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Landslides occur when gravity overcomes the force of friction at ground level. This effect can be caused by rainfall, changes in ground water flow, disturbance of slopes by constructions or a combination of these factors. Landslide prone areas include steep slopes, channels along streams and rivers or where land is heavily saturated with water, and land that has been modified due to human activities, such as deforestation or construction. Mauritius, with its mountainous relief in many places and steep slopes, is subject to these natural calamities. These natural disasters can be quite damaging when they occur and they tend to be very unpredictable. In pristine Mauritius, areas left bare by landslides were rapidly colonised by native and endemic quick growing pioneer species, whilst slower growing canopy species emerged in a second stage…
Deforestation, degradation of the environment, replacement of canopy trees with maladapted introduced species, infrastructure, climate change and careless land use planning increase the frequency and severity of landslides. Furthermore, landslides threaten our native and endemic biodiversity, since recolonization will favour fast growing invasive alien species e.g. goyave de Chine, privet, piquant loulou, Tecoma stans, liane papillon etc over slower growing native and endemic species such as bois d’olive, ebonies, vacoas etc. The endemic plants that survive the landslide may not live long due to the disturbance caused by the event. As a result, specialist animals that depends on these plants for foraging and nesting lose these precious natural resources.
In recent times, landslides have been observed in several sites including Corps de Garde mountain and Le Pouce in 2022, Brise Fer, Simonet and Le Morne in 2023. The landslides have left large visible traces on the Corps de Garde mountain, which are rapidly disappearing as invasive alien plants colonise these spaces.
When a landslide happens in an area populated by rare native or endemic plants or animals (e.g. endemic snails and insects), it could cause their extinction or severe reduction in a blink of an eye. These landslides being vastly unpredictable, it raises the need to have backup populations of species that thrives on sites that are prone to landslides. In our nurseries, our teams propagate seedlings of a list of rare species to ensure that a natural disaster such as a landslide does not put our species on the brink of extinction.
In addition, for ecological restoration, we advocate using native and endemic species that are more adapted to our climatic conditions, have dense root networks (such as native grasses, sedges and ferns), wider roots (such as buttress roots), and have a longer lifespan. These species also have other ecosystems services such as support to wildlife and carbon sequestration.
