How does vegetation influence the susceptibility of grassland slopes towards shallow erosion?

Vegetation plays (amongst other factors) an important role for the stability of slopes near their surface. Not only woody vegetation (i.e. shrubs and trees) but also herbaceous vegetation (dominating grasslands) can enhance the resistance of soil against shallow erosion. Being to some extent controllable via land management (in contrast to other factors, such as topography or the geological setting), vegetation and its impact on slope stability are of high interest for erosion prevention.

In a recent literature review in the journal Earth-Science Reviews, members of the ERODYN team summarize the current knowledge on this topic, and critically discuss the slope stabilization potential of herbaceous vegetation as compared to woody vegetation.

A second paper, just published in the Journal of Environmental Management, seeks to provide insights into the (surface-parallel) tensile strength of the topsoil in subalpine grasslands (< 10 cm depth). In an empirical study, tensile strength was measured in the field, and analysed with regard to potential impacts of soil and vegetation parameters. It turned out that densely interwoven roots and clonal structures often form a surprisingly strong “surface mat” as a small-scale reinforcement of the topsoil, possibly being important for the redistribution of stress. This surface-mat effect depends on the vegetation composition, and certain species provide stronger reinforcement than others. Species with well-developed root systems and a high capacity for clonal growth seem to be most advantageous, but also a balanced nitrogen supply and the plant and structural diversity appear to play a role.

Read more:

Löbmann, M.T.; Geitner, C.; Wellstein, C.; Zerbe, S. (2020): The influence of herbaceous vegetation on slope stability – A review. Earth-Science Reviews, 209, 103328.

Löbmann, M.T.; Tonin, R.; Stegemann, J.; Zerbe, S.; Geitner, C.; Mayr, A.; Wellstein, C. (2020): Towards a better understanding of shallow erosion resistance of subalpine grasslands. Journal of Environmental Management, 276, 111267.

For details on the measurement of the surface-mat effect, see also a previous study performed in montane grasslands: Löbmann et al. 2020, Catena.