Manguao catchment is situated between 10°43’30” to 10°47’30” North Latitude and 119°31’0” to 119°35’30” East Longitude, within the jurisdiction of Barangays Poblacion, Bantulan, Calawag and Bato in the Municipality of Taytay in northern Palawan covers an estimated area of 4,705 hectares (ha). The general topography is gently sloping to undulating to rolling. Eighty-one (81%) percent of the whole catchment is between 0-100 m elevation while the remaining 19 percent consist of 100-300 m elevation. Five hundred ninety-one (591) hectares of the catchment area form part of Malampaya Sound Protected Landscape and Seascape (MSPLS) which is part of the nine Protected Areas in Palawan (GIS, 2021). Lake Manguao, which can be found inside Manguao catchment, has been declared as part of the Local Conservation Area based on Memorandum Order No. 196-2014 by the Department of Environment and Natural Resources (DENR) – Biodiversity Management Bureau (BMB) in 2018. The study of Gonzales and Matillano (2014) of the Western Philippines University, commissioned by Palawan Council for Sustainable Development, indicated that the lake has been recognized as Key Biodiversity Area in Palawan due to its global importance for biodiversity conservation. The avifauna survey conducted from August 2005 to May 2006 by Matillano (2007) in Lake Manguao provides an adequate information towards avian species composition of the lake, which was subsequently used as a benchmark for declaring the area for protection. The study recorded a total of 126 species, wherein 24 were migratory species, 26 were resident, 14 were restricted range Palawan-endemics, 7 were Philippine endemics, and 5 had both resident and migratory population. The initiative of the Provincial Government of Palawan to undertake reforestation project in 2018 spearheaded by the Office of the Provincial Agriculturist aims to restore the affected ecosystem due to slash and burn agriculture type of system (PNA, 2018). Therefore, mapping urban sprawl and predicting future landscape transformation is critically important to determine the extent of landscape alteration and its adverse impact in an area considered as ecological sensitive region.
Table 2. Quantitative Distribution of Land cover in Manguao Catchment in 2008, 2016, 2020 in hectares
Using GIS, the estimated area of the six land cover classes used in this study were calculated. Table 2 shows the estimated extent of the land cover classes from period of 2008 to 2020. Quantitatively, massive expansion of agriculture has been recorded; it increased by three-folds or almost 10% as reflected from Figure 2. Other land cover classes that are consistently expanding from 2008 to 2020 are built-up and kaingin. With these expansions, forest area has been compromised with almost 12% decrease in area from the same period. According to Dessie & Bredemeier (2013), forest degradation is more associated in shortage of agricultural lands in the lower irrigated area due to the population growth. Comparably, Manguao Catchment is manifesting this phenomenon. As the catchment has been recognized as part of key biodiversity area in Palawan due to its global importance for biodiversity conservation, it is important to highlight the effects of forest degradation on ecosystem integrity by reducing the availability of goods and services; such as carbon or water regulation and biodiversity, due to species extinction, loss of natural habitats and changes in species distribution (Eguiguren, Fischer, & Günter, 2019).