Each individual gap is an internal environmental mosaic, not a uniform patch.

Evidence

Not only is the collection of gaps in a forest heterogeneous, but each gap is itself a mosaic that changes from the center to beneath the closed canopy. We are not aware of any published studies that address this whole range of variation, but there is a literature that shows, in broad outline, the nature and degree of environmental alteration associated with gaps. — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1385