The static view of old-growth forests have now been replaced by more dynamic models of constant change. Species abundances change with inherent demographic growth rates, or with environmental fluctuations. We examined species abundance changes of tree species within a 2-ha plot in Bukit Timah, Singapore. We hypothesize that pioneer species will become more abundant at the expense of shade-tolerant species, due to the two droughts that occurred during the series of surveys. We also hypothesize that light-demanding non-pioneer species will increase in abundance. Overall, 95 species increased in abundance significantly, while 74 species decreased in abundance significantly. The abundance of only 3 out of 8 pioneer species increased significantly over 19 years, while the abundance of 3 out of 7 light-demanding non-pioneer species increased significantly. One of these species, Shorea curtisii, is the most dominant canopy species in Bukit Timah. S. curtisii also had very high growth rates in every survey interval, even during droughts. Abundance ranks changed for 7 of the top 10 species, but changes were also prevalent for all the other species. We also examine relationships of abundance changes with mortality and growth rates.