Micrometeorology and assessment of primary production of a tropical rain forest in West Malaysia

The micrometeorology and the primary production of a lowland tropical rain forest at Pasoh, West Malaysia were studied. About 50% of incoming solar radiation was diminished by the upper 5m layer of canopy and only 3% reached the ground surface. The diurnal range of air temperature was small and humidity was higher than 90% throughout the day near ground. The upward water vapour transfer from the canopy to the atmosphere was observed even at night. This seemed to be related to the formation of night fog. Because the leaf area density of the forest was small, the gradients of air temperature, water vapour pressure, and carbon dioxide concentration in the forest were also small. The net canopy photosynthesis was about 43mgCO2⋅100cm-2·hr-1 when incoming solar radiation was 1.3cal·cm-2·min-1. The annual gross production of the forest was estimated at 81 ton D.W.·ha-1·year-1 and the efficiency of solar energy conversion for it was 3.0%.