tailieunhanh - Báo cáo lâm nghiệp: "Compression stress in opposite wood of angiosperms: observations in chestnut, mani and poplar"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Compression stress in opposite wood of angiosperms: observations in chestnut, mani and poplar. | Ann. For. Sci. 63 2006 507-510 INRA EDP Sciences 2006 DOI forest 2006032 507 Original article Compression stress in opposite wood of angiosperms observations in chestnut mani and poplar Bruno CLAIRa b Tancrède Almerasc Junji SUGIYAMAa a Laboratory of Biomass Morphogenesis and Information Research Institute for Sustainable Humanosphere Kyoto University Uji-Kyoto 611-0011 Japan b Laboratoire de Mécanique et Génie Civil LMGC UMR 5508 CNRS Université Montpellier 2 Place E. Bataillon CC 48 34095 Montpellier Cedex 5 France c Laboratory of Bio-Material Physics Graduate School of Bioagricultural Sciences Nagoya University Nagoya 464-8601 Japan Received 24 May 2005 accepted 13 December 2005 Abstract - In order to face environmental constraints trees are able to re-orient their axes by controlling the stress level in the newly formed wood layers. Angiosperms and gymnosperms evolved into two distinct mechanisms the former produce a wood with large tension pre-stress on the upper side of the tilted axis while the latter produce a wood with large compression pre-stress on the lower side. In both cases the difference between this stress level and that of the opposite side in light tension generates the bending of the axis. However light values of compression were sometimes measured in the opposite side of angiosperms. By analysing old data on chestnut and mani and new data on poplar this study shows that these values were not measurement artefacts. This reveals that generating light compression stress in opposite wood contributes to improve the performance of the re-orientation mechanism. reaction wood compression wood tension wood opposite wood plant biomechanics growth stresses microfibrils angle Résumé - Contraintes de compression dans le bois oppose des angiospermes observation chez le châtaignier le manil et le peuplier. Pour s adapter à l environnement les arbres sont capables de contrôler l etat de contraintes des nouvelles couches de bois formé pour réorienter .

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