REGENERATION OF KAURI

Press, Volume LXXXV, Issue 25713, 27 January 1949, Page 3

REGENERATION OF KAURI

AUCKLAND STUDENT’S RESEARCH

GOOD GROWTH BENEATH TEA-TREE ‘‘The Press” Special Service

AUCKLAND, January 24. Interesting conclusions on the regeneration of kauri have been reached after two years of patient work by Mr R. V. Mirams, .an Auckland University College student. After counting and comparing hundreds of kauris, from seedlings to mature trees, in two areas in the Waitakere ranges. Mr Mirams has shown by quantitative methods that regeneration takes place best beneath tea-tree scrub and is poorest under mature kauri. He has also found that young trees produce more seed than mature ones.

Mr Mirams has spent the last two years studying kauris for a master of science degree, which he completed last year. Since the beginning of 1947 he has held an Auckland City Council research scholarship in botany, and, with the aid of the scholarship, will conduct further research this year. His

experiments have been made in the Cascades Kauri Park in the Waitakeres and at the 58-acre property at Swanson owned by the university college. The study was made on 30 pieces of land on which kauri at various stages of development was already growing. These areas were selected more or less at random and were often several miles from one another. Ten of the plots w’ere in tea-tree scrub and the others in kauri forest, and the total area of the actual plots involved amounted to about three-quarters of an acre.

After selecting an area for work, Mr Mirams carefully taped out a plot 10 metres square and then further subdivided it into strips each one metre wide. He then counted the trees in each strip, tabulating them into six age classes ranging from small seedlings a few months old through larger seedlings to mature trees. Mature Forest Conditions Mr Mirams found that the kauri regenerated best in the tea-tree scrub, where he counted the greatest number of young seedlings. The kauri did not appear to be able to reproduce itself well in the mature forest. By actual count there were in tea-tree more than twice as many seedlings as in a similar area in the mature forest. All seed which germinated under tea-tree had to be carried into the area, most probably by the wind, from adult trees often some distance away, while a far greater quantity of seed would naturally fall to the ground under mature kauri. Mr Mirams therefore deduced that there must be some factor present in tea-tree vegetation which allowed the seed to reproduce more readily than it did under the kauri canopy. An attempt was also made by Mr Mirams to discover how much seed an individual tree would produce. To do this it was necessary to obtain cones. Because kauri cones do not drop to the ground but break up on the tree, scattering their seed, it was necessary for a tree climber to scale some kauris and gather their cones. As this work was rather hazardous,. Mr Mirams was not able to obtain ns many cones as he would have liked. The results, however, indicated that trees which were not mature as far as form and size were concerned appeared to produce the greatest quantity of sound seed. Only one-third to one-half of the total amount of seed produced by one cone was sound and able to germinate, and even that amount did not keep its germinating capacity indefinitely. Mr Mirams also found that the amount of sound seed obtained from a cone was strongly corellated with the size of the cone. Germination Influences • The amount of light necessary for germination was another aspect investigated by Mr Mirams. He planted seeds in various positions to determine whether position had any effect on germination. For most of these experiments a standard nursery soil was used, but in some cases seeds were planted in soil brought from a kauri forest. The results showed that, irrespective of the position in which the seed was sown, there wasa'far' greater germination under maximum lighting conditions than when the

seeds grew under reduced illumination. The position of the seed did have an effect on germination, but the main factor was the one of light. Attempts were also made to grow kauris in the various areas plotted for the earlier experiments, but of soma 25.000 seeds sown dess than 100 germinated. Mr Mirams concluded that vast quantities of seed must be necessary for the production of only one kauri .seedling. Possible reasons for the poor gepynination were the inroads of animals, insufficient or too much water on the soil, and attacks by birds, insects and certain fungi.