Rodrigues (109 km²) is located 574km east of Mauritius and
the smallest and reputedly the youngest of the Mascarene Islands with rocks
being dated at only 1.5million years old. The island is hilly with a central
spine culminating in Mont Limon (393m). Rodrigues is the only Mascarene
Island with extensive limestone deposits, and is surrounded by a large fringing
reef that encloses eighteen small islets.
Conservation
When it was first discovered in the 16th century,
Rodrigues was probably entirely covered with evergreen, palm-rich forest.
The detailed accounts of Leguat from the early 17th century paint
an idyllic picture of ‘valleys covered with palm-trees, platanes (lataniers),
ebony’s and several other sorts of trees’ and ‘rivulets of fresh water,
whose springs are never dry’. Fire, direct exploitation, clearance for agriculture
and the introduction of alien flora and fauna changed Rodrigues rapidly.
In 1874 Balfour referred to the island as a ‘dry and comparatively barren
spot, clothed with a vegetation mainly of social weeds’.
Currently Rodrigues has the dubious distinction of being
one of the most degraded tropical islands in the world. No contiguous areas
of native forest remain. Nevertheless, its biodiversity importance is still
high with 145 indigenous and 49 endemic plants recorded. The flora of Rodrigues
also includes 6 endemic genera. Nine of its endemic species, however, are
down to less than 10 mature individuals in the wild. Extensive reforestation
programmes in recent years have been almost exclusively of non-native species,
some of which have become highly invasive.
Rodrigues formerly contained at least 12 species of endemic
bird, including the famous flightless Solitaire (Pezophaps solitaria),
two species of giant tortoise, two species of day geckos, two species
of night geckos, an unidentified lizard and one endemic bat. Of these vertebrates
only four species: two threatened bird species, the Rodrigues Warbler (Acrocephalus
rodricanus) and the Rodrigues Fody (Foudia flavicans), the threatened
Rodrigues Fruit bat (Pteropus rodricensis), and a probably
introduced gecko
(Lepidodactylus lugubris) remain.
There are currently three Nature Reserves on Rodrigues,
two on the mainland and the islets Ile aux Cocos & Ile aux Sables (considered
as a single unit) off the north west coast of Rodrigues.
Active conservation work, funded by WWF, began in Rodrigues
in 1985. Several areas in the upland Grande Montagne and lowland Anse Quitor
Reserves were weeded and planted with native trees. This work was undertaken
in collaboration with the Ministry for Rodrigues Forestry Service. The focus
was on rare plant conservation and the planting of native trees.
In 1996 funding was secured for 5 years with the World Bank/Global
Environment Facility (GEF). The focus during this programme has been to
work in areas of forest with a remnant of native vegetation and to use these
as cores areas around which to eventually build a fully functional native
forest. The work is based in Anse Quitor and Grande Montagne. All the work
involves the full collaboration of the Forestry Services.
The first phase of this programme consisted of weeding the
exotic vegetation in selected plots in the reserves followed by planting
of native pioneer species. Once good cover has been secured native "climax"
species will later be planted. Experimental plantings are determining the
best species to use as pioneers, as well as the optimum shading conditions
for the success of transplanted seedlings.
It is planned to experiment in future on different weeding
techniques and the use of rat control to enhance the natural regeneration
work which will enable us to optimise our restoration work to allow larger
areas to be restored.
We are also propagating and replanting very rare plants
in order to secure the future of many species, and the genetic variability
within them.
The nursery & field gene bank. All plants for this programme
are being produced at a nursery in Solitude. In 1998/99 about 50,000 plants
of 44 species were propagated. In addition propagation techniques for rare
plants are being developed. Notable recent successes include the propagation
from cuttings of the Café marron (Ramosmania rodriguesiana) and
Badula balfouriana, now with 12 individuals in the wild.
An integral part of this process of securing species and
the genetic variability is the establishment of a field gene bank. Currently
175 individuals of 9 species are represented in the gene bank. It is planned
to house 35 species in the gene bank at Solitude making it one of the most
extensive in the Southern Hemisphere.
Threats to conservation. In spite of fencing, there are
still occasional incursions of domestic livestock into nature reserves for
grazing. This alerts us to the possible conflicts of interest within nature
reserves, conflicts that are not so apparent in Mauritius. Weeds continue
to be a major threat. Species such as Syzigium jambos, Litsea
glutinosa and Lantana camara have all been introduced deliberately
and people are still proposing (albeit with no ill intent) the introduction
of known invasive plants today. Equally alarming is the increasing numbers
of vertebrate introductions to Rodrigues in recent years. These introductions
have been facilitated by improved communications between Mauritius and Rodrigues,
a lack of inter-island quarantine and a lack of awareness of the potential
deleterious effects of introductions.
Climate
A warm wet season from November to April alternates with
a cool dry season from May to October. Exact temperature and rainfall depend
upon location, but no place receives as much rainfall as the Mauritian uplands.
Some coastal areas are very dry and drought-prone. Rodrigues, like Mauritius
and Réunion, lies in the cyclone belt.
Introduction