Plant species diversity and assessment in Quezon Protected Landscape, Southern Luzon, Philippines

Abstract

Quezon Protected Landscape (QPL) is a tropical rainforest situated at the southern Sierra Madre mountain range. However, it is subjected to anthropogenic pressure that poses threats to its flora and fauna. This study was conducted to describe the plant diversity, assess their ecological and conservation status, and to identify current anthropogenic threats in various vegetation types in QPL. Vegetation assessment was done using quadrat method established at different land use types wherein ninety 10×10 m nested plots were used for trees, 5×5 m subplots were used for herbs and shrubs, and 1×1 m subplots were used for grasses. The study documented a total of 328 species belonging to 84 families and 208 genera with 2,737 individuals. Species diversity is high as revealed by the values obtained from species diversity (H’) and species evenness (J’) indexes. Out of 172 tree species identified, the most important species are: Parashorea malaanonan (Blanco) Merr. in the regenerating and lowland evergreen dipterocarp forest; Diospyros pyrrhocarpa Miq. in the karst forest; Leucaena leucocephala (Lam.) de Wit in the secondary forest; and Cocos nucifera L. in the agroforest. Assessment of ecological status showed that out of 328 species, 213 (64.94%) are native, wherein 65 (19.8%) are endemic, and 115 (35.06%) are introduced. Forty-five species (13.72%) are threatened in which 25 of those are endemic in the Philippines. Overall, QPL has a wide array of plant species and threats such as the illegal extraction of natural resources, encroachment, cleanliness and presence of invasive alien species. So, it is recommended that protection and awareness campaign should be done for conservation and sustainability. KEYWORDS: Importance Value Index, invasive species, species diversity, threatened species, vegetation analysis