Climate Change Is Quietly Transforming the World’s Richest Forests

Climate change is quietly rearranging the Amazon and Andes—winners and losers are emerging, and the Northern Andes may hold the key to forest survival.

A new study published in Nature Ecology and Evolution finds that tree diversity across the tropical forests of the Andes and Amazon has shifted significantly in recent decades as a result of global environmental change.

Led by Dr. Belen Fadrique of the University of Liverpool, the research draws on four decades of tree records collected by hundreds of botanists and ecologists working in long-term forest plots. The dataset provides one of the most detailed views yet of how the world’s most biologically diverse forests are responding to a changing climate.

Stability at a Continental Scale Masks Local Losses

When researchers examined tree diversity across South America as a whole, they found that overall species richness has remained relatively stable. However, this broad pattern hides sharp differences between regions.

Large areas experienced declines in tree species, while other regions showed gains. These opposing trends reveal that climate change is not affecting tropical forests evenly.

Heat and Rainfall Drive Uneven Forest Change

Forests located in hotter, drier, and more seasonal environments were more likely to lose species over time. In contrast, forests with healthier ecosystems and naturally dynamic conditions often gained new species.

The strongest declines were observed in the Central Andes, the Guyana Shield, and Central Eastern Amazon forests, where most monitoring plots recorded a loss of tree species. Meanwhile, the Northern Andes and Western Amazon showed the opposite pattern, with most plots gaining species.

Rising temperatures had a widespread influence on forest diversity, but the study found that rainfall levels and seasonal rainfall patterns played a major role in shaping these regional outcomes.

Northern Andes May Serve as a Climate Refuge

One of the most striking findings is the identification of the Northern Andes as a potential “refuge” for tree species affected by climate change. As conditions become less suitable in surrounding lowland forests, this region could offer a safer habitat for displaced species.

The research covers an enormous area across the South American tropics, home to more than 20,000 tree species.

Scientists analyzed data from 406 long-term forest plots across ten countries. These plots have been measured repeatedly since the 1970s and 1980s, allowing researchers to track changes in tree species richness over time and pinpoint the environmental factors driving those changes.

How Plant Species Cope With Climate Change

Plant species have limited ways to respond to a warming climate. They can shift their geographic ranges as conditions change, or they can adjust to new environments where they already grow. When species are unable to move or adapt, their populations may decline, increasing the risk of extinction.

Researchers Emphasize Conservation Urgency

Dr. Fadrique, a Dorothy Hodgkin Royal Society and University of Liverpool Research Fellow in the Department of Geography & Planning, conducted the research while she was a Marie Curie Fellow at the University of Leeds.

She said, “Our work assessing species responses to climate change points to profound changes in forest composition, and species richness at multiple scales.”

Flavia Costa, Professor at INPA (Instituto Nacional de Pesquisas da Amazônia) in Brazil, added, “This study underscores the uneven impacts of climate change on tree diversity across different tropical forests, highlighting the need for specific monitoring and conservation efforts in each region.”

Professor Oliver Phillips of the University of Leeds, who leads the pan-Amazon RAINFOR network, stressed the added threat of deforestation. He said, “Our findings stress the vital links between preserving forests, protecting biodiversity, and fighting climate change. It is especially critical to protect remaining forests where the Amazon meets the Andes. Only if they stay standing can they offer a long-term home to species in adjacent lowlands.”

What Comes Next for Forest Research

The research team plans to continue studying how climate change is altering tropical forests. Future work will focus on identifying which species are being lost or gained and whether these changes signal a broader trend toward increasing similarity across forests in the Andes Amazon region.

Dr. Fadrique said, “Future studies will focus on complex compositional questions, including the taxonomic and functional identities of species being lost or recruited, and whether this points to a large-scale process of homogenisation within the Andes-Amazon region.”

Reference: “Tree diversity is changing across tropical Andean and Amazonian forests in response to global change” by B. Fadrique, F. Costa, F. Cuesta, G. Arellano, L. Cayuela, T. R. Baker, F. C. Draper, A. Esquivel-Muelbert, H. ter Steege, M. Bauters, J. Aguirre-Gutiérrez, Z. Aguirre-Mendoza, M. N. Alexiades, E. Alvarez-Davila, E. Arets, E. Ayala, C. G. A. Aymard, F. Baccaro, S. Báez, C. Baraloto, R. I. Barbosa, P. Barbosa Camargo, J. Barlow, P. E. Barni, J. Barroso, M. Benchimol, A. C. Bennett, E. Berenguer, L. Blanc, D. Bonal, F. Bongers, R. Brienen, F. Brown, M. BT Andrade, B. Burban, R. J. Burnham, J. L. Camargo, S. P. C. Carvalho, C. Castilho, J. Chave, F. Coelho de Souza, J. Comiskey, L. da Costa, R. B. de Lima, E. A. de Oliveira, R. L. C. de Oliveira, R. de Oliveira Perdiz, J. De Rutte, J. del Aguila-Pasquel, G. Derroire, A. Di Fiore, M. Disney, A. Duque, T. Emilio, W. Farfan-Rios, S. Fauset, P. M. Fearnside, K. J. Feeley, T. R. Feldpausch, J. Ferreira, L. Ferreira, G. R. Flores Llampazo, D. Galbraith, K. García-Cabrera, M. García Criado, E. Gloor, J. M. Grandez-Rios, B. Hérault, J. Homeier, E. N. Honorio Coronado, I. Huamantupa-Chuquimaco, W. Huaraca Huasco, Y. T. Huillca-Aedo, Á. Idárraga, O. Jadán-Maza, M. Kalamandeen, T. J. Killeen, S. G. W. Laurance, W. F. Laurance, A. Levesley, W. Lopez, M. J. Macía, W. E. Magnusson, Y. Malhi, A. G. Manzatto, B. S. Marimon, B. H. Marimon Junior, J. A. Martínez-Villa, M. B. Medeiros, K. Melgaço, L. Melo, T. Metzker, A. Monteagudo, P. S. Morandi, J. A. Myers, H. M. Nascimento, R. Nascimento, D. Neill, B. Nieto-Ariza, W. A. Palacios, S. Palacios-Ramos, N. C. Pallqui-Camacho, G. Pardo Molina, J. Peacock, M. A. Peña, R. T. Pennington, M. C. Peñuela, C. A. Peres, Á. J. Pérez, G. C. Pickavance, E. Pinto, J. Pipoly, N. Pitman, A. Prieto, H. Ramírez-Angulo, S. M. Reis, Z. Restrepo, C. Reynel, S. Ribeiro, G. Rivas-Torres, R. Rojas, A. Rudas, N. Salinas, R. P. Salomão, F. Santana, J. Schietti, G. Schwartz, J. Serrano, M. Silman, C. Silva, C. A. Silva, R. C. Silva, R. S. A. Silva, J. Silva-Espejo, M. Silveira, M. F. Simon, Y. C. Soto-Shareva, P. F. Souza, D. Storck-Tonon, J. Stropp, V. Swamy, J. S. Tello, J. Terborgh, R. Thomas, A. Torres-Lezama, J. D. Vale, L. Valenzuela Gamarra, G. van der Heijden, P. van der Hout, P. J. van der Meer, R. Vasquez Martinez, L. Vedovato, H. Verbeeck, I. Vieira, S. A. Vieira, E. Vilanova, B. Vinceti, V. A. Vos, R. Zagt, P. A. Zuidema and O. L. Phillips, 23 January 2026, Nature Ecology & Evolution.
DOI: 10.1038/s41559-025-02956-5

The study represents a major international effort involving more than 160 researchers from 20 countries. Many contributors were based at South American universities and research institutions. The work was supported by large collaborative networks, including RAINFOR, Red de Bosques Andinos, the Madidi Project, and the PPBio network.

Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.