Which biotic drivers can better explain the variability of root mechanics of tropical tree species?

Background and Aims Little quantitative information is available on the protective role of tropical species on slope sites prone to erosive phenomena. One of the key parameters to evaluate of species’ capabilities in erosion mitigation is root individual scale mechanical traits. We explored, for the first time, the variability of root mechanics of several dominant species in tropical ecosystems. Methods We carried out ex situ experimental tests on roots of four common tropical tree species, i.e. Barringtonia fusicarpa Hu, Pometia pinnata J.R. Forst. & G. Forst., Baccaurea ramiflora Lour. and Pittosporopsis kerrii Craib as model species in Xishuangbanna forests, Yunnan, China. Tensile strength and modulus of elasticity, as two of the most important root mechanic traits were estimated. Results and Conclusions Root mechanics vary greatly depending on root size and tree species. And root size the primordial factor determining the variability of root mechanics, especially for very fine roots. The significant disparity of root mechanics between the four tree species suggests that the use of generic equations in soil stability modelling procedures may not be relevant in tropical ecosystems that possess a high species richness level. General discussions are provided concerning the disparity of geomorphological modelling between temperate and tropical forests.