| Popis: |
Purpose Soil moisture availability is a key driver of the relative abundance of trees and grasses in savannas. Fine root morphology influences water acquisition and transport, yet differences in fine root traits between trees and grasses have not been comprehensively quantified across an entire suite of coexisting tree and grass species. Methods We grew individuals of 21 tree and 18 grass species from a Lowveld savanna ecosystem in South Africa under greenhouse conditions and characterized six root traits: root diameter, branching intensity, specific root length, root length to leaf area ratio, distal to total root length ratio, and root length to plant mass ratio. We conducted a PCA to evaluate whether some morphological root traits can act as predictive traits for other, more difficult to measure traits. Results We found strong differences between trees and grasses across all six root morphological traits, particularly root diameter and branching intensity. Trees had thicker roots than grasses, while grasses had higher specific root length, greater branching intensity, a greater relative investment in distal roots, and a higher ratio of root length to plant mass than trees. Despite strong species-level effects on trait values, we found little evidence of phylogenetic signals in trait values for either trees or grasses. Conclusion We found strong evidence of significant morphological differences among savanna trees and grasses. Our results are consistent with the observation that grasses can outperform trees when competing directly for belowground resources. |
