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

Abstract

A survey has been made of the structure of the wood of Eucalyptusgigantea Hook. f. in relation to growing conditions in the Australian CapitalTerritory. Using the number of cells cut off by the cambium at various intervalsduring the growing season as a measure of growth, mathematical expressionshave been obtained for growth in young trees at ground level, breast height,.and half height; from these, growth rate curves have been derived. The timeof year at which growth commences, the relationship of vessel production tocommencement of growth, the formation of late wood, and the period of dormancyhave all been considered in detail. Variations in fibre dimensions havebeen investigated in relation to growth and it has been shown that in anyonegrowth ring the shortest fibres are found in the early wood and the longest inthe late wood. An intrinsic relationship between growth rate and fibre dimensions·has been established, and, at the junction between late and early wood, asudden change in fibre dimensions occurs corresponding to the discontinuity ingrowth rates. Anomalous woody tissue formed during severe drought conditionsis also described.