Portugal’s cork oak forests are part of an ancient Mediterranean ecosystem that has more than 13,000 native plant species. Portugal has the largest cork oak forest area in the world. The cork oak is its national tree and has been protected by law since the 13th century. The cork oak forest is important to migrating birds, reptiles, amphibians, large and small animals and food production (think of acorns and the famous black pig and the highly valued (and priced) “Pata Negra” cured ham). The cork oak forests form one of the richest ecosystems in terms of biodiversity, being recognized by environmental NGOs as one of the 35 world hotspots. They cork oak forests are listed alongside Amazonia, the Andes and Borneo.
The cork oak’s tree roots are extensive, holding onto steep hillsides preventing erosion, protecting watersheds and preventing desertification. From an environmental perspective the cork oak regenerates its bark after harvest and because of this it stands to absorbs between 3 to 5 times more CO2 than a tree from which no bark is taken. The cork oak forests impede forest fires because they do not burn as well as other timber, like pine. And unlike timber, only a small part of each cork oak tree is harvested. They go on living after bark stripping!
A 2009 PriceWaterhouseCoopers report found that CO2 emissions for the lifecycle of aluminum screw caps were 24 times that of natural cork stoppers, and plastic “corks” were ten times that of natural cork stoppers. Cork is a living product and everything can be used. Cork’s saw dust is used in factory furnaces and offcuts are made into other products. The corks themselves can be recycled by grinding them down for other products such as sandal soles. Even if they are not recycled, cork is a natural and highly biodegradable product. It can break down without causing environmental degradation.
What about Cork Taint? The chief cause of cork taint is the presence of the chemical compound trichloroanisole (TCA). In many cases this will have been transferred from the cork to the wine, but also it can be transferred through the cork rather than from it. TCA is a compound which does not occur naturally, but is created when some fungi are treated with chlorinated phenolic compounds (bleaches, antimicrobials and preservatives). Modern day research and practices have served to markedly reduce this problem in the cork industry. Aluminum screwtops are generally considered to offer a TCA free seal. However they also reduce the oxygen transfer rate between the bottle and the atmosphere to almost nil, which can lead to a reduction in the quality of the wine. Because of their impermeability, screw caps and plastic corks are thought to be prone to a different aroma taint, that of sulphidisation. The reduced oxygen supply can concentrate sulphurous smells arising from wines with sulphite based preservatives. Aluminum screwtops with their plastic liners are also very difficult to recycle.
The World Wildlife Federation notes on their website: Cork forests – home to endangered species such as the Iberian lynx and Iberian imperial eagle – have been protected and valued due to the centuries old demand for cork in the wine industry. But the increasingly popular use of alternative stoppers threatens this environmentally and economically sustainable industry and leaves cork forests unprotected.