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The tree-ring lab at BOKU University, Vienna, Austria has been sampling and dating by means of dendrochronology in the eastern part of Austria since 1996. Among other objects, the roof constructions of 982 historical buildings were analysed, resulting in 13 916 samples. The time span extends from the oldest roof truss at a church in Salzburg, dated to 1135, to the youngest in Vienna, dated to 1997. The aim of present paper is to provide an overview of the findings on historical roof constructions in Austria based on data collected over the last 27 years. Out of the total sample elements, 69.0% were made out of Norway spruce, followed by silver fir with 19.6%. All other species played a minor role: pine (5.0%), larch (3.6%), oak (2.7%), followed by a few elements made of stone pine, elm, beech, and poplar. The proportion of wood species reflects the significant influence of alpine regions. Within the city of Vienna, where all building timber was rafted, the amount of spruce wood is 72.3%. There were no clear visible changes in the wood species share over time. Along with dendro-dating, building historians have been analyzing the typology of roof trusses and the changes within time. It was possible to see clear alterations from simple rafter constructions to huge multi-level constructions with standing and sometimes hanging columns and roof constructions with lying posts (in the plane of the rafters) that transition back to constructions with standing columns.

The website oldestwoodenobjects.net serves as a platform for the scientific community to collect, display and share early traces of wood utilization. It also serves educational purposes, to teach a wide audience about how multifunctional and durable wood can be, when wisely used. The collection of objects is large and diverse, ranging from simple tools for hunting, like spears, to musical instruments of the high culture, such as violins. The first means of transport, dugout canoes or early infrastructure, like water wells, are remarkably old. Due to weathering, early buildings or constructions are poorly or only partially preserved. But some sacred buildings that are still in use today have an impressive age. At the time of writing this manuscript, a total of 211 prehistoric and historic wooden objects from around the globe were gathered and can be compared at the online application. The oldest item on the list is from 300 000 years before present. To continue expanding the database, the community is encouraged to contribute new entries.

Wooden shingles have been known in Europe and other regions worldwide for several thousands of years. They are usually split, and according to handicraft rules, as well as historical literature, a split surface has many advantages. It is more flexible, more elastic, stronger, and less exposed to cupping than a sawn surface because no fibers have been cut. It also follows wood rays; it is more durable than a sawn surface because cut fibers absorb more moisture, creating good conditions for fungal growth. However, because sawing is the main procedure for dividing logs into timber, sawn boards are currently used for roofing. The short life span of such roofing has often been discussed by craftsmen. In this study, a 37-year-old roofing was evaluated to determine the important parameters of high-durability sawn boards. Results showed that the presence of juvenile wood, fiber deviations, and knots reduced the durability of these boards. Therefore, sawn boards of the same wood quality as split shingles may have the same durability.

The Vienna Hofburg is a large complex of buildings of unique historic importance with historical wooden constructions from the 13th to the 20th century. Within its wooden roof constructions, rafting wedges were found, which proves that the timber used did not originate in the surroundings of Vienna but had to be transported to the city. An ascertainment of these residual traces in eleven wings of the Hofburg building was made; five different types (within two main groups) of rafting wedges and withies (softened twigs that can be used like short ropes to tie trunks together) were defined: (1) simple flat wedges, driven into the fresh wood; (2) round or squared wedges, with or without withies driven into bored wholes. It was not possible to trace back the origin of the construction timber by means of that typology. However, the combination of dendroprovenancing and historic records found in archives led to first results.

Wood in Austria has been an indispensable source of energy, but also, a crucial building material. In the field of dendroarchaeology the timeline between raw material harvest and finalisation of a wooden construction is a crucial piece of puzzle in understanding building history. This paper aims to provide an overview on historical timber supply in Austria by examining the felling and debarking methods, as recorded in old literature and, from the visible evidence on beams in wooden constructions. Historically, depending on the size and location of a building, a small or extended supply chain of timber was required. These generally consisted of logs travelling via streams and rivers, and possibly beforehand passing through sluices and log slides, being skidded by horses and oxen, and being moved by manpower on sleighs, or simply on the forest floor. The seasonal working steps of the logging process included felling, debranching, debarking, cutting to length, and the start of the transportation process. Debarking was a specific focus in this investigation, as the appearance of bast (the inner bark of trees from which ropes were made) or even bark residues on the waney edge (outermost growth ring underneath the bark), may provide a clue to the felling time of year. These indications of the cutting season have been noticed during dendrochronological sampling of beams in historical buildings. Improved knowledge of them may contribute to future research of these buildings.

Wood is one of the most important sustainable natural resources. Throughout centuries, large cities as well as regions of very high wood demand (for example, areas of salt production and iron processing) had to be supplied with wood for building and burning. One of the largest forests in Austria can be found in the National Park covering the range of mountains called “Limestone Alps.” Within this region, a wide network of dams was set up to transport single logs (“Holztrift”). Due to the dendrochronological dating of the surviving dams, regional chronologies spanning a length of almost 600 years for Norway spruce, Silver fir and European larch were set up. These chronologies serve as the background for dendro-provenancing timber. Dendro-provenancing checks the similarities between samples and different regional chronologies. The highest statistical figures give hints of the origins of the wood. Archival analyses show that many logs were transported to Vienna as rafts. For example, in 1865, more than 1504 rafts arrived in Vienna, all from different origins. The logs were used as building material as well as for burning. Further archival analyses showed that logs from this region were also used for building the roof of the Hofburg Castle in Vienna. Several hundred samples from the roof construction were dendrochronologically dated and used for dendro-provenancing. The origin of the logs was confirmed to be the wider region of the Northern alpine foothills. This meant that rafts from the rivers Alm and Traun as well as from the rivers Steyr and Enns had floated down to Vienna.

Hand spinning has become increasingly popular as a recovery of the traditional techniques of natural fibre processing and cultural heritage protection. Modern spinning wheels are usually made of easily available wood species, particularly hardwoods, and one spinning wheel usually consists of one or two species. However, the wood species that were used for the individual parts of old spinning wheels in Central Europe are still unknown. To improve our understanding of traditional craftsmen and their skills, we investigated old spinning wheels that originated from Central Europe in the 19th and the 20th century. In this study, we present a collection of 643 samples from 54 artefacts representing the region between the European Alps and the Western Carpathians. Spinning wheels were usually made of 3 to 5 wood species, and the species selection varied among regions. Generally, high wood density (> 600 kg.m−3) species prevailed in Austria and Western Slovakia, but lower wood density (< 600 kg.m−3) species were preferred in the south-eastern Czech Republic. Easily workable species were used for the production of the spinning wheels, primarily Tilia, Fagus sylvatica, Picea abies, and Acer. In addition to these species, a high proportion of fruit-bearing trees and three shrubs were identified. Wood anatomy, as an important scientific method, contributed to understanding the reasons for species selection and the suitability of their properties which will enable the conservation of sustainable folk traditions and crafts, as well as the knowledge of traditional craftsmen.

Intra-annual density fluctuations (IADFs) in tree rings are generally considered structural anomalies caused by deviations from the “normal course” of xylogenesis during the growing season. This definition is based on the bias that, under “normal conditions”, cambial activity stops once a year. Each tree ring can thus be dated to one calendar year, which is one of the principles of dendrochronology. The formation of IADFs can be triggered directly by environmental changes, especially in precipitation and temperature, that affect cambial activity and cell differentiation. It can also be the result of limited photosynthesis, due to defoliation induced by biotic or abiotic constraints. Often indicated with alternative terms, IADFs were first described in the 1930s, and recently reported for many trees and shrubs from different ecosystems throughout the world, particularly for Mediterranean species. Different types of IADFs have been detected; their formation and structural properties depend on many factors including tree genotype, age, size, rooting depth, habitat, soil, climate, photosynthetic activity, and allocation strategies. Whether IADFs affect the adaptive capability of plants remains, however, unclear. We provide an overview of the main anatomical features of IADFs and their occurrence in tree rings from various environments and climatic regimes. We propose a simplified way of classifying them and discuss the hypotheses about their functional role and the factors triggering their formation. To understand the ecological role of IADFs better, we recommend a multidisciplinary approach, involving wood anatomy, dendroecology, and stable isotopes, which has already been applied for Mediterranean species. We conclude by considering that IADFs appear to be the “rule” rather than “anomalies” in some ecosystems where they help plants cope with fluctuating environmental conditions. Moreover, their anatomical structure represents a valuable proxy of past climatic conditions at a sub-seasonal resolution and may be relevant to adapt hydraulic functioning of living trees to changing climatic conditions.

The genus Larix is exceptional for its high content of extractives in the heartwood, with the dominant component arabinogalactan found abundantly in cell lumens of tracheids. On parallel samples prepared from 20 European, Japanese and hybrid larch trees (Larix decidua Mill., L. kaempferi Carr., and L. decidua × L. kaempferi, respectively) extractive contents and mechanical parameters were measured. The hot-water extractives in the heartwood had a significant effect on transversal compression strength and Young's Modulus. In heartwood, increasing extractive content went hand-in-hand with better mechanical properties in the transverse direction. The extraction procedure led to negligible changes in the sapwood. Anatomically the extractive-filled tracheids showed a tendency of being arranged radially, closely to wood rays. The extractive arabinogalactan in larch heartwood has multiple effects on different aspects of wood quality, among which is lateral mechanical enforcement.

Longitudinal shear strength and shear modulus of spruce and larch wood with a maximum of micro- and macro-structural variability was determined using a new testing method. Oven-dry density and slope of grain were measured after the shear tests. For the spruce wood samples, a data set of fiber and cell wall properties, i.e., lignin content, microfibril angle, fiber length, lumen diameter, cell wall thickness, latewood proportion, and ring width, was available. A multiple linear regression analysis of all fiber and cell wall properties showed a significant, but not very strong effect on the variability of shear strength (R2 = 0.21). It is thus demonstrated that micro-structural variability plays a minor role in the variability of shear properties. By contrast, a multiple linear regression involving shear modulus, density, and slope of grain as three independent variables revealed an excellent possibility to model the variability of shear strength (R2 = 0.72). This study demonstrates the potential for non-destructive evaluation of the shear strength of solid wood.

This paper presents an analysis of 16 anatomical variables measured on 20 spruce trees [Picea abies (L.) Karst.] from sites in the managed forest district Seyde, Eastern Ore Mountains, south of Dresden, Germany. Ring width and latewood proportion did not show significant relationships with monthly climatic data, whereas maximum density, latewood cell-wall proportion and latewood density were highly correlated with temperature and precipitation. The climatic signals expressed in resin duct density, ray height, tracheid length and microfibril angles were less pronounced. Of 16 tree-ring parameters, densitometry – as an indirect measure of xylem anatomy – has again shown its great potential to record climatic conditions.