Nutrient Status and Fluxes at the Field and Catchment Scale

Rainfall, litter fall, and organic matter turnover are the major drivers of nutrient fluxes in forest ecosystems. During its passage through the forest, the quantity and chemical composition of water — which enters the forest via rainfall and clouds — changes (Parker 1983). The chemical quality of throughfall and stemflow is controlled by the intensity of rainfall, dry deposition, and soil fertility (Parker 1983; Schaefer and Reiners 1990). The few studies on litter leachate, i.e. the water percolating through the organic layer, in tropical forests indicate that the concentrations of all nutrients increase compared with rainfall and throughfall (e.g., Steinhardt 1979; Hafkenscheid 2000; Wilcke et al. 2001a). In stream water, nutrient concentrations are lower than in litter leachates, except for elements which are released by weathering (Bruijnzeel et al. 1993; McDowell 1998).