Data from: Patterns and drivers of atmospheric nitrogen deposition retention in global forests

<p>Forests are the largest carbon sink in terrestrial ecosystems, and the impact of nitrogen (N) deposition on this carbon sink depends on the fate of external N inputs. However, the patterns and driving factors of N retention in different forest compartments remain elusive. In this study, we synthesized 408 observations from global forest ¹⁵N tracer experiments to reveal the variation and underlying mechanisms of ¹⁵N retention in plants and soils. The results showed that the average total ecosystem ¹⁵N retention in global forests was 63.04 ± 1.23%, with the soil pool being the main N sink (45.76 ± 1.29%). Plants absorbed 17.28 ± 0.83% of ¹⁵N, with more allocated to leaves (5.83 ± 0.63%) and roots (5.84 ± 0.44%). In subtropical and tropical forests, ¹⁵N was mainly absorbed by plants and mineral soils, while the organic soil layer in temperate forests retained more ¹⁵N. Additionally, forests retained more ¹⁵NH₄⁺ than ¹⁵NO₃⁻, primarily due to the stronger capacity of the organic soil layer to retain ¹⁵NH₄⁺. The mechanisms of ¹⁵N retention varied among ecosystem compartments, with total ecosystem ¹⁵N retention affected by N deposition. Plant ¹⁵N retention was influenced by vegetative and microbial nutrient demands, while soil ¹⁵N retention was regulated by climate factors and soil nutrient supply. Overall, this study emphasizes the importance of climate and nutrient supply and demand in regulating forest N retention and provides data to further explore the impacts of N deposition on forest carbon sequestration.</p>