In the sun-drenched countryside of Alentejo, southern Portugal, an extraordinary olive tree has stood for thousands of years. Located on the Herdade do Peso wine estate, near Vidigueira, this ancient tree is believed to be more than 3,700 years old, making it the oldest known olive tree in Portugal. Its remarkable age offers a rare glimpse into the country’s distant past, long before the Roman occupation of the Iberian Peninsula.
And it is not alone. The estate is home to nearly 80 other centuries-old olive trees, forming an exceptional collection of living natural heritage. Together, their estimated ages represent more than 7,000 years of history. Some of these trees were already growing when ancient civilisations flourished around the Mediterranean. Their twisted trunks and spreading branches have survived generations of agricultural change, making them remarkable witnesses to the history of this rural landscape.
A scientific method reveals the tree’s remarkable age
Determining the age of an olive tree is considerably more complicated than counting its growth rings. Ancient olive trees often develop hollow trunks, making conventional tree-ring dating unreliable or impossible.
Researchers at the University of Trás-os-Montes and Alto Douro (UTAD) developed a patented method to estimate the age of these exceptional specimens. The technique combines measurements of trunk diameter, height and circumference with mathematical modelling. According to the researchers, the approach has been validated through radiocarbon testing and can achieve a margin of error of approximately 2%.
Using this method, scientists have estimated that the oldest olive tree at Herdade do Peso has been growing for more than 3,700 years.
The research is the result of more than a decade of work by UTAD specialists, in collaboration with experts from Oliveiras Milenares, an organisation specialising in ancient olive trees. Their studies have helped establish the estimated ages of several remarkable specimens, including those at Herdade do Peso.
Some of this research was made possible by infrastructure projects, notably the construction of the Alqueva dam. These works brought researchers into contact with ancient olive trees that had previously been difficult to access, providing valuable opportunities to study their structure and longevity.
An unexpected haven for biodiversity
The Herdade do Peso estate covers approximately 465 hectares and is known primarily for its wine production. Yet its ancient olive trees are only one part of a much larger natural landscape, where vineyards, olive groves and native Mediterranean vegetation exist alongside one another.
Around 160 hectares are occupied by cultivated areas and natural habitats, including olive trees, neatly planted vines and vegetation characteristic of Alentejo. Among the species recorded are purple garlic, Cleonia, mastic trees, yellow bellflowers, roselha-grande and the azinheira, or holm oak.
This diversity reflects the relationship between agriculture and the surrounding environment. Estate owner Sogrape has made biodiversity conservation part of its sustainability programme, Seed the Future, which aims to protect natural resources and encourage responsible land management.
For Mafalda Guedes, Sogrape’s Director of Communications and Sustainability, preserving this landscape represents both a responsibility and a source of pride.
She emphasises the importance of protecting biodiversity, respecting the environments in which the company operates and safeguarding the estate’s natural heritage so that future generations can continue to benefit from it.
A living heritage rooted in history
Historical records provide another fascinating insight into the estate’s olive-growing past. A property sale document dating from 1791, associated with Desembargador Estêvão José Palha, already recorded the presence of 57 olive trees at Herdade do Peso.
Some of those trees may still be standing today. Their survival reflects not only the extraordinary biological resilience of olive trees but also the long agricultural history of this part of Portugal.
Olive trees possess an exceptional ability to regenerate. As they age, their original central wood may decay, leaving behind the hollow, irregular trunks characteristic of particularly old specimens. Yet living tissues around the outer parts of the trunk can continue growing, allowing the tree to survive and produce new shoots.
This capacity helps explain how some olive trees can remain alive for thousands of years, even after much of their original trunk has disappeared.
Their continued survival is not guaranteed, however. The condition of the soil, available water, agricultural practices and protection from physical damage all influence their long-term prospects. With appropriate care, these remarkable trees may continue growing for many centuries to come.
A natural treasure worth protecting
Portugal’s oldest known olive tree is far more than a botanical curiosity. It is a living monument connecting the country’s distant past with its natural heritage today. Protecting such trees means preserving a unique record of the relationship between people, agriculture and the Mediterranean environment over thousands of years.
Their extraordinary longevity should not obscure their vulnerability. Climate change, prolonged drought, agricultural pressure and expanding development all pose challenges to the landscapes in which ancient trees survive.
The 3,700-year-old olive tree of Vidigueira offers a powerful reminder of what can be lost when natural heritage is overlooked. Its survival demonstrates the remarkable adaptability of olive trees, but also the importance of maintaining the conditions that have allowed them to endure.
These ancient giants are much more than sources of olives and olive oil. They provide habitats for wildlife, contribute to local biodiversity and form part of the cultural identity of Alentejo.
Above all, they are living witnesses to thousands of years of Portuguese history, and a natural inheritance that deserves to be protected for generations to come.
