The Amazon rainforest ranks among Earth’s biggest carbon stores and serves as the planet’s primary source of biogenic volatile organic compounds. These natural carbon gases, emitted by plants, help shield trees from stress such as oxidative damage and insect attacks. In the air, the compounds interact quickly with other gases, affecting particle and cloud formation that shapes regional climate and rainfall.
Scientists at the Max Planck Institute for Biogeochemistry and Brazil’s National Institute of Amazonian Research examined how rising temperatures could alter these emissions. At the Amazon Tall Tower Observatory, researchers recorded VOC releases alongside plant traits tied to photosynthesis and heat resistance. The study appears in Communications Earth & Environment.
The team compared two tree groups with different leaf strategies. Evergreen species keep foliage year-round and dominate the region, while brevideciduous trees shed most leaves for up to a month in the dry season. Higher leaf temperatures led to markedly increased VOC output and a shift toward more reactive, carbon-heavy compounds such as monoterpenes and sesquiterpenes, especially in brevideciduous trees.
These reactive gases can strongly influence atmospheric chemistry. The change also means forests release more carbon as temperatures climb. Lead author Michelle Robin noted that the groups employ distinct heat responses: isoprene-emitting brevideciduous trees show higher baseline photosynthesis, whereas non-emitting evergreens maintain greater water-vapor transpiration and thermal stability.
Earlier work indicated that seasonal leaf loss can protect against drought and herbivores. Continued warming could push more trees toward brevideciduous habits, further raising VOC releases. Models that included these leaf-turnover patterns produced more accurate isoprene estimates than standard methods.
Climate forecasts predict hotter conditions and more frequent heat waves in the Amazon. The findings imply shifts in how trees allocate carbon, with potential effects on atmospheric reactivity, aerosols, clouds, and carbon cycles at regional and larger scales.
