Soil fluxes of mineral elements and dissolved organic matter following manipulation of leaf litter input in a Taiwan Chamaecyparis forest

Forest ecosystems in Taiwan are frequently influenced by typhoons that cause large amounts of litter input to the soil. The rapid decomposition
of such litter under the high precipitation and temperature conditions may trigger nutrient losses via seepage. Our goal was to investigate the effects
of exceptionally high inputs of Chamaecyparis obtusa var. formosana leaves to the soil on the solute fluxes and concentrations of mineral elements,
dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a Lithic Leptosol. We simulated the effect of a typhoon by adding the
annual aboveground litterfall (4600 kg ha_1) and about 3 times the annual litterfall (13,900 kg ha_1) as fresh leaves in a single event to small
manipulation plots. All plots were also subjected to the natural litterfall. Soil solution was collected 4 months before and 15 months following the
litter manipulation in 14 days intervals underneath the forest floor with free draining lysimeters and by ceramic suction cups at 60 cm depth. The 3-
fold litter addition caused increased fluxes of K, Mg, Ca, and NH4 in forest floor percolates as compared to the 1-fold litter treatment. DOC and
DON fluxes also increased, but this was only statistically significant for DON. DON was the dominant form of N both in forest floor percolates and
in seepage. The 3-fold litter manipulation increased the seepage fluxes of K, DON, and DOC relative to the 1-fold treatment with largest differences
recorded for K, reaching 12.4 kg ha_1 15 month_1. The fluxes of DOC with forest floor percolates and with seepage in both treatments exceeded
published values by far. Our results suggest that the decomposition of large amounts of fresh leaf litter may trigger K losses from the ecosystem via
seepage, whereas the probability for additional N and DOC losses is moderate. For Ca and Mg, additional losses seem to be rather unlikely.