The Relationship between Canopy Gaps and Topography in a Western Ecuadorian Rain Forest1

Abstract

The relationship between canopy gaps and topography was examined in 12 ha of wet rain forest in lowland western Ecuador. Canopy gap and topographical data were recorded on a 10- × 5-m grid system. Each grid point was categorized as belonging to a low canopy gap (≤5 m height), a high canopy gap (5–10 m height), or the non-gap forest (>10 m height). Slope position, altitude, slope, and surface rock all influenced proportional gap area. The gap relationship with slope position and slope angle varied with altitude. Proportional gap area was not related to drainage. Irrespective of altitude, the plateaus had the greatest proportion of low canopy gap followed by the valleys and upper slopes. The mid-slopes and ridges had the lowest proportion of low canopy gap. The proportions of high canopy gap had an almost converse relationship. As altitude decreased, the proportion of low canopy gap increased in the valleys and on the plateaus, but decreased on the ridges and upper slopes. The relationship of slope to the two gap types also varied with altitude, although no clear trend was evident. The processes controlling the observed topographical relationship of gaps are complex, and among other factors, may be linked to the distribution of live and dead treefalls. Topographic differences in the incidence of canopy gaps can potentially influence local species' distributions.