vegetation37forettropicale-creditirt-emmanuelvirin.jpgVegetation37forettropicale Creditirt Emmanuelvirin.jpgVegetation37forettropicale Creditirt Emmanuelvirin.jpg© Emmanuel Virin
© Emmanuel Virin

Indigenous flora

The origin of significant endemism* important

The flora of Reunion, like that of other intertropical oceanic islands, is the result of slow and selective immigration (indigenous species*), and of speciation processes that, although recent in geological terms, have given rise to significant endemism.*

Lacking mobility, plants naturally disperse their seeds passively: via sea currents (sea vector), winds and cyclones (wind vector) or even via birds (animal vector). Isolated in the middle of the Indian Ocean, Reunion has remained a difficult destination to reach! Only certain species were able to make the journey and become established. The original plant colonisation relied on the closest continental areas (nearly 70 per cent of the flora comes from Madagascar and East Africa).

Spontaneous flora

The spontaneous flora of Reunion currently includes** 1,730 vascular plant species, including 1,478 spermatophytes*** (85.4%) and 252 pteridophytes (14.6%). It is divided into:

  • 848 indigenous species (of which only 86 are likely to be native), or about half (49%) of the spontaneous flora. Among these species:
  • 237 (28%) species that are strictly endemic to Reunion
  • 153 (18%) regional endemics, also growing in the other Mascarene Islands (Mauritius and Rodrigues)
  • 458 (54%) simply indigenous species, which can also be found in their country of origin
  • 829 exotic species,* approximately the other half (48%)
  • 53 cryptogenic species,* or 3%.

Great diversity

Although the native flora of the island presents a relatively low diversity of plants, it offers a high level of endemicity (28 per cent of species are strictly endemic and 46.6 per cent are totally endemic), which gives it global importance. Reunion is recognised as one of 25 biodiversity hotspots in the world.

Vegetation linked to the history of the island

When humans settled on the island in the mid-17th century, Reunion’s flora was enriched by exotic plants that gradually became more and more established as the population of Reunion grew. Their wide range of uses (agricultural, forestry, economic, medicinal, ornamental, etc.) and the increase in trade in goods and people led to the voluntary and involuntary introduction of several thousand species from both tropical and temperate regions around the world. A number of these species have today become a real threat to the native flora.

Fragile native flora

Insularity and micro-endemicity are factors that contribute to the fragility and vulnerability of native flora, and thus to increasing the risk of extinction and biodiversity crises in oceanic islands.
The alteration and destruction of habitats have had a devastating effect on the island’s biodiversity. Although the process has slowed down considerably due to the combination of community vigilance, a proactive policy of preserving native habitats and the conservation management of native biodiversity, the indigenous vegetation continues to diminish in places.

The destruction of habitats

Disturbances created by humans (fires, wild grazing and fodder seeding in altimontane areas, planting in the undergrowth, wild camping, the opening of trails, excessive visitor numbers, etc.) are topical examples that illustrate the more global issue of biological invasion by introduced species. These invasions are considered globally by the International Union for the Conservation of Nature (IUCN) as the third most important factor in the loss of biodiversity after habitat destruction and species overexploitation.

Endangered species

Today, 256 species are considered endangered in Reunion (according to IUCN criteria), or 30.7 per cent of the native flora. Of these endangered species, 125 are now critically endangered (at least in the wild).
Sustainable development projects are therefore crucially important to .

Knowledge of the native flora and the environments and their fragility is key to promoting their preservation. Developing tourism that respects Reunion’s natural environment requires that everyone play their part in safeguarding this unique heritage.

Notes

*Characterisation of plant species

** ACCORDING TO THE 2008 EDITION OF THE INDEX PUBLISHED BY THE CONSERVATOIRE BOTANIQUE NATIONAL DE MASACARIN.

*** SPERMATOPHYTES ARE SEED-PRODUCING PLANTS AND NOT SPORES LIKE MOSSES, LICHENS AND FUNGI, WHICH ARE STILL VERY RARE ON THE ISLAND.

Article written by the Jardin Botanique de La Réunion

 

 

An indigenous, or native, species is one that arrived naturally on the island.

 

An endemic species is an indigenous species that has evolved into a new species, growing naturally in a specific place.

An exotic species is a species that has been introduced by humans from other countries.

A cryptogenic species is a species that is potentially indigenous but whose status is still obscure due to lack of verified evidence.

An invasive species is an exotic species that has become virtually uncontrollable, posing a real threat to native species.

Don't leave like that !

There is still a lot to discover