Root phosphatase aligns with the collaboration gradient of the root economics space.

● Adopting diverse resource acquisition strategies is critical for plant growth and species coexistence. Root phosphatase is of particular importance in acquiring soil phosphorus (P), yet often overlooked in root traits syndrome. ● Here, we evaluated the role of root phosphatase activity (RPA) within the root economics space and the order-based variation of RPA, as well as the correlations of RPA with a suite of leaf traits and soil properties over a range of evergreen tree species in a subtropical forest. ● Root phosphatase exhibited a large inter-specific variation. We found there were two leading dimensions of the multi-dimensional root economics space, i.e. root diameter [RD]-specific root length [SRL] axis (collaboration trait gradient) vs. root tissue density [RTD]-root nitrogen concentration [RNC] axis (classical trait gradient), and RPA aligned with the former. Root phosphatase is a strategy of "do it yourself" in acquiring soil P, and it correlated inversely with mycorrhizal colonization which suggests a trade-off in plant P acquisition strategies. Compared with soil and foliar nutrient status, root traits mattered more for the large inter-specific changes in RPA. Furthermore, RPA generally decreased from the first to the third order roots. ● Taken together, such diverse P-acquisition strategies are conducive to plant coexistence within local forest community. Easily measurable root traits and their tight correlations with RPA could be a feasible and promising approach to estimate species-specific RPA, which is helpful for better understanding plant P acquisition and soil P cycling.