Objective To elucidate the response mechanisms of soil phosphorus cycling in Phyllostachys edulis forests under climate change, this study implemented simulated throughfall reduction and nitrogen addition treatments. We systematically analyzed the impacts of soil chemical properties, enzyme activities, and their vector characteristics on phosphorus fraction transformations, aiming to establish a theoretical foundation for optimizing nutrient management and promoting sustainable silvicultural practices in Phyllostachys edulis ecosystems.

Method A field experiment was conducted in a subtropical Phyllostachys edulis plantation, implementing two treatments: throughfall reduction (50% exclusion) and nitrogen addition (100 kg/(ha·year)). Soil samples were collected and subjected to: Hedley phosphorus fractionation to quantify labile, moderately labile, and recalcitrant phosphorus pools; soil chemical characterization including pH, organic matter, and cation exchange capacity; 96-well fluorometric microplate assays to determine extracellular enzyme activities (acid phosphatase, β-glucosidase, N-acetylglucosaminidase) and their stoichiometric vectors.

Result (1) Throughfall reduction significantly decreased soil inorganic phosphorus (Resin-P, sonicated NaOH-Pi, Residual-P) and organic phosphorus fractions (NaOH-Po, HCl-Po), while markedly increasing sodium bicarbonate-extractable organic phosphorus (NaHCO₃-Po) content. (2) Nitrogen addition induced significant reductions in occluded-p but enhanced sodium bicarbonate-extractable inorganic phosphorus (NaHCO₃-Pi) concentrations. (3) Interactive effects between treatments showed no statistical significance on inorganic or organic P fractions except for NaHCO₃-Po. (4) Redundancy analysis (RDA) identified soil acid phosphatase (AP), leucine aminopeptidase (LAP) activities, and pH as key drivers of inorganic P variability, whereas soil moisture content primarily governed organic P fractionation patterns.

Conclusion The sensitivity of soil phosphorus fractions to throughfall reduction exceeds that to nitrogen addition in Phyllostachys edulis forests, with both drivers indirectly modulating phosphorus availability via enzymatic activity and pH regulation. Observed declines in acid phosphatase activity and shifts in enzyme stoichiometric vectors under experimental treatments indicate alleviation of microbial phosphorus limitation. To address climate change impacts, we propose prioritizing hydrological regulation in bamboo forest management while prudently evaluating the legacy effects of nitrogen deposition on soil phosphorus dynamics.