Organ-specific and stage-dependent aboveground stoichiometric economics in Fargesia denudata

Plant stoichiometric traits can indicate nutrient allocation and resource-use strategies, but their interpretation depends on organ identity and developmental stage. Fargesia denudata is a staple bamboo for giant pandas and an important clonal understory plant in subalpine forests. We examined how C, N, and P concentrations and their ratios are coordinated across aboveground organs and ontogeny, and how stage-specific stoichiometric economics is associated with environmental and community variables.

Across 52 plots in Wanglang National Nature Reserve, including 37 plots with F. denudata, we measured stoichiometric traits in shoot culms and in mature culms, leaves, and twigs, together with topographic, soil, and community variables.

Stoichiometric coordination was modular and stage-specific, with limited independent within-organ coordination retained only in shoot culms and mature twigs, and cross-organ links suggesting that mature twigs acted as the main bridge between culms and leaves. PC1 axes generally separated N- and P-enriched stoichiometry from ratio-enriched stoichiometry, indicating comparable but developmentally reorganized stoichiometric-economic axes. Shoot culms occupied the nutrient-enriched, relatively acquisitive end of the axis, whereas mature culms shifted toward the ratio-enriched, more conservative end. Shoot-culm PC1 did not scale significantly into mature organ-level or integrated mature aboveground PC1, indicating developmental reorganization rather than direct continuity. In mature bamboo, aboveground stoichiometric economics was assembled through organ-specific contributions, with twigs forming the main link between culms and leaves. Plots with F. denudata occurred on steeper slopes and had higher soil C concentration than plots without F. denudata. Environmental and community associations were stage-dependent and were concentrated mainly in shoot culms. Elevation showed a significant positive total effect on shoot-culm PC1, corresponding to a shift toward a more conservative stoichiometric strategy along the elevational gradient. Mature aboveground PC1 showed a more limited pattern, with only a single correlation with soil pH.

These results suggest that stoichiometric strategies in F. denudata are shaped by organ-specific coordination, ontogenetic reorganization, and stage-dependent links with environmental and community conditions. Organ- and stage-specific stoichiometric indicators may inform bamboo resource assessment and giant panda habitat evaluation.