Assessment of carbon stock of Bustos Watershed, Bulacan, Philippines using Integrated Valuation of Ecosystem Services and Trade-offs (InVEST)

Abstract

Land use and land cover changes are pivotal factors contributing to global environmental concerns, particularly in forest cover reduction, accretion of greenhouse gas emissions, intensification of climate change, and the overall depletion of natural resources. These challenges are evident in Bustos Watershed in Bulacan, Philippines, where ongoing land conversion underscores the necessity of evaluating carbon storage in the area. Carbon stock (C-stock) assessment is essential in determining the trade-offs associated with transitioning between different land uses. Such assessment, in turn, serves as a foundational criterion for decision-making amid highly competing land uses. Hence, this study assessed the forest C-stock of Bustos Watershed using data from Landsat 5 (2009–2010) and Landsat 8 (2020–2021) satellites. The carbon storage and sequestration model of Integrated Valuation of Ecosystem Services and Trade-offs (InVEST), the generated land cover maps, the available carbon (C) values from different literature, and the C-stock of the watershed area were estimated. The findings reveal that forests remain the dominant cover type within Bustos Watershed in 2010 and 2021. However, a noteworthy decline of 21.6% in forest cover is evident during the intervening period, which may be related to conversions to alternative land cover types, including agriculture (9.38%), grassland or shrubland (10.68%), and built-up areas (0.51%). Consequently, the total C-stock experienced a discernible decrease of 12.58% by 2021, highlighting the substantial impact of land use changes on carbon sequestration within the Bustos Watershed.