Spatial distribution of carbon dioxide (CO2) and nitrous oxide (N2O) concentrations across three mangrove zones in Ngurah Rai Grand Forest Park, Bali

Abstract

Beside their role as carbon sinker, mangrove soil can also emit greenhouse gases (GHG) through microbial metabolism. However, their emission was scarce in every mangrove zone. We measured the CO2 and N2O concentrations in Ngurah Rai Grand Forest Park, Bali, which experienced anthropogenic pressure. Rhizophora mucronata and Sonneratia alba dominated the mangrove vegetation in this area and have a characteristic zonation across the intertidal (landwards, middle, and seaward zone). Gas samples were taken above a height of 25 cm from mangrove soil during the wet season of 2020 at the three mangrove zones within three sites. Gas concentrations ranged from 303.09 - 330.57 ppm for CO2 and 0.51 - 0.53 ppm for N2O. CO2 and N2O concentrations were similar across mangrove zones, with a decreasing trend from the land toward the sea. A high density of mangrove trees was negatively associated with N2O; meanwhile, no soil and porewater parameters were significantly correlated with the gas concentrations. The result revealed that N2O concentration had exceeded the average value of the earth's atmospheric N2O concentration. This information is essential for complementing previous research variations on GHG emissions and helps support the inventory of GHG emissions from the forestry sector.