Biomass appeal

Westport has surpassed itself this summer, gone riotously over the top in extravagant floral displays. Every reproduction Victorian lamp-post dangles a basket of petunias and lobelias; hundreds more hang from the walls or wedge into windowsills; whole facades are banked in multi-coloured blooms. The effect is aggressively cheerful and slightly surreal. One wonders who does the watering (and how) and whether the town might go on to hire ambulant accordionists, if not actual Bavarian yodellers.

Out in the Mayo countryside, nature has been trying to keep up. Such a gaudy profusion of flowers at the roadside: meadowsweet, loosestrife, montbretia, fuchsia, and now great yellow clumps of ragwort, buzzing with hoverflies.

Scientists have the word "biomass": the weight of everything that grows on any given unit of the earth's surface at any particular moment - not just the plants, but all the insects, animals and birds that are linked into the ecosystem. The biomass of Ireland's rural roadsides may have reached record levels this summer, with hot sun, regular showers, and rising global levels of carbon in the air.

Go back a generation, and much of this wayside verdure, "the long acre", would have been cropped by roaming cattle and sheep (which would then, I suppose, have to be weighed with the biomass). So, conceivably, many of the banks along our older roads have never looked lusher and more floriferous. This helps, a little, to make up for the loss of wildflowers and their insects in the rye-grass pastures beyond the ditch.

The new capital programme to give Ireland wider and faster roads will inevitably sweep away a lot of these linear, semi-natural margins, replacing their diversity and shelter, their irregular micro-habitats, with largely uniform verges and slopes. This new roadside estate will actually increase the amount of grassland removed from the business of farming.

And within the engineer's necessary matrix of sightlines and safety, there are abundant opportunities for creating new wildlife habitat that enriches both nature and the human traveller. After all, the verges are the most intimate edge of the landscape.

Already, many road authorities are using small native trees and shrubs to create a linear "woodland edge" that helps to screen roads and fit them into the landscape. In Connacht, the building of new stone walls should, in time, provide niches for ferns, mosses and lichens; even - without too much cement at the core - decent cavities for field-mice, wrens and stoats.

Grass embankments and verges can acquire their own diversity from wind-blown seed, or the germination of seeds long buried in the soil. Flushes of poppies, ox-eye daisies, or foxgloves along new motorways have been stirred up by the roadworks - even "lost" species like the cornflower have reappeared here and there. Mowing only the immediate verge and sightlines - British policy since 1975 - leaves room for all kinds of surprises.

Deliberate large-scale seeding with wildflowers is an expert affair, if the plants are not to be choked out by competitive grasses. Tough herbs like knapweed, cow parsley, common vetch often do well, and in damp places meadowsweet, ragged robin and devil's bit scabious, but the best results are often on the soils of lowest fertility.

Near my hometown - Brighton, in Sussex - wildflower seed that were sown into chalky soil along the city's by-pass took only three years to create an award-winning habitat for butterflies. Another English by-pass, in Cambridgeshire, has a colourful sward from early spring to late summer, using plants raised from native seed. In Ireland, the thin, limy soil of Co Clare has rewarded at least one school, seed-sowing project on a stretch of road embankment: cowslips seem a good bet in such a habitat.

Commercially-gathered native wildflower seed is costly to use on any scale, and a combination of expert guidance and amateur effort (harvesting, growing, planting) may be the best long-term formula for enriching the new grassy roadsides. Conservation Volunteers Ireland, which has promoted successful National Wildflower Weeks, seems ready-made for the role.

Now is also the time to set up a specialised team, recruited perhaps by Duchas, to service the environmental side of highway design - people who know about soils, water, sun-aspects, slopes, native plants, and trees, and can give their full time to design and execution.

So many good intentions occurring to road engineers seem to come to grief from the pressures on the ground. Old hedges vanish, old trees are smoothed out of the way, opportunities are lost for diversity, both visual and biological. Rain flows off the roads, for example: why not use it to make wayside wetlands and ponds?

And just how timid must we be about roadside trees, winter storms? Birches and rowans are beautiful; oaks, yews and beeches even better. I have been admiring a fine new publication from Northern Ireland, Our Remarkable Trees,* that celebrates the sense of place created by their leafy landmarks. Some of the best-loved trees are those that make road tunnels, trimmed by the passage of lorries - like the Dark Hedges, spectacular beeches near Mosside in Co Antrim, or the long stretch of trees at Tempo, Co Fermanagh, now protected by a preservation order. These don't, of course, flank six-lane highways - but, given the chance and looked after, assemblages of trees can become the most popular "public sculptures" of all.

Issues of this kind are the stuff of Terry O'Regan's National Landscape Forum, to be held next Thursday and Friday in St Patrick's College, Maynooth. There will be a score of speakers, among them an "ecotect", Paul Leech, giving the World Landscape Lecture on Thursday afternoon at 4.30p.m. Contact Landscape Alliance Ireland at 021-871460 or E-mail: .

* Compiled by Dinah Browne. Available from Conservation Volunteers Northern Ireland, Dendron Lodge, Clandeboye Estate, Bangor, Co Down, BT19 1RN