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1AWA Bulletin n.s., Vol. 11 (2), 1990: 115-140 IAWA·IUFRO WOOD ANATOMY SYMPOSIUM 1990 The third Euro-African regional wood anatomy symposium organised by the Wood Science and Technology Laboratories of the ETH (Swiss Federal Institute ofTechnology), Zürich, Switzerland, July 22-27, 1990. Organising Committee Prof. Dr. H.H. Bosshard, Honorary President Dr. L.J. Kucera, Executive Secretary and Local Host Ms. C. Dominquez, Symposium Office Secretary Dr. K. J. M. Bonsen, Deputy Executive Secretary lng. B.J.H. ter Welle, on behalf ofIAWA Prof. Dr. P. Baas, on behalf of IUFRO S 5.01 ABSTRACfS OF PAPERS AND POSTERS C. ANGELACCIO, A. SCffiRONE and B. SCHI MARIAN BABIAK, 1GOR CuNDERLfK and JO RONE, Dipartimento di Scienze deli' Ambiente ZEF KUDELA, Faculty of Wood Technology, Forestale e delle Sue Risorse, Facolta di University of Forestry and Wood Technol Agraria, Universita degli Studi della Tuscia, ogy, Department of Wood Science and Me Via S. Camillo de Lellis, 01100 Viterbo, chanical Wood, 96053 Zvolen, Czechoslo 1taly. - Wood anatomy of Quercus cre· vakia. - Permeability and structure of nata Lam. beech wood. Quercus crenata Lam. (Q. pseudosuber Flow of water and other liquids through G. Santi) is a natural hybrid between Q. cer beech wood (Fagus sylvatica L.) caused by ris x Q. suber. The species is widespread in the external pressure gradient is described by the mediterrane an basin, from France to Al the steady-state Darcy's law. The validity of bania. 1t occurs throughout Italy, usually as the law was proved up to a critical value. The single trees recognisable by their evergreen critical external pressure gradient obtained in and polymorphous leaves; the bark and acorn our experiments was 0.15 MPa/cm. The per cupules show intermediate characteristics be meability coefficient can characterise the num tween parents. The wooJ anatomy can be ber and quality of conducting elements in characterised as follows. wood and therefore should be related to its Macroscopic features: heartwood, sap structure. Poisseuille's law can be used to wood and tree rings are not easily distin describe this relation. It was shown that the guishable; broad rays very evident. Grain value of permeability coefficient obtained strongly twisted. from Darcy's law corresponds to that based Microscopic features: the vessels are 10- upon the vessel density and diameter. The cated in long radial chains. Their diameter results also confirmed that vessels are the ranges from 200 to 400).lm in the earlywood main conducting elements in beech wood. and from 100 to ISO ).lm in the latewood. Although their structure is heterogeneous the Perforations simple; tyloses abundant. The conducting system can be simulated as a rays are uniseriate and multiseriate, the latter bunch of parallel capillaries of a given length 25 to 30 cells wide. Additional information and an average radius. was obtained from dendroecological anal ysis. The wood of Q. crenata appears inter M. BARISKA, University of Stellenbosch, mediate in its wood anatomy between Q. cer Republic of South Africa. - Growth stress ris and Q. suber. splits in eucalypt mining timber. Downloaded from Brill.com10/08/2021 11:33:23AM via free access 116 IAWA Bulletin n.s., Vol. 11 (2), 1990 Between 20 and 50 million Rand a year is mately 0.3 microns, running both parallel and lost in South Africa due to growth stresses of perpendicular to the cell axis. Fibre cells sawn and mining timber. The mining indus showed litde damage due to collapse. tries are therefore promoting research into the forecasting of long tenn splitting damages in J.R. BARNETT, School of Plant Sciences, timber at felling or the splitting susceptibility University of Reading, Whiteknights, Read of standing trees. Investigations have reveal ing, RG6 2AS, U.K. - Cambial ultra ed two phases of split development: a fast structure in Aesculus hippocastanum one occurring in the first 6 days after felling during reactivation in spring. and a slow one following the first phase. The Cambium from Aesculus hippocastanum two phases of split development are strongly was sampled and prepared for transmission correlated. Thus, based on the extent of split electron microscopy at weekly intervals from ting in the fast phase, the long tenn split January to the end of ApriL The first signs of damage can be predicted with a high proba cambial reactivation were observed at the end bility. The sum of the split lengths measured of March in the form of the compIetion of during the fast phase also seem to be charac differentiation of sieve tube members and teristic of a tree and are strongly correlated companion cells, which had overwintered in with factors such as species or provenances the cambial zone after their formation at the of eucalypts, growth site conditions, tree' end of the previous season. The formation of dimensions and material properties. These new xylem elements was preceded by com findings indicate that it is possible to develop pIetion of differentiation of initial paren a simplified technique to predict the splitting chyma cells at the growth ring boundary, susceptibility of a standing tree with a given which had also spent the winter in an in probability. completely differentiated state. Evidence of metabolie activity in the 'dormant' tissues M. BARISKA, University of Stellenbosch, could be observed in the form of membrane Republic of South Africa. -Collapse phen and coated vesicle activity long before any omena in eucalypt species. cell differentiation could be detected. Trees belonging to the genus Eucalyptus are prone to develop damages due to cOllapse J.R. BARNEIT, I. WEATHERHEAD and H. soon after felling. A number of factors seem MILLER, School of Plant Sciences, Uni ver to cause collapse in eucalypts, namely: tran sity of Reading, Whiteknights, Reading, spiration in the living tree, moisture gra RG6 2AS, U.K. - Anatomical studies of dients, stem dimensions, interaction of the the developing graft union in Picea sitch surface tension of water with the anatomical ensis (Bong) Carr. structure and the material strength. There are, The development of the graf! union in Pi however, few facts available on the cOllapse cea sitchensis has been studied using light mechanism which takes place at the ultra microscopy and low temperature and conven structurallevel. Microscopic observations in tional scanning electron microscopy. The for dicate that essentially in the ray cells, the cell mation of a layer of resin between the graf! wall may at some stage break up into lamel components is followed by swelling of ray lae, which then fold parallel or perpendicular parenchyma cells which expand into the re to the cell axis. Two size ranges of folds gion between the scion and rootstock. These were detected: folds with a width of around cells divide to produce callus which forces 2-5 microns, and folds with a width of ap apart the scion and rootstock. There is also proximately 0.3 microns. These size rangts evidence of callus formation from cambial suggest that the first separation might take cells and from phloem parenchyma cells at place between the primary and secondary cell the graft interface. Differentiation of cambial wall layers. This would mostly generate cells within the callus provides the eventual folds running perpendicular to the cell axis. link between the cambia of scion and root The second separation would occur between stock. The first xylem elements produced the sublayers, thus creating folds of approxi- by this new cambium possesses features Downloaded from Brill.com10/08/2021 11:33:23AM via free access Abstracts I AWA-IUFRO Wood Anatomy Symposium 1990 117 characteristic of both primary and secondary versus moisture content and temperature xylem cells. Since cambial union, and the using the theory of rate processes and De subsequent fonnation of a vascular system bye's theory. According to these data, the common to xylem and rootstock does not phase state of bound water in wood is inter occur for about six weeks following grafting, mediate between liquid water and crystalline it is clear that the callus tissue must play an ice. The correction coefficient in the Van der important part in maintaining scion viability Waals state equation for bound water in during this period. wood versus moisture content has been cal culated. J. BAUCH*, H. VON HUNDT*, R. LIEBE Deviations of the potential barrier prevent REI**, G. WEIßMANN***, W. LANGE*** ing reorientation of dipolar groups of bound and H. KUBEL***, *InstituteofWoodBiol water in wood have been deterrnined. These ogy, Hamburg University, Leuschnerstraße values are sufficient to account for any mutu 91, 2050 Hamburg 80, **Institute of Ap al orientation of bound water molecules all plied Botany, Hamburg University, ***Insti over the investigated ranges of temperature tute ofWood Chemistry and Chemical Tech and moisture content. It was found (using the nology of Wood, Federal Research Centre Kirkwood-Frölich equation) that neighbour of Forestry and Forest Products, Hamburg, ing dipoles of bound water mainly have the F.R.G. - On the causes ofyellow and antiparallel orientation in wood with more brown discoloration of oak wood during than 10% moisture content and parallel orien drying. tation in wood with moisture content less Discolorations in oak wood during drying than 7%. lead to serious reduction in wood quality. In order to develop a specific prophylactic treat LIVIA BERGAMIN STROTZ*, L.J. KUCERA* ment preventing the yellow and brown dis and J. PAUL**, *Federal Institute of Tech colorations it was indispensable to detect the nology, Department for Wood Science, 8092 causes for these reactions. The yellow dis Zürich, Switzerland, and **Cambridge Instr. colorations were identified to be caused by GmbH, Heidelbergerstrasse 17, 6907-Nuss the mold fungus Paecilomyces variotii Bain. loch, F.R.G. -A programme to quan· and the reacting compounds are probably tify anatomical parameters on cross sec· hydrolysable tannins.