#nsmnp

The study was carried out to assess the woody species of the lowland forest over limestone in the Northern Sierra Madre Natural Park (NSMNP) in Palanan, Isabela, Northeast Luzon, Philippines in order to provide information of its floral diversity, endemism and conservation status. An updated species list was provided based on the recent field survey and analysis of herbarium records. A total of 138 woody species in 92 genera and 42 families were recorded consisting of three lianas, 34 shrubs and 101 small to large trees. The ten most speciose families were Meliaceae (13 spp.) Rubiaceae (8 spp.), Annonaceae (7 spp.), Ebenaceae (7 spp.), Fabaceae (7 spp.), Dipterocarpaceae (7 spp.), Myrtaceae (6 spp.), Primulaceae (5 spp.), Rutaceae (5 spp.), and Vitaceae (5 spp.). Genus Diospyros of the family Ebenaceae had the highest number of species (7) followed by genera Ficus (6), Shorea (5), Syzygium (5), and Leea (5). The most important species was Diospyros pyrrhocarpa Miq. Species endemism is very high, 41% (56) of the total number of species, nine (9) of which are single-island endemics known only to Luzon Island. Twenty-two (22) were threatened species, one being critically endangered, two are endangered, 15 are vulnerable and four are near threatened. The information provided is crucial in the management of the natural park, which requires serious monitoring and protection.