Home / Science / Drought Turns Rainforest Floor Into Gas Emitter
Drought Turns Rainforest Floor Into Gas Emitter
2 Sep
Summary
- Drying soil shifted from absorbing to releasing volatile organic compounds.
- Microbial activity changed carbon metabolism during drought.
- Rewetting rainforest caused a burst of carbonyl and sulfur compound emissions.
In a controlled drought experiment within Arizona's Biosphere 2, researchers discovered that drying rainforest soil can reverse its role in atmospheric gas exchange. Previously, the soil acted as a sink, absorbing several volatile organic compounds (VOCs). However, as soil moisture fell below approximately 19%, the soil began releasing these compounds into the atmosphere.
The Biosphere 2 Water, Atmosphere and Life Dynamics (B2-WALD) experiment monitored soil moisture and VOC exchange in the facility's enclosed tropical rainforest. Under normal conditions, the soil consumed VOCs like isoprene and alcohols. As the drought intensified, microbial activity declined, but a shift in their carbon metabolism occurred. Evidence suggests that during drought, soil microbes produced more volatile metabolites like acetate and acetone, leading to increased emissions.
Upon rewetting the rainforest after 65 days without rain, scientists observed a rapid release of carbonyl compounds, followed by sulfur-containing gases. This dynamic response indicates that drought and subsequent rewetting trigger complex chemical reactions. These findings suggest that increasing drought frequency due to climate change could alter the balance of VOCs between tropical forest floors and the atmosphere globally.
