Soil nitrogen (N) is crucial for sustaining ecosystem processes and functions, and plants play a significant role in influencing soil N availability and transformation processes. Yet, even as biodiversity declines, our understanding of how plant diversity impacts soil N cycling is limited, making it difficult to predict terrestrial N pools and transformations globally.

To address this knowledge gap, researchers from the Wuhan Botanical Garden of the Chinese Academy of Sciences undertook a global meta-analysis. They synthesized data from paired observations of plant mixtures and corresponding monocultures to assess how plant diversity affects soil N pools and N transformations over the long-term.

The analysis revealed that plant mixtures strongly influence soil N pools and dynamics, with the effects on total N and on N transformation rates (mineralization, nitrification, and denitrification) shifting from negative to positive over time. However, their impacts on soil nitrate (NO₃^-) - N content and N₂O emissions remain consistently negative.

These findings suggest that maintaining plant diversity can contribute to long-term sustainability in soil N cycling and potentially mitigate climate change-related risks by reducing N₂O emissions. 

The researchers note that long-term observations remain essential for fully understanding the complex interactions between plant diversity and soil nutrient dynamics.

This study was funded by the National Natural Science Foundation of China and the results were published in Journal of Applied Ecology on February 15.