Assessment of blue carbon stock of mangrove vegetation in Infanta, Quezon, Philippines

Venice Jiezzelle Nesperos; Carlos Mico Villanueva; Josephine Garcia; Dixon Gevaña

Venice Jiezzelle C. Nesperos Graduate School, University of the Philippines Los Baños, College, Laguna 4031, Philippines
Carlos Mico M. Villanueva Department of Social Forestry and Forest Governance, College of Forestry and Natural Resources, University of the Philippines Los Baños, College, Laguna 4031, Philippines
Josephine E. Garcia Department of Social Forestry and Forest Governance, College of Forestry and Natural Resources, University of the Philippines Los Baños, College, Laguna 4031, Philippines
Dixon T. Gevaña Department of Social Forestry and Forest Governance, College of Forestry and Natural Resources, University of the Philippines Los Baños, College, Laguna 4031, Philippines

Keywords: coastal, cover change, climate change mitigation, rehabilitation, remote sensing

Abstract

Mangroves provide a natural solution for sequestering atmospheric carbon. Quantifying the potential carbon storage in mangrove ecosystems is crucial in harnessing mangrove’s function for climate change mitigation. The objective of this study is to assess the carbon stock of mangrove vegetation in Infanta, Quezon through remote sensing. To determine the spatiotemporal changes in mangrove area by vegetation density (bare, sparse, and dense) of different barangays, Normalized Difference Vegetation Index (NDVI) analysis was done using corrected satellite images through ArcGIS. The annual rate of change (%) of mangrove forests was computed. Accuracies of the NDVI images were calculated using semi-automatic classification plugin (SCP) of QGIS, which showed a high accuracy of the classification process. Secondary data on aboveground mangrove carbon stocks in San Juan, Batangas, and the computed mangrove area of Infanta were utilized in the computation of aboveground carbon stock and its corresponding CO2 equivalent. Over the 20-year study period, dense mangrove cover changed by –11.7%. Although there was an increase in dense mangroves of 2.6% over the 2000–2010 period mainly in Barangay Binonoan and Dinahican, the following decade (2010–2020) recorded a decrease of –14.2% implying that gradual mangrove deforestation or degradation persisted outweighing the reforestation efforts of various agencies in the study area. For the municipality as a whole, the estimated aboveground carbon stock for the years 2000, 2010, and 2020 were 304.3 Gg C, 310.7 Gg C, and 286.6 Gg C, respectively with corresponding translated equivalent values of 1,115 Gg CO2, 1,139.4 Gg CO2, and 1,050.8 Gg CO2. Mangroves of Infanta are worth at least USD 4.5 million at USD 4.3 ton–1 CO2 (prevailing market price as of 2020). As a result, mangrove forests in the research area should be continuously conserved to ensure sustained carbon sequestration and other equally important ecosystem services.