In Decalepis hamiltonii, extended flowering pattern, self-incompatibility, pollinator limitation, absence of seed dormancy, abortion of a considerable percentage of seedlings prior to establishment are contributing factors for the regulation of its population size. Further, the roots of this plant are over-exploited due to its commercial value in the preparation of a soft drink "nannari sharbat" in India. In Shorea tumbuggaia, non-annual flowering, massive flowering, short flowering period, partial flowering at tree level, seed predation, absence of seed dormancy and inability of seedlings to compete with other simultaneously growing plants for establishment collectively contribute to the existence of small population size of S. tumbuggaia in a restricted area of Eastern Ghats forests in India.