Juvenile/total foliage ratios inEucalyptus nitens and the growth of stands and individual trees

Summary

Individual trees and stands of two provenances ofEucalyptus nitens which have marked differences in retention of juvenile foliage were studied in four plantations at different elevations. The proportion of juvenile to total foliage and growth was measured at the end of the 2nd, 3rd and 4th year from establishment. Between the ages of 2 and 4 years annual stem volume increment increased in proportion to the amount of juvenile foliage retained. By age 4 years, stem volume of trees of the juvenile persistent form was significantly larger than that of the early adult form. Increasing differences in height growth with age between provenances, which were highly significant across sites by age 4, contributed to these differences in performance. There was some evidence that the largest trees of the juvenile-persistent form were those which combined mature foliage above juvenile foliage for the longest period during the transition from juvenile to mature foliage. In the early-adult form the largest trees were those which completed the transition to mature foliage rapidly. There was no difference in the ratio of foliage mass to basal area between the two forms. It is suggested that the faster growth of the juvenile-persistent form is related to higher leaf area index and not to foliage type. A provenance ofE. globulus which had a higher retention of juvenile foliage at age 4 than a second provenance had a lower stem volume, thus indicating that in this species early growth rate is not determined by foliage type.