How would your area score in the conservation ratings?

Like most of the hilly west coast, our hillside is striped into small farms, each with its original Land Commission lottery of good and bad land. Field banks stretch up from the shore to the mountain fence, carving up a palimpsest, a jigsaw, of human endeavour. Above the road the slope is still littered with immovable glacial rocks and veined with the hummocks of Neolithic walls. It is corduroyed with grassed-over lazybeds dug before the Famine and studded here and there with fallen gables.

Below the road and its ribbon of houses, old and new, most land is “improved”: the rocks cleared, the grass spread with fertiliser. Some fields have been ploughed and sowed with rye grass for a lusher crop of silage.

On the higher land, too, there are pastures green all year round and others, beside them, still thick with rushes and running with water; more still where spring grass lights the hollows between the old potato ridges.

Some of this, therefore, is “semi-natural grassland” – never ploughed and fertilised – and some of it, manifestly, is not. Add to this a raft of botanical distinctions between one patch of grassland and another – each with its mix, or “community”, of native plants, determined by different soils, moisture, altitude and so on – and the task of ranking grassland for its value to nature becomes challenging.

The first national survey of the Republic’s remaining semi-natural grassland is published by the National Parks and Wildlife Service. It took a team of four ecologists six years, between 2007 and 2012, to visit 1,192 sites across Ireland and study the plants in a total of 4,544 releves, or patches of standard size. These were then matched to 10 defined classes of habitat and scored for conservation value.

Most of the grassland was rather wet, as one might expect, but the habitats ranged from actual marshes and seasonal callows to the orchid-rich slopes of eskers and the flowery turf of limestone.

Diversity of species can be high at both ends and rather nondescript in the commoner middle, which is where I suspect our hillside belongs (though the forget-me-nots along the higher streams are rather nice).

The survey’s highest conservation score went to “Site 2704 Aughinish, Limerick”, a place I have never thought to go since Europe’s biggest alumina refinery, with its ponds of waste red mud, was built there. But apparently the island’s 400 hectares still leave room for a high diversity of grassland habitats, including two in the top list of European rarities, plus stands of the red-bobbled greater burnet and other plants of distinction.

The team worry that many of their top 50 sites have no special protection against the ploughing and reseeding that smothers native grasses and wildflowers. But, they report, almost as serious is the decline of small farming and the abandonment of land.

Grassland needs grazing or it changes its vegetation, and the team found “large tracts of rank, unmanaged fields, particularly of wet grassland, many with encroaching scrub. Land that has been abandoned becomes too rank even for many bird and insect species to frequent it.”

Ironically, some of the abandonment is due not to old age or emigration but to measures to conserve biodiversity.

Seeing land thick with coarse grasses, weeds and rushes, with willow and blackthorn creeping in from the ditch, the team found farmers who, responding to the Rural Environment Protection Scheme, had set the fields aside as a habitat for wildlife – “for the birds”. Some actually wanted more wildlife.

This touches on a strong debate about ecological restoration. Should the aim be to preserve the plant communities of semi-natural grassland at a particular point in land history, by continually grazing or mowing (to perpetuate, say, an erratic, if beautiful, growth of orchids)? Or should protection let nature go its own way, working through the botanical succession that ends up with far fewer species under a tangle of trees?

Botanical “rewilding” is the aim of Green Sod Ireland, a charity founded in 2007 to conserve “wild acres” of gifted land – “a celebration of the overgrown, the hidden, the weed and the bramble, where species thrive”. It looks not only to the countryside but also to protecting or creating wild and weedy plots on urban housing estates. It will promote its ideas on walks for Earth Day, on April 22nd.

Along with land in Carlow, Green Sod Ireland has apparently been given five or six hectares of land at Salruck, at Little Killary, across the bay from me in Connemara. A lovely, semi-natural corner, indeed, and for a time a contemplative haven for Ludwig Wittgenstein. He too, I gather, thought that nature owes us nothing but itself.