Mechanical traits of fine roots as a function of topology and anatomy

Root mechanical traits, including tensile strength (Tr), tensile strain (εr) and modulus of elasticity (Er), are key functional traits that help characterize plant anchorage and the physical contribution of vegetation to landslides and erosion. The variability in these traits is high among tree fine roots and is poorly understood. Mao et al. explore the variation in root mechanical traits as well as their underlying links with morphological (diameter), architectural (topological order) and anatomical (stele and cortex sizes) traits.

Cross sections of roots

The authors find that root topological order plays an important role in explaining variability in fine-root mechanical traits due to its reflection of root tissue development. Accounting for topological order when measuring fine-root traits therefore leads to greater empirical understanding of plant functions (e.g. anchorage) within and across species.

Their study has implications for future research on tree, shrub and herbaceous species. Both woody and herbaceous plants play important roles in slope stabilization and in reducing soil erosion. In urban ecosystems or plantations, root tensile strength is related to the likelihood of uprooting during wind storms. Many herbaceous plants are also subjected to additional tensile forces associated with grazing, yet mechanical traits are rarely included in most studies of plant function and ecology. Future work incorporating root mechanical traits into functional ecology while also considering root system topology and morphology will enable better understanding of plant growth and functioning at both the individual and the community level.

Further reading

Mao, Z., Wang, Y., McCormack, M. L., Rowe, N., Deng, X., Yang, X., … Stokes, A. (2018). Mechanical traits of fine roots as a function of topology and anatomy. Annals of Botany. https://doi.org/10.1093/aob/mcy076