In Chile, a Declining Forest Worries Scientists

At the age of 10, Alberto Alaniz joined a school field trip to Río Clarillo National Park, a forested reserve near Chile’s capital. He remembers the experience vividly: The sight was dense with trees and the air was comfortably cool. Recently, more than two decades later, Alaniz returned to Río Clarillo only to witness a distressing reality. 

“There wasn’t a forest anymore,” he recalled. “There was a scrub.”

Over the last 15 years, Chile has faced a devastating drought. Higher temperatures and lower rainfall have severely affected the country’s sclerophyllous forests—one of only five Mediterranean ecosystems in the world, best known for its hardy, evergreen vegetation.

In the last few years, tree canopies have also browned at unprecedented levels, losing their green color and ability to remove carbon dioxide from the atmosphere. Additionally, deforestation—driven by urban expansion and the introduction of non-native tree species—has fragmented the forests into multiple, smaller patches.

Such environmental shifts have had natural, economic and cultural consequences. Endemic species are now at risk of extinction. Pollination has decreased considerably, affecting the majority of local beekeepers. Meanwhile, rural communities feel increasingly anxious, dreading rising temperatures and more frequent wildfires.

The implications have been personal, too. “To see that the ecosystems you had in your childhood are no longer the same can be very impactful,” said Alaniz, now a postdoctoral fellow at the University of Santiago, Chile. A member of the university’s Laboratory of Biodiversity and the Environment since 2020, he studies the effects of anthropogenic climate change on ecosystems across the country.

A study published Feb. 10 in the journal Science of the Total Environment estimates the level of risk faced by all individual sclerophyll forest stands, in the central and coastal zones of Chile, often at altitudes from 4,500 to 7,200 feet. “This is the most detailed risk analysis for this type of forest that has been done,” said Alaniz, the paper’s corresponding author.

Together, these findings demonstrate that the forest is now less capable of supporting biodiversity, storing carbon and recovering from natural disasters, said Juan Ovalle, an assistant professor at the University of Chile’s Faculty of Forest Sciences and Nature Conservation. 

“Dr. Alaniz’s work is valuable and reaffirms a process of forest decline that has accelerated with the intense droughts that have occurred in the last 15 years in central Chile,” he said. 

Though not involved in the study, Ovalle has been vocal about the sclerophyllous forest crisis. “Some species have lost a significant portion of their habitat due to low rainfall, wildfires and land use changes,” he said. 

In 2024, a group of Chilean scientists, including Ovalle, published a letter calling upon the Chilean state to implement urgent conservation measures to protect an endangered palm species native to the sclerophyllous forest.

“It is necessary that state authorities think of alternative solutions,” Alaniz said. His team’s study presents a detailed risk map for each part of the country’s sclerophyllous forests, effectively providing a clear blueprint for action. “The government should take these layers of information and overlap them with different territorial policy instruments, such as land-use plans.” He argues that his article serves as “an explicit guide on where to act.” 

Based on the study’s findings, Alaniz suggests restricting land-use changes in high-risk forest units and allocating more funds for restoration. Ovalle, on the other hand, recommends elevating endangered endemic species to natural heritage status, affording them robust legal protections.

Without such measures in place, the future of the forests remains increasingly uncertain. “There has been subsequent growth, especially after the rains of 2024,” said Benito Rosende, a postgraduate student pursuing a Ph.D. in ecology at the Pontifical Catholic University of Chile. “We can now see that the forest is green again, but with the presence of dead trees and dry branches.”

Ovalle also notes that 2023 and 2024 have been relatively more humid years, but cautions that precipitation continues to be well below average pre-drought levels. “The sclerophyllous forest is very threatened,” he said. 

“It remains risky to talk about the concept of collapse because the system itself is very resilient,” Ovalle said. “We don’t know if the forest in general will adapt to these conditions of lower rainfall and water supply, growing less but persisting over time. Or if it will simply collapse, exceeding a threshold at which climate conditions in general will become unviable for such forms of life.”

For scientists like Alaniz, the possibility of losing this ecosystem is more than an imminent risk—it is a call to preserve a natural heritage that shapes the personal experience of many Chileans.

“The other sense that exists in me is uncertainty, the uncertainty of not knowing what may happen in the future and how we are going to advance in order to stop what is happening,” said Alaniz.

He thinks about his upbringing, how he would go on trekking trips with his friends in the forest. “That is when one realizes that it is necessary that kids also get to know this,” he said. “We got to experience it as children.”