Abstract
Recent evidence from nitrogen (N) saturation studies indicates that forest floors in moderately impacted forests are the primary sink for atmospheric N inputs. Some researchers have suggested that the sink capacity of organic horizons is dependent on the amount of available carbon (C), which can be used for microbial N assimilation. To test the hypothesis that C limitation in forest floors exposed to chronic N deposition leads to an enhanced N leaching, a field C input manipulation experiment is under way in a deciduous forest. Since September 1999 aboveground C input has been doubled (by doubling litter input or by amending glucose) or excluded in replicated plots. Here we report the short-term response of concentrations of dissolved inorganic N (DIN: NO3--N and NH4+-N) in forest floor percolate to the C input manipulation. In autumn following the C input manipulation, DIN concentrations in forest floor percolate decreased in all plots except the No Litter plots compared to the pre-treatment summer concentrations. In contrast, the concentrations of DIN in the No Litter plots remained high. A different seasonal pattern of DIN leaching among treatments, along with measurements of microbial biomass C and potential nitrification rates of forest floor samples, indicates that seasonal N dynamics in the forest floor are largely regulated by C availability changes associated with litterfall C input.
Original language | English |
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Pages (from-to) | 643-648 |
Number of pages | 6 |
Journal | Water, Air, and Soil Pollution |
Volume | 130 |
Issue number | 1-4 II |
DOIs | |
State | Published - 2001 |
Keywords
- C control on N dynamics
- C input manipulation
- C limitation
- Dissolved inorganic N (DIN)
- Forest floor
- N saturation
- Nitrate leaching