The Variation of Pinus Radiata in the Nelson District, N.Z.

Abstract

1. Since its introduction into New Zealand in about 1860, Pinus radiata has been established in pure forests covering some 500,000 acres. Its future importance in forestry demands an examination of the possibility of improvement by selection. The first investigations have been to study the variation of the species in the Nelson district. It is considered that much of the visible variation is hereditary. 2. There is a wide range in habit, particularly in the crown and branch characters. 3. Bark varies from very rough to comparatively smooth. Differences in bark may possibly be correlated with differences in wood. 4. Using evidence of a variation in the proportion of binate to ternate leaf-fascicles in a tree, the validity of P. radiata var. binata as a taxonomic entity is questioned. 5. The great variation of the ovulate cones is discussed in relation to the descriptions of previous workers, and to the closely related species of Pinus. 6. Seeds vary in size, shape, texture, colour and markings. 7. Seedlings are described and there is an account of the first few months of a progeny trial. Growth differences between the sets of progeny were detected and some are thought to be mainly of genetic origin. 8. Variation in the development of lateral shoots in seedlings was observed. The growth of seedlings selected for these differences was studied in their second year. The initial differences were maintained in only a few young trees during this period. 9. Young trees 2-5 years old vary in habit and bud behaviour. 10. Trees differ in the number of branch whorls added each year. 11. Conclusion. The populations studied are recognised as one very variable species. None of the evidence indicates important discontinuities in the variation.