NUTRIENT LIMITATION OF SEEDLING GROWTH ON contrastin G SOILS FROM PASOH FOREST RESERVE, PENINSULAR MALAYSIA

A pot bioassay experiment was established to test the hypotheses that different soil types represented on a 50 ha plot in Pasoh Forest Reserve supply different amounts of nutrients for plant growth, and that phosphorus (P) is the main limiting nutrient. Seedlings of the tree Lagerstroemia floribunda were grown for 54 days in pots of alluvial, shale or laterised-shale soil. The experiment comprised six nutrient addition treatments and an unmanipulated control, with five replicates for each treatment. The growth of seedlings of L. floribunda was limited by the availability of P but not by the other nutrients (N, K, Ca or Mg) added singly in the experiment. Relative growth rates were highest on alluvial and shale-derived soils, which had higher available P concentrations than the laterised shalederived soils in the absence of nutrient addition. Shifts in biomass allocation and changes to specific leaf area were the mechanisms responsible for the increase in plant growth in response to nutrient addition.