Amazon trees getting bigger, but why?
Tom Goreau
Tree size increases in all classes increases biomass carbon storage. The question is whether this is due to a CO2 fertilization effect or nitrogen pollution as suggested, or alternatively from increased weathering of rocks in the Andes causing increased supply of re-mineralized elements? If so there should be clear West-East biomass decline, which is indeed what the data shows, and which was well known since Spruce and Bates!
- Article
- Open access
- Published: 25 September 2025
Increasing tree size across Amazonia
- Adriane Esquivel-Muelbert,
- Rebecca Banbury Morgan,
- Roel Brienen,
- Emanuel Gloor,
- Simon L. Lewis,
- Kyle G. Dexter,
- Everton Almeida,
- Edmar Almeida de Oliveira,
- Esteban Álvarez-Dávila,
- Atila Alves de Oliveira,
- Ana Andrade,
- Simone Aparecida Vieira,
- Luiz Aragão,
- Alejandro Araujo-Murakami,
- Eric Arets,
- Luzmila Arroyo,
- Gerardo Aymard-Corredor,
- Olaf Banki,
- Plinio Barbosa de Camargo,
- Jorcely Barroso,
- Lilian Blanc,
- Foster Brown,
- José Luís Camargo,
- Wendeson Castro,
- …
- Oliver L. Phillips
Show authors
Nature Plants volume 11, pages2016–2025 (2025)
Abstract
Climate change and increasing availability of resources such as carbon dioxide are modifying forest functioning worldwide, but the effects of these changes on forest structure are unclear. As additional resources become available, for example, through CO2 fertilization or nitrogen deposition, large trees, with greater access to light, may be expected to gain further advantages. Conversely, smaller light-suppressed trees might benefit more if their light compensation point changes, while bigger trees may be the most negatively impacted by increasing heat and drought. We assessed recent changes in the structure of Earth’s largest tropical forest by analysing 30 years of Amazonian tree records across 188 mature forest plots. We find that, at a stand level, trees have become larger over time, with mean tree basal area increasing by 3.3% per decade (95% CI 2.4; 4.1). Larger trees have increased in both number and size, yet we observed similar rates of relative size gain in large and small trees. This evidence is consistent with a resource-driven boost for larger trees but also a reduction in suppression among smaller trees. These results, especially the persistence and consistency of tree size increases across Amazonian forest plots, communities and regions, indicate that any negative impacts of climate change on forests and large trees here have so far been mitigated by the positive effects of increased resources.
Foster Brown, one of the authors of this important paper, brought me to Amazonia in the early 1980s to measure soil GHG fluxes, and he never left, too busy measuring trees!
Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance
Chief Scientist, Biorock Technology Inc., Blue Regeneration SL
Technical Advisor, Blue Guardians Programme, SIDS DOCK
37 Pleasant Street, Cambridge, MA 02139
gor...@globalcoral.org
www.globalcoral.org
Phone: (1) 857-523-0807 (leave message)
Books:
Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase
Innovative Methods of Marine Ecosystem Restoration
On the Nature of Things: The Scientific Photography of Fritz Goro
Geotherapy: Regenerating ecosystem services to reverse climate change
No one can change the past, everybody can change the future
It’s much later than we think, especially if we don’t think
Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away
“When you run to the rocks, the rocks will be melting, when you run to the sea, the sea will be boiling”, Peter Tosh, Jamaica’s greatest song writer
“The Earth is not dying, she is being killed” U. Utah Phillips
“It is the responsibility of intellectuals to speak the truth and expose lies” Noam Chomsky