13C was further supported by a path analysis that yielded a standardized path coefficient of 0.38 for the effect of rainfall on SLA and -0.50 for the effect of SLA on delta 13C, but an insignificantly low standardized path coefficient of -0.05 for the direct effect of rainfall on delta 13C. Thus, in contrast to our hypothesis that delta 13C decreases with rainfall independent of soil type and species, we detected no statistically significant relationship between rainfall and delta 13C in leaves of trees growing at sites receiving < 300 mm of rainfall annually. Rainfall affected delta 13C indirectly through soil type (a surrogate for water-holding capacity) across the rainfall gradient. Annual tree rings are not clearly visible in evergreen Eucalyptus species, even in the seasonally cool climate of SW Australia. Generally, visible density transitions in the wood are related not to a strict annual cycle but to periods of growth associated mainly with rainfall. The relationship between delta 13C of leaves and the width of these stem increments was not statistically significant. Analysis of stem growth periods showed that delta 13C in wood responded to rainfall events, but carbohydrate storage and reallocation also affected the isotopic signature. Although delta 13C in wood of any one species varied over a range of 2 to 4 per thousand, there was a general relationship between delta 13C of the leaves and the annual range of delta 13C in wood. We conclude that species-specific traits are important in understanding the response of Eucalyptus to rainfall and that the diversity of the genus may reflect its response to the large climatic gradient in Australia and to the large annual and interannual variations in rainfall at any one location.

Effect of proximity to ancient deciduous woodland on restoration of the field layer vegetation in a pine plantation

The influence of dominant tree species, soil conditions and distance from an adjacent ancient oak‐hornbeam woodland upon the floristic composition, species richness and spatial distributions of species in a pine wood planted on dry rendzina soil were studied in southern Poland. It was found that, in spite of a 52‐yr long succession, the cover and composition of species in the pine wood were significantly different from that in the adjacent ancient woodland. Canonical correspondence analysis (CCA) and stepwise regression analyses showed that the distance to the ancient woodland had a significant influence on species distributions in the recent wood. The numbers of species from the Querco‐Fagetea class, vegetatively reproducing species and myrmecochores decreased with this distance, whereas the numbers of tree species in the shrub and field layers and anemochores increased. The light intensity had a positive effect on the numbers of species in the shrub layer, non‐woodland species and anemochores. The number of woodland species increased considerably with the cover of quickly decomposing litter and with thickness of the humus layer. The migration rate of many woodland species, calculated on occurrence of the farthest individuals was very slow, varying from 0.18 m yr−1 to 0.38 m yr−1. These results indicate that the availability of micro‐sites suitable for seed germination and plant development determined the successful colonization of the recent wood to an extent comparable with the seed dispersal.

Wood science in a changing world - Where are we headed?

The 1999 IAWS Academy Lecture examined the field of wood science – past, present, and future. Although the history of wood science has been less than a century in the making, the history of innovation in wood products design and use extends over a much longer time frame. It is a bit humbling to realize that some of the products that are discussed in technical and scientific meetings today had their origin hundreds or even thousands of years ago. Wood science research efforts began as early as the late 1800s, but formal establishment of research and academic institutions did not occur until after the beginning of the 20th century. In the half century that followed 1910, wood science gradually became recognized as a separate and distinct field of science, technological development, and professional pursuit. The wood science and technology profession is currently at a defining moment in history. Despite considerable scientific advancement and new product innovation relative to wood science in recent decades, wood science and technology as a profession and field of academic study is undergoing decline in the United States and several other regions of the world. Professional societies, institutions, and agencies that focus on the science and technology of wood as an industrial material, including the International Academy of Wood Science, will likely need to change to be effective in the future.

Wood Identification -A Review

Wood identification is of value in a variety of contexts - commercial, forensic, archaeological and paleontological. This paper reviews the basics of wood identification, including the problems associated with different types of materials, lists commonly used microscopic and macroscopic features and recent wood anatomical atlases, discusses types ofkeys (synoptic, dichotomous, and multiple entry), and outlines some work on computer-assisted wood identification.

Physico-Chemical Characteristics of Waterlogged Archaeological Wood

Waterlogged wood samples 300 to 100.000 years old of Picea abies, Pinus sylvestris and Quercus sp. from northern Europe (Norway, Sweden) that had been preserved in a glacier, burial grounds, house settlements, harbour installations and sunken ships in the sea were examined for changes in physico-chemical characteristics as compared to recent wood. The results showed that in waterlogged wood of all species the solubility in 1% NaOH (8.39-22.85%) was found to be higher than that of recent wood (3.84-5.57%). Ash content varied between 1.37-7.12% in old wood and was much higher than in fresh wood (0.31-0.65%). Klason ligin in old wood (25.71-72.40%) was higher than in fresh wood (20.31-30.95%) while crystallinity index (12.79-33.69%) was found to be lower than in fresh wood (34.56-40.20%). Increasing lignin content in old wood resulted in reducing the crystallinity index up to 3.1 times.

A deep water patellogastropod from oligocene water-logged wood of Washington State, USA (Acmaeoidea: Pectinodonta).

Late Oligocene concretions from the shores of the Strait of Juan de Fuca, Washington State, USA contain limpets that represent the earliest record of the taxon Pectinodonta. Assignment of these specimens to this taxon is based on scanning electron microscopy of shell microstructure and their intimate association with fossil wood. Shell microstructures in the Pectinodonta consist of an outer calcitic homogeneous/simple prismatic layer followed by a calcitic foliated layer, an aragonitic comarginal crossed lamellar layer, myostracum, and an aragonitic cone complex crossed lamellar layer. A size class analysis of pectinodontids from different pieces of fossil and Recent wood suggests that few cohorts are found on any single piece of wood, and we speculate about possible factors that may produce this pattern. Lastly, we describe Pectinodonta palaeoxylodia Lindberg & Hedegaard new species and associated taxa from this water-logged wood community.

Sources of Radon Contamination in 14C Dating

We investigated the effect of radon (222Rn) contamination of samples and chemicals used for sample preparation and gas purification on the 14C age of samples. Radon count rate was monitored over several 222Rn half-lives in a proportional counter filled with methane. We analyzed ca. 240 samples of fossil and recent wood, charcoal, bone, dissolved inorganic carbon in water, travertine, peat, aquatic plants, organic soil and atmospheric CO2 for 222Rn contamination. Chemicals used for gas purification (MnO2, Mg(ClO4)2), ruthenium-coated pellets used for catalytic reduction of CO2 to CH4, and acids used for dissolution of calcareous samples (HCl and H3PO4) are also potential sources of Rn. Most geological samples contained a significant amount of Rn, as opposed to samples of wood, charcoal, aquatic plants and atmospheric CO2. We also studied Rn contamination of water samples during tritium activity measurements in a CH4-filled gas proportional counter. We found an increased count rate in the 3H channel, as well as above the 20 keV region in Rn-contaminated groundwater samples.

Variations of trace element concentrations in red spruce tree rings

The potential of coniferous trees as biological indicators of heavy metal atmospheric pollution was investigated. In 31 municipalities of an industrialized region, samples of wood from the trunks of red spruce (Picea rubens) were taken to determine the spatial distribution of accumulated metals. Using the annual rings, these core samples were divided into 5-yr sections to determine temporal variations. The concentrations of Mg, Al, Ca, Mn, Fe, Cu, and Zn were measured by neutron activation analysis. All metals showed the highest concentrations in the most recent wood and the bark. For the wood older than 5 yr, Mn and Zn are stable with time, Mg and Ca decrease, while Al, Fe, and Cu appear to increase. A statistical analysis showed the municipalities with the highest variations in metal concentrations; it also revealed correlations in the fluctuations of several of the metals. As expected, trees in towns near metal refineries contain higher amounts of Mn, Fe, and Al. Large variations in metal concentrations, due to factors not totally understood, were observed. Thus, red spruce is not a sensitive bio-indicator of atmospheric metal pollution.

Identification of archaeological and recent wood tar pitches using gas chromatography/mass spectrometry and pattern recognition

An analytical method has been developed for the assignment of recent and archaeological wood tar pitches to the species of trees used for their preparation. It incorporates the prepurification by Kugelrohr distillation and solid-phase extraction followed by gas chromatography/mass spectrometry analysis. Distribution patterns of volatile, thermostable triterpenoids and steroids characterizing the biological origin of the pitches are evaluated vy principal component analysis (PCA) and discriminant component analysis (DCA) of the data.