Root vascular traits differ systematically between African savanna tree and grass species, with implications for water use

Premise Belowground functional traits play a significant role in determining plant water-use strategies and performance, but we lack data on root across communities, particularly the tropical savanna biome, where vegetation dynamics are hypothesized to be strongly driven by tree–grass differences water use. Methods We grew seedlings of 21 tree 18 grass species (N = 5 individuals per species) from southern African biome under greenhouse conditions collected fine-root segments plants for histological analysis. identified measured xylem vessels 539 individual cross sections. then quantified six vascular anatomy tested them phylogenetic signals trait values associated with vessel size, number, hydraulic conductivity. Results Grass roots had larger than trees, higher proportion their cross-sectional area comprised vessels, they estimated axial conductivities while trees number grasses did. found evidence associations between relatedness most these species, not grasses. Conclusions Our findings support hypothesis that have transport capacity terms maximum conductivity, consistent observation more “aggressive” users high soil moisture availability. study identifies may drive differential responses