A tool used to reverse the destruction of the island is called ‘rewilding’ which is a term to describe returning functionality to an ecosystem. By introducing taxon substitutes to replace missing animals and plants, ecosystems functions such as seed dispersal can be restored.
Mauritius was once home to a giant tortoise Cylindraspis before it became extinct in the mid-19th century. The tortoise would have dispersed the seeds of many endemic trees as well as providing fertilizer for the seeds to germinate in the form of their dung.
Rewilding can be controversial as it can require the intentional introduction of a species to a system outside of its natural range.
Tortoises make excellent candidates for rewilding projects as they are low-risk species as they are easy to control and monitor if they become problematic. Tortoises are also relatively easy to purchase although transport costs are high transporting them to islands.
Choosing a potential species can be problematic for conservation managers but in this case due to the taxonomic and ecological similarities with Cylindraspis, the giant Aldabra tortoise (Aldabrachelys gigantea) originally from the Seychelles and the radiated tortoise (Astrochelys radiata) from Madagascar were chosen.
Pilot studies were carried out before 50 tortoises were introduced on to the island in 2009. After a period of quarantine to ensure they were not carrying prohibited plants, they were released to roam free around the island.
Tortoises suppress the growth of invasive grasses and herbs which allows the planted native seedlings to grow with reduced competition increasing the chance of survival. The small native plants also escape being eaten as they have physiology that deters the tortoises from feeding on them.
As the forest matures the tortoise will aid in disperse the fruit around the island creating a more dynamic more natural forest.
Tortoise turf on Round Island
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