Provenance trials of Pinus strobus, P. monticola and P. lambertiana in the Mansfield Forest District.  L. A. Pederick and J. McDonald.  December 1979.  18 pp. (unpubl.)

SUMMARY

Provenance trials with three species of five-needle pine from North America (Pinus strobus, 60 provenances; P. monticola, 5 provenances; and P. lambertiana, 5 provenances) were established in 1968 at Toombullup near Mansfield. Results from three measurements during the following ten year period were analysed, and the provenances were assessed on their prospects for operational planting.

The southernmost provenances of P. strobus grew fastest both as seedlings in the nursery and as young trees after planting. Height growth was negatively correlated with latitude of seed source, and positively correlated with length of growing period of seedlings of each provenance in the first year. At least part of the growth superiority of the southern provenances may have been due to their ability to grow for a longer period into the autumn, as a result of adaptation to the less rigorous climate in the southern areas. Although the southern provenances remained the largest trees after 10 years, the correlations between height and latitude of seed source, and between height and date of bud set, became progressively weaker with increasing age of the trial, and were no longer significant after six years. This suggests that, as the trees grow older, the growth rates of provenances may not be as responsive to the set of environmental factors to which they were adapted as seedlings.

After 10 years the best growth of P. monticola was achieved by plants derived from seeds from a plantation at Bago, N.S.W. This superiority may be attributed partly to the effect of natural selection during one generation in Australia, though it is more likely that it originated in a better provenance than the other four that were represented.

The P. lambertiana provenances were represented by seedlings of different ages when first planted, and their height at 10 years was strongly related to their average size at time of planting. This trial was therefore considered a species trial rather than a provenance trial.

Of the three species, P. monticola was the tallest at age 10 years. Although it was much shorter than adjacent P. radiata of the same age (5.0 m compared with 12.0 m), P. monticola had attained an annual growth rate of nearly 1.0 m, so the relative difference in size between the two species may gradually decrease in the future. The best provenance of the five-needle pines, Bago P. monticola, did not appear to be suitable for operational planting because of its slow nursery growth and problems with establishment after planting.