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.