Kraft fibre and pulp qualities of 29 trees of New Zealand grown Eucalyptus nitens

Abstract

There is a need to determine the between tree variation in the wood properties and kraft fibre and pulp qualities of softwoods and hardwoods that grow well in New Zealand. This information will be used in the planning and management of end-product directed plantation forests and tree-breeding programs. Variation among 29 individual trees of E. nitens is extremely high; for the individual tree chip samples the basic density range is 390-556kg/m 3 , total lignin content 25.1-29.7%, and kraft pulp yield 54-59%. Between tree variation in some important kraft pulp properties are: fibre length (0.780.95mm), fibre perimeter (19.0-21.6mm), wall area (coarseness) (53-70mm 2 ), and handsheet bulk at 500 PFI mill rev (1.59-1.37cm 3 /g).The fibre width:thickness ratio and length combination (r 2 = 0.67), and the chip density and length combination (r 2 = 0.64) are the best predictors of handsheet bulk. Fibres are curled and consequently 'shortened' by pulp bleaching.