Tropical secondary forest are becoming increasingly common in the last few decades following high rates of deforestation. There are few long-term studies in Southeast Asia that track secondary forest recovery. Original vegetation in Singapore have been exposed to disturbances for the past two centuries, and secondary forests form the majority of forest cover in the country. Therefore the secondary forests of Singapore are ideal for studying long-term recovery, its trajectory and dynamics. We monitored a 2-ha secondary forest plot in Bukit Timah Nature Reserve, Singapore, over 3 surveys spanning 8 years.
Although the total number of trees in the plot remained fairly constant throughout the 8 years, the abundance of primary forest and generalist species increased, while that for secondary forest species decreased. 18 new primary forest species and 4 new generalist species recruited inside the plot. Basal area and basal area increment of generalist species were the highest, followed by primary forest species. Three out of the four dominant species in the plot had declining populations. There were no density-dependent mortality of the dominant species except for Campnosperma auriculatum, of which it occurred between 2-11 m. The soils in the secondary forest were not different from the adjacent primary forest except that soil carbon was higher and phosphorus was lower in the secondary forest. After >60 years of land abandonment following agriculture and fire, this secondary forest appears to be restarting regeneration once again.