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Rare woodlouse at risk from St Helena’s quest to give us enough rope

Spiky Yellow Woodlice

The spiky yellow woodlouse: a population you could fit in a pint glass. Photograph: Phil Lambdon


Powered by article titled “Rare woodlouse at risk from St Helena’s quest to give us enough rope” was written by Robin McKie, for The Observer on Sunday 8th December 2013 00.05 UTC

On the flank of High Peak, one of the highest hills on the island of St Helena in the South Atlantic, there is a tiny scrap of land known as the Dell. The size of a tennis court, it is the island’s most important terrestrial habitat and one of the world’s most precious ecological niches.

The Dell is the last fragment of black cabbage tree woodland that once covered the island’s peaks. With its flat crowns of leathery leaves that form a dense, dark protective canopy, the black cabbage tree provides a warm, moist home for several local creatures, including the spiky yellow woodlouse, which is found nowhere else on the planet.

However, St Helena’s rugged slopes were largely stripped of black cabbage trees, which were chopped down to make way for the large-scale planting of flax, a plant that has sustained the island’s rope manufacturing companies, an industry that in turn reflects St Helena’s importance as a key stop-over for ships sailing to and from the far east via Cape Town.

Flax farming first devastated the black cabbage tree and in its wake threatens to destroy the spiky yellow woodlice that make their homes there. Only 50 or so survive. You could put the planet’s entire population in a beer glass. Unusually for woodlice, the spiky yellow does not feed on dead organic matter, or forage among leaf litter on the ground, but lives by clambering among fern fronds where it probably feeds on spores, scientists believe.

A worrying double whammy therefore threatens St Helena – the loss of its black cabbage tree woodland and the extinction of its spiky yellow woodlouse. (St Helena is a UK overseas territory, which makes the spiky yellow the most threatened British invertebrate.) It is a grim scenario.

There is hope, however. Thanks to support from the British government, conservationists say they believe they can save both trees and woodlice by building a large, shady canopy over the Dell.

“The Dell is situated on the south face of High Peak where it is exposed to gale-force winds for much of the year,” says Jonathan Hall of the RSPB, which has also been working to try to save the two species. “As the patch has shrunk, the foliage has been becoming less effective as a windbreak and the trees have gradually sustained damage.”

Last year, conservationists working for the St Helena National Trust discovered that storms had torn a large hole in the leafy canopy, exposing the humid air trapped below to the elements. This hole was temporarily patched up using shade netting, a move that proved highly effective. The Dell retained its humidity and plant growth directly underneath it improved. The woodlice also survived.

Now the trust and the RSPB have prepared plans to erect a permanent protective canopy at the Dell and a few weeks ago, the UK’s overseas territories environment and climate fund announced it would provide £37,000 of funding for it. In this way, both St Helena’s special patch of black cabbage trees and the spiky yellow woodlouse will be saved, it is hoped.

In addition, conservationists plan to take a few spiky yellow woodlice into captivity and attempt to breed them as an insurance policy against further loss of habitat on St Helena. “Hopefully, we will be able to save both this key fragment of woodland and the woodlouse,” said Hall. © Guardian News & Media Limited 2010

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