The growth rings in the wood of Australian araucarian conifers

THE GROWTH RINGS IN THE WOOD OF AUSTRALIAN ARAUCARIAN CONIFERS. By W. D. Frakcis. (Assistant Government Botanist, Botanic Gardens, Brisbane.) (Plates x-xi.) [Read 28th March, 1928.] Introduction. There is a widespread belief that the rings in the wood of Australian trees are not annual. Several circumstances have contributed to this assumption. The continent of Australia has been settled by people from the cool-temperate parts of Europe where many of the trees form fairly definite, yearly rings. In contrast with the cool-temperate parts of Europe and North America, Australia possesses a warmer climate and a more irregular rainfall. As an expression of climatic conditions the rings in the wood of trees grown in the warmer parts of Australia are much more uneven than those in the trees produced in Europe and the Northern United States of America and Canada. It remains for investigation to show to what extent the wood rings of Australian trees are of annual occurrence. This paper is intended as a contribution to the subject, although its scope is not confined to the duration of the rings. Curiosity as to the age of trees arises from both aesthetic and utilitarian considerations. Admiration of the giants of the forest frequently evokes the question of their age. It is recognized that trees are among the longest-living of all organisms. To the forester, the age. of timber-producing trees is an important economic question, as he bases upon it calculations relating to rate of production and cost of timber. In this respect foresters in Australia are at a disadvantage owing to the uncertain age of the constituent trees of the indigenous forests. In the United States of America a considerable amount of work has been done on the growth rings of trees. In addition to estimating the age of trees, some of the American investigators have employed the growth rings to interpret climatic conditions in the past. The big tree {Sequoia gigantea) has been extensively investigated from this point of view and data extending back as far as 1000 B.C. have been compiled from it. While perusing some of the American literature the writer met with observations and conclusions concerning the nature and occurrence of growth rings. As these details are pertinent to the present investigation a very brief summary of them will be given. A Partial Summary of American Work on Groioth Rings. Ernst Antevs (1925, p. 121) states that it is a well-known fact that young, vigorous trees are relatively far less influenced by external conditions than are ©Id individuals. Rings formed when the trees are very old may for several reasons not be good. Further on (1925, p. 124) he remarks that just as growth

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The growth rings in the wood of Australian araucarian conifers

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