Effects of increased nitrogen deposition and rotation length on long-term productivity of Cunninghamia lanceolata plantation in southern China.

Effects of increased nitrogen deposition and rotation length on long-term productivity of Cunninghamia lanceolata plantation in southern China.

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Cunninghamia lanceolata (Lamb.) Hook.has been widely planted in subtropical China to meet increasing timber demands, leading to short-rotation practices that deplete soil nutrients.

However, increased nitrogen (N) deposition offsets soil N depletion.While long-term experimental data investigating the coupled effects related to short rotation practices and increasing N deposition are scarce, applying model simulations may yield insights.In this study, the CenW3.

1 model was validated and parameterized using data from pure C.lanceolata plantations.The model was then used to simulate various changes in long-term productivity.

Results indicated that responses of productivity of C.lanceolata plantation to increased N deposition were more related to stand age than laguna 3hp dust collector N addition, depending on the proportion and age of growing forests.Our results have also shown a rapid peak in growth and N dynamics.

The peak is reached sooner and is higher under higher level of N deposition.Short rotation lengths had a ice blue graphic tee greater effect on productivity and N dynamics than high N deposition levels.Productivity and N dynamics decreased as the rotation length decreased.

Total productivity levels suggest that a 30-year rotation length maximizes productivity at the 4.9 kg N ha(-1) year(-1) deposition level.For a specific rotation length, higher N deposition levels resulted in greater overall ecosystem C and N storage, but this positive correlation tendency gradually slowed down with increasing N deposition levels.

More pronounced differences in N deposition levels occurred as rotation length decreased.To sustain C.lanceolata plantation productivity without offsite detrimental N effects, the appropriate rotation length is about 20-30 years for N deposition levels below 50 kg N ha(-1) year(-1) and about 15-20 years for N deposition levels above 50 kg N ha(-1) year(-1).

These results highlight the importance of assessing N effects on carbon management and the long-term productivity of forest ecosystems.