Udo H. Sauter

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• PhD
• Head of Department retd. at Forest Research Institute Baden-Wuerttemberg

The project aimed to make small-diameter oak logs available as structural timber members, e.g., for columns, frameworks, and agricultural buildings. In this context, we report on the results of stiffness and strength prediction for small-diameter oak logs' strength classification applying similar approaches as known for sawn timber machine strength...

Moisture content (MC) is a major quality characteristic of wood with respect to drying and mechanical properties. However, exact measurement of wood moisture is difficult both in practical environment and for research purposes. The objective of this study was to develop an optimal method for determining the mean MC of small-diameter oak logs to est...

In most European countries, small-diameter oaks are not considered for structural use. The basis for structural use and design are the knowledge of the specific mechanical properties and the understanding of performance influencing factors like wood defects, moisture content and density distribution. Oak logs of Q. petraea (Matt.) Liebl. have been...

In Germany, only half the annual increment is used in oak stands. Especially small-diameter oaks are currently either not used or only used as firewood. To achieve long-term carbon dioxide storage and higher added value, a finished research project aimed to make small-diameter oak logs available as structural timber members, e.g., for columns, fram...

III Congreso Ibero-Latinoamericano MAD de la Madera en la Construcción (CIMAD 24) : Libro de Actas de Resúmenes Extendidos

The green oak building research project deals with small-diameter oak logs as sustainable constructionmaterial for timber truss structures. The basis for structural use and design are the specific mechanical properties and theknowledge of performance influencing factors like wood defects, moisture content and density distribution. In a first step,t...

In Germany, only half of the annual increment of oak stands is used. Especially small-diameter oaks are currently either not used or only used as firewood. This research project aims on making small-diameter oak logs available as structural timber members. For this purpose, the mechanical properties of the logs and factors influencing them must be...

Due to climate change the availability of softwood structural timber will diminish in Germany over the next decades; in contrast hardwood species like oak are said to cope better with the predicted temperatures and precipitation, and such timber will be available in larger quantity. Especially small-diameter oak is currently either not used or only...

Owing to favorable wood properties and its resilience to the effects of climate change, Douglas fir (Pseudotsuga menziesii) is a promising tree species in Central Europe. Its wood and bark extractives could also serve as feedstock for the production of bio-based materials and platform chemicals. In this study, sapwood, heartwood, knotwood and bark...

This introducing chapter explains the importance of forestry as primary wood producer as well as the sources of wood. Starting point is the Sect. 1.1.1, “Global Forest Resources,” which provides basic data and information on global forests and forest area. The main functions of forests and how forests provide various goods and ecosystem services ar...

Forstliche Versuchs-und Forschungsanstalt Baden-Württemberg (FVA) Hochschule Mainz, Forschungsgruppe Holz und Kunststoffe (HSM) Entwicklungsziel ist die bautechnische Verwendung von bisher als problematisch eingestuften Holzsortimenten. Am Beispiel der Eiche wurde exemplarisch untersucht, wie un-oder geringwertig genutztes Laubschwachholz mit mo...

The precise location of forestry machines is of fundamental importance for sustainable, soil-conserving and equally efficient and safe timber utilization. However, with global navigation satellite system (GNSS) receivers available to date, reliable positioning in the sub-meter range and in real time in forest stands is not possible, as the environm...

Branches are not only of vital importance to tree physiology and growth but are also one of the most influential features in wood quality. To improve the availability of data throughout the forest-to-industry production, information on internal quality (e.g. knots) of both felled and standing trees in the forest would be desirable. This study prese...

Branches are as essential for tree growth as knots are detrimental from the wood quality point of view. To bridge the gap between tree growth and the quality toward end-use, this study aims to establish a relationship between internal and external diameters of Douglas-fir whorl branches. The data comprised 102 trees of a wide age range (30–80 years...

In order to compare the vibration and noise exposure of STIHL’s battery-powered MSA 220 C and the combustion driven MS 201 C, a professional operator was monitored during a pre-commercial thinning operation in a twenty-year-old hardwood stand. The vibration levels were measured with a tri-axial accelerometer on the front and rear handle of both the...

Timber utilisation and wood construction are fundamental components of Europe's strategy on progressing towards a sustainable bio-based economy. Both components require optimised strength grading procedures in Europe's sawmills. To further improve the current procedures, quality assessment and segregation of the raw material need to start already a...

In the field of electronic roundwood measurement, 3D-laser systems are becoming more and more important for the determination of log volume and quality. Especially the outer shape of the logs is of particular importance for the yield and should therefore be described in as much detail as possible. This study focuses on the parameter curvature and c...

Die Holzernte und -rückung mit Seilkrananlagen bietet im Hinblick auf die Bodenpfleglichkeit von Holzerntesystemen einige Vorteile. So ist die seilgestützte Holzrückung nicht nur in Hanglagen, sondern auch zum Schutz ebener Lagen von Bedeutung. Auch kann sie hinsichtlich des Verfahrens variieren, beispielsweise je nach Stärkeklasse des ausscheidend...

Cable-based timber extraction offers some advantages with regard to impacts to forest stands and soils, and can be used under a wide range of conditions. It is important not only in steep terrain, but also increasingly in flat terrain when soils have low bearing capacity. In this study, utilization data from two commonly used tower yarding systems...

For decades, researchers have been working on methods to enable machine strength grading beginning at the round timber stage, instead of doing the grading only on the sawn timber. This would lead to an integrated process, by which raw material efficiency and product quality of construction timber production could be optimized throughout. The newest...

Teak (Tectona grandis) is a high-value hardwood species often used in furniture and shipbuilding because of its durability and elegance in appearance. The natural oil and rubber content of teak wood protects it from wood decomposition making it also suitable for outdoor use. Sapwood on the outer layer of the tree trunk has a bright color but has lo...

Whorl knots play an important role on growth models, as they typically delimit annual shoots. They are on average larger than internodes, and usually have a higher impact on wood quality grading. In this context, an automatic classification of knots into whorls is primordial to connect internal and external tree attributes using computed tomography...

Key message A fully automated algorithm allowed knot detection and positioning on computed tomography (CT) images of Douglas-fir logs. The detection of knot diameter and status could benefit from further improvements, i.e., testing other configurations and implementing texture measures. Manual measurement on CT images allows for tridimensional asse...

Interest in utilization of hardwoods for glued structural timber products like glued laminated timber and cross-laminated timber is increasing due to external factors such as shifting availability of softwoods and hardwoods and rising demand for timber in the building sector and favourable mechanical properties of hardwoods. In an orienting study,...

Die in Nordamerika beheimatete Douglasie bildet sehr hochwertiges Kernholz, das vielseitig eingesetzt werden kann. Insbesondere für den Einsatz im Außenbereich wird die Qualität dieses Holzes auch in Europa geschätzt, woraus Bestrebungen entstanden, diese Baumart auf ihre Eignung zur Anpflanzung vor allem in Mitteleuropa zu prüfen. In den frühen 1...

Key message Bark thickness was shown to vary between regions, stands, and trees. Bark thickness prediction equations of different model complexity can be suggested depending on the purpose of application. Site and stand conditions, which influence variation of growth rate to a large extent, seem to have a strong influence on bark thickness, with be...

Bark thickness functions are used to predict inside-bark diameters of logs with outside-bark diameter measurements. The currently applied functions in Germany are based on measurements obtained in the 1970s. The objectives of this study were to review the currently used bark deduction values using new measurements and to test their suitability for...

Mobilizing timber resources from the smallest private forest ownership should be possible by ensuring straight information management along the logistics chain, including precise localization of trees and their ownership. Precise navigation during harvest operations by heavy forest machines is necessary to keep them on established skid trails to av...

Key message We provided a precise quantitative analysis of the factors at the origin of bark damage during harvesting operations and developed a model able to predict them accurately. The major factors were the distance of trees to skid trails, the intensity of removals, the harvesting system as well as the interactions between the distance of tree...

Declining stocks of softwoods in European forests and, simultaneously, increased use of wood in the building sector which is both desired and anticipated will presumably lead to a future gap in wood supply for the production of glued structural timber. At the same time, increasing stocks of hardwoods such as European beech (Fagus sylvatica L.) with...

A survey of cable logging contracts was conducted in 5 of the 8 Alpine countries, namely: France, Germany, Italy, Slovenia and Switzerland. The goals of the survey were to set a general reference for cable logging rates, to identify eventual differences between countries and to determine the effect of technical work parameters (i.e. piece size, rem...

To allow for information on successional changes in phytodiversity over time and space, as well as information on differences between clones and treatments, phytodiversity was monitored on a poplar short rotation coppice plantation in Oberschwaben, Southwest Germany, in four consecutive years. The investigated plantation was divided into two core a...

Context One of the most important wood defects affecting the value yield from European beech (Fagus sylvatica [L.]) logs is knots that are visible on the sawn wood surface. The non-invasive technology of X-ray computed tomography (CT) can be used for the assessment of log internal features, especially the geometry and position of knots before prima...

Context Current production from natural forests will not satisfy future world demand for timber and fuel wood, and new land management options are required. Aims We explore an innovative production system that combines the production of short rotation coppice in wide alleys with the production of high-value trees on narrow strips of land; it is an...

Knowledge about the wood quality of standing trees is crucial in that it serves as an excellent means for nearly all stages of the wood-supply chain. Better information about internal wood characteristics can be derived from the outside appearance by establishing a correlation between the bark characteristics of a stem and its internal quality. Thi...

Agroforestry at the Edge – Using field scarps and lynchets for high-grade wood production Possibilities to combine the production of valuable timber trees with traditional methods of agricultural management have increasingly been discussed in recent years. These cultivation methods are commonly termed agroforestry systems. Usually, the approach und...

Roundwood scanners utilizing X-ray computed tomography (CT) provide the information required for individual log-sawing optimization. However, errors in the automated detection of quality-relevant internal wood features for sawing control may lead to improper log positioning at breakdown, impairing the realization of value recovery potential. It is...

This paper presents results on the comparison of Arbotom impulse propagation measurements with x-ray based computed tomography scans. The methods had been applied to one log of Douglas fir to analyse the variation of the stem over its length. Tomograms of 20 cross sections at 50 cm distances were interpreted on the basis of gray value variation rep...

Several factors influence land availability for the growth of short rotation coppices (SRC) with fast-growing tree species, including the nationwide availability of agricultural land, economic efficiency, ecological impacts, political boundaries and environmental protection regulations. In this study, we analysed the growing potential of poplar and...

During timber harvest trees of the residual stand may suffer damages through bark lesions. This may happen associated either with felling or transportation processes. Although qualitative information on the causal factors is available, quantitative interdependences between the major factors and the resulting degree of damage are largely unknown so...

Cracks in softwood are an important defect that reduces the quality of sawn timber for construction purposes. As with all other quality reducing features in wood, it is of significant interest to know about their number and position in a log before sawing. On one hand, cracks are relatively easy to distinguish from wood by means of computer tomogra...

X-ray computed tomography (CT) is an effective scanning technology for imaging inner roundwood features. It is assumed that using this technology for log inspection prior to the first conversion could further optimise raw material utilisation. If the information obtained by CT scanning of a log shall be exploited in an industrial application, autom...

Classification and measurement of visible cracks in softwood logs and sawn timber Cracks as an attribute of logs are an important quality factor for the production of sawn timber. They can develop in the standing tree due to growth stresses or external influences, but also in felled trees due to tension releases or drying. The definitions for diffe...

Measurement and relevance for timber grading of cracks in softwood logs and sawn timber Cracks in timber of Abies alba Mill. and Picea abies (L.) Karst. are of high importance for the optical and mechanical quality of sawn timber products. A sample of 92 logs was assessed in detail before and after the sawing and drying process. The quantity, types...

The forest-based sector has been at the forefront in operationally implementing the sustainability concept, its associated principles and indicators for sustainable forest management. Several methods have been developed to study environmental impacts of forestry activities, but none of the existing tools address all the dimensions of sustainability...

Bark damages caused by logging activities occur at unacceptably high levels in forests of southwest Germany (28% of the trees). Furthermore, the level has increased in the last two decades. Spruce and beech as the major tree species are shown to display the highest level of bark damages (both 28%). Although foresters obviously tend to favour cuttin...

Common sale base for industrial timber used in the wood industry (e.g. pulp and paper or derived timber products) is in Germany the weight. Based on a sampling method the dry weight of wood substance of a certain delivery unit is determined at the mill gate according to uniform requirements. Additionally to the dry weight of the delivered timber it...

Allocation of suitable materials to mills, processes and products is crucial for the sustainability of the forestry wood chains. For successful allocation, information is needed about volumes and properties of the wood raw materials available in the forest resource in relation to industry demands. Mapping of properties in forest resources have been...

The forestry goal of producing large diameter wood seems contradictory to the sawmill industries goal of small to medium diameter wood. Amongst other things, the insufficient knowledge of wood properties of large diameter wood has led to examinations to finding a better way to evaluate wood quality. Based on outer characteristics the quality of fir...

Stocks of large dimension wood continue to increase, especially of medium quality classes B and C. Apart from newly built major sawmills, small and medium sized sawmills are also beginning to specialise in the processing of large diameter softwood of 3 – 6 m in length. In its turn, this is leading to changes in wood-logging techniques and quality g...

Nonlinear mixed-effects-models are applied successfully to estimate the cambial age of juvenile-mature wood transition in Scots pine sample trees from slow-grown stands. Till now segmented regression models are applied separately for each pith-to-bark-profile of wood density. The nonlinear mixed-effects-model overcomes this limitation while consist...

Segmented regression models are applied successfully to estimate the cambial age of juvenile-mature wood transition in Scots pine sample trees from slow-grown stands. Mean ring density, earlywood, and latewood density profiles from 99 trees were determined by X-ray densitometric analysis of disks taken at 4-m stem height. The cambial age of transit...

Die Steigerung der Ausbeute an Schaittholz hoher Tragfähigkeit durch maschinelle Sortierung ist für eine Maximierung der Wertschöpfung aus einheimischem Nadelrundholz unerläßlich. Zugleich kann damit die Konkkurrenzfähigkeit inländischen Bauschnittholzes gegenüber Schnittholzimporten aus Skandinavien und Übersee dokumentiert werden. Nicht zuletzt e...

Die Untersuchung ist dem Vergleich der Hand- und Klettersägenwertästung bei Fichte gewidmet. Es sollte insbesondere geklärt werden, welche Gefahren für den zu ästenden Baum und welche Ästungsqualität beim Einsatz der Klettersäge KS 31 resultieren. Das Probenmaterial stammt aus vier Fichtenbeständen im Schwarzwald. Die Ästungen liegen 13 bis 32 Jahr...

Zusammenfassung Empirischer Grundtatbestand in der Holzforschung bildet die Inhomogenität des Roh-und Werkstoffes Holz (Grammel 1989;Holz 1965). Verantwortlich hierfür sind verschiedene Einflußfaktoren, u. a. die Wachstumsbedingungen, aber auch die Position der Holzprobe im Baum. Mit der Darstellung einer multivariaten Datenanalysestrategie, der Da...

The inhomogeneity of wood as a raw and working material must be accepted as one of the basic empirical facts of wood science (GRAMMEL 1989; HOLZ 1965). Different influencing factors are responsible for this, e.g. growth conditions or the position of a sample in the tree. With the Multivariate Crossproduct-Partitioning (MCP) or Databox Partitioning...

The investigation describes the risks for the trees and the quality of pruning results if both hand pruning and pruning using climbing machines (KS31) is applied. The samples come from four stands in the Black Forest. The prunings date back 13 to 32 years. The average base diameter (vertical) of the pruned branches is 16 mm, the maximum 18 mm. The...

Various optical scanner technologies are used to detect the outer dimensions of the logs to a high precision; the standards for the measurement of external quality features are under discussion. Automated measurement of inner log features has been in the focus of considerations for some time. Appropriate technology for industrial application is on...