Data and code for: Global patterns of nitrogen saturation in forests

Since the industrial revolution, accelerated atmospheric nitrogen (N) deposition by human activities have increased N availability in forest ecosystems close to human settlements, potentially causing nitrogen-limited forests to become nitrogen-saturated. In N-saturated forests, oversupply of N leads to higher N losses as compared to N-limited forests, suggesting that the sensitivity of soil N2O emission to N deposition (sN) might indicate N saturation. In this study, we modeled the sN of global forests using N addition experimental data. Testing with previous field observations of N-saturated forests, the global patterns of N-limited and N-saturated forests indicated by sN show an accuracy above 80% on global and geographic-regional scales. Our results suggest that 47.5% of global forests are N-saturated. The produced global map of N-saturated forests reveals the spatially varying N status of forests, which is useful for predicting forest greenhouse gas emissions and productivity, facilitating optimized environmental management practices for different regions.