Nitrogen Accumulation and Contribution of Biological Nitrogen Fixation in a Waste Forest

Abstract

Nitrogen fixation activity (ARA) in a wasted forest was determined by using th acetylene reduction technique. In the investigated plot, 62% of the ground surface was covered by vegetation, but 38% of that was bared. In the vegetation covered area, about 75% of total nitrogen and 98% of above ground nitrogen was accumulated respectively. While 0.94 kg·m^-2 of litter was accumulated, ARA of that was lower in vegetation covered area. As a compare with that, the significant ARA of blue-green algae occurred in the surface soil of bared area.
Total nitrogen fixation was estimated to be 215.43 mgN₂·80 m^-2·day^-1 in the investigated plot with the theoretical conversion ratio 3: 1, and about 89% of total fixation was in bare area. The recovery of ARA after re-watered of air-dried (below 5% of moisture content based on dry matter) surface soil was investigated. It was recognized the recovery of ARA was started about 8-hrs after re-watered in algaes and lichen.