Northern Sierra Madre Natural Park (NSMNP)

The NSMNP has a high level of biodiversity due to its relatively pristine state that includes an equally diverse primary forest containing a variety of habitats. Its topographic and spatial variations and the influence of climate on its vegetation may have resulted in adaptations to a monsoonal type (with less pronounced dry season) than to a distinct dry and wet season found in other parts of the country. These conditions are conducive to speciation.

Endemic plants in the NSMNP include dipterocarps, (Shorea spp. and Hopea spp.), orchids (Dendrobium aclinia and Eulophia dentata), the leguminous trees (Milletia longipes) and a member the citrus family, Swinglea glutinosa, an endemic genus.

The fauna includes a significant number of endemic species: Danielsen et al., 1991 reported that 75 of the recorded bird species are endemic to the Philippines and another 20 species are narrowly restricted to Luzon. An expedition in 1961 resulted in the collection of 94 species of birds and 16 species of mammals. A 1991 survey recorded 102 species of birds of which 21 are widespread Philippine endemics and 11 restricted to Luzon and satellite islands. Recorded for mammals are 21 species. There is meager information on reptiles and amphibians.