Effects of forest plant species composition and physiognomy on bird and invertebrate communities were investigated in three discrete, relatively undisturbed forest types along a dry-wet soil moisture gradient. Discriminant function analysis produced a 100% floristic and a 78% vegetation structural discrimination between the three forest types. However, the bird communities of these different forest types were similar in species composition, and had lower densities than those encountered in superficially similar forests. Although an 81% discrimination between forest types was attained through analysis of ground surface invertebrates, measures of litter and aerial invertebrates were also of limited use as discriminators. Historical and biogeographic factors, as well as low nutritional levels in the soil and vegetation may be the causes of low bird and invertebrate density and diversity. It is concluded that floristics and vegetation structure have a minor influence on bird, and possibly on invertebrate community structure in the Knysna Forest.