Diurnal and seasonal patterns of soil CO₂ efflux from the Pichavaram mangroves, India

The diurnal and seasonal variation of soil carbon dioxide (CO₂) flux was measured in the Pichavaram mangrove forest, the Southeast coast of India from February 2016 to October 2016 using an automated soil CO₂ flux chamber system. Maximum soil CO₂ efflux reached at 14:00 h and minimum at 00:00 h. The surface soil CO₂ concentration ranged from 375 to 532 ppm with the mean 405 ± 18 ppm. The daily soil CO₂ flux varied from near zero to about 7 μmol m⁻² s⁻¹ with a mean value of 2.4 ± 1.3 μmol m⁻² s⁻¹. The highest seasonal CO₂ efflux from soil was during the summer and premonsoon seasons, whereas low flux values were recorded during the monsoon season. Soil CO₂ efflux values were highly correlated with soil temperature. Tidal inundation during monsoon season, extreme drought condition in summer, and unusual precipitation are the major factors controlling the soil CO₂ flux.