AFTER three days and nights cramped on a shark fishing dhow in the middle of the Indian Ocean, with little to do but eat seafood and contemplate the next tropical storm, the sight of Socotra comes as a welcome relief. At first it is just a wisp of cloud on the horizon. A few hours later and the hazy outline of the island comes into view. Closer still and you are nearing the main settlement of Hadiboh, a parched town of squat stone houses set against towering granite mountains blanketed in cloud. It is then that you first glimpse some of Socotra’s bizarre and beautiful plants – cucumber trees shining in the sun on the foothills of the mountains, and along the jagged skyline the mushroom-shaped silhouettes of Socotra’s most famous plant, the dragon’s blood tree (see Map).
This scene has changed little since the first scientific expedition in 1880. And the same skyline would have greeted the British botanist Quentin Cronk who “rediscovered” Socotra ten years ago. Scientists hadn’t set foot on the island in two decades believing mistakenly that the environment had been destroyed by overgrazing. In fact, lack of development means that Socotra is much as it would have been in prehistoric times. “Socotra is one of the few dry, tropical islands left which is still relatively untouched by modern development,” says Alan Hamilton of the World Wide Fund for Nature. “It represents a particular type of gene pool, not really found elsewhere – a bit like an Indian Ocean version of the Galápagos.”
Isolation is the key to Socotra’s pristine environment. It is only 240 kilometres from the Horn of Africa, but because high winds and seas cut the island off for five months of the year, it is one of the most inaccessible places on Earth. Of the 850 plant species on Socotra, over a third are unique. Many of these endemic species are remnants of ancient floras which long ago disappeared from the African-Arabian mainland. This weird vegetation makes Socotra the tenth richest island in the world in terms of endemic plant species says the World Conservation Monitoring Centre.
Advertisement
Biologists find islands such as Socotra irresistible because they are “living laboratories” for the study of evolution and ecology. Islands represent a small part of the Earth’s land area but a large part of its biodiversity, including about one-sixth of the total flora, so they are critical to global conservation. But these floras are particularly susceptible to extinction. For a start, they often cannot compete with weedy plants brought in from outside. And because they usually evolve in the absence of large grazing animals most of these plants lack anti-grazing defences such as thorns or poisons and are killed by livestock.
Socotra’s rare species have escaped this fate. Relics of ancient species are so abundant that the island looks like most people’s idea of a prehistoric world. Until at least 10 million years ago Socotra was part of the African mainland and, before that, part of the African-Arabian tectonic plate. Today the ancestors of plants from these ancient landmasses can still be found growing on the island.
Perhaps the most strikingly primitive plant is the dragon’s blood tree (Dracaena cinnabari), sometimes called the “inside-out umbrella tree” because of its strange shape. Its nearest relative is the dragon’s blood tree of the Canary Islands, also a relic of an ancient flora. Twenty million years ago the trees stretched from the Canaries, through the Mediterranean region to Southern Russia.
Legend has it that the tree sprung up from congealed blood shed by a dragon and an elephant as they fought to the death. Cinnabar, the crimson red resin from the tree’s leaves and bark, was highly prized in the ancient world. It was used as a pigment in paint, for treating dysentery and burns, fastening loose teeth, enhancing the colour of precious stones and staining glass, marble and the wood for Italian violins. Although it no longer has a commercial value, cinnabar is an important resource for the 40 000 people who live on Socotra. They use it to cure stomach problems, dye wool, glue pottery, freshen breath, decorate pottery and houses and even as lipstick.
Many other Socotran plants are descendants of ancient species which have adapted to their new island environment. A varied landscape of semi-desert coastal plains, limestone hills and granite mountains, together with an extreme climate of low rainfall and hot summer winds of up to 70 miles per hour, create countless ecological niches and explain the wealth of endemic plants. Often these are restricted to highly localised habitats. The rugged granite pinnacles of the Hagghier mountains, which rise to over 1500 metres and dominate the Socotran skyline, are a prime site. Heavy cloud hangs over the pinnacles during winter – hence Socotra’s ancient name of “Isle of Mists” – bringing much-needed moisture to the pinnacle plants. The wealth of unique plants here include a species of woody cabbage (Hemicrambe townsendii) whose nearest relative is on the other side of Africa, in Morocco. New species are uncovered on every trip to the pinnacles, which are surrounded by almost impenetrable vegetation.
Below, on the rocky, exposed ridges and sheltered valleys of the limestone plateau grow exotic succulent trees. These include the Socotran fig (Dorstenia gigas) and the desert rose (Adenium obesum subsp. sokotranum). Their swollen bottle-shaped trunks keep the trees supplied with water during the summer droughts. Other plants in this habitat, such as a relative of the bluebell (Ledebouria grandifolia) – recently discovered in flower for the first time – cope with summer drought by hiding underground as bulbs until the rains begin.
Socotra sports examples of gigantism – a curious phenomenon of island evolution. Until 10 million years ago, when the island was still part of Africa, any broad-trunked trees would have been destroyed by large herbivores like elephants and rhinoceroses. When Socotra broke away the absence of such herbivores and trees left a new ecological niche into which herbs and shrubs could grow, and grow. The most startling example of gigantism is the cucumber tree (Dendrosicyos socotrana), found on the coastal plain. Most other members of the cucumber family are climbing plants or shrubs, but their Socotran cousin is a tree, up to four metres high with a bottle-shaped trunk and cucumbers hanging from its branches.
Socotra has been famous for its botanical riches for hundreds of years. As well as cinnabar, other products exported to the ancient Mediterranean region included resins of the local frankincense (Boswellia) and myrrh (Commiphora) trees, used in medicines and rituals, and the juice of the native bitter aloe (Aloe perryi), used as a purgative. By the 19th century news of Socotra’s rich flora had reached the British Association for the Advancement of Science in London. In 1880 the Association launched the first ever scientific expedition to the island, led by the Scottish botanist Isaac Bayley Balfour who put Socotra on the map. In seven weeks Balfour collected more than 500 plant species, over 200 of which were new to science. But by 1967 a group of British botanists visiting the island came away believing that most species faced imminent extinction from increasing human activity. If unchecked, goat-grazing and wood-cutting would rapidly destroy the natural vegetation. So many botanists gave up hope for the flora and visits to the island dropped.
Then in 1985 the island botanist Quentin Cronk resurveyed Socotra and found that the predictions of earlier scientists had been too pessimistic. Although there were still large herds of livestock and extensive wood-cutting, the environment was largely unspoilt. “Having seen the degradation overgrazing can cause,” says Cronk, “I was staggered to come across a place which was in all probability substantially the same now as 1000 years ago.” His discovery revived international scientific interest in Socotra. Specialists in Arabian flora have found many new species and traced almost all the previously recorded flora, including the only Socotran plant officially recorded as extinct by the World Conservation Union, the pink-flowered shrub, Taverniera sericophylla.
So why did Socotra’s plants survive when the flora of many other islands have been destroyed by development? Socotra’s inaccessibility is one factor. Until recently there were just two weekly flights from Yemen to the airstrip outside Hadiboh – now even these have been suspended. Without an influx of people and technologies the Socotrans have had to use and protect their natural resources. They live by fishing, herding livestock, date cultivation and gathering plant products – a lifestyle that has changed little since the first settlers arrived over 2000 years ago. There are no ports, proper roads, or sewerage facilities on the island, and Hadiboh has electricity for only a few hours a day.
With very little in the way of modern building materials and medicines, wild plant products are crucial to the survival of the Socotran people. So much so that they have developed a system for preventing over-exploitation of the island flora. These rules are enforced by a network of tribal elders who control, for example, the cutting of live trees and shrubs. The tribal elders also ensure that livestock are moved from one area to another to prevent overgrazing.
But just because the flora has survived until now, doesn’t mean there is any room for complacency. Even with built-in safeguards, the balance between islanders and their environment is precarious. The problem is that Socotra’s people are increasingly calling for the benefits that development would bring. Famine used to claim many lives during each summer drought – imports of milk powder, flour, cooking oil and rice, which began in the early 1970s, have largely put an end to that. But malaria and tuberculosis are still widespread and the infant mortality rate is 131 per 1000 – one of the highest in the world.
Better life
Miranda Morris, an ethnographer from St Andrews in Scotland, is one of a handful of Westerners to speak Socotran. She has visited the island several times to research its culture, and confirms that Socotrans want development. Many have relatives enjoying a better life in the Arabian Gulf. They say they want improved communications with the mainland, better healthcare and water distribution and imports of subsidised building materials to conserve trees on the island. Most importantly, they want a harbour that can be used in all weathers and freezer facilities so that they can earn a proper living from their fishing – the waters around the Socotran archipelago contain some of the richest fish stocks in the Indian Ocean. But Socotrans also recognise the dangers of uncontrolled development, particularly overgrazing. The people, says Morris, have “a clear understanding of the value to them of preserving the equilibrium between human and livestock numbers on the one hand, and the vegetation on the other”. But is it possible to meet the needs of the islanders and still preserve Socotra’s unique botanical heritage?
Development is certainly on the cards. Socotra is part of Yemen, and the government there has long-standing plans for the island. But action has been delayed by a lack of financial and other resources. The country has also been involved in a year-long civil war. Now, however, there is a new government keen to improve conditions on the island. This time the Yemeni government has joined forces with the United Nations Development Programme and put together a five-year conservation programme. If it goes ahead, it will be the first step towards giving Socotrans the development they want. First, however, Yemen must ratify the Convention on Biodiversity so that it can submit the programme to the Global Environment Facility (GEF), an international organisation that helps finance environmental projects. Ratification is imminent and there is a good chance the programme will be accepted. Eventually, it could get backing from British Gas. The company, which is currently looking for hydrocarbons off the coast of Socotra, has agreed to assist the conservation programme if exploration is successful.
The programme is good news for plants because it proposes research into natural ways to regenerate endangered species and the establishment of a nursery where seedlings can be grown before reintroducing them into the wild. If the programme goes ahead there will also be a survey to see how widespread and effective traditional land management practices are, as well as research to assess how changes in vegetation might affect people and their livestock. Experiences elsewhere have shown that ethnobotanical knowledge is one of the first casualties of modern development, so Socotra’s programme is to include a plan to list local plant uses.
Field guide
A common problem for conservationists is the lack of comprehensive and user-friendly information on the plants they are trying to save. So botanists familiar with Socotra’s flora are collaborating with Morris to prepare a field guide to plants and their traditional uses which they hope will serve as a model for conservation work elsewhere. At its centre is an illustrated plant identification key with cross-references to details on botany, ecology, and ethnobotany. The information will also be fed into a database, which will allow the project to analyse changing plant distributions and predict the impact of future development.
The GEF programme aims to build on the network of local village councils, and employ Socotrans in every aspect of the project. Some will train as guide naturalists to provide tours for the increased number of Yemenis who want to study botany, ecology and conservation in the region. Local people may also be involved in efforts to bring healthcare to highland communities and to put traditional medicine on a firmer footing by opening a pharmacy in Hadiboh. Perhaps most importantly, the project will screen products from certain endemic species for possible commercialisation abroad, as dyes, resins, gums and medicines.
With these plans comes renewed optimism for the future of Socotra. Development seems inevitable, and a sensitive approach could raise living standards for the people while preserving the unique plants that are their most important natural resource. If the programme does work it will be a rare success story for island conservation. If it fails, uncontrolled development could turn this fragile environment into a desert within a few decades.
Island lives
THE number of endemic plant species on an island depends on its age, size, topography, climate, degree of isolation and geological history. The Canary Islands, for example, are home to over 500 endemic species – 40 per cent of the flora. But Britain, which is over 30 times bigger, has only about 16 endemic plants – less than 1 per cent of the flora – according to figures from the World Conservation Union (IUCN). The reasons for this difference include the Canaries’ more diverse topography and warmer climate, and the fact that the islands have not experienced glaciations and have been isolated from the mainland for many more millions of years than Britain.
Broadly there are three types of island endemics – relict species, newly adapted species and adapted-relict species. Relict species are found on islands which, like Socotra, were once part of larger landmasses but have become isolated through continental drift and changes in sea level. The species may die out on the mainland, leaving remnants of once widespread ancient floras on the island. Most of the plants of Madagascar and New Caledonia are relicts.
Newly adapted species are the product of accidental colonisation of an island by individual plants, which then adapt to the new environment. This type of endemic is commonly found on islands which have never been part of larger landmasses and are volcanic in origin, such as the Galápagos and Hawaiian Islands. The third type of island endemic, adapted-relict species is the result of a second burst of evolution in the relict species.
Today, island endemics make up a third of the world’s threatened plants, and many are already extinct. On Saint Helena, alone, 96 per cent of the endemic flora is rare or threatened with extinction, says the IUCN. Seven endemic species are definitely extinct and another 50 or more are believed to have been wiped out since the introduction of goats in the 16th century.