Abunan, Jericho T.2026-09-142026-09-142024-05Abunan, J. T. (2024). Fern diversity in Don Mariano Marcos Memorial State University forest reserve, Bacnotan, La Union, Philippines. [Unpublished Undergraduate Thesis]. Don Mariano Marcos Memorial State University – North La Union Campus, Sapilang Bacnotan, La Union. Lakasa ti Sirib, DMMMSU Institutional Repository.https://lakasa.dmmmsu.edu.ph/handle/123456789/2548This research assessed the diversity, conservation status, and endemism of ferns in the Forest Reserve of Don Mariano Marcos Memorial State University- North La Union Campus, Sapilang, Bacnotan, La Union. Two repeated transect walks were done with a total of 26 plots (10 plots from area one and 16 plots from area two). Specimens were collected, identified, and assessed for their conservation status and endemism. The inventory revealed 14 species under five families of ferns in the study area. The study shows that eight were identified as endemic in the Philippines and four were identified as widely distributed not only in the Philippines but also in other countries. The species that has the highest relative density and important value was the Arthropteris palisotii (Desv.) Alston, while the species that ranked first in terms of relative frequency was Adiantum philippense L. The species that has the highest fresh and dry weight of all the species is Nephrolepsis acutifolia (Desv) Crists. Moreover, the result of the study showed a high diversity index (0.90) and low level of diversity (2.36). Generally, the study shows the unbalanced distribution of fern species in the DMMMSU Forest Reserve.en587.3 — Polypodiopsida (Ferns)Ferns — PhilippinesBiodiversity — PhilippinesForest reserves — PhilippinesPlant diversity — PhilippinesForests and forestry — PhilippinesThesis