A comparison of dinitrogen fixation rates in wood litter decayed by white-rot and brown-rot fungi

Nitrogen fixation rates, as estimated by the acetylene reduction technique, were determined in conifer wood litter being decayed by brown-and white-rot fungi. Average ethylene production rates were significantly higher in white-rotted wood (15.1 nmol g⁻¹ day⁻¹) than in brown-rotted wood (2.3 nmol g⁻¹ day⁻¹). This difference may be related to a higher soluble sugar content in white-versus brown-rotted wood. The nitrogen-fixing bacterium Azospirillum was not detected in any of the decaying wood samples examined. Greater nitrogen additions from nitrogen-fixing bacteria may be a factor in the more rapid white-rot decay of hardwood litter, as compared to the slower brown-rot decay of conifer wood.