Variations temporelles à haute résolution des propriétés du bois d’Eucalyptus globulus irrigués et non irrigués

Abstract

Abstract• Environmental determinants of wood properties variation were examined in Eucalyptus globulus, a globally important hardwood plantation species, in southern Tasmania, Australia.• Radial variation in wood properties, measured with the SilviScan system, were re-scaled from distance to time abscissa using stem radial growth data measured with dendrometers. With this re-scaled data it was possible to evaluate how water availability and temperature affected wood density, microfibril angle (MFA) and fibre and vessel transverse dimensions in irrigated and non-irrigated trees.• Wood density, fibre radial diameter and MFA were sensitive to water availability. Wood density increased and fibre radial diameter decreased in response to reduced water availability. When high water availability was maintained, wood density was negatively correlated with temperature. Together, temperature and soil matric potential explained about 60% of temporal variation in wood density variation. In contrast MFA was not related to temperature but decreased with increasing water stress. Slower growing trees also had lower MFA than faster growing trees. Slower growing trees had a larger number of vessels per unit area of wood than faster growing trees within this even aged stand. However, vessel radius to the 4th power was significantly higher in faster growing trees than in slower growing trees.• Overall, E. globulus wood properties were sensitive to temporal changes in environmental conditions (particularly water availability) and associated growth rates. The data provided support for the hypothesis that growth rates are hydraulically mediated. Mots-clés :développement du xylème / dendromètres / taux de croissance à haute résolution / hydraulique des plantes Résumé -Variations temporelles à haute résolution des propriétés du bois d'Eucalyptus globulus irrigués et non irrigués.• Nous avons analysé les déterminants environnementaux des variations des propriétés du bois d'Eucalyptus globulus qui est une importante essence feuillue de plantation du sud de la Tasmanie en Australie.• La variation radiale des propriétés du bois -mesurées avec l'outil Silviscan -a été convertie en variation temporelle par le biais des mesures de la croissance radiale obtenues avec des dendromètres. Avec ces données recalibrées il a été possible d'évaluer comment la disponibilité en eau et la tempé-rature ont affecté la densité du bois, l'angle des microfibrilles ainsi que les dimensions transversale des fibres et vaisseaux pour les arbres irrigués et non irrigués.• La densité du bois, le diamètre radial des fibres et l'angle des microfibrilles sont sensibles à la disponibilité en eau. En réponse à une réduction de la disponibilité en eau on observe que la densité du bois augmente et le diamètre radial des fibres diminue. Lorsqu'un niveau élevé de disponibilité en eau est maintenu alors la densité du bois apparaît négativement corrélée avec la température. La température et le potentiel matriciel du sol expliquent ensemble environ 60 % de la variation temporel...

The anatomical traits of trunk wood and their relevance to oak (Quercus robur L.) vitality

“…A concomitant decrease in earlywood vessels' density per unit of the annual ring surface was noted: the lowest for the trees from the group of dead oaks and the highest for the healthy ones, contributing to the reduction in the potential hydraulic conductivity of oak trees represented particularly in the groups of declining and dead trees. The increase in the vessel diameter and the consequent improved water conductivity possibly constitute a mechanism of adaptation to changing environmental conditions and a response to stress factors affecting the growth potential and reproduction capacity of the tree (Drew et al 2009). This is in line with the Tyree's hypothesis (2003), which assumes that the growth rates are hydraulically mediated.…”

Influence of climate variables in the initial growth of Corymbia citriodora and different species of eucalyptus

“…The collar diameter growth peaks in December and January are associated with high precipitation levels and minimal average temperature increases (DREW et al, 2009). The collar diameter growth rate is highly temperatureregulated (DREW et al, 2008, SETTE JR et al, 2010.…”

Efeito da disponibilidade hídrica e da aplicação de potássio e sódio no crescimento em diâmetro do tronco de árvores de Eucalyptus grandis

“…As faixas dendrométricas de aço, segundo Marcati (2000) podem contrair na estação do inverno e dilatar no verão ocasionando variação dimensional no seu comprimento. Segundo Drew (2009) os dendrômetros são uma ferramenta de alta precisão na análise temporal e espacial do incremento em diâmetro do tronco das árvores. O autor cita, ainda, os trabalhos de Dobbs (1969), Lapoint e Van Cleve (1971) e Pook e Hall (1976) que obtiveram uma precisão de leitura do incremento do tronco das árvores de 0,038; 0,02 e 0,005 mm, respectivamente, comprovando a sua acurácia na experimentação florestal.…”