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Keywords:

  • Herbivory;
  • plant defence;
  • habitat quality;
  • disturbance;
  • plant growth;
  • apparency

Summary

General patterns of herbivory and plant defence are summarized for a range of tree species studied in a lowland rain forest of Panama. Species growing in comparable micro-habitats differed by more than three orders of magnitude in the rates of herbivorous damage to mature leaves. Over 70% of this interspecific variation was statistically accounted for by differences in leaf characteristics. Species having tough, fibrous leaves with low nutritional value suffered little herbivory. Concentrations of immobile defences such as tannins and fibre were higher in species with long-lived leaves. Among species, there was also a significant negative correlation between growth rate and defence, and a positive correlation between growth and herbivory. These results suggest that differences in defence among species are due to interspecific differences in intrinsic growth rates and not to differences in apparency.

Theories of plant defence based on interspecific differences in growth rate and apparency are combined in a single general model of plant defence. This model follows Grime's triangular classification of plant strategies and assumes that quality of habitat and rate of disturbance are both important determinants of plant defence. Predictions are made as to the types of defensive properties expected in stress-tolerant, competitive and ruderal species.