CANOPY STRUCTURE OF A TROPICAL RAIN-FOREST AND THE NATURE OF AN UNSTRATIFIED UPPER LAYER

1. The two-dimensional distribution of foliage density was investigated in a vertical canopy section of forest in West Sumatra, using analysis of variance. 2. No significant continuous upper canopy layer could be found. However, there was significant stratification with a dense foliage layer below 15 m. The structure of the upper canopy (higher than 15 m) had an erect structure rather than being stratified. 3. Two hypotheses were examined to explain the unstratified upper canopy structure: (i) it was due to incomplete growth in height of the trees, leading to an unstratified forest canopy even in mono-specific forest, or (ii) it was caused by a mixture of species with different potential for height growth. The latter hypothesis was supported by the observations on tree growth.