Warming Effect from Soil Greenhouse Gas Emission of Each Mangrove Zone during the Dry Season in Ngurah Rai Forest Park, Bali, Indonesia

Abstract

In addition to functioning as a carbon sink, mangrove soil also releases greenhouse gases (GHGs) through microbial metabolism. GHG flux fluctuates according to the ecological parameters of mangroves and climate variability. We quantified GHG fluxes from the soil using a closed-chamber technique and assessed soil and porewater conditions in three primary mangrove zones (each zone was dominated by one of the mangrove types) at Ngurah Rai Forest Park, Bali, Indonesia, categorized by genera: Bruguiera, Rhizophora, and Sonneratia. We found that the CO2 flux ranged from 322.5 to 3,494.5 µg/m2/h, CH4 flux ranged from -24.7 to 60.9 µg/m2/h, and N2O flux ranged from -1.2 to 2.3 µg/m2/h. None of the GHG fluxes varied significantly between mangrove zones. Overall, the highest CO2 fluxes were observed in the Bruguiera zones, while the highest CH4 and N2O fluxes were found in the Sonneratia and Rhizophora zones, respectively. A significant relationship between GHG fluxes and soil properties, including soil organic carbon (SOC), total Kjeldahl nitrogen (TKN), water content, bulk density, and soil type. The average warming effect on GHG fluxes ranged from 0.9 and 1.8 MgCO2/ha/year, accounting for only 1.1% to 2.2% of the annual plant carbon sequestration rate of 75.9 to 81.6 MgCO2/ha/year. These findings suggest that the variability of GHG fluxes is not significantly influenced by mangrove type; instead, soil conditions play a crucial role. Calculations of the net carbon stock may overlook the relatively low warming effect of GHG fluxes in this area.

Keywords

• closed-chamber technique
• co2
• ch4
• n2o
• mangrove zones
• ghg flux variations