Nitrogen deposition and tree canopy influence on soil C-CO2 efflux

Abstract

The increase in atmospheric nitrogen deposition over the years can affect biogeochemical cycling through the action of soil microbiota. The objective of this study was to evaluate the influence of N deposition beyond the tree canopy areas on soil C-CO₂ efflux. Four tree species were selected in the open field. For each species, three individuals were selected and the efflux of C-CO₂ from the soil under their canopies was evaluated with and without the presence of ammonium nitrate (NH₄NO₃). They were compared with grass areas (Paspalum notatum Flüggé). The addition of NH₄NO₃ induced changes in the slope of the straight lines describing the soil C-CO₂ efflux to areas under (105%) and outside the trees canopies (70%). The area under Inga laurina canopy was the only one with lower C-CO₂ efflux. We concluded that Inorganic N deposition in the state of Rio de Janeiro (9.6 kg N ha^-1), intensifies the C-CO₂ efflux in the soil and that tree species with bigger canopy areas such as I. laurina provide a reduction of this efflux.