Long-term observations show that climate change is gradually affecting tree diversity in the Amazon and Andes: in some forests, the number of species is decreasing, while in others it is increasing.

New Study: How Tropical Forest Biodiversity Is Changing

A recent study published in the journal Nature Ecology and Evolution has revealed significant changes in the species composition of trees in the tropical forests of the Amazon and Andes over recent decades, against the backdrop of ongoing global environmental changes.

The research, led by Dr. Belen Fadrique from the University of Liverpool, is based on 40 years of detailed tree records collected by hundreds of botanists and ecologists at long-term forest plots. This has enabled one of the most comprehensive assessments of biodiversity changes in some of the planet’s richest ecosystems.

Hidden Dynamics: Regional Differences

Although overall tree species richness across South America has remained stable, this balance masks significant regional differences. In several large areas, a decline in species numbers was observed, while in others, there was an increase. These contrasting trends indicate that climate change is having uneven effects on tropical forests, leading to different outcomes depending on the region.

Climate Impact: Where Species Are Lost and Gained

The analysis showed that forests exposed to higher temperatures, drier conditions, and strong seasonal fluctuations tended to lose tree species more often. Meanwhile, ecosystems with more stable and natural conditions frequently gained new species. The greatest losses were recorded in the Central Andes, the Guiana Shield, and Central-Eastern Amazonia, where most long-term plots showed a decline in diversity. At the same time, the Northern Andes and Western Amazonia stood out as regions where the number of tree species increased in most plots.

While rising temperatures had a broad impact, the study found that rainfall levels and their seasonal variability play a key role in shaping these regional trends.

Northern Andes: A Potential Climate Refuge

One of the key findings was the identification of the Northern Andes as a possible “refuge” for tree species affected by climate change. As conditions worsen in other areas, this region could become a sanctuary for species displaced from surrounding forests.

Scope and Significance of the Study

The team analyzed data from across the tropical regions of South America—a region home to more than 20,000 tree species. The research covered ten countries and included 406 long-term floristic plots, which have been surveyed repeatedly since the 1970s and 1980s. These rare and consistent records made it possible, for the first time at this scale, to identify the key ecological factors driving changes in tree species composition.

How Plants Respond to Warming

Plants have limited ways to cope with climate change: they can shift their range or adapt to new local conditions. If a species cannot move or adapt, its population may decline, increasing the risk of extinction.

Dr. Fadrique noted: “Our work assessing species’ responses to climate change points to profound shifts in forest composition and species richness at multiple scales.”

The Need for a Regional Approach to Conservation

Professor Flavia Costa from the National Institute of Amazonian Research (INPA, Brazil) emphasized: “This study shows the uneven impact of climate change on tree diversity in different tropical forests, highlighting the need for specific monitoring and conservation strategies in each region.”

Professor Oliver Phillips from the University of Leeds, head of the pan-Amazonian RAINFOR network, added: “Our findings underscore the vital link between forest conservation, biodiversity protection, and combating climate change. It is especially important to protect the remaining forests at the interface of the Amazon and Andes—only by preserving these areas can we ensure a long-term home for species from the surrounding lowlands.”

Future Research Plans

The researchers plan to continue studying how climate change affects the diversity of tropical trees. Dr. Fadrique stated: “Future research will focus on the complex questions of species composition, including the taxonomic and functional traits of disappearing and emerging species, as well as whether this points to a large-scale process of homogenization in the Andes and Amazon regions.”

International Collaboration

This study is the result of collaboration among more than 160 scientists from 20 countries. Many universities and research partners from South America contributed, and the work was supported by major research networks, including RAINFOR, Red de Bosques Andinos, the Madidi Project, and the PPBio network.