Data from: Leaf C:P ratio as a universal indicator of photosynthesis in subtropical woody species: Stoichiometric thresholds and metabolic trade-offs

The stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P)
serve as important indicators for assessing nutrient balance in forest
ecosystems, but their relationships with photosynthetic dynamics require
deeper characterization. This study systematically examined the
associations between leaf C-N-P stoichiometry and photosynthetic traits
across 92 dominant woody species in subtropical regions. We found that the
C:P ratio exhibited unique evolutionary flexibility compared to other
elemental ratios, showing its environmental plasticity. Among all
stoichiometric parameters, leaf C:P displayed the strongest correlation
with maximum net photosynthetic rate (Amax), closely linked with its
coordinated variations in stomatal conductance, chlorophyll content, and
specific leaf area. In-depth metabolic analysis of 31 representative
species revealed that leaf C:P ratio effectively captured two critical
processes: (1) the accumulation patterns of photosynthetic products, and
(2) the metabolic P allocation regulated by acid phosphatase activity.
This dual sensitivity enabled C:P to serve as a synthetic indicator
reflecting both carbon assimilation efficiency and phosphorus metabolic
status. In contrast, N:P ratio showed limited predictive value for Amax
due to its inability to integrate the co-variation of photosynthetic
product dynamics and nutrient regulation. Our findings establish leaf C:P
ratio as a robust bioindicator for evaluating photosynthetic performance
in subtropical forests. This metric not only enhances our capacity to
monitor carbon sink potential but also provides critical insights for
optimizing phosphorus management strategies in artificial afforestation
programs.