Effect of Simulated N Deposition on Soil Exchangeable Cations in Three Forest Types of Subtropical China∗1

The effects of simulated nitrogen (N) deposition on soil exchangeable cations were studied in three forest types of subtropical China. Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest): control (0 kg N ha−1 year−1), low N (50 kg N ha−1 year−1), medium N (100 kg N ha−1 year−1) and high N (150 kg N ha−1 year−1), and only three treatments (i.e., control, low N, medium N) were established for the pine and mixed forests. Nitrogen had been applied continuously for 26 months before the measurement. The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests, and exhibited some significant negative symptoms, e.g., soil acidification, Al mobilization and leaching of base cations from soil. The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations. Response of soil exchangeable cations to N deposition varied in the forests of subtropical China, depending on soil N status and land-use history. Key Words: exchangeable cation, forest soil, land-use history, N deposition, subtropic