Biological traits are correlated with elevational distribution range of eastern Tibetan herbaceous species

Plants that share the same habitat often exhibit similar biological traits. As climatic conditions change with increasing elevation, biological traits are expected to vary among plant species with temperate endemic, alpine endemic, or widespread elevational distributions. On a northeast Tibetan flora including temperate (1,850–2,800 m a.s.l.), subalpine (2,800–3,400 m a.s.l.), and alpine (3,400–4,150 m a.s.l.) vegetations, we analyzed patterns of change for ten traits of 326 annual and perennial herbaceous species using both univariate and multivariate analyses. The traits selected for this study fit in different groups, i.e., traits related to light competition, photosynthesis, reproduction, defense, and dispersal. We found that plant shape (plant height and leaf distribution along stem) and leaf traits (specific leaf area and leaf area) were significant predictors of plants’ elevational distributions, suggesting an important role for a trade-off between light competition and biomass costs in support structures, and between photosynthetic efficiency and leaf defense. Moreover, species with a broad distribution had significantly higher seed germination and shorter first germination time, as compared to species with narrow distributions, which indicates that rapid regeneration may be crucial for widespread species. However, dispersal-related traits may not be the main factor in shaping plants’ elevational distribution because no significant difference was detected in wind- and animal-dispersal ability. In addition, annual species potentially may have different strategies and adaptive mechanisms because we detected no differences in trait related to the elevational distributions.