Phosphatase kinetics reveal mechanistic pathways of soil phosphorus recovery during long-term desert revegetation.

Phosphorus (P) limitation constrains dryland restoration, yet how phosphatase kinetics regulate soil P recovery remains unclear. We quantified P fractions and the activities and kinetic traits of alkaline phosphomonoesterase (PM), phosphodiesterase (PD), and inorganic pyrophosphatase (IP) across three desert restoration types: mobile dunes, a 31-year artificially revegetated desert, and natural vegetation in the Tengger Desert. Revegetation increased total, organic, and available P and enhanced PM and PD activities, substrate affinity, and catalytic efficiency, reflected by lower K m and K m /V max . Multivariate analyses showed that phosphatase kinetic traits explained 67.9% of the variation in P fractions. PM and PD were mainly associated with organic P mineralization, whereas IP kinetics were more closely linked to Ca-bound P fractions. These results reveal complementary phosphatase pathways regulating P turnover during desert revegetation and identify enzyme kinetic traits as potential process-based indicators of biochemical recovery in dryland restoration.