Black spruce (Picea mariana)forests represent the dominant vegetation type throughout the North American and Siberian taiga and are generally considered ro be pristine, N-limiting environments. The aim of this sludy was to investigate the fundamental underlying mechanisms which control N availabil~ty in these soils with particuiar reference to the dynamics of dissolved organic nitrogen (DON)Our results showed that in these highly organic and low pH soils. soluble N is dominated by organic forms with correspondingly low concentrations of ammonium and nitrate. Amino acids, which are known to be directly taken up by plants growing in these soils, were calculated Lo constitute 10-20
A MINO ACIDS DISSOLVED ORGANIC NILLOGEN MICROBIAL KINETICS N MINERALIZATION N FLUX PERMAFROSL TAIGA ECOSYSTEMS