Amazon Forest Faces Silent Biodiversity Loss as Climate Pressures Mount

Deep in the world’s largest rainforest, scientists are finding that the kaleidoscope of tree life that has long defined the Amazon may be quietly fading in some regions, as rising temperatures and shifting rainfall patterns take their toll.

An international team of ecologists has documented troubling declines in tree species richness — the number of different tree species — across parts of the Amazon and adjacent Andean forests over the last four decades. The findings, published this month in the journal Nature Ecology & Evolution, January 2026 suggest that climate change, combined with other environmental pressures, is reshaping the composition of these tropical forests in complex and uneven ways.

In some areas of the vast Amazon basin, researchers observed that hotter, drier conditions have coincided with a measurable drop in the variety of tree species. This regional decline, scientists say, points to mounting ecological stress that could have far-reaching consequences for biodiversity, carbon storage and ecosystem resilience.

“Our work is showing that changes to climate are quietly redistributing tree diversity,” Belén Fadrique, the lead author of the study and a research fellow at the University of Liverpool explain in the report. “Across the Amazon and Andean forests, places that are becoming hotter and more seasonal are losing species richness, while other parts of the region show stability or even increases.”

The research team compiled data from 406 permanent forest plots scattered across the Andes and Amazon, representing repeated measurements of tree species composition dating back to the 1970s and 1980s. Those plots, maintained by hundreds of field scientists over decades, offer one of the most comprehensive records of forest change in Earth’s most biodiverse tropical regions.

By analyzing these long-term records, scientists were able to detect subtle but significant trends over time. While species richness remained roughly stable when viewed across the entire study area, that overall picture masked stark differences at smaller scales.

In the central sections of the Amazon and certain Andean foothills, where climate models and local weather data indicate rising temperatures and increasing dry periods, researchers recorded declines in the number of tree species in many plots. These losses were particularly evident in zones experiencing intensified heat stress and less frequent rainfall, conditions linked to longer dry seasons and more extreme weather patterns.

“These forests have evolved over millions of years under relatively stable climatic conditions,” Fadrique said. “Now they are being pushed into new territory. Some species may be unable to cope, leading to a reduction in local diversity.”

The patterns observed mirror broader concerns about how tropical ecosystems are responding to global warming. Tropical rainforests like the Amazon host an estimated tens of thousands of tree species and play a central role in regulating the planet’s climate by absorbing carbon dioxide from the atmosphere. A reduction in species richness could weaken these forests’ ability to function as effective carbon sinks and support the myriad forms of life that depend on them.

Flavia Costa, a professor at the Instituto Nacional de Pesquisas da Amazônia (INPA) in Brazil and one of the study’s co-authors, emphasized that the observed changes are not uniform across the landscape. “Not all forests are responding in the same way,” Costa said. “Where ecosystems remain relatively intact and climatic changes are less extreme, some areas are maintaining or even gaining species. But the losses in central Amazonia and parts of the Andes are a serious warning sign.”

Scientists are still working to unpack the full implications of these shifts, including which tree species are most vulnerable and how changes in diversity might affect wildlife, Indigenous communities and regional climates. Some species may migrate to cooler, wetter areas if they are able, while others could face local extinction if conditions become inhospitable.

Ecologists also warn that tree species losses may have cascading effects on the broader ecosystem. Many animal species, from insects to birds and mammals, rely on specific tree species for food and habitat. As those trees disappear, the intricate networks of ecological relationships that have evolved over millennia may begin to unravel.

The study’s authors stress the need for continued monitoring and conservation efforts to better understand and mitigate these changes. Protecting large swaths of intact forest and maintaining connectivity between habitats could give tree species greater opportunity to adjust to changing conditions.

Oliver Phillips, professor of tropical ecology at the University of Leeds and co-leader of the Amazon Forest Inventory Network (RAINFOR), also explained the study highlights a critical intersection between conservation and climate policy. “These forests are not just repositories of biodiversity. They are living, dynamic systems that are now being forced into new states by human-driven climate change. If we want to preserve their complexity, we have to act on both fronts — reduce greenhouse gas emissions and protect the forests themselves.”

The research, titled “Tree diversity is changing across tropical Andean and Amazonian forests in response to global change”, was published online in Nature Ecology & Evolution and draws on contributions from more than 160 scientists across 20 countries.

As the planet continues to heat, the Amazon’s towering giants — and the countless species they harbor — may be facing a transformation unlike any seen in human history, researchers warn. (Wage Erlangga)