Determining factor of xylem maturation in Eucalyptus grandis planted in different latitudes and climatic divisions of South America: a view based on fiber length

Abstract

The objective of this study was to determine the factor of xylem maturation in Eucalyptus grandis W. Hill ex Maid. planted in four different latitudes and climatic divisions of South America, based on the pattern of the radial distribution of fiber length. In the plantation closest to the equator, the extent of juvenile wood is determined by distance from the pith and is consistent from tree to tree, regardless of growth rate. In contrast, in the plantation farthest from the equator, xylem maturation is controlled by cambial age and varies from tree to tree, depending on growth rate. To produce as much mature wood as early as possible in E. grandis planted closer to the equator, lateral growth should be accelerated from the early growing stage, because the formation of mature wood starts after a certain trunk diameter is reached. Conversely, in plantations far from the equator, it is necessary to first arrest lateral growth at an early growth stage and then accelerate lateral growth after a certain cambium age is reached.