Why can the Removal of Vegetation Trigger Mass Movements?
Vegetation is a complex component of the environment, providing many benefits to humans and nature alike. Nevertheless, the removal of vegetation can induce significant and dangerous hazards such as the triggering of mass movements.
In this article, we discuss the various reasons as to why this phenomenon occurs.
1. Loss of Insulation
During the warmer seasons, foliage acts as an effective insulating layer on the surface of slopes. Without the presence of leaves, direct exposure to solar radiation increases the temperature of the earth’s subsurface and consequently of the surrounding atmosphere. The raised surface soil temperatures loosen the earth’s structure resulting in a decrease of cohesion that can eventually lead to mass movement.
2. Reduction in Soil Energy Stability
The presence of vegetation induces a range of positive effects, such as providing stability in soil energy and humus accumulation. Trees and shrubs create a system of roots and significantly help enhance soil strength in sloped ground. Removal of vegetation renders the soil more prone to static and dynamic stresses, thus increasing its potential for mass movements.
3. Change in Hydrological Dynamics
Vegetation plays a major role in the hydrological cycle, by intercepting and retaining water in their structures. An absence of an active dense root network interrupts the impermeable boundary between the surface and subsurface levels, thus weakening the ground cohesion and increasing the risk of mass movement phenomena.
4. Impact on Subsurface Stratigraphy
The density of trees, shrubs and herbs alters the structure of the subsurface in many ways. Through their root system, these species create fractures, thereby changing the soil’s stratigraphy and consequently its ability to resist regular and sudden changes in gravity and permafrost. The absence of vegetation accelerates the erosion process of the soil in cross section, rendering slopes more probable to mass movements.
Vegetation is an essential component of the environment, providing a host of advantages to humans and nature alike. Nevertheless, its removal can have considerable negative impacts on the stability of soil on slopes and subsequently cause mass movements. The various reasons for this phenomena include:
- Loss of insulation due to direct exposure to solar radiation
- Reduction in soil energy stability due to lack of a root network
- Changes in hydrological dynamics due to lack of an impermeable boundary
- Impact on subsurface stratigraphy due to lack of a fractural root network
Therefore, it is highly beneficial for us to take preventive measures to ensure the longevity of our slopes and decrease the likelihood of mass movements.