摘要: In virgin forests, individual trees tend to be succeeded in time by those of another species. The phenomenon was recognized a French forester and named "alternation species" as early 1905 (Schaeffer Moreau 1958). process is frequency dependent, not only setting the ratio two species but driving community toward equilibrium. causes alternation, some probably related density regulation not, can all operate at size scale single large trees, excepting, course, dispersal. Trees themselves serve microhabitats for seedlings saplings, that sufficient mediating tree coexistence.