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Water yield is an important service since it plays a significant role in supporting ecosystems, human livelihood, and economic activities. It is a valuable indicator for understanding the significance of water resources in specific geographic regions. This paper focuses on the valuation of water supply as an ecosystem service in the subwatersheds of the Upper Pampanga River Basin (UPRB) by applying the InVEST model in both scenarios of business-as-usual (BAU) and development. The model incorporates economic valuation techniques, i.e. net present value (NPV), thereby enabling the assessment of the monetary value associated with water supply. The results of this study show that there is a slightly decreasing trend in the annual water yield values in both scenarios. In terms of land area, the largest area under the projected BAU and development scenario (2020-2027) is grassland and forest, respectively. The results provided insights into how land use changes and climate variability affect water yield, with the BAU scenario yielding a total annual water volume of 2.3 billion m³ compared to 2.1 billion m³ in the development scenario. Furthermore, the NPV is estimated at PHP 24.6 billion for the BAU scenario and PHP 22.4 billion for the development scenario. These findings are pivotal for decision-making frameworks, hence underscoring the imperative of sustainable land use practices and water resource management in the UPRB. The study underscores the necessity of conducting a comprehensive assessment of ecosystem services to facilitate a balanced trade-off analysis, particularly at the subwatershed or watershed levels. This approach ensures that all factors influencing water yield and ecosystem health are considered, hence providing valuable insights for informed decision-making and effective resource management in the region. [ABSTRACT FROM AUTHOR]

Protected areas (PAs) are becoming extremely important ecotourism destinations. These areas are at risk from uninformed and unregulated visitors who can cause pollution (air, noise, water, etc.) and alteration of the natural ecosystem processes. An effective ecotourism planning and management approach should consider and define an optimum threshold level for the use of ecotourism attractions while maintaining a sound biophysical and social environment. Although carrying capacity is important in regulating visitor influx, the application and practice of this concept are not currently being observed in Malabayabas Forest, Pinagbanderahan Peak, and Pinagbanderahan Trail, which are the main ecotourism destinations of the Quezon Protected Landscape (QPL) in Atimonan, Quezon Province, the Philippines. This paper focuses on the carrying capacity estimates of these attractions considering site-specific physical, biological/ecological, and social factors. Data on visitation characteristics were collected through a questionnaire-based survey administered to 82 respondents in the months of August and December 2015. The real carrying capacity (RCC) estimates were found to be 289, 25, and 951 visitors for Malabayabas Forest, Pinagbanderahan Peak, and Pinagbanderahan Trail, respectively. The results demonstrated that actual visitations in these attractions are still below the carrying capacity estimates. However, there is still a risk for congestion and overcrowding, particularly during high visitation periods; without these thresholds, the influx of visitors poses serious pressure on the natural resources as well as ecological balance, which may lead to subsequent degradation of the PA. The study results can be used as an input in crafting a responsive visitor management program for QPL. Likewise, it can serve as a model in the determination of carrying capacity for other ecotourism sites in the country. [ABSTRACT FROM AUTHOR]

Carbon sequestration is one of the most important forest ecosystem functions that has been recognized globally but the dynamics are highly influenced by the alteration of forest cover. Given the different development thrusts in the Laguna province, the estimation and monitoring of carbon storage become an important activity. This study aims to estimate the carbon stock in the Silang-Santa Rosa and Pagsanjan-Lumban watersheds and explore the possible changes as an effect of land use changes. Sentinel-2 and Landsat 5 satellite images covering different time periods were classified to generate the land use maps. The process of carbon stock estimation was implemented using the carbon storage and sequestration model of Integrated Valuation and Ecosystem Services and Tradeoffs (InVEST) software. Carbon pool data for the land uses were obtained from different studies and estimates. Classified images covering different time periods showed that the largest land uses among the different land uses in the selected watersheds are built-up and agriculture. Much of the carbon stock was attributed to the high carbon pool values of the forest class. The reduction of forest areas in the watersheds resulted in a decrease in the total carbon stock. The generated land use scenario showing the continued built-up and agriculture expansion decreased the carbon stock further. The estimation of carbon stock based on different land use change scenarios will help in the evaluation and planning of future land use. [ABSTRACT FROM AUTHOR]

Reforestation activities were employed in several locations of the Philippines due to deforestation. However, many of these efforts fail because of various reasons, one of which is the poor selection of species. This study aimed to improve chances of success of reforestation in one of the critical watersheds in the Philippines, the Pantabangan-Carranglan Watershed (PCW), through a Geographic Information System (GIS)-based species-site suitability assessment of selected native tree species. Thematic maps of soil properties, climate, topography, and biotic conditions were generated for the watershed. The silvical requirements of the selected native species were also established through a literature review. Thereafter, a species-site suitability analysis was done using a GIS platform with the importance of each site feature given different weights through an Analytic Hierarchy Process (AHP), an approach that hasn't been done in previous GIS-based species-site suitability assessment. Results showed that of the three species analyzed, "akle" [Albizia acle (Blanco) Merr.] was found to be the most suitable in the site, with 53% of the watershed falling under high suitability class, while "dita" [Alstonia scholaris (L) R. Br.] and "almaciga" [Agathis philippinensis (Warb.)] were both found to be suitable to the identified reforestation areas of PCW, signifying that they are able to potentially survive within the existing environmental conditions of the site. The generated spatial distribution maps of species-site suitability can serve as guides to the managers of the watershed in future reforestation activities. [ABSTRACT FROM AUTHOR]