Fig. 2. Hypothetical example showing how differences in the disturbance severity - composition relationship could influence forest response to a clearcut. If a stand currently dominated by early-successional species is clear-cut, two different responses could occur. For ecosystem A, the disturbance is lower than the threshold disturbance severity necessary to maintain dominance by early-successional species, and the system would shift to high dominance by late-successional species after the harvest. For ecosystem B, the same harvest would allow early-successional species to be maintained. For either ecosystem, clear-cutting in a stand currently dominated by late-successional species (on upper part of curve), would not cause any significant change in composition.