Variation in leaf and root functional traits of Caragana jubata across different provenances in a common garden

Environmental and genetic differentiation jointly influence intra-specific variations of plant functional traits. Research on this topic is of great importance for the assessment plant adaptation to climate change and for developing long-term conservation strategies. In a common garden experiment, we investigated the variations in root and leaf functional traits of Caragana jubata across 14 provenances, as well as their relationships with the climatic and geographic factors of seed origin. The results showed that there were significant intraspecific differences in leaf tissue density, specific leaf area, leaf length to width ratio, leaf shape factor, leaf chlorophyll content, leaf nitrogen concentration, as well as root average diameter, specific root length, specific root area, and root nitrogen concentration. Leaf tissue density and root nitrogen concentration were key indicators explaining the differentiation of leaf and root functional traits across the various provenances. There were significant trade-offs among leaf and root functional traits, as indicated by the significant negative correlation between leaf area and leaf tissue density, between specific root length and root tissue density, as well as between leaf nitrogen concentration and root nitrogen concentration. Mean annual precipitation, growing season precipitation, altitude and geographical factors (longitude and latitude) of the seed origin played crucial roles in influencing intraspecific variation of leaf functional traits, while altitude dominantly accounted for the intraspecific variation of root functional traits.