Let ecology lead in landscape design

Another Life: A population getting on for eight million, some four million houses on the island and the same number of cars - there were frightening figures in A Vision of Transport in Ireland in 2050 published by the Irish Academy of Engineering a couple of years ago.

A whole new national grid of motorways, of course: automated roads, on which your car will be driven for you by a great, all-knowing, national roads computer.

So relax and look out the window - but then the engineers' 60-page vision hits a blind spot.

Apart from an assumption that, by 2050, "planning policy has been successful in protecting precious landscape", it offers little conjecture on what you might actually see. It's just as well, perhaps, that the National Roads Authority (NRA) is jumping in to reassure us.

At its conference on Building a Better Roads Environment in Croke Park next Friday, delegates will be promised a view of the countryside that will still please the eye at 120 kph.

The solution, set out in new Guidelines on Landscape Treatments for National Roads in Ireland, is something called "dynamic scale", which is roadside landscaping matched to the angle and speed that decide what a driver can focus on. Small clumps of shrubs, subtle changes in vegetation, narrow vistas, just won't register. On the other hand, long belts of same-looking trees or crudely repetitive clumps can lead to "a loss of perceived naturalness, and may contribute to driver monotony and fatigue". As with nature itself, diversity is all.

In a conference that may otherwise be haunted by the wailing ghosts of Tara, the guidelines are potentially some of the best PR the NRA could present in "mitigation" - its own word - of its impact on the landscape. The notion of a countryside of virtual reality, existing only in the driver's eye, is marginal to ecological landscape design that serves nature and biodiversity.

Gone is the roads engineer as park-keeper, and horticultural landscaping that looks to herbicides and fertiliser to keep ornamental verges in order. The new approach will create low-input, self-sustaining habitats that look - and are - more natural and even save money in the process.

A lead author of the guidelines, Lisa Dolan, has spent five postgraduate years at UCC, researching a PhD in road ecology. Invited by the NRA to demonstrate her ideas on a new stretch of road beside Ballyseedy Wood, near Tralee in Co Kerry, she created roadside ponds with run-off water, planted them with relocated alder, recycled young oaks to make a little wood, used willow cuttings to make new hedges and created semi-natural grassland with local hayseed. By using natural resources and doing without costly horticultural inputs, she saved one quarter of her budget from the NRA.

The key ingredients of the change are basic, indeed: native seeds and an understanding of different soils. Like many home gardeners who try to create "wild meadows" from lawns, roadmakers have been slow to learn that farmland topsoil, over-enriched and full of dock and thistle seeds and agricultural grasses, makes rank and ugly roadsides.

To create a semi-natural grassland, full of native herbs and wildflowers and shimmering with butterflies, what's needed is the subsoil. This often erupts with long-buried glories of its own - corn poppies, foxgloves, ox-eye daisies, yarrow. Sowing it with native grass species - fescues and bents - will leave room for natural colonisation (even orchids, with luck).

Strewing it with hay from local semi- natural grassland will further enrich the flora, and all in ways that need no fertiliser, no herbicide, and only one mowing in the year.

The insistence on native seed runs to trees and shrubs as well, for the massive "land take" of our new motorways offers options for linear native woodland (which can, indeed, use the rich farm topsoil). Since roads are planned several years in advance, landscape contractors appointed early will have time to grow the stock they need (no alien sycamores, which seems a pity, but the species can be recklessly invasive in the long term).

The 160 pages of the guideline document are full of concern for restoring disturbed habitats, reconnecting broken wildlife corridors and, in general, "adding a new ecosystem to the landscape". There are heartening examples of things already done as "compensation" for the wounds of road-building: a new brackish intertidal marsh beside the Youghal by-pass in Co Cork, a new wetland at Kilmacanogue, Co Wicklow, created with sods and plants disturbed along the road.

The NRA is the nation's biggest procurer of landscape works. New industries building on greenfield sites are not far behind. By letting ecology lead in landscape design, they could both create replacement room for nature in an increasingly crowded island. The new guidelines in draft form can be downloaded from www.nra.ie/environment.