Terrestrial biodiversity
The Republic of Mauritius is part of one of the world’s biodiversity hotspots. The forest in Mauritius covers around 25 % of its land area of which 2 % is classified as (‘good quality’) native forest, i.e. forest with more than 50% canopy cover. In Rodrigues, the exotic planted forest cover is estimated around 30 % of Rodrigues land area (Forestry Services, Rodrigues). The flora and fauna of Mauritius has a relatively high level of diversity and endemism as a result of the island’s location, age, isolation and varied topography. Mauritius has 691 native plant species of which 273 are single island endemics and another 150 are Mascarene endemics, Rodrigues has 150 native plant species, of which 47 are single island endemics, and 72 are Mascarene endemics. The only native mammals are bats, and 9 remaining endemic bird and 11 remaining endemic reptile species. Mauritius’ mainland forest area and Protected Areas (PA) spatial extent has remained unchanged since 2010. The area under native forest restoration in Mauritius has increased by over 500% since 2010 (PAN Project, NPCS, FS). Knowledge about some species such as reptiles is increasing, but gaps still exist for other species such as insects in terms of scientific baselines, and conservation status.
The pressures from human activities and natural factors have highly modified Mauritius’ ecosystems. Development in general has had a disastrous effect on the native flora and fauna, through forces such as the introduction of invasive species of plants and animals, habitat destruction and modification, pollution, pests and diseases, and climate change; and all of these forces have increased the vulnerability of species and ecosystems to natural disasters.
The forests of the Republic of Mauritius are small in area but perform vital functions, among the most important of them being soil and water conservation. The roles of forests in reducing soil erosion, carbon sequestration, conservation of biodiversity and genetic resources, and providing recreation and ecotourism activities are now widely recognised and valued. Consequently, conservation, protection and development of the remaining native forests through sustainable management are priority objectives of the overall national policy. In fact, the forests of the Republic of Mauritius are now managed more for these environmental functions than for the production of timber.
Mauritius has 691 species of which 273 are single island endemics and another 150 are Mascarene endemics, Rodrigues has 150 species, of which 47 are single island endemics, and 72 are Mascarene endemics. Nine of the endemic species in Rodrigues are represented by fewer than 10 mature individuals in the wild, including three species which are known from just a single individual. Of its native flowering plants 39 % are unique to Rodrigues and 54 % unique to the Mascarenes (Mauritius, La Reunion and Rodrigues). Other species groups show similar levels of endemism. 61 of the country’s native species are already classified as Extinct, 141 of the flowering Mascarene endemic plant species are classified as Critically Endangered, 55 species are Endangered and 98 are classified as Vulnerable. While in 2012, 192 native plants species were classified as Critically Endangered as per International Union for Conservation of Nature criteria (IUCN) of which 43 had been successfully propagated. There are about 200 species, subspecies and varieties of pteridophytes (ferns and fern allies), of which 13 species are endemic and 40 are extinct. There are 207 taxa lower plants consisting of 89 genera of mosses and 59 genera of liverworts.
Reptiles: Of the 17 reptile species that used to be found in Mauritius, only 12 remain of which 11 are endemic species, and 7 of these are restricted to offshore islets where they escaped extinction from rats. Five of these species are restricted to Round Island.
Birds: Nine endemic landbirds are found in Mauritius. Two endangered bird species are endemic to Rodrigues: the Rodrigues fody (Foudia flavicans) and the Rodrigues Warbler (Acrocephalus rodericanus).
Bats: Bats are the only native mammal in Mauritius and Rodrigues. Two species of fruit bat currently occur in the Republic of Mauritius: Pteropus niger in Mauritius and Pteropus rodricensis in Rodrigues.
Positive trends have been registered for endemic species of which 5 fauna species (4 birds and 1 bat) have been down-listed the last four years on IUCN Red List of Threatened Species from Critically Endangered to Endangered (Mauritius echo parakeet (Psittacula eques), Mauritius fody (Foudia rubra)), Endangered to Vulnerable (Mauritius fruit bat (Pteropus niger)), and Vulnerable to Near Threatened (Rodrigues fody (Foudia flavicans), Rodrigues warbler (Acrocephalus rodericanus)). Negative trends have been registered for two bird species: Mauritius kestrel (Falco punctatus) and Mauritius cuckoo-shrike (Coracina typica) from 2002 to 2013. In 2010, largely due to the habitat restoration work, the population of Rodrigues warbler has increased from 30 individuals in 1970s to 4,000 individuals in 2010.
In Rodrigues, the protection and monitoring of fauna concerns the Rodrigues fruit bat (Pteropus rodricensis), and two endemic and endangered birds species: the Rodrigues fody and the Rodrigues warbler. The major threats to these species are IAS, cyclones and habitat loss.
In 2013, the total extent of forest cover in Mauritius mainland was estimated at 47,108 hectares representing about 25 % of the total land area. The forest cover is composed of planted forests, native forests (2 %), and shrub-land (14 %). Mauritius forestland categories (public 47 % and private 53 %) show marginal changes from 2010 to 2013. In 2013, the extent of reasonable quality native forest (>50 % of plant canopy cover) was estimated at around 2,600 ha. The Forestry Services (FS) observed that the pattern of forest distribution is changing. These changes might be partially attributable to climate change issues but in-depth studies need to be carried out.
In Rodrigues, the total extent of planted forest cover is estimated to be approximately 30 % of the total land area. Invasive alien woody species such as Acacia nilotica dominate all forest areas on Rodrigues and, with the exception of intensively restored areas in the nature reserves, no contiguous areas of native forest exist. Acacia nilotica is mostly spread through the faeces of grazing animals being given that there is an extensive grazing system on the island. About 20 % of the island’s total forest cover is now dominated by Acacia nilotica. Elements of the original biodiversity remain in some forest fragments. The Rodriguan endemic bois papaye (Badula balfouriana), with only five remaining individuals in the wild, is being propagated in the MWF Solitude Nursery.
The main threats to forest biodiversity are invasive alien species (IAS) and limited management of the IAS on forest lands, limited land availability and habitat fragmentation, climate change, pests and loss of between-species interactions (e.g. pollination). Mauritius and Rodrigues have lost the majority of their endemic vertebrate species among which were important browsers like land tortoises, pollinators and seed disseminating frugivores. Such losses are expected to have adverse effects on the native plant communities by reducing habitat heterogeneity (e.g. due to loss of browsers), reducing reproductive success (e.g. through lowered pollination levels) and reducing plant establishment and survival (e.g. through poor dissemination from mother plants).
The priority now for Mauritius and Rodrigues is the restoration of endemic forests (9 % of highly degraded forest in Mauritius) by weeding invasive alien species. In Mauritius, the sites selected for restoration are found in the National Parks, Nature Reserves and other State Land Forests. As of late 2016, about 485 ha of native forests are under active management toward restoration in Conservation Management Areas (CMA). Most of these plots are concentrated in key biodiversity sites on public and private lands. In 2009, approximately 50 % of the state plantation areas (some 6,000 ha of exotic plantations) have been set aside for the protection of ecosystem services (water catchments, soil protection, etc.). In 2014, public private partnerships (PPP) have been initiated (Vallée de Ferney, Ebony forest). IAS threat is countered in forest areas by native forest restoration. The area under native forest restoration in Mauritius has increased by over 500% since 2010. Restoration work formerly undertaken by government agencies for initial weeding, used a strategy of contracting out to intermediary bodies but this was costly. Now NPCS directly supports community work by recruiting local labourers on contract who perform weeding operations under NPCS supervision and control. This strategy has considerably reduced the cost of weeding and it also helps to raise awareness among local communities on native forests biodiversity conservation and its positive impacts on livelihoods. In Rodrigues, plant conservation programmes are implemented through the Rodrigues Forestry Service, community forests, private sector initiatives and the Jardin des Cinq Sens Botanical Garden.