The study aimed to evaluate the present condition of the ecotone ecosystem and generate biodiversity mapping particularly the endemic plants, unique plants and keystone species of the said ecotone ecosystem. The ecotone ecosystem was evaluated by means of an assessment and collection of different plants. Determination of the possible threats and problems that could affect the plant’s habitat was also conducted.  A total of 36 species of plants were identified and classified, and these were grouped into 4 divisions, 6 classes, 20 orders, 27 families and 32 genera. There are eighteen (18) endemic plants and eight (9) unique species that were observed in the ecotone ecosystem of Sitio Bulac, Barangay General Luna, Carranglan Nueva Ecija. Grewia philippinensis Perk. is considered to be the keystone species. The diversity of plants in the ecotone ecosystem of Sitio Bulac, Brgy. General Luna is still high however, different threats in to human activities such as kaingin farming, illegal logging, fires, pollution, mining, charcoal making, wildlife hunting, firewood collection and land conversion were present in the area which could affect the ecotone ecosystem and its biodiversity. Hence, protection and conservation of ecotone ecosystem is very important to prevent biodiversity loss and economic loss.  Keywords :  Biodiversity  assessment, diversity index, endemic plants, unique species, environmental degradation