Vegetation has large applications in bioengineering practices. Root system provides an additional reinforcement whose effects depend on the biotechnical properties. This study evaluates the changes in the additional root cohesion under different conditions of plant-growth, e.g., exposure to light, water and nutrient availability. These determine different root system development in terms of root length, density, root diameter profile, total number of roots. A root topological model is used to simulate the root architectures, which are then coupled with a Root Bundle Model to estimate the additional root strength. Finally, this study proposes a rigorous method to compute the additional root cohesion from the tensile strength.