I consider that a dense root system will retain more soil since it covers more volume than a less dense system. If you look at the roots, the hairs usually have a lot of soil attached to them, therefore a system with many branches and young roots will be able to act like a network maintaining soil and preventing erosion.

I have also seen that specie like grass, which grow by covering the soil and surface with newborns around them are also good retaining soil because they create a more complex network underground and above ground they cover the soil with their leaves, protecting from the rain and the wind.

I have seen places where erosion was stopped just by having grass on the slopes.

Here the problem is the surface, they cannot protect deep surfaces.

Plant should have good canopy coverage and it should be wide spread root system so that more soil parrticals can be retained and bonded. when we want to minmise the soil erions we must  use both bio engineering measure. The is big list of plants for conservation pointwivew is given in the book authored by Sikka etal 1999, Dhrownaryana etal others in India.

Dear Ofelia and Subhash, 

Thank you for your experience feedback

Root traits are often considered the main plant traits to reduce erosion and runoff.

But in situations with high intensity of runoff and erosion, shoot traits really contribute to reducing erosion and runoff.

What are the main traits reducing erosion and runoff presented in famous handbooks of Cornelissen et al. 2003 and Pérez-Harguindeguy et al. 2013 ? 

Best regards

Michel-Pierre

Thanks for sending the references, I will take a look

In attach a review about important root traits for ecological engineering

I'm not an expert in shoot/root traits, but from experience in a semi-arid environment, I would say that an addtional set of traits to consider would be reproductive strategies. Perennial grasses with strong rhizomatous development and deep root system appear to provide very good soil binding services. In our part of the world (southern Africa) Cynodon dactylon is an excellent example of this type of grass - highly drought resistant, resilient to high grazing pressure, and capable of developing a very deep root system.

1.In Rwanda most of the progressive terraces had Pennisetum purpurem as stabilising plant, not only because of robust roots, high-valued forage and easy propagation, but also because of a lot of partly stiff crop-residues covering the soil-surface. 2.In Ethiopia I observed that Euphorbia tirucalli or Sesbania sesban with their solid canopy reduced the impact of hefty high-intensity downpours of rains on and near the contour-bunds.

Dear Mike and Bernhard, 

thank you very much for your responses including the plant species candidates to perform soil stability and reduce soil erosion and your field experience in tropical Africa.

However, highlighting ecosystem services such soil retention stability based on identification of species without reference to plant trait are limited only to local pool of species and present difficulties of plant taxonomy notably in some tropical regions and make the relationship plant species with plant functions.  

The purpose of my question is to list all the plant traits (root, shoot, life cycle,...) reducing erosion and runoff.

Best regards

1. From a.m. answers you can conclude some 5-10 traits, many others are nearby. 2. Important is the simple listing of species and their specific traits. 3. Many dev. workers / actors in the tropical water-sheds will be happy to see them listed and put into a transparent network. Many thanks in advance for that. 4. While we are "quarreling" about academic sophistications and contextual finickiness, thousands of cubic-meters of fine top-soils are eroding down in countles watersheds. So your question and evolving dialogue will be very helpful.