Acetylene reduction in soil and litter from pine and eucalypt forests in south-eastern Australia

Rates of C₂H₂-reduction in surface soil and litter from pine and eucalypt forests were measured for 1 yr. Rates of reduction increased significantly with moisture content, and mean rates (nmol kg^?1 h^?1) decreased in the order pine litter (339), eucalypt litter (220), eucalypt soil (54), pine soil (7). Asymbiotic N₂-fixation in litter and surface soil was estimated to be 108 mg m^?2 yr^?1 in eucalypt forest and 64 mg m^?2 yr^?1 in pine forest. About 80% of total fixation in eucalypt was in the soil, while 80% of the total in pine was in the litter. N₂ase was active in rotting wood but not in fresh foliage.