Natural History

Socotra is characterized by the unique land and marine biodiversity. The island itself measures approximately 125 kms long by 45 kms wide and covers a total area of 3665 sq kms.  Topographically it can be divided into three main zones: the coastal plains, a limestone plateau and the Hagghir Mountains. The island is sparsely vegetated and dominated by xenomorphic (drought resistant) forms which are well adapted to the harsh conditions, including the desiccating effects of sun and wind. Only in sheltered valleys and higher mountain areas is the vegetation more luxuriant. Open deciduous shrubland of the coastal plains and low inland hills is dominated by the common shrub Croton socotranus and the bizarre tree succulents, the desert rose, Adenium obesum socotranum, and the cucumber tree, Dendrosicyos socotranus. Higher altitudes are home to a variety of frankincense trees, three endemic Suqotran aloes, and wild pomegranate. One of the most famous botanical curiosities of Suqotra is the dragon’s blood tree (Dracaena cinnabari) which is restricted to the zones of submontane thicket and montane grassland. The tree is so named because any injury to the bark results in a deep red liquid exuding from the scar. It was compared  to the "blood of Abel” in ancient history. It is called Dum al Axwein, “blood of the two brothers” Cain and Abel, in the present day Arabic language. The Suqotri name “Arriyahib” has no connection to the Arabic.

 Flora

 

 

Scientists first reached the remote Socotra Archipelago in 1880, when Scottish botanist Isaac Bailey Balfour collected around 500 plants. Over 200 were species new to science. To date, approximately 900 vascular plants have been recorded from Socotra, of which between 300(including some fifteen species restricted to Abd al Kuri) are found nowhere else (i.e. endemic species) they create weird vegetation - and make the archipelago the world's tenth richest island group for endemic plant species.

Many are strange-looking remnants of ancient floras which long ago disappeared from the African/Arabian mainland.

Socotra’s flora has strong links with adjacent parts of Somalia and Arabia but some species and genera have interesting disjunctive distributions: Dracaena cinnabari, the Dragon's Blood tree, is a tertiary relict with related species in southern Arabia, north-east Africa and the Canary Islands; species of Kalanchoe and Helichrysum show strong links with southern African species but perhaps the most strange distribution is that shown by the genus Thamnosma with T. socotrana on Soqotra and related species in southern Arabia, south-west Africa and south-west North America. Socotran’s flora includes plants which can be considered taxonomic relicts, that is with no close relatives, these include: Dirachma socotrana, one of only two species in the Dirachmaceae, a family related to the Malvaceae but with an interesting mixture of characters including 8 merous flowers, stamens opposite the petals and fruits with a dehiscence similar to that found in Geranium; Dendrosicyos Soqotranus the only arborescent member of the Cucurbitaceae and Wellstedia a small shrub of boraginaceous affinities but which is sometimes placed in a family of its own.

There is one sub-endemic family - the Dirachmaceae (recently a second species has been found in Somalia) and ten endemic genera: Angkalanthus, Ballochia and Trichocalyx (Acanthaceae), Duvaliandra and Soqotranthus (Asclepiadaceae), Haya (Caryophyllaceae), Lachnocapsa (Cruciferae), Dendrosicyos (Cucurbitaceae), Placoda (Rubiaceae) and Nirarathamnos (Umbelliferae). The families richest in endemics are Compositae (26), Acanthaceae (24), Euphorbiaceae (21), Labiatae (20) and Asclepiadaceae (11).

Perhaps the most notable of these are the podagrics or swollen-stemmed trees, these include: Dendrosicyos socotranus - which somewhat resembles a small baobab; Dorstenia gigas and Adenium obesum ssp. socotranum. One of the most interesting trees, and an important potential genetic resource is Punica protopunica. This is related to the pomegranate (P. granatum) but has smaller and less palatable fruits and is the only other species in the family Punicaceae. Several species on Socotra are of horticultural interest for instance Begonia socotrana, the hybrid parent of winter-flowering begonias, and Exacum affine - the Persian violet.

The least studied groups are the lichens, bryophytes and fungi. The people living on Socotra, especially the Bedouins, have a thorough knowledge of the flora, and many of the plants have traditional uses, such as providing livestock fodder, fuel, building materials, foods, gums, or resins. The majority of islanders still rely on livestock - and thus of necessity on the vegetation - for their survival. And the many sheep, goats, camels, cattle and donkeys of the island are supported solely by the island's vegetation.

Plant extracts are still used in medicines, cosmetic and hygiene preparations, and in the manufacture of cordage, as a source of insecticide, and in tanning and dyeing. (Click hear to learn more about the flora traditional uses).

Fauna 

 

Socotra's fauna is just as fascinating. Among the land birds Socotra Island is home to 180 species of birds 6 species are endemic, ((Socotra sparrow – Socotra Cisticola – Socotra Starling – Socotra Sun bird –Socotra Warbler – and the rarest Socotra Bunting ( estimated with 1000 specimens alive) )).  as well as 14 sub-species, are restricted to Socotra. And also it’s a host point for many immigrated/breeding birds of over 45 species such as Flamingos, Kettle Egrets, Reef Hearns, Gulls, etc. And the highest density in the world for Egyptian Vulture has registered on the island.

More work is still needed to clarify the status of other species.

 

There are 190 species of butterfly and with a large number of endemics. The reptilian and insects fauna is also very rich 600 species of insects with 90% with high proportion of endemic. The reptilian fauna is also very rich with 19 out of a total of 22 species regarded as endemics.

 Goats, shapes, caws, donkeys, and camels are common to come across. Bats and civil cat is the only mammals native to the island.

In the marine world Socotra has taken a spectacular place as it has mixture of species from different biogeography regions- the western Indian Ocean, the Red sea, East Africa and the wider Indo-Pacific. Despite of the small archipelago, Socotra Island is home to more than 680 Species of fishes are comparable to those of the Red Sea. and about 230 species of hard corals (five are endemics) and 30 species of soft corals. In addition to 300 species of crustacean (nine are endemics), 490 species of mollusks, and 230 species of algae. Sea-turtles also nest on the north of the island but there is a need for more work on these (as with almost all Socotra's wildlife). An endemic fresh-water crab, Potamon socotrensis, is common in the temporary water-courses. In general the fresh-water habitats of the island have been little studied and it is still not clear whether there are endemic freshwater fish living there. Among the insects it is not surprising to find many forms with reduced wings, lessening the likelihood that they are blown off the island.

From a biogeographic perspective, Socotra is more closely linked with Africa than Arabia but there are also interesting affinities with other island groups such as the granitic Seychelles and even some remote islands of the Atlantic Ocean. There remains a great need for further studies of individual species and of main habitats on Socotra. To date, for example, there has been very little work done on the southern and western plateau, the more isolated granitic pinnacles, as well as the major part of the islands' coastal waters.

Its unique character makes Socotra a natural World Heritage site. In practice however what matters is the effect on the ground. There is little doubt that potential revenue sources for the local population must be developed and these may include small-scale tourism, the cultivation and export of native plants, or the collection and storage of seeds and cuttings for propagation as part of international programs.

Given the social and developmental pressures which are now a fact of life on Socotra the continued survival of many endemic species, and of unique habitats is at risk. Socotra provides both an opportunity and a challenge for mankind. Fortunately the concept and value of conservation is still high on the agenda of the island's people. It is to be hoped that local and national efforts to protect Suqotra's unique wildlife are supported by international assistance and that the island's uniqueness is maintained for the benefit and pleasure of future generations.

How to Conserve Socotra Island?

 

The floras of oceanic island are often particularly rich in species and show a high degree of endemism. Socotra is no exception. It has one of the richest island floras in the world - on a par with those of the Galapagos, Mauritius, Juan Fernandez and the Canary Islands. However, island ecosystems are often fragile and their native species vulnerable to overgrazing from introduced herbivores and to being out-competed by exotic plant species.

The threats to the Socotran flora can be illustrated by considering the fate of the vegetation on other oceanic islands. The decimation of Dracaena draco on the Canary Islands and Madeira is a particularly relevant example. On Socotra Dracaena cinnabari is widespread over the centre and east of the island and is the dominant tree in some areas. In the Canary Islands its closest relative, D. draco, is reduced to five trees on Madeira and is extinct on four of the seven Canary islands with no more than 200 trees surviving on the other three islands. On St Helena the vegetation has been almost totally decimated. Goats were introduced on to the island in 1513. By 1800 the forests which originally covered the islands were reduced to a few remnants and it has been estimated that, of the probable 100 endemics on the island, only 40 now remain.

There were undoubtedly drastic changes to the vegetation and widespread extinctions in the past but now a balance seems to have been established between man and nature. There is no evidence to suggest that the situation on the island has changed much since Balfour's visit in 1880. There seem to have been no extinctions since Balfour's time and certainly the suggestion that the island's flora has been decimated by huge goat herds (Lucas et al. 1978 etc.) is totally unfounded. However, proposed development on the island could see the situation deteriorate very rapidly.

 


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Last modified: 09/18/06