Root reinforcement and slope stability modeling: a review Rooted soils are comparable to composite materials that have very heterogeneous mechanical properties. The analysis and quantification of these properties and their change over time is very time-consuming and complex, but central to many practice-relevant aspects of soil bioengineering and protection forest management. The article summarizes recent knowledge and approaches for the quantification of so-called root reinforcement – the reinforcement of soil by roots – and its implementation in slope stability models. Root reinforcement involves four mechanisms: basal root reinforcement, lateral root reinforcement under tension, lateral root reinforcement under pressure, and stiffening of the landslide body. Recently, the SlideforNET/SlideforMAP and SOSlope models have been developed for practical use. SlideforNET is an online tool that allows to assess the likelihood of shallow landslides and the protective effect of forest cover within a few minutes. SlideforMAP is based on the same approach as SlideforNET, but is spatially distributed and takes into account the forest structure in a catchment area or a region in detail. In particular, SOSlope supports the quantification of the protective effectiveness of forest stands as well as the planning of protection forest management and of soil bioengineering measures. Initial pilot projects show that the models enable the transition from a “qualitative” to a “quantitative” soil bioengineering.