VOLUME 18 NUMBER 2 (July to December 2025)

Exploring the potential of low-cost portable CO₂ meter in the assessment of soil CO₂ efflux in Philippine mangroves

Mangroves are critical carbon sinks that play a vital role in the global carbon cycle. However, studies examining soil CO₂ emissions in Philippine mangroves remain limited. This study assessed the soil CO₂ efflux of mangroves in Prieto Diaz, Sorsogon (northeastern Philippines) across different stand types (as natural, recolonized, and restored stands) and examined other ecological parameters influencing it. Using a handheld CO2 meter in a modified static closed chamber, we observed the highest mean CO₂ efflux in recolonized sites (19.00 ± 4.59 MgCO₂ ha^-1 yr^-1), followed by the restored (16.46 ± 4.90 MgCO₂ ha^-1 yr^-1) and natural sites (15.30 ± 3.10 MgCO₂ ha^-1 yr^-1). However, we found no significant differences across stand types. Additionally, we found that soil CO₂ efflux was positively correlated with canopy cover (r = 0.52) and negatively correlated with faunal burrow density (r ‒0.40) and width (r = ‒0.36). Compared to other studies, our mean CO₂ efflux values were in the lower range, probably due to the lower sensitivity of the handheld CO₂ meter (an acknowledged limitation of this study). Nonetheless, our findings highlight the potential of the low-cost handheld CO₂ meter for community-based monitoring of mangroves, particularly in assessing the contribution of managed mangroves in the reduction of CO₂ emission.