Database of nitrogen deposition critical loads for herbaceous plants under forests with different mycorrhizal types (V1.0)

Abstract Objective Nitrogen deposition is a key driver shaping the structure and function of global forest ecosystems. When nitrogen deposition exceeds its critical load (CL), it induces significant alterations in the diversity and abundance of understory herbaceous plants. As a pivotal biological regulatory factor in forest ecosystems, mycorrhizal type profoundly modifies the response patterns of herbaceous plants to nitrogen deposition by regulating soil nutrient cycling and plant nitrogen acquisition strategies. However, a database that systematically integrates mycorrhizal types with the nitrogen deposition critical loads of herbaceous plants is currently lacking. Method Based on published literature, the global nitrogen deposition critical load database (e.g., Wilkins’ database), and relevant supplementary datasets, this study constructed the “Database of Nitrogen Deposition Critical Loads for Herbaceous Plants Under Forests with Different Mycorrhizal Types (V1.0)”. This database contains 3592 records, including information on herbaceous plant species, functional groups, mycorrhizal types, critical load values (and their uncertainty ranges) calculated using the TITAN method, environmental factors, and data reliability indicators. Result Significant differences in critical loads were observed for herbaceous plants under forests with distinct mycorrhizal types: the critical load was the highest in AM+ECM forests, followed by ECM forests, and the lowest in AM forests. Conclusion This database is of great significance for deciphering the mycorrhizal type-mediated nitrogen response mechanisms of herbaceous plants, assessing nitrogen deposition risks, and formulating regional ecological management strategies.