In this study, the authors measured CO2_C fluxes using eddy covariance over a hydrological year on pastures within a cattle farm in the Brazilian Pantanal that experienced seasonal flooding. Their measurements show that seasonally flooded pastures were large emitters of CO2_C, contributing 337 g CO2_C m−2 year−1 to the atmosphere.
During flooding, when the soils were anaerobic, and soil O2 was close to zero, the flooded pasture was a net sink of -18 g CO2_C m−2, while during the aerobic phase (soil O2 > 15%) the pasture was a significant CO2 source to the atmosphere (301 g CO2_C m−2). Transitions to and from anaerobic conditions corresponded to 54 g CO2_C m−2.
The results indicate that the seasonally flooded cattle pastures in the Brazilian Pantanal may be an important regional source of CO2_C for the atmosphere. Better management, and use of drought resistant grasses, may be a way to improve soil C stocks and limit emissions, especially as global climate change is anticipated to increase heating and drying for the Pantanal biome.
- CO2 flux was measured with eddy covariance in a seasonally flooded pasture.
- The pasture was a large C emitter, emitting 337 g CO2_C m−2 y−1 to the atmosphere.
- The pasture was a C sink when soil was anaerobic but a source when soil was aerobic.
- Low productive pastures in the Pantanal may be important sources of atmospheric CO2.
- Management and altered hydrology of Pantanal pastures can reduce net CO2 uptake.