TY - JOUR
T1 - Bidirectional ammonia exchange above a mixed coniferous forest
AU - Neirynck, Johan
AU - Ceulemans, R
N1 - Publication Authorstring : Neirynck , J.; Ceulemans, R.
Publication RefStringPartII : <i>Environmental Pollution 154(3)</i>: 424-438
PY - 2008
Y1 - 2008
N2 - Two canopy compensation point models were used to study the bidirectional exchange of ammonia over a mixed coniferous forest subjected to high nitrogen deposition. The models were tested for 16 time series, average fluxes of which ranged between -270 and +1 ngm-2s-1. The static model consisted of a bidirectional stomatal flux and a unidirectional cuticular flux component. The dynamic model also allowed for desorption of ammonia from the leaf surface and took into account ammonia fluxes from precedent periods. The apoplastic ammonium/hydrogen ion ratio (Γ), which was derived to estimate the stomatal compensation point (Χs), amounted to 3300 in spring and 1375 during the summer/autumn. Empirical descriptions for cuticular resistances (Rw) in the static model, developed as a function of micrometeorological conditions and codeposition effects, failed to reproduce the measured fluxes. A better match with measurements was obtained using the dynamic model, which succeeded in simulating net-emission during the daytime.
AB - Two canopy compensation point models were used to study the bidirectional exchange of ammonia over a mixed coniferous forest subjected to high nitrogen deposition. The models were tested for 16 time series, average fluxes of which ranged between -270 and +1 ngm-2s-1. The static model consisted of a bidirectional stomatal flux and a unidirectional cuticular flux component. The dynamic model also allowed for desorption of ammonia from the leaf surface and took into account ammonia fluxes from precedent periods. The apoplastic ammonium/hydrogen ion ratio (Γ), which was derived to estimate the stomatal compensation point (Χs), amounted to 3300 in spring and 1375 during the summer/autumn. Empirical descriptions for cuticular resistances (Rw) in the static model, developed as a function of micrometeorological conditions and codeposition effects, failed to reproduce the measured fluxes. A better match with measurements was obtained using the dynamic model, which succeeded in simulating net-emission during the daytime.
U2 - 10.1016/j.envpol.2007.11.030
DO - 10.1016/j.envpol.2007.11.030
M3 - A1: Web of Science-article
VL - 154
SP - 424
EP - 438
JO - Environmental Pollution
JF - Environmental Pollution
IS - 3
ER -