Improving soil carbon estimates of Philippine mangroves using localized organic matter to organic carbon equations

Severino G. Salmo; Sean Paul B. Manalo; Precious B. Jacob; Maria Elisa B. Gerona-Daga; Camila Frances P. Naputo; Mareah Wayne A. Maramag; Mohammad Basyuni; Frida Sidik; Richard A. MacKenzie

doi:10.1186/s13021-024-00276-y

Treesearch

Improving soil carbon estimates of Philippine mangroves using localized organic matter to organic carbon equations

Formally Refereed

Authors:

Severino G. Salmo, Sean Paul B. Manalo, Precious B. Jacob, Maria Elisa B. Gerona-Daga, Camila Frances P. Naputo, Mareah Wayne A. Maramag, Mohammad Basyuni, Frida Sidik, Richard A. MacKenzie

Year:

2024

Type:

Scientific Journal

Station:

Pacific Southwest Research Station

DOI:

https://doi.org/10.1186/s13021-024-00276-y

Source:

Carbon Balance and Management. 19(1): 1089.

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Abstract

Southeast Asian (SEA) mangroves are globally recognized as blue carbon hotspots. Methodologies that measure mangrove soil carbon stock (SCS) are either accurate but costly (i.e., elemental analyzers), or economical but less accurate (i.e., loss-on-ignition [LOI]). Most SEA countries estimate SCS by measuring soil organic matter (OM) through the LOI method then converting it into organic carbon (OC) using a conventional conversion equation (%C_org = 0.415 * % LOI + 2.89, R² = 0.59, n = 78) developed from Palau mangroves. The local site conditions in Palau does not reflect the wide range of environmental settings and disturbances in the Philippines. Consequently, the conventional conversion equation possibly compounds the inaccuracies of converting OM to OC causing over- or under-estimated SCS. Here, we generated a localized OM-OC conversion equation and tested its accuracy in computing SCS against the conventional equation. The localized equation was generated by plotting % OC (from elemental analyzer) against the % OM (from LOI). The study was conducted in different mangrove stands (natural, restored, and mangrove-recolonized fishponds) in Oriental Mindoro and Sorsogon, Philippines from the West and North Philippine Sea biogeographic regions, respectively. The OM:OC ratios were also statistically tested based on (a) stand types, (b) among natural stands, and (c) across different ages of the restored and recolonized stands. Increasing the accuracy of OM-OC conversion equations will improve SCS estimates that will yield reasonable C emission reduction targets for the country’s commitments on Nationally Determined Contributions (NDC) under the Paris Agreement.

Keywords

Philippine mangroves, Carbon stock estimation, Soil organic carbon, Organic matter to organic carbon allometry, Loss-on-ignition, Conservation, Restoration

Citation

Salmo, Severino G.; Manalo, Sean Paul B.; Jacob, Precious B.; Gerona-Daga, Maria Elisa B.; Naputo, Camila Frances P.; Maramag, Mareah Wayne A.; Basyuni, Mohammad; Sidik, Frida; MacKenzie, Richard. 2024. Improving soil carbon estimates of Philippine mangroves using localized organic matter to organic carbon equations. Carbon Balance and Management. 19(1): 1089. https://doi.org/10.1186/s13021-024-00276-y.