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The cork oak - use natural cork, protect the ecosystem
Sustainable consumption usually means choosing the lesser evil, i.e. using materials whose production harms nature as little as possible. For some products, however, demand protects unique biotopes with an immense biodiversity. These include natural cork, which comes from the bark of the Cork oak the Iberian Peninsula and North Africa.
A special bark
The cork oak is the only tree whose bark can be peeled off without the plant dying. Even more: regular peeling makes the oak resistant to fire, produces a thicker layer of cork and binds about 5 times as much CO2 as "normal" trees. In total, the cork oak forests of the Mediterranean convert 14 million tons of CO2 into cork every year.
Adaptation to the Mediterranean climate
The cork oak has adapted to the dry summer in the Mediterranean. It closes the stomata on the underside of the leaves so that it hardly loses water, but at the same time the tree does not dry out; their roots reach a depth of several meters and draw more than 70% of the water from there in summer.
Cork is an elastic fabric that firstly does not allow water to pass through and secondly it is highly insulating. They are dead cells with a substance called suberin. These also produce other trees, but only the cork oak can form from this bark. For this purpose, it forms new cork rings every year via mother cells.
It insulates heat well. What makes the bark attractive to humans probably helped the tree to survive in evolution and is an adaptation to the forest fires that are natural occurrences in the Mediterranean.
For example, only the seeds of the maritime pine and only the saplings of the holm oak survive forest fires, and the entire branches of the cork oak that the cork protects. It is therefore no coincidence that cork oaks are the dominant species in the forests named after them.
A biodiversity hotspot
An adapted fauna and flora can be found in the cork oak forests of Andalusia and Portugal, which loses its habitat without the traditional use of the bark. In fact, the Spanish cork oak forests have been largely cleared to give way to "lucrative" eucalyptus plantations that are poisonous for the endemic flora and fauna.
The cork oak forests of the Sierra Morena north of Seville, for example, are home to the largest population of the Spanish lynx, also known as the lard, because its close spots are reminiscent of a leopard. The Iberian relative of the Eurasian lynx weighs only a third of the local cousin, concentrates as prey on rabbits and is much more dependent on connected forests than the Eurasian lynx.
It is the rarest cat species in the world, in 2017 the population was between 215 and 265 specimens, most of which are concentrated in two protected areas in Andalusia: the Coto de Donana National Park and the Sierra de Andújar in the province of Jaén.
A cultural landscape
The province of Jaén is by no means an “original” wilderness, but a cultural landscape that has been used for centuries. The locals traditionally live from the cork oaks. A tree provides up to 200 kilograms of bark in its lifetime. To harvest them, the users do not kill the oak, but peel the bark off the living tree, which does little damage to it. The acorns are used for traditional pig fattening.
The forest pastures called Dehesa in Spain have been created since ancient times because the shepherds drove their pigs, cattle, goats and sheep into the previously dense forest. Cattle and sheep ate the grass, pigs the acorns. The jungle became a park-like landscape that depends directly on the cattle drive.
It is a sensitive system. In modern times, farmers also fed the animals with cattle feed, and the intensive animal fattening ensured that the mass of the animals ate the renewable trees. That is why many existing cork oak forests are outdated. Many other farmers gave up on pasture masts entirely, which led to the park-like cork oak trees becoming bushy. The result is forest fires that hit the Spanish peninsula almost every year.
Water storage and soil fertilizer
Cork plantations have an important role in the water balance and have an enormous influence on how the water penetrates and drains on the surface, the trees retain water. They prevent erosion and save rain. The treetops collect more water than the plants on the ground, and the water flows down to the ground at the trunk, making the soil there more receptive.
Cork oaks provide the soil with nutrient-rich material, which is of crucial importance for the fertility of the earth in the Mediterranean.
As in the past in this country, the pig farmers run forest pastures. The black or red-brown animals live, mostly fenced in, under the cork oaks, which at the same time give them the necessary shade in the blazing heat of the southern Spanish summer and provide them with plenty of acorns as food.
The Cerdo Iberico is proven to have been bred by Roman legionaries. It is smaller and faster than the modern high-performance breeds and delivers the Jamón Ibérico terminado en montanera. Gourmets love this ham because the acorns of the stone and cork oaks provide a taste that is reminiscent of walnut. At the Rebeco Jamón iberico, the pigs are fed pigs with acorns, but in the end they are also supplied with grain and conventional cattle feed.
The pigs live close to nature in a way that almost corresponds to that of wild boar. In fact, the black to red-brown color is probably due to the fact that wild boars repeatedly covered the free-grazing domestic pigs.
The forest pasture ensures that there is little undergrowth on the bottom of the forest, creating an open area that in turn provides a habitat for various reptiles, birds and mammals.
Vulture and eagle
The cork oak forests of the mountains north of Seville not only offer a habitat for the Spanish lynx, but also for a variety of greetings that are unique in Europe. Above all, these are the extremely rare Spanish imperial eagles and black vultures.
Golden eagles and griffon vultures breed in the higher parts of the mountains and prefer rocks to nest. Imperial eagles and vultures are dependent on cork oaks as brood trees. The vulture, very rare in Europe, has its main distribution on the continent in the Spanish cork oak forests. In the Sierra Morena, conservationists cleared the ecologically harmful eucalyptus trees and planted cork oaks in their place to create a habitat for the black vultures. The nowhere common hawk eagles live mainly on forested mountain slopes and have an ideal habitat in the Sierra Morena, as do the little eagles and snake eagles.
Up to 50,000 cranes overwinter in the cork oak forests of Spain, and more than half of all Mediterranean plants are found only here. Other fauna in the cork oak forests include wild cat, gorse, wild boar, red deer, bee-eater, blue louse, common raven, hawk and honey buzzard, peregrine and tree falcon, black and white stork, jay cuckoo, eagle owl and gliding hair, wryneck, small woodpecker, red-necked goats , Stonechat, Orpheuss mockers, Pale mockers, Orpheus warbler, Spectacled, Provence and Whitebearth warbler, mountain warbler, red-headed shrike, garden redstart, fence hammer and Ortolan, red grouse.
As in this country in the orchards, the cork oaks are a paradise for birds who need open areas with old trees. These include hoopoes such as little owl and scops owl, who raise their young in the caves of old cork oaks. This includes the blue rag, which disappeared from Germany when these open landscapes with trees disappeared, like the snake eagle, which breeds on low trees and searches for its food, lizards and snakes, on sunny hills.
An extraordinary fabric
Cork oaks are resistant to fire and heat, cold and injuries. They owe this to their bark and their cork layer. The cork protects the trees from drying out in the hot summers, it keeps infections out and even stands against forest fires. In house walls, cork keeps heat and cold out, and as a shoe sole it cushions the steps. In wine bottles, it not only serves as a closure, but also ensures that the wine can breathe.
Cork floats on the water, is perfect for insulating homes, keeps out heat as well as cold and sound, and lasts almost forever.
Around a quarter of the harvest now serves as a bottle stopper. The rest is ground and glued with binders. This creates pressed cork, cork flooring, shoe soles, pin boards or insulating cork.
Unprocessed pieces of cork bark are sought after by animal keepers, especially for rodents and terrariums, for many reasons: First, the bark peeled from the tree offers a round or semicircular shape that lizards, frogs, snakes, hamsters, rats or mice use as shelters.
Second, cork does not mold, a benefit for anyone who thinks rainforest dwellers like tree frogs who need exactly the high humidity that molds love.
Thirdly, the elastic and resilient cork offers excellent protection against the teeth of rodents and the claws of lizards, and at the same time a resilient surface that protects the feet of the animals.
Bloom, decline and upswing
Plastic corks or screw caps often replace corks made from oak bark. The demand for "real" corks is the best way to permanently protect the cork oak forest habitat and is therefore one of the most valuable biotopes in Europe.
Mass production of cork began in the 18th century. It reached its peak around 1900 because cooling ships contained cork as insulation. But in the 1960s the cork industry collapsed - the cause was the new plastics at the time, which were not only cheap, but were also considered modern.
The decline in prices due to a lack of demand led to a wrong reaction from producers: they harvested more cork to get the same income as before. This over-harvest damaged the trees.
In addition, the cities in southern Spain and Portugal expanded more and more - where old cork forests once stood, today concrete castles stretch. Other stocks of cork oak gave way to monocultures for tomatoes or flowers. The biggest cork oak killer became the eucalyptus plantations.
Eukayptus mainly uses the wood and paper industry. The trees grow quickly. Ecologically they are a disaster. They drain the water from other trees and their oil causes them to go up in flames in a forest fire.
Today, however, the cork industry has recovered a little: cork granulate sells well, so that the “waste” of bottle corks also finds a market and is popular as a health-friendly binder. Cork recycling slows down the risk of overusing the oak stocks.
In Germany today 70% of all wine bottles are sealed with aluminum, a material that is harmful to the environment and releases almost 25 times as much CO2 as cork made from cork bark.
Cork is a natural product. Winning it does not harm the ecosystem, but ensures that it is preserved. If cork bark is carefully broken down, it is a sustainable product in the best sense of the word. (Dr. Utz Anhalt)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Dr. phil. Utz Anhalt, Barbara Schindewolf-Lensch
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