Overview

• Published in Nature Plants, the analysis draws on 30 years of ground measurements from 188 intact plots monitored by nearly 100 RAINFOR researchers across the Amazon.
• Tree size increased across all classes, with the largest trees gaining fastest and increasingly dominating resources.
• Although only about 1% of individuals, the biggest trees account for roughly half of the forest’s carbon cycling and storage.
• Researchers attribute the trend to CO2 fertilization but caution that intensifying droughts, heat, fires and storms could slow growth and raise mortality in the coming decades.
• Findings apply to intact mature forest; fragmented areas have shifted from carbon sinks to sources, and demographics show fewer small-stem and understorey trees as large trees increase.