Fig. 2

Outputs from a simple simulation model in which “basal area” and “composition” (percentage late successional species) both recover after disturbance. Composition involves persistence (the composition of surviving stems is unchanged immediately following disturbance), lag-times and integration (the composition of recruits depends on canopy openness over previous years with more early successional species surviving in more open conditions). a shows the simulated response over 400 years where a single event removes 90% of basal area in the tenth year. b shows an example where, from year ten onwards, disturbances occur with a 5% probability each year. If a disturbance event occurs it removes a randomly generated fraction of basal area between 0 to 100% (skewed to lower values). While both basal area and our measure of composition decline with disturbance, and increase with recovery, the Pearson product moment correlations (r) between these variables are often negative (as in the example)