Vertical profiles and storage fluxes of CO2, heat and water in a tropical rainforest at Pasoh, Peninsular Malaysia

Ambient CO2 concentration, air temperature and relative humidity were measured intermittently for a 3-year period from the floor to the canopy top of a tropical rainforest in Pasoh, Peninsular Malaysia. Mean diurnal CO2 storage flux (S-c; mu mol m(-2) s(-1)) and sensible and latent heat storage fluxes (Q(a) and Q(w); W m(-2)) ranged from -12.7 to 3.2 mu mol m(-2) s(-1), - 15 to 27 W m(-2) and -10 to 20 W m(-2), respectively. Small differences in diurnal changes were observed in S, and Q,, between the driest and wettest periods. Compared with the ranges of mean diurnal CO2 eddy flux (- 14.7 to 4.9 mu mol m(-2) s(-1)), sensible eddy flux (-12 to 169 W m(-2)) and latent eddy flux (0 to 250 W m(-2)), the contribution of CO2 storage flux was especially large. Comparison with summertime data from a temperate Japanese cypress forest suggested a higher contribution of S-c in the tropical rainforest, probably mainly due to the difference in nighttime friction velocity at the sites. On the other hand, differences in Q(a) and Q(w) were smaller than the difference in S-c, probably because of the smaller nighttime sinks/sources of heat and water vapour.