Leaf and stem nutrient variation patterns and controls of Chenopodioideae plants along a desert transect in Central Asia.

Chenopodioideae plants are dominant components of desert ecosystems in arid regions of China and Central Asia and play key roles in maintaining ecosystem stability, while also providing valuable systems for understanding evolutionary and environmental adaptations of desert vegetation. However, at the family level, stoichiometric patterns across functional groups and plant organs in Chenopodioideae species remain poorly understood. We investigated 68 desert sites along a > 2000 km desert transect in northwestern China and collected leaf and stem samples from 39 Chenopodioideae species. After data preprocessing and standardization, 167 independent leaf units and 161 independent stem units were retained for subsequent analyses. We examined variation patterns and environmental drivers of nitrogen (N), phosphorus (P), and potassium (K) across functional groups (C3 vs. C4 plants; trees, shrubs, and herbs) and organs (stems and leaves) at the community level. Compared with global and national datasets, Chenopodioideae plants exhibited lower N concentrations (8.846 mg g− 1 in stems and 15.768 mg g− 1 in leaves) but higher P (1.235 mg g− 1 and 1.497 mg g− 1) and K concentrations (23.758 mg g− 1 and 27.656 mg g− 1), suggesting potential nitrogen limitation. Significant differences in nutrient concentrations were observed among most functional groups and organs. Based on community-weighted means, leaves exhibited consistently lower P-K scaling exponents than stems across functional groups, suggesting enhanced K-related stress resistance. Stem and leaf N, P, N: P, and P: K exhibited homeostatic or strictly homeostatic patterns, supporting the “Stability of Limiting Elements Hypothesis”. Nutrient traits showed divergent responses along latitude, longitude, and aridity gradients, reflecting diverse adaptive strategies. Environmental drivers varied among traits and organs. Soil, climatic, and geographical factors jointly regulated nutrient concentrations and ratios through interacting pathways, with soil factors generally exerting stronger relative influences. Overall, our findings reveal differentiated yet partially convergent stoichiometric strategies among functional groups and organs, highlighting adaptive nutrient regulation mechanisms in arid desert ecosystems.