Science: Live the high life and save the wildlife: Markets for cork and pork are keeping alive ecologically sensitive areas of Spain and Portugal. Malcolm Smith reports

In the pavement cafes of Olivenza, a village in western Spain, nothing is more delightful than to while away a balmy spring evening with a glass of rioja and a few slices of jamon iberico.

But who would imagine that eating the delicious local ham and drinking Spanish wine is a personal - and highly pleasurable - contribution to conserving one of Europe's richest and most extensive wildlife habitats?

The dehesas of Spain (montados in Portugal) are huge areas of scattered evergreen cork oak and holm-oak trees growing over flowery grassland, scrub and cereals. Covering more than 4 million hectares in Spain alone (the largest area is in Extremadura in the west), they are home to several of Europe's most impressive species, including Spanish imperial eagles, black storks, wolves and lynx.

Their conservation depends utterly on retaining land management practices that are centuries old. Producing cork, mostly for wine bottles, and grazing Iberian pigs for their ham are vital components of that management. If the markets for these products were to decline, the very existence of the dehesas and their wildlife would be severely threatened.

On a warm spring day, the richness of the dehesas is immediately evident. Butterflies flutter between blue irises, deep red French lavender and white flax; the calls of the amazing cinnamon pink, black and white hoopoes, which nest in tree cavities, never cease. Small groups of multicoloured bee-eaters come past, chasing airborne insects above the trees. And azure-winged magpies - found only here and in China - interrupt their bubbling flight calls with hoarse screams as they glide from tree to tree.

In winter, the dehesas harbour millions of small birds, many of them breeders from northern Europe. Blackcaps, tits, thrushes, chiffchaffs, robins and wood pigeons are just some. Densities of around six per hectare are commonplace.

But it is for some large species, including birds of prey, that this landscape is renowned. According to BirdLife International/European Bird Census Council, up to 50,000 cranes winter in the dehesas, feeding on acorns and scatterings of cereal grain. Black vultures, which are globally threatened, breed in wooded mountains but hunt over the dehesas for dead animals. Spanish imperial eagles - the whole world population of 160 pairs breeds in Spain - do the same, but take mainly live rabbits and hares.

Black kites abound; there are buzzard-sized booted eagles, golden eagles and, in places, the huge eagle owl. Black and white Egyptian vultures search for carrion and the dainty, mainly pale grey, black-shouldered kite, associated more with the African savannah than the Spanish plains and dehesas, hunt smaller prey. Short-toed eagles specialise in taking reptiles such as sand lizards, grass snakes and tree-living ladder snakes.

In the wild mountain forests of Extremadura roam eight or nine packs of wolves, which descend sometimes to hunt in the dehesas. So, occasionally, do wildcat, lynx and European genet, a small long-tailed, spotted, cat-like mammal sacred to the ancient Egyptians.

Cork oaks are stripped of their thick bark by hand in late summer, a process that can be repeated, because it regrows, at least every decade. The holm-oaks are lopped in winter for charcoal-making and fodder for livestock. Careful cutting, a skill which is dying out in some places, prolongs the life of the trees, creates a spreading crown to provide summer shade for protecting the undergrowth and livestock, and encourages the production of larger acorns. The oaks are vital for the well-being of the dehesas. They help to retain a stable water table and nourish the poor soils with their leaf fall.

But traditions are breaking down. According to Mario Diaz, Professor of Biology at Madrid's Complutense University and an expert on dehesas, transhumance - driving cattle to the hills for summer and winter in the dehesas - is now much less commonplace. Many herds are kept all year among the trees, overgrazing some of the vegetation and preventing new oaks from growing up. Dr Diaz believes this to be the greatest problem the area now faces.

A worse threat, however, is now receding. Over the past few decades large areas of dehesa have been cleared to grow intensively managed crops of maize or strawberries - much of it funded by the EU and the Spanish government. These require expensive irrigation schemes and many farmers and their unions are beginning to question the economics of such schemes.

Clearance to grow eucalyptus plantations - now acknowledged as a failure in timber and economic terms - has ceased, but only after hundreds of thousands of hectares had been bulldozed. The planting has caused serious soil erosion.

Other areas of dehesa are left unmanaged, often because of difficult terrain. 'So the dehesa is replaced,' says Dr Diaz, 'with cistus (white flowering rock rose), arbutus (strawberry tree) and other shrubs which form maquis (a thicket of scrub).' A variety of trees grow through, eventually converting dehesa into forest. Cistus looks pretty but, because it is resinous, is a fire hazard.

Cork is the primary product of the Portuguese dehesas (montados), while in Spain it is secondary to beef and ham. The 200 million bottles of champagne produced in France each year are still stoppered with Spanish or Portuguese cork. But dehesa cork has to compete with Moroccan cork in a market where plastic and metal caps seal cheap wine bottles and wine boxes are increasing.

The economic justification for farmers retaining their dehesas is equally dependent on the market for the acorn-flavoured ham from the dark Iberian animals. Because of African swine fever - a highly infectious virus - the jamon iberico cannot be exported to other parts of Europe where organic meat can attract a premium price. Both Spain and Portugal have eradication policies; if successful, access to a bigger market could help to secure the survival of the dehesas.

In 1986, the Extremaduran regional government introduced a law to prevent tree-cutting and to oblige farmers to manage their dehesas. Nevertheless, a better economic base would provide a more positive form of security. The Spanish Ornithological Society (SEO) is pressing for the establishment of Environmentally Sensitive Areas (ESAs) so that farmers can be paid to retain traditional management. 'The government is willing to help to fund oak planting,' says the society's Miguel Naveso. 'But the scheme is only for a maximum of 80,000 hectares over five years. We have asked for ESAs to be established but, so far, the government has refused, even though most of the money would come from Brussels.'

In the long term, the SEO may succeed. In the meantime, the most immediate - and pleasurable - help we can give to conserve a host of other wildlife in one of the most stunning landscapes in Europe is to drink plenty of rioja and champagne.

(Photographs omitted)