%0 Generic %D 2004 %T Differential effects of nitrate and ammonium on three fen bryophyte species in relation to pollutant nitrogen input. %A Paulissen, M.P.C.P. %A van der Ven, P.J.M. %A Dees, A.J. %A Bobbink, R. %B New Phytologist %V 164 %P 451-458