Climate change could significantly disrupt emissions and uptake of greenhouse gases in the Amazon rainforest, with wide-reaching global consequences. Rising temperatures and increased flooding are affecting microbial activity in floodplain and upland forest soils, leading to contrasting changes in methane dynamics, warns new research from the University of São Paulo.
The study, recently published in the journal Environmental Microbiome, points to an alarming shift in methane uptake and emissions. Given the Amazon’s critical role in regulating global methane levels, these changes could contribute to worsening greenhouse gas concentrations worldwide.
Floodplains in the Amazon, which cover over 800,000 square kilometres during the rainy season, contribute up to 29 per cent of global wetland methane emissions. In these waterlogged areas, methane-producing microbes thrive as they break down organic matter. However, new findings indicate that upland forests, which typically act as methane sinks, are highly vulnerable to changes in temperature and humidity levels.
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Lead author Júlia Brandão Gontijo, currently a postdoctoral researcher at the University of California, Davis in the United States, and her colleagues subjected soil samples from both ecosystems to extreme conditions, temperatures of 27°C and 30°C and varying humidity levels, during a 30-day experiment. Their research demonstrated that while methane emissions in floodplains remained stable, the number of methane-producing microbes increased.
In contrast, methane uptake in upland forest soils plummeted by 70 per cent in dry, warm conditions, pointing to the greater sensitivity of upland soil microbes to temperature fluctuations. Higher temperatures reduced the overall number of bacteria and archaea in upland forests, while increasing the proportion of specialist microbes, the study also revealed, highlighting the fragility of these ecosystems in the face of climate change.
Source: downtoearth.org
