Nitrification and nitrogen accumulation in the early stages of primary succession on Mt. Fuji

Abstract

AbstractThe relationship between nitrification potential and nitrogen accumulation was studied in an early successional sere on Mt. Fuji. Soil organic nitrogen accumulated with the invasion of Polygonum cuspidatum and successively with Miscanthus oligostachyus and other species. Laboratory incubation experiments showed a higher nitrification potential at the M. oligostachyus state. The numbers of nitrifying bacteria increased with the progress of succession. No significant difference in nitrate reductase activity was found between pioneer and succeeding species. The soil solution at the M. oligostachyus stage contained a lower level of nitrate than rainwater, while that of the bare ground and the P. cuspidatum stage contained a higher nitrate level than rainwater. It was concluded that the high nitrate levels in the soil solution of the bare ground and the P. cuspidatum stage were due to lower nitrate‐absorbing activity, leading to loss of nitrogen with precipitation, while the lower nitrate levels at the M. oligostachyus stage when higher nitrification activity occurred were due to higher nitrate‐absorbing activity, preventing net loss of nitrogen from the ecosystem.