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Master's Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14578/4

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Discipline: search.filters.discipline.Science TeachingSDG: search.filters.sdg.SDG 6 - Clean water and sanitation

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    Mangrove community structure, aboveground biomass, and carbon stock assessment in the coastal area of Santa Cruz, Davao del Sur, Philippines
    Sante, Gle Liezl C. (Davao del Sur State College, 2025-05)
    Mangrove ecosystems play a crucial role in carbon sequestration and climate change mitigation. However, these functions remain understudied in Sta. Cruz, Davao del Sur. Thus, this study assessed the mangrove community structure, aboveground biomass, and carbon stock in the area. Thirty-six 10 x 10 m transect plots were established for tree inventory and measurement. The mangrove forest consists of five species from three families, exhibiting low species diversity (H'=0.83) and significant species dominance (D=0.53), yet high evenness (J'=0.70). Among sites, Tuban had the highest diversity (H'=1.04), and evenness (J=0.94), with no dominant species (D=0.37). Avicennia marina was the most abundant species (RA=67.80%) and had the highest importance value (IVI= 114.77%). Despite its limited population, Sonneratia alba contributed the most to aboveground biomass (x= 110.11 Mg ha-1) and carbon stock (x=52.85 MgC ha-1). A weak negative correlation (rs= -0.1) was observed between species importance, aboveground biomass, and carbon stock. The mangrove forest's average aboveground biomass (43.87 Mg ha-1) aligned with IPCC default values, while its carbon stock (21.06 MgC ha-1) was comparatively lower. These baseline data suggest that while the area retains considerable biomass, but less carbon stock and low biodiversity, underscoring the need for targeted conservation efforts to enhance the ecosystem's stability and ecological function.
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    Species composition, diversity, abundance, and microhabitat preferences of anuran species in the Miral river, Bansalan, Davao del Sur
    Ubat, Drahcir E. (Davao del Sur State College, 2025-05)
    A comprehensive anuran survey was conducted across three sites along the Miral River in Bansalan, Davao del Sur—Barangay Managa (upstream), Barangay Tubod (midstream), and Barangay Poblacion Uno (downstream). Using 270 man-hours of cruising and mark-release-technique, the survey documented anuran species, assessed habitat associations, and generated baseline data on Mindanao's amphibian diversity. A total of 104 anuran individuals were recorded, representing six species and four families, with 67% being non-endemics and 33% endemic to the Mindanao faunal region. Limnonectes magnus was noted as nearly threatened. Species diversity was highest upstream (H' = 1.52, S = 6), moderate midstream (H' = 1.05, S = 4), and lowest downstream (H = 0.43, S = 2), but were not statistically significant (p = 0.2193). While species composition varied between sites (p = 0.1875). Most anurans utilized both aquatic and terrestrial microhabitats, indicating microhabitat overlap. This study revealed that Rhinella marina was strongly linked to warmer water, higher pH, and elevated air temperature—conditions typical of downstream habitats. Conversely, upstream habitats, with dense canopy, abundant moss, leaf litter, and minimal disturbance, supported species like Polypedates leucomystax and Kaloula pulchra. Obviously, principal component analysis revealed that elevation was the most influential environmental factor with strong association habitat variables affecting anuran preferences. Endemic species were associated with intact forest areas, though signs of forest clearing for agriculture indicated environmental stress. The dominance of invasive species and the low presence of the near-threatened Limnonectes magnus underscore the urgent need for conservation efforts to protect native amphibians and restore natural habitats in the Miral River ecosystem.