Natural variation in shining gum, Eucalyptus nitens.  I. Growth rate and foliage characteristics, to age 3 years.  L. A. Pederick.  June 1977.  51 pp. (unpubl.)

SUMMARY

A comprehensive study of genetic variation in E. nitens was undertaken by means of provenance trials planted in 1972 at two sites, near Powelltown and on the Errinundra Plateau. The project was initiated after evidence of considerable variability in growth rate and foliage characteristics was obtained from a small pilot trial planted near Powelltown in 1968.

The 1972 trials contained plants of 56 seed sources, mainly individual parent trees, which were selected from localities grouped into six main regions of occurrence: Rubicon, Toorongo and Macalister in the Central Highlands of Victoria and West Gippsland; Errinundra in East Gippsland; and both Southern and Northern New South Wales. Row plots of 8 trees were used, with 6 replications at Powelltown and 4 at Errinundra.

Growth measurements were taken annually for three years, and the foliage characteristics studied included juvenile leaf shape, size and glaucousness of leaves, stem colour, and height at which juvenile leaves are replaced by adult leaves.

Results to three years of age, at both sites were similar. Genetic variation in growth rate and foliage characteristics was found at each of three levels of provenance: region of seed origin, locality within region, and individual tree within locality.

Young trees of Errinundra provenance were found to be quite distinct from those of other provenances because of their slower growth rate (particularly in diameter), narrower and less glaucous juvenile leaves, pink petioles and branchlets, and earlier change from juvenile to adult foliage (i.e. occurring at 1 to 2 years after planting, and at 1.5 to 2.5m above ground level).

Young trees of the other Victorian provenances (Rubicon, Toorongo, Macalister), with the exception of one portion of the Tooronga provenance, have very glaucous, broad juvenile leaves which persist for a longer time (the change to adult foliage takes place 2 to 4 years after planting and at 4 to 10m above ground level). Juvenile foliage was most persistent (up to 5 years from planting) in some families of trees derived from the highest altitude Victorian seed sources, a characteristic of apparent adaptive value on cold sites. The Toorongo provenance contained diverse leaf forms, for trees originating from seeds collected from Tanjil Bren and Mt Toorongo resembled the Errinundra type more than the nearby Toorongo Plateau type.

From Errinundra to the Northern New South Wales provenance there appears to be a cline for increasing leaf width and glaucousness, and for persistence of juvenile foliage.

Fastest average growth rate to 3 years was exhibited by Rubicon provenance, which grew twice as fast (stem volume) as Errinundra provenance at the Powelltown site, and three times as fast at the Errinundra site. That Tooronga Plateau and Macalister provenances were not much slower in growth than Rubicon. On account of the variability within provenances, it is likely that superior genotypes for growth rate could be found within each of these provenances, though the Rubicon provenance appears to be the most promising at this stage. There is evidence from the pilot trial at Powelltown at 6½ years after planting that the early (3-year-old) differences in growth rate observed between provenances in the main trial will be maintained for some years.

The report includes a detailed account of the natural distribution of the species.

Also published:

Pederick, L.A. (1979)  Natural variation in shining gum (Eucalyptus nitens).  Aust. For. Res. 9: 41-63.