THE SPATIAL-DISTRIBUTION OF HERBIVORY, MINES AND GALLS WITHIN AN AUSTRALIAN RAIN-FOREST TREE

The spatial distribution of herbivory, mines and galls was investigated within the crowns of the canopy tree Argyrodendron actinophyllum (Sterculiaceae) in a subtropical rain forest near Brisbane, Australia. Apparent leaf damage amounted to 11 percent of leaf area removed, was significantly higher in sun than in shade leaves, was not significantly higher in the upper crown (> 25 m) than in the lower crown (15-25 m), and did not differ significantly among compass orientations. Leaf biomass removed by herbivores was significantly higher in the upper crown and in sun samples. Overall leaf damage, including leaflets entirely eaten and leaf-mining, ranged from 11 percent to 19 percent. However, actual leaf consumption was mainly restricted to young leaves, and amounted to about 16 percent; this was more dependent on the location of isolated, abundant, and sunny patches of young foliage than on local differences in foliar nutrient characteristics, such as total nitrogen and water content. Lepidopteran biomass and numbers were correlated with leaf damage in the samples. Leaf-mining, averaging 31 mines per m2 of leaf area, was significantly higher in the lower canopy. Gall densities approached three galls per m2 of leaf area. Galled leaves were significantly larger and less heavily grazed. Patterns of herbivory and leaf-mining observed are discussed in light of current information and theories relevant to insect-plant interactions in rain forests.