Wood Structure in Relation to Growth in Eucalyptus Gigantea Hook. F

Abstract

A survey was made of the structure of the wood of E. gigantea in relation to growing conditions in the Australian Capital Territory. Using the number of cells cut off by the cambium at various intervals during the growing season as a measure of growth, mathematical expressions were obtained for growth in young trees at ground level, breast height, and half height; from these, growth rate curves were derived. The time of year at which growth commences, the relationship of vessel production to commencement of growth, the formation of late wood, and the period of dormancy were all considered in detail. Variations in fiber dimensions were investigated in relation to growth and it was shown that in any one growth ring the shortest fibers are found in the early wood and the longest in the late wood. An intrinsic relationship between growth rate and fiber dimensions was established, and, at the junction between late and early wood, a sudden change in fiber dimensions occurs corresponding to the discontinuity in growth rates. Anomalous woody tissue formed during severe drought conditions is also described.