Foliar nutrient resorption stoichiometry and microbial phosphatase catalytic efficiency together alleviate the relative phosphorus limitation in forest ecosystems.

ABSTRACT

Understanding how plants adapt to spatially heterogeneous phosphorus (P) supply is important to elucidate the effect of environmental changes on ecosystem productivity. Plant P supply is concurrently controlled by plant internal conservation and external acquisition. However, it is unclear how climate, soil, and microbes influence the contributions and interactions of the internal and external pathways for plant P supply. Here, we measured P and nitrogen (N) resorption efficiency, litter and soil acid phosphatase (AP) catalytic parameters (Vmax(s) and Km ), and soil physicochemical properties at four sites spanning from cold temperate to tropical forests. We found that the relative P limitation to plants was generally higher in tropical forests than temperate forests, but varied greatly among species and within sites. In P-impoverished habitats, plants resorbed more P than N during litterfall to maintain their N  P stoichiometric balance. In addition, once ecosystems shifted from N-limited to P-limited, litter- and soil-specific AP catalytic efficiency (Vmax(s) /Km ) increased rapidly, thereby enhancing organic P mineralization. Our findings suggested that ecosystems develop a coupled aboveground-belowground strategy to maintain P supply and N  P stoichiometric balance under P-limitation. We also highlighted that N cycle moderates P cycles and together shape plant P acquisition in forest ecosystems.