Research Findings

Amazonian trees are getting larger on average, yet the continental carbon sink is weakening as species composition shifts faster than trees can adapt to rising temperatures. Across tropical Andean and Amazonian forests, tree diversity is changing at rates that outpace local adaptation, with montane forests showing the fastest compositional turnover.

Repeated burning in the southern Amazon causes stepwise simplification of forest structure and species composition, even in secondary vegetation recovering from earlier clearing. Canopy recovery after fire is strongly stage-dependent: younger regrowth is more vulnerable but recovers faster, while older secondary growth is more resilient but rebuilds more slowly.

Agricultural conversion eliminates 38% of soil organic carbon in addition to 100% of aboveground biomass, yet fire alone does not significantly reduce soil carbon. Across elevation gradients from lowland Amazonia to the Colombian Andes, climate and soil type together determine how much carbon accumulates and persists after disturbance.

In the South American Cerrado, 30 hyperdominant tree species account for a disproportionate share of biomass — and these same species show the greatest vulnerability to future climate change. Across tropical Andean and Amazonian forests, tree diversity is shifting in response to warming and land-use change, with distinct thresholds between montane and lowland systems.

GEDI satellite lidar detects consistent structural differences across Amazonian degradation gradients — from intact forest to burned and cleared plots — providing a scalable tool for tracking fire impacts and carbon stock changes. L-band SAR backscatter is primarily controlled by vegetation water content and structure rather than biomass alone in dry tropical ecosystems, informing how satellite-based carbon mapping should be calibrated.

Amazonian secondary forests show stage-dependent responses to fire: younger forests are more vulnerable but recover faster, while older secondary growth is structurally more resilient but rebuilds more slowly after disturbance. At the continental scale, tropical forests in the Americas are not shifting their composition fast enough to track the pace of climate change, raising fundamental questions about long-term carbon sink stability.