Assessing the diversity of plants in a one-hectare plot in Mt. Musuan [in Maramag, Bukidnon, Philippines]

Inventory of trees in the 1-ha plot revealed a total of 78 species with 65 genera, 36 families, and a total of 419 individuals of trees. Conversely, the six sampling plots with a total area of 2,400 sq m had 30 species, 28 genera, and 22 families. It has an average species richness of 8.1 species / 20 m x 20 m plot. The species diversity of trees in different sites showed a mean diversity value of H = 0.77. In particular, Senna spectabilis and Orania decipiens obtained the highest density values being represented by the most individuals with 95 (for S. spectabilis) and 64 (for O. decipiens) individuals, respectively. Senna spectabilis also had the highest frequency value in the lower and middle forest layers while it was Oroxylum indicum, which has the highest frequency in the upper forest layer. The upper forest layer has the highest dominance value followed by the middle and lower forest layers. Likewise, the highest diversity value for trees were noted in the upper forest layer with H = 0.93 followed by the middle forest layer with H = 0.86 and the lowest was observed in the lower forest layer with H = 0.53. In these three forest layers, Vitex glabrata, Litsea perrottetii, and Ficus balete obtained the highest dominance values with a dbh of 120 cm, 71 cm, and 64 cm, respectively while Senna spectabilis, Litsea perrottetii, and Vitex glabrata obtained the highest SIV. In addition, the tree profile diagram which indicates species richness, crown cover, height, and species distribution, showed an increase in the height of trees from the lower to the upper forest layers as the highest mean height (6.07m) of trees was found in the upper forest layer followed by the middle (5.7m) and the lower (4.2m) forest layers. The middle layer of the forest had the most number of individuals (41) while the lower and upper layers both had 23 individuals. It was also found out that tree endemism within the 1 ha plot was quite low. On the contrary, endemicity within the entire Mt. Musuan was reported to be high considering the total plant species. Assessment of the conservation status of trees showed 3 vulnerable species, and 1 critically endangered species, 5 endemic species, 17 depleted species, 5 common species, 4 rare species, and 32 economically important species. The critically endangered species identified was Pterocarpus indicus , while the four endemic species included Canarga odorata, Gochidion triandrum, Palaquim foxworthyi, and Kleinhovia hospital.