Soil Phosphorus Dynamics and Enzymatic Activity Drive Understory Vegetation Successional Shifts in Foliar Phosphorus Limitation in Abandoned Moso Bamboo Forests

ABSTRACT Phosphorus (P) limitation is widespread in Moso bamboo ( Phyllostachys edulis ) forests and constrains growth and ecosystem functioning. Understanding how abandoned bamboo stands respond to changes in P availability during understory vegetation succession is critical for predicting ecosystem stability and informing sustainable management. We investigated abandoned Moso bamboo forests in southern Zhejiang Province, China, selecting sample plots representing early (0 years), mid (9 years), and late‐successional (21 years) stages to examine foliar P allocation and its relationships with soil P fractions, soil chemical properties, and phosphatase activities. The results showed that at 9 years, total foliar P decreased while the foliar N:P ratio increased, indicating severe P limitation; bamboo responded by increasing the content and proportion of metabolic P. By 21 years, total foliar P and foliar lipid P had recovered, and P limitation was substantially alleviated. Soil organic P fractions (NaHCO 3 ‐P o , NaOH‐P o , and C.HCl‐P o ) declined at 9 years but increased by 21 years, enhancing P bioavailability. Acidification and reduced phosphatase activities at 9 years constrained organic P mineralization, whereas elevated phosphatase activities at 21 years improved P availability. Partial least squares path modeling indicated that succession indirectly influenced foliar P allocation by modifying soil pH, total soil P, and phosphatase activity. Understory vegetation succession transformed abandoned bamboo stands from severe P limitation in the mid‐successional stage to alleviated limitation in the late stage, mediated primarily by shifts in soil P fractions and their bioavailability. These findings provide mechanistic insights into P cycling in bamboo‐dominated forests and inform strategies for restoring and sustainably managing degraded bamboo ecosystems.