TREE SPECIES RICHNESS IN PRIMARY AND OLD SECONDARY TROPICAL FOREST INSINGAPORE

If secondary succession can accumulate species rapidly, then tropical secondary forests may have an important role to play in the conservati on of biodiversity. Data on the floristic composition of forest stands in the Central Catchment Nature Reserve, Singapore, have been analyse d to investigate the diversity of approximately 100-year-old tropical secondary forest. Classification using TWINSPAN indicated that three f loristic communities could be recognized from 59 0.2 ha plots enumerat ed for trees > 30 cm gbh. These were two types of secondary forest, bo th dominated by Rhodamnia cinerea (Myrtaceae), and dryland primary for est. The secondary forest was developed on land abandoned after use fo r agriculture at the end of the 19th century. The 16 primary forest pl ots contained a total of 340 species, more than the 281 recorded from the 43 plots of the two secondary forest types combined. The mean spec ies number per plot in the more diverse of the two secondary forests w as only about 60% of the primary forest. Thus the secondary forest, de spite a century or so for colonization by species and the presence of contiguous primary forest, was still significantly less diverse than p rimary forest areas. It is concluded that secondary forest cannot be a ssumed to accrete biodiversity rapidly in the tropics, and may not be of direct value in conservation. However, other indirect roles, such a s providing resources for native animals, and buffering and protecting primary forest fragments may make the protection of secondary forest worthwhile.