Comoran Broadleaf Scrub Forest

This varied vegetation is now largely limited to small groves enclosed by coconut plantations and along the shore. On Aldabra it comprises a mixture of tall shrubs growing to a height of about 12 m. These include Dracaena reflexa, Macphersonia madagascariensis, Polysphaeria multiflora and the Aldabran endemics Calophyllum inophyllum (Clusiaceae), Flacourtia ramonichii (Salicaceae) and Psychotria pervillei (Rubiaceae). There are also open stands dominated by Guettarda speciosa on the eastern part of South Island from the Dune Jean-Louis area eastwards. It ranges in height from 3-6 m and frequently includes the Aldabran endemic Solanum aldabrense (Solanaceae). Broadleaf forest also occurs on various other islands including Astove, Bird, Cosmoleda, Desroches and D’Arros. 

 

Comoran Pemphis Bush

Mainly associated with low-lying very rough, sharp ‘champignon’ or pitted limestone, this formation is almost entirely composed of Pemphis acidula bushes. It is a distinctive sclerophyll scrub that often forms a narrow belt outlining mangrove areas. There are also broader belts along part of the lagoon coast and on part of the north coast and south coast west of Dune d’Messe. On Aldabra the few associated plant species include the Aldabran endemics Sideroxylon inerme (Sapotaceae) and more locally Vernonia aldabrensis (Asteraceae). Pemphis scrub is also an important vegetation type on Astove, Europa and Cosmoleda, but has a restricted distribution being found no further north than the southern Amirantes and Providence and is absent from the granitic Seychelles.

 

Comoran Mixed Scrub and Scrub Woodland

Comprising open broad-leaf evergreen formations this vegetation usually forms stands ranging from 3-5 m tall but can reach 7 m. It occupies large areas of the raised limestone islands and supports most of the endemic species. On Aldabra it contains about 50 species of shrubs and small trees. The most conspicuous of these are Apodytes dimidiata, Canthium bibracteatum, Euphorbis abbottii, Ficus avi-avi, F. consimilis, F. nautarum, F. thonningii, Maytenus senegalensis, Mystroxylon aethiopicum, Ochno ciliata, Pandanus vandermeeschii, Polysphaeria multiflora, Terminalia fatraea and the Aldabran endemics Erythroxylon acranthum (Erythroxylaceae), Grewia aldabrensis, G. salicifolia (Tiliaceae) and Sideroxylon inerme (Sapotaceae). Less frequent but still notable are Allophylus alnifolia, Dracaena reflexa, Guettarda speciosa, Jasminum elegans, Phyllanthus cheloniphorbe, Scaevola taccada, Sarcostemma viminea and the Aldabran endemics Acalypha claoxyloides (Euphorbiaceae), Clerodendron glabrum (Verbenaceae), Flacourtia ramontschii (Salicaceae), Secamone freyeri (Apocynaceae) and Terenna supra-axillaris (Rubiaceae). Among the field layer species are various herbs including several sedges and the conspicuous succulent Lomatophyllum borbonicum. On Aldabra, but no longer on other islands, several species of this formation are browsed by tortoises and there is often a distinct browse line at about 0.6 m. Many of the trees seem to be arranged in rows and generally lean in a westward direction. This curious arrangement is thought to be due to the prevailing Trade Winds.

 

Comoran (Aldabran) Tortoise Turf

This distinctive association occurs in areas of high tortoise concentrations at the east end of Aldabra where there is a terrain of flat limestone and shallow soils. The plants include grasses such as the Aldabran endemics Eragrostis decumbens, Panicum aldabrense and Sporobolus aldabrense (Poaceae), sedges such as the Aldabran endemic Bulbostylis basalis (Cyperaceae) and a variety of other herbs. The heavy grazing ensures that the plants are cropped close to the ground and many of the species appear to be genetically dwarfed. In fact, of the 22 species recorded 12 are considered to be dwarfed forms. Other component species include Bacopa monnieri, Bryodes micrantha, Cyperus pumilus, Euphorbia prostrata, Evolvulus alsinoides, Fimbristylis ferruginea, Justicia precumbens, Mollugo oppositifolia, Phyllanthus maderaspatensis, Sida parvifolia, Tephrosia pumila and several endemic species most of which are confined to Aldabra. These include Cassia aldabrensis (Fabaceae), Dactyloctenium pilosum (Poaceae), Euphorbia stoddartii (Euphorbiaceae), Phyllanthus mckenziei (Phyllanthaceae), Sporobolus testudinum (Poaceae) and Stenotaphrum clavigerum (Poaceae).

Further information required.

 

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