FUNCTIONAL RELATIONSHIPS BETWEEN WOOD STRUCTURE AND VULNERABILITY TO XYLEM CAVITATION IN RACES OF EUCALYPTUS GLOBULUS DIFFERING IN WOOD DENSITY

BAROTTO AJ; MONTEOLIVA S; GYENGE J; MARTINEZ MEIER A; FERNANDEZ ME

TREE PHYSIOLOGY

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2018 vol. 38 p. 243 - 251

0829-318X

Wood density can be considered as a measure of the internal wood structure, and it is usually used as a proxy measure of other mechanical and functional traits. Eucalyptus is one of the most important commercial forestry genera worldwide, but the relationship between wood density and vulnerability to cavitation in this genus has been little studied. The analysis is hampered (among other things) by its anatomical complexity, so it becomes necessary to address more complex techniques and analyses to elucidate the way in which the different anatomical elements are functionally integrated. In this study, vulnerability to cavitation in two races of Eucalyptus globulus with different wood density was evaluated through Path analysis, a multivariate method that allows evaluating models of causal relationship between variables. A model relating anatomical variables with wood properties and functional parameters was proposed and tested. We found significant differences in wood basic density and vulnerability to cavitation between races. The main exogenous variables predicting vulnerability to cavitation were vessel hydraulic diameter and fibre wall fraction. Fibre wall fraction showed a direct impact on wood basic density and the slope of vulnerability curve, and an indirect and negative effect over P50 through them. Hydraulic diameter showed a direct negative effect on P50, but an indirect and positive influence over this variable through wood density on the one hand, and through ks max and slope on the other. Our results highlight the complexity of the relationship between xylem efficiency and safety in species with solitary vessels such as Eucalyptus spp, with no evident compromise at the intraspecific level.