For over two decades, WWF has been telling wine producers to put a cork in it, extolling the virtues of cork stoppers over cheaper alternatives. The reasons for this global campaign include habitat preservation, sustainable development, and carbon sinks.

For nearly three centuries, winemakers have sealed glass bottles with cork. In the 1980s, though, winemakers around the world switched to cheaper plastic and aluminum stoppers and screw caps. Over twenty years ago World Wildlife Fund (WWF) launched the Put a Cork in It campaign because a drop in demand for cork would have detrimental long-term effects far beyond the bottle.

Despite rising temperatures and the devastating fires of 2022, resulting in nearly 260,000 acres burned across Portugal, the country is leading the way with recent biodiversity, conservation, and sustainability wins.

The Natural Biodiversity of Portugal’s Cork Oak Forests

Portugal is the world’s leading producer and exporter of cork. The country is home to the largest area of cork oak forest in the world, covering over 1.8 million acres. That represents over one-third of the world’s total cork woodlands. Portugal exports around 65% of the world’s cork.

Portugal cork oak tree forest

Cork oaks have grown for millennia on the Iberian peninsula. Cork oak fossil remnants over 10 million years old have been found in Portugal. Native and perfectly adapted to the soil, water, and geography of Portugal, cork forests are not monocultures, but a rich mix of trees and grasslands known in Portugese as the montado. This diverse ecosystem is home to a wide variety of endemic plants and animals, creating a remarkably sustainable coexistence between nature and material production.

When it appeared alternative wine closures may reduce the need for cork, large-scale industrial farming and property developers began transforming Portugal’s ancient cork woodlands, prompting mass wildlife displacement and calls to action and campaigns from WWF.

The cork oak (Quercus Suber L) is a medium-sized evergreen oak that has a thick corky bark. It thrives across southern and central Portugal in the montano, a traditional agroforestry system where low density trees are combined with other low-impact, sustainable agricultural or ranching activities. Cork oaks are the most typical trees characterizing the Montado.

The montado is not exclusively agricultural, forestry or pastoral; it is a permaculture landscape developed over millennia for stability in harsh conditions. The montado can vary from thick forest to more open grassland and scrub vegetation areas interspersed by trees. Cork oak forests grow from sea level up to 500 m in the humid and warm climates of the Mediterranean basin, particularly in the southern regions of the Iberian Peninsula influenced by the Atlantic Ocean. Cork forests rank among the most biodiverse areas in the Mediterranean and Europe. In cork oak woodlands, plant diversity levels can reach 135 species per square meter.

In Portugal alone, 37 different species of mammals can be found in cork oak forests, including the critically endangered Iberian lynx, the most threatened feline species in the world. Rabbits, weasels, deer, and mongoose. 42 bird species, including kestrels, little owls, black storks, and the endangered Iberian eagle can be found in the treetops of the montado.

spanish imperial eagle iberian eagle perched on a cork oak tree

Iberian eagle (also known as the Spanish Imperial eagle) perched on a cork oak tree

The balanced ecosystem of the montado has many valuable environmental and cultural functions, including soil and water conservation, protecting habitat for a rich biodiversity of wildlife and fauna, and providing for the livelihoods of local residents who harvest the bark of the cork tree while acting as responsible stewards of the forest.

A Sustainable Agroforestry and Habitat Restoration Success Story

Cork trees are so important to the communities in which they are grown in Portugal (where it is also the national tree) that they have protected by Portuguese law since 1209. Each one is identified and regulated individually.

Cork is a renewable product made from the bark of the cork oak tree, which regenerates after being harvested. The cork oak is the only tree whose bark regenerates, acquiring a smoother texture following each harvest. It takes 25 years after planting for a cork oak to start to produce cork. It is harvested by hand about every 9 years.

Over the course of its lifetime, which can last over 200 years, a cork oak tree may be stripped around 17 times. Each time the bark grows back, it removes CO2 from the atmosphere, holding it within its cells where it remains even after the bark is made into cork stoppers or flooring or any other product. The montado also acts as a carbon sink. Each stopper holds within it an estimated 112gm of CO2.

“The harvesting of the bark of the cork oak offers one of the finest examples of traditional, sustainable land use.
—World Wildlife Fund

cork oak production harvesting

Since the Put a Cork in it campaign, the more recent Green Heart of Cork project, spearheaded by WWF, has been touted by the EU as a nature restoration success story. The campaign has aimed to conserve the world’s largest area of cork oak forests – in the lower valley of the Tejo (or Tagus) and Sado river basins – by compensating landowners who contribute toward good farming and forest practices.

Cork is a vital source of regional rural employment, as the cork is harvested between May and August by specialized professionals. the skills needed to harvest cork bark have been handed down through generations, and the workers are among the highest paid agricultural workers in the world. In this way the cork industry supports not only the environment, but entire multi-generational families and communities – indeed, an entire culture.

Harvesting and producing cork requires no trees to be cut down. No deforestation or habitat destruction at all. In fact, Iberian lynx are a conservation success story.

Habitat Preservation and Wildlife 

In 2002, there were fewer than 100 Iberian lynx left in the wild; none remained in Portugal. Their main threats were habitat loss and a declining food base. Rabbits are the preferred prey of the Iberian lynx. Various epidemics and habitat loss caused the rabbit population to decline. Habitat loss from infrastructure creation led to barriers between lynx populations. The expanding road network has also caused an increase in car collisions. Finally, illegal hunting and poaching still threaten the Iberian lynx despite being protected since the 1970s.


WWF has been working toward the conservation of the Iberian lynx for decades and manages a captive breeding program as well as lobbying for the protection of the lynx’s habitat, the montado. The Spanish and Portuguese governments have made great efforts to maintain the species population.

Iberian lynx

Iberian lynx

The Lynx Program was launched in 2004 by a group of conservation organizations with the aim of ensuring the conservation and long-term management of the Iberian lynx’s habitat, such as the cork oak forests. The ambitious aim of the program was to show how local economic activities, such as the harvesting of cork, could be compatible with the conservation of endangered species and their habitat.

In 2023, there are 15 core habitats spread across the Iberian Peninsula, with more than 80% of the wild cats located throughout central and southern Spain and the rest in Portugal, where 261 lynxes have been counted. The number of endangered Iberian lynx in the wild in Spain and Portugal reached 1,668 in 2022. This is by all accounts a conservation success story.

Portugal Leads the Way in Wine Industry Sustainability

In addition to the valuable habitat cork forests provide, cork trees help protect against soil erosion through wind and lowers the water erosion and run off rate. The tree tops create a microclimate which prolongs the growing season. In creating a natural cork stopper, processing is minimal, without additives, glues, and less use of energy than used to produce other stoppers. Each stopper is 100% recyclable and can be used in a variety of applications, from artistic projects to construction materials. For these reasons, cork is truly carbon negative and a rare agricultural resource that is an important asset in fighting climate change and desertification.

cork oak forest wildlife habitat herd of deer

There is recognition across Portugal that the wine and cork industries have potential to pave a path toward more sustainable practices. The wine sector, due to its territorial, economic, social and environmental importance, can lead the way in adapting to climate change and promoting sustainability.

Portugal’s wine industry has taken a proactive role in promoting sustainability through the Porto Protocol, established in 2018. Born out of a pact between wineries to mitigate climate change and enhance their practices, the Porto Protocol has rapidly gained momentum and now boasts over 250 members, spread across five continents, 20 countries, and the entire wine value chain.

This collaborative initiative encourages peer-to-peer learning and the adoption of eco-friendly methodologies, fostering a culture of continuous improvement within the industry. By sharing knowledge and best practices, the Porto Protocol empowers wineries to act collectively and contribute to global sustainability efforts.

Notably, Portugal’s pioneering efforts in wine sustainability have garnered international recognition and admiration. The country’s success stories, from the conservation of cork oak forests to the revival of the Iberian lynx population, have inspired nations worldwide to adopt similar practices.

One of the regions where Portugal’s commitment to sustainability shines is the Douro River Valley, a UNESCO World Heritage Site and the oldest demarcated wine region in the world. For centuries, vineyards have clung to steep terraced slopes here, employing techniques to preserve and protect this unique landscape. The Douro Valley’s wine producers have been at the forefront of implementing sustainable viticulture practices, reducing water usage, and promoting biodiversity conservation.

Alentejo winery vineyards

Alentejo winery vineyards

In Alentejo wineries have been adopting organic and biodynamic farming methods, minimizing chemical inputs, and prioritizing soil health. In partnership with local communities, conservation organizations, and government agencies, Alentejo’s wine producers are committed to ensuring the long-term preservation of the region’s natural resources and cultural heritage.

Portugal’s unwavering dedication to wine sustainability is not just an isolated pursuit; it permeates the country’s entire viticulture landscape. By preserving its over 1.8 million acres of cork oak forests, Portugal protects not only its natural heritage but also supports local economies and fosters a tradition of responsible stewardship. The success of Portugal’s cork industry is a testament to the effectiveness of sustainable practices and showcases the potential for environmental conservation through economic activity.

In conclusion, Portugal is a trailblazer in wine sustainability. With the Porto Protocol spearheading collaborative efforts and the Douro River Valley and Alentejo regions leading by example, Portugal’s commitment to ecological responsibility is evident across its viticulture landscape.

Experience Portugal’s Wine Culture for Yourself

If you’d like a glimpse into Portugal’s wine culture, Natural Habitat Adventures offers a remarkable trip from Porto up the Duoro River. This is further north than the cork forests, and designed for the active traveler who loves nature, authentic culture, and great food and wine.

Douro River Valley

Douro River Valley

Our Douro River paddling adventure begins in the historic center of Porto, and the majority of your time is spent in the UNESCO World Heritage Site the Alto Douro Wine Region, which is the world’s oldest demarcated wine region. You’ll stay in authentic quintas—the Vineyard Estates of the Douro Valley.