PLANT SUCCESSION ON DEGRADED LAND IN SINGAPORE

Abstract

The course of secondary succession on land degraded by prolonged cultivation is described. On the most degraded sites, the pioneer vascular flora consists of only 13 non-parasitic species and is independent of the proximity of forest seed sources. This pioneer community is replaced after 20 to 50 y by a secondary forest with 35 to 64 species > 2 cm dbh in a 0.1 ha plot (more species-rich than any extra-tropical forest), dominated by the families Guttiferae, Myrtaceae, Elaeocarpaceae, and Lauraceae. After 50 to 100 y this forest still contains no Dipterocarpaceae or other poorlydispersed members of the local rain forest flora. This study suggests that plant succession on degraded land is initially controlled by edaphic factors - nutrient deficiency or periodic water stress - and later by seed dispersal.