The stoichiometric traits and biogeochemical niches of four alpine herbs along elevation gradient in southeastern Tibet

Ecological stoichiometry is a fundamental concept for understanding nutrient allocation strategies and ecosystem functioning. However, the spatial and elevational variability of stoichiometric traits across different plant species and their organs remains poorly understood, particularly in high-altitude ecosystems. This study systematically investigated the C:N:P ecological stoichiometry of four alpine herbaceous species- Potentilla saundersiana , Carex moorcroftii , Kobresia humilis , and Leontopodium leontopodioides —across an elevation gradient ranging from 2,647 to 4,898 meters in the alpine grasslands of southeastern Tibet. A total of 433 samples were collected from 34 distinct sites to assess the influence of elevation gradient on plant stoichiometry. Our results revealed significant intra- and interspecific variations in stoichiometric traits among organs and species. Carex moorcroftii exhibited the largest biogeochemical niche size, while L . leontopodioides showed the smallest. Leaves generally exhibiting higher biogeochemical niche size than stems and roots. Elevation significantly influenced plant nitrogen and phosphorus concentrations, with species-specific responses. Climatic factors explained most of the variance in carbon-related stoichiometric traits, while soil nutrients primarily affected phosphorus-related traits. These results highlight the complex interactions among climatic, soil, and biological factors in shaping plant stoichiometry along elevation gradients. This study confirms the intraspecific and interspecific variations in plant stoichiometry and altitudinal heterogeneity in alpine grassland ecosystem, offering valuable insights for future ecological modeling and conservation efforts.