St Helena Online

Tag: invasive species

Ascension’s fake forest is a challenge to science, says writer

Sir Joseph Hooker planted tree on Green Mountain to trap clouds and rain. It worked
Sir Joseph Hooker planted trees on Green Mountain to trap clouds and rain. It worked

When the Royal Navy first “invaded” Ascension Island, it did so not with weapons of war, but with plants – creating what is said to be the only man-made tropical forest in the world.

The result is either a beacon for re-greening the planet, or a biological abomination, says writer Fred Pearce on the Yale Environment 360 website.

Isolation has meant Green Mountain has been “badly under-researched”, he writes – but it is now being hailed as a reason to look again at established thinking on the environment.

Because it works.

Bermuda cedar, Chinese ginger, Cape yew and Brazilian guava trees thrive on Green Mountain, alongside Japanese cherry trees and Madagascan periwinkles – and screw pines that grow higher on Ascension than they do on their native Pacific islands.

On St Helena, they’re following conventional practice by grubbing out alien species that threaten the survival of endemic plants.

If conservation officer Stedson Stroud took that approach on Ascension, there’d be almost nothing left. But actually, he says, some native ferns are growing on introduced species, and faring better because of it.

Three others, though, are believed extinct. A fourth was rediscovered by Stedson himself, and is now being propagated at Kew Gardens in London, ready to be reintroduced.

Green Mountain’s unnatural success is creating controversy among ecologists, says Fred Pearce.

He asks: “What are we to make of this confected cloud forest? Is it nature or a garden? Is it a beacon for re-greening the planet or a biological abomination?

“The British government’s environmental policy for the island is the ‘control and eradication of invasive species’ in order to ‘ensure the protection and restoration of key habitats’.

“But the policy has nothing to say about the protection of — or even ecological research into — the extraordinary novel ecosystem in their midst on which the indigenous species often depend.”

Click here to read the full article on the Yale Environment 360 website, published by Yale University.

Climate change puts UK territories in danger, warns minister

Climate change is jeopardising the future of some of Britain’s overseas territories and could leave islands ‘completely cut off,’ a UK government report has warned.

Environment Secretary Caroline Spelman says in the report: ‘The environmental challenges which our overseas territories face are… threatening the future security and safety of our territories, and in particular the people and the biodiversity that they support.’

Research says small island territories are ‘virtually certain to experience the most severe ecological impacts’ of climate change, including heat waves, heavy rain and storm surges.

The report adds: ‘Some islands could be completely cut off from communication with the outside world owing to their remoteness, potential impacts of sea-level rise and more intense storms, including damage to infrastructure such as ports, harbours, airport structures and facilities.

‘There could also be significant health impacts arising from both sea-level rise and extreme weather events.’

Threats identified by the Department for Environment, Food and Rural Affairs  (DEFRA)  include:

  • Invasive alien species, which harmed St Helena’s last bastard gumwood tree
  • Loss of habitats
  • Problems coping with waste, including on Tristan da Cunha
  • Damage to nature from tourism
  • Economic damage from alien species, on land and in the sea.

‘Tourism is important to the local economy of the UKOTs,’ says the report, ‘but can also deplete and damage local natural resources.

‘It is also intrinsically linked with development to serve the needs of tourists, and development pressures can result in negative changes in land use.’

The report has been published ahead of a White Paper – due early in 2012 – bringing together the policies of the three government departments responsible for overseas territories.

It sets out the support given by DEFRA to protect the environment in the territories, including the 340 species that are found nowhere else in the world – many of them endangered lists.

‘The risks of not considering the value of the natural environment in decision-making may lead to unsustainable economies,’ says the report.

‘Not considering environmental issues such as climate change could lead to security and safety issues.’

Research is taking place on the threat of non-native plants in the Falkland Islands. ‘There are now more introduced plants than native plants in the Falkland Islands. Thistles and ragwort species are examples of competitive invaders that have been introduced deliberately or accidentally through trade, tourism and travel.’

Horses can die from eating ragwort.

Projects on St Helena included efforts to capture seeds from the last surviving bastard gumwood tree. Mass planting may save it from extinction.

Alien marine species – a serious threat to fisheries – are to be investigated in waters around South Georgia, the Falklands and Tristan da Cunha.

The report also says money is to be spent attacking ‘high priority invasive alien species’ – including rats – in the Falklands, Ascension and St Helena.

Read the full report, with details of projects in all the overseas territories, here.