THE USE OF EXOTIC FOREST TREES

Abstract

SUMMARY Australian trees are useful exotics in a number of countries. Within Australia trees from other countries are of growing importance in the local timber industry. In the course of this exchange of trees, experience has been gained on the principles which should be followed in choosing exotics and avoiding unnecessary silvicultural failures or human disappointments. This paper outlines these principles and, describes characteristics which are common to trees which have proved successful as exotics. The undoubted potential of exotics should be exploited by developing countries. This potential is largely dependent on the fact that trees can be introduced into a new country without the pests that have evolved with them in their homeland, and they may be immune to many pests of the new country. This immunity can lead to a vigour that could only be developed in native trees by intensive selection and breeding. Exotic forest trees have shown the most spectacular growth when planted on good soils in favourable climates, but they are also valuable in improving the yields from relatively poor soils. The healthy growth of well chosen exotics has brought artificial nutrition of plantations into the realm of practicable forest treatment. Exotics may be spectacularly successful in an early stage of the development of a society where the need is for poles or fuel which can be cut by simple implements, but they may be a disappointment later when the same society requires sawn timber from larger trees which must be broken down in an expensive factory. A lead is provided to the extensive literature on world experience with exotic forest trees.