The capacity of forest soil to absorb anthropogenic N

Knowledge of the N accumulation rate in soil is crucial for the calculation of "critical loads" of N in forest ecosystems. Calculations of an average rate is based on an assumed constant rate of N accumulation, which may not be correct. In the present study, variations in N accumulation in forest so il due to i) stand age; and ii)N deposition have been investigated. An incr ease in total amount of N in the mor layer with increasing forest stand age was observed, indicating a constant N accumulation rate of approximately 0 .16 g N m(-2) yr(-1) in this layer. However, the data showed that the total accumulation of N in the soil down to about 70 cm may vary during the fore st succession. No significant effect of increased N deposition on the total amount of N was observed. Most of the extra N applied seemed to be taken u p by the plants.