Ascension’s scientific connections

October 19, 2015


Ascension is celebrating its bicentenary.  On Saturday a Royal Marine band will play and there will be fireworks to celebrate the two hundredth anniversary of two naval captains claiming the south Atlantic staging post for George III.  The garrison was placed there to prevent any expedition by the French to rescue Napoleon, who had been exiled to St Helena to the south after the battle of Waterloo, but the marines stayed to support the trade route to India and to support the British navy in its efforts to crack down on slavery.  A tiny park has been created to mark the anniversary of the start of British rule in the centre of Georgetown, the capital, on the cinder-covered cricket ground in front of the former Exiles Club.

Early visitors to the island at the beginning of the 19th century describe it as exceptionally barren with very few plants.  The island is volcanic, relatively young at about a million years old and its hills are mostly covered with reddish brown cinders.  It has no rivers, streams or lakes and so early sailors thought it had no water – indeed the earliest recorded sailor to be exiled there in the 17th century went slowly mad after drinking turtle blood and eating salty fish, to judge from the diary he left behind.  The marines found a well, high up on what is now called Green Mountain.  When Charles Darwin arrived in 1836 he admired the “active industry’ on the island on which the marines had established a garden to supply vegetables and fruit for the garrison.  But he did observe that the island was “destitute of trees.”

The lush tropical forest that now covers the top of Green Mountain, 2817ft, was the idea of Sir Joseph Hooker, a close friend of Darwin and later director of the Royal Botanic Gardens at Kew.  Hooker, an assistant surgeon on Sir James Clark Ross’s expedition to map Antarctica in 1839-43, suggested that planting trees would increase rainfall and prevent soil erosion.  There followed a mass planting of organised forests, shrublands and pastures on the island as well as a wide variety of crops, including bananas.  Tall pines were grown for replacement masts and spars.  In all some 220 exotic species were introduced by the navy from different parts of the world.  Kew Gardens alone sent over 330 plant specimens.  The marines even kept a farm and milked cows.  The hillsides were concreted in places as a water catchment area and the water eventually piped down to Georgetown in a series of iron pipes, now largely disused though they still supply the Administrator’s residence high up on the mountain.

The plants competed with the native flora, mostly ferns, mosses and lichens, and only the fittest survived.  Today the summit of Green Mountain, now a national park, is covered with a forest of bamboo which drips with water from the clouds which form around it.  Records do not appear to show that rainfall has increased as Hooker believed it would.  But the mountain’s introduced “cloud forest” does appear to capture water.  It stands both as a great early example of bio-engineering and an example of a man-made experiment that has endangered the island’s native and endemic plant species, such as the Ascension island parsley fern, rediscovered in 2009.  The fern was sent back to Kew to be propagated and has returned to be planted out.

As scientists begin to work out what they have found on our deep-water survey of Ascension on the British Antarctic Survey’s icebreaker the James Clark Ross, another great scientific project is under discussion, the protection of Ascension’s abundant marine life in a reserve.  Scientists will be drawn upon to pronounce how big a reserve would be necessary to protect the extraordinary profusion of fish and other marine life in Ascension’s waters.  The Ascension Island Government will have to decide whether they can afford, with some outside help, to impose enforcement measures to protect a core area from the world’s long-line tuna fleets.  The decisions that will shortly be taken are likely to have consequences every bit as lasting as those taken by Joseph Hooker nearly 200 years ago.

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