DIVERSITY OF TREES AND SHRUBS ALONG DIFFERENT VEGETATION TYPES IN MT. HAMIGUITAN RANGE, DAVAO ORIENTAL, MINDANAO ISLAND, PHILIPPINES

Abstract

Mt. Hamiguitan Range in Davao Oriental, Mindanao Island, Philippines is the only protected area with pygmy forest and a priority site for protection and conservation. This range harbors different vegetation types such as agroecosystem, dipterocarp, montane and mossy forests . This study was conducted to determine the diversity of trees and shrubs along vegetation types. Transect walk and 16 sampling plots of 20 x 20 m were established in the different vegetation types. Specimens collected were classified and identified using the Flora Malesiana and type images. Assessment of the status was determined based on International Union for the Conservation of Nature (IUCN). Findings of the study revealed, 223 species of trees with 141 genera and 71 families, while 46 species of shrubs with 26 genera and 21 families. Respective to the vegetation types, the pygmy forest obtained a comparatively high diversity value for trees and shrubs followed by montane forest. The high species importance value (SIV) of Diospyros philippinensis for trees and Medinilla apoensis for shrubs indicates that these species have an important role in regulating the stability of the ecosystem. Species similarities of trees and shrubs were highest between the montane and pygmy forests. The tree profile of this vegetation type is different due to the ultramafic substrate causing the dwarfism of trees in the pygmy forest, thus, given higher priority for protection and conservation.