Abstract: Tree regeneration in forests is strongly influenced by the spatial pattern of the canopy.Gaps in the canopy provide the environmental conditions smaller trees need to grow and establishthemselves as canopy trees.
By introducing a suitable measure for successive disturbances at neighboring sites, we candistinguish three types of gap expansion: (1) Directional expansion driven by global environmentalconditions; (2) directional expansion caused by local processes; (3) gap expansion withoutdirection. Two simple 1-dimensional models illustrate the analytical power of this approach. Themethod reveals structural differences between three models for forest gap dynamics (2-state model,3-state model, and Shimagare/propagating-wave model) that an earlier study (based on the gap coverat a single time) was not able to detect.