In situ net mineralization rates in a heterogeneous mixed deciduous forest receiving elevated n deposition

In situ net mineralization was studied at 6 locations (E, Eb, Ec, F1, F2, F3) of a heterogeneous mixed deciduous forest ("De Gulkeputten") with oak (Quercus robur L., Quercus rubra) and birch (Betula pendula) as dominant species. Net nitrogen mineralization was determined by means of a sequential in situ incubation experiment using intact soil cores. For all incubations, the net mineralization rates of the organic (F+H) layer varied between -0.4 and 2.0 g N m(-2) month(-1), while the net nitrification rates varied between -0.6 and 0.7 g NO3- -N m(-2) month(-1). The net mineralization and nitrification rates of the mineral (0-30 cm) layer ranged from 4.5 g N m(-2) month(-1)to 8.8 g N m(-2) month(-1)and from -1.0 to 4.9 g NO3- -N m(-2) month(-1) respectively. In general, net mineralization rates increased from August 1998 to October 1998. Net mineralization rates were positively correlated with the gravimetrical moisture content and mineralization and nitrification rates were mutually positively correlated.