The Pulse of the Tropics – canopy tree responses to climate and CO2

Summary

Tropical forests are at the heart of our planet’s carbon cycle, helping to slow climate change. Yet we still don’t fully understand how tropical trees respond to rising CO₂ and shifting climates. In this thesis, I explored how tropical canopy trees react to these changes. I found that higher CO₂ makes photosynthesis more efficient, but tree growth depends much more on year-to-year fluctuations in weather. In general, tropical trees grow less when the air is dry and more when rainfall is abundant—and reactions are especially strong in regions that are already dry. These patterns are shaped not only by photosynthesis but also by how trees balance growth and storing energy. In short, CO₂ changes how trees function, but climate drives how much they grow. As the tropics get hotter and drier, tropical forest growth—and their ability to store carbon—may decline.