The hidden cost of coloration of red leaf: Anthocyanin accumulation drives carbon and potassium accretion at the expense of nutrient resorption

While the photoprotection hypothesis posits that anthocyanin accumulation facilitates nitrogen (N) and phosphorus (P) resorption during leaf senescence, the hidden stoichiometric costs of this defensive investment remain poorly understood. We sampled leaves across continuous seven-stage color gradients (spanning from pure green to deep red and yellow) within individual Liquidambar formosana canopies to disentangle the stoichiometric and physiological divergence between red and yellow senescence trajectories. The yellow trajectory aligned with the classical paradigm, showing synchronized chlorophyll degradation and proficient resorption of N (decreasing from 12.9 mg g –1 to 9.13 mg g –1 ) and P (decreasing from 4.59 mg g –1 to 3.36 mg g –1 ). In contrast, the red trajectory functioned as a metabolic sink, characterized by the substantial accretion of carbon (C) and potassium (K) and the suppression withdrawal of N and P. We propose that the accretion of K likely provides the necessary osmotic support associated with vacuolar anthocyanin storage, while the retention of N points to a metabolic conflict, potentially resulting from transient investments in active defensive pathways alongside other physiological bottlenecks. Rather than viewing anthocyanin accumulation solely through the narrow lens of nutrient resorption protection, our findings highlight the multifunctionality of these pigments. Recognizing these divergent senescence strategies is crucial for managing soil nutrient budgets in both commercial forests and urban landscapes, particularly as climate change potentially alters autumn coloration.