The Role of Disturbance in the Gap Dynamics of a Montane Rain Forest: An Application of a Tropical Forest Succession Model

Most discussions of forest disturbances have focused on large-scale phenomena (e.g., fire, volcanic eruptions) and man-induced changes (e.g., abandoned fields, cleared forest lands). Increasing attention, however, is being focused on the important influence of minor forest disturbances such as tree falls and canopy gaps on the composition, structure, and dynamics of forest communities. The relative importance of major and minor disturbances is, however, not yet clear. Observations in the wet tropics indicate that natural forest communities are composed of a “mosaic” of patches in different stages of successional and/or compositional maturity (Aubreville 1938; Richards 1952; Whitmore 1975, 1978). Watt (1947) interpreted such forest mosaics as a spatiotemporal patterning of phases linked in a regular cyclic succession. Each patch is thought to originate as a canopy gap formed by a localized disturbance such as tree falls or landslides. The degree of patchiness reflects the magnitude and periodicity of these perturbations (Whittaker and Levin 1977). High species richness, niche specialization, and chance factors also contribute to this dynamic patchwork in tropical rain forests (Knight 1975).