Linking root phosphatase activity to root chemical and morphological traits across species: a global analysis

Root phosphatase activity (RPA) is a key physiological trait that indicates plant phosphorus (P) acquisition ability, representing significant carbon investment and P gain. However, it is unclear how RPA is coordinated with key traits for nutrient acquisition. We analyzed a global dataset across 514 species from 83 studies to investigate how RPA is correlated with other key traits and its position within the global root economics space (RES) framework. We found that RPA exhibits significant coordination and trade-off with root morphological traits, yet remains independent of root branching and mycorrhizal colonization. Root nitrogen (N) and P concentrations were positively and negatively correlated with RPA, respectively. Moreover, we observed significantly higher RPA in N-fixers than in nonfixers, demonstrating the higher P-mining ability of N-fixers. Incorporating RPA into the classic RES, our findings support the multidimensional RES framework, showing a closer alignment of RPA with the acquisitive end of the conservation dimension. Our findings clarify how RPA is integrated into the global RES and contribute to an integrative understanding of plants' belowground strategies, with implications for plant form and ecosystem functioning.