Standing under an enormous olive tree, José Pedro Oliveira gently caresses its gnarled trunk. “It is more than one thousand years. Maybe older than Christ,” he says.
Located near Serpa, in the gently rolling hills of Alentejo in southeastern Portugal, his 30-hectare olive grove is part of a mosaic of oak and fruit trees, pastures and agricultural land that has been passed down through generations.
From his family, Oliveira inherited his surname – which means “olive tree” in Portuguese – and the traditional landscape of montado, an agrosilvopastoral system that combines production and nature conservation.
“Many of these trees are thousands of years old, but they are still bearing fruit. It’s a living museum,” he says with pride. Every year, visitors come to marvel at the monumental trees and to study the grove’s 17 different local olive varieties.
Super-intensive olive plantations have taken over
Oliveira has preserved a diverse landscape that is becoming increasingly rare in Alentejo, as super-intensive monoculture olive plantations expand, replacing traditional orchards.
“It’s a staggering contrast. The only thing they have in common is that it’s the same species,” he says. Unlike his rain-fed olive grove with trees that have deep roots and a long lifespan, irrigated plantations can have up to 2,500 trees per hectare that are planted in uniform rows and last only a few decades.
These monoculture plantations use highly productive dwarf varieties adapted to mechanisation, achieving very high yields. However, they rely on irrigation, heavy machinery and agrochemicals, which lead to soil erosion and biodiversity loss.
The artificial lake feeding Portugal’s olive oil empire
Across Alentejo, the uniform hedgerows of olives stretch as far as the eye can see. The area’s irrigated plantations have expanded rapidly in the last two decades with the supply of water from the Alqueva reservoir, the largest artificial lake in Western Europe.
Built with public funds, the dam was designed to bring economic growth to one of the continent’s poorest and driest regions. But the irrigation has mostly benefited large corporate groups profiting from super-intensive olive plantations.
According to EDIA, the public company managing the Alqueva reservoir, more than 80 per cent of its water is used to irrigate intensive olive and almond plantations.
In 2024, it provided water to 74,059 hectares of olive groves, mostly super-intensive hedgerows. A few large companies like Elaia, De Prado and Aggraria – some of the world’s biggest olive oil producers – control the majority of the region’s irrigated land.
The construction of the Alqueva dam on the Guadiana River, first proposed by dictator António de Oliveira Salazar in the 50s, flooded 25,000 hectares of land, destroying ecosystems and submerging the village of Luz as well as dozens of archaeological sites.
More than one million trees were felled. A few old trees were transplanted before the flooding, and now adorn gardens and squares across Alentejo, standing as the last remnants of a vanished landscape.
Susana Sassetti, director of Olivum, an association representing olive producers with about 50,000 hectares of olive plantations, says that it was thanks to the Alqueva dam that Portugal became one of the world’s top exporters of olive oil.
Since the dam became operational in 2002, olive oil exports have increased 12-fold in volume and 18-fold in value, reaching about €900 million annually, she says.
The intensification of olive oil production has been driven by the EU’s Common Agricultural Policy (CAP) incentives and a global rise in olive oil demand. From 2007 to 2020, Portugal’s olive sector received over €1 billion in agricultural subsidies.
EDIA’s president, José Pedro Salema, says the dam has an important strategic role in ensuring the region’s water supply, and has created jobs and attracted investment.
However, the highly mechanised intensive plantations rely mostly on seasonal and poorly paid migrant labour.
The dam has not stopped rural depopulation. Between 2011 and 2021, Alentejo lost over 52,000 residents, the largest population decline in Portugal.
The environmental impact of intensive olive plantations
While Alqueva’s irrigation system and intensive olive plantations have been very profitable for investors in the short term, there are growing concerns about the environmental costs.
Scientists and environmentalists have warned that intensive olive farming in southern Portugal is transforming a once diverse landscape into monotonous rows of intensive plantations, damaging ecosystems and contaminating water and soil with agrochemicals.
For Teresa Pinto Correia, a professor at the University of Évora who specialises in rural landscapes, public investments in the Alqueva dam have mostly benefited a small group of big companies and foreign investors. This has led to land concentration and an unequal distribution of water at artificially low prices.
“The price of the water should account for the infrastructure, which includes not only the costs of building the dam but also the irrigation channels, water transportation, and the electricity needed to pump the water over long distances and to higher elevations, which is very expensive.” But this is not reflected in the price paid by users, she explains.
The dam represents the largest public investment made in agriculture in Portugal’s modern history, at a cost of €2.5 billion. EDIA plans to expand irrigation to cover an additional 470 square kilometres, a project that will also be financed with public funds.
“A lot of the companies [using Alqueva’s water] are investment funds focused on profit and completely detached from the territory. They are not thinking about passing on a sustainable future to the next generations” says Pinto Correia. She worries that these profits are being made at the expense of Alentejo’s natural resources, with little oversight or regulations.
ZERO, a leading environmental organisation in Portugal, has condemned the unchecked spread of monoculture plantations in Alentejo.
Pedro Horta, ZERO’s policy officer, has documented many environmental violations and infractions, including the destruction of vital water networks, damage to protected areas and priority habitats, as well as harmful agricultural practices that are causing soil erosion and degradation.
“Given the scale of the transformation of the landscape, we can call this an ecocide,” says Horta, pointing out that super-intensive plantations have led to significant biodiversity loss and environmental destruction.
A report published by EDIA found that intensive hedgerow plantations support only half the number of species found in traditional olive groves. Another study, by a team of researchers from different Portuguese universities, shows how the expansion of super-intensive agricultural systems is drastically reducing diversity and shrinking bird communities in Mediterranean olive orchards.
Climate change is exacerbating water stress
For many, the current trajectory is unsustainable in a region increasingly affected by drought and extreme weather events.
A study by the consulting firm Agrogés predicts that climate change will increase water demand for irrigated olive groves by 5 per cent to 21 per cent, while average annual inflows to the Alqueva reservoir are expected to decrease by 5 per cent to 10 per cent by 2050.
“We won’t have enough water,” says Pinto Correia. She fears that the simplification of ecosystems in homogeneous landscapes will make the region even more vulnerable to climate change.
Resting in the shade of an ancient olive tree that has endured centuries of drought, storms and natural disasters, José Pedro Oliveira is confident that unlike irrigated plantations, his rain-fed olive grove will continue to bear fruit for generations to come.
This project was supported by Climate Arena.
