Flora & Fauna - Cork

The cork oak, quercus suber

Andalucia's cork industry

If you find yourself travelling in western Andalucía - anywhere from, say, Gaucin to Ubrique, Ronda to Vejer, almost as far as Algeciras - between June 15 and August 15 any summer (roughly) -you might catch a glimpse of the most enigmatic (legal) agricultural industry in Andalucía; the cork oak crop. Law forbids the cork oak collectors, usually employees of the cork factories at Cortes de la Frontera and elsewhere, from taking cork off the trees outside this brief period, as it might damage the health of the trees. The men spend two years at college studying their subject before they are so much as allowed near a tree with one of the array of special cork knives. Outside the two-month harvesting period, the men all have different jobs in the processing factories for the rest of the year.

People driving or hiking in this region will often find themselves passing fenced-in piles of wood; kindling, perhaps. Most are unaware that they are looking at hundreds of thousands, maybe even millions, of euros lying there on the ground. The Iberian cork industry - as well as bottle-stoppers, it's also used in diverse processes from car construction to aeroplane insulation - is worth an estimated two billion dollars. Following the disastrous forest fires in Portugal in 2003, Spain has become the world's biggest single producer of cork.

Some history

Originally, Andalucia's woodlands consisted mainly of mulberry trees, which nurtured silk worms for the production of the region's famed silks. This process is known as sericulture, and involved the silk worms being boiled alive to yield up their precious cargo. The gradual transition from mulberry to cork oak is still something of a mystery; some believe it was deliberate afforestation, planting, others that in some Darwinian battle, the mulberry lost its territory to the stronger cork oak.

The cork oak, quercus suber - quercus the Latin for oak, suber the Latin for cork - is a native of both northern and southern shores of the Mediterranean. Its age is unknown, but the quercus suber or its ancestors have been around for at least 147 million years, when an evolutionary Selection Event - probably a drastic change in climate - caused the decline of single-seed gymnosperm trees and the appearance of angiosperm - multi-seeded - plants and trees. More suited to propagation and seed distribution, the angiosperms, among them the earliest quercus species, spread around the Mediterranean, forming part of the maquis, or scrub, that would cover the Mediterranean basin for millions of years. Early man would have used quercus suber, among others of the quercus family (and there are dozens of varieties) for fire wood, implements, weapons and, when the hunter-gatherers began to settle in or around the thirteen century BCE, for building.

Archaeologists have found evidence of tribes actively working with quercus suber in northern Africa before 6,000 BCE. Similar evidence has been found in Andalucía and other parts of southern Spain dating back 4,000 years BCE or more. It would take thousands of years more before the special sealant qualities of cork would be used to seal containers of liquid. This property is due solely to the presence of one particular substance, suberin, like suber taken from the Latin for cork. Suberin is a fatty substance found in the cells of cork which, in the denser forms of cork stops the passage of air, or liquid, through the cork.

Cork was probably first used as a sealant on containers by the Greeks and Phoenicians, to seal wines and other liquids in amphorae, the fat-bellied, wide-mouthed pottery containers that are probably distant ancestors of the Spanish tinaja. It would take the invention of the glass bottle, a fairly recent innovation in historical terms, for cork to finally meet glass. Apocryphal legend claims that a French monk, the aptly-named Fr. Perignon, discovered the sealant qualities of cork on a slender glass bottle neck, some time in the seventeenth century. As news of its efficacy spread, so a new industry appeared. Previously, cork had been one of a number of wild tree and bush growths which farmers used for implements, firewood and construction. They had also actively begun to manage it, often using fire, to clear land for crops and livestock, and to put a distance between the maquis where wild animals lived and the human settlements appearing throughout the regions where quercus suber flourished.

Perfectly suited to nurturing quercus suber, which needs soil rich in silica, and a range of temperatures, from just below zero in winters to the low forties in high summer, and with a variable Mediterranean littoral climate at certain altitudes, Portugal and, to only a lesser extent, Spain, came to dominant the world cork market, in part because of both countries' expeditionary adventures around the Caribbean, the Atlantic Africa, and, for Spain, parts of the Americas stretching from Baja California down to Peru.

Don't try this at home

After their two years' training, the men join the gangs who roam the oak forests - Andalucia's Bosque del Alcornocales in the Parque Natural de Alcornocales is Spain's biggest single plantation - and each has a specific role in the (usually five-man) gang, from chief cutter to lowly carrier. The cutters' experience tells them how far to cut up the tree to avoid harming it. They travel around the forest in a nine-year cycle, allowing the trees they cut time to regenerate the cork (which is, in fact, a type of parasite on the bark of the tree beneath). Their burros, mules, roam free in the forest for the rest of the year, never straying too far from a free meal, but for the two month harvest they trek back and forth between harvest site and cork factory. So expert is their knowledge of the routes that, once loaded, a tap on the back will send them off unaccompanied to the factory. The town of Cortes de la Frontera actually holds burro-loading contests at its annual summer feria, with a prize for the most ingenious loading of a burro.

What we see lying curled on the ground is still many stages away from fitting into the neck of a bottle. At the factory the cork is boiled in a vast, deep (maybe 15 feet) pool of water, which renders it malleable for flattening and then processing by machine.

The cork then goes through several levels of compression, depending on its destination. It emerges as very thin sheets of varying sizes, perhaps thinner than a child's little finger. It is then checked for quality - the oak trade has five levels, from excellent to poor - and the oak is assigned to a particular use; insulation, say.

Most interestingly, however, is how it does reach the bottles we uncork. Bottle corks are stamped out by machines, at different widths for wine, champagne and cognac (Spanish cork is treasured by the French brandy producers). When they pile up in the dumpers beneath the pressing machines, they look like big wooden pennies.

These are graded by quality, and then carefully fed into further compressing machines. Cork makers reckon that it would be a waste of good cork to use it throughout a wine or champagne cork, so lower quality cork is placed in the middle, highest quality at either end, where the cork meets both wine and outside air. These layers are then compressed so tightly we do not even notice that a cork we pull is not one single unit but a compression of up to eight layers crushed together. The finished corks are then dispatched to bottling plants across Europe and beyond.

There have, of course, been murmurings about the rise of the plastic cork. Its proponents say that it prevents a bottle being 'corked', spoiled, by air penetrating the old-fashioned cork. Its detractors argue that, beyond the aesthetics of levering a wad of white plastic out of your favourite wine, it doesn't allow the alcohol to breathe naturally. (French brandies breathe so profusely that the distilleries are wreathed in fumes which promote fungi on the roofs and keep nearby cattle happily sozzled year-round.) Yet with even the British supermarket buyer seemingly moving upmarket in their choice of corked drinks, and the Spanish and French keeping their noses in the air over plastic corks, it seems the Iberian peninsula can hold on to its two billion euro cork industry yet.