Hydrobiogeochemistry of a Hill-Evergreen Forest in Northern Thailand.

Abstract

Studies on hydrobiogeochemistry were carried out in a hill-evergreen forest in northern Thailand. In this study forest climate conditions are characterized by a clear seasonal pattern of precipitation with dry and rainy season. Chemical properties of precipitation, throughfall and drainage waters were measured from December 1993 through February 1995. During the study period, annual precipitation was 2184 mm in the rainy season from March to October. Annual throughfall was 2936 mm. Higher throughfall would be attributed to fog interception by the canopy. Elemental fluxes in bulk precipitation and throughfall were high in the early rainy season from March to May. Elemental concentrations in forest drainage water of this watershed were in the lower range of concentration reported in other studies for tropical forests. Especially, Ca2+,Mg2+, Cl- and NO3- were very low concenfiations. For SO42-, NO3-, NIH4+ and Si concentrations in drainage water declined in the rainy season and increased during the dry season. These results suggest the minimum element losses from this tropical watershed.