ANOTHER LIFE: The farm at the end of the duach was derelict and unfenced for many decades, the land absorbed into the sheep-grazed commonage along the shore. It is, in farming terms, scarcely land at all - a brief apron of sandy machair grass around high creggans of rock and ravens' cliffs; little, soggy valleys ridged with ancient lazy-beds; a reedy lake for sea-fishing otters to wash the salt from their fur, writes Michael Viney.
A couple of years ago, a courageous neighbour bought the farm and fenced it off as a nature reserve, the sheep progressively ushered out into the commonage proper. This is the first summer without any grazing at all and the result is a revelation. On one side of the fence, a worn, green billiard table littered with black balls of sheep dung; on the other, a soft Persian carpet glowing with life and colour.
For the first time in a generation, the plants of the machair, naturally low and wind-dwarfed, have been allowed to flower without being bitten off or trampled on. The grasses alone are a picture: a shimmer of foxtail and feathery fescue, pink and cream. Among them, the brilliant summer flowers we should expect on the sandy machair: bird's-foot trefoil, self-heal, eyebright, lady's bedstraw, red clover, wild thyme in fragrant purple drifts. And on the high, boggy slopes, bristling with darkly flowering sedges, are orchids in their hundreds, fading from an early splendour of purple, pink and white.
As a purely visual pleasure, this transformation of the land is something that slows one down, just to look, so that larks wait in hiding, only springing up at the last, soft footfall. It also, no doubt, has all kinds of ecological promise, to do with insect enrichment, plant succession, the security of birds and mammals, but for the moment it is simply an immediate, enchanting example of biodiversity in bloom.
Such pleasure is probably the least important reason why biodiversity is a good thing: human survival is more to the point.
Conservationists insist that biodiversity is basic to the Earth's life-support system and that the progressive loss of species - as in the current destruction of natural forest - could help destabilise the very processes by which the planet services our presence and wellbeing.
Most ecologists, probably, go along with the idea that every species matters. Like rivets in an aeroplane, each has its own, small importance: let too many pop and things start to fly apart. But some are now arguing that since so many species seem to do much the same job, mere "species richness" may not be essential: so long as "keystone species" are identified and cared for, their ecosystems will probably still function.
As much as half the planet's biotic diversity, by respectable estimate, will be lost in the next century as a direct result of human activity, and many powerful decision-makers would be reassured to hear that many species are redundant anyway.
As UCD zoologist Dr Tom Bolger wrote in a recent review: "At the moment, policy makers only want to know how many species we can afford to lose." He and his UCD colleagues have joined an EU project called BioAssess to find tools for monitoring change in biodiversity. These will be tested in Ireland and elsewhere to measure the impact of farming and forestry on different groups of plants and animals.
The UCD team is also involved, along with the University of Limerick and Teagasc, in Agri-Biota, a project funded by the Environmental Protection Agency. Beginning in the autumn, six Ph.D. research students will be studying the impact of farming on earthworms, beetles, birds and other creatures, and how more species of plant can be brought into the current rye-grass monocultures of farm grassland.
The organisms of the soil, in their teeming variety, are the very foundation of most ecosystem processes, essential to soil structure and the recycling of nutrients for new plant growth. Study of Ireland's 26 kinds of earthworm finds each species with its own body size, feeding behaviour and food preferences, its own level and burrowing behaviour in the soil, its own survival strategies.
How much they all matter has been dramatically suggested this year by the failure of half the potato crop through soil waterlogging and associated disease. Research by the UCD team shows that the intensive mechanical cultivation, de-stoning and harvesting operations in potato-growing can lead to a virtual elimination of earthworms.
In one field, the number of earthworms was reduced from more than 1,100 to 54 per square metre after a single potato cropping season and to a scant four worms per square metre in the following year. In the same period, the number of earthworm species in the soil fell from nine to five and finally to one. The team were alarmed to find no recovery of the earthworm populations during two succeeding years under cereals.
For other invertebrates, such as beetles, farming has winnowed down the species to simple groups that can survive in cultivated fields through flexible lifestyles and high mobility. Beetles, predators often valuable to farming, need uncultivated field margins in which to spend the winter.
Gentler rotations, less intensive grass cutting and grazing, more variety in field pattern - all would help support the overall biodiversity.
In line with our modest island ration of different species of flora and fauna, it has been assumed Ireland probably had relatively few species in most groups of soil animals. This may not be so, the UCD team says: new species are being found all the time, and when little-studied habitats (such as coastal pasture) are explored, we may have a bigger range than we expected.
But the real surprise about this research is to realise how long we have had to wait for it; 50 years after the great onset of change from the hey-day of Ireland's mixed farming - a golden age, surely, of biodiversity - we have come to the time when we need to know what intensive farming does to the natural life of the soil.