Naturalist in Socotra

by Dr. Wolfgang Wranik
[Universität Rostock, Fachbereich Biologie,
Freiligrathstr. 7/8,
18051, Rostock, Germany.]

Yemen Update 36 (1995):8-11

In 1993 Dr. Wolfgang Wranik, a biologist from the University of Rostock, participated in a UNESCO mission to Socotra. The following is a report by Dr. Wranik on the island and the urgent need for study and preservation of its biodiversity. [Editor's note]

"Dioscorida is very large but desert and marshy, having rivers in it and crocodiles and many snakes and greatlizards, of which the flesh is eaten and the fat melted and used instead of olive oil." This is part of the oldest documented information on a mysterious piece of land opposite the great Eastern Horn of Africa, called "Dioscorida." This account appears in the"Periplus of the Erythraean Sea", a shipping manual written in the first century A.D. by an unknown Greek sailor. Nowadays, about 2000years later, Socotra still belongs to the comparatively unexplored parts of the world. Apart from some 19th century travel accounts,the island has been a relatively well-kept secret, virtually isolated from the rest of the world and effectively closed for foreign visitors by military considerations and extreme natural conditions. Especially during the time of the south-west monsoon, which blows from April to October, the island is often shut off completely. Even under "normal" weather conditions communications from the mainland byair and by boat are severely restricted by lack of harbours, better airport facilities and adequate aircraft.

The crocodiles and giant lizards mentioned above have never been found in reality on the island, but the natural history of Socotra is one of the most fascinating ones in the world. This unique character is related to its geological history.The separation of Socotra from the African mainland is believed to have occured in the middle of the Pliocene. The high degree of endemism in the flora and fauna is the result of this long isolation from the mainland of Africa. Although the history of the island is in many details still imperfectly known, it is possible to suggest that some of the endemic species are relics of a very ancient flora and fauna surviving in the Haghir massif, which is considered by geologists not to have submerged since the Mesozoic. Also the absence of indigenous mammals is an indication of a very long separation,from a time long before mammals appeared on earth.

These numerous relics and neoendemic forms,which are some of Socotra's most striking features, make the island of remarkable biogeographic and evolutionary interest.

Socotra is about 120 by 40 km and covers an area of 3625 km2. It is composed of a basement complex of igneous and metamorphic rocks of Pre-Cambrian age overlain by sedimentary rocks, mainly limestone and sandstone. Topographically it can bedivided into three main zones. The coastal plains vary considerably in width, up to about 5 km. A limestone plateau extends across most of the island, averaging 300-700 m in altitude. This plateau drops in steep, often almost vertical, escarpments to the coastal plain or directly to the sea. It is dissected by a number of deep valleys.The Haghir mountains in the north-west of the island rise up to a height of 1519 m. They comprise fairly barren-looking granite slopes and pinnacles with montane thicket, woody herbs, and lichens. The climate is monsoonal. There are no exact figures available on the annual temperatures and rainfall, but most rain falls in winter. The mountains are frequently shrouded in clouds and heavy dews are common. These appear to provide a main water source for vegetation in these altitudes.

The island is sparsely vegetated and dominated by xeromorphic forms, which are well-adapted to the harsh climate, such as the dessicating winds of summer. Only in sheltered valleys and higher mountain areas is the vegetation more luxuriant. Different main types of vegetation can be recognised. The most distinctive is the open deciduous shrub land of coastal plains and low inland hills dominated by the common shrub, Croton socotranus,and tree succulents such as the bizarre Adenium and Dendrosicyos. The higher altitudes are home of frankincense,Socotrine Aloe and wild pomegranate. One of the most famous botanical curiosities of Socotra is the Dragon's blood tree(Dracaena cinnabari) which is restricted to the zones of submontane thicket and montane grassland.

Altogether some 815 vascular plant species have been recorded so far, of which 230-260 are endemic. Less studied among the plants are the lichens, bryophytes and fungi. The Socotri people, especially the bedouins, have a thorough knowledge of the flora. Almost all plants have traditional use, such as livestock fodder, fuel, building materials, foods, gums, and resins. Plantextracts are also used as medicines, in cosmetic and hygienic preparations, in the manufacture of cordage, as insecticides, and in tanning and dyeing.

Equally as fascinating is the island fauna,with an exceptional number of endemics, but usually not so striking and above all comparatively poorly studied. About 12 species of mammals are known from Socotra, but all of them have been introduced by man or may occasionally come from the mainland. More than 100bird species have been recorded of which 31 are known, or supposed,to breed. Among the land birds at least 4 species, as well as 14subspecies, are restricted to Socotra. Further taxonomic studies are needed to clarify the status of a number of forms. The coastal area with the shores, sea-cliffs, rocky slopes, and small mangrove belts appear to be suitable breeding habitat for seabirds, but breeding has not been proven for any species.

Extremely rich and interesting is thereptile fauna comprising 19 out of 22 endemic species. Nesting of sea turtles, probably Green Turtles but possibly Hawksbills, takes place on the north coast. There is a major need for research of the invertebrates, which are mainly represented by a great variety of mollusks and arthropods. The habitat of the endemic fresh watercrab, Potamon socotrensis, is the numerous, mostly sporadic streams. Little is known on its biology, and the fresh water biota. It is still uncertain if there are true fresh water fishes on Socotra. Many insects show an adaptation to the island conditions by reduced wings. Scorpions belong to the few dangerous species.

Although Socotra is in broad biogeographical terms more closely linked with Africa, there are also interesting examples of relatives to Atlantic islands. Special investigations for each endemic species will be necessary to clarify the manner of speciation. Several areas on the island, notably the southern and western plateaus, the more isolated granite pinnacles as well as great parts of the coastal waters, have not been scientifically explored so far. There is a definite need for field surveys of any kind.

Besides all the bio-geological pecularities,the cultural history of human inhabitants on the island is equally interesting. The special language of the nomadic hill tribes, which have no writing, has its roots in the Mahra area on the southern Yemeni coast. Arabs, Africans, Greeks and Portuguese came to the island at different times and contributed their part to its own manners, culture, and religious ideas.

Another important special feature of Socotrais that, as a result of the vast isolation during the last decades,it is relatively little affected by human activities. Until now the whole island, with the exception of some areas in the more exploited coastal plains, is still dominated by a traditional balance between man and the environment, probably stable for more than 2000 years. For this reason Socotra island may very well be the best preserved semi-arid tropical island in the world.

Recent political changes have caused the opening of the island and have stimulated plans to improve living conditions and infrastructure. This marks a crucial turning point for this relatively untouched area. Without sufficient ecological monitoring and proper development "safety procedures," the delicate character of ecological balance will be affected, and any inappropriate development may, in due course lead to severe environmental damage, risking the survival of many of the endemic species. Of particular environmental concern are the direct impacts of planned development projects, such as an asphalt airport runway,a harbour jetty near Hadibu, and extended road infrastructure. Butit is also important to consider the significant environmental side-effects of inevitable socio-economic change.

The population of Socotra is estimated officially at 80,000, but is probably lower. The transhumant indigenous population of the interior is composed of subsistence farmers and pastoralists, while coastal dwellers engage mostly in fishing and trade. Socotra has lagged seriously behind the mainland of Yemen in economic development. The most important parts of the local economy are the production of livestock and coastal fishery. Anumber of families practice subsistence farming with small-scale production of fruits and vegetables (dates, cow peas, finger millet,sweet potatoes) for local consumption. But the harsh climate on Socotra restricts such cultivation to limited areas.

There are innumerable development problems facing the people of Socotra. Malaria, tuberculosis (95%) and dysentaria are well spread. Cholera may occur and infant mortalityis high (about 50%). Only one health clinic exists with basic equipment. For the only doctor, who is Socotri, often even essential drugs are not available. There are no paved roads on the island and electricity is only available for a few hours per day inthe larger villages. The overall percentage of illiteracy is 60 to 70%.

Despite these comparatively poor living conditions, principles of cooperation, self-help, and community labour are well established within all communities, and there is a whole range of relevant traditional rules and practices of ecological importance. These rules include regulations which control the cutting of live wood, forbid the use of other than dead wood as firewood, regulate grazing and the cutting of vegetation as fodder,and preserve the most important fruit bearing trees. Traditionally,the local people practice a rotational grazing. The practice of transplanting and/or sowing important plant species and protecting them from livestock while they grow is already in force. Local councils meet in the capital Hadibu at least once a year where major problems, including livestock management and development projects,are discussed.

How far the changes in the infrastructure and the availability of new sources of cash income will affect these traditional forms of land laws and the actual form of living together cannot be foreseen. There is a preliminary indication of rapid change in the vicinity of the larger settlements, such as Hadibo and Qalansiya, where traditional methods have already been modified. Even if there are no major impacts yet visible, it seems that wood gathering occurs more systematically and there are first signs of a waste problem induced by an increasing influx of goods. Life has already become more commercially oriented.

Altogether there are a great number of newproblems that the Socotri people are now faced with. The coastal waters around Socotra are abundantly stocked with fish. But this basic resource of the island is endangered by excessive fishing by larger boats from other areas. In reality the island and the mainland does not execute its territorial sovereignity over the water near the island. There is a completely uncontrolled collection of endemic organisms by individuals and foreign institutions, perhapsalso for commercial reasons in the case of pharmaceutical companies. Also unregulated mineral prospecting is occurring. All the effects of these activities are not yet clear, and even if there seems to belittle prospect for all the proposed development plans to be achieved in the immediate future, the danger for such a fragile island ecosystem is immense, especially by a further increase in private and uncontrolled enterprises.

The net-like character of arrangements canbe also outlined in relation to water. Nowadays the life in the settlements has been made more comfortable by a permanent water supply with the help of water cisterns in the mountains and an extended pipe system. By the introduction of pumps, it is also possible to truck water into otherwise waterless areas. But there are also a number of negative concomitants, such as the increase of mosquitos in freshwater ponds formed by leakage of water pipelines,the danger of disease through lack of control, and an increase in pollution and waste water. Very important from a long-term ecological point of view is the attraction of water cisterns for keeping larger grazing stocks than in the past. As yet there is no practical way to provide supplementary fodder, therefore drought and disease continue to provide their traditional control on livestock numbers. There are no exact data available, but the actual livestock numbers seems to be already clearly at the maximum levels that the water and vegetation can support. According to 1985 estimates, there were about 70,000goats, about 17,000 sheep, about 500 camels, and about 1800 cattle.

If livestock are enabled by water supply and importation of supplementary food to survive such droughts and consequently increase in number, or even if a disruption of the complicated patterns of seasonal livestock movement occurs, it can be expected that the present fragile equilibrium between vegetation, man and livestock will be destroyed very quickly. The vegetation has also a key role for holding the soil onto the slopes and reducing the surface runoff of water. Any removal of vegetation cover, which could be also forced by less control of the high demand of wood for various purposes, would result in accelerated soil erosion and the loss of surface water through increased runoff rates. This would result in a dangerous, inestimable spiral for the island.

Politically, Socotra is administered as apart of the Aden Governorate of the Republic of Yemen. The responsibility for wildlife conservation in the Republic of Yemenlies with the Ministry of Agriculture and with the Environmental Protection Council (EPC). Both have undertaken a variety of task ssetting up a frame for wildlife laws, a site protection system as well as environmental education activities. One of the most recent steps was a UNESCO fact-finding mission to Socotra at the end of1993. This mission examined the possibility of a Socotra Biosphere Reserve in order to combine development and protection for sustainable development.

At present there is no official conservation policy for Socotra. Many details on the most effective strategy are still unclear. The unique character makes Socotra a potential candidate for both designations, a natural World Heritage Site or aMAB Biosphere Reserve. But in practice the mere establishment and maintenance of large protected areas or nature reserves would not be sufficient for sustainable development. Potential sources for the islanders must be developed, such as a small-scale tourism, the cultivation and export of native plants, the collection and storageof seeds, and cutting for propagation within international programs.Further collection of information is needed, survey as well as monitoring. A stable research station in Hadibo, connected with a nursery and an arboretum, would be a very important step.

Socotra is a great chance and challenge forman kind, especially as there is fortunately still a welcome to the idea of a conservation strategy among the Socotri people. The island and the country need financial and scientific support to develop and to realise a research and management plan; but this should be done under the basic principle to utilise, as far as possible, local institutions already in place and to give the Socotri people the time and a realistic chance to choose a development path based on their traditional way of living.

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