Factors affecting growth and distribution of kauri (Agathis australis Salisb.) II. Effect of light intensity on seedling growth

Abstract

The effect of various light intensities on the growth of kauri seedlings is described. Daylight was screened to the required level with lath screens. There was no significant effect of light on seedling mortality in the light intensity range 0.40–0.02 full daylight. Seedling morphology was affected by light intensity, the ratios stem dry weight/root dry weight, stem length/root length, and fresh weight / dry weight increasing significantly with decreasing light intensity. Seedling growth was a linear function of log (light intensity), the growth rates and assimilation rates being similar to those for other forest tree seedlings. The compensation point was at 0.009 full daylight, close to the low light intensity limit to seedling establishment in the field but low compared with those of other tree seedlings. There was no high light intensity limit to seedling growth, such as that shown for seedling establishment in the field. The apparent discrepancy is discussed.