SPECIES DEPLETION IN UK – A THREAT TO BIODIVERSITY
In their study, of random 10km squares of land, the researchers found that a third of all species recorded have vanished from at least one of the squares they inhabited between 20 and 40 years ago.
The fate of butterflies is the most significant discovery, since experts had assumed that insects are more resistant than other creatures to habitat change, and insects also account for more than 50 per cent of all the Earths species.
But the new data show that the insects are dwindling at a faster rate than plants and birds, and have disappeared from an average 13 per cent of the areas they once occupied
They include two species that became extinct in the past 20 years, the large blue and the large tortoiseshell.
Writing in the journal Science today, the researchers said the findings lent support to the theory that the world is on the verge of “the sixth major extinction event in its history”.
Dr Jeremy Thomas, the director of the Natural Environment Research Council Center for Ecology and Hydrology, in Dorset, said: “There have been five big pulses in the past when over a very short period of time between 65 and 95 per cent of all species disappeared.
“No-ones saying were at that level of magnitude of species extinction yet, but we are saying that the level is dangerously high.
The great worry is that if this goes on for another 100 or 200 years, the cumulative effect may be to produce another of these mass extinction pulses. The difference this time around is that mankind will have caused it.”
The last, and best known, mass extinction occurred at the end of the Cretaceous period 65 million years ago, when the dinosaurs vanished from the Earth.
Todays new findings are based on a British record of observations made by thousands of amateur naturalists. The information they gathered, covering virtually every corner of England, Wales and Scotland, was carefully analyzed over the period of a year.
It encompassed all Britains 1,254 native species of vascular plants, all 201 native breeding bird species, and all 58 native breeding butterfly species.
Dr Thomas said there were a number of explanations for why human activity was threatening biodiversity, but it boiled down to “over-exploitation of natural resources”.
He was convinced that if a similar study were carried out in one of the worlds great rainforests, it would reveal even more shocking findings. The vast majority of insects, 90 per cent of which are thought to be still unidentified, inhabit the tropics.
A separate study, also published in Science today, showed how nitrogen pollution was damaging grassland in the UK.
The nitrogen, deposited from the atmosphere, originates from agricultural fertilizer and from burning fossil fuels.
Researchers led by Carly Stevens, of the Open University at Milton Keynes, estimated that grasslands might have lost more than 20 per cent of their species richness in the past 40 years as a result of nitrogen deposition.