Water chemistry and temporal variation of nutrients in stemflow of three dominant tree species in the subtropics of the Fu-shan forest

The chemistry of stemflow for the forests at Fu-shan site has not been studied. The objective of this study was to compare stemflow of three dominant tree species in a subtropical rain forest of northeastern (NE) Taiwan. The three dominant tree species were yellow basket-willow (Engelhardtia roxburghiana), Morris persimmon (Diospyros morrisiana) and Chinese cryptocarya (Cryptocarya chinensis). Stemflow from yellow basket-willow had the highest pH and concentration of cations and anions. In general, mean concentrations of NH sub(4) super(+) and NO sub(3) super(-) in stemflow were lower than those in precipitation, reflecting uptake processes in vegetation. On the other hand, stemflow was greatly enriched with SO sub(4) super(2-). We believe this is due to dry deposition rather than from leached metabolites. There are no clear temporal patterns for most of the ions observed in stemflow chemistry. Stemflow was greatly enriched in K super(+) concentrations during growth season from April to May of 1991 and 1992.