of softwoods and its functionsTrees are large engineering structures that have to withstand major wind and static forces and translocate considerable volumes of water. Natural selection has over millions of years optimised tree structure to maximise survival of the species. Naturally this process does not necessarily optimise the properties of the resultant lumber such as hardness, stiffness and strength. Such wood properties can now be improved by genetic engineering and tree breeding. If this is done without understanding the contribution of wood structure to tree survival, this can lead to increased susceptibility to windthrow, splitting and branch damage in the standing tree and internal checking and collapse during wood drying. As a first step to quantifying these potential problems this paper reviews latest findings on the nanostructure of the cell wall of softwoods and then discusses the probable relationships between microfibril directions in the secondary cell wall layers and potential threats to the survival of trees such as excessive vibration and crack propagation.
Nanostruktur der Zellwand des Nadelholzes und ihre Funktion im lebenden BaumB~iume k6nnen als grofie Holzkonstruktionen aufgefafit werden, die starken statischen und Windbelastungen ausgesetzt sind sowie grofie Mengen an Wasser transportieren. Die natfirliche Selektion hat fiber Jahrmillionen die Holzstruktur und damit das Oberleben der Arten optimiert. Dieser Prozess optimierte nicht notwendigerweise die resultierenden Eigenschaften yon Schnittholz wie H/irte, Steifheit und Festigkeit. Solche Holzeigenschaften k6nnen inzwischen durch Zfichtung und genetische Manipulation verbessert werden. Werden diese Versuche unternommen, ohne die Bedeutung der Holzstruktur ffir das Oberleben des Baumes zu kennen, so kann das zu verst/irkter Anf~lligkeit fiir Windbruch, Risse und Astsch/iden am stehenden Baum sowie zu Riflbildung und Kollaps w/ihrend des Trocknens f-fihren. Als ersten Schritt zur Quantifizierung dieser m6glichen Probleme gibt diese Arbeit einen Uberblick fiber jfingste Erkenntnisse zur Nanostruktur der Zellwand in Nadelholz. Daran anschliefiend erfolgt eine Diskussion wahrscheinlicher Beziehungen zwischen der Orientierung der Mikrofibrillen in den Sekund~irw/inden und m6glichen Gefahren ffir das Uberleben des Baumes wie fiberm~iflige Vibrationen und Rififortpflanzung.
Importance of wood structure for tree survival and tree breedingThe general importance of wood structure for the functions of a tree -a masterpiece of evolutionary design -is quite obvious. This structure makes it possible for huge amounts of biomass to be supported by astonishingly slim stems to heights of sometimes more than 50 metres. Even large static and dynamic forces of gravity and wind-loads are usually accommodated without damage to the tree. Additionally, the same wood structure provides for remarkably efficient water transport from the roots to the crown without causing collapse of the wood cell walls by the high water tension necessary for this transport. With t...
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