MINERAL NUTRIENT STATUS OF COASTAL HILL DIPTEROCARP FOREST AND ADINANDRA BELUKAR IN SINGAPORE - ANALYSIS OF SOIL, LEAVES AND LITTER

The soil of remnant primary rainforest on granite in Singapore is very acidic (pH mostly 3.5-4.2 at 0-10 cm) and has unusually low total con centration of nitrogen and phosphorus, but the mean concentrations of N and P in the living leaves and freshly fallen leaves of the more sha de-tolerant species are within the ranges found for other lowland fore sts on infertile oxisols and ultisols. The concentration of Ca in fres hly fallen leaves is very low. The soil under secondary forest (beluka r) on sandstone dominated by Adinandra dumosa (Theaceae) was degraded during use for agriculture. It has the same pH range but even lower va lues of total N and P. The mean concentrations of N, P, K, Ca and Mg i n the living leaves are slightly higher than in leaves of the more sha de-tolerant trees of primary forest, but lower than in the leaves of t he species which require canopy gaps for establishment or early onward growth. The few species sampled in both primary forest and belukar sh ow no consistent trend in foliar concentrations. The degraded soil has selected species with inherently lower foliar concentrations.