Plant nitrogen uptake preference and drivers in natural ecosystems at the global scale

Summary

Elucidating plant nitrogen (N) acquisition is crucial for understanding plant N strategies and ecosystem productivity. However, the variation in plant N uptake preference and its controlling factors on a global scale remain unclear. We conducted a global synthesis to explore plant N preference patterns and driving factors. Globally, the average contributions of ammonium (NH₄ ⁺), nitrate (NO₃ ^-), and glycine N to the total plant N uptake were 41.6 ± 1.1%, 32.8 ± 1.2%, and 25.6 ± 0.9%, respectively. However, plant N uptake preferences differed significantly among climatic regions and vegetation types. Soil NH₄ ⁺ was the most preferred N form by plants in (sub)tropical regions, whereas NO₃ ^- preference was