Effect of geographical range size on plant functional traits and the relationships between plant, soil and climate

Aim Our aim was to address the potential effect of the geographical range size of species on the relationships between plant traits, soil and climate in Chinese grasslands. Previous analyses tended to examine plant–environment relationships across many species while ignoring that species with different range sizes may respond differently to the environment. Here we hypothesized that leaf traits of narrow-ranging species would be more strongly correlated with soil and climatic variables than those of wide-ranging species. Location Chinese grasslands. Methods Data on leaf traits, including nitrogen and phosphorus concentrations, carbon/nitrogen ratio, nitrogen/phosphorus ratio and specific leaf area, as well as species range sizes for 208 species distributed across 178 sites in Chinese grasslands were collected. Soil and climate information for each study site was also gathered. The effects of range size on leaf traits were tested using one-way ANOVA. Correlations between leaf traits, soil and climate were calculated for all species pooled together and for species partitioned into range size quartiles, from the first (narrowest- ranging 25%) to the fourth (widest-ranging 25%). Results Narrow-ranging species tended to occur at high altitude with lower temperature but higher soil nutrient concentrations compared with wide-ranging species. No direct link between leaf traits and species range sizes was detected. However, patterns of leaf–soil nutrient relationships changed significantly across levels of range size. Narrow-ranging species tended to be more sensitive to variation in soil nutrient availability than wide-ranging species, resulting in a shift from a positive leaf–soil nutrient relationship for narrow-ranging plants to no relationship for wide-ranging plants. Species responses to climatic variables were unrelated to their range sizes. Main conclusions The close relationship between leaf and soil nutrients indicates a specialization of narrow-ranging species to particular habitats whereas wide-ranging species may be able to better withstand changes in environment such as soil fertility over a large area.